fix(schema): keep legacy blobs on replay, import, and V1 migration

Freeze session.message.content.updated at the stored shape and translate on replay, run persisted() on CLI session import, write native from the V1 migration, regenerate the OpenAPI docs, and mirror text.ended state in the client fold.
test(core): use native for text and reasoning provider blobs
2026-09-22 16:47:34 +00:00 · 2026-09-22 00:37:59 -05:00 · 2026-09-21 23:39:41 -05:00 · 2026-09-21 23:37:54 -05:00 · 2026-09-21 23:30:38 -05:00 · 2026-09-21 23:27:12 -05:00
399 changed files with 8244 additions and 2585 deletions
@@ -112,11 +112,12 @@ jobs:
      - name: Run unit tests
        timeout-minutes: 20
        run: |
+          # The runners have four vCPUs, and each Bun test process performs its own concurrent work.
          if [ "${{ github.event_name }}" = "workflow_dispatch" ]; then
-            GITHUB_ACTIONS=false bun turbo test
+            GITHUB_ACTIONS=false bun turbo test --concurrency=3
            exit 0
          fi
-          GITHUB_ACTIONS=false bun turbo test --affected
+          GITHUB_ACTIONS=false bun turbo test --affected --concurrency=3
        env:
          OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER: ${{ runner.os == 'Windows' && 'true' || 'false' }}
          TURBO_SCM_BASE: ${{ github.event_name == 'pull_request' && format('{0}^1', github.sha) || github.event.before }}
@@ -32,7 +32,7 @@
    },
    "packages/ai": {
      "name": "@opencode/ai",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@aws-sdk/credential-providers": "3.1057.0",
        "@opencode/schema": "workspace:*",
@@ -54,7 +54,7 @@
    },
    "packages/app": {
      "name": "@opencode/app",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@corvu/drawer": "catalog:",
        "@dnd-kit/abstract": "0.5.0",
@@ -111,7 +111,7 @@
    },
    "packages/cli": {
      "name": "@opencode/cli",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "bin": {
        "opencode2": "./bin/opencode2.cjs",
      },
@@ -175,7 +175,7 @@
    },
    "packages/client": {
      "name": "@opencode/client",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@opencode/protocol": "workspace:*",
        "@opencode/schema": "workspace:*",
@@ -201,7 +201,7 @@
    },
    "packages/codemode": {
      "name": "@opencode/codemode",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "acorn": "8.15.0",
        "effect": "catalog:",
@@ -214,7 +214,7 @@
    },
    "packages/console/app": {
      "name": "@opencode/console-app",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@cloudflare/vite-plugin": "1.15.2",
        "@ibm/plex": "6.4.1",
@@ -250,7 +250,7 @@
    },
    "packages/console/core": {
      "name": "@opencode/console-core",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@aws-sdk/client-sts": "3.782.0",
        "@jsx-email/render": "1.1.1",
@@ -277,7 +277,7 @@
    },
    "packages/console/function": {
      "name": "@opencode/console-function",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@openauthjs/openauth": "0.0.0-20250322224806",
        "@opencode/console-core": "workspace:*",
@@ -294,7 +294,7 @@
    },
    "packages/console/mail": {
      "name": "@opencode/console-mail",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@jsx-email/all": "2.2.3",
        "@jsx-email/cli": "1.4.3",
@@ -318,7 +318,7 @@
    },
    "packages/console/support": {
      "name": "@opencode/console-support",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@cloudflare/vite-plugin": "1.15.2",
        "@opencode/console-core": "workspace:*",
@@ -338,7 +338,7 @@
    },
    "packages/core": {
      "name": "@opencode/core",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@ai-sdk/cohere": "3.0.27",
        "@ai-sdk/gateway": "3.0.104",
@@ -406,10 +406,10 @@
    },
    "packages/desktop": {
      "name": "@opencode/desktop",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@zip.js/zip.js": "2.7.62",
-        "electron-context-menu": "4.1.2",
+        "electron-context-menu": "5.0.0",
        "electron-log": "^5",
        "electron-updater": "6.8.9",
        "lighthouse": "13.4.1",
@@ -436,7 +436,7 @@
        "drizzle-kit": "catalog:",
        "drizzle-orm": "catalog:",
        "effect": "catalog:",
-        "electron": "42.10.1",
+        "electron": "44.4.3",
        "electron-builder": "26.15.7",
        "electron-vite": "6.0.0-beta.1",
        "puppeteer-core": "25.9.0",
@@ -455,7 +455,7 @@
    },
    "packages/enterprise": {
      "name": "@opencode/enterprise",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@hono/standard-validator": "catalog:",
        "@opencode-ai/sdk": "1.18.21",
@@ -492,7 +492,7 @@
    },
    "packages/function": {
      "name": "@opencode/function",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@octokit/auth-app": "8.0.1",
        "@octokit/rest": "catalog:",
@@ -508,7 +508,7 @@
    },
    "packages/http-recorder": {
      "name": "@opencode/http-recorder",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@effect/platform-node-shared": "4.0.0-rc.112",
      },
@@ -527,7 +527,7 @@
    },
    "packages/httpapi-codegen": {
      "name": "@opencode/httpapi-codegen",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "effect": "catalog:",
        "prettier": "3.6.2",
@@ -540,7 +540,7 @@
    },
    "packages/latex": {
      "name": "@opencode/latex",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@opencode/plugin": "workspace:*",
        "@opentui/core": "catalog:",
@@ -554,7 +554,7 @@
    },
    "packages/merman": {
      "name": "@opencode/merman",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@opencode/plugin": "workspace:*",
        "@opentui/core": "catalog:",
@@ -569,7 +569,7 @@
    },
    "packages/plugin": {
      "name": "@opencode/plugin",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@ai-sdk/provider": "3.0.8",
        "@opencode/ai": "workspace:*",
@@ -608,7 +608,7 @@
    },
    "packages/plugin-browser": {
      "name": "@opencode/plugin-browser",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@opencode/plugin": "workspace:*",
        "@opencode/schema": "workspace:*",
@@ -638,7 +638,7 @@
    },
    "packages/protocol": {
      "name": "@opencode/protocol",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@opencode/schema": "workspace:*",
        "effect": "catalog:",
@@ -653,7 +653,7 @@
    },
    "packages/schema": {
      "name": "@opencode/schema",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@standard-schema/spec": "catalog:",
        "effect": "catalog:",
@@ -677,7 +677,7 @@
    },
    "packages/sdk": {
      "name": "@opencode/sdk",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@opencode/client": "workspace:*",
        "@opencode/core": "workspace:*",
@@ -698,7 +698,7 @@
    },
    "packages/server": {
      "name": "@opencode/server",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@effect/platform-node": "catalog:",
        "@effect/platform-node-shared": "catalog:",
@@ -720,7 +720,7 @@
    },
    "packages/session-ui": {
      "name": "@opencode/session-ui",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@kobalte/core": "catalog:",
        "@opencode/client": "workspace:*",
@@ -755,7 +755,7 @@
    },
    "packages/simulation": {
      "name": "@opencode/simulation",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@opencode/ai": "workspace:*",
        "@opencode/core": "workspace:*",
@@ -775,7 +775,7 @@
    },
    "packages/stats/app": {
      "name": "@opencode/stats-app",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@ibm/plex": "6.4.1",
        "@kobalte/core": "catalog:",
@@ -809,7 +809,7 @@
    },
    "packages/stats/core": {
      "name": "@opencode/stats-core",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@aws-sdk/client-athena": "3.933.0",
        "@planetscale/database": "1.19.0",
@@ -828,7 +828,7 @@
    },
    "packages/stats/server": {
      "name": "@opencode/stats-server",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@aws-sdk/client-firehose": "3.933.0",
        "@effect/platform-node": "catalog:",
@@ -874,7 +874,7 @@
    },
    "packages/theme": {
      "name": "@opencode/theme",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@opentui/core": "catalog:",
        "effect": "catalog:",
@@ -888,7 +888,7 @@
    },
    "packages/tui": {
      "name": "@opencode/tui",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@opencode/client": "workspace:*",
        "@opencode/core": "workspace:*",
@@ -923,7 +923,7 @@
    },
    "packages/ui": {
      "name": "@opencode/ui",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@kobalte/core": "catalog:",
        "@pierre/diffs": "catalog:",
@@ -958,7 +958,7 @@
    },
    "packages/util": {
      "name": "@opencode/util",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@effect/opentelemetry": "catalog:",
        "@effect/platform-node": "catalog:",
@@ -991,7 +991,7 @@
    },
    "packages/web": {
      "name": "@opencode/web",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "@astrojs/cloudflare": "12.6.3",
        "@astrojs/markdown-remark": "6.3.1",
@@ -1032,7 +1032,7 @@
    },
    "services/update": {
      "name": "@opencode/update",
-      "version": "2.0.10",
+      "version": "2.0.12",
      "dependencies": {
        "jose": "6.0.11",
        "semver": "catalog:",
@@ -3880,13 +3880,13 @@

    "ejs": ["ejs@3.1.10", "", { "dependencies": { "jake": "^10.8.5" }, "bin": { "ejs": "bin/cli.js" } }, "sha512-UeJmFfOrAQS8OJWPZ4qtgHyWExa088/MtK5UEyoJGFH67cDEXkZSviOiKRCZ4Xij0zxI3JECgYs3oKx+AizQBA=="],

-    "electron": ["electron@42.10.1", "", { "dependencies": { "@electron-internal/extract-zip": "^1.0.1", "@electron/get": "^5.0.0", "@types/node": "^24.9.0" }, "bin": { "electron": "cli.js", "install-electron": "install.js" } }, "sha512-ITc1HPeoDzsxCCaH6MFsN67Nq2nUiJf5N9pBWxzhUpFfKJF0IwiAkKT3emg1lPbvC4OfFE+Cdwe4vhgdOZ1YKg=="],
+    "electron": ["electron@44.4.3", "", { "dependencies": { "@electron-internal/extract-zip": "^1.0.1", "@electron/get": "^5.0.0", "@types/node": "^24.9.0" }, "bin": { "electron": "cli.js", "install-electron": "install.js" } }, "sha512-LTpSFTB40qVCXIX5xMo+cgHI/Jjkbjw7VpB26PccEbroqOn72LBukeaDwPVo1fBYzSzs0c9iPuAucFCO7Tw81Q=="],

    "electron-builder": ["electron-builder@26.15.7", "", { "dependencies": { "app-builder-lib": "26.15.7", "builder-util": "26.15.3", "builder-util-runtime": "9.7.0", "chalk": "^4.1.2", "ci-info": "^4.2.0", "dmg-builder": "26.15.7", "fs-extra": "^10.1.0", "lazy-val": "^1.0.5", "simple-update-notifier": "2.0.0", "yargs": "^17.6.2" }, "bin": { "electron-builder": "./cli.js", "install-app-deps": "./install-app-deps.js" } }, "sha512-DBpaNzxsPs1BvEblzFoNriSbzsBqDCy/gseIngeEhYzQG1IxfB7Hvc2tBBVmpWE2BTQGP9J1RrAvDT+Vc/uAxg=="],

    "electron-builder-squirrel-windows": ["electron-builder-squirrel-windows@26.15.7", "", { "dependencies": { "app-builder-lib": "26.15.7", "builder-util": "26.15.3", "electron-winstaller": "5.4.0" } }, "sha512-B4uvn2NzFSuf084udWqugludFull6CRJiWe2dLzMnZLl6G5hdAGk0fsBMGlBSpKjvQCJn8IPc+S7OnJ+GXqwLA=="],

-    "electron-context-menu": ["electron-context-menu@4.1.2", "", { "dependencies": { "cli-truncate": "^4.0.0", "electron-dl": "^4.0.0", "electron-is-dev": "^3.0.1" } }, "sha512-9xYTUV0oRqKL50N9W71IrXNdVRB0LuBp3R1zkUdUc2wfIa2/QZwYYj5RLuO7Tn7ZSLVIaO3X6u+EIBK+cBvzrQ=="],
+    "electron-context-menu": ["electron-context-menu@5.0.0", "", { "dependencies": { "cli-truncate": "^4.0.0", "electron-dl": "^4.0.0", "electron-is-dev": "^3.0.1" } }, "sha512-rgFpRtwY0/rhsRCoz9rE6VM4WueEsLbIpca7ucOhERVrbGB2dQrxa9xwBNLplU54jRgPuv6nTEbxoplE5bzy2A=="],

    "electron-dl": ["electron-dl@4.0.0", "", { "dependencies": { "ext-name": "^5.0.0", "pupa": "^3.1.0", "unused-filename": "^4.0.1" } }, "sha512-USiB9816d2JzKv0LiSbreRfTg5lDk3lWh0vlx/gugCO92ZIJkHVH0UM18EHvKeadErP6Xn4yiTphWzYfbA2Ong=="],

@@ -1,8 +1,8 @@
 {
  "nodeModules": {
-    "x86_64-linux": "sha256-8mOzCscBAuogG4tm8CroqjTX5E5yzCvTobbhKvxQP0U=",
-    "aarch64-linux": "sha256-drrRSpzxC8bfaTXBpOyaN0QAyBVV7WJzm0NstJ+8sAE=",
-    "aarch64-darwin": "sha256-YY5A/zxLPONvgnI+DZlzcD2K5Q9PIw4F2YbDxKbT4UU=",
-    "x86_64-darwin": "sha256-/c/Ew4onA+9+l6GRKXz3zWq3QFESM7j5RyGLCWRPQFw="
+    "x86_64-linux": "sha256-/jah4P2a0aGJNJ0aMdlFEbGHAXx33lqxHbc7UmpLFDg=",
+    "aarch64-linux": "sha256-L3SoZ24qNXicsE2FK6LATQjOmjPxY679RjugrUyO/1Y=",
+    "aarch64-darwin": "sha256-pI9NT8KWUPi+JCk6DYMqIAYmBqTbi13uL4VdNV3WS6Y=",
+    "x86_64-darwin": "sha256-rMAGhTTz46KA5Ya7E5J0af7Bn1QzTDhTaNfNJm8qfsw="
  }
 }
@@ -2,7 +2,7 @@
  "$schema": "https://json.schemastore.org/package.json",
  "name": "opencode",
  "description": "AI-powered development tool",
-  "version": "2.0.10",
+  "version": "2.0.12",
  "private": true,
  "type": "module",
  "packageManager": "bun@1.4.2",
@@ -29,6 +29,47 @@ await Effect.runPromise(program.pipe(Effect.provide(llmLayer)))

 Run `LLMClient.stream(request)` instead of `generate` when you want incremental `LLMEvent`s. The event stream is provider-neutral — same shape across OpenAI Chat, OpenAI Responses, Anthropic Messages, Gemini, Bedrock Converse, and any OpenAI-compatible deployment.

+## Experimental evaluation
+
+Evaluation models compare shared state with typed choice, score, and boolean questions. The API is
+isolated under an experimental entrypoint and provider namespace while the contract evolves:
+
+```ts
+import { Effect } from "effect"
+import { Evaluation, EvaluationClient } from "@opencode/ai/experimental"
+import { TypeSafeAI } from "@opencode/ai/providers"
+
+const model = TypeSafeAI.configure().experimental.evaluation("jev-latest")
+
+const program = Evaluation.evaluate({
+  model,
+  state: "I was charged twice. Please refund the duplicate payment.",
+  questions: {
+    department: {
+      type: "choice",
+      instructions: "Which team should handle this?",
+      criteria: { billing: "Payments and refunds", technical: "Bugs and outages" },
+    },
+    urgency: {
+      type: "score",
+      instructions: "How urgent is this?",
+      criteria: ["Can wait", "Needs prompt attention", "Blocking revenue"],
+    },
+    refund: { type: "boolean", instructions: "Is the customer asking for a refund?" },
+  },
+})
+
+const response = await Effect.runPromise(program.pipe(Effect.provide(EvaluationClient.fetchLayer)))
+
+console.log(response.answers.department.choice)
+console.log(response.answers.refund.probability)
+```
+
+`TypeSafeAI` reads `TYPESAFE_API_KEY`. `OpenCodeZen` exposes the same selector and reads
+`OPENCODE_API_KEY`. The common API uses `boolean`; System One routes lower it to native `noul`.
+Choice and score confidence plus score legends remain available in provider metadata, and the
+provider's rounded probabilities are returned unchanged.
+
 ## Alibaba Cloud Model Studio

 `Alibaba` provides standard Model Studio inference. Configure a region explicitly, then select
@@ -1,6 +1,6 @@
 {
  "$schema": "https://json.schemastore.org/package.json",
-  "version": "2.0.10",
+  "version": "2.0.12",
  "name": "@opencode/ai",
  "type": "module",
  "license": "MIT",
@@ -0,0 +1,29 @@
+export { EvaluationClient } from "./experimental/evaluation-client.js"
+export {
+  BooleanAnswer,
+  BooleanQuestion,
+  ChoiceAnswer,
+  ChoiceQuestion,
+  Evaluation,
+  EvaluationAnswer,
+  EvaluationInput,
+  EvaluationModel,
+  EvaluationModelSchema,
+  EvaluationQuestion,
+  EvaluationRequest,
+  EvaluationResponse,
+  EvaluationRounding,
+  ScoreAnswer,
+  ScoreQuestion,
+} from "./experimental/evaluation.js"
+export type {
+  AnswerFor,
+  AnswersFor,
+  EvaluationModelOptions,
+  EvaluationOptions,
+  EvaluationQuestions,
+  EvaluationRequestFor,
+  EvaluationRequestInput,
+  EvaluationResponseFor,
+  EvaluationRoute,
+} from "./experimental/evaluation.js"
@@ -0,0 +1,54 @@
+import { Context, Effect, Layer } from "effect"
+import { RequestExecutor } from "../route/executor.js"
+import { mergeHttpOptions, type AIError } from "../schema/index.js"
+import { sanitizeSurrogates } from "../utils/sanitize.js"
+import {
+  type EvaluationOptions,
+  type EvaluationQuestions,
+  type EvaluationRequestFor,
+  type EvaluationResponseFor,
+} from "./evaluation.js"
+
+export type Execute = RequestExecutor.Interface["execute"]
+
+export interface Interface {
+  readonly evaluate: <Options extends EvaluationOptions, const Questions extends EvaluationQuestions>(
+    request: EvaluationRequestFor<Options, Questions>,
+  ) => Effect.Effect<EvaluationResponseFor<Questions>, AIError>
+}
+
+export class Service extends Context.Service<Service, Interface>()("@opencode/AI/Experimental/EvaluationClient") {}
+
+export const evaluate = <Options extends EvaluationOptions, const Questions extends EvaluationQuestions>(
+  request: EvaluationRequestFor<Options, Questions>,
+): Effect.Effect<EvaluationResponseFor<Questions>, AIError, Service> =>
+  Effect.flatMap(Service, (client) => client.evaluate(request))
+
+export const layer: Layer.Layer<Service, never, RequestExecutor.Service> = Layer.effect(
+  Service,
+  Effect.gen(function* () {
+    const executor = yield* RequestExecutor.Service
+    return Service.of({
+      evaluate: (request) =>
+        request.model.route.evaluate(
+          {
+            ...sanitizeSurrogates({
+              ...request,
+              model: undefined,
+              http: mergeHttpOptions(request.model.http, request.http),
+            }),
+            model: request.model,
+          },
+          executor.execute,
+        ),
+    })
+  }),
+)
+export const fetchLayer = layer.pipe(Layer.provide(RequestExecutor.fetchLayer))
+
+export const EvaluationClient = {
+  Service,
+  layer,
+  fetchLayer,
+  evaluate,
+} as const
@@ -0,0 +1,245 @@
+import { Effect, Schema } from "effect"
+import {
+  AIError,
+  HttpOptions,
+  InvalidRequestError,
+  ModelID,
+  ProviderID,
+  ProviderMetadata,
+  Usage,
+} from "../schema/index.js"
+import { EvaluationClient, Service, type Execute } from "./evaluation-client.js"
+
+export const EvaluationInput = Schema.Union([Schema.String, Schema.JsonObject, Schema.Array(Schema.Json)])
+export type EvaluationInput = Schema.Schema.Type<typeof EvaluationInput>
+
+const EvaluationCriterion = Schema.NullOr(EvaluationInput)
+const ChoiceCriteria = Schema.Record(Schema.String, EvaluationCriterion).pipe(
+  Schema.refine((x): x is typeof x => Object.keys(x).length > 0, {
+    message: "Choice criteria must be a nonempty option map",
+  }),
+)
+
+export const ChoiceQuestion = Schema.Struct({
+  type: Schema.Literal("choice"),
+  instructions: EvaluationInput,
+  criteria: ChoiceCriteria,
+})
+export type ChoiceQuestion = Schema.Schema.Type<typeof ChoiceQuestion>
+
+export const ScoreQuestion = Schema.Struct({
+  type: Schema.Literal("score"),
+  instructions: EvaluationInput,
+  criteria: Schema.Array(EvaluationCriterion).check(Schema.isMinLength(2)),
+})
+export type ScoreQuestion = Schema.Schema.Type<typeof ScoreQuestion>
+
+export const BooleanQuestion = Schema.Struct({
+  type: Schema.Literal("boolean"),
+  instructions: EvaluationInput,
+  criteria: Schema.optional(
+    Schema.Struct({
+      true: Schema.optional(EvaluationCriterion),
+      false: Schema.optional(EvaluationCriterion),
+    }),
+  ),
+})
+export type BooleanQuestion = Schema.Schema.Type<typeof BooleanQuestion>
+
+export const EvaluationQuestion = Schema.Union([ChoiceQuestion, ScoreQuestion, BooleanQuestion]).pipe(
+  Schema.toTaggedUnion("type"),
+)
+export type EvaluationQuestion = Schema.Schema.Type<typeof EvaluationQuestion>
+export type EvaluationQuestions = Readonly<Record<string, EvaluationQuestion>>
+const EvaluationQuestions = Schema.Record(Schema.String, EvaluationQuestion).pipe(
+  Schema.refine((x): x is typeof x => Object.keys(x).length > 0, {
+    message: "Evaluation questions must be a nonempty map",
+  }),
+)
+
+const Probability = Schema.Number.check(Schema.isBetween({ minimum: 0, maximum: 1 }))
+
+export const ChoiceAnswer = Schema.Struct({
+  type: Schema.Literal("choice"),
+  choice: Schema.String,
+  probabilities: Schema.optional(Schema.Record(Schema.String, Probability)),
+})
+export type ChoiceAnswer = Schema.Schema.Type<typeof ChoiceAnswer>
+
+export const ScoreAnswer = Schema.Struct({
+  type: Schema.Literal("score"),
+  score: Schema.Number,
+  probabilities: Schema.optional(Schema.Record(Schema.String, Probability)),
+})
+export type ScoreAnswer = Schema.Schema.Type<typeof ScoreAnswer>
+
+export const BooleanAnswer = Schema.Struct({
+  type: Schema.Literal("boolean"),
+  probability: Probability,
+})
+export type BooleanAnswer = Schema.Schema.Type<typeof BooleanAnswer>
+
+export const EvaluationAnswer = Schema.Union([ChoiceAnswer, ScoreAnswer, BooleanAnswer]).pipe(
+  Schema.toTaggedUnion("type"),
+)
+export type EvaluationAnswer = Schema.Schema.Type<typeof EvaluationAnswer>
+
+export type AnswerFor<Question extends EvaluationQuestion> = Question extends {
+  readonly type: "choice"
+  readonly criteria: infer Criteria
+}
+  ? {
+      readonly type: "choice"
+      readonly choice: Extract<keyof Criteria, string>
+      readonly probabilities?: Readonly<Record<Extract<keyof Criteria, string>, number>>
+    }
+  : Question extends { readonly type: "score" }
+    ? ScoreAnswer
+    : BooleanAnswer
+
+export type AnswersFor<Questions extends EvaluationQuestions> = {
+  readonly [ID in keyof Questions]: AnswerFor<Questions[ID]>
+}
+
+export type EvaluationOptions = Record<string, unknown>
+
+export interface EvaluationRoute<Options extends EvaluationOptions = EvaluationOptions> {
+  readonly id: string
+  readonly evaluate: <const Questions extends EvaluationQuestions>(
+    request: EvaluationRequestFor<Options, Questions>,
+    execute: Execute,
+  ) => Effect.Effect<EvaluationResponseFor<Questions>, AIError>
+}
+
+export class EvaluationModel<Options extends EvaluationOptions = EvaluationOptions> {
+  declare protected readonly _Options: (options: Options) => Options
+  readonly id: ModelID
+  readonly provider: ProviderID
+  readonly route: EvaluationRoute<Options>
+  readonly http?: HttpOptions
+
+  constructor(input: EvaluationModel.Input<Options>) {
+    this.id = input.id
+    this.provider = input.provider
+    this.route = input.route
+    this.http = input.http
+  }
+
+  static make<Options extends EvaluationOptions = EvaluationOptions>(input: EvaluationModel.MakeInput<Options>) {
+    return new EvaluationModel<Options>({
+      id: ModelID.make(input.id),
+      provider: ProviderID.make(input.provider),
+      route: input.route,
+      http: input.http,
+    })
+  }
+}
+
+export namespace EvaluationModel {
+  export interface Input<Options extends EvaluationOptions = EvaluationOptions> {
+    readonly id: ModelID
+    readonly provider: ProviderID
+    readonly route: EvaluationRoute<Options>
+    readonly http?: HttpOptions
+  }
+
+  export interface MakeInput<Options extends EvaluationOptions = EvaluationOptions>
+    extends Omit<Input<Options>, "id" | "provider"> {
+    readonly id: string | ModelID
+    readonly provider: string | ProviderID
+  }
+}
+
+export const EvaluationModelSchema = Schema.declare(
+  (value): value is EvaluationModel => value instanceof EvaluationModel,
+  {
+    expected: "Evaluation.Model",
+  },
+)
+
+export class EvaluationRequest extends Schema.Class<EvaluationRequest>("Evaluation.Request")({
+  model: EvaluationModelSchema,
+  state: EvaluationInput,
+  questions: EvaluationQuestions,
+  options: Schema.optional(Schema.Record(Schema.String, Schema.Unknown)),
+  http: Schema.optional(HttpOptions),
+}) {
+  declare protected readonly _EvaluationRequest: void
+}
+
+export type EvaluationModelOptions<Model> = Model extends EvaluationModel<infer Options> ? Options : never
+
+export type EvaluationRequestFor<
+  Options extends EvaluationOptions = EvaluationOptions,
+  Questions extends EvaluationQuestions = EvaluationQuestions,
+> = Omit<EvaluationRequest, "model" | "questions" | "options"> & {
+  readonly model: EvaluationModel<Options>
+  readonly questions: Questions
+  readonly options?: Options
+}
+
+export type EvaluationRequestInput<
+  Model extends object = EvaluationModel,
+  Questions extends EvaluationQuestions = EvaluationQuestions,
+> = Omit<ConstructorParameters<typeof EvaluationRequest>[0], "model" | "questions" | "options" | "http"> & {
+  readonly model: Model
+  readonly questions: Questions
+  readonly options?: NoInfer<EvaluationModelOptions<Model>>
+  readonly http?: HttpOptions.Input
+} & (Model extends EvaluationModel<EvaluationModelOptions<Model>> ? unknown : never)
+
+export class EvaluationRounding extends Schema.Class<EvaluationRounding>("Evaluation.Rounding")({
+  probabilityDecimals: Schema.optional(Schema.Int),
+  scoreDecimals: Schema.optional(Schema.Int),
+}) {}
+
+export class EvaluationResponse extends Schema.Class<EvaluationResponse>("Evaluation.Response")({
+  model: ModelID,
+  answers: Schema.Record(Schema.String, EvaluationAnswer),
+  usage: Schema.optional(Usage),
+  rounding: Schema.optional(EvaluationRounding),
+  providerMetadata: Schema.optional(ProviderMetadata),
+}) {}
+
+export type EvaluationResponseFor<Questions extends EvaluationQuestions> = Omit<EvaluationResponse, "answers"> & {
+  readonly answers: AnswersFor<Questions>
+}
+
+export function request<const Model extends object, const Questions extends EvaluationQuestions>(
+  input: EvaluationRequestInput<Model, Questions>,
+): EvaluationRequestFor<EvaluationModelOptions<Model>, Questions>
+export function request(input: EvaluationRequest): EvaluationRequest
+export function request(input: EvaluationRequest | EvaluationRequestInput) {
+  if (input instanceof EvaluationRequest) return input
+  return new EvaluationRequest({
+    ...input,
+    model: input.model as unknown as EvaluationModel,
+    http: input.http === undefined ? undefined : HttpOptions.make(input.http),
+  })
+}
+
+export function evaluate<const Model extends object, const Questions extends EvaluationQuestions>(
+  input: EvaluationRequestInput<Model, Questions>,
+): Effect.Effect<EvaluationResponseFor<Questions>, AIError, Service>
+export function evaluate(input: EvaluationRequest): Effect.Effect<EvaluationResponse, AIError, Service>
+export function evaluate(input: EvaluationRequest | EvaluationRequestInput) {
+  return Effect.try({
+    try: () => (input instanceof EvaluationRequest ? input : request(input)),
+    catch: (cause) =>
+      new AIError({
+        reason: new InvalidRequestError({
+          message: cause instanceof Error ? cause.message : String(cause),
+          cause,
+        }),
+      }),
+  }).pipe(
+    Effect.flatMap((request) =>
+      EvaluationClient.evaluate(request as EvaluationRequestFor<EvaluationOptions, EvaluationQuestions>),
+    ),
+  )
+}
+
+export const Evaluation = {
+  request,
+  evaluate,
+} as const
@@ -0,0 +1,222 @@
+import { Effect, Schema } from "effect"
+import { Headers, HttpClientRequest } from "effect/unstable/http"
+import {
+  BooleanAnswer,
+  ChoiceAnswer,
+  ChoiceQuestion,
+  EvaluationInput,
+  EvaluationModel,
+  EvaluationResponse,
+  EvaluationRounding,
+  ScoreAnswer,
+  ScoreQuestion,
+  type EvaluationResponseFor,
+  type EvaluationRoute,
+} from "./evaluation.js"
+import { Auth, type Definition as AuthDefinition } from "../route/auth.js"
+import {
+  AIError,
+  HttpContext,
+  HttpOptions,
+  InvalidProviderOutputError,
+  InvalidRequestError,
+  ModelID,
+  Usage,
+  mergeJsonRecords,
+} from "../schema/index.js"
+
+const Noul = Schema.Struct({
+  type: Schema.Literal("noul"),
+  instructions: EvaluationInput,
+  criteria: Schema.optional(
+    Schema.Struct({
+      true: Schema.optional(Schema.NullOr(EvaluationInput)),
+      false: Schema.optional(Schema.NullOr(EvaluationInput)),
+    }),
+  ),
+})
+const Question = Schema.Union([
+  ChoiceQuestion.pipe(
+    Schema.refine((x): x is typeof x => Object.keys(x.criteria).length <= 255, {
+      message: "System One Choice questions support at most 255 options",
+    }),
+  ),
+  ScoreQuestion.pipe(
+    Schema.refine((x): x is typeof x => x.criteria.length <= 10, {
+      message: "System One Score questions support at most 10 levels",
+    }),
+  ),
+  Noul,
+])
+const Request = Schema.StructWithRest(
+  Schema.Struct({
+    model: Schema.String,
+    state: EvaluationInput,
+    questions: Schema.Record(Schema.String, Question),
+  }),
+  [Schema.Record(Schema.String, Schema.Any)],
+)
+
+const Probability = Schema.Number.check(Schema.isBetween({ minimum: 0, maximum: 1 }))
+const NoulAnswer = Schema.Struct({ type: Schema.Literal("noul"), noul: Probability })
+const Choice = Schema.Struct({
+  type: Schema.Literal("choice"),
+  choice: Schema.String,
+  probabilities: Schema.Record(Schema.String, Probability),
+  confidence: Schema.optional(Probability),
+})
+const Score = Schema.Struct({
+  type: Schema.Literal("score"),
+  score: Schema.Number,
+  probabilities: Schema.Record(Schema.String, Probability),
+  legend: Schema.optional(Schema.Record(Schema.String, Schema.Json)),
+  confidence: Schema.optional(Probability),
+})
+const NativeUsage = Schema.Struct({
+  input_tokens: Schema.optional(Schema.Number),
+  output_tokens: Schema.optional(Schema.Number),
+})
+
+const encode = Schema.encodeUnknownEffect(Schema.fromJsonString(Request))
+const exact = (x: Readonly<Record<string, unknown>>, keys: ReadonlyArray<string>) =>
+  Object.keys(x).length === keys.length && keys.every((key) => Object.hasOwn(x, key))
+
+export interface ModelInput {
+  readonly id: string | ModelID
+  readonly provider: string
+  readonly providerMetadataKey: string
+  readonly auth: AuthDefinition
+  readonly baseURL: string
+  readonly headers?: Record<string, string>
+  readonly http?: HttpOptions
+}
+
+export const model = (cfg: ModelInput) => {
+  const route: EvaluationRoute = {
+    id: "system-one",
+    evaluate: (req, send) =>
+      Effect.gen(function* () {
+        const url = new URL(`${cfg.baseURL.replace(/\/$/, "")}/systemone`)
+        Object.entries(req.http?.query ?? {}).forEach(([key, value]) => url.searchParams.set(key, value))
+        const body = yield* encode({
+          ...mergeJsonRecords(req.options, req.http?.body),
+          model: req.model.id,
+          state: req.state,
+          questions: Object.fromEntries(
+            Object.entries(req.questions).map(([id, x]) => [id, x.type === "boolean" ? { ...x, type: "noul" } : x]),
+          ),
+        }).pipe(
+          Effect.mapError(
+            (cause) => new AIError({ reason: new InvalidRequestError({ message: cause.message, cause }) }),
+          ),
+        )
+        const headers = yield* Auth.toEffect(cfg.auth)({
+          request: req,
+          method: "POST",
+          url: url.toString(),
+          body,
+          headers: Headers.fromInput({ ...cfg.headers, ...req.http?.headers }),
+        })
+        const res = yield* send(
+          HttpClientRequest.post(url).pipe(
+            HttpClientRequest.setHeaders(headers),
+            HttpClientRequest.bodyText(body, "application/json"),
+          ),
+        )
+        const http = new HttpContext({ url: res.request.url, status: res.status, headers: res.headers })
+        const fail = (message: string, cause: unknown, body?: string) =>
+          new AIError({ reason: new InvalidProviderOutputError({ route: route.id, message, body, http, cause }) })
+        const text = yield* res.text.pipe(
+          Effect.mapError((cause) => fail("Failed to read the System One response", cause)),
+        )
+        const entries = Object.entries(req.questions)
+        const output = Schema.Struct({
+          model: Schema.String,
+          answers: Schema.Struct(
+            Object.fromEntries(
+              entries.map(([id, question]) => {
+                if (question.type === "boolean") return [id, NoulAnswer]
+                if (question.type === "choice") {
+                  const keys = Object.keys(question.criteria)
+                  return [
+                    id,
+                    Choice.pipe(
+                      Schema.refine(
+                        (x): x is typeof x =>
+                          Object.hasOwn(question.criteria, x.choice) && exact(x.probabilities, keys),
+                        { message: `Question "${id}" returned an invalid choice answer` },
+                      ),
+                    ),
+                  ]
+                }
+                const keys = question.criteria.map((_, index) => String(index))
+                return [
+                  id,
+                  Score.pipe(
+                    Schema.refine(
+                      (x): x is typeof x =>
+                        x.score >= 0 && x.score <= question.criteria.length - 1 && exact(x.probabilities, keys),
+                      { message: `Question "${id}" returned an invalid score answer` },
+                    ),
+                  ),
+                ]
+              }),
+            ) as Record<string, Schema.Codec<unknown>>,
+          ),
+          usage: Schema.optional(NativeUsage),
+        })
+        const data = yield* Schema.decodeUnknownEffect(Schema.fromJsonString(output))(text).pipe(
+          Effect.mapError((cause) => fail("System One returned an invalid response", cause, text)),
+        )
+
+        const confidence: Record<string, number> = {}
+        const legend: Record<string, Record<string, Schema.Json>> = {}
+        const answers = Object.fromEntries(
+          entries.map(([id, question]) => {
+            const answer = data.answers[id]
+            if (question.type === "boolean")
+              return [
+                id,
+                { type: "boolean", probability: (answer as typeof NoulAnswer.Type).noul } satisfies BooleanAnswer,
+              ]
+            if (question.type === "choice") {
+              const value = answer as typeof Choice.Type
+              if (value.confidence !== undefined) confidence[id] = value.confidence
+              return [
+                id,
+                { type: "choice", choice: value.choice, probabilities: value.probabilities } satisfies ChoiceAnswer,
+              ]
+            }
+            const value = answer as typeof Score.Type
+            if (value.confidence !== undefined) confidence[id] = value.confidence
+            if (value.legend !== undefined) legend[id] = value.legend
+            return [id, { type: "score", score: value.score, probabilities: value.probabilities } satisfies ScoreAnswer]
+          }),
+        )
+        const meta = {
+          ...(Object.keys(confidence).length === 0 ? {} : { confidence }),
+          ...(Object.keys(legend).length === 0 ? {} : { legend }),
+        }
+        return new EvaluationResponse({
+          model: ModelID.make(data.model),
+          answers,
+          usage: data.usage
+            ? new Usage({
+                inputTokens: data.usage.input_tokens,
+                outputTokens: data.usage.output_tokens,
+                totalTokens:
+                  data.usage.input_tokens === undefined && data.usage.output_tokens === undefined
+                    ? undefined
+                    : (data.usage.input_tokens ?? 0) + (data.usage.output_tokens ?? 0),
+                providerMetadata: { [cfg.providerMetadataKey]: data.usage },
+              })
+            : undefined,
+          rounding: new EvaluationRounding({ probabilityDecimals: 2, scoreDecimals: 2 }),
+          providerMetadata: Object.keys(meta).length === 0 ? undefined : { [cfg.providerMetadataKey]: meta },
+        }) as EvaluationResponseFor<typeof req.questions>
+      }),
+  }
+  return EvaluationModel.make({ id: cfg.id, provider: cfg.provider, route, http: cfg.http })
+}
+
+export const SystemOne = { model } as const
@@ -38,23 +38,13 @@ export type Settings = ProviderPackage.Settings &

 const fromRequest = Effect.fn("GoogleVertex.fromRequest")(function* (request: LLMRequest) {
  const { serviceTier: _, ...body } = yield* Gemini.protocol.body.from(request)
-  // Vertex's native REST schema rejects `id` on FunctionCall/FunctionResponse parts with HTTP 400,
-  // unlike AI Studio, so history minted there cannot be lowered verbatim.
-  const contents = body.contents.map((content) => ({
-    ...content,
-    parts: (content.parts ?? []).map((part) => {
-      if ("functionCall" in part) return { ...part, functionCall: { ...part.functionCall, id: undefined } }
-      if ("functionResponse" in part) return { ...part, functionResponse: { ...part.functionResponse, id: undefined } }
-      return part
-    }),
-  }))
  const value = request.providerOptions?.labels
  const labels = ProviderShared.isRecord(value)
    ? Object.fromEntries(
        Object.entries(value).filter((entry): entry is [string, string] => typeof entry[1] === "string"),
      )
    : undefined
-  return { ...body, contents, labels }
+  return { ...body, labels }
 })

 const protocol = {
@@ -24,8 +24,10 @@ export * as Moonshot from "./moonshot.js"
 export * as OpenAI from "./openai.js"
 export * as OpenAICompatible from "./openai-compatible.js"
 export * as OpenAICompatibleResponses from "./openai-compatible-responses.js"
+export * as OpenCodeZen from "./opencode-zen.js"
 export * as OpenRouter from "./openrouter.js"
 export * as TogetherAI from "./togetherai.js"
+export * as TypeSafeAI from "./typesafe-ai.js"
 export * as XAI from "./xai.js"
 export * as ZAI from "./zai.js"
 export * as ZAICodingPlan from "./zai-coding-plan.js"
@@ -0,0 +1,31 @@
+import { HttpOptions, ProviderID, type ModelID } from "../schema/index.js"
+import { AuthOptions, type ProviderAuthOption } from "../route/auth-options.js"
+import { SystemOne } from "../experimental/system-one.js"
+
+export const id = ProviderID.make("opencode")
+const baseURL = "https://opencode.ai/zen/v1"
+
+export type Options = ProviderAuthOption<"optional"> & {
+  readonly baseURL?: string
+  readonly headers?: Record<string, string>
+  readonly http?: HttpOptions.Input
+}
+
+export const configure = (input: Options = {}) => {
+  const evaluation = (modelID: string | ModelID) =>
+    SystemOne.model({
+      id: modelID,
+      provider: id,
+      providerMetadataKey: "opencode",
+      auth: AuthOptions.bearer(input, "OPENCODE_API_KEY"),
+      baseURL: input.baseURL ?? baseURL,
+      headers: input.headers,
+      http: input.http === undefined ? undefined : HttpOptions.make(input.http),
+    })
+  return { id, experimental: { evaluation }, configure }
+}
+
+export const provider = configure()
+export const experimental = provider.experimental
+
+export * as OpenCodeZen from "./opencode-zen.js"
@@ -0,0 +1,31 @@
+import { HttpOptions, ProviderID, type ModelID } from "../schema/index.js"
+import { AuthOptions, type ProviderAuthOption } from "../route/auth-options.js"
+import { SystemOne } from "../experimental/system-one.js"
+
+export const id = ProviderID.make("typesafe-ai")
+const baseURL = "https://api.typesafe.ai/v1"
+
+export type Options = ProviderAuthOption<"optional"> & {
+  readonly baseURL?: string
+  readonly headers?: Record<string, string>
+  readonly http?: HttpOptions.Input
+}
+
+export const configure = (input: Options = {}) => {
+  const evaluation = (modelID: string | ModelID) =>
+    SystemOne.model({
+      id: modelID,
+      provider: id,
+      providerMetadataKey: "typesafe",
+      auth: AuthOptions.bearer(input, "TYPESAFE_API_KEY"),
+      baseURL: input.baseURL ?? baseURL,
+      headers: input.headers,
+      http: input.http === undefined ? undefined : HttpOptions.make(input.http),
+    })
+  return { id, experimental: { evaluation }, configure }
+}
+
+export const provider = configure()
+export const experimental = provider.experimental
+
+export * as TypeSafeAI from "./typesafe-ai.js"
@@ -0,0 +1,173 @@
+import { describe, expect } from "bun:test"
+import { Effect, Layer } from "effect"
+import { HttpClientRequest } from "effect/unstable/http"
+import { Evaluation, EvaluationClient } from "../src/experimental.js"
+import { OpenCodeZen, TypeSafeAI } from "../src/providers.js"
+import { it } from "./lib/effect.js"
+import { dynamicResponse } from "./lib/http.js"
+
+describe("experimental Evaluation", () => {
+  it.effect("evaluates typed questions through System One", () =>
+    Effect.gen(function* () {
+      const response = yield* Evaluation.evaluate({
+        model: TypeSafeAI.configure({
+          apiKey: "test",
+          baseURL: "https://typesafe.test/v1/",
+          headers: { "x-default": "yes" },
+          http: { body: { deployment: "test" }, query: { api: "v1" } },
+        }).experimental.evaluation("jev-latest"),
+        state: { ticket: "Please refund the duplicate charge." },
+        questions: {
+          department: {
+            type: "choice",
+            instructions: "Which team should handle this?",
+            criteria: { billing: "Payments and refunds", technical: "Bugs and outages" },
+          },
+          urgency: {
+            type: "score",
+            instructions: "How urgent is this?",
+            criteria: ["Can wait", "Needs attention", "Blocking"],
+          },
+          refund: { type: "boolean", instructions: "Is the customer asking for a refund?" },
+        },
+        options: { trace: { enabled: true } },
+        http: { body: { request_metadata: "value" }, headers: { "x-request": "yes" }, query: { trace: "1" } },
+      })
+
+      expect(response.model).toBe("jev-1.13.0")
+      expect(response.answers.department).toEqual({
+        type: "choice",
+        choice: "billing",
+        probabilities: { billing: 0.9, technical: 0.1 },
+      })
+      expect(response.answers.urgency).toEqual({
+        type: "score",
+        score: 1.2,
+        probabilities: { "0": 0, "1": 0.8, "2": 0.2 },
+      })
+      expect(response.answers.refund).toEqual({ type: "boolean", probability: 0.97 })
+      expect(response.usage?.totalTokens).toBe(36)
+      expect(response.providerMetadata).toEqual({
+        typesafe: {
+          confidence: { department: 0.8, urgency: 0.6 },
+          legend: { urgency: { "0": "Can wait", "1": "Needs attention", "2": "Blocking" } },
+        },
+      })
+    }).pipe(
+      Effect.provide(
+        EvaluationClient.layer.pipe(
+          Layer.provide(
+            dynamicResponse((input) =>
+              Effect.gen(function* () {
+                const request = yield* HttpClientRequest.toWeb(input.request).pipe(Effect.orDie)
+                expect(request.url).toBe("https://typesafe.test/v1/systemone?api=v1&trace=1")
+                expect(request.headers.get("authorization")).toBe("Bearer test")
+                expect(request.headers.get("x-default")).toBe("yes")
+                expect(request.headers.get("x-request")).toBe("yes")
+                expect(JSON.parse(input.text)).toEqual({
+                  deployment: "test",
+                  request_metadata: "value",
+                  trace: { enabled: true },
+                  model: "jev-latest",
+                  state: { ticket: "Please refund the duplicate charge." },
+                  questions: {
+                    department: {
+                      type: "choice",
+                      instructions: "Which team should handle this?",
+                      criteria: { billing: "Payments and refunds", technical: "Bugs and outages" },
+                    },
+                    urgency: {
+                      type: "score",
+                      instructions: "How urgent is this?",
+                      criteria: ["Can wait", "Needs attention", "Blocking"],
+                    },
+                    refund: { type: "noul", instructions: "Is the customer asking for a refund?" },
+                  },
+                })
+                return input.respond(
+                  JSON.stringify({
+                    model: "jev-1.13.0",
+                    answers: {
+                      department: {
+                        type: "choice",
+                        choice: "billing",
+                        probabilities: { billing: 0.9, technical: 0.1 },
+                        confidence: 0.8,
+                      },
+                      urgency: {
+                        type: "score",
+                        score: 1.2,
+                        probabilities: { "0": 0, "1": 0.8, "2": 0.2 },
+                        legend: { "0": "Can wait", "1": "Needs attention", "2": "Blocking" },
+                        confidence: 0.6,
+                      },
+                      refund: { type: "noul", noul: 0.97 },
+                    },
+                    usage: { input_tokens: 30, output_tokens: 6 },
+                  }),
+                  { headers: { "content-type": "application/json" } },
+                )
+              }),
+            ),
+          ),
+        ),
+      ),
+    ),
+  )
+
+  it.effect("configures the OpenCode Zen System One endpoint", () =>
+    Evaluation.evaluate({
+      model: OpenCodeZen.configure({ apiKey: "zen-key", baseURL: "https://zen.test/v1" }).experimental.evaluation(
+        "jev-1.13",
+      ),
+      state: "hello",
+      questions: { greeting: { type: "boolean", instructions: "Is this a greeting?" } },
+    }).pipe(
+      Effect.tap((response) =>
+        Effect.sync(() => {
+          expect(response.answers.greeting.probability).toBe(0.99)
+          expect(response.usage?.providerMetadata).toEqual({
+            opencode: { input_tokens: 10, output_tokens: 2 },
+          })
+        }),
+      ),
+      Effect.provide(
+        EvaluationClient.layer.pipe(
+          Layer.provide(
+            dynamicResponse((input) => {
+              expect(input.request.url).toBe("https://zen.test/v1/systemone")
+              expect(input.request.headers.authorization).toBe("Bearer zen-key")
+              return Effect.succeed(
+                input.respond(
+                  JSON.stringify({
+                    model: "jev-1.13.0",
+                    answers: { greeting: { type: "noul", noul: 0.99 } },
+                    usage: { input_tokens: 10, output_tokens: 2 },
+                  }),
+                  { headers: { "content-type": "application/json" } },
+                ),
+              )
+            }),
+          ),
+        ),
+      ),
+    ),
+  )
+
+  it.effect("rejects malformed questions before network I/O", () =>
+    Effect.gen(function* () {
+      const error = yield* Evaluation.evaluate({
+        model: TypeSafeAI.experimental.evaluation("jev-latest"),
+        state: "hello",
+        questions: { score: { type: "score", instructions: "How much?", criteria: ["only"] } },
+      }).pipe(Effect.flip)
+      expect(error.reason._tag).toBe("InvalidRequest")
+    }).pipe(
+      Effect.provide(
+        EvaluationClient.layer.pipe(
+          Layer.provide(dynamicResponse(() => Effect.die("invalid evaluation reached the network"))),
+        ),
+      ),
+    ),
+  )
+})
@@ -0,0 +1,60 @@
+import { Effect } from "effect"
+import { Evaluation, EvaluationClient, EvaluationModel, type EvaluationRoute } from "../src/experimental.js"
+import type { Service } from "../src/experimental/evaluation-client.js"
+import { OpenCodeZen, TypeSafeAI } from "../src/providers.js"
+
+type Requirements<T> = T extends Effect.Effect<infer _A, infer _E, infer R> ? R : never
+type Success<T> = T extends Effect.Effect<infer A, infer _E, infer _R> ? A : never
+type Equal<A, B> = [A, B] extends [B, A] ? true : false
+type Assert<T extends true> = T
+
+const model = TypeSafeAI.configure({ apiKey: "test" }).experimental.evaluation("jev-latest")
+const request = Evaluation.request({
+  model,
+  state: { ticket: "refund" },
+  questions: {
+    topic: {
+      type: "choice",
+      instructions: "Which team?",
+      criteria: { billing: null, support: { includes: ["help"] } },
+    },
+    severity: { type: "score", instructions: "How severe?", criteria: ["Low", "High"] },
+    refund: { type: "boolean", instructions: "Refund?" },
+  },
+})
+
+const result = EvaluationClient.evaluate(request)
+type Result = Success<typeof result>
+type Choice = Assert<Equal<Result["answers"]["topic"]["choice"], "billing" | "support">>
+type ClientRequirements = Assert<Equal<Requirements<typeof result>, Service>>
+void (true satisfies Choice)
+void (true satisfies ClientRequirements)
+
+Effect.gen(function* () {
+  const response = yield* Evaluation.evaluate({
+    model: OpenCodeZen.experimental.evaluation("jev-1.13"),
+    state: ["hello"],
+    questions: { greeting: { type: "boolean", instructions: "Greeting?" } },
+  })
+  response.answers.greeting.probability satisfies number
+  // @ts-expect-error Boolean answers do not contain a selected choice.
+  response.answers.greeting.choice
+  // @ts-expect-error Unknown question IDs are not exposed.
+  response.answers.missing
+})
+
+declare const route: EvaluationRoute<{ readonly temperature?: number }>
+const custom = EvaluationModel.make({ id: "custom", provider: "custom", route })
+Evaluation.evaluate({
+  model: custom,
+  state: "hello",
+  questions: { ok: { type: "boolean", instructions: "OK?" } },
+  options: { temperature: 0.5 },
+})
+// @ts-expect-error Selected evaluation models retain their request option types.
+Evaluation.evaluate({
+  model: custom,
+  state: "hello",
+  questions: { ok: { type: "boolean", instructions: "OK?" } },
+  options: { temperature: "high" },
+})
@@ -8,9 +8,11 @@ import {
  CloudflareWorkersAI,
  DeepSeek,
  Fireworks,
+  OpenCodeZen,
  OpenAI,
  OpenAICompatible,
  OpenRouter,
+  TypeSafeAI,
  XAI,
 } from "@opencode/ai/providers"
 import {
@@ -23,6 +25,7 @@ import {
 } from "@opencode/ai/protocols"
 import * as AnthropicMessages from "@opencode/ai/protocols/anthropic-messages"
 import { TestLLM } from "@opencode/ai/testing"
+import { Evaluation, EvaluationClient } from "@opencode/ai/experimental"

 describe("public exports", () => {
  test("root exposes app-facing runtime APIs", () => {
@@ -37,6 +40,9 @@ describe("public exports", () => {
    expect(TestLLM.layer).toBeFunction()
    expect(TestLLM.testLayer).toBeFunction()
    expect(TestLLM.Test.of).toBeFunction()
+    expect(Evaluation.evaluate).toBeFunction()
+    expect(EvaluationClient.layer).toBeDefined()
+    expect(EvaluationClient.fetchLayer).toBeDefined()
  })

  test("route barrel exposes route-authoring APIs", () => {
@@ -66,6 +72,8 @@ describe("public exports", () => {
    expect(CloudflareWorkersAI.configure).toBeFunction()
    expect(CloudflareWorkersAI.configure({ accountId: "fixture", apiKey: "fixture" }).model).toBeFunction()
    expect(OpenRouter.model).toBeFunction()
+    expect(TypeSafeAI.experimental.evaluation).toBeFunction()
+    expect(OpenCodeZen.experimental.evaluation).toBeFunction()
    expect(XAI.model).toBeFunction()
    expect(XAI.provider.responses).toBe(XAI.responses)
    expect(XAI.provider.chat).toBe(XAI.chat)
@@ -1,9 +1,13 @@
 {
  "version": 1,
  "metadata": {
-    "tags": ["prefix:google-vertex", "provider:google-vertex", "protocol:gemini"],
+    "tags": [
+      "prefix:google-vertex",
+      "provider:google-vertex",
+      "protocol:gemini"
+    ],
    "name": "google-vertex/calls-a-tool",
-    "recordedAt": "2026-08-23T17:21:51.036Z"
+    "recordedAt": "2026-09-22T03:46:29.725Z"
  },
  "interactions": [
    {
@@ -21,7 +25,7 @@
        "headers": {
          "content-type": "text/event-stream"
        },
-        "body": "data: {\"candidates\": [{\"content\": {\"role\": \"model\",\"parts\": [{\"functionCall\": {\"name\": \"lookup_weather\",\"args\": {\"city\": \"Paris\"},\"id\": \"call_425130\"},\"thoughtSignature\": \"AY89a1+1fXnLgYhHMuN3Ak6LBhT6PcrYOW7iPav4LfsacvG/Z6l1yJ+AsU7vWhFj/JyPIbsJJQ+GjohM9sCIZ6nqUOIg3reo/7osmrCvFrVHedTHQcwiPzoz2Kp3gb+uWjFAXxk1EX4IRAKcu0ox1W/Z9PpuZvHkTerGO2a82e02N6MAF1YhhtbXFvSdqLRih2Os68rdOk5/Bcld7ol8qUgeyIZ3CtI3OJ5jwRcD8LjvK33A7ZFzH5Bxp/peUmXvqnu5iNhnGBxZaJy/vupCtxRZxjaS+ojG0/UhyrnRiKIpbzQ0FBkxePPn8GCX/LOe2y3GUc98co8lN8OOuCd9ZmEdx5AjHmQkPO9fAV9SxG6Bda6SDWVL8o/Uz3WSQYoUEfAdoajEWIBvcisoeCJjb7zgmRRZ9VQSPl3RXj5LFRvX8jn0YKV1CahYbc24jA==\"}]}}],\"usageMetadata\": {\"trafficType\": \"ON_DEMAND\"},\"modelVersion\": \"gemini-3.5-flash\",\"createTime\": \"2026-08-23T17:21:50.308576Z\",\"responseId\": \"LiyLauDqErCErb8Pj8aWkAs\"}\r\n\r\ndata: {\"candidates\": [{\"content\": {\"role\": \"model\",\"parts\": [{\"text\": \"\"}]},\"finishReason\": \"STOP\"}],\"usageMetadata\": {\"promptTokenCount\": 39,\"candidatesTokenCount\": 16,\"totalTokenCount\": 102,\"trafficType\": \"ON_DEMAND\",\"promptTokensDetails\": [{\"modality\": \"TEXT\",\"tokenCount\": 39}],\"candidatesTokensDetails\": [{\"modality\": \"TEXT\",\"tokenCount\": 16}],\"thoughtsTokenCount\": 47},\"modelVersion\": \"gemini-3.5-flash\",\"createTime\": \"2026-08-23T17:21:50.308576Z\",\"responseId\": \"LiyLauDqErCErb8Pj8aWkAs\"}\r\n\r\n"
+        "body": "data: {\"candidates\": [{\"content\": {\"role\": \"model\",\"parts\": [{\"functionCall\": {\"name\": \"lookup_weather\",\"args\": {\"city\": \"Paris\"},\"id\": \"call_28936\"},\"thoughtSignature\": \"AY89a1/MVeBxtwu9l/96clFobOrrd7Q5MTf5o8/A22fc++1EsFYVeCFx9WCGmJ+D3yW3FWlRXKtJECYfprSoxixCSOYBNiV9g8/IkejbAxF26k1vxTsHkoqts0O2s8GqqBSRAavJfKQ/taTRbPuIq+b+RKZ8SDJFoWDnFjXpdS5S164uJTjmgs4ALd8oB1oQRycMsTbAY51TmkcNUnhARpjKQfqiizz4KfSRFjx7xDnza0v4jj73m2GV86eLDhVT7trIT+Dl5DsJt6RBLOE2Amse54mcpIbsYaANlY1YDU6FKuUBqnuwpl0OfhMXwWuYMogv1tH/0rTXsqNwmHyt/b9ZZXqYCdFXpMGt8udmoZ0d\"}]}}],\"usageMetadata\": {\"trafficType\": \"ON_DEMAND\"},\"modelVersion\": \"gemini-3.5-flash\",\"createTime\": \"2026-09-22T03:46:28.953809Z\",\"responseId\": \"FPqxatGbOsSorb8PtY2z8Q4\"}\r\n\r\ndata: {\"candidates\": [{\"content\": {\"role\": \"model\",\"parts\": [{\"text\": \"\"}]},\"finishReason\": \"STOP\"}],\"usageMetadata\": {\"promptTokenCount\": 39,\"candidatesTokenCount\": 16,\"totalTokenCount\": 93,\"trafficType\": \"ON_DEMAND\",\"promptTokensDetails\": [{\"modality\": \"TEXT\",\"tokenCount\": 39}],\"candidatesTokensDetails\": [{\"modality\": \"TEXT\",\"tokenCount\": 16}],\"thoughtsTokenCount\": 38},\"modelVersion\": \"gemini-3.5-flash\",\"createTime\": \"2026-09-22T03:46:28.953809Z\",\"responseId\": \"FPqxatGbOsSorb8PtY2z8Q4\"}\r\n\r\n"
      }
    }
  ]
@@ -1,9 +1,13 @@
 {
  "version": 1,
  "metadata": {
-    "tags": ["prefix:google-vertex", "provider:google-vertex", "protocol:gemini"],
+    "tags": [
+      "prefix:google-vertex",
+      "provider:google-vertex",
+      "protocol:gemini"
+    ],
    "name": "google-vertex/continues-after-a-tool-result",
-    "recordedAt": "2026-08-23T17:21:51.853Z"
+    "recordedAt": "2026-09-22T03:46:30.691Z"
  },
  "interactions": [
    {
@@ -14,14 +18,14 @@
        "headers": {
          "content-type": "application/json"
        },
-        "body": "{\"contents\":[{\"role\":\"user\",\"parts\":[{\"text\":\"What is the weather in Paris?\"}]},{\"role\":\"model\",\"parts\":[{\"functionCall\":{\"name\":\"lookup_weather\",\"args\":{\"city\":\"Paris\"}},\"thoughtSignature\":\"skip_thought_signature_validator\"}]},{\"role\":\"user\",\"parts\":[{\"functionResponse\":{\"name\":\"lookup_weather\",\"response\":{\"name\":\"lookup_weather\",\"content\":\"18C, light rain\"}}}]}],\"tools\":[{\"functionDeclarations\":[{\"name\":\"lookup_weather\",\"description\":\"Look up the current weather for a city\",\"parameters\":{\"required\":[\"city\"],\"type\":\"object\",\"properties\":{\"city\":{\"type\":\"string\"}}}}]}]}"
+        "body": "{\"contents\":[{\"role\":\"user\",\"parts\":[{\"text\":\"What is the weather in Paris?\"}]},{\"role\":\"model\",\"parts\":[{\"functionCall\":{\"id\":\"call_paris_1\",\"name\":\"lookup_weather\",\"args\":{\"city\":\"Paris\"}},\"thoughtSignature\":\"skip_thought_signature_validator\"}]},{\"role\":\"user\",\"parts\":[{\"functionResponse\":{\"id\":\"call_paris_1\",\"name\":\"lookup_weather\",\"response\":{\"name\":\"lookup_weather\",\"content\":\"18C, light rain\"}}}]}],\"tools\":[{\"functionDeclarations\":[{\"name\":\"lookup_weather\",\"description\":\"Look up the current weather for a city\",\"parameters\":{\"required\":[\"city\"],\"type\":\"object\",\"properties\":{\"city\":{\"type\":\"string\"}}}}]}]}"
      },
      "response": {
        "status": 200,
        "headers": {
          "content-type": "text/event-stream"
        },
-        "body": "data: {\"candidates\": [{\"content\": {\"role\": \"model\",\"parts\": [{\"text\": \"The weather in Paris is currently 18°C with light rain.\"}]}}],\"usageMetadata\": {\"trafficType\": \"ON_DEMAND\"},\"modelVersion\": \"gemini-3.5-flash\",\"createTime\": \"2026-08-23T17:21:51.220919Z\",\"responseId\": \"LyyLave9DbWnrb8P1IjLmQQ\"}\r\n\r\ndata: {\"candidates\": [{\"content\": {\"role\": \"model\",\"parts\": [{\"text\": \"\",\"thoughtSignature\": \"AY89a197c+fpHJftPtcufnqMAyoRQKVEQK+KeG+RVHVx2wKil3L4jP4YWvfVbcuOFr2jio4Kre/hCrDANAoMFSvaZrdaPeo1b5bXQSmJKMH03yM5M6q6ME6JiBvXym143U4exIde4UbOh2tMeyXMvB3aWxcavIHd78g5G5QPLreo6A3LO5871cYYVeRwteY+/zbEdqfaAq1hlk6WYpWkNljYpjMyKwr15YC8rFLh3HYayS9tTN++GGrk/reZn6C3OEPlzPou/pXRATzcEAGVl/TW\"}]},\"finishReason\": \"STOP\"}],\"usageMetadata\": {\"promptTokenCount\": 59,\"candidatesTokenCount\": 15,\"totalTokenCount\": 98,\"trafficType\": \"ON_DEMAND\",\"promptTokensDetails\": [{\"modality\": \"TEXT\",\"tokenCount\": 59}],\"candidatesTokensDetails\": [{\"modality\": \"TEXT\",\"tokenCount\": 15}],\"thoughtsTokenCount\": 24},\"modelVersion\": \"gemini-3.5-flash\",\"createTime\": \"2026-08-23T17:21:51.220919Z\",\"responseId\": \"LyyLave9DbWnrb8P1IjLmQQ\"}\r\n\r\n"
+        "body": "data: {\"candidates\": [{\"content\": {\"role\": \"model\",\"parts\": [{\"text\": \"The weather\"}]}}],\"usageMetadata\": {\"trafficType\": \"ON_DEMAND\"},\"modelVersion\": \"gemini-3.5-flash\",\"createTime\": \"2026-09-22T03:46:29.830958Z\",\"responseId\": \"Ffqxau7bMoCOrb8P_Iu5sA0\"}\r\n\r\ndata: {\"candidates\": [{\"content\": {\"role\": \"model\",\"parts\": [{\"text\": \" in Paris is currently 18°C with light rain.\"}]}}],\"usageMetadata\": {\"trafficType\": \"ON_DEMAND\"},\"modelVersion\": \"gemini-3.5-flash\",\"createTime\": \"2026-09-22T03:46:29.830958Z\",\"responseId\": \"Ffqxau7bMoCOrb8P_Iu5sA0\"}\r\n\r\ndata: {\"candidates\": [{\"content\": {\"role\": \"model\",\"parts\": [{\"text\": \"\",\"thoughtSignature\": \"AY89a18aVI8Uxr2VaOI822u0DyuQdy4B00uhLnjqYb5Qb6Mkscccm018knLtYThB5UX8dRv1VFsORSQ0Qo6Gx9RCng2AK9EPce7p\"}]},\"finishReason\": \"STOP\"}],\"usageMetadata\": {\"promptTokenCount\": 59,\"candidatesTokenCount\": 15,\"totalTokenCount\": 74,\"trafficType\": \"ON_DEMAND\",\"promptTokensDetails\": [{\"modality\": \"TEXT\",\"tokenCount\": 59}],\"candidatesTokensDetails\": [{\"modality\": \"TEXT\",\"tokenCount\": 15}]},\"modelVersion\": \"gemini-3.5-flash\",\"createTime\": \"2026-09-22T03:46:29.830958Z\",\"responseId\": \"Ffqxau7bMoCOrb8P_Iu5sA0\"}\r\n\r\n"
      }
    }
  ]
@@ -1,9 +1,13 @@
 {
  "version": 1,
  "metadata": {
-    "tags": ["prefix:google-vertex", "provider:google-vertex", "protocol:gemini"],
+    "tags": [
+      "prefix:google-vertex",
+      "provider:google-vertex",
+      "protocol:gemini"
+    ],
    "name": "google-vertex/streams-text",
-    "recordedAt": "2026-08-23T17:21:50.112Z"
+    "recordedAt": "2026-09-22T03:46:28.840Z"
  },
  "interactions": [
    {
@@ -21,7 +25,7 @@
        "headers": {
          "content-type": "text/event-stream"
        },
-        "body": "data: {\"candidates\": [{\"content\": {\"role\": \"model\",\"parts\": [{\"text\": \"Hello\"}]}}],\"usageMetadata\": {\"trafficType\": \"ON_DEMAND\"},\"modelVersion\": \"gemini-3.5-flash\",\"createTime\": \"2026-08-23T17:21:48.528714Z\",\"responseId\": \"LCyLasqiIO6crb8P1sDboQc\"}\r\n\r\ndata: {\"candidates\": [{\"content\": {\"role\": \"model\",\"parts\": [{\"text\": \"\",\"thoughtSignature\": \"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\"}]},\"finishReason\": \"STOP\"}],\"usageMetadata\": {\"promptTokenCount\": 7,\"candidatesTokenCount\": 1,\"totalTokenCount\": 150,\"trafficType\": \"ON_DEMAND\",\"promptTokensDetails\": [{\"modality\": \"TEXT\",\"tokenCount\": 7}],\"candidatesTokensDetails\": [{\"modality\": \"TEXT\",\"tokenCount\": 1}],\"thoughtsTokenCount\": 142},\"modelVersion\": \"gemini-3.5-flash\",\"createTime\": \"2026-08-23T17:21:48.528714Z\",\"responseId\": \"LCyLasqiIO6crb8P1sDboQc\"}\r\n\r\n"
+        "body": "data: {\"candidates\": [{\"content\": {\"role\": \"model\",\"parts\": [{\"text\": \"Hello\"}]}}],\"usageMetadata\": {\"trafficType\": \"ON_DEMAND\"},\"modelVersion\": \"gemini-3.5-flash\",\"createTime\": \"2026-09-22T03:46:26.748531Z\",\"responseId\": \"EvqxavPXLbqerb8P1eSViQs\"}\r\n\r\ndata: {\"candidates\": [{\"content\": {\"role\": \"model\",\"parts\": [{\"text\": \"\",\"thoughtSignature\": \"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\"}]},\"finishReason\": \"STOP\"}],\"usageMetadata\": {\"promptTokenCount\": 7,\"candidatesTokenCount\": 1,\"totalTokenCount\": 285,\"trafficType\": \"ON_DEMAND\",\"promptTokensDetails\": [{\"modality\": \"TEXT\",\"tokenCount\": 7}],\"candidatesTokensDetails\": [{\"modality\": \"TEXT\",\"tokenCount\": 1}],\"thoughtsTokenCount\": 277},\"modelVersion\": \"gemini-3.5-flash\",\"createTime\": \"2026-09-22T03:46:26.748531Z\",\"responseId\": \"EvqxavPXLbqerb8P1eSViQs\"}\r\n\r\n"
      }
    }
  ]
@@ -0,0 +1,33 @@
+{
+  "version": 1,
+  "metadata": {
+    "model": "jev-1.13-free",
+    "tags": [
+      "prefix:opencode-zen-evaluation",
+      "provider:opencode",
+      "protocol:system-one"
+    ],
+    "name": "opencode-zen-evaluation/evaluates-choice-score-and-boolean-questions",
+    "recordedAt": "2026-09-22T03:44:57.511Z"
+  },
+  "interactions": [
+    {
+      "transport": "http",
+      "request": {
+        "method": "POST",
+        "url": "https://opencode.ai/zen/v1/systemone",
+        "headers": {
+          "content-type": "application/json"
+        },
+        "body": "{\"model\":\"jev-1.13-free\",\"state\":\"I was charged twice for the same invoice. Please refund the duplicate payment today.\",\"questions\":{\"department\":{\"type\":\"choice\",\"instructions\":\"Which team should handle this support request?\",\"criteria\":{\"billing\":\"Payments, invoices, refunds, or failed charges\",\"technical\":\"Bugs, outages, or integrations\",\"sales\":\"Pricing, upgrades, or new accounts\"}},\"urgency\":{\"type\":\"score\",\"instructions\":\"How urgent is this support request?\",\"criteria\":[\"Can wait for normal support\",\"Needs prompt attention\",\"Actively blocking revenue\"]},\"refund\":{\"type\":\"noul\",\"instructions\":\"Is the customer asking for a refund?\"}}}"
+      },
+      "response": {
+        "status": 200,
+        "headers": {
+          "content-type": "application/json"
+        },
+        "body": "{\"model\":\"jev-1.13-free\",\"answers\":{\"department\":{\"type\":\"choice\",\"choice\":\"billing\",\"confidence\":1,\"probabilities\":{\"technical\":0,\"sales\":0,\"billing\":1}},\"urgency\":{\"type\":\"score\",\"score\":1.02,\"confidence\":0.95,\"legend\":{\"0\":\"Can wait for normal support\",\"1\":\"Needs prompt attention\",\"2\":\"Actively blocking revenue\"},\"probabilities\":{\"0\":0,\"1\":0.97,\"2\":0.03}},\"refund\":{\"type\":\"noul\",\"noul\":0.99}},\"usage\":{\"input_tokens\":422,\"output_tokens\":69}}"
+      }
+    }
+  ]
+}
@@ -0,0 +1,33 @@
+{
+  "version": 1,
+  "metadata": {
+    "model": "jev-latest",
+    "tags": [
+      "prefix:typesafe-evaluation",
+      "provider:typesafe-ai",
+      "protocol:system-one"
+    ],
+    "name": "typesafe-evaluation/evaluates-choice-score-and-boolean-questions",
+    "recordedAt": "2026-09-22T03:44:28.626Z"
+  },
+  "interactions": [
+    {
+      "transport": "http",
+      "request": {
+        "method": "POST",
+        "url": "https://api.typesafe.ai/v1/systemone",
+        "headers": {
+          "content-type": "application/json"
+        },
+        "body": "{\"model\":\"jev-latest\",\"state\":\"I was charged twice for the same invoice. Please refund the duplicate payment today.\",\"questions\":{\"department\":{\"type\":\"choice\",\"instructions\":\"Which team should handle this support request?\",\"criteria\":{\"billing\":\"Payments, invoices, refunds, or failed charges\",\"technical\":\"Bugs, outages, or integrations\",\"sales\":\"Pricing, upgrades, or new accounts\"}},\"urgency\":{\"type\":\"score\",\"instructions\":\"How urgent is this support request?\",\"criteria\":[\"Can wait for normal support\",\"Needs prompt attention\",\"Actively blocking revenue\"]},\"refund\":{\"type\":\"noul\",\"instructions\":\"Is the customer asking for a refund?\"}}}"
+      },
+      "response": {
+        "status": 200,
+        "headers": {
+          "content-type": "application/json"
+        },
+        "body": "{\"model\":\"jev-1.13.0\",\"answers\":{\"department\":{\"type\":\"choice\",\"choice\":\"billing\",\"confidence\":1.0,\"probabilities\":{\"billing\":1.0,\"sales\":0.0,\"technical\":0.0}},\"urgency\":{\"type\":\"score\",\"score\":1.01,\"confidence\":0.97,\"legend\":{\"0\":\"Can wait for normal support\",\"1\":\"Needs prompt attention\",\"2\":\"Actively blocking revenue\"},\"probabilities\":{\"0\":0.0,\"1\":0.98,\"2\":0.02}},\"refund\":{\"type\":\"noul\",\"noul\":0.99}},\"usage\":{\"input_tokens\":422,\"output_tokens\":69}}"
+      }
+    }
+  ]
+}
@@ -0,0 +1,79 @@
+import { describe, expect } from "bun:test"
+import { Effect } from "effect"
+import { Evaluation } from "../../src/experimental.js"
+import { OpenCodeZen, TypeSafeAI } from "../../src/providers.js"
+import { recordedTests } from "../recorded-test.js"
+
+const questions = {
+  department: {
+    type: "choice",
+    instructions: "Which team should handle this support request?",
+    criteria: {
+      billing: "Payments, invoices, refunds, or failed charges",
+      technical: "Bugs, outages, or integrations",
+      sales: "Pricing, upgrades, or new accounts",
+    },
+  },
+  urgency: {
+    type: "score",
+    instructions: "How urgent is this support request?",
+    criteria: ["Can wait for normal support", "Needs prompt attention", "Actively blocking revenue"],
+  },
+  refund: { type: "boolean", instructions: "Is the customer asking for a refund?" },
+} as const
+
+const state = "I was charged twice for the same invoice. Please refund the duplicate payment today."
+
+const typesafe = recordedTests({
+  prefix: "typesafe-evaluation",
+  provider: "typesafe-ai",
+  protocol: "system-one",
+  requires: ["TYPESAFE_API_KEY"],
+  metadata: { model: "jev-latest" },
+})
+
+const zen = recordedTests({
+  prefix: "opencode-zen-evaluation",
+  provider: "opencode",
+  protocol: "system-one",
+  requires: ["OPENCODE_API_KEY"],
+  metadata: { model: "jev-1.13-free" },
+})
+
+describe("experimental Evaluation recorded", () => {
+  typesafe.effect("evaluates choice score and boolean questions", () =>
+    assertEvaluation(
+      TypeSafeAI.configure({ apiKey: process.env.TYPESAFE_API_KEY ?? "fixture" }).experimental.evaluation("jev-latest"),
+      "typesafe",
+    ),
+  )
+
+  zen.effect("evaluates choice score and boolean questions", () =>
+    assertEvaluation(
+      OpenCodeZen.configure({ apiKey: process.env.OPENCODE_API_KEY ?? "fixture" }).experimental.evaluation(
+        "jev-1.13-free",
+      ),
+      "opencode",
+    ),
+  )
+})
+
+const assertEvaluation = (
+  model: ReturnType<typeof TypeSafeAI.experimental.evaluation>,
+  metadataKey: "typesafe" | "opencode",
+) =>
+  Effect.gen(function* () {
+    const response = yield* Evaluation.evaluate({ model, state, questions })
+    expect(response.model).toStartWith("jev-")
+    expect(response.answers.department.type).toBe("choice")
+    expect(response.answers.department.choice).toBe("billing")
+    expect(response.answers.department.probabilities?.billing).toBeGreaterThan(0.5)
+    expect(response.answers.urgency.type).toBe("score")
+    expect(response.answers.urgency.score).toBeGreaterThanOrEqual(0)
+    expect(response.answers.urgency.score).toBeLessThanOrEqual(2)
+    expect(response.answers.refund.type).toBe("boolean")
+    expect(response.answers.refund.probability).toBeGreaterThan(0.5)
+    expect(response.usage?.inputTokens).toBeGreaterThan(0)
+    expect(response.usage?.outputTokens).toBeGreaterThan(0)
+    expect(response.providerMetadata?.[metadataKey]?.confidence).toBeDefined()
+  })
@@ -114,7 +114,7 @@ describe("Google Vertex providers", () => {
    }),
  )

-  it.effect("strips function call ids Vertex does not accept from lowered bodies", () =>
+  it.effect("preserves function call ids in lowered Vertex bodies", () =>
    Effect.gen(function* () {
      const prepared = yield* compileRequest(
        LLM.request({
@@ -142,15 +142,14 @@ describe("Google Vertex providers", () => {
        }),
      )

-      expect(JSON.stringify(prepared.body.contents)).not.toContain('"id"')
      expect(prepared.body.contents).toMatchObject([
-        { role: "model", parts: [{ functionCall: { id: undefined, name: "lookup", args: { query: "weather" } } }] },
+        { role: "model", parts: [{ functionCall: { id: "call_1", name: "lookup", args: { query: "weather" } } }] },
        {
          role: "user",
          parts: [
            {
              functionResponse: {
-                id: undefined,
+                id: "call_1",
                name: "lookup",
                response: { name: "lookup", content: "sunny" },
              },
@@ -235,12 +234,23 @@ describe("Google Vertex providers", () => {
          parts: [
            { text: "Thinking.", thought: true, thoughtSignature: "reasoning_sig" },
            { text: "Checking.", thoughtSignature: "text_sig" },
-            { functionCall: { name: "lookup", args: { query: "weather" } }, thoughtSignature: "tool_sig" },
+            {
+              functionCall: { id: "provider_call_1", name: "lookup", args: { query: "weather" } },
+              thoughtSignature: "tool_sig",
+            },
          ],
        },
        {
          role: "user",
-          parts: [{ functionResponse: { name: "lookup", response: { name: "lookup", content: "sunny" } } }],
+          parts: [
+            {
+              functionResponse: {
+                id: "provider_call_1",
+                name: "lookup",
+                response: { name: "lookup", content: "sunny" },
+              },
+            },
+          ],
        },
      ])
    }),
@@ -6,6 +6,8 @@ import * as path from "node:path"
 import { fileURLToPath } from "node:url"
 import { LLMClient, RequestExecutor } from "../src/route.js"
 import { ImageClient } from "../src/image-client.js"
+import { EvaluationClient } from "../src/experimental/evaluation-client.js"
+import type { Service as EvaluationClientService } from "../src/experimental/evaluation-client.js"
 import type { Service as ImageClientService } from "../src/image-client.js"
 import type { Service as LLMClientService } from "../src/route/client.js"
 import type { Service as RequestExecutorService } from "../src/route/executor.js"
@@ -18,7 +20,12 @@ import {
 const __dirname = path.dirname(fileURLToPath(import.meta.url))
 const FIXTURES_DIR = path.resolve(__dirname, "fixtures", "recordings")

-type RecordedEnv = RequestExecutorService | LLMClientService | ImageClientService | Socket.WebSocketConstructor
+type RecordedEnv =
+  | RequestExecutorService
+  | LLMClientService
+  | ImageClientService
+  | EvaluationClientService
+  | Socket.WebSocketConstructor

 type RecordedTestsOptions = RecordedGroupOptions & {
  readonly options?: HttpRecorder.RecorderOptions
@@ -92,6 +99,7 @@ export const recordedTests = (options: RecordedTestsOptions) =>
        requestExecutor,
        LLMClient.layer.pipe(Layer.provide(requestExecutor)),
        ImageClient.layer.pipe(Layer.provide(requestExecutor)),
+        EvaluationClient.layer.pipe(Layer.provide(requestExecutor)),
        webSocket,
      )
    },
@@ -19,6 +19,13 @@ export function mountBrowserPane() {
      session: "Alpha",
      mounted: true,
      visible: true,
+      url: undefined as string | undefined,
+      loading: false,
+      generation: 0,
+      delayNavigation: false,
+      pendingURL: undefined as string | undefined,
+      loadErrors: {} as Record<string, string | undefined>,
+      error: undefined as string | undefined,
      layouts: {} as Record<string, BrowserPaneLayout | undefined>,
    })
    const tabs = ["Alpha", "Beta"].map((name) => ({
@@ -47,13 +54,33 @@ export function mountBrowserPane() {
      opened: () => !!registrations.get(store.session),
      state: () => ({ tabs: tabs.filter((tab) => tab.title === store.session), focusedTabID: null }),
      tabs: () => tabs.filter((tab) => tab.title === store.session),
-      active: () => tabs.find((tab) => tab.title === store.session) ?? tabs[0],
+      active: () => {
+        const tab = tabs.find((tab) => tab.title === store.session) ?? tabs[0]
+        return {
+          ...tab,
+          url: store.url ?? tab.url,
+          loading: store.loading,
+          generation: store.generation,
+          loadError: store.loadErrors[store.session],
+        }
+      },
      registration: () => registrations.get(store.session),
-      error: () => undefined,
+      error: () => store.error ?? (store.loadErrors[store.session] ? "Request failed" : undefined),
      suspended: () => false,
      close: () => undefined,
      open: () => undefined,
-      command: () => undefined,
+      command: (command) => {
+        setStore("error", undefined)
+        if (command.type === "navigate" || command.type === "reload") setStore("loadErrors", store.session, undefined)
+        if (command.type === "navigate") {
+          if (store.delayNavigation) {
+            setStore("pendingURL", command.url)
+            return
+          }
+          setStore({ url: command.url, loading: false, generation: store.generation + 1 })
+        }
+        if (command.type === "stop") setStore("loading", false)
+      },
    }
    return (
      <>
@@ -64,6 +91,32 @@ export function mountBrowserPane() {
            {(name) => <button onClick={() => setStore({ session: name, mounted: name !== "Empty" })}>{name}</button>}
          </For>
          <button onClick={() => setStore("mounted", false)}>Unmount pane</button>
+          <button onClick={() => setStore({ url: "about:blank", loading: false })}>Blank page</button>
+          <button onClick={() => setStore({ url: "about:blank", loading: true })}>Loading page</button>
+          <button
+            onClick={() =>
+              setStore({ loading: true, generation: store.generation + 1, loadErrors: { [store.session]: undefined } })
+            }
+          >
+            Load current page
+          </button>
+          <button onClick={() => setStore("loadErrors", store.session, "ERR_CONNECTION_REFUSED")}>Failed page</button>
+          <button onClick={() => setStore("delayNavigation", true)}>Delay navigation</button>
+          <button onClick={() => setStore({ error: "ERR_BLOCKED_BY_CLIENT", pendingURL: undefined })}>
+            Block navigation
+          </button>
+          <button
+            onClick={() =>
+              setStore({
+                url: store.pendingURL,
+                pendingURL: undefined,
+                loading: false,
+                generation: store.generation + 1,
+              })
+            }
+          >
+            Complete navigation
+          </button>
          <button onClick={() => setStore("visible", (visible) => !visible)}>Toggle Review tab</button>
        </nav>
        <div style={{ width: "640px", height: "360px", border: "1px solid #555" }}>
@@ -57,3 +57,153 @@ story("hides the native view immediately while the pane stays mounted", async ({
  await toggle.click()
  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "true")
 })
+
+story("shows the empty state over a blank native page and restores navigation", async ({ page }) => {
+  const root = page.getByTestId("browser-pane-fixture")
+  await root.getByRole("button", { name: "Blank page", exact: true }).click()
+  await expect(root.getByText("Enter URL", { exact: true })).toBeVisible()
+  await expect(root.getByText('Or prompt "Open in the app browser"', { exact: true })).toBeVisible()
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "false")
+  await expect(root.getByRole("button", { name: "Reload", exact: true })).toBeDisabled()
+
+  const address = root.getByRole("textbox", { name: "Browser address", exact: true })
+  await address.fill("https://example.com/")
+  await expect(root.getByText("Enter URL", { exact: true })).toBeVisible()
+  await address.press("Enter")
+  await expect(address).not.toBeFocused()
+  await expect(root.getByText("Enter URL", { exact: true })).toBeHidden()
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "true")
+  await expect(root.getByRole("button", { name: "Reload", exact: true })).toBeEnabled()
+})
+
+story("keeps Stop available and hides the empty state while a blank page loads", async ({ page }) => {
+  const root = page.getByTestId("browser-pane-fixture")
+  await root.getByRole("button", { name: "Loading page", exact: true }).click()
+  await expect(root.getByText("Enter URL", { exact: true })).toBeHidden()
+  await root.getByRole("button", { name: "Stop", exact: true }).click()
+  await expect(root.getByText("Enter URL", { exact: true })).toBeVisible()
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "false")
+})
+
+story("keeps the submitted URL visible until the browser reports navigation", async ({ page }) => {
+  const root = page.getByTestId("browser-pane-fixture")
+  await root.getByRole("button", { name: "Blank page", exact: true }).click()
+  await root.getByRole("button", { name: "Delay navigation", exact: true }).click()
+  const address = root.getByRole("textbox", { name: "Browser address", exact: true })
+  await address.fill("https://example.com/")
+  await address.press("Enter")
+  await expect(address).not.toBeFocused()
+  await expect(address).toHaveValue("https://example.com/")
+  await expect(root.getByText("Enter URL", { exact: true })).toBeHidden()
+
+  await root.getByRole("button", { name: "Complete navigation", exact: true }).click()
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "true")
+  await expect(address).toHaveValue("https://example.com/")
+
+  await address.fill("https://unsubmitted.example/")
+  await root.getByRole("button", { name: "Delay navigation", exact: true }).click()
+  await expect(address).toHaveValue("https://example.com/")
+})
+
+story("restores the current URL when a submitted navigation is blocked", async ({ page }) => {
+  const root = page.getByTestId("browser-pane-fixture")
+  await root.getByRole("button", { name: "Delay navigation", exact: true }).click()
+  const address = root.getByRole("textbox", { name: "Browser address", exact: true })
+  await address.fill("https://blocked.example/")
+  await address.press("Enter")
+  await expect(address).toHaveValue("https://blocked.example/")
+  await root.getByRole("button", { name: "Block navigation", exact: true }).click()
+  await expect(root.getByText("ERR_BLOCKED_BY_CLIENT", { exact: true })).toBeVisible()
+  await expect(address).toHaveValue("https://alpha.example/")
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "true")
+})
+
+story("shows a themed failure state for only the failed tab and allows retry", async ({ page }) => {
+  const root = page.getByTestId("browser-pane-fixture")
+  await root.getByRole("button", { name: "Failed page", exact: true }).click()
+  await expect(root.getByText("URL can't be reached", { exact: true })).toBeVisible()
+  await expect(root.getByText("Check the URL and your connection, then try again.", { exact: true })).toBeVisible()
+  await expect(root.getByText("Request failed", { exact: true })).toBeHidden()
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "false")
+  await expect(root.getByRole("textbox", { name: "Browser address", exact: true })).toHaveValue(
+    "https://alpha.example/",
+  )
+
+  await root.getByRole("button", { name: "Beta", exact: true }).click()
+  await expect(root.getByText("URL can't be reached", { exact: true })).toBeHidden()
+  await expect(root.getByTestId("native-Beta")).toHaveAttribute("data-visible", "true")
+  await root.getByRole("button", { name: "Alpha", exact: true }).click()
+  await expect(root.getByText("URL can't be reached", { exact: true })).toBeVisible()
+
+  await root.getByRole("button", { name: "Reload", exact: true }).click()
+  await expect(root.getByText("URL can't be reached", { exact: true })).toBeHidden()
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "true")
+})
+
+story("returns a failed tab to the empty state when an empty URL is submitted", async ({ page }) => {
+  const root = page.getByTestId("browser-pane-fixture")
+  await root.getByRole("button", { name: "Failed page", exact: true }).click()
+  await expect(root.getByText("URL can't be reached", { exact: true })).toBeVisible()
+  await root.getByRole("button", { name: "Delay navigation", exact: true }).click()
+
+  const address = root.getByRole("textbox", { name: "Browser address", exact: true })
+  await address.fill("")
+  await address.press("Enter")
+  await expect(address).not.toBeFocused()
+  await expect(address).toHaveValue("")
+  await root.getByRole("button", { name: "Load current page", exact: true }).click()
+  await expect(root.getByRole("button", { name: "Stop", exact: true })).toBeEnabled()
+  await root.getByRole("button", { name: "Complete navigation", exact: true }).click()
+  await expect(root.getByText("URL can't be reached", { exact: true })).toBeHidden()
+  await expect(root.getByText("Enter URL", { exact: true })).toBeVisible()
+  await expect(root.getByRole("button", { name: "Reload", exact: true })).toBeDisabled()
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "false")
+})
+
+story("selects the full URL when the address field gains focus", async ({ page }) => {
+  const root = page.getByTestId("browser-pane-fixture")
+  const address = root.getByRole("textbox", { name: "Browser address", exact: true })
+  await address.click()
+  await expect(address).toHaveJSProperty("selectionStart", 0)
+  await expect(address).toHaveJSProperty("selectionEnd", "https://alpha.example/".length)
+  await address.pressSequentially("https://example.com/")
+  await expect(address).toHaveValue("https://example.com/")
+  await address.press("Enter")
+  await expect(address).not.toBeFocused()
+  await address.focus()
+  await expect(address).toHaveJSProperty("selectionStart", 0)
+  await expect(address).toHaveJSProperty("selectionEnd", "https://example.com/".length)
+  await address.press("ArrowRight")
+  await address.click()
+  await expect(address).toHaveJSProperty("selectionStart", 0)
+  await expect(address).toHaveJSProperty("selectionEnd", "https://example.com/".length)
+})
+
+story("keeps the current page visible while a submitted URL loads", async ({ page }) => {
+  const root = page.getByTestId("browser-pane-fixture")
+  await root.getByRole("button", { name: "Delay navigation", exact: true }).click()
+  const address = root.getByRole("textbox", { name: "Browser address", exact: true })
+  await address.fill("https://example.com/")
+  await address.press("Enter")
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "true")
+  await expect(address).toHaveValue("https://example.com/")
+
+  await root.getByRole("button", { name: "Load current page", exact: true }).click()
+  await expect(root.getByRole("button", { name: "Stop", exact: true })).toBeEnabled()
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "true")
+  await root.getByRole("button", { name: "Complete navigation", exact: true }).click()
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "true")
+  await expect(address).toHaveValue("https://example.com/")
+})
+
+story("keeps the current page and restores its URL when an empty address is submitted", async ({ page }) => {
+  const root = page.getByTestId("browser-pane-fixture")
+  const address = root.getByRole("textbox", { name: "Browser address", exact: true })
+  await address.fill("")
+  await address.press("Enter")
+  await expect(address).not.toBeFocused()
+  await expect(address).toHaveValue("https://alpha.example/")
+  await expect(root.getByTestId("native-Alpha")).toHaveAttribute("data-visible", "true")
+  await expect(root.getByText("Enter URL", { exact: true })).toBeHidden()
+  await expect(root.getByRole("button", { name: "Reload", exact: true })).toBeEnabled()
+})
@@ -17,14 +17,12 @@ const milestones = [
  "electronSpawnStarted",
  "debugEndpointReady",
  "electronStarted",
+  "layersReady",
+  "windowVisible",
  "serviceEnsureStarted",
  "serviceSpawnRequested",
  "serviceReady",
-  "backgroundLoadingReady",
  "rendererViteConnected",
-  "rendererInitializationStarted",
-  "rendererInitializationReady",
-  "windowVisible",
  "homeReady",
 ] as const
 const phases = [
@@ -128,14 +126,12 @@ const milestonePatterns: ReadonlyArray<{ name: Milestone; text: string }> = [
  { name: "electronSpawnStarted", text: "starting electron app..." },
  { name: "debugEndpointReady", text: "DevTools listening on ws://" },
  { name: "electronStarted", text: "app starting" },
+  { name: "layersReady", text: "layers ready" },
+  { name: "windowVisible", text: "main window visible" },
  { name: "serviceEnsureStarted", text: "starting v2 background service" },
  { name: "serviceSpawnRequested", text: "v2 CLI background service starting" },
  { name: "serviceReady", text: "v2 CLI background service ready" },
-  { name: "backgroundLoadingReady", text: "loading task finished" },
  { name: "rendererViteConnected", text: "[vite] connected." },
-  { name: "rendererInitializationStarted", text: "awaiting server ready" },
-  { name: "rendererInitializationReady", text: "server ready" },
-  { name: "windowVisible", text: "main window visible" },
 ]

 async function createColdProfile() {
@@ -404,14 +400,12 @@ function requireMilestones(observed: Partial<Record<Milestone, number>>) {
    electronSpawnStarted: get("electronSpawnStarted"),
    debugEndpointReady: get("debugEndpointReady"),
    electronStarted: get("electronStarted"),
+    layersReady: get("layersReady"),
+    windowVisible: get("windowVisible"),
    serviceEnsureStarted: get("serviceEnsureStarted"),
    serviceSpawnRequested: get("serviceSpawnRequested"),
    serviceReady: get("serviceReady"),
-    backgroundLoadingReady: get("backgroundLoadingReady"),
    rendererViteConnected: get("rendererViteConnected"),
-    rendererInitializationStarted: get("rendererInitializationStarted"),
-    rendererInitializationReady: get("rendererInitializationReady"),
-    windowVisible: get("windowVisible"),
    homeReady: get("homeReady"),
  }
 }
@@ -703,7 +703,7 @@ function messageContent(
    return {
      type: "reasoning",
      text: part.text,
-      state: jsonRecord(part.metadata),
+      native: jsonRecord(part.metadata),
      time: part.time
        ? { created: part.time.start, ...(part.time.end === undefined ? {} : { completed: part.time.end }) }
        : undefined,
@@ -20,14 +20,12 @@ describe("desktop startup benchmark", () => {
      ["electronSpawnStarted", "starting electron app..."],
      ["debugEndpointReady", "DevTools listening on ws://"],
      ["electronStarted", "app starting"],
+      ["layersReady", "layers ready"],
+      ["windowVisible", "main window visible"],
      ["serviceEnsureStarted", "starting v2 background service"],
      ["serviceSpawnRequested", "v2 CLI background service starting"],
      ["serviceReady", "v2 CLI background service ready"],
-      ["backgroundLoadingReady", "loading task finished"],
      ["rendererViteConnected", "[vite] connected."],
-      ["rendererInitializationStarted", "awaiting server ready"],
-      ["rendererInitializationReady", "server ready"],
-      ["windowVisible", "main window visible"],
    ] as const
    cases.forEach(([milestone, line]) => {
      expect(milestoneForLine(`\u001b[32m${line}\u001b[39m`)).toBe(milestone)
@@ -58,14 +56,12 @@ function sample(run: number, commandToHomeReadyMs: number): DesktopStartupSample
    electronSpawnStarted: 7,
    debugEndpointReady: 8,
    electronStarted: 9,
-    serviceEnsureStarted: 10,
-    serviceSpawnRequested: 11,
-    serviceReady: 12,
-    backgroundLoadingReady: 13,
-    rendererViteConnected: 14,
-    rendererInitializationStarted: 15,
-    rendererInitializationReady: 16,
-    windowVisible: 17,
+    layersReady: 10,
+    windowVisible: 11,
+    serviceEnsureStarted: 12,
+    serviceSpawnRequested: 13,
+    serviceReady: 14,
+    rendererViteConnected: 15,
    homeReady: commandToHomeReadyMs,
  }
  return {
@@ -80,8 +76,8 @@ function sample(run: number, commandToHomeReadyMs: number): DesktopStartupSample
      electronStartup: 2,
      serviceSpawnWait: 1,
      serviceProcessStartup: 1,
-      rendererStartup: commandToHomeReadyMs - 14,
-      visibleWindowToHome: commandToHomeReadyMs - 17,
+      rendererStartup: commandToHomeReadyMs - 15,
+      visibleWindowToHome: commandToHomeReadyMs - 11,
    },
    service: { version: "2.0.0-local-test", url: "http://127.0.0.1:3000", pid: run },
  }
@@ -71,7 +71,7 @@ for (const direction of ["ltr", "rtl"] as const) {
    const shifted = await content.evaluate((element) => getComputedStyle(element).translate)
    await content.evaluate((element) => element.setAttribute("data-summary-motion", ""))
    // Keep issuing resize events before the idle timer expires, including crossing the width cutoff.
-    for (const width of [1520, 1280, 1600]) {
+    for (const width of [1520, 1280, 1800]) {
      await page.setViewportSize({ width, height: 900 })
      await expect(panel).toHaveAttribute("data-summary-resizing", "true")
      await page.clock.runFor(100)
@@ -84,6 +84,7 @@ for (const direction of ["ltr", "rtl"] as const) {
    await expect(content).toHaveAttribute("data-summary-motion", "transitionrun,transitionend,")
    await expect(content).not.toHaveCSS("translate", shifted)
    await page.setViewportSize({ width: 1440, height: 900 })
+    await expect(panel).toHaveAttribute("data-summary-resizing", "false")
    await expect(content).toHaveCSS("translate", shifted)

    await content.evaluate((element) => element.setAttribute("data-summary-motion", ""))
@@ -112,7 +113,8 @@ for (const direction of ["ltr", "rtl"] as const) {
    await expect(summary).toBeVisible()

    await page.setViewportSize({ width: 1800, height: 900 })
-    await expect(content).toHaveCSS("translate", "0px")
+    await expect(panel).toHaveAttribute("data-summary-resizing", "false")
+    await expect(content).toHaveCSS("translate", "none")
    await expect(summary).toBeVisible()

    await page.emulateMedia({ reducedMotion: "reduce" })
@@ -116,7 +116,7 @@ test("single-server settings expose scoped pages without a server picker", async
  await expect(connection.getByRole("heading", { name: "Connection", exact: true })).toBeVisible()
  await expect(connection.locator('[data-component="settings-list"]')).toHaveCSS("padding-left", "16px")
  await expect(connection.locator(".settings-servers-row")).toHaveCSS("padding-top", "20px")
-  await expect(connection.locator(".settings-servers-lead")).toHaveCSS("column-gap", "4px")
+  await expect(connection.locator(".settings-servers-lead")).toHaveCSS("column-gap", "10px")
  await expect(connection.locator(".settings-servers-copy")).toHaveCSS("row-gap", "6px")
  await expect(settings.getByRole("heading", { name: "Preferences", exact: true })).toBeVisible()
  await expect(settings.getByText("Terminal shell", { exact: true })).toBeVisible()
@@ -1,6 +1,6 @@
 {
  "name": "@opencode/app",
-  "version": "2.0.10",
+  "version": "2.0.12",
  "description": "",
  "type": "module",
  "exports": {
@@ -65,14 +65,14 @@
  }

  /* Keep the 1000px conversation intact, with 320px for the summary and its gutters.
-     Move only as far as needed; wider panels already have enough space in the margin. */
-  @container session-chat (min-width: 1320px) {
+     When they overlap, center the conversation in the space that remains beside the summary. */
+  @container session-chat (min-width: 1320px) and (width < 1640px) {
    [data-slot="session-chat-panel"][data-summary-open="true"]
      :is([data-timeline-virtual-content], [data-component="session-composer-dock"] > div) {
-      --session-summary-translate: min(0px, calc(50cqi - 820px));
+      --session-summary-translate: -160px;

      &:dir(rtl) {
-        --session-summary-translate: max(0px, calc(820px - 50cqi));
+        --session-summary-translate: 160px;
      }
    }
  }
@@ -625,6 +625,16 @@ export const dict = {
  "toast.file.loadFailed.title": "Failed to load file",
  "file.error.notFound": "File not found: {{name}}",
  "toast.file.listFailed.title": "Failed to list files",
+  "file.view.preview": "Preview",
+  "file.view.source": "Source",
+  "file.view.openInBrowser": "Open in browser",
+  "file.view.binary": "Binary file · {{size}}",
+  "file.view.table.rows.one": "{{count}} row",
+  "file.view.table.rows.other": "{{count}} rows",
+  "file.view.table.columns.one": "{{count}} column",
+  "file.view.table.columns.other": "{{count}} columns",
+  "file.view.table.truncated": "Showing the first {{shown}} of {{total}} rows.",
+  "file.view.fontSample": "Sphinx of black quartz, judge my vow.",

  "toast.context.noLineSelection.title": "No line selection",
  "toast.context.noLineSelection.description": "Select a line range in a file tab first.",
@@ -906,6 +916,10 @@ export const dict = {
  "session.browser.replaced": "Browser control moved to another desktop window.",
  "session.browser.suspended": "Browser suspended. Interact with this session to reconnect.",
  "session.browser.address.placeholder": "Enter URL",
+  "session.browser.empty.title": "Enter URL",
+  "session.browser.empty.description": 'Or prompt "Open in the app browser"',
+  "session.browser.failed.title": "URL can't be reached",
+  "session.browser.failed.description": "Check the URL and your connection, then try again.",

  "titlebar.update": "Update",
  "titlebar.tabs": "Tabs",
@@ -19,6 +19,7 @@ export type BrowserPaneCommand = Browser.Action
 export type BrowserPaneState = Browser.State | null
 export type BrowserPaneEvent =
  | { type: "focus"; tabID: Browser.TabID }
+  | { type: "preview"; path: string }
  | { type: "state"; state: BrowserPaneState; error?: string }

 export type BrowserPaneRegistration = {
@@ -33,6 +33,8 @@ export type FileContent = {
  }
  encoding?: "base64"
  mimeType?: string
+  /** On-disk size when the bytes themselves are not retained. */
+  size?: number
 }

 export type Path = {
@@ -1,14 +1,15 @@
-import { createEffect, createMemo, getOwner, on, onCleanup, runWithOwner } from "solid-js"
+import { batch, createEffect, createMemo, createRoot, getOwner, on, onCleanup, runWithOwner } from "solid-js"
 import { createStore, reconcile } from "solid-js/store"
 import { createSimpleContext } from "@opencode/ui/context"
-import type { Browser } from "@opencode/plugin-browser/rpc"
 import { useLanguage } from "@/runtime/i18n/language"
 import type { BrowserPaneCommand } from "@/runtime/platform/browser-pane"
 import { usePlatform } from "@/runtime/platform/platform"
 import type { useServer } from "@/runtime/server/current"
+import type { SessionStateKey } from "@/runtime/server/scope"
 import { useSettings } from "@/settings/model"
 import { findSessionTab, tabKey, useTabs } from "@/shell/tabs/tabs"
-import { useCurrentRoute } from "@/shell/state/layout"
+import { useCurrentRoute, useLayout } from "@/shell/state/layout"
+import { sessionBrowserTab } from "@/shell/state/session-tabs"
 import { createEventListener } from "@solid-primitives/event-listener"
 import { createBrowserConnection, type BrowserConnectionState } from "./connection"

@@ -35,13 +36,14 @@ export const { use: useBrowserAttachments, provider: BrowserAttachmentsProvider
    const settings = useSettings()
    const language = useLanguage()
    const shellTabs = useTabs()
+    const layout = useLayout()
    const route = useCurrentRoute()
    const owner = getOwner()
    const [store, setStore] = createStore<Record<string, BrowserAttachment | undefined>>({})
    // Servers whose plugin lacks the browser RPC; sessions on them stop retrying.
    const [unsupported, setUnsupported] = createStore<Record<string, true | undefined>>({})
    const live = new Map<string, Live>()
-    const focus = new Map<string, Set<(tabID: Browser.TabID) => void>>()
+    const preview = new Map<string, Set<(path: string) => void>>()
    const key = (server: Server, sessionID: string) => `${server.key}\n${sessionID}`
    const enabled = createMemo(
      () => !!platform.browserPane && settings.ready() && settings.general.experimentalBrowser(),
@@ -87,11 +89,14 @@ export const { use: useBrowserAttachments, provider: BrowserAttachmentsProvider
      enabled,
      supported: (server: Server) => !unsupported[server.key],
      state: (server: Server, sessionID: string) => store[key(server, sessionID)],
-      attach(server: Server, sessionID: string) {
+      attach(server: Server, sessionID: string, sessionKey: SessionStateKey) {
        const id = key(server, sessionID)
        if (live.has(id)) return
        const pane = platform.browserPane
        if (!pane || !enabled() || unsupported[server.key] || server.health?.incompatible) return
+        // Focus requests write to the owning session's layout even while another shell tab is routed,
+        // so the Review pane and browser tab are already selected when the user returns to it.
+        const tabs = createRoot((dispose) => ({ dispose, layout: layout.tabs(sessionKey) }), owner)
        const connection = createBrowserConnection({
          pane,
          // Resolve the current port at every wake, including after sidecar replacement.
@@ -100,7 +105,15 @@ export const { use: useBrowserAttachments, provider: BrowserAttachmentsProvider
            sessionID,
            endpoint: { ...server.conn.http, url: server.ctx.sdk.url },
          }),
-          focus: (tabID) => focus.get(id)?.forEach((listener) => listener(tabID)),
+          focus: (tabID) => {
+            const tab = sessionBrowserTab(tabID)
+            batch(() => {
+              shellTabs.setPane(findSessionTab(shellTabs.store, server.key, sessionID), "review", true)
+              if (!tabs.layout.all().includes(tab)) tabs.layout.setAll([...tabs.layout.all(), tab])
+              tabs.layout.setActive(tab)
+            })
+          },
+          preview: (path) => preview.get(id)?.forEach((listener) => listener(path)),
          change: (state) => {
            if (state.error === "browser.pane.unsupported") {
              setUnsupported(server.key, true)
@@ -138,17 +151,18 @@ export const { use: useBrowserAttachments, provider: BrowserAttachmentsProvider
        entry.dispose = () => {
          unsubscribe?.forEach((dispose) => dispose())
          connection.dispose()
+          tabs.dispose()
        }
      },
-      /** Desktop focus requests for a mounted session route; nothing is replayed to routes mounted later. */
-      onFocus(server: Server, sessionID: string, listener: (tabID: Browser.TabID) => void) {
+      /** Agent requests to show a file in this session's Review pane. */
+      onPreview(server: Server, sessionID: string, listener: (path: string) => void) {
        const id = key(server, sessionID)
-        const listeners = focus.get(id) ?? new Set()
+        const listeners = preview.get(id) ?? new Set()
        listeners.add(listener)
-        focus.set(id, listeners)
+        preview.set(id, listeners)
        return () => {
          listeners.delete(listener)
-          if (!listeners.size) focus.delete(id)
+          if (!listeners.size) preview.delete(id)
        }
      },
      command(server: Server, sessionID: string, command: BrowserPaneCommand) {
@@ -28,10 +28,12 @@ function fixture() {
    commands: Browser.Action[]
  }[] = []
  const endpoint = { url: "http://localhost:4096" }
+  const previews: string[] = []
  const connection = createBrowserConnection({
    target: () => ({ serverKey: "browser-test", sessionID: "ses_browser", endpoint: { ...endpoint } }),
    change: (state) => states.push(state),
    focus: () => {},
+    preview: (path) => previews.push(path),
    pane: {
      register(target, emit) {
        const call = { target, emit, closed: false, commands: [] as Browser.Action[] }
@@ -50,9 +52,21 @@ function fixture() {
  })
  connection.wake()
  calls[0].emit({ type: "state", state: browser })
-  return { connection, calls, states, endpoint }
+  return { connection, calls, states, endpoint, previews }
 }

+test("preview requests reach the session without touching connection state", () => {
+  const app = fixture()
+  try {
+    const before = app.states.length
+    app.calls[0].emit({ type: "preview", path: "docs/report.pdf" })
+    expect(app.previews).toEqual(["docs/report.pdf"])
+    expect(app.states).toHaveLength(before)
+  } finally {
+    app.connection.dispose()
+  }
+})
+
 test("suspension retains tabs and reconnects once on demand using the current endpoint", async () => {
  const app = fixture()
  try {
@@ -19,6 +19,7 @@ export function createBrowserConnection(input: {
  target: () => BrowserPaneTarget
  change: (state: BrowserConnectionState) => void
  focus: (tabID: Browser.TabID) => void
+  preview: (path: string) => void
 }) {
  const state: BrowserConnectionState = { browser: null, suspended: false }
  let disposed = false
@@ -33,6 +34,7 @@ export function createBrowserConnection(input: {
      (event) => {
        if (disposed || state.registration !== registration) return
        if (event.type === "focus") return input.focus(event.tabID)
+        if (event.type === "preview") return input.preview(event.path)
        if (event.error === "browser.pane.unsupported" || event.error === "browser.pane.replaced") {
          blocked = true
          registration.close()
@@ -1,4 +1,4 @@
-import { batch, createEffect, createMemo, on, onCleanup } from "solid-js"
+import { batch, createEffect, createMemo, on } from "solid-js"
 import type { Browser } from "@opencode/plugin-browser/rpc"
 import { createStore } from "solid-js/store"
 import { useLanguage } from "@/runtime/i18n/language"
@@ -33,13 +33,6 @@ export function createSessionBrowser(session: SessionModel) {
      attachment()?.browser?.tabs.filter((tab) => session.layout.tabs().all().includes(sessionBrowserTab(tab.id))) ??
      [],
  )
-  const focus = (tabID: Browser.TabID) => {
-    session.layout.view().reviewPanel.open()
-    const tabs = session.layout.tabs()
-    const key = sessionBrowserTab(tabID)
-    if (!tabs.all().includes(key)) tabs.setAll([...tabs.all(), key])
-    tabs.setActive(key)
-  }
  const command = (command: BrowserPaneCommand) => {
    const sessionID = session.identity.sessionID()
    if (!sessionID) return
@@ -66,8 +59,7 @@ export function createSessionBrowser(session: SessionModel) {
  createEffect(() => {
    const sessionID = session.identity.sessionID()
    if (!sessionID) return
-    if (attachments.enabled()) attachments.attach(server, sessionID)
-    onCleanup(attachments.onFocus(server, sessionID, focus))
+    if (attachments.enabled()) attachments.attach(server, sessionID, session.layout.sessionKey())
  })
  createEffect(
    on(
@@ -20,13 +20,18 @@ export function SessionBrowserPane(props: { browser: ReturnType<typeof createSes
  const command = useCommand()
  const state = props.browser.active
  const address = () => (state()?.url === "about:blank" ? "" : (state()?.url ?? ""))
+  const failed = () => !!state()?.loadError
  const registration = props.browser.registration
  const button = { variant: "ghost", size: "large" } as const
  const [store, setStore] = createStore({
    address: "",
    editing: false,
+    submitted: false,
+    // A submitted navigation the browser has not reported yet; keeps the empty state hidden meanwhile.
+    navigating: false,
    visible: typeof document === "undefined" || document.visibilityState === "visible",
  })
+  const empty = () => !address() && !state()?.loading && !store.navigating
  let surface: HTMLDivElement | undefined
  let addressDisplay: HTMLDivElement | undefined
  let frame: number | undefined
@@ -43,7 +48,7 @@ export function SessionBrowserPane(props: { browser: ReturnType<typeof createSes
      title: language.t("command.browser.reload"),
      category: language.t("command.category.view"),
      keybind: "f5",
-      disabled: !props.visible || !state(),
+      disabled: !props.visible || !address(),
      onSelect: () => {
        const tab = state()
        if (tab) props.browser.command({ type: "reload", tabID: tab.id })
@@ -71,7 +76,9 @@ export function SessionBrowserPane(props: { browser: ReturnType<typeof createSes
    const top = Math.round(rect.top * zoom)
    const right = Math.round(rect.right * zoom)
    const bottom = Math.round(rect.bottom * zoom)
-    const visible = props.visible && store.visible && !dialog.active && !covered(rect)
+    // The desktop page hides blank and loading documents itself; only hide here
+    // while the pane shows its own empty or failed state over the surface.
+    const visible = props.visible && store.visible && !empty() && !failed() && !dialog.active && !covered(rect)
    // The cutout exposes the app backdrop outside the rounded Review card,
    // not the browser surface inside it.
    const color = getComputedStyle(
@@ -107,7 +114,25 @@ export function SessionBrowserPane(props: { browser: ReturnType<typeof createSes
    if (frame === undefined) frame = requestAnimationFrame(tick)
  }

-  createEffect(() => !store.editing && setStore("address", address()))
+  createEffect(on([() => state()?.id, address], () => !store.editing && setStore("address", address())))
+  // Any reported movement, including a rejected or blocked request, ends the submitted navigation.
+  createEffect(
+    on(
+      [() => state()?.id, () => state()?.generation, () => state()?.loading, () => props.browser.error()],
+      () => setStore("navigating", false),
+      { defer: true },
+    ),
+  )
+  // A blocked or rejected submission leaves the page where it was; show that page's URL again.
+  createEffect(
+    on(
+      () => props.browser.error(),
+      (error) => {
+        if (error && !store.editing) setStore("address", address())
+      },
+      { defer: true },
+    ),
+  )
  createEffect(
    on(registration, (current) => {
      // Session routes can change before this pane unmounts. Hide the registration
@@ -123,6 +148,8 @@ export function SessionBrowserPane(props: { browser: ReturnType<typeof createSes
        () => store.visible,
        () => props.visible,
        () => state()?.id,
+        empty,
+        failed,
        registration,
      ],
      () => {
@@ -157,7 +184,7 @@ export function SessionBrowserPane(props: { browser: ReturnType<typeof createSes

  return (
    <aside id="browser-panel" class="relative size-full min-w-0 overflow-hidden bg-v2-background-bg-base flex flex-col">
-      <div class="h-10 shrink-0 flex items-center gap-1 px-2 border-b border-v2-border-border-muted">
+      <div class="h-10 shrink-0 flex items-center gap-1 px-3 border-b border-v2-border-border-muted">
        <For each={["back", "forward"] as const}>
          {(direction) => (
            <Tooltip placement="top" value={language.t(direction === "back" ? "common.goBack" : "common.goForward")}>
@@ -193,7 +220,7 @@ export function SessionBrowserPane(props: { browser: ReturnType<typeof createSes
        >
          <IconButton
            {...button}
-            disabled={!state()}
+            disabled={!state()?.loading && !address()}
            aria-label={language.t(state()?.loading ? "prompt.action.stop" : "error.page.action.reload")}
            onClick={() => {
              const tab = state()
@@ -212,8 +239,13 @@ export function SessionBrowserPane(props: { browser: ReturnType<typeof createSes
          onSubmit={(event) => {
            event.preventDefault()
            const tab = state()
-            if (tab && store.address.trim())
-              props.browser.command({ type: "navigate", tabID: tab.id, url: store.address })
+            const url = store.address.trim()
+            if (!tab) return
+            if (url || failed()) {
+              setStore({ submitted: true, address: url, navigating: true })
+              props.browser.command({ type: "navigate", tabID: tab.id, url: url || "about:blank" })
+            }
+            event.currentTarget.querySelector("input")?.blur()
          }}
        >
          <input
@@ -224,8 +256,14 @@ export function SessionBrowserPane(props: { browser: ReturnType<typeof createSes
            disabled={!state()}
            placeholder={language.t("session.browser.address.placeholder")}
            aria-label={language.t("session.browser.address")}
-            onFocus={() => setStore("editing", true)}
-            onBlur={() => setStore({ editing: false, address: address() })}
+            onFocus={(event) => {
+              setStore("editing", true)
+              event.currentTarget.select()
+            }}
+            onClick={(event) => event.currentTarget.select()}
+            onBlur={() =>
+              setStore({ editing: false, address: store.submitted ? store.address : address(), submitted: false })
+            }
            onInput={(event) => setStore("address", event.currentTarget.value)}
            onScroll={(event) => {
              if (addressDisplay) addressDisplay.scrollLeft = event.currentTarget.scrollLeft
@@ -243,12 +281,27 @@ export function SessionBrowserPane(props: { browser: ReturnType<typeof createSes
          </div>
        </form>
      </div>
-      <Show when={props.browser.error()}>
+      <Show when={props.browser.error() && !failed()}>
        <div class="shrink-0 px-3 py-1.5 text-12-regular text-text-danger-base border-b border-v2-border-border-muted">
          {props.browser.error()}
        </div>
      </Show>
      <div ref={surface} class="min-h-0 flex-1 bg-v2-background-bg-base flex items-center justify-center">
+        <Show when={(empty() || failed()) && !props.browser.suspended()}>
+          {/* Add the 40px toolbar to the file empty state's 160px bottom padding to align their centers. */}
+          <div
+            dir="auto"
+            class="flex size-full flex-col items-center justify-center gap-2 p-6 pb-[200px] text-center text-text-weak"
+          >
+            <Icon name="globe" size="large" class="mb-2 shrink-0" />
+            <div class="text-[13px] font-medium leading-[var(--line-height-compact)] text-text-strong">
+              {language.t(failed() ? "session.browser.failed.title" : "session.browser.empty.title")}
+            </div>
+            <div class="text-13-regular leading-[var(--line-height-base)]">
+              {language.t(failed() ? "session.browser.failed.description" : "session.browser.empty.description")}
+            </div>
+          </div>
+        </Show>
        <Show when={props.browser.suspended()}>
          <p class="px-6 text-center text-13-regular text-v2-text-text-subtle" role="status">
            {language.t("session.browser.suspended")}
@@ -0,0 +1,94 @@
+/* The control defaults to a fixed 232px with equal segments; here it hugs its two labels. */
+[data-slot="artifact-toolbar"] [data-slot="segmented-control-v2"] {
+  width: auto;
+}
+
+[data-slot="artifact-toolbar"] [data-slot="segmented-control-v2-item"] {
+  flex: 0 0 auto;
+  padding: 0 14px;
+}
+
+/* Shrink-wrapped segments round the label box down a fraction; the ellipsis overflow then clips glyph edges. */
+[data-slot="artifact-toolbar"] [data-slot="segmented-control-v2-item-label"] {
+  overflow: visible;
+  max-width: none;
+}
+
+[data-slot="artifact-stage"] {
+  --artifact-check: color-mix(in oklch, var(--v2-text-text-base) 5%, transparent);
+  background-color: var(--v2-background-bg-deep);
+}
+
+[data-slot="artifact-stage"][data-checker] {
+  background-image:
+    linear-gradient(45deg, var(--artifact-check) 25%, transparent 25%),
+    linear-gradient(-45deg, var(--artifact-check) 25%, transparent 25%),
+    linear-gradient(45deg, transparent 75%, var(--artifact-check) 75%),
+    linear-gradient(-45deg, transparent 75%, var(--artifact-check) 75%);
+  background-size: 16px 16px;
+  background-position:
+    0 0,
+    0 8px,
+    8px -8px,
+    -8px 0;
+}
+
+[data-slot="artifact-media"] {
+  display: block;
+  border-radius: 4px;
+  box-shadow:
+    0 0 0 0.5px var(--v2-border-border-base),
+    0 12px 32px -12px color-mix(in oklch, var(--v2-text-text-base) 25%, transparent);
+}
+
+[data-slot="artifact-stage"][data-zoom="fit"] [data-slot="artifact-media"] {
+  max-width: 100%;
+  max-height: 100%;
+  object-fit: contain;
+}
+
+[data-slot="artifact-stage"][data-zoom="fit"][data-overflow] [data-slot="artifact-media"] {
+  cursor: zoom-in;
+}
+
+[data-slot="artifact-stage"][data-zoom="actual"] [data-slot="artifact-media"] {
+  cursor: zoom-out;
+}
+
+[data-slot="artifact-table"] {
+  border-collapse: separate;
+  border-spacing: 0;
+  font-variant-numeric: tabular-nums;
+}
+
+[data-slot="artifact-table"] th,
+[data-slot="artifact-table"] td {
+  padding: 5px 12px;
+  border-bottom: 1px solid var(--v2-border-border-muted);
+  border-inline-end: 1px solid var(--v2-border-border-muted);
+  white-space: pre;
+  max-width: 40ch;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  text-align: start;
+  line-height: var(--line-height-compact);
+}
+
+[data-slot="artifact-table"] th {
+  position: sticky;
+  top: 0;
+  z-index: 1;
+  background: var(--v2-background-bg-layer-01);
+  font-weight: var(--font-weight-medium);
+  color: var(--v2-text-text-muted);
+}
+
+[data-slot="artifact-table"] tbody tr:hover td {
+  background: color-mix(in oklch, var(--v2-text-text-base) 3%, transparent);
+}
+
+[data-slot="artifact-table"] td[data-index] {
+  color: var(--v2-text-text-faint);
+  text-align: end;
+  user-select: none;
+}
@@ -0,0 +1,454 @@
+import { createEffect, createMemo, For, Match, on, onCleanup, Show, Switch, type JSX } from "solid-js"
+import { createStore } from "solid-js/store"
+import { createResizeObserver } from "@solid-primitives/resize-observer"
+import { Button } from "@opencode/ui/button"
+import { FileIcon } from "@opencode/ui/file-icon"
+import { SegmentedControl, SegmentedControlItem } from "@opencode/ui/segmented-control"
+import { ScrollView } from "@opencode/ui/scroll-view"
+import { Markdown } from "@opencode/session-ui/markdown"
+import { MarkdownProvider, useMarkdown } from "@opencode/session-ui/context/markdown"
+import { getDirectory, getFilename } from "@opencode/util/path"
+import type { FileContent } from "@/runtime/server/types"
+import { useLanguage } from "@/runtime/i18n/language"
+import {
+  artifactKind,
+  blobUrlFromContent,
+  contentBytes,
+  parseDelimited,
+  resolveArtifactPath,
+  type ArtifactKind,
+} from "@/workspaces/files/artifact"
+import { useArtifactOpener } from "@/session/files/open-artifact"
+import "./artifact-view.css"
+
+type ArtifactMode = "preview" | "source"
+
+/** Facts a viewer learns from the decoded media, shown in the toolbar. */
+type ArtifactInfo = { width?: number; height?: number; duration?: number; rows?: number; columns?: number }
+
+type MediaProps = {
+  path: string
+  content: FileContent
+  onInfo: (info: ArtifactInfo) => void
+  /** The browser could not decode the bytes; the host falls back to the binary placeholder. */
+  onError: () => void
+}
+
+/** Kinds that render a preview from their text and can toggle back to highlighted source. */
+const previewableKinds = new Set<ArtifactKind>(["svg", "html", "markdown", "mermaid", "table"])
+
+/**
+ * Renders a loaded non-text file: media, documents, and data get a dedicated viewer with a toolbar;
+ * previewable text kinds can switch to `source`, which the host supplies (its code view).
+ */
+export function ArtifactView(props: { path: string; content: FileContent; cacheKey?: string; source: JSX.Element }) {
+  const language = useLanguage()
+  const [state, setState] = createStore({
+    mode: "preview" as ArtifactMode,
+    info: {} as ArtifactInfo,
+    // Media the browser could not decode falls back to the binary placeholder.
+    undecodable: false,
+  })
+  createEffect(
+    on(
+      () => props.content,
+      () => setState({ mode: "preview", info: {}, undecodable: false }),
+      { defer: true },
+    ),
+  )
+
+  const kind = createMemo<ArtifactKind | "binary">(() => {
+    if (props.content.type === "binary" && !props.content.mimeType) return "binary"
+    if (state.undecodable) return "binary"
+    return artifactKind(props.path)
+  })
+  const previewable = createMemo(() => {
+    const value = kind()
+    return value !== "binary" && previewableKinds.has(value)
+  })
+  const meta = createMemo(() => {
+    const info = state.info
+    return [
+      info.width && info.height ? `${info.width} × ${info.height}` : undefined,
+      info.duration ? formatDuration(info.duration) : undefined,
+      info.rows !== undefined ? language.plural("file.view.table.rows", Math.max(0, info.rows - 1)) : undefined,
+      info.columns !== undefined ? language.plural("file.view.table.columns", info.columns) : undefined,
+      formatBytes(language.intl(), contentBytes(props.content)),
+    ].filter((item): item is string => !!item)
+  })
+
+  const media = { onInfo: (info: ArtifactInfo) => setState("info", info), onError: () => setState("undecodable", true) }
+  const rendered = () => (
+    <ScrollView class="min-h-0 flex-1">
+      <Show
+        when={kind() === "markdown"}
+        fallback={<ArtifactMermaid text={props.content.content} cacheKey={props.cacheKey} />}
+      >
+        <ArtifactMarkdown path={props.path} text={props.content.content} cacheKey={props.cacheKey} />
+      </Show>
+    </ScrollView>
+  )
+
+  return (
+    <>
+      <ArtifactToolbar
+        mode={state.mode}
+        onModeChange={previewable() ? (mode) => setState("mode", mode) : undefined}
+        meta={meta()}
+        actions={
+          <Show when={kind() === "html"}>
+            <OpenInBrowserButton path={props.path} />
+          </Show>
+        }
+      />
+      <Show when={!previewable() || state.mode === "preview"} fallback={props.source}>
+        <Switch>
+          <Match when={kind() === "image" || kind() === "svg"}>
+            <ArtifactImage path={props.path} content={props.content} {...media} />
+          </Match>
+          <Match when={kind() === "video"}>
+            <ArtifactVideo path={props.path} content={props.content} {...media} />
+          </Match>
+          <Match when={kind() === "audio"}>
+            <ArtifactAudio path={props.path} content={props.content} {...media} />
+          </Match>
+          <Match when={kind() === "pdf" || kind() === "html"}>
+            <ArtifactFrame path={props.path} content={props.content} kind={kind() === "pdf" ? "pdf" : "html"} />
+          </Match>
+          <Match when={kind() === "font"}>
+            <ArtifactFont path={props.path} content={props.content} />
+          </Match>
+          <Match when={kind() === "table"}>
+            <ArtifactTable path={props.path} text={props.content.content} onInfo={media.onInfo} />
+          </Match>
+          <Match when={kind() === "markdown" || kind() === "mermaid"}>{rendered()}</Match>
+          <Match when={kind() === "binary"}>
+            <ArtifactBinary path={props.path} size={formatBytes(language.intl(), contentBytes(props.content))} />
+          </Match>
+        </Switch>
+      </Show>
+    </>
+  )
+}
+
+function formatBytes(locale: string, bytes: number) {
+  const units = ["byte", "kilobyte", "megabyte", "gigabyte"] as const
+  const index = Math.min(units.length - 1, bytes > 0 ? Math.floor(Math.log10(bytes) / 3) : 0)
+  const value = bytes / 1000 ** index
+  return new Intl.NumberFormat(locale, {
+    style: "unit",
+    unit: units[index],
+    // "short" bytes render as the singular "byte"; the long form pluralizes correctly.
+    unitDisplay: index === 0 ? "long" : "short",
+    maximumFractionDigits: value >= 100 || index === 0 ? 0 : 1,
+  }).format(value)
+}
+
+function formatDuration(seconds: number) {
+  const total = Math.round(seconds)
+  const minutes = Math.floor(total / 60)
+  return `${minutes}:${String(total % 60).padStart(2, "0")}`
+}
+
+function ArtifactToolbar(props: {
+  mode?: ArtifactMode
+  onModeChange?: (mode: ArtifactMode) => void
+  meta: string[]
+  actions?: JSX.Element
+}) {
+  const language = useLanguage()
+  return (
+    <div data-slot="artifact-toolbar" class="flex h-10 shrink-0 items-center gap-3 px-4">
+      <Show when={props.onModeChange}>
+        <SegmentedControl
+          value={props.mode ?? "preview"}
+          onChange={(value) => {
+            if (value === "preview" || value === "source") props.onModeChange?.(value)
+          }}
+        >
+          <SegmentedControlItem value="preview">{language.t("file.view.preview")}</SegmentedControlItem>
+          <SegmentedControlItem value="source">{language.t("file.view.source")}</SegmentedControlItem>
+        </SegmentedControl>
+      </Show>
+      <div class="ms-auto flex min-w-0 items-center gap-3">
+        <div class="flex min-w-0 items-center gap-2 text-12-regular text-text-weak">
+          <For each={props.meta}>
+            {(item, index) => (
+              <>
+                <Show when={index() > 0}>
+                  <span aria-hidden class="text-text-faint">
+                    ·
+                  </span>
+                </Show>
+                <span class="truncate tabular-nums">{item}</span>
+              </>
+            )}
+          </For>
+        </div>
+        {props.actions}
+      </div>
+    </div>
+  )
+}
+
+function OpenInBrowserButton(props: { path: string }) {
+  const language = useLanguage()
+  const artifacts = useArtifactOpener()
+  return (
+    <Show when={artifacts.canOpenInBrowser(props.path)}>
+      <Button size="small" variant="ghost" icon="globe" onClick={() => artifacts.openInBrowser(props.path)}>
+        {language.t("file.view.openInBrowser")}
+      </Button>
+    </Show>
+  )
+}
+
+function createBlobUrl(content: () => FileContent) {
+  return createMemo(() => {
+    const value = blobUrlFromContent(content())
+    onCleanup(() => URL.revokeObjectURL(value))
+    return value
+  })
+}
+
+/** Images and SVG previews: fit the pane, click to inspect at 1:1 when the image is larger. */
+function ArtifactImage(props: MediaProps) {
+  const url = createBlobUrl(() => props.content)
+  const [state, setState] = createStore({ zoom: "fit" as "fit" | "actual", overflow: false, width: 0, height: 0 })
+  let stage: HTMLDivElement | undefined
+  const measure = () => {
+    if (!stage) return
+    setState("overflow", state.width > stage.clientWidth - 48 || state.height > stage.clientHeight - 48)
+  }
+  createResizeObserver(
+    () => stage,
+    () => measure(),
+  )
+  createEffect(() => {
+    url()
+    setState({ zoom: "fit", overflow: false })
+  })
+  return (
+    <div
+      ref={stage}
+      data-slot="artifact-stage"
+      data-checker
+      data-zoom={state.zoom}
+      data-overflow={state.overflow || undefined}
+      class="relative min-h-0 flex-1 overflow-auto"
+    >
+      <div
+        classList={{
+          "absolute inset-0 flex items-center justify-center p-6": state.zoom === "fit",
+          "flex min-h-full min-w-full w-max items-center justify-center p-6": state.zoom === "actual",
+        }}
+      >
+        <img
+          data-slot="artifact-media"
+          src={url()}
+          alt={getFilename(props.path)}
+          draggable={false}
+          onError={() => props.onError()}
+          onLoad={(event) => {
+            const image = event.currentTarget
+            setState({ width: image.naturalWidth, height: image.naturalHeight })
+            props.onInfo({ width: image.naturalWidth, height: image.naturalHeight })
+            measure()
+          }}
+          onClick={() => {
+            if (!state.overflow && state.zoom === "fit") return
+            setState("zoom", state.zoom === "fit" ? "actual" : "fit")
+          }}
+        />
+      </div>
+    </div>
+  )
+}
+
+function ArtifactVideo(props: MediaProps) {
+  const url = createBlobUrl(() => props.content)
+  return (
+    <div data-slot="artifact-stage" data-zoom="fit" class="relative min-h-0 flex-1 overflow-hidden">
+      <div class="absolute inset-0 flex items-center justify-center p-6">
+        <video
+          data-slot="artifact-media"
+          class="w-full bg-black"
+          controls
+          preload="metadata"
+          playsinline
+          onError={() => props.onError()}
+          src={url()}
+          onLoadedMetadata={(event) => {
+            const video = event.currentTarget
+            props.onInfo({ width: video.videoWidth, height: video.videoHeight, duration: video.duration })
+          }}
+        />
+      </div>
+    </div>
+  )
+}
+
+function ArtifactAudio(props: MediaProps) {
+  const url = createBlobUrl(() => props.content)
+  return (
+    <div data-slot="artifact-stage" class="relative min-h-0 flex-1 overflow-auto">
+      <div class="absolute inset-0 flex items-center justify-center p-6">
+        <div class="flex w-full max-w-lg flex-col items-center gap-5 rounded-xl border border-v2-border-border-muted bg-v2-background-bg-base px-8 py-8 shadow-[var(--v2-elevation-raised)]">
+          <div class="flex size-14 items-center justify-center rounded-full bg-v2-background-bg-layer-02">
+            <FileIcon node={{ path: props.path, type: "file" }} class="size-7" />
+          </div>
+          <div class="max-w-full truncate text-14-medium text-text-strong">{getFilename(props.path)}</div>
+          <audio
+            class="w-full"
+            onError={() => props.onError()}
+            controls
+            preload="metadata"
+            src={url()}
+            onLoadedMetadata={(event) => props.onInfo({ duration: event.currentTarget.duration })}
+          />
+        </div>
+      </div>
+    </div>
+  )
+}
+
+function ArtifactFrame(props: { path: string; content: FileContent; kind: "pdf" | "html" }) {
+  const url = createBlobUrl(() => props.content)
+  // PDF Open Parameters: start with the thumbnail pane closed and the page fitted to the pane width.
+  const src = () => (props.kind === "pdf" ? `${url()}#navpanes=0&view=FitH` : url())
+  return (
+    <iframe
+      class="block h-full w-full flex-1 border-0 bg-white"
+      title={getFilename(props.path)}
+      src={src()}
+      // The PDF viewer is Chromium's own and does not run in a sandboxed frame. HTML runs as an
+      // opaque origin: no app storage, cookies, or credentialed requests reach it.
+      sandbox={props.kind === "html" ? "allow-scripts allow-popups allow-forms allow-modals" : undefined}
+      referrerPolicy="no-referrer"
+    />
+  )
+}
+
+function ArtifactMarkdown(props: { path: string; text: string; cacheKey?: string }) {
+  const parent = useMarkdown()
+  const artifacts = useArtifactOpener()
+  // getDirectory yields "/" for a root-level file, which would make relative links absolute.
+  const dir = createMemo(() => (props.path.includes("/") || props.path.includes("\\") ? getDirectory(props.path) : ""))
+  // Absolute references bypass the file's directory; relative ones resolve against it.
+  const resolve = (href: string) => (/^([a-z]:)?\//i.test(href) ? href : (resolveArtifactPath(dir(), href) ?? href))
+  return (
+    <MarkdownProvider
+      readImage={(src, signal) => parent?.readImage?.(resolve(src), signal) ?? Promise.resolve(undefined)}
+      openLocalFile={(href) => artifacts.open(href, dir())}
+    >
+      <div class="mx-auto w-full max-w-3xl px-8 py-6">
+        <Markdown text={props.text} cacheKey={props.cacheKey} class="select-text" />
+      </div>
+    </MarkdownProvider>
+  )
+}
+
+/** Mermaid sources render through the same fenced-block pipeline the timeline uses. */
+function ArtifactMermaid(props: { text: string; cacheKey?: string }) {
+  return (
+    <div class="mx-auto w-full max-w-4xl px-8 py-6">
+      <Markdown text={`\`\`\`mermaid\n${props.text}\n\`\`\``} cacheKey={props.cacheKey} class="select-text" />
+    </div>
+  )
+}
+
+function ArtifactTable(props: { path: string; text: string; onInfo: (info: ArtifactInfo) => void }) {
+  const language = useLanguage()
+  const parsed = createMemo(() => parseDelimited(props.text, props.path.toLowerCase().endsWith(".tsv") ? "\t" : ","))
+  createEffect(() => props.onInfo({ rows: parsed().total, columns: parsed().columns }))
+  // Pad the header to the widest row so no data column is dropped.
+  const header = () => Array.from({ length: parsed().columns }, (_, index) => parsed().rows[0]?.[index] ?? "")
+  const body = () => parsed().rows.slice(1)
+  return (
+    <div class="min-h-0 flex-1 overflow-auto">
+      <table data-slot="artifact-table" class="min-w-full text-13-regular text-text-base">
+        <thead>
+          <tr>
+            <th data-index />
+            <For each={header()}>{(cell) => <th>{cell}</th>}</For>
+          </tr>
+        </thead>
+        <tbody>
+          <For each={body()}>
+            {(row, index) => (
+              <tr>
+                <td data-index>{index() + 1}</td>
+                <For each={header()}>{(_, column) => <td>{row[column()] ?? ""}</td>}</For>
+              </tr>
+            )}
+          </For>
+        </tbody>
+      </table>
+      <Show when={parsed().total > parsed().rows.length}>
+        <div class="px-4 py-3 text-12-regular text-text-weak">
+          {language.t("file.view.table.truncated", { shown: parsed().rows.length - 1, total: parsed().total - 1 })}
+        </div>
+      </Show>
+    </div>
+  )
+}
+
+const specimenSizes = [12, 16, 24, 40, 64]
+
+function ArtifactFont(props: { path: string; content: FileContent }) {
+  const language = useLanguage()
+  const url = createBlobUrl(() => props.content)
+  const family = createMemo(() => `artifact-${Math.random().toString(36).slice(2)}`)
+  createEffect(() => {
+    const face = new FontFace(family(), `url(${url()})`)
+    document.fonts.add(face)
+    void face.load().catch(() => undefined)
+    onCleanup(() => document.fonts.delete(face))
+  })
+  return (
+    <div class="min-h-0 flex-1 overflow-auto">
+      <div class="mx-auto flex w-full max-w-3xl flex-col gap-6 px-8 py-8" style={{ "font-family": `"${family()}"` }}>
+        <div class="text-text-strong" style={{ "font-size": "56px", "line-height": "1.1" }}>
+          {getFilename(props.path).replace(/\.[^.]+$/, "")}
+        </div>
+        <div class="break-all text-text-base" style={{ "font-size": "22px", "line-height": "1.4" }}>
+          ABCDEFGHIJKLMNOPQRSTUVWXYZ
+          <br />
+          abcdefghijklmnopqrstuvwxyz
+          <br />
+          0123456789 !?&@#%(){}[]
+        </div>
+        <div class="flex flex-col gap-3 border-t border-v2-border-border-muted pt-6">
+          <For each={specimenSizes}>
+            {(size) => (
+              <div class="flex items-baseline gap-4">
+                <span
+                  class="w-8 shrink-0 text-12-regular text-text-faint tabular-nums"
+                  style={{ "font-family": "var(--font-family-mono)" }}
+                >
+                  {size}
+                </span>
+                <span class="text-text-base" style={{ "font-size": `${size}px`, "line-height": "1.25" }}>
+                  {language.t("file.view.fontSample")}
+                </span>
+              </div>
+            )}
+          </For>
+        </div>
+      </div>
+    </div>
+  )
+}
+
+function ArtifactBinary(props: { path: string; size: string }) {
+  const language = useLanguage()
+  return (
+    <div data-slot="artifact-stage" class="relative min-h-0 flex-1">
+      <div class="absolute inset-0 flex flex-col items-center justify-center gap-3 p-6 text-center">
+        <FileIcon node={{ path: props.path, type: "file" }} class="size-8 text-text-weak" />
+        <div class="text-14-medium text-text-strong">{getFilename(props.path)}</div>
+        <div class="text-13-regular text-text-weak">{language.t("file.view.binary", { size: props.size })}</div>
+      </div>
+    </div>
+  )
+}
@@ -1,4 +1,4 @@
-import { createEffect, createMemo, createSignal, Match, on, onCleanup, Switch } from "solid-js"
+import { createEffect, createMemo, createSignal, Match, on, onCleanup, Show, Switch } from "solid-js"
 import { createStore } from "solid-js/store"
 import { Dynamic } from "solid-js/web"
 import { makeEventListener } from "@solid-primitives/event-listener"
@@ -11,8 +11,9 @@ import { LineCommentOverflowIcon } from "@opencode/ui/line-comment"
 import { Menu } from "@opencode/ui/menu"
 import { Tabs } from "@opencode/ui/tabs"
 import { ScrollView } from "@opencode/ui/scroll-view"
-import { showToast } from "@/shell/notifications/toast"
 import { selectionFromLines, useFile, type FileSelection, type SelectedLineRange } from "@/workspaces/files/model"
+import { artifactKind } from "@/workspaces/files/artifact"
+import { ArtifactView } from "@/session/files/artifact-view"
 import { useComments } from "@/composer/comments"
 import { useLanguage } from "@/runtime/i18n/language"
 import { useComposerState } from "@/composer/persistence"
@@ -205,6 +206,11 @@ export function SessionFileView(props: SessionFileViewProps) {
  })
  const contents = createMemo(() => state()?.content?.content ?? "")
  const cacheKey = createMemo(() => sampledChecksum(contents()))
+  // Plain text keeps the code view; every other kind is rendered by ArtifactView.
+  const artifact = createMemo(() => {
+    const content = state()?.content
+    return content?.type === "binary" || artifactKind(path() ?? "") !== "text"
+  })
  const selectedLines = createMemo<SelectedLineRange | null>(() => {
    const p = path()
    if (!p) return null
@@ -433,39 +439,42 @@ export function SessionFileView(props: SessionFileViewProps) {
        }}
        search={search}
        class="select-text"
-        media={{
-          mode: "auto",
-          path: path(),
-          current: state()?.content,
-          onLoad: scrollSync.queueRestore,
-          onError: (args: { kind: "image" | "audio" | "svg" }) => {
-            if (args.kind !== "svg") return
-            showToast({
-              variant: "error",
-              title: language.t("toast.file.loadFailed.title"),
-            })
-          },
-        }}
+        // Media and previews have their own viewers below; the code view only ever shows text.
+        media={{ mode: "off" }}
      />
    </div>
  )

+  // The code view scrolls inside ScrollView so line state and scroll position persist per tab.
+  const codeView = (source: string) => (
+    <ScrollView class="min-h-0 flex-1" viewportRef={scrollSync.setViewport} onScroll={scrollSync.handleScroll}>
+      {renderFile(source)}
+    </ScrollView>
+  )
+
  const content = () => (
-    <div class="mt-3 relative h-full min-h-0">
-      <ScrollView class="h-full" viewportRef={scrollSync.setViewport} onScroll={scrollSync.handleScroll}>
-        <Switch>
-          <Match when={state()?.loaded}>{renderFile(contents())}</Match>
-          <Match when={state()?.loading}>
-            <div class="px-6 py-4 text-text-weak">{language.t("common.loading")}…</div>
-          </Match>
-          <Match when={state()?.notFound ? state()?.name : undefined}>
-            {(name) => (
-              <div class="px-6 py-4 text-text-weak">{language.t("file.error.notFound", { name: name() })}</div>
-            )}
-          </Match>
-          <Match when={state()?.error}>{(err) => <div class="px-6 py-4 text-text-weak">{err()}</div>}</Match>
-        </Switch>
-      </ScrollView>
+    <div class="mt-3 relative h-full min-h-0 flex flex-col">
+      <Switch>
+        <Match when={state()?.loaded ? state()?.content : undefined}>
+          {(value) => (
+            <Show when={artifact()} fallback={codeView(value().content)}>
+              <ArtifactView
+                path={path() ?? ""}
+                content={value()}
+                cacheKey={cacheKey()}
+                source={codeView(value().content)}
+              />
+            </Show>
+          )}
+        </Match>
+        <Match when={state()?.loading}>
+          <div class="px-6 py-4 text-text-weak">{language.t("common.loading")}…</div>
+        </Match>
+        <Match when={state()?.notFound ? state()?.name : undefined}>
+          {(name) => <div class="px-6 py-4 text-text-weak">{language.t("file.error.notFound", { name: name() })}</div>}
+        </Match>
+        <Match when={state()?.error}>{(err) => <div class="px-6 py-4 text-text-weak">{err()}</div>}</Match>
+      </Switch>
    </div>
  )

@@ -0,0 +1,105 @@
+import { createEffect, onCleanup, type ParentProps } from "solid-js"
+import { createSimpleContext } from "@opencode/ui/context"
+import { MarkdownProvider, useMarkdown } from "@opencode/session-ui/context/markdown"
+import { useBrowserAttachments } from "@/session/browser/attachments"
+import type { SessionModel } from "@/session/model"
+import { useFile } from "@/workspaces/files/model"
+import { artifactKind, resolveArtifactPath } from "@/workspaces/files/artifact"
+import { encodeFilePath } from "@/workspaces/files/path"
+import { useWorkspaceLocation } from "@/workspaces/location"
+import { useServer } from "@/runtime/server/current"
+import { ServerConnection } from "@/runtime/server/registry"
+import { useSessionLayout } from "@/session/session-layout"
+import { createOpenSessionFileTab } from "@/session/helpers"
+import type { createSessionBrowser } from "@/session/browser/model"
+
+/** Routes local links in timeline markdown to the artifact opener while keeping image loading. */
+export function ArtifactMarkdownProvider(props: ParentProps) {
+  const markdown = useMarkdown()
+  const artifacts = useArtifactOpener()
+  return (
+    <MarkdownProvider readImage={markdown?.readImage} openLocalFile={(path) => artifacts.open(path)}>
+      {props.children}
+    </MarkdownProvider>
+  )
+}
+
+/**
+ * Opens files the agent references as side-panel tabs, inside or outside the workspace, or as
+ * a browser tab for HTML when the desktop can load the file directly.
+ */
+export const { use: useArtifactOpener, provider: ArtifactOpenerProvider } = createSimpleContext({
+  name: "ArtifactOpener",
+  init: (props: { session: SessionModel; browser: ReturnType<typeof createSessionBrowser> }) => {
+    const file = useFile()
+    const server = useServer()
+    const location = useWorkspaceLocation()
+    const attachments = useBrowserAttachments()
+    const { tabs, view } = useSessionLayout()
+
+    const root = () => location().directory.replaceAll("\\", "/").replace(/\/+$/, "")
+
+    /**
+     * Turn a link into a path `useFile` can load: workspace-relative when it is under the root,
+     * otherwise absolute. Relative links resolve against `base`; ones that climb past the root
+     * become absolute too, so a `../../shared/report.pdf` still opens.
+     */
+    const resolve = (href: string, base?: string) => {
+      // Agents cite locations as path:line or path:line:col; the file is what opens.
+      const value = href.replaceAll("\\", "/").replace(/:\d+(?::\d+)?$/, "")
+      if (/^[a-z]:\//i.test(value) || value.startsWith("/")) return file.normalize(value)
+      const relative = resolveArtifactPath(base ?? "", value)
+      if (relative !== undefined) return file.normalize(relative)
+      // Climbing past the workspace root: resolve from the referencing folder's absolute location.
+      const dir = base ? `${root()}/${base.replace(/\/+$/, "")}` : root()
+      return file.normalize(resolveArtifactPath(dir, value) ?? value)
+    }
+
+    const showTab = createOpenSessionFileTab({
+      normalizeTab: (tab) => tab,
+      openTab: (tab) => tabs().open(tab),
+      pathFromTab: file.pathFromTab,
+      loadFile: () => undefined,
+      openReviewPanel: () => {
+        if (!view().reviewPanel.opened()) view().reviewPanel.open()
+      },
+      setActive: (tab) => tabs().setActive(tab),
+    })
+
+    // Inline paths are guessed from text, so confirm the file exists before a tab appears for it.
+    const openTab = (path: string) => {
+      void file.load(path).then(() => {
+        if (file.get(path)?.loaded) showTab(file.tab(path))
+      })
+    }
+
+    // The desktop's own sidecar shares this disk, and its browser pane accepts file:// URLs inside the
+    // session workspace only. Forwarded loopback servers do not qualify, matching the desktop policy.
+    const canOpenInBrowser = (path?: string) =>
+      ServerConnection.builtin(server.conn) &&
+      props.browser.available() &&
+      props.browser.attached() &&
+      (path === undefined || !file.absolute(path))
+
+    const openInBrowser = (path: string) => {
+      props.browser.command({ type: "tabs.open", url: `file://${encodeFilePath(`${root()}/${path}`)}` })
+    }
+
+    /** Open `href` as referenced from `base` (a workspace-relative directory, "" for the root). */
+    const open = (href: string, base?: string) => {
+      const path = resolve(href, base)
+      if (!path) return
+      if (artifactKind(path) === "html" && canOpenInBrowser(path)) return openInBrowser(path)
+      openTab(path)
+    }
+
+    // The agent's browser.preview tool arrives through the desktop browser pane attachment.
+    createEffect(() => {
+      const sessionID = props.session.identity.sessionID()
+      if (!sessionID) return
+      onCleanup(attachments.onPreview(server, sessionID, (path) => open(path)))
+    })
+
+    return { canOpenInBrowser, openInBrowser, open }
+  },
+})
@@ -173,7 +173,9 @@ export function SessionFileBrowserTab(props: {
          <SessionFilePanelV2Empty>
            <div class="flex flex-col items-center gap-2 text-center text-text-weak">
              <Icon name="file-tree" size="large" class="mb-2" />
-              <div class="text-[13px] font-medium leading-[13px] text-text-strong">{language.t("command.file.open")}</div>
+              <div class="text-[13px] font-medium leading-[13px] text-text-strong">
+                {language.t("command.file.open")}
+              </div>
              <div class="h-5 text-13-regular leading-5">{language.t("session.files.selectToOpen")}</div>
            </div>
          </SessionFilePanelV2Empty>
@@ -1,6 +1,8 @@
 import { children, createMemo, Show } from "solid-js"
 import type { JSX } from "solid-js"
 import { useSortable } from "@dnd-kit/solid/sortable"
+import { Icon } from "@opencode/ui/icon"
+import { IconButton } from "@opencode/ui/icon-button"
 import { Keybind } from "@opencode/ui/keybind"
 import { Tooltip } from "@opencode/ui/tooltip"
 import { Tabs } from "@opencode/ui/tabs"
@@ -69,9 +71,19 @@ export function SortableTab(props: {
              placement="bottom"
              gutter={10}
            >
-              <Tabs.CloseButton
-                class="h-5 w-5"
-                onClick={() => props.onTabClose(props.tab)}
+              <IconButton
+                size="small"
+                variant="ghost-muted"
+                onPointerDown={(event) => {
+                  event.preventDefault()
+                  event.stopPropagation()
+                }}
+                onClick={(event) => {
+                  event.preventDefault()
+                  event.stopPropagation()
+                  props.onTabClose(props.tab)
+                }}
+                icon={<Icon name="xmark-small" />}
                aria-label={language.t("common.closeTab")}
              />
            </Tooltip>
@@ -137,6 +137,7 @@ export function useSessionModel() {
      tabs: layout.tabs,
      view: layout.view,
      tabKey: layout.tabKey,
+      sessionKey: layout.sessionKey,
    },
    ownership: createSessionOwnership(layout.sessionKey),
    tabs: {
@@ -155,6 +155,9 @@ export function createSessionReview(input: {
  const count = () => diffs().length
  const hasChanges = () => count() > 0
  const ready = () => {
+    // A project without VCS never enables vcsQuery, so its status stays "pending" forever.
+    const project = input.session.project()
+    if (project && !project.vcs) return true
    if (mode() === "git" || mode() === "branch") return !vcsQuery.isPending
    return true
  }
@@ -249,7 +249,7 @@ function ReviewTitle(props: { review: SessionReviewModel }) {
 function ReviewEmpty(props: { review: SessionReviewModel; loadingClass: string }) {
  const language = useLanguage()
  const loading = () => (props.review.mode() === "git" || props.review.mode() === "branch") && !props.review.ready()
-  const noGit = () => props.review.mode() === "turn" && props.review.noGit()
+  const noGit = () => props.review.noGit()
  const text = () => {
    if (props.review.mode() === "git") return language.t("session.review.noUncommittedChanges")
    if (props.review.mode() === "branch") return language.t("session.review.noBranchChanges")
@@ -282,7 +282,7 @@ function ReviewEmpty(props: { review: SessionReviewModel; loadingClass: string }
 function ReviewPanelEmpty(props: { review: SessionReviewModel }) {
  const language = useLanguage()
  const loading = () => (props.review.mode() === "git" || props.review.mode() === "branch") && !props.review.ready()
-  const noGit = () => props.review.mode() === "turn" && props.review.noGit()
+  const noGit = () => props.review.noGit()
  return (
    <Switch>
      <Match when={loading()}>
@@ -38,6 +38,7 @@ import { SessionReviewToggle } from "./header/session-header-actions"
 import { createAnimatedPresence } from "@/runtime/animated-presence"
 import { createSessionBrowser } from "./browser/model"
 import { createTimelineCache } from "./timeline/cache"
+import { ArtifactMarkdownProvider, ArtifactOpenerProvider } from "./files/open-artifact"

 const SessionMobileFiles = lazy(async () => {
  const { SessionMobileFiles } = await import("./files/session-mobile-files")
@@ -50,14 +51,26 @@ const SessionSummaryPanel = lazy(async () => {
 })

 export function SessionScreen(props: { session: SessionModel }) {
+  // The timeline cache captures its owner when created, so link handling must be provided above it.
+  const browser = createSessionBrowser(props.session)
+  return (
+    <ArtifactOpenerProvider session={props.session} browser={browser}>
+      <ArtifactMarkdownProvider>
+        <SessionScreenContent session={props.session} browser={browser} />
+      </ArtifactMarkdownProvider>
+    </ArtifactOpenerProvider>
+  )
+}
+
+function SessionScreenContent(props: { session: SessionModel; browser: ReturnType<typeof createSessionBrowser> }) {
  const session = props.session
+  const browser = props.browser
  const server = useServer()
  const detailsProject = createMemo(() => {
    const info = session.data.info()
    return info ? projectForSession(info, server.ctx.sync.data.project) : undefined
  })
  const isDesktop = session.isDesktop
-  const browser = createSessionBrowser(session)
  const screen = createSessionScreenLayout(session)
  const timeline = createSessionTimelineInteraction(session)
  const timelineSearch = createTimelineSearchController({
@@ -1102,10 +1102,6 @@
  padding-block: 20px;
 }

-.settings-server-connection .settings-servers-lead {
-  gap: 4px;
-}
-
 .settings-servers-row:not(:last-child) {
  padding-bottom: 16px;
  margin-bottom: 16px;
@@ -9,7 +9,8 @@
  justify-content: center;
 }

-[data-titlebar-tab] {
+[data-titlebar-tab],
+[data-titlebar-tab-action] {
  --tab-base: var(--v2-background-bg-deep);
  --tab-overlay: transparent;
  background: linear-gradient(var(--tab-overlay), var(--tab-overlay)), var(--tab-base);
@@ -68,6 +69,14 @@
  --tab-overlay: var(--v2-overlay-simple-overlay-pressed);
 }

+[data-titlebar-tab-action]:is(:hover, :focus-visible) {
+  --tab-overlay: var(--v2-overlay-simple-overlay-hover);
+}
+
+[data-titlebar-tab-action]:is(:active, [data-state="pressed"]) {
+  --tab-overlay: var(--v2-overlay-simple-overlay-pressed);
+}
+
 [data-titlebar-tab]:is(:hover, [data-state="pressed"]) [data-slot="tab-close"] {
  background: linear-gradient(var(--tab-overlay), var(--tab-overlay)), var(--tab-base);
 }
@@ -351,9 +351,10 @@ export function Titlebar(props: {
              >
                <button
                  type="button"
+                  data-titlebar-tab-action
                  data-action="vertical-tabs-home"
                  data-state={layout.route().type === "home" ? "pressed" : undefined}
-                  class="group mb-1 flex h-7 w-full shrink-0 items-center gap-1.5 rounded-[6px] ps-1.5 pe-2 text-[13px] leading-4 text-v2-text-text-faint hover:bg-v2-background-bg-layer-02 hover:text-v2-text-text-base data-[state=pressed]:bg-v2-background-bg-layer-02 data-[state=pressed]:text-v2-text-text-base"
+                  class="group mb-1 flex h-7 w-full shrink-0 items-center gap-1.5 rounded-[6px] ps-1.5 pe-2 text-[13px] leading-4 text-v2-text-text-faint hover:text-v2-text-text-base data-[state=pressed]:text-v2-text-text-base"
                  onClick={toggleHome}
                  aria-label={language.t("home.title")}
                  aria-pressed={layout.route().type === "home"}
@@ -650,8 +651,9 @@ export function Titlebar(props: {
                            {homeButton(true)}
                            <button
                              type="button"
+                              data-titlebar-tab-action
                              data-action="vertical-tabs-new-session"
-                              class="group flex h-7 w-full shrink-0 items-center gap-1.5 rounded-[6px] ps-1.5 pe-2 text-[13px] leading-4 text-v2-text-text-faint hover:bg-v2-background-bg-layer-02 hover:text-v2-text-text-base"
+                              class="group flex h-7 w-full shrink-0 items-center gap-1.5 rounded-[6px] ps-1.5 pe-2 text-[13px] leading-4 text-v2-text-text-faint hover:text-v2-text-text-base"
                              onClick={openNewTab}
                              aria-label={language.t("command.session.new")}
                            >
@@ -0,0 +1,118 @@
+import { describe, expect, test } from "bun:test"
+import {
+  artifactKind,
+  bytesToBase64,
+  contentBytes,
+  fileContentFromBytes,
+  MAX_MEDIA_BYTES,
+  parseDelimited,
+  resolveArtifactPath,
+} from "./artifact"
+
+describe("artifactKind", () => {
+  test.each([
+    ["shot.PNG", "image"],
+    ["logo.svg", "svg"],
+    ["song.mp3", "audio"],
+    ["demo.mp4", "video"],
+    ["clip.webm", "video"],
+    ["paper.pdf", "pdf"],
+    ["out/index.html", "html"],
+    ["README.md", "markdown"],
+    ["flow.mmd", "mermaid"],
+    ["data.csv", "table"],
+    ["data.tsv", "table"],
+    ["Inter.woff2", "font"],
+    ["src/app.ts", "text"],
+    ["Makefile", "text"],
+    [".env", "text"],
+    ["archive.tar.gz", "text"],
+  ] as const)("classifies %s as %s", (path, kind) => {
+    expect(artifactKind(path)).toBe(kind)
+  })
+})
+
+describe("fileContentFromBytes", () => {
+  test("keeps media as base64 with a mime type", () => {
+    const content = fileContentFromBytes("a.png", new Uint8Array([137, 80, 78, 71]))
+    expect(content).toEqual({ type: "binary", content: "iVBORw==", encoding: "base64", mimeType: "image/png" })
+  })
+
+  test("decodes text and svg with a mime type", () => {
+    expect(fileContentFromBytes("a.svg", new TextEncoder().encode("<svg/>"))).toEqual({
+      type: "text",
+      content: "<svg/>",
+      mimeType: "image/svg+xml",
+    })
+    expect(fileContentFromBytes("a.ts", new TextEncoder().encode("const a = 1"))).toEqual({
+      type: "text",
+      content: "const a = 1",
+      mimeType: undefined,
+    })
+  })
+
+  test("keeps only the size of media above the cap", () => {
+    const content = fileContentFromBytes("big.mp4", new Uint8Array(MAX_MEDIA_BYTES + 1))
+    expect(content).toEqual({ type: "binary", content: "", size: MAX_MEDIA_BYTES + 1 })
+  })
+
+  test("marks unknown binaries without keeping bytes", () => {
+    expect(fileContentFromBytes("a.bin", new Uint8Array([1, 0, 2]))).toEqual({ type: "binary", content: "", size: 3 })
+  })
+
+  test("encodes large buffers in chunks", () => {
+    const bytes = new Uint8Array(70_000).fill(65)
+    expect(bytesToBase64(bytes)).toBe(Buffer.from(bytes).toString("base64"))
+  })
+})
+
+describe("contentBytes", () => {
+  test("recovers byte counts from base64 and text", () => {
+    expect(contentBytes({ type: "binary", content: "iVBORw==", encoding: "base64" })).toBe(4)
+    expect(contentBytes({ type: "binary", content: "iVBORwA=", encoding: "base64" })).toBe(5)
+    expect(contentBytes({ type: "text", content: "héllo" })).toBe(6)
+  })
+})
+
+describe("parseDelimited", () => {
+  test("handles quotes, embedded delimiters, newlines, and CRLF", () => {
+    const parsed = parseDelimited('name,note\r\n"Smith, J","says ""hi""\nand more"\nplain,\n', ",")
+    expect(parsed.rows).toEqual([
+      ["name", "note"],
+      ["Smith, J", 'says "hi"\nand more'],
+      ["plain", ""],
+    ])
+    expect(parsed.total).toBe(3)
+    expect(parsed.columns).toBe(2)
+  })
+
+  test("counts rows past the limit without keeping them", () => {
+    const parsed = parseDelimited("a\tb\n1\t2\n3\t4\n5\t6", "\t", 2)
+    expect(parsed.rows).toHaveLength(2)
+    expect(parsed.total).toBe(4)
+  })
+})
+
+describe("resolveArtifactPath", () => {
+  test.each([
+    ["docs", "guide.md", "docs/guide.md"],
+    ["docs", "./img/a.png", "docs/img/a.png"],
+    ["docs/api", "../index.md", "docs/index.md"],
+    ["", "src/app.ts", "src/app.ts"],
+    ["docs", "sub\\win.md", "docs/sub/win.md"],
+    ["", "docs/guide.md", "docs/guide.md"],
+    ["/tmp/notes/", "../out/a.pdf", "/tmp/out/a.pdf"],
+    ["C:/tmp/notes/", "img.png", "C:/tmp/notes/img.png"],
+    ["/repo", "../shared/report.pdf", "/shared/report.pdf"],
+  ])("resolves %s + %s", (base, href, expected) => {
+    expect(resolveArtifactPath(base, href)).toBe(expected)
+  })
+
+  test.each([
+    ["docs", "../../etc/passwd"],
+    ["", "../x"],
+    ["docs", "/abs/path"],
+  ])("rejects %s + %s", (base, href) => {
+    expect(resolveArtifactPath(base, href)).toBeUndefined()
+  })
+})
@@ -0,0 +1,211 @@
+import type { FileContent } from "@/runtime/server/types"
+
+export type ArtifactKind =
+  | "image"
+  | "svg"
+  | "audio"
+  | "video"
+  | "pdf"
+  | "html"
+  | "markdown"
+  | "mermaid"
+  | "table"
+  | "font"
+  | "text"
+
+const mimes = new Map([
+  ["png", "image/png"],
+  ["jpg", "image/jpeg"],
+  ["jpeg", "image/jpeg"],
+  ["gif", "image/gif"],
+  ["webp", "image/webp"],
+  ["avif", "image/avif"],
+  ["bmp", "image/bmp"],
+  ["ico", "image/x-icon"],
+  ["tif", "image/tiff"],
+  ["tiff", "image/tiff"],
+  ["heic", "image/heic"],
+  ["svg", "image/svg+xml"],
+  ["mp3", "audio/mpeg"],
+  ["wav", "audio/wav"],
+  ["ogg", "audio/ogg"],
+  ["oga", "audio/ogg"],
+  ["m4a", "audio/mp4"],
+  ["aac", "audio/aac"],
+  ["flac", "audio/flac"],
+  ["opus", "audio/ogg"],
+  ["weba", "audio/webm"],
+  ["mp4", "video/mp4"],
+  ["m4v", "video/mp4"],
+  ["webm", "video/webm"],
+  ["mov", "video/quicktime"],
+  ["ogv", "video/ogg"],
+  ["mkv", "video/x-matroska"],
+  ["pdf", "application/pdf"],
+  ["html", "text/html"],
+  ["htm", "text/html"],
+  ["md", "text/markdown"],
+  ["markdown", "text/markdown"],
+  ["mdx", "text/markdown"],
+  ["mmd", "text/vnd.mermaid"],
+  ["mermaid", "text/vnd.mermaid"],
+  ["csv", "text/csv"],
+  ["tsv", "text/tab-separated-values"],
+  ["ttf", "font/ttf"],
+  ["otf", "font/otf"],
+  ["woff", "font/woff"],
+  ["woff2", "font/woff2"],
+])
+
+export function artifactExtension(path: string) {
+  const name = path.split(/[\\/]/).pop() ?? ""
+  const index = name.lastIndexOf(".")
+  if (index <= 0) return ""
+  return name.slice(index + 1).toLowerCase()
+}
+
+export function artifactMime(path: string) {
+  return mimes.get(artifactExtension(path))
+}
+
+export function artifactKind(path: string): ArtifactKind {
+  const mime = artifactMime(path)
+  if (!mime) return "text"
+  if (mime === "image/svg+xml") return "svg"
+  if (mime === "application/pdf") return "pdf"
+  if (mime === "text/html") return "html"
+  if (mime === "text/markdown") return "markdown"
+  if (mime === "text/vnd.mermaid") return "mermaid"
+  if (mime === "text/csv" || mime === "text/tab-separated-values") return "table"
+  if (mime.startsWith("image/")) return "image"
+  if (mime.startsWith("audio/")) return "audio"
+  if (mime.startsWith("font/")) return "font"
+  return "video"
+}
+
+/** Kinds whose bytes are kept as base64 so media elements can play them without a text round trip. */
+const binaryKinds = new Set<ArtifactKind>(["image", "audio", "video", "pdf", "font"])
+
+/** Text files never contain NUL; a NUL in the first 8 KiB marks an unknown binary. */
+function isBinaryBytes(bytes: Uint8Array) {
+  return bytes.subarray(0, 8192).includes(0)
+}
+
+export function bytesToBase64(bytes: Uint8Array) {
+  const parts: string[] = []
+  for (let index = 0; index < bytes.length; index += 0x8000) {
+    parts.push(String.fromCharCode(...bytes.subarray(index, index + 0x8000)))
+  }
+  return btoa(parts.join(""))
+}
+
+/** Media above this stays a placeholder: base64 encoding on the main thread and the LRU budget both suffer. */
+export const MAX_MEDIA_BYTES = 25 * 1024 * 1024
+
+export function fileContentFromBytes(path: string, bytes: Uint8Array): FileContent {
+  const kind = artifactKind(path)
+  const mimeType = artifactMime(path)
+  if (binaryKinds.has(kind)) {
+    if (bytes.length > MAX_MEDIA_BYTES) return { type: "binary", content: "", size: bytes.length }
+    return { type: "binary", content: bytesToBase64(bytes), encoding: "base64", mimeType }
+  }
+  // Unknown binaries keep no bytes: the viewer only shows a placeholder for them.
+  if (kind === "text" && isBinaryBytes(bytes)) return { type: "binary", content: "", size: bytes.length }
+  return { type: "text", content: new TextDecoder().decode(bytes), mimeType }
+}
+
+/** Approximate on-disk size of loaded content. */
+export function contentBytes(content: FileContent) {
+  if (content.size !== undefined) return content.size
+  if (content.encoding === "base64") {
+    const padding = content.content.endsWith("==") ? 2 : content.content.endsWith("=") ? 1 : 0
+    return Math.floor((content.content.length * 3) / 4) - padding
+  }
+  return new TextEncoder().encode(content.content).length
+}
+
+/**
+ * Parse RFC 4180 style delimited text. Quoted fields may contain the delimiter, newlines, and
+ * doubled quotes. Rows beyond `limit` are counted but not returned.
+ */
+export function parseDelimited(text: string, delimiter: string, limit = 1000) {
+  const rows: string[][] = []
+  let row: string[] = []
+  let field = ""
+  let quoted = false
+  let total = 0
+  const endRow = () => {
+    row.push(field)
+    field = ""
+    const blank = row.length === 1 && row[0] === ""
+    if (!blank) {
+      total++
+      if (rows.length < limit) rows.push(row)
+    }
+    row = []
+  }
+  for (let index = 0; index < text.length; index++) {
+    const char = text[index]!
+    if (quoted) {
+      if (char !== '"') {
+        field += char
+        continue
+      }
+      if (text[index + 1] === '"') {
+        field += '"'
+        index++
+        continue
+      }
+      quoted = false
+      continue
+    }
+    if (char === '"' && field === "") {
+      quoted = true
+      continue
+    }
+    if (char === delimiter) {
+      row.push(field)
+      field = ""
+      continue
+    }
+    if (char === "\r") continue
+    if (char === "\n") {
+      endRow()
+      continue
+    }
+    field += char
+  }
+  if (field !== "" || row.length > 0) endRow()
+  const columns = rows.reduce((max, current) => Math.max(max, current.length), 0)
+  return { rows, total, columns }
+}
+
+/** Build a blob URL from loaded content. Callers revoke it when the viewer unmounts. */
+export function blobUrlFromContent(content: FileContent) {
+  const type = content.mimeType ?? "application/octet-stream"
+  if (content.encoding !== "base64") return URL.createObjectURL(new Blob([content.content], { type }))
+  const raw = atob(content.content)
+  const bytes = Uint8Array.from(raw, (char) => char.charCodeAt(0))
+  return URL.createObjectURL(new Blob([bytes], { type }))
+}
+
+/**
+ * Resolve a relative link against a directory. A relative base yields a workspace-relative path and
+ * an absolute base an absolute one; undefined when the link climbs past the base's root.
+ */
+export function resolveArtifactPath(base: string, href: string) {
+  const target = href.replaceAll("\\", "/")
+  if (target.startsWith("/")) return undefined
+  const dir = base.replaceAll("\\", "/")
+  const segments = [...dir.split("/").filter(Boolean)]
+  for (const segment of target.split("/")) {
+    if (!segment || segment === ".") continue
+    if (segment !== "..") {
+      segments.push(segment)
+      continue
+    }
+    if (segments.length === 0) return undefined
+    segments.pop()
+  }
+  return `${dir.startsWith("/") ? "/" : ""}${segments.join("/")}`
+}
@@ -5,11 +5,12 @@ import { createSimpleContext } from "@opencode/ui/context"
 import { showToast } from "@/shell/notifications/toast"
 import { useParams } from "@solidjs/router"
 import { base64Encode } from "@opencode/util/encode"
-import { getFilename } from "@opencode/util/path"
+import { getDirectory, getFilename } from "@opencode/util/path"
 import { useWorkspaceLocation } from "@/workspaces/location"
 import { useLanguage } from "@/runtime/i18n/language"
 import { useLayout } from "@/shell/state/layout"
 import { createPathHelpers } from "./path"
+import { fileContentFromBytes } from "./artifact"
 import {
  approxBytes,
  evictContentLru,
@@ -185,14 +186,17 @@ export const { use: useFile, provider: FileProvider } = createSimpleContext({

      setLoading(file)

+      // Files outside the workspace are read from their own directory, like markdown images.
+      // The trailing separator from getDirectory keeps "/" and "C:/" valid, like readLocalImage.
+      const request = path.absolute(file)
+        ? { path: getFilename(file), location: { directory: getDirectory(file) } }
+        : { path: file, location: { directory } }
      const promise = serverSDK.api.file
-        .read({ path: file, location: { directory } })
+        .read(request)
        .then((data) => {
          if (scope() !== directory) return
-          const content = { type: "text" as const, content: new TextDecoder().decode(data) }
+          const content = fileContentFromBytes(file, data)
          setLoaded(file, content)
-
-          if (!content) return
          touchFileContent(file, approxBytes(content))
          evictContent(new Set([file]))
        })
@@ -281,6 +285,7 @@ export const { use: useFile, provider: FileProvider } = createSimpleContext({
    return {
      ready: () => view().ready(),
      normalize: path.normalize,
+      absolute: path.absolute,
      tab: path.tab,
      pathFromTab: path.pathFromTab,
      tree: {
@@ -21,6 +21,24 @@ describe("file path helpers", () => {
    expect(path.normalize("c:\\repo\\src\\app.ts")).toBe("src\\app.ts")
  })

+  test("keeps files outside the workspace absolute and round-trips them through tabs", () => {
+    const posix = createPathHelpers(() => "/repo")
+    expect(posix.normalize("/tmp/out/report.pdf")).toBe("/tmp/out/report.pdf")
+    expect(posix.absolute("/tmp/out/report.pdf")).toBe(true)
+    expect(posix.absolute("src/app.ts")).toBe(false)
+    expect(posix.tab("/tmp/out/report.pdf")).toBe("file:///tmp/out/report.pdf")
+    expect(posix.pathFromTab("file:///tmp/out/report.pdf")).toBe("/tmp/out/report.pdf")
+    expect(posix.normalize("/repository/x.ts")).toBe("/repository/x.ts")
+
+    const windows = createPathHelpers(() => "C:\\repo")
+    expect(windows.normalize("C:\\tmp\\font.ttf")).toBe("C:\\tmp\\font.ttf")
+    expect(windows.normalize("file:///C:/tmp/font.ttf")).toBe("C:/tmp/font.ttf")
+    expect(windows.absolute("C:/tmp/font.ttf")).toBe(true)
+    expect(windows.tab("C:/tmp/font.ttf")).toBe("file:///C:/tmp/font.ttf")
+    expect(windows.pathFromTab("file:///C:/tmp/font.ttf")).toBe("C:/tmp/font.ttf")
+    expect(windows.pathFromTab("file:///C:/repo/src/app.ts")).toBe("src/app.ts")
+  })
+
  test("normalizes Windows directory separators", () => {
    const path = createPathHelpers(() => "C:\\repo")
    expect(path.normalizeDir("frontend\\")).toBe("frontend")
@@ -105,7 +105,11 @@ export function createPathHelpers(scope: () => string) {
  const normalize = (input: string) => {
    const root = scope()

-    let path = unquoteGitPath(decodeFilePath(stripQueryAndHash(stripFileProtocol(input))))
+    // file:///C:/dir becomes /C:/dir once the protocol is gone; restore the drive form.
+    let path = unquoteGitPath(decodeFilePath(stripQueryAndHash(stripFileProtocol(input)))).replace(
+      /^[/\\]([A-Za-z]:)/,
+      "$1",
+    )

    // Separator-agnostic prefix stripping for Cygwin/native Windows compatibility
    // Only case-insensitive on Windows (drive letter or UNC paths)
@@ -116,20 +120,21 @@ export function createPathHelpers(scope: () => string) {
      canonPath.startsWith(canonRoot) &&
      (canonRoot.endsWith("/") || canonPath === canonRoot || canonPath[canonRoot.length] === "/")
    ) {
-      // Slice from original path to preserve native separators
-      path = path.slice(root.length)
+      // Slice from original path to preserve native separators, then drop the separator itself.
+      path = path.slice(root.length).replace(/^[/\\]/, "")
    }

    if (path.startsWith("./") || path.startsWith(".\\")) {
      path = path.slice(2)
    }

-    if (path.startsWith("/") || path.startsWith("\\")) {
-      path = path.slice(1)
-    }
+    // An absolute path that is not under the root stays absolute; it is a file outside the workspace.
    return path
  }

+  /** Whether a normalized path points outside the workspace root. */
+  const absolute = (path: string) => /^[A-Za-z]:[/\\]/.test(path) || path.startsWith("/") || path.startsWith("\\\\")
+
  const tab = (input: string) => {
    const path = normalize(input)
    return `file://${encodeFilePath(path)}`
@@ -149,6 +154,7 @@ export function createPathHelpers(scope: () => string) {

  return {
    normalize,
+    absolute,
    tab,
    pathFromTab,
    normalizeDir,
@@ -1,4 +1,5 @@
 import { readFileSync } from "node:fs"
+import { createRequire } from "node:module"
 import solidPlugin from "vite-plugin-solid"
 import tailwindcss from "@tailwindcss/vite"
 import { fileURLToPath } from "url"
@@ -17,6 +18,24 @@ if (tailwindGenerate && typeof tailwindHotUpdate === "function") {
  }
 }

+// The markdown worker imports these directly, so they are served unbundled to keep worker startup
+// stable. Vite applies `exclude` to every import inside a pre-bundle too, which would leave a bare
+// `import "marked"` in mermaid's chunk that the browser cannot resolve from this package.
+const workerDeps = ["@shikijs/stream", "marked", "marked-shiki", "remend"]
+
+/** @type {import("rolldown").Plugin} */
+const bundleNestedWorkerDeps = {
+  name: "opencode-desktop:bundle-nested-worker-deps",
+  resolveId(id, importer) {
+    if (!importer || !workerDeps.includes(id) || !importer.includes("node_modules")) return
+    try {
+      return createRequire(importer).resolve(id)
+    } catch {
+      return
+    }
+  },
+}
+
 export const channel = (() => {
  const raw = process.env.OPENCODE_CHANNEL
  if (raw === "local" || raw === "dev" || raw === "beta" || raw === "prod") return raw
@@ -44,8 +63,9 @@ export default [
          format: "es",
        },
        optimizeDeps: {
-          exclude: ["@shikijs/stream", "marked", "marked-shiki", "remend"],
+          exclude: workerDeps,
          include: ["@opencode/session-ui > mermaid", "@opencode/session-ui > mermaid > katex"],
+          rolldownOptions: { plugins: [bundleNestedWorkerDeps] },
        },
      }
    },
@@ -1,7 +1,7 @@
 {
  "$schema": "https://json.schemastore.org/package.json",
  "name": "@opencode/cli",
-  "version": "2.0.10",
+  "version": "2.0.12",
  "type": "module",
  "license": "MIT",
  "bin": {
@@ -55,7 +55,7 @@ try {
  if ((await pluginIDs(info.url, headers)).includes("smoke")) throw new Error("Smoke plugin existed before creation")
  const plugin = path.join(root, ".opencode", "plugins", "smoke.ts")
  await fs.writeFile(plugin, pluginSource())
-  await waitForPlugin(info.url, headers)
+  await waitForPlugin(info.url, headers, plugin)

  const unauthorizedInfo = await fetch(new URL("/api/info", info.url), {
    signal: AbortSignal.timeout(5_000),
@@ -139,7 +139,13 @@ async function waitForReady(url: string, headers: HeadersInit) {
 }

 function exitsWithin(process: Bun.Subprocess, milliseconds: number) {
-  return Promise.race([process.exited.then(() => true), Bun.sleep(milliseconds).then(() => false)])
+  return new Promise<boolean>((resolve) => {
+    const timeout = setTimeout(() => resolve(false), milliseconds)
+    process.exited.then(() => {
+      clearTimeout(timeout)
+      resolve(true)
+    })
+  })
 }

 function pluginSource() {
@@ -159,11 +165,15 @@ async function pluginIDs(url: string, headers: HeadersInit) {
  )
 }

-async function waitForPlugin(url: string, headers: HeadersInit) {
+async function waitForPlugin(url: string, headers: HeadersInit, plugin: string) {
  const deadline = Date.now() + 10_000
+  let attempt = 0
  while (Date.now() < deadline) {
    if ((await pluginIDs(url, headers)).includes("smoke")) return
    await Bun.sleep(25)
+    // Native watchers may coalesce a single creation edge. Keep changing valid source so
+    // the smoke proves that a later native event is delivered.
+    if (++attempt % 10 === 0) await fs.writeFile(plugin, `${pluginSource()}// watcher retry ${attempt}\n`)
  }
  throw new Error("Compiled service did not discover the created plugin")
 }
@@ -1,8 +1,9 @@
 import { OpenCode } from "@opencode/client"
 import { Service } from "@opencode/client/effect/service"
 import { Session } from "@opencode/schema/session"
+import { SessionMessage } from "@opencode/schema/session-message"
 import { SessionTransfer } from "@opencode/schema/session-transfer"
-import { Effect, Option, Schema } from "effect"
+import { Effect, Option, Predicate, Schema } from "effect"
 import { EOL } from "node:os"
 import path from "node:path"
 import { Commands } from "../../commands"
@@ -23,7 +24,13 @@ export default Runtime.handler(
      catch: (cause) =>
        new Error(`Failed to read session data: ${cause instanceof Error ? cause.message : String(cause)}`),
    })
-    const data = yield* Schema.decodeUnknownEffect(Schema.fromJsonString(SessionTransfer.Data))(text)
+    const raw = yield* Schema.decodeUnknownEffect(Schema.fromJsonString(Schema.Unknown))(text)
+    // Exports written before provider blobs were renamed to `native` still carry the old keys.
+    const data = yield* Schema.decodeUnknownEffect(SessionTransfer.Data)(
+      Predicate.isObject(raw) && Array.isArray(raw.messages)
+        ? { ...raw, messages: raw.messages.map(SessionMessage.persisted) }
+        : raw,
+    )
    const encoded = Schema.encodeSync(SessionTransfer.Data)(data)
    const server = yield* ServerConnection.resolve({
      server: Option.getOrUndefined(input.server),
@@ -5,34 +5,77 @@ import { Runtime } from "../../framework/runtime"
 import { Updater } from "../../services/updater"
 import { handlePromptErrors } from "../../ui/prompt"
 import { OPENCODE_VERSION } from "../../version"
+import { stripVTControlCharacters } from "node:util"

 export default Runtime.handler(
  Commands.commands.upgrade,
-  Effect.fn("cli.upgrade")(function* (input) {
-    intro("Upgrade")
-    const updater = yield* Updater.Service
-    const method = Option.getOrUndefined(input.method) ?? (yield* updater.method())
-    if (!method)
-      return yield* Effect.fail(
-        new Error("Could not detect the installation method. Pass --method to choose how to upgrade OpenCode."),
+  Effect.fn("cli.upgrade")(
+    function* (input) {
+      intro("Upgrade")
+      const updater = yield* Updater.Service
+      const method = Option.getOrUndefined(input.method) ?? (yield* updater.method())
+      if (!method)
+        return yield* Effect.fail(
+          new Error("Could not detect the installation method. Pass --method to choose how to upgrade OpenCode."),
+        )
+
+      log.info(`Using method: ${method}`)
+      const target = Option.getOrUndefined(input.target) ?? (yield* updater.latest())
+      const version = target.trim().replace(/^v/, "")
+      if (version === OPENCODE_VERSION) {
+        log.warn(`OpenCode upgrade skipped: ${version} is already installed`)
+        outro("Done")
+        return
+      }
+
+      log.info(`From ${OPENCODE_VERSION} → ${version}`)
+      const progress = spinner()
+      progress.start("Upgrading...")
+      yield* updater.upgrade(method, target).pipe(
+        Effect.tap(() => Effect.sync(() => progress.stop("Upgrade complete"))),
+        Effect.tapCause(() => Effect.sync(() => progress.stop("Upgrade failed", 1))),
      )
-
-    log.info(`Using method: ${method}`)
-    const target = Option.getOrUndefined(input.target) ?? (yield* updater.latest())
-    const version = target.trim().replace(/^v/, "")
-    if (version === OPENCODE_VERSION) {
-      log.warn(`OpenCode upgrade skipped: ${version} is already installed`)
      outro("Done")
-      return
-    }
-
-    log.info(`From ${OPENCODE_VERSION} → ${version}`)
-    const progress = spinner()
-    progress.start("Upgrading...")
-    yield* updater.upgrade(method, target).pipe(
-      Effect.tap(() => Effect.sync(() => progress.stop("Upgrade complete"))),
-      Effect.tapCause(() => Effect.sync(() => progress.stop("Upgrade failed", 1))),
-    )
-    outro("Done")
-  }, handlePromptErrors),
+    },
+    (effect) =>
+      handlePromptErrors(
+        effect.pipe(
+          Effect.mapError((error) =>
+            error instanceof Updater.UpgradeError ? new Error(formatUpgradeError(error), { cause: error }) : error,
+          ),
+        ),
+      ),
+  ),
 )
+
+function formatUpgradeError(error: Updater.UpgradeError) {
+  const clean = (value: string) => stripVTControlCharacters(value).replaceAll("\r", "").trim()
+  const line = (value: string) => clean(value).replace(/\s+/g, " ")
+  const detail = wrap(clean(error.detail), Math.max(24, (process.stdout.columns ?? 80) - 7)).join("\n")
+  return [
+    line(error.title),
+    "",
+    detail,
+    ...(error.command ? ["", field("Command", line(error.command))] : []),
+    field("Retry", line(error.retry)),
+  ].join("\n")
+}
+
+function field(label: string, value: string) {
+  const prefix = label.padEnd(9)
+  const width = Math.max(24, Math.min(61, (process.stdout.columns ?? 80) - prefix.length - 10))
+  const lines = wrap(value, width)
+  return lines.map((line, index) => `${index === 0 ? prefix : " ".repeat(prefix.length)}${line}`).join("\n")
+}
+
+function wrap(value: string, width: number) {
+  return value.split("\n").flatMap((source) => {
+    if (source.length <= width) return [source]
+    return source.split(/\s+/).reduce<string[]>((result, word) => {
+      const index = result.length - 1
+      if (index < 0 || result[index].length + word.length + 1 > width) result.push(word)
+      else result[index] += ` ${word}`
+      return result
+    }, [])
+  })
+}
@@ -7,7 +7,7 @@ import { produce, type Draft } from "immer"
 import { applyEdits, modify, parse, type ParseError } from "jsonc-parser"
 import path from "path"
 import { ConfigMigration } from "./migrate"
-import { Info, SchemaURL } from "./schema"
+import { Info, normalizeLegacyTabs, SchemaURL } from "./schema"

 export * from "./schema"

@@ -119,7 +119,7 @@ function merge(...values: readonly (Info | undefined)[]) {
  return Option.getOrElse(
    decode(
      values.reduce<Record<string, unknown>>(
-        (result, value) => mergeRecords(result, value ?? {}),
+        (result, value) => mergeRecords(result, normalizeLegacyTabs(value) ?? {}),
        {},
      ),
    ),
@@ -8,3 +8,11 @@ export const Info = Schema.Struct({
  ...Config.Info.fields,
 })
 export type Info = Schema.Schema.Type<typeof Info>
+
+export function normalizeLegacyTabs(info: Info | undefined) {
+  if (info?.tabs?.enabled === undefined) return info
+  const tabs = { ...info.tabs }
+  tabs.mode ??= tabs.enabled ? "on" : "off"
+  delete tabs.enabled
+  return { ...info, tabs }
+}
@@ -1,7 +1,8 @@
 #!/usr/bin/env bun

 import { NodeRuntime, NodeServices } from "@effect/platform-node"
-import { Effect } from "effect"
+import { Cause, Effect } from "effect"
+import { getErrorReported } from "effect/Runtime"
 import { Commands } from "./commands/commands"
 import { Runtime } from "./framework/runtime"
 import { Observability } from "@opencode/util/observability"
@@ -130,5 +131,15 @@ Effect.gen(function* () {
  Effect.provide(NodeServices.layer),
  Effect.scoped,
  Effect.tap(() => Effect.sync(() => process.exit(process.exitCode ?? 0))),
-  NodeRuntime.runMain,
+  // runMain's default reporter logs the fatal cause to stdout. Write it to stderr instead: the
+  // desktop and `Service.ensure` only capture stderr from `serve --service`, so this is the only
+  // channel through which a startup failure's reason reaches the user.
+  Effect.tapCause((cause) =>
+    Effect.sync(() => {
+      if (Cause.hasInterruptsOnly(cause)) return
+      if (!getErrorReported(Cause.squash(cause))) return
+      process.stderr.write(Cause.pretty(cause) + "\n")
+    }),
+  ),
+  NodeRuntime.runMain({ disableErrorReporting: true }),
 )
@@ -564,7 +564,7 @@ export async function runNonInteractivePrompt(input: Input) {
            messageID: message.id,
            type: "reasoning",
            text,
-            metadata: item.state,
+            metadata: item.native,
            time: { start: message.time.created, end: timestamp },
          }
          renderedReasoning.set(key, item.text)
@@ -5,7 +5,9 @@ import { Context, Duration, Effect, FileSystem, Layer, Option, Ref, Schema } fro
 import { ChildProcess } from "effect/unstable/process"
 import { parse, type ParseError } from "jsonc-parser"
 import path from "node:path"
+import { stripVTControlCharacters } from "node:util"
 import { action, parseReleaseVersion, type Policy } from "./updater-action"
+import { errorMessage } from "../util/error"

 export const methods = ["curl", "npm", "pnpm", "bun", "yarn", "vp", "brew"] as const

@@ -13,10 +15,82 @@ export type Method = (typeof methods)[number]
 export type RunResult = { readonly type: "available" | "installed"; readonly version: string }
 export type CheckResult = RunResult | { readonly type: "unavailable"; readonly message: string }

+export class UpgradeError extends Error {
+  readonly title: string
+  readonly detail: string
+  readonly command?: string
+  readonly retry: string
+
+  constructor(
+    input: {
+      readonly title: string
+      readonly detail: string
+      readonly command?: string
+      readonly retry: string
+    },
+    options?: ErrorOptions,
+  ) {
+    super(input.detail, options)
+    this.name = "UpgradeError"
+    this.title = input.title
+    this.detail = input.detail
+    this.command = input.command
+    this.retry = input.retry
+  }
+}
+
 const decodeVpPackages = Schema.decodeUnknownOption(
  Schema.fromJsonString(Schema.Array(Schema.Struct({ name: Schema.String }))),
 )

+const installNames: Record<Method, string> = {
+  curl: "The OpenCode installer",
+  npm: "npm",
+  pnpm: "pnpm",
+  bun: "Bun",
+  yarn: "Yarn",
+  vp: "Vite+",
+  brew: "Homebrew",
+}
+
+function conciseDetail(input: string) {
+  const lines = stripVTControlCharacters(input)
+    .trim()
+    .replaceAll("\r", "\n")
+    .split("\n")
+    .map((line) => line.trimEnd())
+    .filter((line) => line.trim().length > 0)
+  const tail = lines.slice(-12).join("\n")
+  const clipped = tail.length > 2_000
+  const detail = clipped ? `…${tail.slice(-1_999)}` : tail
+  if (!detail) return
+  if (lines.length <= 12 && !clipped) return detail
+  return `${detail}\n\nOutput shortened to the last 12 lines.`
+}
+
+function errorDetail(cause: unknown): string {
+  if (cause instanceof AppProcess.AppProcessError) {
+    const stderr = conciseDetail(cause.stderr ?? "")
+    if (stderr) return stderr
+    if (cause.cause !== undefined) return errorDetail(cause.cause)
+    return cause.message
+  }
+  if (cause instanceof Error) {
+    const detail = cause.cause === undefined ? undefined : errorDetail(cause.cause)
+    if (!detail || detail === cause.message) return cause.message
+    return `${cause.message}: ${detail}`
+  }
+  return errorMessage(cause)
+}
+
+function resultDetail(result: { code: number; stdout: string; stderr: string }) {
+  return (
+    conciseDetail(result.stderr) ??
+    conciseDetail(result.stdout) ??
+    `The command exited with code ${result.code} without any error output.`
+  )
+}
+
 export interface Interface {
  readonly run: (onInstall?: (version: string) => void) => Effect.Effect<RunResult | undefined>
  readonly check: () => Effect.Effect<CheckResult | undefined, Error>
@@ -24,9 +98,9 @@ export interface Interface {
  readonly method: () => Effect.Effect<Method | undefined>
  readonly latest: () => Effect.Effect<string, Error>
  readonly upgrade: (method: Method, version: string) => Effect.Effect<void, Error>
-  readonly removal: (method: Method) =>
-    | { readonly command: ReadonlyArray<string>; readonly run: Effect.Effect<void, Error> }
-    | undefined
+  readonly removal: (
+    method: Method,
+  ) => { readonly command: ReadonlyArray<string>; readonly run: Effect.Effect<void, Error> } | undefined
 }

 export class Service extends Context.Service<Service, Interface>()("@opencode/cli/Updater") {}
@@ -89,7 +163,6 @@ const make = Effect.gen(function* () {
          stdout: result.stdout.toString("utf8"),
          stderr: result.stderr.toString("utf8"),
        })),
-        Effect.orElseSucceed(() => ({ code: 1, stdout: "", stderr: "" })),
      )
  })

@@ -119,7 +192,11 @@ const make = Effect.gen(function* () {
    ]
    const results = yield* Effect.forEach(
      checks,
-      (check) => exec(check.command).pipe(Effect.map((result) => ({ check, result }))),
+      (check) =>
+        exec(check.command).pipe(
+          Effect.orElseSucceed(() => ({ code: 1, stdout: "", stderr: "" })),
+          Effect.map((result) => ({ check, result })),
+        ),
      { concurrency: "unbounded" },
    )
    return results.find((result) => {
@@ -144,11 +221,7 @@ const make = Effect.gen(function* () {
    return {
      command,
      run: exec(command, "5 minutes").pipe(
-        Effect.flatMap((result) =>
-          result.code === 0
-            ? Effect.void
-            : Effect.fail(new Error(result.stderr.trim() || `Failed to uninstall with ${method}`)),
-        ),
+        Effect.flatMap((result) => (result.code === 0 ? Effect.void : Effect.fail(new Error(resultDetail(result))))),
      ),
    }
  }
@@ -163,14 +236,44 @@ const make = Effect.gen(function* () {
            signal: AbortSignal.any([signal, AbortSignal.timeout(10_000)]),
          },
        ),
-      catch: (cause) => new Error("Failed to check for updates", { cause }),
+      catch: (cause) =>
+        new UpgradeError(
+          {
+            title: "Could not check for OpenCode updates",
+            detail: errorDetail(cause),
+            retry: "Check your network, then run opencode upgrade again.",
+          },
+          { cause },
+        ),
    })
-    if (!response.ok) return yield* Effect.fail(new Error(`Update check failed with status ${response.status}`))
+    if (!response.ok)
+      return yield* Effect.fail(
+        new UpgradeError({
+          title: "Could not check for OpenCode updates",
+          detail: `The update service returned HTTP ${response.status}.`,
+          retry: "Try again in a few minutes.",
+        }),
+      )
    const data: { version: string; metadata?: { package?: string } } = yield* Effect.tryPromise({
      try: () => response.json(),
-      catch: (cause) => new Error("Failed to read update information", { cause }),
+      catch: (cause) =>
+        new UpgradeError(
+          {
+            title: "Could not read the OpenCode update information",
+            detail: errorDetail(cause),
+            retry: "Try again in a few minutes.",
+          },
+          { cause },
+        ),
    })
-    if (!data.metadata?.package) return yield* Effect.fail(new Error("Update information did not include a package"))
+    if (!data.metadata?.package)
+      return yield* Effect.fail(
+        new UpgradeError({
+          title: "Could not read the OpenCode update information",
+          detail: "The update service returned incomplete release information.",
+          retry: "Try again in a few minutes.",
+        }),
+      )
    return { package: data.metadata.package, version: data.version }
  })

@@ -185,6 +288,40 @@ const make = Effect.gen(function* () {
      fs.remove(directory, { recursive: true, force: true }).pipe(Effect.ignore),
    )

+  const runUpgrade = (input: {
+    readonly method: Method
+    readonly command: string[]
+    readonly displayCommand?: string[]
+    readonly title?: string
+    readonly retry?: string
+  }) => {
+    const failure = (detail: string, cause?: unknown) =>
+      new UpgradeError(
+        {
+          title: input.title ?? `${installNames[input.method]} could not install OpenCode`,
+          detail,
+          command: (input.displayCommand ?? input.command).join(" "),
+          retry: input.retry ?? "Fix the issue above, then run opencode upgrade again.",
+        },
+        cause === undefined ? undefined : { cause },
+      )
+    return exec(input.command, "5 minutes").pipe(
+      Effect.flatMap((result) =>
+        result.code === 0 ? Effect.succeed(result) : Effect.fail(failure(resultDetail(result))),
+      ),
+      Effect.mapError((cause) =>
+        cause instanceof UpgradeError
+          ? cause
+          : failure(
+              cause instanceof AppProcess.AppProcessError && cause.stderr === undefined && cause.cause === undefined
+                ? `Failed to update with ${input.method}`
+                : errorDetail(cause),
+              cause,
+            ),
+      ),
+    )
+  }
+
  const upgrade = Effect.fnUntraced(function* (method: Method, input: string) {
    if (!parseReleaseVersion(input)) return yield* Effect.fail(new Error(`Invalid version: ${input}`))
    const version = input.trim().replace(/^v/, "")
@@ -212,31 +349,54 @@ const make = Effect.gen(function* () {
          ? ["vp", "install", "-g", "--force", target]
          : ["vp", "update", "-g", target],
    }
-    const result = yield* Effect.scoped(
+    yield* Effect.scoped(
      Effect.gen(function* () {
        if (method === "bun") {
          // Bun does not prune old versions from its shared package cache.
          yield* fs.makeDirectory(global.cache, { recursive: true })
          const cache = yield* temporaryDirectory("update-")
-          return yield* exec(["bun", "install", "--global", "--trust", "--cache-dir", cache, target], "5 minutes")
+          return yield* runUpgrade({
+            method,
+            command: ["bun", "install", "--global", "--trust", "--cache-dir", cache, target],
+            displayCommand: ["bun", "install", "--global", "--trust", target],
+          })
        }
        if (method === "curl") {
          yield* fs.makeDirectory(global.cache, { recursive: true })
          const directory = yield* temporaryDirectory("update-")
          const installer = path.join(directory, "install")
-          const download = yield* exec(
-            ["curl", "-fsSL", "-o", installer, "https://opencode.ai/v2/install"],
-            "5 minutes",
-          )
-          if (download.code !== 0) return download
-          return yield* exec(["bash", installer, "--version", version, "--no-modify-path"], "5 minutes")
+          yield* runUpgrade({
+            method,
+            command: ["curl", "-fsSL", "-o", installer, "https://opencode.ai/v2/install"],
+            displayCommand: ["curl", "-fsSL", "https://opencode.ai/v2/install"],
+            title: "Could not download the OpenCode installer",
+            retry: "Check your network, then run opencode upgrade again.",
+          })
+          return yield* runUpgrade({
+            method,
+            command: ["bash", installer, "--version", version, "--no-modify-path"],
+            displayCommand: ["opencode", "upgrade", version, "--method", "curl"],
+            title: "The OpenCode installer failed",
+          })
        }
-        if (method === "brew") return yield* exec(["brew", "upgrade", packageName], "5 minutes")
-        return yield* exec(commands[method], "5 minutes")
+        if (method === "brew") return yield* runUpgrade({ method, command: ["brew", "upgrade", packageName] })
+        return yield* runUpgrade({ method, command: commands[method] })
      }),
-    ).pipe(Effect.mapError((cause) => new Error(`Failed to update with ${method}`, { cause })))
-    if (result.code === 0) return
-    return yield* Effect.fail(new Error(result.stderr.trim() || `Failed to update with ${method}`))
+    ).pipe(
+      Effect.mapError((cause) =>
+        cause instanceof UpgradeError
+          ? cause
+          : new UpgradeError(
+              {
+                title: "Could not prepare the OpenCode upgrade",
+                detail: errorDetail(cause),
+                retry: "Fix the issue above, then run opencode upgrade again.",
+              },
+              { cause },
+            ),
+      ),
+      Effect.asVoid,
+    )
  })

  const inspect = Effect.fnUntraced(function* () {
@@ -78,7 +78,7 @@ test("merges inline CLI config content over the global config", async () => {
  await Bun.write(
    file,
    JSON.stringify({
-      tabs: { enabled: true, scope: "global" },
+      tabs: { mode: "on", scope: "global" },
      keybinds: { "app.exit": "ctrl+q" },
      plugins: ["global"],
      animations: true,
@@ -105,7 +105,7 @@ test("merges inline CLI config content over the global config", async () => {
      }),
    )

-    expect(result.loaded.tabs).toEqual({ enabled: false, scope: "global" })
+    expect(result.loaded.tabs).toEqual({ mode: "off", scope: "global" })
    expect(result.loaded.keybinds).toEqual({ "app.exit": "ctrl+q", "help.show": false })
    expect(result.loaded.plugins).toEqual(["inline"])
    expect(result.updated).toMatchObject({ animations: false, mouse: false })
@@ -116,6 +116,26 @@ test("merges inline CLI config content over the global config", async () => {
  }
 })

+test("reads the legacy tabs toggle without rewriting it", async () => {
+  await using directory = await tmpdir()
+  const file = path.join(directory.path, "cli.json")
+  await Bun.write(file, JSON.stringify({ tabs: { enabled: false } }))
+
+  const config = await run(
+    directory.path,
+    Effect.gen(function* () {
+      const service = yield* Config.Service
+      expect((yield* service.get()).tabs).toEqual({ mode: "off" })
+      return yield* service.update((draft) => {
+        draft.animations = false
+      })
+    }),
+  )
+
+  expect(config.tabs).toEqual({ mode: "off" })
+  expect(await Bun.file(file).json()).toEqual({ tabs: { enabled: false }, animations: false })
+})
+
 test("migrates tui and kv config into cli.json", async () => {
  await using directory = await tmpdir()
  await Bun.write(
@@ -1,7 +1,7 @@
 {
  "$schema": "https://json.schemastore.org/package.json",
  "name": "@opencode/client",
-  "version": "2.0.10",
+  "version": "2.0.12",
  "type": "module",
  "license": "MIT",
  "repository": {
@@ -509,12 +509,12 @@ export type PromptAgentAttachment = { name: string; mention?: PromptMention }

 export type PromptSkillAttachment = { id: string; name: string; text?: string; mention?: PromptMention }

-export type SessionMessageAssistantText = { type: "text"; text: string; state?: SessionMessageProviderState }
+export type SessionMessageAssistantText = { type: "text"; text: string; native?: SessionMessageProviderState }

 export type SessionMessageAssistantReasoning = {
  type: "reasoning"
  text: string
-  state?: SessionMessageProviderState
+  native?: SessionMessageProviderState
  time?: { created: number; completed?: number }
 }

@@ -1354,15 +1354,6 @@ export type SessionToolCalled = {
  }
 }

-export type SessionMessageAssistantText1 = { type: "text"; text: string; state?: SessionMessageProviderState1 }
-
-export type SessionMessageAssistantReasoning1 = {
-  type: "reasoning"
-  text: string
-  state?: SessionMessageProviderState1
-  time?: { created: number; completed?: number }
-}
-
 export type ToolContent1 = ToolTextContent | ToolFileContent1

 export type FormNumberField = {
@@ -1762,7 +1753,7 @@ export type SessionMessageCompactionCompleted = {
  status: "completed"
  reason: "auto" | "manual"
  model?: ModelRef
-  providerState?: SessionMessageProviderState
+  native?: SessionMessageProviderState
  summary: string
  recent: string
  providerContext?: SessionProviderContext
@@ -2228,7 +2219,7 @@ export type SessionMessageAssistant = {
  snapshot?: { start?: string; end?: string; files?: Array<string> }
  finish?: "stop" | "length" | "tool-calls" | "content-filter" | "error" | "unknown"
  rawFinish?: string
-  providerState?: SessionMessageProviderState
+  native?: SessionMessageProviderState
  cost?: MoneyUSD
  tokens?: TokenUsageInfo
  error?: SessionStructuredError
@@ -2236,8 +2227,13 @@ export type SessionMessageAssistant = {
 }

 export type SessionMessageAssistantContentEncoded =
-  | SessionMessageAssistantText1
-  | SessionMessageAssistantReasoning1
+  | { type: "text"; text: string; state?: SessionMessageProviderState1 }
+  | {
+      type: "reasoning"
+      text: string
+      time?: { created: number; completed?: number }
+      state?: SessionMessageProviderState1
+    }
  | SessionMessageAssistantTool1

 export type FormInfo = { id: string; sessionID: string; title: string; metadata?: FormMetadata; fields: FormFields }
@@ -3102,11 +3098,11 @@ export type SessionImportInput = {
          readonly agent: string
          readonly model: { readonly id: string; readonly providerID: string; readonly variant?: string }
          readonly content: ReadonlyArray<
-            | { readonly type: "text"; readonly text: string; readonly state?: { readonly [x: string]: JsonValue } }
+            | { readonly type: "text"; readonly text: string; readonly native?: { readonly [x: string]: JsonValue } }
            | {
                readonly type: "reasoning"
                readonly text: string
-                readonly state?: { readonly [x: string]: JsonValue }
+                readonly native?: { readonly [x: string]: JsonValue }
                readonly time?: { readonly created: number; readonly completed?: number }
              }
            | {
@@ -3180,7 +3176,7 @@ export type SessionImportInput = {
          readonly snapshot?: { readonly start?: string; readonly end?: string; readonly files?: ReadonlyArray<string> }
          readonly finish?: "stop" | "length" | "tool-calls" | "content-filter" | "error" | "unknown"
          readonly rawFinish?: string
-          readonly providerState?: { readonly [x: string]: JsonValue }
+          readonly native?: { readonly [x: string]: JsonValue }
          readonly cost?: number
          readonly tokens?: {
            readonly input: number
@@ -3214,7 +3210,7 @@ export type SessionImportInput = {
              readonly status: "completed"
              readonly reason: "auto" | "manual"
              readonly model?: { readonly id: string; readonly providerID: string; readonly variant?: string }
-              readonly providerState?: { readonly [x: string]: JsonValue }
+              readonly native?: { readonly [x: string]: JsonValue }
              readonly summary: string
              readonly recent: string
              readonly providerContext?: {
@@ -3419,11 +3415,11 @@ export type SessionImportInput = {
          readonly agent: string
          readonly model: { readonly id: string; readonly providerID: string; readonly variant?: string }
          readonly content: ReadonlyArray<
-            | { readonly type: "text"; readonly text: string; readonly state?: { readonly [x: string]: JsonValue } }
+            | { readonly type: "text"; readonly text: string; readonly native?: { readonly [x: string]: JsonValue } }
            | {
                readonly type: "reasoning"
                readonly text: string
-                readonly state?: { readonly [x: string]: JsonValue }
+                readonly native?: { readonly [x: string]: JsonValue }
                readonly time?: { readonly created: number; readonly completed?: number }
              }
            | {
@@ -3497,7 +3493,7 @@ export type SessionImportInput = {
          readonly snapshot?: { readonly start?: string; readonly end?: string; readonly files?: ReadonlyArray<string> }
          readonly finish?: "stop" | "length" | "tool-calls" | "content-filter" | "error" | "unknown"
          readonly rawFinish?: string
-          readonly providerState?: { readonly [x: string]: JsonValue }
+          readonly native?: { readonly [x: string]: JsonValue }
          readonly cost?: number
          readonly tokens?: {
            readonly input: number
@@ -3531,7 +3527,7 @@ export type SessionImportInput = {
              readonly status: "completed"
              readonly reason: "auto" | "manual"
              readonly model?: { readonly id: string; readonly providerID: string; readonly variant?: string }
-              readonly providerState?: { readonly [x: string]: JsonValue }
+              readonly native?: { readonly [x: string]: JsonValue }
              readonly summary: string
              readonly recent: string
              readonly providerContext?: {
@@ -3736,11 +3732,11 @@ export type SessionImportInput = {
          readonly agent: string
          readonly model: { readonly id: string; readonly providerID: string; readonly variant?: string }
          readonly content: ReadonlyArray<
-            | { readonly type: "text"; readonly text: string; readonly state?: { readonly [x: string]: JsonValue } }
+            | { readonly type: "text"; readonly text: string; readonly native?: { readonly [x: string]: JsonValue } }
            | {
                readonly type: "reasoning"
                readonly text: string
-                readonly state?: { readonly [x: string]: JsonValue }
+                readonly native?: { readonly [x: string]: JsonValue }
                readonly time?: { readonly created: number; readonly completed?: number }
              }
            | {
@@ -3814,7 +3810,7 @@ export type SessionImportInput = {
          readonly snapshot?: { readonly start?: string; readonly end?: string; readonly files?: ReadonlyArray<string> }
          readonly finish?: "stop" | "length" | "tool-calls" | "content-filter" | "error" | "unknown"
          readonly rawFinish?: string
-          readonly providerState?: { readonly [x: string]: JsonValue }
+          readonly native?: { readonly [x: string]: JsonValue }
          readonly cost?: number
          readonly tokens?: {
            readonly input: number
@@ -3848,7 +3844,7 @@ export type SessionImportInput = {
              readonly status: "completed"
              readonly reason: "auto" | "manual"
              readonly model?: { readonly id: string; readonly providerID: string; readonly variant?: string }
-              readonly providerState?: { readonly [x: string]: JsonValue }
+              readonly native?: { readonly [x: string]: JsonValue }
              readonly summary: string
              readonly recent: string
              readonly providerContext?: {
@@ -846,7 +846,7 @@ export function createData(config: CreateDataInput) {
            existing.error = undefined
            existing.finish = undefined
            existing.rawFinish = undefined
-            existing.providerState = undefined
+            existing.native = undefined
            existing.time.created = event.data.started
            existing.time.streamed = undefined
            existing.time.completed = undefined
@@ -880,7 +880,7 @@ export function createData(config: CreateDataInput) {
          assistant.time.completed = event.created
          assistant.finish = event.data.finish
          assistant.rawFinish = event.data.rawFinish
-          assistant.providerState = event.data.providerState
+          assistant.native = event.data.providerState
          assistant.cost = event.data.cost
          assistant.tokens = event.data.tokens
          if (event.data.snapshot) assistant.snapshot = { ...assistant.snapshot, end: event.data.snapshot }
@@ -892,7 +892,7 @@ export function createData(config: CreateDataInput) {
          assistant.time.completed = event.created
          assistant.finish = event.data.finish ?? "error"
          assistant.rawFinish = event.data.rawFinish
-          assistant.providerState = event.data.providerState
+          assistant.native = event.data.providerState
          assistant.error = event.data.error
          assistant.retry = undefined
          if (event.data.cost !== undefined && event.data.tokens !== undefined) {
@@ -914,6 +914,7 @@ export function createData(config: CreateDataInput) {
      case "session.text.ended":
        message.editText(event.data.sessionID, event.data.assistantMessageID, (text) => {
          text.text = event.data.text
+          text.native = event.data.state
        })
        return
      case "session.tool.input.started":
@@ -984,7 +985,7 @@ export function createData(config: CreateDataInput) {
          assistant.content.push({
            type: "reasoning",
            text: "",
-            state: event.data.state,
+            native: event.data.state,
            time: { created: event.created },
          })
        })
@@ -998,7 +999,7 @@ export function createData(config: CreateDataInput) {
        message.editReasoning(event.data.sessionID, event.data.assistantMessageID, (reasoning) => {
          reasoning.text = event.data.text
          reasoning.time = { created: reasoning.time?.created ?? event.created, completed: event.created }
-          if (event.data.state !== undefined) reasoning.state = event.data.state
+          if (event.data.state !== undefined) reasoning.native = event.data.state
        })
        return
      case "session.retry.scheduled":
@@ -1105,7 +1106,7 @@ export function createData(config: CreateDataInput) {
              status: "completed",
              reason: event.data.reason,
              model: event.data.model,
-              providerState: event.data.providerState,
+              native: event.data.providerState,
              providerContext: event.data.providerContext,
              summary: event.data.text,
              recent: event.data.recent,
@@ -1120,7 +1121,7 @@ export function createData(config: CreateDataInput) {
            status: "completed",
            reason: event.data.reason,
            model: event.data.model,
-            providerState: event.data.providerState,
+            native: event.data.providerState,
            providerContext: event.data.providerContext,
            summary: event.data.text,
            recent: event.data.recent,
@@ -135,7 +135,7 @@ test.each(["started", "cancelled", "failed"])(
          status: "completed",
          summary: "Summary",
          model,
-          providerState,
+          native: providerState,
          providerContext,
          cost: 0.01,
          tokens,
@@ -6,6 +6,8 @@
 - Tool schemas are the model-facing Interface. Keep arguments minimal and natural to the operation; never add unrelated IDs as ambient capability tokens.
 - State model-visible diagnostics, logs, tool descriptions, and instructions directly. The execution context is already clear; do not repeat `Code Mode` or `CodeMode` unless the distinction is necessary.
 - When interpreter behavior or support changes, update `interpreter-support.md` and direct tests in the same PR.
+- Program values are `Value` (`src/interpreter/objects.ts`); host values are `unknown` and are copied in at the boundaries (`fromHost`, `fromJson`). Do not widen program-facing signatures back to `unknown`.
+- A built-in kind of object is one `Obj` subclass (`Wrapper` for host-backed data such as Date or Map, `Opaque` for machinery such as functions and promises) that overrides `tag`, `toString`, `toPrimitive`, `inspect`, `toHost`, and `iterator` as needed. Do not add `instanceof` ladders over the built-in classes elsewhere; ask the object.

 ## OpenAPI

@@ -24,7 +24,7 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
      and Map, RegExp, and generators serialize as `{}`. A bare `undefined` result is `null`.
      Tool results come back the way `JSON.parse(JSON.stringify(result))` would. The table, where a value cannot
      be JSON but what the program meant is clear: a promise is awaited (a rejection fails the program), a Set
-      crosses as an array, a URLSearchParams as its query string, an Error as `{ name, message, ...own }`, a
+      crosses as an array, a URLSearchParams as its query string, an Error as `{ name, message, ...own enumerable }`, a
      Uint8Array is rejected with a hint to encode as text, and own `__proto__` keys are dropped so merging tool
      inputs or results cannot replace a prototype. In-program `JSON.stringify` keeps JS behavior except for the
      Error form and a promise, which is a `TypeError` with an await hint rather than a silent `{}`.
@@ -38,8 +38,11 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
      10,000,000 elements (`Array(n)`, `length =`, `Array.from`, `split`, `matchAll`, `concat`, `flat`; below the JS
      maximum of 2^32 - 1), and 10,000 pending promises at once. Exceeding one throws a `RangeError`. A single regular
      expression match can still run long on a pathological pattern; the host regex engine has no interrupt hook.
- [ ] Strict-mode early errors: duplicate parameter names, `yield` as an identifier, and a trailing comma after a
-      rest parameter are accepted unless the program itself begins with `"use strict"`.
+- [x] A trailing comma after a rest parameter is a syntax error, with or without `"use strict"`.
+- [x] A program that begins with `"use strict"` rejects `yield` as an identifier and duplicate parameter names at
+      parse time. Without it, `yield` is an ordinary binding.
+- [ ] Duplicate parameter names in non-strict code throw when the function is called, instead of binding the last
+      parameter as JavaScript does.

 ## Values and literals

@@ -84,7 +87,6 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] Destructuring reads through the prototype chain like member access: `const { constructor } = error` and
      `const { slice } = values` find the inherited built-in.
 - [ ] Member expressions as `for...in` targets (`for (x.y in obj)`).
- [ ] `IteratorClose` during destructuring should throw a `TypeError` when `return()` yields a non-object.

 ## Statements and control flow

@@ -94,7 +96,8 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] `for`, `while`, and `do...while`.
 - [x] `for...of` over arrays, strings, Maps, Sets, URLSearchParams, Headers, Uint8Arrays, built-in iterators, custom
      synchronous iterators, and confined synchronous generators. Abrupt completion invokes the iterator's optional `return()`.
- [x] `for...in` over own keys of plain objects, arrays, strings, and tool references; other values iterate nothing.
+- [x] `for...in` over own keys of plain objects, arrays, strings, and tool references. `null`, `undefined`, and other
+      non-objects iterate nothing. An un-awaited promise throws rather than iterating.
 - [x] Unlabeled `break` and `continue`.
 - [x] `try`, `catch`, optional catch bindings, and `finally`.
 - [x] `throw` with arbitrary values.
@@ -108,7 +111,8 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 ## Functions and callbacks

 - [x] Function declarations, function expressions, and arrow functions.
- [x] Synchronous and `async` functions.
+- [x] Synchronous and `async` functions. A line break between `function` and the name is allowed, as in JavaScript;
+      a line break between `async` and `function` is not an async function.
 - [x] Closures, recursion, default parameters, rest parameters, and destructured parameters.
 - [x] A call depth limit of 10000: deeper nesting throws a catchable `RangeError: Maximum call stack size exceeded`
      at the overflowing call instead of running until the timeout. Callbacks invoked by built-ins count below the
@@ -120,8 +124,8 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] `Boolean`, `Number`, `String`, `parseInt`, `parseFloat`, `isFinite`, `isNaN`, and URI helpers as callbacks.
 - [x] Built-in method references as callbacks, such as `values.map(Math.abs)`, `records.map(JSON.stringify)`,
      `items.forEach(console.log)`, and `Promise.resolve(-1).then(Math.abs)`. Extra callback arguments a built-in
-      does not consume are ignored, like JS; consumed arguments stay strictly validated (`Math.floor` still rejects a
-      string). A detached method loses its receiver, as in JS: `values.filter("abc".includes)` is a `TypeError`
+      does not consume are ignored, like JS, and consumed arguments coerce, like JS (`"3.7".replace(/\d\.\d/,
+    Math.floor)` is `"3"`). A detached method loses its receiver, as in JS: `values.filter("abc".includes)` is a `TypeError`
      because `includes` is called without a string `this`.
 - [x] Constructors work as callbacks with JS call semantics: `Error` types construct (`messages.map(Error)`),
      and new-requiring constructors (`Map`, `Set`, `URL`, `URLSearchParams`, `Headers`, `Promise`) throw a `TypeError`,
@@ -141,11 +145,13 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
      assignments, object literal keys, and destructuring or parameter defaults.
 - [x] Built-in functions are objects too, with `name` and `length` (`Math.max.length === 2`,
      `Array.prototype.push.name === "push"`).
- [ ] A named function expression's name is not bound inside its own body.
- [ ] Redeclaring a function in the same scope is rejected; in JavaScript the last declaration wins.
- [ ] A line terminator between `async function` and the function name.
- [ ] Generator and async generator functions evaluate parameter defaults and destructuring at the first `next()`
-      rather than at the call, so their errors are not thrown synchronously.
+- [x] A named function expression's name is bound read-only inside its own body; assigning to it throws a
+      `TypeError`, as in strict mode.
+- [x] Redeclaring a function in the same scope, or alongside a `var`, is allowed: the last declaration wins.
+- [x] Generator functions have their own `prototype` (inheriting the shared generator prototype), so
+      `g() instanceof g` holds. Plain functions have none, since they cannot construct.
+- [x] Generator and async generator functions bind parameters (defaults, destructuring) at the call and defer only the
+      body to the first `next()`, so a bad argument throws synchronously from the call site, as in JS.
 - [x] Synchronous and async generator declarations/expressions, `yield`, and `yield*`, including lazy bodies,
      `next(value)`, `return(value)`, `throw(value)`, exhaustion, promise adoption, async request ordering,
      `try`/`catch`/`finally`, and sync/async iterator symbols. Async `yield*` awaits values while adapting a sync
@@ -158,7 +164,8 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
      rejected by every synchronous consumer.
 - [x] Synchronous iterator acquisition and result validation follow `IteratorClose` boundaries: consumer errors and
      intentional early stops invoke `return()`, acquisition/`next()` failures do not, and an original consumer error
-      wins over a cleanup failure. Async iterator consumption remains limited to `for await...of` and async `yield*`.
+      wins over a cleanup failure. A generator's `return()` is an intentional stop, so a `return()` that throws or
+      yields a non-object surfaces from it as a `TypeError`. Async iterator consumption remains limited to `for await...of` and async `yield*`.
 - [x] Portable generator protocol coverage is adapted from pinned Test262 cases for suspended-start, suspended-yield,
      and completed states; sync and async `next`/`return`/`throw`; finally yields and completion overrides; rejected
      yielded promises; mixed async request queues; sync and async `yield*` forwarding; malformed methods/results;
@@ -180,7 +187,8 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
      on any other value throws a catchable `TypeError` naming the callee: other built-in functions such as `Number`
      say `new` is unsupported and point at the plain call, user-defined functions report the constructor gap below,
      and non-callable values are not constructors. Error constructors take the ES2022 options object, so
-      `new Error(message, { cause })` installs a non-enumerable `cause` when the option is present.
+      `new Error(message, { cause })` installs a non-enumerable `cause` when the option is present. `Error.isError`
+      is true for every Error value.
 - [x] Arithmetic operators: `+`, `-`, `*`, `/`, `%`, and `**`.
 - [x] Equality and ordering: `==`, `!=`, `===`, `!==`, `<`, `<=`, `>`, and `>=`.
 - [x] Bitwise operators: `&`, `|`, `^`, `~`, `<<`, `>>`, and `>>>`.
@@ -191,13 +199,14 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] Plain, arithmetic, bitwise, and logical assignment operators.
 - [x] Property deletion on plain data objects and arrays, including computed and optional forms; deleting an array index
      creates a hole without changing its length. Deleting a non-configurable property (`length`) or
-      assigning a read-only one (`Math.PI`, `fn.name`) throws a `TypeError`, as in strict mode.
+      assigning a read-only one (`Math.PI`, `fn.name`) throws a `TypeError`, as in strict mode. `delete` of a
+      non-reference (`delete 0`, `delete f()`) evaluates the operand and is `true`; `delete x` on a variable throws.
 - [ ] Operators, `switch` discriminants, template interpolation, and coercion helpers such as `String` and `isNaN`
      applied to functions and namespaces; JavaScript coerces them, the interpreter rejects non-data operands.
 - [ ] ToPrimitive on object operands: operators, `Error(message)`, `Date` arguments, and `parseInt` radix should call
      `valueOf`/`toString` in spec order and surface their throws.
- [ ] Property keys follow ToPropertyKey: `x[null]`, `x[true]`, and objects (via `toString`) become string keys; only
-      strings and numbers are accepted.
+- [x] Property keys follow ToPropertyKey: `x[null]`, `x[true]`, and objects (via their built-in string form) become
+      string keys.

 ## Promises and tools

@@ -233,6 +242,10 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
      resolving with the promise itself rejects with a `TypeError`. Resolver callables work anywhere callbacks are
      accepted, including `.then`/`.catch` handlers and collection callbacks, and vanish at the data boundary like
      any function.
+- [x] `Promise.withResolvers()`: the same promise and resolver callables as the constructor, as a `{ promise, resolve,
+reject }` object.
+- [x] `Promise.try(fn, ...args)`: calls `fn` synchronously; a throw rejects, a return fulfils, and a returned promise or
+      thenable is adopted.
 - [x] Recursive assimilation of objects with an own callable `then` field across `Promise.resolve`, combinators,
      constructors, reactions, `finally`, `await`, and async returns. Thenable methods run deferred, receive
      first-call-wins resolve/reject functions, and ignore throws after settlement. Inherited/accessor `then` fields
@@ -253,7 +266,9 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
      not construct.
 - [x] `Object()` and `new Object()` return `{}` for nullish arguments and pass objects through unchanged;
      primitive wrapper objects (`Object(1)`) are rejected explicitly.
- [x] Computed property names and object spread.
+- [x] Computed property names and object spread. Any value works as a key (ToPropertyKey): strings, numbers, and the
+      two confined symbols as themselves, everything else as its string form (`o[null]` is `o["null"]`, `o[{}]` is
+      `o["[object Object]"]`), in reads, writes, literals, `in`, and destructuring.
 - [x] `Object.keys`, `Object.values`, `Object.entries`, `Object.hasOwn`, `Object.assign`, and `Object.fromEntries`, with
      synchronous iterator support for `fromEntries`. Sources follow ToObject: strings enumerate by index, other
      primitives and wrappers contribute nothing, and `null`/`undefined` throw. `Object.assign` accepts array
@@ -270,8 +285,9 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] `Object.is` for supported data values.
 - [x] `Object.groupBy` over finite collections and custom synchronous iterators/generators, with string-key coercion
      and plain-object results.
- [x] `Object.prototype` methods on values: `toString` (`"[object Array]"`), `toLocaleString`, `valueOf`,
-      `hasOwnProperty`, `isPrototypeOf`, and `propertyIsEnumerable`.
+- [x] `Object.prototype` methods on values: `toString` (`"[object Array]"`, `"[object Map]"`, `"[object Promise]"`, and so
+      on for every built-in kind, as JS reports through `Symbol.toStringTag`), `toLocaleString` (calls the value's
+      `toString`, as in JS), `valueOf`, `hasOwnProperty`, `isPrototypeOf`, and `propertyIsEnumerable`.

 ## Arrays

@@ -285,12 +301,14 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
      `lastIndexOf`.
 - [x] Aggregation: `reduce` and `reduceRight`.
 - [x] Ordering: `sort`, `toSorted`, `reverse`, and `toReversed`.
- [x] Access/copying: `at`, `slice`, `concat`, `flat`, `with`, and `join`.
+- [x] Access/copying: `at`, `slice`, `concat`, `flat`, `with`, `join`, and `toLocaleString` (each element's
+      `toLocaleString`, holes and nullish elements as empty strings).
 - [x] Mutation: `push`, `pop`, `shift`, `unshift`, `splice`, `fill`, and `copyWithin`.
 - [x] `keys`, `values`, `entries`, and `[Symbol.iterator]` (the same function as `values`) return live iterator objects
      with `next()` and `[Symbol.iterator]`, as in JS. Iterator objects are opaque references: they print as
      `[opaque reference]`, serialize to `{}`, and cannot be passed to extensions. Every built-in collection iterator
-      shares one prototype, which is only observable through `getPrototypeOf`.
+      shares one prototype. JavaScript gives each collection its own; the difference is not observable here because
+      `Object.getPrototypeOf` is not exposed.
 - [x] `length`, numeric indexing, index assignment, spread, and `for...of`.
 - [x] The `thisArg` argument of `Array.from` is accepted and ignored, like JS arrows.
 - [x] `Array.prototype.toSpliced`.
@@ -301,14 +319,17 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] Assigning `length` to truncate or extend an array; invalid lengths throw `RangeError`.
 - [x] Non-index own properties on arrays (`arr.foo = 1`, `arr.constructor = null`). They are excluded from the JSON
      form, like `JSON.stringify`.
- [ ] Argument coercion for `indexOf`, `lastIndexOf`, `includes`, `fill`, `flat`, `copyWithin`, and the `join`
-      separator: JavaScript applies ToIntegerOrInfinity/ToString (including `valueOf`, strings, and `undefined`), the
-      interpreter requires numbers and strings; `includes()`/`indexOf()` with no argument should search for
-      `undefined`.
+- [x] Numeric arguments coerce as in JS (ToIntegerOrInfinity): `indexOf(x, "1")`, `slice("1", "3")`, `at(null)`,
+      `flat(1.9)`, `with(1.5, v)`, `Math.max("3", "2")`, `parseInt("11", "2")`, `(1.5).toFixed("2")`,
+      `String.fromCharCode("65")`, and the Uint8Array equivalents. `join(sep)` and `JSON.parse(text)` apply ToString
+      (`join(null)` is `"1null2"`, `JSON.parse(123)` is `123`). `Array.from({ length: "2" })` applies ToLength; a
+      promise source still throws with an `await` hint rather than JS's silent `[]`. A program object's own
+      `valueOf`/`toString` is not consulted yet (see ToPrimitive above).

 ## Strings

- [x] Case/normalization: `toLowerCase`, `toUpperCase`, `normalize`.
+- [x] Case/normalization: `toLowerCase`, `toUpperCase`, `normalize`, and the `toLocaleLowerCase`/`toLocaleUpperCase`
+      aliases, which ignore their locale argument and apply the default Unicode casing.
 - [x] Trimming: `trim`, `trimStart`, and `trimEnd`, plus the Annex B `trimLeft` and `trimRight` aliases.
 - [x] Searching/tests: `includes`, `startsWith`, `endsWith`, `indexOf`, `lastIndexOf`, and `search`.
 - [x] Slicing/access: `slice`, `substring`, Annex B `substr`, `at`, `charAt`, `charCodeAt`, and `codePointAt`.
@@ -332,7 +353,8 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] Coercion functions: `Number`, `parseInt`, and `parseFloat`.
 - [x] Number predicates/parsers: `Number.isInteger`, `Number.isFinite`, `Number.isNaN`, `Number.isSafeInteger`,
      `Number.parseInt`, and `Number.parseFloat`.
- [x] Number formatting: `toFixed`, `toPrecision`, `toExponential`, `toString`, and `valueOf`.
+- [x] Number formatting: `toFixed`, `toPrecision`, `toExponential`, `toString`, `valueOf`, and `toLocaleString`, which
+      always formats as `en-US` (`"1,234.5"`) so output does not depend on the host.
 - [x] Number constants: `MAX_SAFE_INTEGER`, `MIN_SAFE_INTEGER`, `MAX_VALUE`, `MIN_VALUE`, `EPSILON`, `NaN`,
      `POSITIVE_INFINITY`, and `NEGATIVE_INFINITY`.
 - [x] Math constants: `PI`, `E`, `LN2`, `LN10`, `LOG2E`, `LOG10E`, `SQRT2`, and `SQRT1_2`.
@@ -345,7 +367,8 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
      use their epoch time) and reject opaque runtime references as data errors.
 - [x] Unknown static members on global namespaces and on `Number`/`String`/the coercion functions read as `undefined`
      for feature detection. Calling any undefined value reports a native-style `TypeError` naming the callee, for
-      example `Math.sum is not a function.` Unknown `Promise` statics keep their descriptive error.
+      example `Math.sum is not a function.` or `search(...).catch is not a function.` Unknown `Promise` statics keep
+      their descriptive error.
 - [x] `Math.sumPrecise` over finite collections and custom synchronous iterators/generators, rejecting non-number
      elements without coercion.
 - [x] Global coercing `isFinite` and `isNaN`; opaque runtime references reject as data errors, like `Number(...)`.
@@ -359,7 +382,8 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] `JSON.stringify` function and array replacers. Function replacers receive `(key, value)` in preorder, including
      the root, but no `this` holder. Array replacers preserve requested property order, deduplicate names, coerce
      number primitives, and ignore non-string/non-number entries. Primitive wrapper entries remain unsupported.
- [x] Captured `console.log`, `console.info`, `console.debug`, `console.warn`, and `console.error`.
+- [x] Captured `console.log`, `console.info`, `console.debug`, `console.warn`, and `console.error`. An Error prints as
+      `Error.prototype.toString` would show it (`Error: boom`), wherever it appears in the logged value.
 - [x] Captured `console.dir` and `console.table`.

 ## Date
@@ -379,6 +403,8 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
      `TimeClip` behavior.
 - [x] `Date.prototype.toUTCString` and its `toGMTString` alias.
 - [x] `toDateString` and `toTimeString` in the host's local timezone.
+- [x] `toLocaleString`, `toLocaleDateString`, and `toLocaleTimeString` always format as `en-US` in UTC
+      (`"1/1/1970, 12:00:00 AM"`) so output does not depend on the host.
 - [x] Native one-argument Date coercion for supported values, including booleans, null, arrays, and plain objects.
 - [ ] Date setters and multi-argument construction coerce object arguments through `valueOf`/`toString` and surface
      their throws.
@@ -400,15 +426,30 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] Match `indices` metadata for the `d` flag, including named groups on `exec`, `match`, and `matchAll` results.
 - [x] `RegExp.escape`.

+## Iterator
+
+- [x] `Iterator.prototype.map`, `filter`, `take`, `drop`, and `flatMap` on any iterator or generator: lazy, one source
+      step per result, closing the source when a callback throws, on early `return()`, or when `for...of` or
+      destructuring finishes with it early. Once done or closed a helper stays done, and a callback that re-enters its
+      own helper is a `TypeError`. `take`/`drop` coerce their count and reject `NaN` or negative counts with a
+      `RangeError`; `flatMap` callbacks must return an iterable or iterator, not a string.
+- [x] `Iterator.prototype.reduce`, `toArray`, `forEach`, `some`, `every`, and `find`, closing the source on early exit.
+- [x] `Iterator.from(value)` returns iterators and generators as they are, and wraps strings, iterables, and objects
+      with a `next` method. `Iterator` itself is abstract: calling or constructing it is a `TypeError`.
+- [x] Helpers and `Iterator.from` wrappers have `return()`; collection iterators (`array.values()`) do not, as in JS,
+      so an early exit from them leaves them where they were.
+- [ ] `Iterator.concat`, `Iterator.zip`, and `Iterator.zipKeyed` (stage 3 proposals).
+
 ## Map and Set

 - [x] Static `Map.groupBy` over finite collections and custom synchronous iterators/generators, preserving key identity.
 - [x] `new Map()` from synchronous iterables of entries.
- [x] Map `get`, `set`, `has`, `delete`, `clear`, `size`, and `forEach`.
+- [x] Map `get`, `set`, `has`, `delete`, `clear`, `size`, `forEach`, `getOrInsert`, and `getOrInsertComputed`.
+      `forEach` is live: entries deleted during the walk are skipped and entries added are visited, as in JS.
 - [x] `new Set()` from synchronous iterables.
 - [x] Set `add`, `has`, `delete`, `clear`, `size`, and `forEach`.
 - [x] Live `keys`, `values`, `entries`, and `[Symbol.iterator]` iterators for Map and Set; a Set-like operand's `keys()`
-      may return a built-in iterator or an array.
+      may return any iterator or an array.
 - [x] Spread, `for...of`, `Array.from`, and `Object.fromEntries` integration.
 - [x] Map and Set values serialize to `{}` at host/JSON boundaries.
 - [x] Set composition and relation methods: `union`, `intersection`, `difference`, `symmetricDifference`, `isSubsetOf`,
@@ -425,7 +466,8 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] `new URLSearchParams()` from query strings, data objects, synchronous iterables of pairs, and URLSearchParams.
 - [x] URLSearchParams `append`, `delete`, `get`, `getAll`, `has`, `set`, `sort`, `forEach`, `keys`, `values`,
      `entries`, `[Symbol.iterator]`, `toString`, and `size`.
- [x] URL values serialize to their href; URLSearchParams serialize to `{}`.
+- [x] URL values are their href in `JSON.stringify` and at the host boundary. URLSearchParams are `{}` in
+      `JSON.stringify` and their query string at the host boundary.

 ## Uint8Array

@@ -470,7 +512,8 @@ Nothing is exposed unless a host provides it; extension calls are not tool calls
 - [x] Every value crossing in either direction is converted, never shared: plain objects and arrays are copied,
      `Date`, `RegExp`, `URL`, `URLSearchParams`, `Headers`, `Map`, `Set`, and `Uint8Array` become fresh copies with
      their contents converted (a host `ArrayBuffer` comes in as a `Uint8Array`; other typed arrays cannot come out),
-      errors cross as errors with their name and message, and a `__proto__` key is dropped. Functions, generators,
+      errors cross as errors with their name, message, `cause`, and own enumerable data, and a `__proto__` key is
+      dropped. Functions, generators,
      un-awaited promises, and symbols cannot be passed in; a class instance, a symbol, or a BigInt cannot come out.
 - [x] A host function inside a result becomes a program function whose calls cross the same way, so a result can
      carry methods (`res.json()`) whose host closures keep the host state. Diagnostics name it by its path
@@ -495,8 +538,10 @@ Nothing is exposed unless a host provides it; extension calls are not tool calls
 - [x] `AggregateError` with the `(errors, message?)` signature and an own `errors` array, constructed directly or by
      an all-rejected `Promise.any`; direct construction accepts custom synchronous iterators and generators.
 - [x] Error `name`/`message`, error inheritance through `instanceof`, and plain-data serialization. `message` is an own
-      non-enumerable property and `name` is inherited, as in JS, so `Object.keys(err)` is `[]` while the host still
-      receives `{ name, message }`. Errors have no `stack`; the diagnostic carries the source location instead.
+      non-enumerable property and `name` is inherited, as in JS, so `Object.keys(err)` is `[]` for a plain error. The
+      result boundary still emits `{ name, message, ...own enumerable }`, so a field such as `code` crosses. `cause` is
+      non-enumerable: an extension Error carries it, and this JSON form does not. Errors have no `stack`; the diagnostic
+      carries a 1-based line and column in the submitted source instead.
 - [x] `instanceof` against any constructor with a `prototype`, including every built-in and `Function`.
 - [x] Catchable user throws, runtime failures raised during interpreted evaluation, awaited tool failures, and awaited
      tool-call-limit failures; parse/compile failures, cooperative timeout, and output bounding remain outside program
@@ -505,8 +550,9 @@ Nothing is exposed unless a host provides it; extension calls are not tool calls
      short orientation to the supported subset; this matrix is the full reference.
 - [x] Model-visible host failure messages and underlying causes, including output-validation errors.
 - [x] Caught errors do not distinguish user throws, interpreter failures, and tool failures; a program sees one
-      Error-shaped value with `name` and `message` in `catch`, rejection handlers, and `Promise.allSettled` reasons.
-      This is deliberate: the program should handle a failure the same way regardless of where it originated.
+      Error-shaped value in `catch`, rejection handlers, and `Promise.allSettled` reasons. It always has `name` and
+      `message`, plus `cause` and own data when the failure carried them. This is deliberate: the program should
+      handle a failure the same way regardless of where it originated.
 - [x] Failures raised by the interpreter are `TypeError`s unless JavaScript names them otherwise (`RangeError`,
      `ReferenceError`, `SyntaxError`, `URIError`), so `e instanceof TypeError` and `e.constructor === TypeError`
      hold. Unsupported syntax reached at runtime is a `SyntaxError`; awaited tool failures stay plain `Error`.
@@ -1,7 +1,7 @@
 {
  "$schema": "https://json.schemastore.org/package.json",
  "name": "@opencode/codemode",
-  "version": "2.0.10",
+  "version": "2.0.12",
  "description": "Effect-native confined code execution over schema-described tools",
  "type": "module",
  "license": "MIT",
@@ -15,6 +15,7 @@ import {
  Obj,
  PromiseObj,
  record,
+  type Value,
  SetObj,
  URLSearchParamsObj,
  HeadersObj,
@@ -23,14 +24,14 @@ import { typeofValue } from "./interpreter/references.js"

 export type Json = Schema.Json

-type Replacer<R> = (args: Array<unknown>) => Effect.Effect<unknown, unknown, R>
+type Replacer<R> = (args: Array<Value>) => Effect.Effect<Value, unknown, R>

 /**
 * What `JSON.stringify` would serialize for a program value, as host JSON: `toJSON` is honored, functions and
 * `undefined` vanish, non-finite numbers become null, and everything else is copied. Two departures from JS
 * so a mistake is not a silent `{}`: an Error serializes as `{ name, message, ...own }`, and a promise throws.
 */
-export const toJson = <R>(ctx: Interpreter<R>, value: unknown, replacer?: Replacer<R>) =>
+export const toJson = <R>(ctx: Interpreter<R>, value: Value, replacer?: Replacer<R>) =>
  walk(ctx, value, replacer, false)

 /**
@@ -38,11 +39,11 @@ export const toJson = <R>(ctx: Interpreter<R>, value: unknown, replacer?: Replac
 * awaited, a Set crosses as an array, a URLSearchParams as its query string, a Uint8Array asks to be encoded as
 * text first, and a `__proto__` key is dropped so host code can never receive one.
 */
-export const toBoundary = <R>(ctx: Interpreter<R>, value: unknown) => walk(ctx, value, undefined, true)
+export const toBoundary = <R>(ctx: Interpreter<R>, value: Value) => walk(ctx, value, undefined, true)

 const walk = <R>(
  ctx: Interpreter<R>,
-  value: unknown,
+  value: Value,
  replacer: Replacer<R> | undefined,
  boundary: boolean,
 ): Effect.Effect<Json | undefined, unknown, R> => {
@@ -104,7 +105,7 @@ const walk = <R>(
 }

 /** Host JSON as program values: objects and arrays are copied, primitives pass through. */
-export const fromJson = <R>(ctx: Interpreter<R>, value: unknown): unknown => {
+export const fromJson = <R>(ctx: Interpreter<R>, value: Json | undefined): Value => {
  if (value === null || typeof value !== "object") return value
  if (Array.isArray(value))
    return new Arr(
@@ -1,24 +1,35 @@
-import { Effect, Exit } from "effect"
-import { coerceToNumber, coerceToString } from "../stdlib/value.js"
+import { Cause, Effect, Exit } from "effect"
 import type { Interpreter } from "./interpreter.js"
-import { typeError } from "./model.js"
-import { Callable, get, Native, DateObj, Obj } from "./objects.js"
+import { primitivePrototype } from "./intrinsics.js"
+import { GeneratorReturn, typeError } from "./model.js"
+import {
+  Callable,
+  get,
+  Native,
+  DateObj,
+  Obj,
+  coerceToNumber,
+  coerceToString,
+  type Cursor,
+  type Value,
+} from "./objects.js"
 import { typeofValue } from "./references.js"

-export type IteratorCursor<R> = {
-  readonly next: Effect.Effect<{ readonly done: boolean; readonly value: unknown }, unknown, R>
-  readonly close: Effect.Effect<void, unknown, R>
-}
-
+/** IteratorClose: a consumer failure closes the iterator and wins over any close failure, except that a generator's
+ * return() is a return completion, so a failing close wins over it, as after `break`. */
 export const preserveConsumerError = <A, R>(
-  cursor: IteratorCursor<R>,
+  close: Cursor<R>["close"],
  effect: Effect.Effect<A, unknown, R>,
 ): Effect.Effect<A, unknown, R> =>
-  Effect.flatMap(Effect.exit(effect), (exit) =>
-    Exit.isSuccess(exit)
-      ? Effect.succeed(exit.value)
-      : Effect.andThen(Effect.exit(cursor.close), Effect.failCause(exit.cause)),
-  )
+  Effect.flatMap(Effect.exit(effect), (exit) => {
+    if (Exit.isSuccess(exit)) return Effect.succeed(exit.value)
+    return Effect.flatMap(Effect.exit(close), (closed) => {
+      if (!Exit.isSuccess(closed) && Cause.squash(exit.cause) instanceof GeneratorReturn) {
+        return Effect.failCause(closed.cause)
+      }
+      return Effect.failCause(exit.cause)
+    })
+  })

 /**
 * ToPrimitive: calls `valueOf`/`toString` in hint order and returns the first primitive result. Dates treat the
@@ -26,9 +37,9 @@ export const preserveConsumerError = <A, R>(
 */
 export const toPrimitive = <R>(
  ctx: Interpreter<R>,
-  value: unknown,
+  value: Value,
  hint: "number" | "string" | "default",
-): Effect.Effect<unknown, unknown, R> => {
+): Effect.Effect<Value, unknown, R> => {
  if (!(value instanceof Obj)) return Effect.succeed(value)
  const asString = hint === "string" || (hint === "default" && value instanceof DateObj)
  const order = asString ? ["toString", "valueOf"] : ["valueOf", "toString"]
@@ -43,24 +54,31 @@ export const toPrimitive = <R>(
  })
 }

-export const toPrimitiveString = <R>(ctx: Interpreter<R>, value: unknown) =>
+/** Invoke(value, name): calls the method the value would find through its prototype. */
+export const invoke = <R>(ctx: Interpreter<R>, value: Value, name: string, label: string) => {
+  const target = value instanceof Obj ? value : primitivePrototype(ctx.builtins, value)
+  if (target === undefined) throw typeError(`${label} called on null or undefined.`)
+  return ctx.call(get(target, name), value, [])
+}
+
+export const toPrimitiveString = <R>(ctx: Interpreter<R>, value: Value) =>
  Effect.map(toPrimitive(ctx, value, "string"), coerceToString)

-export const toPrimitiveNumber = <R>(ctx: Interpreter<R>, value: unknown) =>
+export const toPrimitiveNumber = <R>(ctx: Interpreter<R>, value: Value) =>
  Effect.map(toPrimitive(ctx, value, "number"), coerceToNumber)

 // The single acceptance list for callbacks: collections, sort, string replacers,
 // Array.from mappers, and promise reactions all admit exactly these callables.
 // Admission means dispatchable, not necessarily invocable: new-requiring
 // constructors pass the gate and throw a TypeError on call, like JS.
-export const isSupportedCallback = (value: unknown): value is Callable =>
+export const isSupportedCallback = (value: Value): value is Callable =>
  value instanceof Callable && !(value instanceof Native && !value.callback)

 export const applyCollectionCallback = <R>(
  ctx: Interpreter<R>,
-  callback: unknown,
+  callback: Value,
  name: string,
-): ((args: Array<unknown>) => Effect.Effect<unknown, unknown, R>) => {
+): ((args: Array<Value>) => Effect.Effect<Value, unknown, R>) => {
  if (!isSupportedCallback(callback)) {
    if (typeofValue(callback) === "function") {
      throw typeError(
@@ -6,10 +6,21 @@ import { type AstNode, formatLocation, PendingThrow, Throw, sourceLocation, type
 import { containsRuntimeReference } from "./references.js"
 import { createErrorValue, type ErrorType, isErrorType } from "./intrinsics.js"
 import { constructor, methods, prototypeFrom, receiver } from "./native.js"
-import { type Callable, define, get, has, hidden, type Native, Arr, ErrorObj, Obj } from "./objects.js"
+import {
+  type Callable,
+  define,
+  get,
+  has,
+  hidden,
+  type Native,
+  Arr,
+  ErrorObj,
+  Obj,
+  coerceToString,
+  type Value,
+} from "./objects.js"
 import type { Interpreter } from "./interpreter.js"
 import { formatValue } from "../stdlib/console.js"
-import { coerceToString } from "../stdlib/value.js"

 export const normalizeError = (error: unknown): Diagnostic => {
  if (error instanceof PendingThrow) {
@@ -86,7 +97,7 @@ export const locate = (error: unknown, node?: AstNode): unknown => {
 }

 /** The program value a handler receives for a failure; one failure always yields the same value. */
-export const materialize = <R>(ctx: Interpreter<R>, thrown: unknown): unknown => {
+export const materialize = <R>(ctx: Interpreter<R>, thrown: unknown): Value => {
  if (thrown instanceof Throw) return thrown.value
  const builtins = ctx.builtins
  if (thrown instanceof PendingThrow) {
@@ -113,7 +124,7 @@ const errorToString = (self: Obj): string => {

 export const createAggregateErrorValue = <R>(
  ctx: Interpreter<R>,
-  errors: Array<unknown>,
+  errors: Array<Value>,
  message: string,
  proto: Obj = ctx.builtins.AggregateError,
 ) => {
@@ -124,13 +135,13 @@ export const createAggregateErrorValue = <R>(

 const constructAggregateErrorValue = <R>(
  ctx: Interpreter<R>,
-  args: Array<unknown>,
+  args: Array<Value>,
  proto: Obj,
 ): Effect.Effect<ErrorObj, unknown, R> =>
  Effect.gen(function* () {
    const cursor = yield* ctx.iterate(args[0])
    if (cursor === undefined) throw typeError("new AggregateError(...) expects a synchronous iterable of errors.")
-    const errors: Array<unknown> = []
+    const errors: Array<Value> = []
    while (true) {
      const step = yield* cursor.next
      if (step.done) {
@@ -144,7 +155,7 @@ const constructAggregateErrorValue = <R>(
 export const errorGlobal = <R>(type: ErrorType, ctx: Interpreter<R>) => {
  const builtins = ctx.builtins
  const prototype = builtins[type]
-  const construct = (args: Array<unknown>, newTarget: Callable) => {
+  const construct = (args: Array<Value>, newTarget: Callable) => {
    const proto = prototypeFrom(newTarget, prototype)
    const created =
      type === "AggregateError"
@@ -168,6 +179,7 @@ export const errorGlobal = <R>(type: ErrorType, ctx: Interpreter<R>) => {
    methods(builtins, prototype, [
      ["toString", 0, (thisValue) => errorToString(receiver(Obj, thisValue, "Error.prototype.toString"))],
    ])
+    methods(builtins, ctor, [["isError", 1, (_, args) => args[0] instanceof ErrorObj]])
  }
  return ctor
 }
@@ -4,6 +4,7 @@ import type { DataValue, Diagnostic, ResolvedExecutionLimits, Result } from "../
 import { toBoundary } from "../data.js"
 import { ToolRuntime } from "../tool-runtime.js"
 import { normalizeError } from "./errors.js"
+import type { Value } from "./objects.js"
 import { createBuiltins } from "./intrinsics.js"
 import { Pending } from "./promises.js"
 import { Interpreter } from "./interpreter.js"
@@ -13,7 +14,7 @@ export const executeProgram = <R>(
  prepared: ToolRuntime.Prepared<R>,
  limits: ResolvedExecutionLimits,
  hooks: ToolRuntime.Hooks<R>,
-  globals?: (ctx: Interpreter<R>) => ReadonlyArray<readonly [string, unknown]>,
+  globals?: (ctx: Interpreter<R>) => ReadonlyArray<readonly [string, Value]>,
 ): Effect.Effect<Result, never, R> => {
  if (code.trim().length === 0) {
    return Effect.succeed({
@@ -1,6 +1,5 @@
 import { Effect } from "effect"
 import type { Extension } from "../extension.js"
-import { coerceToString } from "../stdlib/value.js"
 import { type ExtensionInvocation, hooked } from "../tool-runtime.js"
 import type { Interpreter } from "./interpreter.js"
 import { createErrorValue, isErrorType } from "./intrinsics.js"
@@ -8,9 +7,7 @@ import { MAX_VALUE_DEPTH } from "./limits.js"
 import { PendingThrow, Throw, typeError } from "./model.js"
 import { fn } from "./native.js"
 import {
-  Callable,
  define,
-  entries,
  get,
  has,
  hidden,
@@ -19,18 +16,17 @@ import {
  Bytes,
  DateObj,
  ErrorObj,
-  GeneratorObj,
-  IteratorObj,
+  HeadersObj,
  MapObj,
  Obj,
-  PromiseObj,
  RegExpObj,
  SetObj,
  URLObj,
  URLSearchParamsObj,
-  HeadersObj,
+  coerceToString,
+  type Value,
 } from "./objects.js"
-import { describeValue } from "./references.js"
+import { describeValue, isOpaque } from "./references.js"

 /**
 * The global bindings of one run's extensions. Everything crossing the boundary is converted: plain data and
@@ -40,35 +36,18 @@ import { describeValue } from "./references.js"
 export const extensionGlobals = <R>(
  ctx: Interpreter<R>,
  extensions: ReadonlyArray<Extension>,
-): ReadonlyArray<readonly [string, unknown]> => {
+): ReadonlyArray<readonly [string, Value]> => {
  const builtins = ctx.builtins

-  const toHost = (value: unknown, label: string, depth = 0, seen = new Set<object>()): unknown => {
+  const toHost = (value: Value, label: string, depth = 0, seen = new Set<object>()): unknown => {
    if (depth > MAX_VALUE_DEPTH) throw typeError(`${label} exceeds the maximum value depth of ${MAX_VALUE_DEPTH}.`)
-    if (value === null || typeof value !== "object") {
-      if (isPrimitive(value)) return value
-      throw typeError(`${label} contains ${describeValue(value)}, which cannot be passed to an extension.`)
-    }
-    if (value instanceof Bytes) return new Uint8Array(value.bytes)
-    if (value instanceof DateObj) return new Date(value.time)
-    if (value instanceof RegExpObj) return new RegExp(value.regex.source, value.regex.flags)
-    if (value instanceof URLObj) return new URL(value.url.href)
-    if (value instanceof URLSearchParamsObj) return new URLSearchParams(value.params)
-    if (value instanceof HeadersObj) return new Headers(value.headers)
-    const next = (item: unknown) => toHost(item, label, depth + 1, seen)
-    if (value instanceof MapObj) return new Map([...value.map].map(([key, item]) => [next(key), next(item)]))
-    if (value instanceof SetObj) return new Set([...value.set].map(next))
-    if (
-      !(value instanceof Obj) ||
-      value instanceof Callable ||
-      value instanceof GeneratorObj ||
-      value instanceof IteratorObj ||
-      value instanceof PromiseObj
-    ) {
+    if (isPrimitive(value)) return value
+    if (!(value instanceof Obj) || isOpaque(value)) {
      throw typeError(`${label} contains ${describeValue(value)}, which cannot be passed to an extension.`)
    }
    if (seen.has(value)) throw typeError(`${label} contains a circular value.`)
    seen.add(value)
+    const next = (item: Value) => toHost(item, label, depth + 1, seen)
    if (value instanceof ErrorObj) {
      const name = coerceToString(get(value, "name"))
      const message = get(value, "message")
@@ -89,19 +68,12 @@ export const extensionGlobals = <R>(
      seen.delete(value)
      return copied
    }
-    const copied =
-      value instanceof Arr
-        ? value.items.map(next)
-        : Object.fromEntries(
-            entries(value)
-              .filter(([key]) => key !== "__proto__")
-              .map(([key, item]) => [key, next(item)]),
-          )
+    const copied = value.toHost(next)
    seen.delete(value)
    return copied
  }

-  const fromHost = (value: unknown, label: string, depth = 0, seen = new Set<object>()): unknown => {
+  const fromHost = (value: unknown, label: string, depth = 0, seen = new Set<object>()): Value => {
    if (depth > MAX_VALUE_DEPTH) throw typeError(`${label} exceeds the maximum value depth of ${MAX_VALUE_DEPTH}.`)
    if (isPrimitive(value)) return value
    if (typeof value === "function") return wrap(value, label)
@@ -200,7 +172,7 @@ export const extensionGlobals = <R>(
 */
 const uncrossed = new Set(["stack", "constructor", "toString", "__proto__"])
 const left = Symbol("left behind")
-const crossing = (convert: () => unknown): unknown => {
+const crossing = <T>(convert: () => T): T | typeof left => {
  try {
    return convert()
  } catch (reason) {
@@ -219,7 +191,7 @@ const hostErrors = new Map<string, ErrorConstructor>([
 ])

 // The primitives the interpreter operates on; symbols and BigInts are not among them.
-const isPrimitive = (value: unknown): boolean =>
+const isPrimitive = (value: unknown): value is string | number | boolean | null | undefined =>
  value === null ||
  value === undefined ||
  typeof value === "string" ||
@@ -1,7 +1,7 @@
 import { Effect } from "effect"
 import { fn, type Method, methods, receiver } from "./native.js"
 import { AsyncIteratorSymbol, type GeneratorRequestKind, IteratorSymbol } from "./model.js"
-import { define, hidden, GeneratorObj } from "./objects.js"
+import { define, hidden, GeneratorObj, type Value } from "./objects.js"
 import type { Interpreter } from "./interpreter.js"

 /** `next`/`return`/`throw` on the generator prototypes; async generators answer with promises. */
@@ -13,9 +13,9 @@ export const generatorGlobals = <R>(ctx: Interpreter<R>): void => {
    const request = (kind: GeneratorRequestKind): Method => [
      kind,
      1,
-      (thisValue: unknown, args: Array<unknown>) => {
+      (thisValue: Value, args: Array<Value>) => {
        const generator = receiver(GeneratorObj, thisValue, `${label}.prototype.${kind}`)
-        const requested = generator.request(kind, args[0]) as Effect.Effect<unknown, unknown, R>
+        const requested = generator.request(kind, args[0]) as Effect.Effect<Value, unknown, R>
        return generator.asynchronous ? ctx.pending.create(requested) : requested
      },
    ]
@@ -1,4 +1,5 @@
 import { Effect } from "effect"
+import type { Value } from "./objects.js"
 import { arrayGlobal } from "../stdlib/array.js"
 import { textDecoderGlobal, textEncoderGlobal, uint8ArrayGlobal } from "../stdlib/bytes.js"
 import { mapGlobal, setGlobal } from "../stdlib/collections.js"
@@ -51,7 +52,7 @@ const symbolGlobal = <R>(ctx: Interpreter<R>) => {
  return symbol
 }

-type Factory = <R>(ctx: Interpreter<R>) => unknown
+type Factory = <R>(ctx: Interpreter<R>) => Value

 // A table rather than a list so the names are known before any runtime exists.
 const table: Record<string, Factory> = {
@@ -69,6 +70,7 @@ const table: Record<string, Factory> = {
  console: (ctx) => consoleGlobal(ctx),
  Promise: (ctx) => promiseGlobal(ctx),
  Symbol: (ctx) => symbolGlobal(ctx),
+  Iterator: (ctx) => iteratorGlobals(ctx),
  Number: (ctx) => numberGlobal(ctx),
  String: (ctx) => stringGlobal(ctx),
  Boolean: (ctx) => booleanGlobal(ctx),
@@ -100,8 +102,7 @@ const table: Record<string, Factory> = {
 export const globalNames: ReadonlySet<string> = new Set(Object.keys(table))

 /** The immutable global bindings of every program, in declaration order. */
-export const globals = <R>(ctx: Interpreter<R>): ReadonlyArray<readonly [string, unknown]> => {
+export const globals = <R>(ctx: Interpreter<R>): ReadonlyArray<readonly [string, Value]> => {
  generatorGlobals(ctx)
-  iteratorGlobals(ctx)
  return Object.entries(table).map(([name, factory]) => [name, factory(ctx)] as const)
 }
@@ -32,6 +32,7 @@ import type {
  Statement,
  Super,
  SwitchStatement,
+  Literal,
  TemplateLiteral,
  ThrowStatement,
  TryStatement,
@@ -62,33 +63,33 @@ import {
 } from "./model.js"
 import { checkStringLength } from "./limits.js"
 import { locate, materialize } from "./errors.js"
-import type { Builtins } from "./intrinsics.js"
+import { type Builtins, primitivePrototype } from "./intrinsics.js"
 import { globals } from "./globals.js"
 import {
  assign,
  Callable,
  define,
  get,
+  hostCursor,
+  IteratorObj,
+  type Cursor,
  has,
+  hidden,
  hasPrototype,
  keys,
  Native,
  parseArrayIndex,
  Arr,
-  Bytes,
-  DateObj,
  Fn,
  GeneratorObj,
-  IteratorObj,
-  MapObj,
  Obj,
  PromiseObj,
-  SetObj,
-  URLSearchParamsObj,
-  HeadersObj,
  record,
  remove,
  set,
+  coerceToNumber,
+  coerceToString,
+  type Value,
 } from "./objects.js"
 import { preserveConsumerError } from "./callback.js"
 import { Pending, resolvePromise, resolvePromiseValue } from "./promises.js"
@@ -96,7 +97,7 @@ import { containsOpaqueReference, describeValue, rejectCircularInsertion, typeof
 import { ScopeStack } from "./scope.js"
 import { constructRegExp } from "../stdlib/regexp.js"
 import { enumerableSource } from "../stdlib/object.js"
-import { coerceToNumber, coerceToString, compoundOperators } from "../stdlib/value.js"
+import { compoundOperators } from "../stdlib/value.js"

 // What a loop does with its body's result: exit with a StatementResult, or undefined to keep iterating.
 // Unlabelled break ends this loop; a label the loop does not carry propagates outward.
@@ -110,24 +111,36 @@ const loopExit = (result: StatementResult, labels: ReadonlySet<string> | undefin
  return undefined
 }

-const calleeDescription = (callee: Expression | Super | undefined): string => {
-  if (callee?.type === "Identifier") return callee.name
-  if (callee?.type === "MemberExpression") {
-    const object = callee.object
-    const property = callee.property
-    const key =
-      !callee.computed && property.type === "Identifier"
-        ? property.name
-        : property.type === "Literal" && typeof property.value === "string"
-          ? property.value
-          : undefined
-    if (object.type === "Identifier" && key !== undefined) return `${object.name}.${key}`
+// Native engines name the callee (`search(...).catch is not a function`), including call chains. Returns
+// undefined when a link cannot be named, so a chain is either named completely or not at all.
+const calleeDescription = (node: Expression | Super | undefined): string | undefined => {
+  if (node?.type === "Identifier") return node.name
+  if (node?.type === "CallExpression") {
+    const target = calleeDescription(node.callee)
+    return target === undefined ? undefined : `${target}(...)`
  }
-  return "The called value"
+  if (node?.type !== "MemberExpression") return undefined
+  const property = node.property
+  const key =
+    !node.computed && property.type === "Identifier"
+      ? property.name
+      : property.type === "Literal" && typeof property.value === "string"
+        ? property.value
+        : undefined
+  if (key === undefined) return undefined
+  const object = calleeDescription(node.object)
+  return object === undefined ? undefined : `${object}.${key}`
 }

 // OrdinaryHasInstance: walk the left operand's chain looking for the constructor's `prototype`.
-const instanceofValue = (lhs: unknown, rhs: unknown, node: AstNode): boolean => {
+// acorn types every literal as possibly a BigInt or RegExp; regex literals become RegExp objects before this is asked.
+const literal = (node: Literal): Value => {
+  if (typeof node.value === "bigint") throw typeError("BigInt literals are not supported.", node)
+  if (node.value instanceof RegExp) throw unsupportedSyntax("RegExpLiteral", node)
+  return node.value
+}
+
+const instanceofValue = (lhs: Value, rhs: Value, node: AstNode): boolean => {
  if (!(rhs instanceof Callable)) {
    throw typeError("The right-hand side of 'instanceof' is not callable.", node)
  }
@@ -224,7 +237,7 @@ const loopDeclaration = (left: VariableDeclaration | Pattern, statement: "for...

 type CustomIterator = {
  iterator: Obj
-  next: unknown
+  next: Value
  asynchronous: boolean
 }

@@ -232,13 +245,13 @@ type CustomIterator = {
 type MemberReference = {
  target: Obj
  key: PropertyKey
-  receiver: unknown
+  receiver: Value
 }

 type GeneratorRequest = {
  kind: GeneratorRequestKind
-  value: unknown
-  response: Deferred.Deferred<unknown, unknown>
+  value: Value
+  response: Deferred.Deferred<Value, unknown>
 }

 type GeneratorState = {
@@ -264,7 +277,7 @@ export class Interpreter<R> {
    readonly pending: Pending<R>
    readonly builtins: Builtins
    readonly logs?: Array<string>
-    readonly globals?: (ctx: Interpreter<R>) => ReadonlyArray<readonly [string, unknown]>
+    readonly globals?: (ctx: Interpreter<R>) => ReadonlyArray<readonly [string, Value]>
  }) {
    this.tools = options.tools
    this.pending = options.pending
@@ -278,27 +291,31 @@ export class Interpreter<R> {
    }
  }

-  run(program: Program): Effect.Effect<unknown, unknown, R> {
+  run(program: Program): Effect.Effect<Value, unknown, R> {
    return this.root.run(program)
  }

-  call(callable: unknown, thisValue: unknown, args: Array<unknown>): Effect.Effect<unknown, unknown, R> {
+  call(callable: Value, thisValue: Value, args: Array<Value>): Effect.Effect<Value, unknown, R> {
    return this.root.call(callable, thisValue, args)
  }

-  await(promise: PromiseObj): Effect.Effect<unknown, unknown, never> {
+  await(promise: PromiseObj): Effect.Effect<Value, unknown, never> {
    return this.root.await(promise)
  }

-  iterate(value: unknown) {
+  iterate(value: Value) {
    return this.root.iterate(value)
  }

+  iterateDirect(value: Value) {
+    return this.root.iterateDirect(value)
+  }
+
  /** Runs one host tool: arguments cross as JSON and the result comes back as program values. */
  tool(
    run: (args: Array<Json | undefined>) => Effect.Effect<Json | undefined, unknown, R>,
-    args: Array<unknown>,
-  ): Effect.Effect<unknown, unknown, R> {
+    args: Array<Value>,
+  ): Effect.Effect<Value, unknown, R> {
    const ctx = this
    return Effect.gen(function* () {
      const json = yield* Effect.forEach(args, (arg) => toBoundary(ctx, arg))
@@ -321,7 +338,7 @@ class Frame<R> {
    private depth = 0,
  ) {}

-  run(program: Program): Effect.Effect<unknown, unknown, R> {
+  run(program: Program): Effect.Effect<Value, unknown, R> {
    const self = this
    // Keep top-level declarations separate so they can shadow builtins.
    this.scopes.push()
@@ -329,7 +346,7 @@ class Frame<R> {
      self.predeclareLexical(program.body)
      self.hoistFunctions(program.body)
      self.hoistVars(program.body)
-      let value: unknown = undefined
+      let value: Value = undefined
      for (const [index, statement] of program.body.entries()) {
        if (index === program.body.length - 1 && statement.type === "ExpressionStatement") {
          value = yield* self.evaluateExpression(statement.expression)
@@ -354,15 +371,12 @@ class Frame<R> {
  }

  // Fork at the call site so admission and hooks occur when the call is made.
-  private createToolCallPromise(
-    path: ReadonlyArray<string>,
-    args: Array<unknown>,
-  ): Effect.Effect<PromiseObj, never, R> {
+  private createToolCallPromise(path: ReadonlyArray<string>, args: Array<Value>): Effect.Effect<PromiseObj, never, R> {
    return this.ctx.pending.create(this.ctx.tool((json) => this.ctx.tools.execute(path, json), args))
  }

  // Fiber exits make settlement idempotent; yielding prevents inline continuation.
-  await(promise: PromiseObj): Effect.Effect<unknown, unknown, never> {
+  await(promise: PromiseObj): Effect.Effect<Value, unknown, never> {
    const pending = this.ctx.pending
    return Effect.suspend(() => {
      pending.markObserved(promise)
@@ -441,8 +455,9 @@ class Frame<R> {
    node: FunctionDeclaration | FunctionExpression | ArrowFunctionExpression,
    name = node.type === "ArrowFunctionExpression" ? "" : (node.id?.name ?? ""),
  ): Fn {
-    return new Fn(
-      this.ctx.builtins.Function,
+    const builtins = this.ctx.builtins
+    const fn = new Fn(
+      builtins.Function,
      name,
      node.params,
      node.body,
@@ -450,20 +465,29 @@ class Frame<R> {
      node.async,
      node.generator,
    )
+    // Each generator function gets its own prototype, so `g() instanceof g` holds as in JS.
+    if (node.generator)
+      define(fn, "prototype", new Obj(node.async ? builtins.AsyncGenerator : builtins.Generator), hidden)
+    // The body of a named function expression sees its own name, read-only.
+    if (node.type === "FunctionExpression" && node.id) {
+      fn.capturedScopes.push(new Map([[node.id.name, { mutable: false, value: fn, initialized: true }]]))
+    }
+    return fn
  }

  // NamedEvaluation: an anonymous function definition takes the name of what it is assigned to.
-  private evaluateNamed(node: Expression, name: string): Effect.Effect<unknown, unknown, R> {
+  private evaluateNamed(node: Expression, name: string): Effect.Effect<Value, unknown, R> {
    if (node.type === "ArrowFunctionExpression" || (node.type === "FunctionExpression" && !node.id)) {
      return Effect.sync(() => this.createFunction(node, name))
    }
    return this.evaluateExpression(node)
  }

+  // Repeated `function` declarations and `var` clashes are legal: the last declaration wins.
  private hoistFunctions(statements: ReadonlyArray<Statement | ModuleDeclaration>): void {
    for (const node of statements) {
      if (node.type !== "FunctionDeclaration") continue
-      this.scopes.declare(node.id.name, this.createFunction(node), true, node)
+      this.scopes.current().set(node.id.name, { mutable: true, value: this.createFunction(node), initialized: true })
    }
  }

@@ -651,11 +675,11 @@ class Frame<R> {
      if (declared?.lexical) self.predeclarePattern(declared.pattern, declared.mutable, left)
      const right = yield* self.evaluateExpression(node.right)

-      const cursor = self.hostCursor(right)
+      const cursor = self.builtinCursor(right)
      const iterator = cursor === undefined ? yield* self.customIterator(right, node, awaiting) : undefined
      if (iterator === undefined && cursor === undefined) {
        throw invalidData(
-          `${awaiting ? "for await...of" : "for...of"} requires an array, string, Map, Set, URLSearchParams, or Headers, or custom iterator value.`,
+          `${awaiting ? "for await...of" : "for...of"} requires an iterable value, received ${describeValue(right)}.`,
          node,
        )
      }
@@ -671,7 +695,7 @@ class Frame<R> {
      }
      const assignment = left.type === "VariableDeclaration" ? undefined : left

-      const evaluateBody = (value: unknown) =>
+      const evaluateBody = (value: Value) =>
        Effect.gen(function* () {
          if (declared?.lexical) {
            self.scopes.push()
@@ -700,10 +724,8 @@ class Frame<R> {
        const bodyExit = yield* Effect.exit(evaluateBody(step.value))
        if (!Exit.isSuccess(bodyExit)) {
          // Process interruption must remain prompt; user cleanup cannot extend a timeout.
-          if (!Cause.hasInterruptsOnly(bodyExit.cause)) {
-            yield* Effect.exit(close())
-          }
-          return yield* Effect.failCause(bodyExit.cause)
+          if (Cause.hasInterruptsOnly(bodyExit.cause)) return yield* Effect.failCause(bodyExit.cause)
+          return yield* preserveConsumerError(close(), Effect.failCause(bodyExit.cause))
        }
        const exit = loopExit(bodyExit.value, labels)
        if (exit !== undefined) {
@@ -720,7 +742,7 @@ class Frame<R> {
    )
  }

-  private awaitValue(value: unknown): Effect.Effect<unknown, unknown, R> {
+  private awaitValue(value: Value): Effect.Effect<Value, unknown, R> {
    return Effect.flatMap(resolvePromise(this.ctx, value), (promise) =>
      Effect.ensuring(
        this.await(promise),
@@ -731,10 +753,10 @@ class Frame<R> {

  private awaitAsyncFromSyncValue(
    iterator: CustomIterator,
-    value: unknown,
+    value: Value,
    node: AstNode | undefined,
    closeOnRejection: boolean,
-  ): Effect.Effect<unknown, unknown, R> {
+  ): Effect.Effect<Value, unknown, R> {
    const self = this
    return Effect.gen(function* () {
      const settled = yield* Effect.exit(self.awaitValue(value))
@@ -746,54 +768,50 @@ class Frame<R> {
    })
  }

-  iterate(value: unknown, node?: AstNode) {
-    const cursor = this.hostCursor(value)
+  iterate(value: Value, node?: AstNode): Effect.Effect<Cursor<R> | undefined, unknown, R> {
+    const cursor = this.builtinCursor(value)
    if (cursor !== undefined) return Effect.succeed(cursor)
-    const self = this
    return Effect.map(this.customIterator(value, node, false), (iterator) =>
-      iterator === undefined
-        ? undefined
-        : {
-            next: self.nextIteratorResult(iterator, node, false),
-            close: Effect.suspend(() => self.closeIterator(iterator, node, false)),
-          },
+      iterator === undefined ? undefined : this.customCursor(iterator, node),
    )
  }

-  private hostCursor(value: unknown) {
-    const iterator =
-      value instanceof Arr
-        ? value.items[Symbol.iterator]()
-        : typeof value === "string"
-          ? value[Symbol.iterator]()
-          : value instanceof MapObj
-            ? value.map.entries()
-            : value instanceof SetObj
-              ? value.set.values()
-              : value instanceof URLSearchParamsObj
-                ? value.params.entries()
-                : value instanceof HeadersObj
-                  ? value.headers.entries()
-                  : value instanceof Bytes
-                    ? value.bytes.values()
-                    : value instanceof IteratorObj
-                      ? value.iterator
-                      : undefined
-    if (iterator === undefined) return undefined
-    const proto = this.ctx.builtins.Array
+  /** GetIteratorDirect: drive an iterator by its own `next`, without asking for `[Symbol.iterator]`. */
+  iterateDirect(value: Value, node?: AstNode): Cursor<R> {
+    if (value instanceof IteratorObj) return value.cursor as Cursor<R>
+    if (!(value instanceof Obj)) {
+      throw typeError(`An iterator must be an object, received ${describeValue(value)}.`, node)
+    }
+    return this.customCursor(
+      {
+        iterator: value,
+        next: this.requireIteratorMethod(get(value, "next"), "Iterator next", node),
+        asynchronous: false,
+      },
+      node,
+    )
+  }
+
+  private customCursor(iterator: CustomIterator, node: AstNode | undefined): Cursor<R> {
    return {
-      next: Effect.sync(() => {
-        const step = iterator.next()
-        return {
-          done: Boolean(step.done),
-          value: Array.isArray(step.value) ? new Arr(proto, step.value) : step.value,
-        }
-      }),
-      close: Effect.void,
+      next: this.nextIteratorResult(iterator, node, false),
+      close: Effect.suspend(() => this.closeIterator(iterator, node, false)),
    }
  }

-  private customIterator(value: unknown, node: AstNode | undefined, allowAsync = true) {
+  private builtinCursor(value: Value): Cursor<R> | undefined {
+    // Natives build their cursors without knowing R, like `lift` in native.ts.
+    if (value instanceof IteratorObj) return value.cursor as Cursor<R>
+    const iterator =
+      typeof value === "string"
+        ? value[Symbol.iterator]()
+        : value instanceof Obj
+          ? value.iterator(this.ctx.builtins)
+          : undefined
+    return iterator === undefined ? undefined : hostCursor(iterator)
+  }
+
+  private customIterator(value: Value, node: AstNode | undefined, allowAsync = true) {
    if (!(value instanceof Obj)) return Effect.undefined
    const asyncMethod = allowAsync ? get(value, AsyncIteratorSymbol) : undefined
    const method = asyncMethod ?? get(value, IteratorSymbol)
@@ -883,18 +901,18 @@ class Frame<R> {
    })
  }

-  private requireIteratorObject(value: unknown, context: string, node?: AstNode): Obj {
+  private requireIteratorObject(value: Value, context: string, node?: AstNode): Obj {
    if (value instanceof Obj) return value
    throw typeError(`${context} must be an object.`, node)
  }

-  private requireIteratorMethod(value: unknown, context: string, node?: AstNode): unknown {
+  private requireIteratorMethod(value: Value, context: string, node?: AstNode): Value {
    if (typeofValue(value) === "function") return value
    throw typeError(`${context} must be a function.`, node)
  }

  // for...in over null/undefined iterates nothing, like JS.
-  private enumerableKeys(value: unknown, node: AstNode): Array<string> {
+  private enumerableKeys(value: Value, node: AstNode): Array<string> {
    if (value instanceof ToolReference) return [...this.ctx.tools.keys(value.path)]
    if (value === null || value === undefined) return []
    return keys(enumerableSource(this.ctx, "for...in", value, node))
@@ -1058,7 +1076,7 @@ class Frame<R> {

  private declarePattern(
    pattern: Pattern,
-    value: unknown,
+    value: Value,
    mutable: boolean,
    node: AstNode,
    initialize = false,
@@ -1118,7 +1136,7 @@ class Frame<R> {
    })
  }

-  private assignPattern(pattern: Pattern, value: unknown, node: AstNode): Effect.Effect<void, unknown, R> {
+  private assignPattern(pattern: Pattern, value: Value, node: AstNode): Effect.Effect<void, unknown, R> {
    const self = this
    return Effect.gen(function* () {
      if (pattern.type === "Identifier") {
@@ -1170,7 +1188,7 @@ class Frame<R> {
    })
  }

-  private evaluateDefault(pattern: AssignmentPattern): Effect.Effect<unknown, unknown, R> {
+  private evaluateDefault(pattern: AssignmentPattern): Effect.Effect<Value, unknown, R> {
    return pattern.left.type === "Identifier"
      ? this.evaluateNamed(pattern.right, pattern.left.name)
      : this.evaluateExpression(pattern.right)
@@ -1178,8 +1196,8 @@ class Frame<R> {

  private destructureArrayPattern(
    pattern: ArrayPattern,
-    value: unknown,
-    consume: (target: Pattern, value: unknown, context: AstNode) => Effect.Effect<void, unknown, R>,
+    value: Value,
+    consume: (target: Pattern, value: Value, context: AstNode) => Effect.Effect<void, unknown, R>,
  ): Effect.Effect<void, unknown, R> {
    const self = this
    return Effect.gen(function* () {
@@ -1203,7 +1221,7 @@ class Frame<R> {
        done = step.done
        if (element === null) continue
        if (element.type === "RestElement") {
-          const rest: Array<unknown> = []
+          const rest: Array<Value> = []
          if (!step.done) rest.push(step.value)
          while (!done) {
            const next = yield* cursor.next
@@ -1214,7 +1232,7 @@ class Frame<R> {
          return
        }
        const consumed = consume(element, step.done ? undefined : step.value, pattern)
-        yield* step.done ? consumed : preserveConsumerError(cursor, consumed)
+        yield* step.done ? consumed : preserveConsumerError(cursor.close, consumed)
      }
      if (!done) yield* cursor.close
    })
@@ -1226,20 +1244,19 @@ class Frame<R> {
    }
    const keyNode = property.key
    if (property.computed) {
-      return Effect.map(this.evaluateExpression(keyNode), (value) => this.toPropertyKey(value, keyNode))
+      return Effect.map(this.evaluateExpression(keyNode), (value) => this.toPropertyKey(value))
    }
    if (keyNode.type === "Identifier") return Effect.succeed(keyNode.name)
    if (keyNode.type === "Literal") return Effect.succeed(String(keyNode.value))
    throw unsupportedSyntax(keyNode.type, keyNode)
  }

-  private evaluateExpression(node: Expression): Effect.Effect<unknown, unknown, R> {
+  private evaluateExpression(node: Expression): Effect.Effect<Value, unknown, R> {
    switch (node.type) {
      case "Literal": {
        const regex = node.regex
        if (regex) return Effect.sync(() => constructRegExp(this.ctx.builtins, [regex.pattern, regex.flags]))
-        if (typeof node.value === "bigint") throw typeError("BigInt literals are not supported.", node)
-        return Effect.succeed(node.value)
+        return Effect.succeed(literal(node))
      }
      case "Identifier":
        return Effect.sync(() => this.scopes.get(node.name, node))
@@ -1254,7 +1271,7 @@ class Frame<R> {
      case "SequenceExpression": {
        const self = this
        return Effect.gen(function* () {
-          let result: unknown
+          let result: Value
          for (const expression of node.expressions) {
            result = yield* self.evaluateExpression(expression)
          }
@@ -1295,7 +1312,7 @@ class Frame<R> {
    }
  }

-  private evaluateNewExpression(node: NewExpression): Effect.Effect<unknown, unknown, R> {
+  private evaluateNewExpression(node: NewExpression): Effect.Effect<Value, unknown, R> {
    const self = this
    return Effect.gen(function* () {
      const callee = yield* self.evaluateExpression(node.callee)
@@ -1305,7 +1322,7 @@ class Frame<R> {
        // `new` itself is supported, so a non-constructible callee is a TypeError like JS rather than
        // unsupported syntax. Built-ins like Number are real constructors in JS, so do not claim
        // otherwise; say `new` is unsupported for them and point at the plain call.
-        const name = calleeDescription(node.callee)
+        const name = calleeDescription(node.callee) ?? "The called value"
        const message =
          callee instanceof Fn
            ? `${name} cannot be constructed: user-defined constructors and classes are not supported. Call it as a function that returns a plain object instead.`
@@ -1319,7 +1336,7 @@ class Frame<R> {
    })
  }

-  private evaluateBinaryExpression(node: BinaryExpression): Effect.Effect<unknown, unknown, R> {
+  private evaluateBinaryExpression(node: BinaryExpression): Effect.Effect<Value, unknown, R> {
    const operator = node.operator
    const left = node.left
    if (left.type === "PrivateIdentifier") throw unsupportedSyntax(left.type, left)
@@ -1332,7 +1349,7 @@ class Frame<R> {
    })
  }

-  private applyBinaryOperator(operator: string, lhs: unknown, rhs: unknown, node: AstNode): unknown {
+  private applyBinaryOperator(operator: string, lhs: Value, rhs: Value, node: AstNode): Value {
    if (operator === "===") return lhs === rhs
    if (operator === "!==") return lhs !== rhs
    if (operator === "in" && rhs instanceof Obj && !containsOpaqueReference(lhs)) {
@@ -1341,14 +1358,9 @@ class Frame<R> {
    if (containsOpaqueReference(lhs) || containsOpaqueReference(rhs)) {
      throw invalidData("Binary operators require data values.", node)
    }
-    // Null-prototype data needs explicit primitive coercion; identity and `in` retain raw objects.
-    // Dates use their default string hint for addition and loose equality, and epoch time elsewhere.
-    const coerceOperand = (operand: unknown): unknown => {
-      if (operand instanceof DateObj) {
-        return operator === "+" || operator === "==" || operator === "!=" ? coerceToString(operand) : operand.time
-      }
-      return operand !== null && typeof operand === "object" ? coerceToString(operand) : operand
-    }
+    // Addition and loose equality use the default hint; every other operator asks for a number.
+    const hint = operator === "+" || operator === "==" || operator === "!=" ? "default" : "number"
+    const coerceOperand = (operand: Value) => (operand instanceof Obj ? operand.toPrimitive(hint) : operand)
    const bothObjects = lhs !== null && typeof lhs === "object" && rhs !== null && typeof rhs === "object"
    const l = coerceOperand(lhs)
    const r = coerceOperand(rhs)
@@ -1402,7 +1414,7 @@ class Frame<R> {
    }
  }

-  private evaluateLogicalExpression(node: LogicalExpression): Effect.Effect<unknown, unknown, R> {
+  private evaluateLogicalExpression(node: LogicalExpression): Effect.Effect<Value, unknown, R> {
    const operator = node.operator
    return Effect.flatMap(this.evaluateExpression(node.left), (left) => {
      if (operator === "&&") return left ? this.evaluateExpression(node.right) : Effect.succeed(left)
@@ -1413,7 +1425,7 @@ class Frame<R> {
    })
  }

-  private evaluateUnaryExpression(node: UnaryExpression): Effect.Effect<unknown, unknown, R> {
+  private evaluateUnaryExpression(node: UnaryExpression): Effect.Effect<Value, unknown, R> {
    const operator = node.operator
    const argument = node.argument
    if (operator === "delete") return this.evaluateDeleteExpression(argument)
@@ -1428,13 +1440,8 @@ class Frame<R> {
      if (containsOpaqueReference(value)) {
        throw invalidData("Unary operators require data values.", node)
      }
-      const operand =
-        value instanceof DateObj
-          ? value.time
-          : value !== null && typeof value === "object"
-            ? coerceToString(value)
-            : value
-      let result: unknown
+      const operand = value instanceof Obj ? value.toPrimitive("number") : value
+      let result: Value
      switch (operator) {
        case "+":
          result = +(operand as number)
@@ -1452,7 +1459,7 @@ class Frame<R> {
    })
  }

-  private evaluateAssignmentExpression(node: AssignmentExpression): Effect.Effect<unknown, unknown, R> {
+  private evaluateAssignmentExpression(node: AssignmentExpression): Effect.Effect<Value, unknown, R> {
    const left = node.left
    const operator = node.operator
    const self = this
@@ -1492,9 +1499,9 @@ class Frame<R> {
    node: AssignmentExpression,
    left: Pattern,
    operator: string,
-  ): Effect.Effect<unknown, unknown, R> {
+  ): Effect.Effect<Value, unknown, R> {
    const self = this
-    const shouldAssign = (current: unknown): boolean =>
+    const shouldAssign = (current: Value): boolean =>
      operator === "??=" ? current === null || current === undefined : operator === "||=" ? !current : Boolean(current)
    if (left.type === "Identifier") {
      const name = left.name
@@ -1519,7 +1526,7 @@ class Frame<R> {
    throw typeError("Assignment target must be an Identifier or MemberExpression.", left)
  }

-  private evaluateUpdateExpression(node: UpdateExpression): Effect.Effect<unknown, unknown, R> {
+  private evaluateUpdateExpression(node: UpdateExpression): Effect.Effect<Value, unknown, R> {
    const operator = node.operator
    const argument = node.argument
    const prefix = node.prefix
@@ -1532,7 +1539,7 @@ class Frame<R> {

    // CodeMode numeric coercion, not host Number(): null-prototype data objects would make
    // the host throw during ToPrimitive, and opaque runtime references must reject clearly.
-    const operand = (current: unknown): number => {
+    const operand = (current: Value): number => {
      if (containsOpaqueReference(current)) {
        throw invalidData(`'${operator}' requires a data value.`, argument)
      }
@@ -1561,7 +1568,7 @@ class Frame<R> {
  }

  // EvaluateCall: a member callee supplies its base object as `this`; anything else calls with undefined.
-  private evaluateCallExpression(node: CallExpression): Effect.Effect<unknown, unknown, R> {
+  private evaluateCallExpression(node: CallExpression): Effect.Effect<Value, unknown, R> {
    const callee = node.callee

    const self = this
@@ -1579,7 +1586,7 @@ class Frame<R> {
    })
  }

-  private readMethod(node: MemberExpression): Effect.Effect<{ callable: unknown; thisValue: unknown }, unknown, R> {
+  private readMethod(node: MemberExpression): Effect.Effect<{ callable: Value; thisValue: Value }, unknown, R> {
    return Effect.map(this.getMemberReference(node), (reference) => {
      if (reference === OptionalShortCircuit) return { callable: OptionalShortCircuit, thisValue: undefined }
      if (reference instanceof ToolReference) return { callable: reference, thisValue: undefined }
@@ -1590,12 +1597,12 @@ class Frame<R> {

  // The single dispatch for every invocation: call expressions and callbacks share it.
  call(
-    callable: unknown,
-    thisValue: unknown,
-    args: Array<unknown>,
+    callable: Value,
+    thisValue: Value,
+    args: Array<Value>,
    node?: AstNode,
    callee?: Expression,
-  ): Effect.Effect<unknown, unknown, R> {
+  ): Effect.Effect<Value, unknown, R> {
    const self = this
    return Effect.gen(function* () {
      if (callable instanceof ToolReference) {
@@ -1608,12 +1615,12 @@ class Frame<R> {
      if (callable instanceof Native) {
        return yield* self.native(() => (callable as Native<R>).call(thisValue, args), node)
      }
-      throw typeError(`${calleeDescription(callee)} is not a function.`, callee ?? node)
+      throw typeError(`${calleeDescription(callee) ?? "The called value"} is not a function.`, callee ?? node)
    })
  }

  // Built-ins throw without a location, synchronously or inside their Effect; the call site supplies it.
-  private native(body: () => Effect.Effect<unknown, unknown, R>, node?: AstNode): Effect.Effect<unknown, unknown, R> {
+  private native(body: () => Effect.Effect<Value, unknown, R>, node?: AstNode): Effect.Effect<Value, unknown, R> {
    return Effect.provideService(
      Effect.catchDefect(Effect.suspend(body), (defect) => Effect.die(locate(defect, node))),
      CallSite,
@@ -1623,10 +1630,10 @@ class Frame<R> {

  private evaluateCallArguments(
    argNodes: ReadonlyArray<Expression | SpreadElement>,
-  ): Effect.Effect<Array<unknown>, unknown, R> {
+  ): Effect.Effect<Array<Value>, unknown, R> {
    const self = this
    return Effect.gen(function* () {
-      const args: Array<unknown> = []
+      const args: Array<Value> = []
      for (const argNode of argNodes) {
        if (argNode.type === "SpreadElement") {
          const spread = yield* self.evaluateExpression(argNode.argument)
@@ -1646,20 +1653,20 @@ class Frame<R> {
  }

  // A callback invoked by a built-in runs below the call that invoked the built-in, so the deeper of the two counts.
-  invokeFunction(fn: Fn, args: Array<unknown>, node?: AstNode): Effect.Effect<unknown, unknown, R> {
+  invokeFunction(fn: Fn, args: Array<Value>, node?: AstNode): Effect.Effect<Value, unknown, R> {
    const self = this
    return Effect.flatMap(CallSite, (site) => {
      const depth = Math.max(self.depth, site.depth) + 1
      if (depth > MAX_CALL_DEPTH) throw rangeError("Maximum call stack size exceeded", node)
      const invocation = new Frame(this.ctx, new ScopeStack([...fn.capturedScopes, new Map()]), depth)
-      const run = Effect.gen(function* () {
-        // Seed all parameters first so defaults cannot fall through to same-named outer bindings.
-        const paramScope = invocation.scopes.current()
-        for (const parameter of fn.parameters) {
-          for (const name of collectPatternNames(parameter)) {
-            paramScope.set(name, { mutable: true, value: undefined, initialized: false })
-          }
+      // Seed all parameters first so defaults cannot fall through to same-named outer bindings.
+      const paramScope = invocation.scopes.current()
+      for (const parameter of fn.parameters) {
+        for (const name of collectPatternNames(parameter)) {
+          paramScope.set(name, { mutable: true, value: undefined, initialized: false })
        }
+      }
+      const bind = Effect.gen(function* () {
        for (const [index, parameter] of fn.parameters.entries()) {
          if (parameter.type === "RestElement") {
            yield* invocation.declarePattern(
@@ -1673,7 +1680,8 @@ class Frame<R> {
          }
          yield* invocation.declarePattern(parameter, args[index], true, parameter, true)
        }
-
+      })
+      const body = Effect.gen(function* () {
        if (fn.body.type === "BlockStatement") {
          invocation.scopes.push()
          invocation.hoistVars(fn.body.body, paramScope)
@@ -1683,7 +1691,9 @@ class Frame<R> {

        return yield* invocation.evaluateExpression(fn.body)
      })
-      if (fn.generator) return Effect.succeed(this.createGenerator(invocation, run, fn.async))
+      // Generators bind parameters at the call and defer only the body to the first `next()`, as in JS.
+      if (fn.generator) return Effect.map(bind, () => this.createGenerator(invocation, body, fn))
+      const run = Effect.andThen(bind, body)
      if (!fn.async) return run
      return this.ctx.pending.createWithSelf((self) =>
        Effect.flatMap(run, (value) => resolvePromiseValue(invocation.ctx, value, self)),
@@ -1691,18 +1701,15 @@ class Frame<R> {
    })
  }

-  private createGenerator(
-    invocation: Frame<R>,
-    run: Effect.Effect<unknown, unknown, R>,
-    asynchronous: boolean,
-  ): GeneratorObj {
+  private createGenerator(invocation: Frame<R>, run: Effect.Effect<Value, unknown, R>, fn: Fn): GeneratorObj {
+    const asynchronous = fn.async
    const state: GeneratorState = { started: false, completed: false, draining: false, pending: [], pendingIndex: 0 }
    invocation.generatorState = state
    invocation.generatorAsync = asynchronous
    const builtins = this.ctx.builtins
-    const result = (value: unknown, done: boolean) => record(builtins.Object, { value, done })
-    const request = (kind: GeneratorRequestKind, value: unknown) => {
-      const request = { kind, value, response: Deferred.makeUnsafe<unknown, unknown>() }
+    const result = (value: Value, done: boolean) => record(builtins.Object, { value, done })
+    const request = (kind: GeneratorRequestKind, value: Value) => {
+      const request = { kind, value, response: Deferred.makeUnsafe<Value, unknown>() }
      if (!asynchronous && state.active) return Effect.die(typeError("Generator is already running."))
      if (asynchronous && (state.completed || (!state.started && kind !== "next"))) {
        state.started = true
@@ -1763,17 +1770,13 @@ class Frame<R> {
      }
      return Deferred.await(request.response)
    }
-    const generator = new GeneratorObj(
-      asynchronous ? builtins.AsyncGenerator : builtins.Generator,
-      asynchronous,
-      request,
-    )
-    return generator
+    const proto = get(fn, "prototype")
+    return new GeneratorObj(proto instanceof Obj ? proto : builtins.Generator, asynchronous, request)
  }

  private completeGeneratorRequests(state: GeneratorState, asynchronous: boolean): Effect.Effect<void, never, R> {
    const self = this
-    const result = (value: unknown, done: boolean) => record(self.ctx.builtins.Object, { value, done })
+    const result = (value: Value, done: boolean) => record(self.ctx.builtins.Object, { value, done })
    return Effect.gen(function* () {
      while (true) {
        const pending = self.dequeueGeneratorRequest(state)
@@ -1819,7 +1822,7 @@ class Frame<R> {
    return request
  }

-  private evaluateYieldExpression(node: YieldExpression): Effect.Effect<unknown, unknown, R> {
+  private evaluateYieldExpression(node: YieldExpression): Effect.Effect<Value, unknown, R> {
    const argument = node.argument
    const self = this
    return Effect.gen(function* () {
@@ -1834,7 +1837,7 @@ class Frame<R> {
    })
  }

-  private suspendGenerator(value: unknown, node: AstNode): Effect.Effect<unknown, unknown, R> {
+  private suspendGenerator(value: Value, node: AstNode): Effect.Effect<Value, unknown, R> {
    const state = this.generatorState
    if (!state?.active) throw typeError("Generator has no active request.", node)
    Deferred.doneUnsafe(state.active.response, Exit.succeed(record(this.ctx.builtins.Object, { value, done: false })))
@@ -1849,20 +1852,11 @@ class Frame<R> {
    })
  }

-  private delegateYield(value: unknown, node: AstNode): Effect.Effect<unknown, unknown, R> {
+  private delegateYield(value: Value, node: AstNode): Effect.Effect<Value, unknown, R> {
    const self = this
    return Effect.gen(function* () {
-      if (
-        value instanceof Arr ||
-        typeof value === "string" ||
-        value instanceof MapObj ||
-        value instanceof SetObj ||
-        value instanceof URLSearchParamsObj ||
-        value instanceof HeadersObj ||
-        value instanceof Bytes
-      ) {
-        const cursor = yield* self.iterate(value, node)
-        if (!cursor) throw typeError("Built-in iterator is unavailable.", node)
+      const cursor = self.builtinCursor(value)
+      if (cursor !== undefined) {
        while (true) {
          const step = yield* cursor.next
          if (step.done) return undefined
@@ -1886,7 +1880,7 @@ class Frame<R> {
      const iterator = yield* self.customIterator(value, node, self.generatorAsync)
      if (!iterator) throw typeError("yield* requires a compatible iterable value.", node)
      let kind: GeneratorRequestKind = "next"
-      let input: unknown = undefined
+      let input: Value = undefined
      while (true) {
        const method = kind === "next" ? iterator.next : get(iterator.iterator, kind)
        if (method === undefined || method === null) {
@@ -1906,7 +1900,7 @@ class Frame<R> {
          node,
        )
        const done = Boolean(get(result, "done"))
-        const resultValue: unknown =
+        const resultValue: Value =
          self.generatorAsync && !iterator.asynchronous
            ? yield* self.awaitAsyncFromSyncValue(iterator, get(result, "value"), node, kind !== "return" && !done)
            : get(result, "value")
@@ -1915,7 +1909,7 @@ class Frame<R> {
          return resultValue
        }

-        const resumed: Exit.Exit<unknown, unknown> = yield* Effect.exit(self.suspendGenerator(resultValue, node))
+        const resumed: Exit.Exit<Value, unknown> = yield* Effect.exit(self.suspendGenerator(resultValue, node))
        if (Exit.isSuccess(resumed)) {
          kind = "next"
          input = resumed.value
@@ -1952,11 +1946,11 @@ class Frame<R> {
        let key: PropertyKey

        if (property.computed) {
-          key = self.toPropertyKey(yield* self.evaluateExpression(keyNode), keyNode)
+          key = self.toPropertyKey(yield* self.evaluateExpression(keyNode))
        } else if (keyNode.type === "Identifier") {
          key = keyNode.name
        } else if (keyNode.type === "Literal") {
-          key = self.toPropertyKey(keyNode.value, keyNode)
+          key = self.toPropertyKey(literal(keyNode))
        } else {
          throw typeError("Unsupported object property key shape.", keyNode)
        }
@@ -1975,7 +1969,7 @@ class Frame<R> {
  }

  private evaluateArrayExpression(node: ArrayExpression): Effect.Effect<Arr, unknown, R> {
-    const values: Array<unknown> = []
+    const values: Array<Value> = []

    const self = this
    return Effect.gen(function* () {
@@ -2030,13 +2024,13 @@ class Frame<R> {
    })
  }

-  private evaluateConditionalExpression(node: ConditionalExpression): Effect.Effect<unknown, unknown, R> {
+  private evaluateConditionalExpression(node: ConditionalExpression): Effect.Effect<Value, unknown, R> {
    return Effect.flatMap(this.evaluateExpression(node.test), (test) =>
      this.evaluateExpression(test ? node.consequent : node.alternate),
    )
  }

-  private applyCompoundAssignment(operator: string, current: unknown, incoming: unknown, node: AstNode): unknown {
+  private applyCompoundAssignment(operator: string, current: Value, incoming: Value, node: AstNode): Value {
    if (!compoundOperators.has(operator)) {
      throw typeError(`Unsupported assignment operator '${operator}'.`, node)
    }
@@ -2045,7 +2039,7 @@ class Frame<R> {

  private getMemberReference(
    node: MemberExpression,
-  ): Effect.Effect<MemberReference | ToolReference | { value: unknown } | typeof OptionalShortCircuit, unknown, R> {
+  ): Effect.Effect<MemberReference | ToolReference | { value: Value } | typeof OptionalShortCircuit, unknown, R> {
    const objectNode = node.object
    const propertyNode = node.property
    if (objectNode.type === "Super") throw unsupportedSyntax(objectNode.type, objectNode)
@@ -2057,10 +2051,10 @@ class Frame<R> {
      if ((objectValue === null || objectValue === undefined) && node.optional) return OptionalShortCircuit

      const key = node.computed
-        ? self.toPropertyKey(yield* self.evaluateExpression(propertyNode), propertyNode)
+        ? self.toPropertyKey(yield* self.evaluateExpression(propertyNode))
        : propertyNode.type === "Identifier"
          ? propertyNode.name
-          : self.toPropertyKey(yield* self.evaluateExpression(propertyNode), propertyNode)
+          : self.toPropertyKey(yield* self.evaluateExpression(propertyNode))

      if (objectValue instanceof ToolReference) {
        if (typeof key !== "string") {
@@ -2071,16 +2065,14 @@ class Frame<R> {

      if (objectValue instanceof Obj) return { target: objectValue, key, receiver: objectValue }

-      // Primitives read through their wrapper prototype without being boxed; strings own length and indexes.
-      const builtins = self.ctx.builtins
+      // Strings own length and indexes; every other primitive property reads through the wrapper prototype.
      if (typeof objectValue === "string") {
        if (key === "length") return { value: objectValue.length }
        const index = typeof key === "symbol" ? undefined : parseArrayIndex(key)
        if (index !== undefined) return { value: objectValue[index] }
-        return { target: builtins.String, key, receiver: objectValue }
      }
-      if (typeof objectValue === "number") return { target: builtins.Number, key, receiver: objectValue }
-      if (typeof objectValue === "boolean") return { target: builtins.Boolean, key, receiver: objectValue }
+      const proto = primitivePrototype(self.ctx.builtins, objectValue)
+      if (proto !== undefined) return { target: proto, key, receiver: objectValue }

      if (objectValue === null || objectValue === undefined) {
        throw typeError(`Cannot read properties of ${objectValue} (reading '${String(key)}').`, objectNode)
@@ -2089,7 +2081,7 @@ class Frame<R> {
    })
  }

-  private readReference(reference: MemberReference, node: MemberExpression): unknown {
+  private readReference(reference: MemberReference, node: MemberExpression): Value {
    // Reject unknown promise properties so a missing await cannot hide.
    if (reference.target instanceof PromiseObj && !has(reference.target, reference.key)) {
      throw invalidData(
@@ -2101,7 +2093,7 @@ class Frame<R> {
  }

  // Accessors throw without a location; the member or pattern that read them supplies it.
-  private readProperty(target: Obj, key: PropertyKey, node: AstNode, receiver: unknown = target): unknown {
+  private readProperty(target: Obj, key: PropertyKey, node: AstNode, receiver: Value = target): Value {
    try {
      return get(target, key, receiver)
    } catch (error) {
@@ -2109,7 +2101,7 @@ class Frame<R> {
    }
  }

-  private readMember(node: MemberExpression): Effect.Effect<unknown, unknown, R> {
+  private readMember(node: MemberExpression): Effect.Effect<Value, unknown, R> {
    return Effect.map(this.getMemberReference(node), (reference) => {
      if (reference === OptionalShortCircuit) return OptionalShortCircuit
      if (reference instanceof ToolReference) return reference
@@ -2118,15 +2110,15 @@ class Frame<R> {
    })
  }

-  private writeMember(node: MemberExpression, value: unknown): Effect.Effect<unknown, unknown, R> {
+  private writeMember(node: MemberExpression, value: Value): Effect.Effect<Value, unknown, R> {
    return this.modifyMember(node, () => Effect.succeed({ write: true, next: value, result: value }))
  }

  private evaluateDeleteExpression(argument: Expression): Effect.Effect<boolean, unknown, R> {
    const target = argument.type === "ChainExpression" ? argument.expression : argument
-    if (target.type !== "MemberExpression") {
-      throw typeError("Only data fields may be deleted.", argument)
-    }
+    if (target.type === "Identifier") throw typeError("Only data fields may be deleted.", argument)
+    // `delete <non-reference>` evaluates the operand and is true, as in JS.
+    if (target.type !== "MemberExpression") return Effect.map(this.evaluateExpression(target), () => true)
    return Effect.map(this.getMemberReference(target), (reference) => {
      if (reference === OptionalShortCircuit) return true
      if (reference instanceof ToolReference || "value" in reference || reference.receiver !== reference.target) {
@@ -2140,8 +2132,8 @@ class Frame<R> {
  // Resolve side-effecting object and key expressions exactly once.
  private modifyMember(
    node: MemberExpression,
-    compute: (current: unknown) => Effect.Effect<{ write: boolean; next: unknown; result: unknown }, unknown, R>,
-  ): Effect.Effect<unknown, unknown, R> {
+    compute: (current: Value) => Effect.Effect<{ write: boolean; next: Value; result: Value }, unknown, R>,
+  ): Effect.Effect<Value, unknown, R> {
    const self = this
    return Effect.gen(function* () {
      const reference = yield* self.getMemberReference(node)
@@ -2161,7 +2153,7 @@ class Frame<R> {
    })
  }

-  private assignToReference(target: Obj, key: PropertyKey, next: unknown, node: AstNode): void {
+  private assignToReference(target: Obj, key: PropertyKey, next: Value, node: AstNode): void {
    const written = (() => {
      try {
        rejectCircularInsertion(
@@ -2179,12 +2171,9 @@ class Frame<R> {
    throw typeError(`Cannot assign to read only property '${String(key)}'.`, node)
  }

-  private toPropertyKey(value: unknown, node: AstNode): PropertyKey {
-    if (typeof value === "string" || typeof value === "number") {
-      return value
-    }
-    if (value === AsyncIteratorSymbol || value === IteratorSymbol) return value
-
-    throw typeError("Property key must be a string or number, or Symbol.asyncIterator/Symbol.iterator.", node)
+  // ToPropertyKey: anything else becomes its string form, so `counts[row.category]` works when the field is null.
+  private toPropertyKey(value: Value): PropertyKey {
+    if (typeof value === "string" || typeof value === "number" || typeof value === "symbol") return value
+    return coerceToString(value)
  }
 }
@@ -1,5 +1,5 @@
 import { Effect } from "effect"
-import { define, hidden, Native, Arr, ErrorObj, Obj } from "./objects.js"
+import { define, hidden, Native, Arr, ErrorObj, Obj, type Value } from "./objects.js"

 export const errorTypes = [
  "Error",
@@ -35,6 +35,7 @@ const builtins = [
  "TextDecoder",
  "Promise",
  "Iterator",
+  "IteratorHelper",
  "AsyncIterator",
  "Generator",
  "AsyncGenerator",
@@ -52,6 +53,14 @@ export const createErrorValue = (prototype: Obj, message: string | undefined): E
  return value
 }

+/** The prototype a primitive reads its methods from without being boxed; none for null, undefined, and symbols. */
+export const primitivePrototype = (builtins: Builtins, value: Value): Obj | undefined => {
+  if (typeof value === "string") return builtins.String
+  if (typeof value === "number") return builtins.Number
+  if (typeof value === "boolean") return builtins.Boolean
+  return undefined
+}
+
 export const createBuiltins = (): Builtins => {
  const object = new Obj(null)
  // Function.prototype is itself callable and returns undefined.
@@ -87,6 +96,7 @@ export const createBuiltins = (): Builtins => {
    TextDecoder: plain(),
    Promise: plain(),
    Iterator: iterator,
+    IteratorHelper: new Obj(iterator),
    AsyncIterator: asyncIterator,
    Generator: new Obj(iterator),
    AsyncGenerator: new Obj(asyncIterator),
@@ -2,7 +2,7 @@ import type { Node } from "acorn"
 import { Context } from "effect"
 import type { ErrorType } from "./intrinsics.js"
 import type { DiagnosticKind } from "../codemode.js"
-import type { ErrorObj } from "./objects.js"
+import type { ErrorObj, Value } from "./objects.js"

 /** Any parsed node; the interpreter narrows on `type` and reads `loc` for diagnostics. */
 export type AstNode = Node
@@ -14,13 +14,13 @@ export const CallSite = Context.Reference<{ readonly node?: AstNode; readonly de

 export type Binding = {
  mutable: boolean
-  value: unknown
+  value: Value
  initialized?: boolean
 }

 export type StatementResult =
  | { kind: "none" }
-  | { kind: "return"; value: unknown }
+  | { kind: "return"; value: Value }
  | { kind: "break"; label?: string }
  | { kind: "continue"; label?: string }

@@ -31,11 +31,11 @@ export const IteratorSymbol: unique symbol = Symbol("codemode.iterator")
 export const IteratorSymbols = [AsyncIteratorSymbol, IteratorSymbol] as const

 export class Throw {
-  constructor(readonly value: unknown) {}
+  constructor(readonly value: Value) {}
 }

 export class GeneratorReturn {
-  constructor(readonly value: unknown) {}
+  constructor(readonly value: Value) {}
 }

 export const OptionalShortCircuit: unique symbol = Symbol("codemode.optional-short-circuit")
@@ -83,12 +83,10 @@ export const unsupportedSyntax = (kind: string, node: AstNode): PendingThrow =>
    [supportedSyntaxMessage],
  )

-export const isRecord = (value: unknown): value is Record<string, unknown> =>
-  typeof value === "object" && value !== null
-
+// Acorn lines are 1-based and its columns are 0-based. Diagnostics use 1-based columns of the submitted source.
 export const sourceLocation = (node: AstNode): { readonly line: number; readonly column: number } => ({
-  line: Math.max(1, (node.loc?.start.line ?? 2) - 1),
-  column: Math.max(1, (node.loc?.start.column ?? 4) - 3),
+  line: node.loc?.start.line ?? 1,
+  column: (node.loc?.start.column ?? 0) + 1,
 })

 export const formatLocation = (node?: AstNode): string => {
@@ -1,18 +1,18 @@
 import { Effect } from "effect"
 import type { Builtins } from "./intrinsics.js"
 import { typeError } from "./model.js"
-import { type Callable, define, frozen, hidden, Native, type NativeOptions, Obj } from "./objects.js"
+import { type Callable, define, frozen, hidden, Native, type NativeOptions, Obj, type Value } from "./objects.js"
 import { describeValue } from "./references.js"

-/** A native function body: a plain value, a thrown `PendingThrow`, or an Effect. */
-export type Impl = (thisValue: unknown, args: Array<unknown>) => unknown
+/** A native function body: a value, a thrown `PendingThrow`, or an Effect of a value. */
+export type Impl = (thisValue: Value, args: Array<Value>) => Value | Effect.Effect<Value, unknown, unknown>

 // The dispatch in `Frame.call` suspends every native call, so a synchronous throw here is a defect.
 const lift =
  <R>(impl: Impl) =>
-  (thisValue: unknown, args: Array<unknown>): Effect.Effect<unknown, unknown, R> => {
+  (thisValue: Value, args: Array<Value>): Effect.Effect<Value, unknown, R> => {
    const result = impl(thisValue, args)
-    return Effect.isEffect(result) ? (result as Effect.Effect<unknown, unknown, R>) : Effect.succeed(result)
+    return Effect.isEffect(result) ? (result as Effect.Effect<Value, unknown, R>) : Effect.succeed(result)
  }

 export const native = <R>(builtins: Builtins, options: NativeOptions<R>): Native<R> =>
@@ -27,7 +27,7 @@ export const methods = (builtins: Builtins, target: Obj, table: ReadonlyArray<Me
  for (const [name, length, impl] of table) define(target, name, fn(builtins, name, length, impl), hidden)
 }

-export const constants = (target: Obj, table: Record<string, unknown>): void => {
+export const constants = (target: Obj, table: Record<string, Value>): void => {
  for (const [name, value] of Object.entries(table)) define(target, name, value, frozen)
 }

@@ -54,7 +54,7 @@ export const prototypeFrom = (newTarget: Callable, fallback: Obj): Obj => {
 /** Narrows a method receiver to the built-in it belongs to, or throws the TypeError JS would. */
 export const receiver = <T extends Obj>(
  cls: abstract new (...args: never) => T,
-  thisValue: unknown,
+  thisValue: Value,
  method: string,
 ): T => {
  if (thisValue instanceof cls) return thisValue
@@ -1,5 +1,7 @@
 import type { BlockStatement, Expression, Pattern } from "acorn"
-import type { Effect, Fiber } from "effect"
+import { Effect, type Fiber } from "effect"
+import { ToolReference } from "../tool-runtime.js"
+import type { Builtins } from "./intrinsics.js"
 import { checkArrayLength } from "./limits.js"
 import {
  AsyncIteratorSymbol,
@@ -16,12 +18,12 @@ export type Attributes = {
  readonly configurable: boolean
 }

-export type Getter = (receiver: unknown) => unknown
-export type Setter = (receiver: unknown, value: unknown) => void
+export type Getter = (receiver: Value) => Value
+export type Setter = (receiver: Value, value: Value) => void

 /** One own property: a data slot or a native accessor pair. */
 export type Slot =
-  | { value: unknown; writable: boolean; enumerable: boolean; configurable: boolean }
+  | { value: Value; writable: boolean; enumerable: boolean; configurable: boolean }
  | { get: Getter | undefined; set: Setter | undefined; enumerable: boolean; configurable: boolean }

 /** Ordinary assignment: writable, enumerable, configurable. */
@@ -33,33 +35,122 @@ export const readonly: Attributes = { writable: false, enumerable: false, config
 /** Constants such as `Math.PI` and a constructor's `prototype`. */
 export const frozen: Attributes = { writable: false, enumerable: false, configurable: false }

-/** An object owned by the program: own properties plus a prototype link. */
+/**
+ * An object owned by the program: own properties plus a prototype link. Subclasses answer, in one place, how a
+ * built-in kind of object prints, coerces, iterates, and crosses to the host.
+ */
 export class Obj {
  readonly props = new Map<string | symbol, Slot>()
  constructor(public proto: Obj | null) {}
+
+  /** The class name `Object.prototype.toString` reports: `[object Map]`. */
+  readonly tag: string = "Object"
+
+  /** How diagnostics refer to a value of this kind. */
+  get describe(): string {
+    if (this.tag === "Object") return "a data object"
+    return `${/^[AEIO]/.test(this.tag) ? "an" : "a"} ${this.tag}`
+  }
+
+  /** ToString without consulting program-defined methods. */
+  toString(): string {
+    return `[object ${this.tag}]`
+  }
+
+  /** ToPrimitive without consulting program-defined methods: only a Date answers a number hint differently. */
+  toPrimitive(hint: "default" | "number" | "string"): string | number {
+    return this.toString()
+  }
+
+  /** ToNumber without consulting program-defined methods. */
+  toNumber(): number {
+    return Number(this.toPrimitive("number"))
+  }
+
+  /** How `console.log` shows the value; `item` formats a child with cycle and depth tracking. */
+  inspect(item: (value: Value) => string): string {
+    return `{${entries(this)
+      .map(([key, value]) => `${JSON.stringify(key)}:${item(value)}`)
+      .join(",")}}`
+  }
+
+  /** A copy the host can hold; `item` converts a child. A `__proto__` key never reaches host code. */
+  toHost(item: (value: Value) => unknown): unknown {
+    return Object.fromEntries(
+      entries(this)
+        .filter(([key]) => key !== "__proto__")
+        .map(([key, value]) => [key, item(value)]),
+    )
+  }
+
+  /** The built-in iteration `for...of` and spread use, when this kind of object has one. */
+  iterator(builtins: Builtins): Iterator<Value, undefined> | undefined {
+    return undefined
+  }
 }

 export class Arr extends Obj {
+  override readonly tag = "Array"
  constructor(
    proto: Obj,
-    readonly items: Array<unknown> = [],
+    readonly items: Array<Value> = [],
  ) {
    super(proto)
  }
+  override get describe() {
+    return "an array"
+  }
+  override toString() {
+    return this.items.map((item) => (item === null || item === undefined ? "" : coerceToString(item))).join(",")
+  }
+  override inspect(item: (value: Value) => string) {
+    return `[${this.items.map(item).join(",")}]`
+  }
+  override toHost(item: (value: Value) => unknown) {
+    return this.items.map(item)
+  }
+  override iterator() {
+    return this.items.values()
+  }
 }

 /** An object with the [[ErrorData]] slot: what `Error.prototype.toString` and the host boundary recognize as an error. */
 export class ErrorObj extends Obj {
+  override readonly tag = "Error"
  /** The interpreter failure this error materialized from, so rethrowing it keeps the diagnostic kind and location. */
  host?: PendingThrow
+  /** Error.prototype.toString: "name: message", or just one when the other is empty. */
+  override toString() {
+    const name = get(this, "name")
+    const message = get(this, "message")
+    const shownName = typeof name === "string" ? name : "Error"
+    const shownMessage = typeof message === "string" ? message : ""
+    if (shownMessage === "") return shownName
+    if (shownName === "") return shownMessage
+    return `${shownName}: ${shownMessage}`
+  }
+  override inspect() {
+    return this.toString()
+  }
 }

-export abstract class Callable extends Obj {
+/** Interpreter machinery a program can hold but never inspect, serialize, or hand to the host. */
+export abstract class Opaque extends Obj {
+  override inspect() {
+    return "[opaque reference]"
+  }
+}
+
+export abstract class Callable extends Opaque {
+  override readonly tag = "Function"
  constructor(proto: Obj, name: string, length: number) {
    super(proto)
    define(this, "length", length, readonly)
    define(this, "name", name, readonly)
  }
+  override get describe() {
+    return "a function"
+  }
 }

 export class Fn extends Callable {
@@ -68,7 +159,7 @@ export class Fn extends Callable {
    name: string,
    readonly parameters: ReadonlyArray<Pattern>,
    readonly body: BlockStatement | Expression,
-    readonly capturedScopes: ReadonlyArray<Map<string, Binding>>,
+    readonly capturedScopes: Array<Map<string, Binding>>,
    readonly async: boolean,
    readonly generator: boolean,
  ) {
@@ -77,8 +168,8 @@ export class Fn extends Callable {
  }
 }

-export type NativeCall<R> = (thisValue: unknown, args: Array<unknown>) => Effect.Effect<unknown, unknown, R>
-export type NativeConstruct<R> = (args: Array<unknown>, newTarget: Callable) => Effect.Effect<unknown, unknown, R>
+export type NativeCall<R> = (thisValue: Value, args: Array<Value>) => Effect.Effect<Value, unknown, R>
+export type NativeConstruct<R> = (args: Array<Value>, newTarget: Callable) => Effect.Effect<Value, unknown, R>

 export type NativeOptions<R> = {
  readonly name: string
@@ -103,79 +194,182 @@ export class Native<R = never> extends Callable {
  }
 }

-export class PromiseObj extends Obj {
+export class PromiseObj extends Opaque {
+  override readonly tag = "Promise"
  constructor(
    proto: Obj,
-    readonly fiber: Fiber.Fiber<unknown, unknown>,
+    readonly fiber: Fiber.Fiber<Value, unknown>,
  ) {
    super(proto)
  }
+  override get describe() {
+    return "an un-awaited Promise"
+  }
+  override inspect() {
+    return "[Promise (await it to get its value)]"
+  }
 }

-export class GeneratorObj extends Obj {
+export class GeneratorObj extends Opaque {
+  override readonly tag = "Generator"
  constructor(
    proto: Obj,
    readonly asynchronous: boolean,
-    readonly request: (kind: GeneratorRequestKind, value: unknown) => Effect.Effect<unknown, unknown, unknown>,
+    readonly request: (kind: GeneratorRequestKind, value: Value) => Effect.Effect<Value, unknown, unknown>,
  ) {
    super(proto)
  }
+  override get describe() {
+    return "a generator"
+  }
 }

-/** A built-in collection iterator: live over the host collection, yielding program values. */
-export class IteratorObj extends Obj {
+/** One pull from an iterator, as `for...of` sees it. */
+export type Step = { readonly done: boolean; readonly value: Value }
+
+/** How the interpreter drives any iterator: pull the next step, or close it early. */
+export type Cursor<R = unknown> = {
+  readonly next: Effect.Effect<Step, unknown, R>
+  readonly close: Effect.Effect<void, unknown, R>
+}
+
+/** A cursor over a host iterator; there is nothing to close. */
+export const hostCursor = (iterator: Iterator<Value, undefined>): Cursor<never> => ({
+  next: Effect.sync(() => {
+    const step = iterator.next()
+    return { done: Boolean(step.done), value: step.value }
+  }),
+  close: Effect.void,
+})
+
+/** A built-in iterator: a live cursor over a host collection or an iterator helper, yielding program values. */
+export class IteratorObj extends Opaque {
+  override readonly tag = "Iterator"
  constructor(
    proto: Obj,
-    readonly iterator: IteratorObject<unknown>,
+    readonly cursor: Cursor,
  ) {
    super(proto)
  }
+  override get describe() {
+    return "an iterator"
+  }
 }

-export class DateObj extends Obj {
+/** A built-in iterator over a host iterator, e.g. `array.values()`. */
+export const hostIterator = (builtins: Builtins, iterator: Iterator<Value, undefined>): IteratorObj =>
+  new IteratorObj(builtins.Iterator, hostCursor(iterator))
+
+/** A built-in object around a host value: data-like, so it prints as itself and crosses to extensions as a copy. */
+export abstract class Wrapper extends Obj {
+  override inspect(item: (value: Value) => string) {
+    return this.toString()
+  }
+}
+
+export class DateObj extends Wrapper {
+  override readonly tag = "Date"
  constructor(
    proto: Obj,
    public time: number,
  ) {
    super(proto)
  }
+  override toString() {
+    return Number.isFinite(this.time) ? new Date(this.time).toISOString() : "Invalid Date"
+  }
+  override toPrimitive(hint: "default" | "number" | "string") {
+    return hint === "number" ? this.time : this.toString()
+  }
+  override toHost() {
+    return new Date(this.time)
+  }
 }

-export class RegExpObj extends Obj {
+export class RegExpObj extends Wrapper {
+  override readonly tag = "RegExp"
  readonly regex: RegExp
  constructor(proto: Obj, pattern: string, flags: string) {
    super(proto)
    this.regex = new RegExp(pattern, flags)
  }
+  override toString() {
+    return `/${this.regex.source}/${this.regex.flags}`
+  }
+  override toHost() {
+    return new RegExp(this.regex.source, this.regex.flags)
+  }
 }

-export class MapObj extends Obj {
-  readonly map = new Map<unknown, unknown>()
+export class MapObj extends Wrapper {
+  override readonly tag = "Map"
+  readonly map = new Map<Value, Value>()
+  override inspect(item: (value: Value) => string) {
+    return `Map(${this.map.size}) [${[...this.map].map(([key, value]) => `[${item(key)},${item(value)}]`).join(",")}]`
+  }
+  override toHost(item: (value: Value) => unknown) {
+    return new Map([...this.map].map(([key, value]) => [item(key), item(value)]))
+  }
+  override iterator(builtins: Builtins) {
+    return this.map.entries().map((entry) => new Arr(builtins.Array, entry))
+  }
 }

-export class SetObj extends Obj {
-  readonly set = new Set<unknown>()
+export class SetObj extends Wrapper {
+  override readonly tag = "Set"
+  readonly set = new Set<Value>()
+  override inspect(item: (value: Value) => string) {
+    return `Set(${this.set.size}) [${[...this.set].map(item).join(",")}]`
+  }
+  override toHost(item: (value: Value) => unknown) {
+    return new Set([...this.set].map(item))
+  }
+  override iterator() {
+    return this.set.values()
+  }
 }

-export class URLSearchParamsObj extends Obj {
+export class URLSearchParamsObj extends Wrapper {
+  override readonly tag = "URLSearchParams"
  constructor(
    proto: Obj,
    readonly params: URLSearchParams,
  ) {
    super(proto)
  }
+  override toString() {
+    return this.params.toString()
+  }
+  override toHost() {
+    return new URLSearchParams(this.params)
+  }
+  override iterator(builtins: Builtins) {
+    return this.params.entries().map((entry) => new Arr(builtins.Array, entry))
+  }
 }

-export class HeadersObj extends Obj {
+export class HeadersObj extends Wrapper {
+  override readonly tag = "Headers"
  constructor(
    proto: Obj,
    readonly headers: Headers,
  ) {
    super(proto)
  }
+  override inspect() {
+    return `Headers ${JSON.stringify(Object.fromEntries(this.headers))}`
+  }
+  override toHost() {
+    return new Headers(this.headers)
+  }
+  override iterator(builtins: Builtins) {
+    // Bun's Headers typings lack the iterator helpers, so the host iterator is lifted first.
+    return Iterator.from(this.headers.entries()).map((entry) => new Arr(builtins.Array, entry))
+  }
 }

-export class URLObj extends Obj {
+export class URLObj extends Wrapper {
+  override readonly tag = "URL"
  readonly searchParams: URLSearchParamsObj
  constructor(
    proto: Obj,
@@ -185,30 +379,58 @@ export class URLObj extends Obj {
    super(proto)
    this.searchParams = new URLSearchParamsObj(searchParamsProto, url.searchParams)
  }
+  override toString() {
+    return this.url.href
+  }
+  override toHost() {
+    return new URL(this.url.href)
+  }
 }

 /** A `Uint8Array`: the host array does the byte clamping and ignores out-of-range writes, as JS does. */
-export class Bytes extends Obj {
+export class Bytes extends Wrapper {
+  override readonly tag = "Uint8Array"
  constructor(
    proto: Obj,
    readonly bytes: Uint8Array,
  ) {
    super(proto)
  }
+  override toString() {
+    return this.bytes.join(",")
+  }
+  override inspect() {
+    return `Uint8Array(${this.bytes.length}) [${this.bytes.join(",")}]`
+  }
+  override toHost() {
+    return new Uint8Array(this.bytes)
+  }
+  override iterator() {
+    return this.bytes.values()
+  }
 }

-/** Built-in objects that wrap a host value; data-like, but never plain data. */
-export const isWrapper = (
-  value: unknown,
-): value is DateObj | RegExpObj | MapObj | SetObj | URLObj | URLSearchParamsObj | HeadersObj | Bytes =>
-  value instanceof DateObj ||
-  value instanceof RegExpObj ||
-  value instanceof MapObj ||
-  value instanceof SetObj ||
-  value instanceof URLObj ||
-  value instanceof URLSearchParamsObj ||
-  value instanceof HeadersObj ||
-  value instanceof Bytes
+/** Every value a program can hold. Host values never appear here; they are copied in at the boundaries. */
+export type Value = string | number | boolean | null | undefined | symbol | Obj | ToolReference
+
+/** ToString without consulting program-defined methods. */
+export const coerceToString = (value: Value): string => (value instanceof Obj ? value.toString() : String(value))
+
+/** ToNumber without consulting program-defined methods; tool references are not numbers. */
+export const coerceToNumber = (value: Value): number => {
+  if (value instanceof Obj) return value.toNumber()
+  return value instanceof ToolReference ? Number.NaN : Number(value)
+}
+
+/** ToIntegerOrInfinity: NaN is 0, fractions truncate. */
+export const coerceToInteger = (value: Value): number => {
+  const number = coerceToNumber(value)
+  return Number.isNaN(number) ? 0 : Math.trunc(number)
+}
+
+/** Values that cannot cross the data boundary: opaque machinery and host-backed wrappers. */
+export const isRuntimeReference = (value: Value): boolean =>
+  value instanceof Opaque || value instanceof Wrapper || value instanceof ToolReference

 const MAX_ARRAY_INDEX = 4_294_967_295

@@ -226,7 +448,7 @@ type Indexed = Arr | Bytes

 const isIndexed = (target: Obj): target is Indexed => target instanceof Arr || target instanceof Bytes

-const elements = (target: Indexed): Array<unknown> | Uint8Array => (target instanceof Arr ? target.items : target.bytes)
+const elements = (target: Indexed): Array<Value> | Uint8Array => (target instanceof Arr ? target.items : target.bytes)

 const index = (target: Obj, key: string | symbol): number | undefined =>
  isIndexed(target) && typeof key === "string" ? parseArrayIndex(key) : undefined
@@ -247,18 +469,18 @@ export const own = (target: Obj, key: PropertyKey): Slot | undefined => {
  return target.props.get(name)
 }

-const read = (slot: Slot, receiver: unknown): unknown =>
+const read = (slot: Slot, receiver: Value): Value =>
  "value" in slot ? slot.value : slot.get === undefined ? undefined : slot.get(receiver)

 export const hasOwn = (target: Obj, key: PropertyKey): boolean => own(target, key) !== undefined

-export const getOwn = (target: Obj, key: PropertyKey): unknown => {
+export const getOwn = (target: Obj, key: PropertyKey): Value => {
  const slot = own(target, key)
  return slot === undefined ? undefined : read(slot, target)
 }

 /** [[Get]]: walks the prototype chain; accessors see `receiver`, which is the primitive for wrapper prototypes. */
-export const get = (target: Obj, key: PropertyKey, receiver: unknown = target): unknown => {
+export const get = (target: Obj, key: PropertyKey, receiver: Value = target): Value => {
  for (let current: Obj | null = target; current !== null; current = current.proto) {
    const slot = own(current, key)
    if (slot !== undefined) return read(slot, receiver)
@@ -273,14 +495,14 @@ export const has = (target: Obj, key: PropertyKey): boolean => {
  return false
 }

-export const hasPrototype = (value: unknown, proto: Obj): boolean => {
+export const hasPrototype = (value: Value, proto: Obj): boolean => {
  for (let current = value instanceof Obj ? value.proto : null; current !== null; current = current.proto) {
    if (current === proto) return true
  }
  return false
 }

-const writeElement = (target: Indexed, name: string | symbol, value: unknown): boolean | undefined => {
+const writeElement = (target: Indexed, name: string | symbol, value: Value): boolean | undefined => {
  const at = index(target, name)
  if (at !== undefined) {
    if (target instanceof Bytes) target.bytes[at] = typeof value === "number" ? value : Number(value)
@@ -296,7 +518,7 @@ const writeElement = (target: Indexed, name: string | symbol, value: unknown): b
 }

 /** [[Set]]: an inherited setter or read-only property decides before an own data property is created. */
-export const set = (target: Obj, key: PropertyKey, value: unknown): boolean => {
+export const set = (target: Obj, key: PropertyKey, value: Value): boolean => {
  const name = canonical(key)
  for (let current: Obj | null = target; current !== null; current = current.proto) {
    const slot = own(current, name)
@@ -324,7 +546,7 @@ export const set = (target: Obj, key: PropertyKey, value: unknown): boolean => {
 }

 /** [[DefineOwnProperty]] for a data property, ignoring the chain. */
-export const define = (target: Obj, key: PropertyKey, value: unknown, attrs: Attributes = data): void => {
+export const define = (target: Obj, key: PropertyKey, value: Value, attrs: Attributes = data): void => {
  const name = canonical(key)
  if (isIndexed(target) && writeElement(target, name, value) !== undefined) return
  target.props.set(name, { value, ...attrs })
@@ -375,9 +597,9 @@ export const keys = (target: Obj): Array<string> =>
  ownKeys(target).filter((key): key is string => typeof key === "string" && enumerable(target, key))

 /** Own enumerable string entries: `Object.entries` and serialization. */
-export const entries = (target: Obj): Array<[string, unknown]> => keys(target).map((key) => [key, getOwn(target, key)])
+export const entries = (target: Obj): Array<[string, Value]> => keys(target).map((key) => [key, getOwn(target, key)])

-export const record = (proto: Obj, fields: Record<string, unknown>): Obj => {
+export const record = (proto: Obj, fields: Record<string, Value>): Obj => {
  const target = new Obj(proto)
  for (const [key, value] of Object.entries(fields)) define(target, key, value)
  return target
@@ -2,15 +2,15 @@ import { Cause, Deferred, Effect, Exit, Fiber, Scope } from "effect"
 import type { Diagnostic } from "../codemode.js"
 import { MAX_PENDING_PROMISES } from "./limits.js"
 import { CallSite, Throw, rangeError, typeError } from "./model.js"
-import { Callable, define, get, hidden, Arr, Fn, Obj, PromiseObj, record } from "./objects.js"
+import { Callable, define, get, hidden, Arr, Fn, Obj, PromiseObj, record, type Value } from "./objects.js"
 import { constructor, fn, methods, native, receiver, requiresNew } from "./native.js"
 import { createAggregateErrorValue, locate, materialize, normalizeError } from "./errors.js"
-import { typeofValue } from "./references.js"
+import { describeValue, typeofValue } from "./references.js"
 import { applyCollectionCallback, isSupportedCallback } from "./callback.js"
 import type { Interpreter } from "./interpreter.js"

 // A `resolve`/`reject` handed to an executor or thenable: calling it settles the capability.
-const capability = <R>(ctx: Interpreter<R>, name: string, settle: (value: unknown) => void) =>
+const capability = <R>(ctx: Interpreter<R>, name: string, settle: (value: Value) => void) =>
  fn(ctx.builtins, name, 1, (_, args) => {
    settle(args[0])
    return undefined
@@ -31,7 +31,7 @@ export class Pending<R> {

  // Resolution bodies need the promise's own identity to reject `resolve(promise)` self-resolution.
  createWithSelf(
-    body: (self: { promise?: PromiseObj }) => Effect.Effect<unknown, unknown, R>,
+    body: (self: { promise?: PromiseObj }) => Effect.Effect<Value, unknown, R>,
  ): Effect.Effect<PromiseObj, never, R> {
    const self: { promise?: PromiseObj } = {}
    return Effect.map(this.create(body(self)), (promise) => {
@@ -40,7 +40,7 @@ export class Pending<R> {
    })
  }

-  create(effect: Effect.Effect<unknown, unknown, R>): Effect.Effect<PromiseObj, never, R> {
+  create(effect: Effect.Effect<Value, unknown, R>): Effect.Effect<PromiseObj, never, R> {
    return Effect.flatMap(CallSite, (site) => {
      if (this.active.size >= MAX_PENDING_PROMISES) {
        throw rangeError(
@@ -79,7 +79,7 @@ export class Pending<R> {
    if (id !== undefined) this.failures.delete(id)
  }

-  await(promise: PromiseObj): Effect.Effect<Exit.Exit<unknown, unknown>> {
+  await(promise: PromiseObj): Effect.Effect<Exit.Exit<Value, unknown>> {
    return Fiber.await(promise.fiber)
  }

@@ -105,9 +105,9 @@ export class Pending<R> {

 export const resolvePromiseValue = <R>(
  ctx: Interpreter<R>,
-  value: unknown,
+  value: Value,
  own?: { promise?: PromiseObj },
-): Effect.Effect<unknown, unknown, R> => {
+): Effect.Effect<Value, unknown, R> => {
  if (own?.promise !== undefined && value === own.promise) {
    return Effect.die(typeError("Chaining cycle detected: a promise cannot resolve with itself."))
  }
@@ -119,7 +119,7 @@ export const resolvePromiseValue = <R>(
  return Effect.gen(function* () {
    // Promise resolution invokes a thenable's method in a later job.
    yield* Effect.yieldNow
-    const deferred = Deferred.makeUnsafe<unknown, unknown>()
+    const deferred = Deferred.makeUnsafe<Value, unknown>()
    const resolve = capability(ctx, "resolve", (result) => Deferred.doneUnsafe(deferred, Exit.succeed(result)))
    const reject = capability(ctx, "reject", (reason) => Deferred.doneUnsafe(deferred, Exit.fail(new Throw(reason))))
    const executed = yield* Effect.exit(ctx.call(then, value, [resolve, reject]))
@@ -131,29 +131,46 @@ export const resolvePromiseValue = <R>(
  })
 }

-export const resolvePromise = <R>(ctx: Interpreter<R>, value: unknown): Effect.Effect<PromiseObj, never, R> => {
+export const resolvePromise = <R>(ctx: Interpreter<R>, value: Value): Effect.Effect<PromiseObj, never, R> => {
  if (value instanceof PromiseObj) return Effect.succeed(value)
  return ctx.pending.createWithSelf((self) => resolvePromiseValue(ctx, value, self))
 }

-const promiseStatics = ["all", "allSettled", "race", "any", "resolve", "reject"] as const
+const promiseStatics = ["all", "allSettled", "race", "any", "resolve", "reject", "withResolvers", "try"] as const

 const invokePromiseMethod = <R>(
  ctx: Interpreter<R>,
  name: (typeof promiseStatics)[number],
-  args: Array<unknown>,
-): Effect.Effect<unknown, unknown, R> => {
+  args: Array<Value>,
+): Effect.Effect<Value, unknown, R> => {
  if (name === "resolve") {
    return resolvePromise(ctx, args[0])
  }
  if (name === "reject") {
    return ctx.pending.create(Effect.fail(new Throw(args[0])))
  }
+  if (name === "withResolvers") {
+    return Effect.map(promiseCapability(ctx), (made) =>
+      record(ctx.builtins.Object, { promise: made.promise, resolve: made.resolve, reject: made.reject }),
+    )
+  }
+  if (name === "try") {
+    if (typeofValue(args[0]) !== "function") {
+      throw typeError(`Promise.try expects a function, received ${describeValue(args[0])}.`)
+    }
+    return Effect.flatMap(Effect.exit(ctx.call(args[0], undefined, args.slice(1))), (called) => {
+      if (Exit.isSuccess(called)) return resolvePromise(ctx, called.value)
+      if (Cause.hasInterruptsOnly(called.cause)) return Effect.failCause(called.cause)
+      return ctx.pending.create(Effect.fail(Cause.squash(called.cause)))
+    })
+  }

  return ctx.pending.create(
    Effect.gen(function* () {
      const cursor = yield* ctx.iterate(args[0])
-      if (cursor === undefined) throw typeError(`Promise.${name} expects an array or other synchronous iterable.`)
+      if (cursor === undefined) {
+        throw typeError(`Promise.${name} expects a synchronous iterable, received ${describeValue(args[0])}.`)
+      }
      const items: Array<PromiseObj> = []
      while (true) {
        const step = yield* cursor.next
@@ -175,7 +192,7 @@ const invokePromiseMethod = <R>(
        )
      }
      if (name === "allSettled") {
-        const outcomes: Array<unknown> = []
+        const outcomes: Array<Value> = []
        for (const item of items) {
          const exit = yield* ctx.pending.await(item)
          if (Exit.isSuccess(exit)) {
@@ -223,8 +240,8 @@ const invokePromiseMethod = <R>(
 const instanceMethod = <R>(
  ctx: Interpreter<R>,
  name: "then" | "catch" | "finally",
-  thisValue: unknown,
-  args: Array<unknown>,
+  thisValue: Value,
+  args: Array<Value>,
 ): Effect.Effect<PromiseObj, unknown, R> => {
  const method = `Promise.prototype.${name}`
  const promise = receiver(PromiseObj, thisValue, method)
@@ -237,23 +254,30 @@ const instanceMethod = <R>(
  return chainReaction(ctx, promise, onFulfilled, onRejected, method)
 }

-const constructPromise = <R>(ctx: Interpreter<R>, executor: unknown): Effect.Effect<PromiseObj, unknown, R> => {
-  if (!(executor instanceof Fn)) {
-    throw typeError("new Promise(...) expects an executor function (e.g. new Promise((resolve, reject) => { ... })).")
-  }
-  return Effect.gen(function* () {
-    const deferred = Deferred.makeUnsafe<unknown, unknown>()
+/** NewPromiseCapability: a pending promise with the resolve/reject callables that settle it exactly once. */
+const promiseCapability = <R>(ctx: Interpreter<R>) =>
+  Effect.gen(function* () {
+    const deferred = Deferred.makeUnsafe<Value, unknown>()
    const promise = yield* ctx.pending.createWithSelf((self) =>
      Effect.flatMap(Deferred.await(deferred), (value) => resolvePromiseValue(ctx, value, self)),
    )
    const resolve = capability(ctx, "resolve", (value) => Deferred.doneUnsafe(deferred, Exit.succeed(value)))
    const reject = capability(ctx, "reject", (value) => Deferred.doneUnsafe(deferred, Exit.fail(new Throw(value))))
-    const executed = yield* Effect.exit(ctx.call(executor, undefined, [resolve, reject]))
+    return { promise, resolve, reject, deferred }
+  })
+
+const constructPromise = <R>(ctx: Interpreter<R>, executor: Value): Effect.Effect<PromiseObj, unknown, R> => {
+  if (!(executor instanceof Fn)) {
+    throw typeError("new Promise(...) expects an executor function (e.g. new Promise((resolve, reject) => { ... })).")
+  }
+  return Effect.gen(function* () {
+    const made = yield* promiseCapability(ctx)
+    const executed = yield* Effect.exit(ctx.call(executor, undefined, [made.resolve, made.reject]))
    if (!Exit.isSuccess(executed)) {
      if (Cause.hasInterruptsOnly(executed.cause)) return yield* Effect.failCause(executed.cause)
-      Deferred.doneUnsafe(deferred, Exit.fail(Cause.squash(executed.cause)))
+      Deferred.doneUnsafe(made.deferred, Exit.fail(Cause.squash(executed.cause)))
    }
-    return promise
+    return made.promise
  })
 }

@@ -262,10 +286,10 @@ const settleAfterTurn = <A, E, R>(body: Effect.Effect<A, E, R>): Effect.Effect<A
  Effect.flatMap(Effect.exit(body), (exit) => Effect.andThen(Effect.yieldNow, exit))

 class PromiseAnyFulfilled {
-  constructor(readonly value: unknown) {}
+  constructor(readonly value: Value) {}
 }

-const reactionHandler = (value: unknown, method: string): Callable | undefined => {
+const reactionHandler = (value: Value, method: string): Callable | undefined => {
  if (isSupportedCallback(value)) return value
  if (typeofValue(value) === "function") {
    throw typeError(
@@ -279,7 +303,7 @@ const reactionHandler = (value: unknown, method: string): Callable | undefined =
 const reactionExit = <R>(
  ctx: Interpreter<R>,
  source: PromiseObj,
-): Effect.Effect<Exit.Exit<unknown, unknown>, unknown, R> =>
+): Effect.Effect<Exit.Exit<Value, unknown>, unknown, R> =>
  Effect.gen(function* () {
    const exit = yield* ctx.pending.await(source)
    if (!Exit.isSuccess(exit) && Cause.hasInterruptsOnly(exit.cause)) return yield* Effect.failCause(exit.cause)
@@ -1,47 +1,18 @@
 import { ToolReference } from "../tool-runtime.js"
 import { invalidData } from "./model.js"
-import {
-  Callable,
-  getOwn,
-  isWrapper,
-  ownKeys,
-  Arr,
-  Bytes,
-  DateObj,
-  GeneratorObj,
-  IteratorObj,
-  MapObj,
-  Obj,
-  PromiseObj,
-  RegExpObj,
-  SetObj,
-  URLObj,
-  URLSearchParamsObj,
-  HeadersObj,
-} from "./objects.js"
+import { Callable, getOwn, isRuntimeReference, Obj, Opaque, ownKeys, type Value } from "./objects.js"

-/** Values that cannot cross the data boundary. */
-export const isRuntimeReference = (value: unknown): boolean =>
-  value instanceof Callable ||
-  value instanceof GeneratorObj ||
-  value instanceof IteratorObj ||
-  value instanceof ToolReference ||
-  value instanceof PromiseObj ||
-  isWrapper(value)
-
-function* childValues(value: object): Generator {
-  if (!(value instanceof Obj)) return
-  for (const key of ownKeys(value)) yield getOwn(value, key)
-}
+/** Interpreter machinery that is never data, unlike a Date or Map, which cross some boundaries as copies. */
+export const isOpaque = (value: Value): boolean => value instanceof Opaque || value instanceof ToolReference

 // Depth-first search over a value tree. `match` stops the walk; `skip` prunes a subtree without matching it.
 const find = (
-  value: unknown,
-  match: (current: unknown) => boolean,
-  skip: (current: unknown) => boolean,
+  value: Value,
+  match: (current: Value) => boolean,
+  skip: (current: Value) => boolean,
  seen: Set<object>,
 ): boolean => {
-  const pending: Array<Iterator<unknown>> = [[value].values()]
+  const pending: Array<Iterator<Value>> = [[value].values()]
  while (pending.length > 0) {
    const next = pending.at(-1)!.next()
    if (next.done) {
@@ -50,25 +21,28 @@ const find = (
    }
    const current = next.value
    if (match(current)) return true
-    if (current === null || typeof current !== "object" || skip(current) || seen.has(current)) continue
+    if (!(current instanceof Obj) || skip(current) || seen.has(current)) continue
    seen.add(current)
-    pending.push(childValues(current))
+    pending.push(
+      ownKeys(current)
+        .map((key) => getOwn(current, key))
+        .values(),
+    )
  }
  return false
 }

 const never = () => false

-export const containsRuntimeReference = (value: unknown): boolean => find(value, isRuntimeReference, never, new Set())
+export const containsRuntimeReference = (value: Value): boolean => find(value, isRuntimeReference, never, new Set())

-// Wrapper values are data here, not opaque interpreter references.
-export const containsOpaqueReference = (value: unknown): boolean =>
-  find(value, (current) => !isWrapper(current) && isRuntimeReference(current), isWrapper, new Set())
+export const containsOpaqueReference = (value: Value): boolean =>
+  find(value, isOpaque, (current) => isRuntimeReference(current) && !isOpaque(current), new Set())

 // Reject cycles before mutation so later boundary walks remain safe.
 export const rejectCircularInsertion = (
-  container: object,
-  value: unknown,
+  container: Obj,
+  value: Value,
  label: string,
  seen = new Set<object>(),
 ): void => {
@@ -77,27 +51,14 @@ export const rejectCircularInsertion = (
  }
 }

-export const describeValue = (value: unknown): string => {
+export const describeValue = (value: Value): string => {
  if (value === null || value === undefined) return String(value)
-  if (value instanceof Arr) return "an array"
-  if (value instanceof PromiseObj) return "an un-awaited Promise"
+  if (value instanceof Obj) return value.describe
  if (value instanceof ToolReference) return "a tool reference"
-  if (value instanceof DateObj) return "a Date"
-  if (value instanceof RegExpObj) return "a RegExp"
-  if (value instanceof MapObj) return "a Map"
-  if (value instanceof SetObj) return "a Set"
-  if (value instanceof URLObj) return "a URL"
-  if (value instanceof URLSearchParamsObj) return "a URLSearchParams"
-  if (value instanceof HeadersObj) return "a Headers"
-  if (value instanceof Bytes) return "a Uint8Array"
-  if (value instanceof GeneratorObj) return "a generator"
-  if (value instanceof IteratorObj) return "an iterator"
-  if (isRuntimeReference(value)) return "a function"
-  if (typeof value === "object") return "a data object"
  return `a ${typeof value}`
 }

-export const typeofValue = (value: unknown): string => {
+export const typeofValue = (value: Value): string => {
  if (value instanceof Callable) return "function"
  if (value instanceof ToolReference) return value.path.length > 0 ? "function" : "object"
  return typeof value
@@ -1,4 +1,5 @@
 import { type AstNode, type Binding, referenceError, typeError } from "./model.js"
+import type { Value } from "./objects.js"

 export class ScopeStack {
  private readonly scopes: Array<Map<string, Binding>>
@@ -15,7 +16,7 @@ export class ScopeStack {
    scope.set(name, { mutable, value: undefined, initialized: false })
  }

-  initialize(name: string, value: unknown, node: AstNode): void {
+  initialize(name: string, value: Value, node: AstNode): void {
    const binding = this.current().get(name)
    if (!binding || binding.initialized !== false) {
      throw typeError(`Identifier '${name}' has not been reserved for initialization.`, node)
@@ -24,7 +25,7 @@ export class ScopeStack {
    binding.initialized = true
  }

-  declare(name: string, value: unknown, mutable: boolean, node: AstNode): void {
+  declare(name: string, value: Value, mutable: boolean, node: AstNode): void {
    const scope = this.current()
    if (scope.has(name)) {
      throw typeError(`Identifier '${name}' has already been declared.`, node)
@@ -32,7 +33,7 @@ export class ScopeStack {
    scope.set(name, { mutable, value, initialized: true })
  }

-  get(name: string, node: AstNode): unknown {
+  get(name: string, node: AstNode): Value {
    const binding = this.resolve(name)

    if (!binding) {
@@ -46,7 +47,7 @@ export class ScopeStack {
    return binding.value
  }

-  set(name: string, value: unknown, node: AstNode): unknown {
+  set(name: string, value: Value, node: AstNode): Value {
    const binding = this.resolve(name)

    if (!binding) {
@@ -2,26 +2,36 @@ import { Effect } from "effect"
 import { constructor, type Method, methods, prototypeFrom, receiver } from "../interpreter/native.js"
 import { checkArrayLength, checkStringLength, MAX_ARRAY_LENGTH } from "../interpreter/limits.js"
 import { invalidData, IteratorSymbol, rangeError, typeError } from "../interpreter/model.js"
-import { define, get, hidden, Arr, GeneratorObj, IteratorObj, Obj } from "../interpreter/objects.js"
+import {
+  define,
+  get,
+  hidden,
+  Arr,
+  GeneratorObj,
+  hostIterator,
+  Obj,
+  PromiseObj,
+  coerceToInteger,
+  coerceToNumber,
+  coerceToString,
+  type Value,
+} from "../interpreter/objects.js"
 import { describeValue, rejectCircularInsertion } from "../interpreter/references.js"
-import { applyCollectionCallback, preserveConsumerError } from "../interpreter/callback.js"
+import { applyCollectionCallback, invoke, preserveConsumerError } from "../interpreter/callback.js"
 import type { Interpreter } from "../interpreter/interpreter.js"
 import { compareText } from "../tool-runtime.js"
-import { coerceToNumber, coerceToString } from "./value.js"

-const arrayLikeSource = (source: unknown): { readonly length: number; readonly source: Obj } => {
-  if (source instanceof Obj && typeof get(source, "length") === "number") {
-    const length = get(source, "length") as number
-    const normalized = Number.isNaN(length) || length <= 0 ? 0 : Math.trunc(length)
-    checkArrayLength(normalized)
-    return { length: normalized, source }
+const arrayLikeSource = (source: Value): { readonly length: number; readonly source: Obj } => {
+  // JS would treat a promise as an empty array-like; that would hide a missing `await`.
+  if (source instanceof Obj && !(source instanceof PromiseObj)) {
+    const length = Math.max(0, coerceToInteger(get(source, "length")))
+    checkArrayLength(length)
+    return { length, source }
  }
-  throw invalidData(
-    `Array.from expects an array, string, Map, Set, or array-like value, received ${describeValue(source)}.`,
-  )
+  throw invalidData(`Array.from expects an iterable or array-like value, received ${describeValue(source)}.`)
 }

-const arrayFrom = <R>(ctx: Interpreter<R>, args: Array<unknown>): Effect.Effect<unknown, unknown, R> => {
+const arrayFrom = <R>(ctx: Interpreter<R>, args: Array<Value>): Effect.Effect<Value, unknown, R> => {
  const source = args[0]
  const proto = ctx.builtins.Array
  const apply =
@@ -30,22 +40,26 @@ const arrayFrom = <R>(ctx: Interpreter<R>, args: Array<unknown>): Effect.Effect<
    const cursor = yield* ctx.iterate(source)
    if (cursor === undefined) {
      if (source instanceof GeneratorObj) {
-        throw typeError("Array.from expects a synchronous iterable or array-like value.")
+        throw typeError(
+          `Array.from expects a synchronous iterable or array-like value, received ${describeValue(source)}.`,
+        )
      }
      const arrayLike = arrayLikeSource(source)
-      const values: Array<unknown> = []
+      const values: Array<Value> = []
      for (let index = 0; index < arrayLike.length; index += 1) {
        const item = get(arrayLike.source, index)
        values.push(apply === undefined ? item : yield* apply([item, index]))
      }
      return new Arr(proto, values)
    }
-    const values: Array<unknown> = []
+    const values: Array<Value> = []
    let index = 0
    while (true) {
      const step = yield* cursor.next
      if (step.done) return new Arr(proto, values)
-      values.push(apply === undefined ? step.value : yield* preserveConsumerError(cursor, apply([step.value, index])))
+      values.push(
+        apply === undefined ? step.value : yield* preserveConsumerError(cursor.close, apply([step.value, index])),
+      )
      index += 1
    }
  })
@@ -53,21 +67,21 @@ const arrayFrom = <R>(ctx: Interpreter<R>, args: Array<unknown>): Effect.Effect<

 export const sortArray = <R>(
  ctx: Interpreter<R>,
-  target: Array<unknown>,
-  comparator: unknown,
+  target: Array<Value>,
+  comparator: Value,
  name: string,
-): Effect.Effect<Array<unknown>, unknown, R> => {
+): Effect.Effect<Array<Value>, unknown, R> => {
  if (comparator === undefined) {
    return Effect.sync(() => [...target].sort((a, b) => compareText(coerceToString(a), coerceToString(b))))
  }
  const apply = applyCollectionCallback(ctx, comparator, name)
-  const mergeSort = (items: Array<unknown>): Effect.Effect<Array<unknown>, unknown, R> => {
+  const mergeSort = (items: Array<Value>): Effect.Effect<Array<Value>, unknown, R> => {
    if (items.length <= 1) return Effect.succeed(items)
    const midpoint = Math.floor(items.length / 2)
    return Effect.gen(function* () {
      const left = yield* mergeSort(items.slice(0, midpoint))
      const right = yield* mergeSort(items.slice(midpoint))
-      const merged: Array<unknown> = []
+      const merged: Array<Value> = []
      let leftIndex = 0
      let rightIndex = 0
      while (leftIndex < left.length && rightIndex < right.length) {
@@ -88,8 +102,8 @@ export const sortArray = <R>(
 export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
  const builtins = ctx.builtins
  const proto = builtins.Array
-  const wrap = (items: Array<unknown>) => new Arr(proto, items)
-  const construct = (args: Array<unknown>, into: Obj): Arr => {
+  const wrap = (items: Array<Value>) => new Arr(proto, items)
+  const construct = (args: Array<Value>, into: Obj): Arr => {
    if (args.length !== 1) return new Arr(into, [...args])
    const first = args[0]
    if (typeof first !== "number") return new Arr(into, [first])
@@ -109,24 +123,18 @@ export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
    ["from", 1, (_, args) => arrayFrom(ctx, args)],
  ])

-  const self = (thisValue: unknown, name: string) => receiver(Arr, thisValue, `Array.prototype.${name}`)
-  const optNumber = (name: string, value: unknown, label: string): number | undefined => {
-    if (value === undefined) return undefined
-    if (typeof value !== "number") {
-      throw typeError(`Array.${name} expects ${label} to be a number.`)
-    }
-    return value
-  }
+  const self = (thisValue: Value, name: string) => receiver(Arr, thisValue, `Array.prototype.${name}`)
+  const optNumber = (value: Value): number | undefined => (value === undefined ? undefined : coerceToInteger(value))
  // Callback methods fix the iteration length while reading existing elements live.
  const iterate = (
    name: string,
    length: number,
    body: (
-      target: Array<unknown>,
+      target: Array<Value>,
      receiver: Arr,
-      apply: (args: Array<unknown>) => Effect.Effect<unknown, unknown, R>,
-      args: Array<unknown>,
-    ) => Effect.Effect<unknown, unknown, R>,
+      apply: (args: Array<Value>) => Effect.Effect<Value, unknown, R>,
+      args: Array<Value>,
+    ) => Effect.Effect<Value, unknown, R>,
  ): Method => [
    name,
    length,
@@ -141,13 +149,9 @@ export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
      "join",
      1,
      (thisValue, args) => {
-        const target = self(thisValue, "join").items
-        if (args.length > 1 || (args.length === 1 && typeof args[0] !== "string")) {
-          throw typeError("Array.join expects zero arguments or one string separator.")
-        }
-        const joined = target
-          .map((item) => coerceToString(item ?? ""))
-          .join(args.length === 0 ? "," : (args[0] as string))
+        const joined = self(thisValue, "join")
+          .items.map((item) => coerceToString(item ?? ""))
+          .join(args[0] === undefined ? "," : coerceToString(args[0]))
        checkStringLength(joined.length)
        return joined
      },
@@ -164,40 +168,23 @@ export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
      "includes",
      1,
      (thisValue, args) => {
-        const target = self(thisValue, "includes").items
-        if (args.length === 0 || args.length > 2) {
-          throw typeError("Array.includes expects a value and optional start index.")
-        }
-        return target.includes(args[0], optNumber("includes", args[1], "start index"))
+        return self(thisValue, "includes").items.includes(args[0], optNumber(args[1]))
      },
    ],
-    [
-      "indexOf",
-      1,
-      (thisValue, args) =>
-        self(thisValue, "indexOf").items.indexOf(args[0], optNumber("indexOf", args[1], "start index")),
-    ],
+    ["indexOf", 1, (thisValue, args) => self(thisValue, "indexOf").items.indexOf(args[0], optNumber(args[1]))],
    [
      "lastIndexOf",
      1,
      (thisValue, args) => {
        const target = self(thisValue, "lastIndexOf").items
-        return args[1] === undefined
-          ? target.lastIndexOf(args[0])
-          : target.lastIndexOf(args[0], optNumber("lastIndexOf", args[1], "start index"))
+        return args[1] === undefined ? target.lastIndexOf(args[0]) : target.lastIndexOf(args[0], optNumber(args[1]))
      },
    ],
-    ["at", 1, (thisValue, args) => self(thisValue, "at").items.at(optNumber("at", args[0], "index") ?? 0)],
+    ["at", 1, (thisValue, args) => self(thisValue, "at").items.at(optNumber(args[0]) ?? 0)],
    [
      "slice",
      2,
-      (thisValue, args) =>
-        wrap(
-          self(thisValue, "slice").items.slice(
-            optNumber("slice", args[0], "start"),
-            optNumber("slice", args[1], "end"),
-          ),
-        ),
+      (thisValue, args) => wrap(self(thisValue, "slice").items.slice(optNumber(args[0]), optNumber(args[1]))),
    ],
    [
      "concat",
@@ -214,9 +201,9 @@ export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
      "flat",
      0,
      (thisValue, args) => {
-        const flatten = (items: Array<unknown>, depth: number): Array<unknown> =>
+        const flatten = (items: Array<Value>, depth: number): Array<Value> =>
          items.flatMap((item) => (item instanceof Arr && depth > 0 ? flatten(item.items, depth - 1) : [item]))
-        const flattened = flatten(self(thisValue, "flat").items, optNumber("flat", args[0], "depth") ?? 1)
+        const flattened = flatten(self(thisValue, "flat").items, optNumber(args[0]) ?? 1)
        checkArrayLength(flattened.length)
        return wrap(flattened)
      },
@@ -262,7 +249,7 @@ export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
      2,
      (thisValue, args) => {
        const target = self(thisValue, "with").items
-        const index = optNumber("with", args[0], "index") ?? 0
+        const index = optNumber(args[0]) ?? 0
        const resolved = index < 0 ? target.length + index : index
        if (resolved < 0 || resolved >= target.length) throw rangeError("Array.with index is out of range.")
        const copied = [...target]
@@ -297,9 +284,9 @@ export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
      (thisValue, args) => {
        const target = self(thisValue, "splice")
        if (args.length === 0) return wrap(target.items.splice(0, 0))
-        const start = optNumber("splice", args[0], "start") ?? 0
+        const start = optNumber(args[0]) ?? 0
        if (args.length === 1) return wrap(target.items.splice(start))
-        const deleteCount = optNumber("splice", args[1], "delete count") ?? 0
+        const deleteCount = optNumber(args[1]) ?? 0
        const inserted = args.slice(2)
        for (const item of inserted) rejectCircularInsertion(target, item, "Array.splice result")
        return wrap(target.items.splice(start, deleteCount, ...inserted))
@@ -311,9 +298,9 @@ export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
      (thisValue, args) => {
        const copied = [...self(thisValue, "toSpliced").items]
        if (args.length === 0) return wrap(copied)
-        const start = optNumber("toSpliced", args[0], "start") ?? 0
+        const start = optNumber(args[0]) ?? 0
        if (args.length === 1) copied.splice(start)
-        else copied.splice(start, optNumber("toSpliced", args[1], "delete count") ?? 0, ...args.slice(2))
+        else copied.splice(start, optNumber(args[1]) ?? 0, ...args.slice(2))
        return wrap(copied)
      },
    ],
@@ -323,7 +310,7 @@ export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
      (thisValue, args) => {
        const target = self(thisValue, "fill")
        rejectCircularInsertion(target, args[0], "Array.fill result")
-        target.items.fill(args[0], optNumber("fill", args[1], "start"), optNumber("fill", args[2], "end"))
+        target.items.fill(args[0], optNumber(args[1]), optNumber(args[2]))
        return target
      },
    ],
@@ -332,22 +319,31 @@ export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
      2,
      (thisValue, args) => {
        const target = self(thisValue, "copyWithin")
-        target.items.copyWithin(
-          optNumber("copyWithin", args[0], "target index") ?? 0,
-          optNumber("copyWithin", args[1], "start") ?? 0,
-          optNumber("copyWithin", args[2], "end"),
-        )
+        target.items.copyWithin(optNumber(args[0]) ?? 0, optNumber(args[1]) ?? 0, optNumber(args[2]))
        return target
      },
    ],
-    ["keys", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "keys").items.keys())],
-    ["values", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "values").items.values())],
+    [
+      "toLocaleString",
+      0,
+      (thisValue) =>
+        Effect.map(
+          Effect.forEach(self(thisValue, "toLocaleString").items, (item) =>
+            item === null || item === undefined
+              ? Effect.succeed("")
+              : Effect.map(invoke(ctx, item, "toLocaleString", "Array.prototype.toLocaleString"), coerceToString),
+          ),
+          (parts) => parts.join(","),
+        ),
+    ],
+    ["keys", 0, (thisValue) => hostIterator(builtins, self(thisValue, "keys").items.keys())],
+    ["values", 0, (thisValue) => hostIterator(builtins, self(thisValue, "values").items.values())],
    [
      "entries",
      0,
      (thisValue) =>
-        new IteratorObj(
-          builtins.Iterator,
+        hostIterator(
+          builtins,
          self(thisValue, "entries")
            .items.entries()
            .map(([index, item]) => wrap([index, item])),
@@ -356,7 +352,7 @@ export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
    iterate("map", 1, (target, receiver, apply) =>
      Effect.gen(function* () {
        const length = target.length
-        const values: Array<unknown> = []
+        const values: Array<Value> = []
        values.length = length
        for (let index = 0; index < length; index += 1) {
          if (!(index in target)) continue
@@ -368,7 +364,7 @@ export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
    iterate("flatMap", 1, (target, receiver, apply) =>
      Effect.gen(function* () {
        const length = target.length
-        const values: Array<unknown> = []
+        const values: Array<Value> = []
        for (let index = 0; index < length; index += 1) {
          if (!(index in target)) continue
          const mapped = yield* apply([target[index], index, receiver])
@@ -381,7 +377,7 @@ export const arrayGlobal = <R>(ctx: Interpreter<R>) => {
    iterate("filter", 1, (target, receiver, apply) =>
      Effect.gen(function* () {
        const length = target.length
-        const values: Array<unknown> = []
+        const values: Array<Value> = []
        for (let index = 0; index < length; index += 1) {
          if (!(index in target)) continue
          const item = target[index]
@@ -2,13 +2,25 @@ import { Effect } from "effect"
 import { checkArrayLength, checkStringLength } from "../interpreter/limits.js"
 import { constructor, methods, prototypeFrom, receiver, requiresNew } from "../interpreter/native.js"
 import { IteratorSymbol, rangeError, syntaxError, typeError } from "../interpreter/model.js"
-import { define, defineAccessor, get, hidden, Arr, Bytes, IteratorObj, Obj } from "../interpreter/objects.js"
+import {
+  define,
+  defineAccessor,
+  get,
+  hidden,
+  Arr,
+  Bytes,
+  hostIterator,
+  Obj,
+  coerceToInteger,
+  coerceToNumber,
+  coerceToString,
+  type Value,
+} from "../interpreter/objects.js"
 import { describeValue } from "../interpreter/references.js"
 import type { Interpreter } from "../interpreter/interpreter.js"
-import { coerceToNumber, coerceToString } from "./value.js"

 /** The bytes a Uint8Array, array, or other iterable of numbers describes; the host array clamps each value. */
-const collectBytes = <R>(ctx: Interpreter<R>, source: unknown, name: string): Effect.Effect<Uint8Array, unknown, R> => {
+const collectBytes = <R>(ctx: Interpreter<R>, source: Value, name: string): Effect.Effect<Uint8Array, unknown, R> => {
  if (source instanceof Bytes) return Effect.succeed(new Uint8Array(source.bytes))
  return Effect.gen(function* () {
    const cursor = yield* ctx.iterate(source)
@@ -27,7 +39,7 @@ const collectBytes = <R>(ctx: Interpreter<R>, source: unknown, name: string): Ef
  })
 }

-const constructBytes = <R>(ctx: Interpreter<R>, args: Array<unknown>, proto: Obj) => {
+const constructBytes = <R>(ctx: Interpreter<R>, args: Array<Value>, proto: Obj) => {
  const source = args[0]
  if (source !== null && typeof source === "object") {
    return Effect.map(collectBytes(ctx, source, "new Uint8Array(...)"), (bytes) => new Bytes(proto, bytes))
@@ -48,7 +60,7 @@ export const uint8ArrayGlobal = <R>(ctx: Interpreter<R>) => {
    call: requiresNew("Uint8Array"),
    construct: (args, newTarget) => constructBytes(ctx, args, prototypeFrom(newTarget, proto)),
  })
-  const decode = (name: string, args: Array<unknown>, from: (text: string) => Uint8Array) => {
+  const decode = (name: string, args: Array<Value>, from: (text: string) => Uint8Array) => {
    if (typeof args[0] !== "string") throw typeError(`Uint8Array.${name} expects a string.`)
    try {
      return wrap(from(args[0]))
@@ -63,45 +75,29 @@ export const uint8ArrayGlobal = <R>(ctx: Interpreter<R>) => {
    ["fromHex", 1, (_, args) => decode("fromHex", args, (text) => Uint8Array.fromHex(text))],
  ])

-  const self = (thisValue: unknown, name: string) => receiver(Bytes, thisValue, `Uint8Array.prototype.${name}`)
-  const optNumber = (name: string, value: unknown, label: string): number | undefined => {
-    if (value === undefined) return undefined
-    if (typeof value !== "number") throw typeError(`Uint8Array.${name} expects ${label} to be a number.`)
-    return value
-  }
-  const wrapAll = (items: Array<unknown>) => new Arr(builtins.Array, items)
+  const self = (thisValue: Value, name: string) => receiver(Bytes, thisValue, `Uint8Array.prototype.${name}`)
+  const optNumber = (value: Value): number | undefined => (value === undefined ? undefined : coerceToInteger(value))
+  const wrapAll = (items: Array<Value>) => new Arr(builtins.Array, items)
  defineAccessor(proto, "length", (thisValue) => self(thisValue, "length").bytes.length)
  methods(builtins, proto, [
-    ["at", 1, (thisValue, args) => self(thisValue, "at").bytes.at(optNumber("at", args[0], "index") ?? 0)],
+    ["at", 1, (thisValue, args) => self(thisValue, "at").bytes.at(optNumber(args[0]) ?? 0)],
    [
      "slice",
      2,
-      (thisValue, args) =>
-        wrap(
-          self(thisValue, "slice").bytes.slice(
-            optNumber("slice", args[0], "start"),
-            optNumber("slice", args[1], "end"),
-          ),
-        ),
+      (thisValue, args) => wrap(self(thisValue, "slice").bytes.slice(optNumber(args[0]), optNumber(args[1]))),
    ],
    // A view on the same bytes, as in JS: writes through one are visible through the other.
    [
      "subarray",
      2,
-      (thisValue, args) =>
-        wrap(
-          self(thisValue, "subarray").bytes.subarray(
-            optNumber("subarray", args[0], "start"),
-            optNumber("subarray", args[1], "end"),
-          ),
-        ),
+      (thisValue, args) => wrap(self(thisValue, "subarray").bytes.subarray(optNumber(args[0]), optNumber(args[1]))),
    ],
    [
      "set",
      1,
      (thisValue, args) => {
        const target = self(thisValue, "set")
-        const offset = optNumber("set", args[1], "offset") ?? 0
+        const offset = optNumber(args[1]) ?? 0
        return Effect.map(collectBytes(ctx, args[0], "Uint8Array.set"), (source) => {
          if (!Number.isInteger(offset) || offset < 0 || source.length + offset > target.bytes.length) {
            throw rangeError("Uint8Array.set: the source does not fit at that offset.")
@@ -116,11 +112,7 @@ export const uint8ArrayGlobal = <R>(ctx: Interpreter<R>) => {
      1,
      (thisValue, args) => {
        const target = self(thisValue, "fill")
-        target.bytes.fill(
-          coerceToNumber(args[0]),
-          optNumber("fill", args[1], "start"),
-          optNumber("fill", args[2], "end"),
-        )
+        target.bytes.fill(coerceToNumber(args[0]), optNumber(args[1]), optNumber(args[2]))
        return target
      },
    ],
@@ -136,8 +128,7 @@ export const uint8ArrayGlobal = <R>(ctx: Interpreter<R>) => {
    [
      "indexOf",
      1,
-      (thisValue, args) =>
-        self(thisValue, "indexOf").bytes.indexOf(coerceToNumber(args[0]), optNumber("indexOf", args[1], "start index")),
+      (thisValue, args) => self(thisValue, "indexOf").bytes.indexOf(coerceToNumber(args[0]), optNumber(args[1])),
    ],
    [
      "lastIndexOf",
@@ -146,26 +137,19 @@ export const uint8ArrayGlobal = <R>(ctx: Interpreter<R>) => {
        const target = self(thisValue, "lastIndexOf").bytes
        return args[1] === undefined
          ? target.lastIndexOf(coerceToNumber(args[0]))
-          : target.lastIndexOf(coerceToNumber(args[0]), optNumber("lastIndexOf", args[1], "start index"))
+          : target.lastIndexOf(coerceToNumber(args[0]), optNumber(args[1]))
      },
    ],
    [
      "includes",
      1,
-      (thisValue, args) =>
-        self(thisValue, "includes").bytes.includes(
-          coerceToNumber(args[0]),
-          optNumber("includes", args[1], "start index"),
-        ),
+      (thisValue, args) => self(thisValue, "includes").bytes.includes(coerceToNumber(args[0]), optNumber(args[1])),
    ],
    [
      "join",
      1,
      (thisValue, args) => {
-        if (args.length > 1 || (args.length === 1 && typeof args[0] !== "string")) {
-          throw typeError("Uint8Array.join expects zero arguments or one string separator.")
-        }
-        const joined = self(thisValue, "join").bytes.join(args.length === 0 ? "," : (args[0] as string))
+        const joined = self(thisValue, "join").bytes.join(args[0] === undefined ? "," : coerceToString(args[0]))
        checkStringLength(joined.length)
        return joined
      },
@@ -173,14 +157,14 @@ export const uint8ArrayGlobal = <R>(ctx: Interpreter<R>) => {
    ["toString", 0, (thisValue) => self(thisValue, "toString").bytes.join(",")],
    ["toBase64", 0, (thisValue) => self(thisValue, "toBase64").bytes.toBase64()],
    ["toHex", 0, (thisValue) => self(thisValue, "toHex").bytes.toHex()],
-    ["keys", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "keys").bytes.keys())],
-    ["values", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "values").bytes.values())],
+    ["keys", 0, (thisValue) => hostIterator(builtins, self(thisValue, "keys").bytes.keys())],
+    ["values", 0, (thisValue) => hostIterator(builtins, self(thisValue, "values").bytes.values())],
    [
      "entries",
      0,
      (thisValue) =>
-        new IteratorObj(
-          builtins.Iterator,
+        hostIterator(
+          builtins,
          self(thisValue, "entries")
            .bytes.entries()
            .map(([index, byte]) => wrapAll([index, byte])),
@@ -222,8 +206,7 @@ const utf8Labels = new Set(["unicode-1-1-utf-8", "unicode11utf8", "unicode20utf8
 export const textDecoderGlobal = <R>(ctx: Interpreter<R>) => {
  const builtins = ctx.builtins
  const proto = builtins.TextDecoder
-  const self = (thisValue: unknown, name: string) =>
-    receiver(TextDecoderObj, thisValue, `TextDecoder.prototype.${name}`)
+  const self = (thisValue: Value, name: string) => receiver(TextDecoderObj, thisValue, `TextDecoder.prototype.${name}`)
  defineAccessor(proto, "encoding", (thisValue) => self(thisValue, "encoding").decoder.encoding)
  defineAccessor(proto, "fatal", (thisValue) => self(thisValue, "fatal").decoder.fatal)
  defineAccessor(proto, "ignoreBOM", (thisValue) => self(thisValue, "ignoreBOM").decoder.ignoreBOM)
@@ -7,15 +7,17 @@ import {
  get,
  getOwn,
  hidden,
-  isWrapper,
  Arr,
-  IteratorObj,
+  coerceToString,
+  hostCursor,
+  hostIterator,
  MapObj,
  Obj,
  PromiseObj,
  SetObj,
+  type Value,
 } from "../interpreter/objects.js"
-import { describeValue, isRuntimeReference } from "../interpreter/references.js"
+import { describeValue, isOpaque } from "../interpreter/references.js"
 import {
  applyCollectionCallback,
  isSupportedCallback,
@@ -25,9 +27,9 @@ import {
 } from "../interpreter/callback.js"
 import type { Interpreter } from "../interpreter/interpreter.js"

-const coerceGroupByPropertyKey = <R>(ctx: Interpreter<R>, value: unknown): Effect.Effect<string, unknown, R> => {
-  if (value instanceof PromiseObj) return Effect.succeed("[object Promise]")
-  if (!isWrapper(value) && isRuntimeReference(value)) {
+const coerceGroupByPropertyKey = <R>(ctx: Interpreter<R>, value: Value): Effect.Effect<string, unknown, R> => {
+  if (value instanceof PromiseObj) return Effect.succeed(coerceToString(value))
+  if (isOpaque(value)) {
    throw invalidData(`Object.groupBy callback must return a data value, received ${describeValue(value)}.`)
  }
  return toPrimitiveString(ctx, value)
@@ -54,7 +56,7 @@ export const groupBy = <R>(ctx: Interpreter<R>, namespace: "Map" | "Object") =>
          const step = yield* cursor.next
          if (step.done) return result
          const item = step.value
-          const key = yield* preserveConsumerError(cursor, apply([item, index]))
+          const key = yield* preserveConsumerError(cursor.close, apply([item, index]))
          const group = result.map.get(key)
          if (group === undefined) result.map.set(key, new Arr(builtins.Array, [item]))
          else (group as Arr).items.push(item)
@@ -70,7 +72,7 @@ export const groupBy = <R>(ctx: Interpreter<R>, namespace: "Map" | "Object") =>
        if (step.done) return result
        const item = step.value
        const key = yield* preserveConsumerError(
-          cursor,
+          cursor.close,
          Effect.flatMap(apply([item, index]), (value) => coerceGroupByPropertyKey(ctx, value)),
        )
        const group = getOwn(result, key)
@@ -81,19 +83,19 @@ export const groupBy = <R>(ctx: Interpreter<R>, namespace: "Map" | "Object") =>
    })
  })

-const constructMap = <R>(ctx: Interpreter<R>, init: unknown, proto: Obj) => {
+const constructMap = <R>(ctx: Interpreter<R>, init: Value, proto: Obj) => {
  const target = new MapObj(proto)
  if (init === undefined || init === null) return Effect.succeed(target)
  return Effect.gen(function* () {
    const cursor = yield* ctx.iterate(init)
    if (cursor === undefined) {
-      throw typeError("new Map(...) expects an iterable of [key, value] pairs or no argument.")
+      throw typeError(`new Map(...) expects an iterable of [key, value] pairs, received ${describeValue(init)}.`)
    }
    while (true) {
      const step = yield* cursor.next
      if (step.done) return target
      yield* preserveConsumerError(
-        cursor,
+        cursor.close,
        Effect.sync(() => {
          if (!(step.value instanceof Obj)) {
            throw typeError("new Map(...) expects [key, value] pairs as entry objects.")
@@ -105,13 +107,13 @@ const constructMap = <R>(ctx: Interpreter<R>, init: unknown, proto: Obj) => {
  })
 }

-const constructSet = <R>(ctx: Interpreter<R>, init: unknown, proto: Obj) => {
+const constructSet = <R>(ctx: Interpreter<R>, init: Value, proto: Obj) => {
  const target = new SetObj(proto)
  if (init === undefined || init === null) return Effect.succeed(target)
  return Effect.gen(function* () {
    const cursor = yield* ctx.iterate(init)
    if (cursor === undefined) {
-      throw typeError("new Set(...) expects a synchronous iterable or no argument.")
+      throw typeError(`new Set(...) expects a synchronous iterable, received ${describeValue(init)}.`)
    }
    while (true) {
      const step = yield* cursor.next
@@ -130,8 +132,7 @@ export const mapGlobal = <R>(ctx: Interpreter<R>) => {
    construct: (args, newTarget) => constructMap(ctx, args[0], prototypeFrom(newTarget, proto)),
  })
  define(map, "groupBy", groupBy(ctx, "Map"), hidden)
-  const self = (thisValue: unknown, name: string) => receiver(MapObj, thisValue, `Map.prototype.${name}`)
-  const wrap = (items: Array<unknown>) => new Arr(builtins.Array, items)
+  const self = (thisValue: Value, name: string) => receiver(MapObj, thisValue, `Map.prototype.${name}`)
  defineAccessor(proto, "size", (thisValue) => receiver(MapObj, thisValue, "Map.prototype.size").map.size)
  methods(builtins, proto, [
    ["get", 1, (thisValue, args) => self(thisValue, "get").map.get(args[0])],
@@ -145,6 +146,29 @@ export const mapGlobal = <R>(ctx: Interpreter<R>) => {
        return target
      },
    ],
+    [
+      "getOrInsert",
+      2,
+      (thisValue, args) => {
+        const target = self(thisValue, "getOrInsert").map
+        if (!target.has(args[0])) target.set(args[0], args[1])
+        return target.get(args[0])
+      },
+    ],
+    [
+      "getOrInsertComputed",
+      2,
+      (thisValue, args) => {
+        const target = self(thisValue, "getOrInsertComputed").map
+        const apply = applyCollectionCallback(ctx, args[1], "Map.getOrInsertComputed")
+        if (target.has(args[0])) return target.get(args[0])
+        // The callback sees the stored key (-0 is +0) and its result wins over anything it inserted itself.
+        return Effect.map(apply([args[0] === 0 ? 0 : args[0]]), (value) => {
+          target.set(args[0], value)
+          return value
+        })
+      },
+    ],
    ["delete", 1, (thisValue, args) => self(thisValue, "delete").map.delete(args[0])],
    [
      "clear",
@@ -154,19 +178,9 @@ export const mapGlobal = <R>(ctx: Interpreter<R>) => {
        return undefined
      },
    ],
-    ["keys", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "keys").map.keys())],
-    ["values", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "values").map.values())],
-    [
-      "entries",
-      0,
-      (thisValue) =>
-        new IteratorObj(
-          builtins.Iterator,
-          self(thisValue, "entries")
-            .map.entries()
-            .map(([key, item]) => wrap([key, item])),
-        ),
-    ],
+    ["keys", 0, (thisValue) => hostIterator(builtins, self(thisValue, "keys").map.keys())],
+    ["values", 0, (thisValue) => hostIterator(builtins, self(thisValue, "values").map.values())],
+    ["entries", 0, (thisValue) => hostIterator(builtins, self(thisValue, "entries").iterator(builtins))],
    [
      "forEach",
      1,
@@ -174,7 +188,7 @@ export const mapGlobal = <R>(ctx: Interpreter<R>) => {
        const target = self(thisValue, "forEach")
        const apply = applyCollectionCallback(ctx, args[0], "Map.forEach")
        return Effect.gen(function* () {
-          for (const [key, item] of Array.from(target.map.entries())) yield* apply([item, key, target])
+          for (const [key, item] of target.map.entries()) yield* apply([item, key, target])
          return undefined
        })
      },
@@ -186,26 +200,26 @@ export const mapGlobal = <R>(ctx: Interpreter<R>) => {

 type SetRecord<R> = {
  readonly size: number
-  readonly has: (item: unknown) => Effect.Effect<boolean, unknown, R>
-  readonly keys: () => Effect.Effect<Iterable<unknown>, unknown, R>
+  readonly has: (item: Value) => Effect.Effect<boolean, unknown, R>
+  readonly keys: () => Effect.Effect<Iterable<Value>, unknown, R>
 }

 const loadSetRecord = <R>(
  ctx: Interpreter<R>,
-  source: unknown,
+  source: Value,
  name: string,
 ): Effect.Effect<SetRecord<R>, unknown, R> => {
  if (source instanceof SetObj) {
    return Effect.succeed({
      size: source.set.size,
-      has: (item: unknown) => Effect.succeed(source.set.has(item)),
+      has: (item: Value) => Effect.succeed(source.set.has(item)),
      keys: () => Effect.succeed(source.set.values()),
    })
  }
  if (source instanceof MapObj) {
    return Effect.succeed({
      size: source.map.size,
-      has: (item: unknown) => Effect.succeed(source.map.has(item)),
+      has: (item: Value) => Effect.succeed(source.map.has(item)),
      keys: () => Effect.succeed(source.map.keys()),
    })
  }
@@ -224,12 +238,17 @@ const loadSetRecord = <R>(
    }
    return {
      size: Math.max(Math.trunc(size), 0),
-      has: (item: unknown) => Effect.map(ctx.call(has, source, [item]), Boolean),
+      has: (item: Value) => Effect.map(ctx.call(has, source, [item]), Boolean),
      keys: () =>
-        Effect.flatMap(ctx.call(keys, source, []), (result): Effect.Effect<Iterable<unknown>> => {
-          if (result instanceof IteratorObj) return Effect.succeed(result.iterator)
-          if (result instanceof Arr) return Effect.succeed(result.items)
-          throw typeError(`Set.${name} expected 'keys' to return an iterator.`)
+        Effect.gen(function* () {
+          const result = yield* ctx.call(keys, source, [])
+          const cursor = result instanceof Arr ? hostCursor(result.items.values()) : ctx.iterateDirect(result)
+          const items: Array<Value> = []
+          while (true) {
+            const step = yield* cursor.next
+            if (step.done) return items
+            items.push(step.value)
+          }
        }),
    }
  })
@@ -239,8 +258,8 @@ const setOperation = <R>(
  ctx: Interpreter<R>,
  target: SetObj,
  name: string,
-  source: unknown,
-): Effect.Effect<unknown, unknown, R> =>
+  source: Value,
+): Effect.Effect<Value, unknown, R> =>
  Effect.gen(function* () {
    const other = yield* loadSetRecord(ctx, source, name)
    const copy = () => {
@@ -319,8 +338,8 @@ export const setGlobal = <R>(ctx: Interpreter<R>) => {
    call: requiresNew("Set"),
    construct: (args, newTarget) => constructSet(ctx, args[0], prototypeFrom(newTarget, proto)),
  })
-  const self = (thisValue: unknown, name: string) => receiver(SetObj, thisValue, `Set.prototype.${name}`)
-  const wrap = (items: Array<unknown>) => new Arr(builtins.Array, items)
+  const self = (thisValue: Value, name: string) => receiver(SetObj, thisValue, `Set.prototype.${name}`)
+  const wrap = (items: Array<Value>) => new Arr(builtins.Array, items)
  const operation = (name: string): Method => [
    name,
    1,
@@ -347,14 +366,14 @@ export const setGlobal = <R>(ctx: Interpreter<R>) => {
        return undefined
      },
    ],
-    ["keys", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "keys").set.values())],
-    ["values", 0, (thisValue) => new IteratorObj(builtins.Iterator, self(thisValue, "values").set.values())],
+    ["keys", 0, (thisValue) => hostIterator(builtins, self(thisValue, "keys").set.values())],
+    ["values", 0, (thisValue) => hostIterator(builtins, self(thisValue, "values").set.values())],
    [
      "entries",
      0,
      (thisValue) =>
-        new IteratorObj(
-          builtins.Iterator,
+        hostIterator(
+          builtins,
          self(thisValue, "entries")
            .set.values()
            .map((item) => wrap([item, item])),
@@ -367,7 +386,7 @@ export const setGlobal = <R>(ctx: Interpreter<R>) => {
        const target = self(thisValue, "forEach")
        const apply = applyCollectionCallback(ctx, args[0], "Set.forEach")
        return Effect.gen(function* () {
-          for (const item of Array.from(target.set.values())) yield* apply([item, item, target])
+          for (const item of target.set.values()) yield* apply([item, item, target])
          return undefined
        })
      },
@@ -1,22 +1,8 @@
 import { type Method, methods } from "../interpreter/native.js"
-import {
-  entries,
-  get,
-  Arr,
-  Bytes,
-  DateObj,
-  MapObj,
-  Obj,
-  PromiseObj,
-  RegExpObj,
-  SetObj,
-  URLObj,
-  URLSearchParamsObj,
-  HeadersObj,
-} from "../interpreter/objects.js"
-import { containsOpaqueReference, isRuntimeReference } from "../interpreter/references.js"
+import { entries, get, Arr, Obj, type Value } from "../interpreter/objects.js"
+import { ToolReference } from "../tool-runtime.js"
+import { containsOpaqueReference } from "../interpreter/references.js"
 import type { Interpreter } from "../interpreter/interpreter.js"
-import { coerceToString } from "./value.js"

 const consoleMethods = ["log", "info", "debug", "warn", "error", "dir", "table"]

@@ -43,7 +29,7 @@ export const consoleGlobal = <R>(ctx: Interpreter<R>) => {

 const MAX_CONSOLE_DEPTH = 32

-const formatConsoleMessage = (name: string, args: Array<unknown>): string => {
+const formatConsoleMessage = (name: string, args: Array<Value>): string => {
  if (name === "dir") return args.length === 0 ? "undefined" : formatValue(args[0])
  if (name === "table") return formatConsoleTable(args[0], args[1])
  const prefix = name === "warn" ? "[warn] " : name === "error" ? "[error] " : name === "debug" ? "[debug] " : ""
@@ -51,60 +37,27 @@ const formatConsoleMessage = (name: string, args: Array<unknown>): string => {
 }

 /** One value as `console.log` shows it. */
-export const formatValue = (value: unknown): string => {
+export const formatValue = (value: Value): string => {
  if (value === undefined) return "undefined"
  if (typeof value === "string") return value
  return formatConsoleValue(value, new Set(), 0)
 }

-const formatConsoleValue = (value: unknown, seen: Set<object>, depth: number): string => {
+const formatConsoleValue = (value: Value, seen: Set<object>, depth: number): string => {
  if (value === null || value === undefined) return "null"
  if (typeof value === "string") return JSON.stringify(value)
-  if (typeof value === "number" || typeof value === "boolean") return String(value)
-  if (typeof value !== "object") return String(value)
-  if (value instanceof PromiseObj) return "[Promise (await it to get its value)]"
-  if (value instanceof DateObj) return coerceToString(value)
-  if (value instanceof RegExpObj) return coerceToString(value)
-  if (value instanceof URLObj) return coerceToString(value)
-  if (value instanceof URLSearchParamsObj) return coerceToString(value)
-  if (value instanceof HeadersObj) return `Headers ${JSON.stringify(Object.fromEntries(value.headers))}`
-  if (value instanceof Bytes) return `Uint8Array(${value.bytes.length}) [${value.bytes.join(",")}]`
+  if (!(value instanceof Obj)) return value instanceof ToolReference ? "[opaque reference]" : String(value)
  if (depth > MAX_CONSOLE_DEPTH) return "..."
  if (seen.has(value)) return "[Circular]"
-  if (value instanceof MapObj) {
-    seen.add(value)
-    try {
-      const items = Array.from(value.map.entries(), ([key, item]) => `[${formatItems([key, item], seen, depth + 1)}]`)
-      return `Map(${value.map.size}) [${items.join(",")}]`
-    } finally {
-      seen.delete(value)
-    }
-  }
-  if (value instanceof SetObj) {
-    seen.add(value)
-    try {
-      return `Set(${value.set.size}) [${formatItems([...value.set.values()], seen, depth + 1)}]`
-    } finally {
-      seen.delete(value)
-    }
-  }
-  if (isRuntimeReference(value)) return "[opaque reference]"
  seen.add(value)
  try {
-    if (value instanceof Arr) return `[${formatItems(value.items, seen, depth + 1)}]`
-    if (!(value instanceof Obj)) return "[object Object]"
-    return `{${entries(value)
-      .map(([key, item]) => `${JSON.stringify(key)}:${formatConsoleValue(item, seen, depth + 1)}`)
-      .join(",")}}`
+    return value.inspect((item) => formatConsoleValue(item, seen, depth + 1))
  } finally {
    seen.delete(value)
  }
 }

-const formatItems = (items: Array<unknown>, seen: Set<object>, depth: number): string =>
-  items.map((item) => formatConsoleValue(item, seen, depth)).join(",")
-
-const formatConsoleTable = (value: unknown, columnsArgument: unknown): string => {
+const formatConsoleTable = (value: Value, columnsArgument: Value): string => {
  if (value === undefined) return "undefined"
  if (containsOpaqueReference(value)) return "[opaque reference]"
  const columns = columnsArgument instanceof Arr ? columnsArgument.items.map(String) : undefined
@@ -118,9 +71,9 @@ const formatConsoleTable = (value: unknown, columnsArgument: unknown): string =>
 }

 const consoleTableRows = (
-  data: unknown,
+  data: Value,
  columns: ReadonlyArray<string> | undefined,
-): Array<{ readonly index: string; readonly values: Record<string, unknown> }> => {
+): Array<{ readonly index: string; readonly values: Record<string, Value> }> => {
  if (data instanceof Arr) {
    return data.items.map((item, index) => ({ index: String(index), values: consoleTableValues(item, columns) }))
  }
@@ -130,7 +83,7 @@ const consoleTableRows = (
  return [{ index: "0", values: { Value: data } }]
 }

-const consoleTableValues = (value: unknown, columns: ReadonlyArray<string> | undefined): Record<string, unknown> => {
+const consoleTableValues = (value: Value, columns: ReadonlyArray<string> | undefined): Record<string, Value> => {
  if (value instanceof Obj && !(value instanceof Arr)) {
    if (columns !== undefined) return Object.fromEntries(columns.map((column) => [column, get(value, column)]))
    return Object.fromEntries(entries(value))
@@ -138,7 +91,7 @@ const consoleTableValues = (value: unknown, columns: ReadonlyArray<string> | und
  return { Value: value }
 }

-const formatConsoleTableCell = (value: unknown): string => {
+const formatConsoleTableCell = (value: Value): string => {
  if (value === undefined) return ""
  if (typeof value === "string") return value
  return formatConsoleValue(value, new Set(), 0)
@@ -1,12 +1,11 @@
 import { Effect } from "effect"
 import { constructor, type Method, methods, prototypeFrom, receiver } from "../interpreter/native.js"
 import { rangeError } from "../interpreter/model.js"
-import { DateObj, Obj } from "../interpreter/objects.js"
+import { DateObj, Obj, coerceToNumber, coerceToString, type Value } from "../interpreter/objects.js"
 import { toPrimitive, toPrimitiveNumber } from "../interpreter/callback.js"
 import type { Interpreter } from "../interpreter/interpreter.js"
-import { coerceToNumber, coerceToString } from "./value.js"

-const constructDate = <R>(ctx: Interpreter<R>, args: Array<unknown>, proto: Obj) => {
+const constructDate = <R>(ctx: Interpreter<R>, args: Array<Value>, proto: Obj) => {
  if (args.length === 0) return Effect.succeed(new DateObj(proto, Date.now()))
  if (args.length === 1) {
    const arg = args[0]
@@ -83,7 +82,7 @@ export const dateGlobal = <R>(ctx: Interpreter<R>) => {
    ["UTC", 7, (_, args) => Date.UTC(...(args.map((arg) => coerceToNumber(arg)) as Parameters<typeof Date.UTC>))],
  ])

-  const self = (thisValue: unknown, name: string) => receiver(DateObj, thisValue, `Date.prototype.${name}`)
+  const self = (thisValue: Value, name: string) => receiver(DateObj, thisValue, `Date.prototype.${name}`)
  const iso = (value: DateObj) => {
    if (!Number.isFinite(value.time)) throw rangeError("Invalid time value.")
    return new Date(value.time).toISOString()
@@ -105,6 +104,13 @@ export const dateGlobal = <R>(ctx: Interpreter<R>) => {
    ["toTimeString", 0, (thisValue) => new Date(self(thisValue, "toTimeString").time).toTimeString()],
    ["toUTCString", 0, (thisValue) => new Date(self(thisValue, "toUTCString").time).toUTCString()],
    ["toGMTString", 0, (thisValue) => new Date(self(thisValue, "toGMTString").time).toUTCString()],
+    ...(["toLocaleString", "toLocaleDateString", "toLocaleTimeString"] as const).map(
+      (name): Method => [
+        name,
+        0,
+        (thisValue) => new Date(self(thisValue, name).time)[name]("en-US", { timeZone: "UTC" }),
+      ],
+    ),
    ...getters.map((name): Method => [name, 0, (thisValue) => new Date(self(thisValue, name).time)[name]()]),
    ...setters.map(
      ([name, length]): Method => [
@@ -1,11 +1,21 @@
 import { Effect } from "effect"
 import { constructor, methods, prototypeFrom, receiver, requiresNew } from "../interpreter/native.js"
 import { IteratorSymbol, typeError } from "../interpreter/model.js"
-import { define, entries, get, hidden, Arr, HeadersObj, IteratorObj, Obj } from "../interpreter/objects.js"
+import {
+  define,
+  entries,
+  get,
+  hidden,
+  Arr,
+  HeadersObj,
+  hostIterator,
+  Obj,
+  coerceToString,
+  isRuntimeReference,
+  type Value,
+} from "../interpreter/objects.js"
 import { applyCollectionCallback } from "../interpreter/callback.js"
-import { isRuntimeReference } from "../interpreter/references.js"
 import type { Interpreter } from "../interpreter/interpreter.js"
-import { coerceToString } from "./value.js"
 import { readPairs } from "./url.js"

 // The host validates header names and values and throws its own TypeError; the program gets one of its own.
@@ -17,7 +27,7 @@ const attempt = <T>(run: () => T): T => {
  }
 }

-const constructHeaders = <R>(ctx: Interpreter<R>, init: unknown, proto: Obj): Effect.Effect<HeadersObj, unknown, R> => {
+const constructHeaders = <R>(ctx: Interpreter<R>, init: Value, proto: Obj): Effect.Effect<HeadersObj, unknown, R> => {
  const wrap = (headers: Headers) => new HeadersObj(proto, headers)
  if (init === undefined) return Effect.succeed(wrap(new Headers()))
  return Effect.gen(function* () {
@@ -40,10 +50,10 @@ export const headersGlobal = <R>(ctx: Interpreter<R>) => {
    call: requiresNew("Headers"),
    construct: (args, newTarget) => constructHeaders(ctx, args[0], prototypeFrom(newTarget, proto)),
  })
-  const self = (thisValue: unknown, name: string) => receiver(HeadersObj, thisValue, `Headers.prototype.${name}`)
-  const wrap = (items: Array<unknown>) => new Arr(builtins.Array, items)
-  const arg = (args: Array<unknown>, index: number): string => coerceToString(args[index])
-  const requireArgs = (name: string, args: Array<unknown>, count: number): void => {
+  const self = (thisValue: Value, name: string) => receiver(HeadersObj, thisValue, `Headers.prototype.${name}`)
+  const wrap = (items: Array<Value>) => new Arr(builtins.Array, items)
+  const arg = (args: Array<Value>, index: number): string => coerceToString(args[index])
+  const requireArgs = (name: string, args: Array<Value>, count: number): void => {
    if (args.length < count) throw typeError(`Headers.${name} requires ${count} argument${count === 1 ? "" : "s"}.`)
  }
  methods(builtins, proto, [
@@ -53,7 +63,8 @@ export const headersGlobal = <R>(ctx: Interpreter<R>) => {
      (thisValue, args) => {
        requireArgs("append", args, 2)
        const target = self(thisValue, "append").headers
-        return attempt(() => target.append(arg(args, 0), arg(args, 1)))
+        attempt(() => target.append(arg(args, 0), arg(args, 1)))
+        return undefined
      },
    ],
    [
@@ -62,7 +73,8 @@ export const headersGlobal = <R>(ctx: Interpreter<R>) => {
      (thisValue, args) => {
        requireArgs("delete", args, 1)
        const target = self(thisValue, "delete").headers
-        return attempt(() => target.delete(arg(args, 0)))
+        attempt(() => target.delete(arg(args, 0)))
+        return undefined
      },
    ],
    [
@@ -90,29 +102,13 @@ export const headersGlobal = <R>(ctx: Interpreter<R>) => {
      (thisValue, args) => {
        requireArgs("set", args, 2)
        const target = self(thisValue, "set").headers
-        return attempt(() => target.set(arg(args, 0), arg(args, 1)))
+        attempt(() => target.set(arg(args, 0), arg(args, 1)))
+        return undefined
      },
    ],
-    // Iterator.from because Bun's Headers typings predate iterator helpers; the runtime iterators already have them.
-    [
-      "keys",
-      0,
-      (thisValue) => new IteratorObj(builtins.Iterator, Iterator.from(self(thisValue, "keys").headers.keys())),
-    ],
-    [
-      "values",
-      0,
-      (thisValue) => new IteratorObj(builtins.Iterator, Iterator.from(self(thisValue, "values").headers.values())),
-    ],
-    [
-      "entries",
-      0,
-      (thisValue) =>
-        new IteratorObj(
-          builtins.Iterator,
-          Iterator.from(self(thisValue, "entries").headers.entries()).map(([key, value]) => wrap([key, value])),
-        ),
-    ],
+    ["keys", 0, (thisValue) => hostIterator(builtins, self(thisValue, "keys").headers.keys())],
+    ["values", 0, (thisValue) => hostIterator(builtins, self(thisValue, "values").headers.values())],
+    ["entries", 0, (thisValue) => hostIterator(builtins, self(thisValue, "entries").iterator(builtins))],
    [
      "forEach",
      1,
@@ -1,19 +1,348 @@
-import { methods, receiver } from "../interpreter/native.js"
-import { IteratorObj, record } from "../interpreter/objects.js"
+import { Cause, Effect, Exit } from "effect"
+import { applyCollectionCallback } from "../interpreter/callback.js"
 import type { Interpreter } from "../interpreter/interpreter.js"
+import { rangeError, typeError } from "../interpreter/model.js"
+import { constructor, fn, methods, receiver, requiresNew } from "../interpreter/native.js"
+import {
+  Arr,
+  coerceToNumber,
+  type Cursor,
+  define,
+  hasPrototype,
+  hidden,
+  IteratorObj,
+  Obj,
+  record,
+  type Step,
+  type Value,
+} from "../interpreter/objects.js"
+import { describeValue } from "../interpreter/references.js"

-// Every built-in collection iterator shares the Iterator prototype; JS gives each collection its own, which is only
+const finished: Step = { done: true, value: undefined }
+
+// Every built-in iterator and helper shares the Iterator prototype; JS gives each collection its own, which is only
 // observable through getPrototypeOf.
-export const iteratorGlobals = <R>(ctx: Interpreter<R>): void => {
+export const iteratorGlobals = <R>(ctx: Interpreter<R>) => {
  const builtins = ctx.builtins
-  methods(builtins, builtins.Iterator, [
+  const proto = builtins.Iterator
+  const method = (name: string) => `Iterator.prototype.${name}`
+
+  // A step that runs program code: when it throws, close the source first, as IteratorClose does.
+  const guarded = <A>(source: Cursor<R>, body: Effect.Effect<A, unknown, R>) =>
+    Effect.flatMap(Effect.exit(body), (exit) => {
+      if (Exit.isSuccess(exit)) return Effect.succeed(exit.value)
+      if (Cause.hasInterruptsOnly(exit.cause)) return Effect.failCause(exit.cause)
+      return Effect.andThen(Effect.exit(source.close), Effect.failCause(exit.cause))
+    })
+
+  // A lazy helper: `pull` advances it once. Once it reports done, throws, or is closed, it stays done. A callback
+  // that re-enters its own helper is a TypeError, as for a running generator.
+  const helper = (source: Cursor<R>, pull: Effect.Effect<Step, unknown, R>, close = source.close) => {
+    let done = false
+    let running = false
+    const enter = () => {
+      if (running) throw typeError("Iterator helper is already running.")
+      running = true
+    }
+    return new IteratorObj(builtins.IteratorHelper, {
+      next: Effect.suspend(() => {
+        if (done) return Effect.succeed(finished)
+        enter()
+        return Effect.flatMap(Effect.exit(pull), (exit) => {
+          running = false
+          done = Exit.isSuccess(exit) ? exit.value.done : true
+          return exit
+        })
+      }),
+      close: Effect.suspend(() => {
+        if (done) return Effect.void
+        enter()
+        done = true
+        return Effect.ensuring(
+          close,
+          Effect.sync(() => {
+            running = false
+          }),
+        )
+      }),
+    })
+  }
+
+  // GetIteratorFlattenable: an iterable by `[Symbol.iterator]`, otherwise the object itself as an iterator.
+  const flattenable = (value: Value, name: string, strings: boolean) =>
+    Effect.gen(function* () {
+      if (typeof value === "string" ? !strings : !(value instanceof Obj)) {
+        throw typeError(`${name} expects an iterable or iterator, received ${describeValue(value)}.`)
+      }
+      return (yield* ctx.iterate(value)) ?? ctx.iterateDirect(value)
+    })
+
+  const limit = (value: Value, name: string) => {
+    const count = Math.trunc(coerceToNumber(value))
+    if (Number.isNaN(count) || count < 0) {
+      throw rangeError(`${method(name)} expects a non-negative count, received ${count}.`)
+    }
+    return count
+  }
+
+  methods(builtins, proto, [
    [
      "next",
      0,
+      (thisValue) =>
+        Effect.map(receiver(IteratorObj, thisValue, method("next")).cursor.next, (step) =>
+          record(builtins.Object, { value: step.value, done: step.done }),
+        ),
+    ],
+    [
+      "map",
+      1,
+      (thisValue, args) => {
+        const source = ctx.iterateDirect(thisValue)
+        const apply = applyCollectionCallback(ctx, args[0], method("map"))
+        let counter = 0
+        return helper(
+          source,
+          Effect.gen(function* () {
+            const step = yield* source.next
+            if (step.done) return finished
+            return { done: false, value: yield* guarded(source, apply([step.value, counter++])) }
+          }),
+        )
+      },
+    ],
+    [
+      "filter",
+      1,
+      (thisValue, args) => {
+        const source = ctx.iterateDirect(thisValue)
+        const apply = applyCollectionCallback(ctx, args[0], method("filter"))
+        let counter = 0
+        return helper(
+          source,
+          Effect.gen(function* () {
+            while (true) {
+              const step = yield* source.next
+              if (step.done) return finished
+              if (yield* guarded(source, apply([step.value, counter++]))) return step
+            }
+          }),
+        )
+      },
+    ],
+    [
+      "take",
+      1,
+      (thisValue, args) => {
+        const source = ctx.iterateDirect(thisValue)
+        let remaining = limit(args[0], "take")
+        return helper(
+          source,
+          Effect.gen(function* () {
+            if (remaining === 0) {
+              yield* source.close
+              return finished
+            }
+            remaining -= 1
+            return yield* source.next
+          }),
+        )
+      },
+    ],
+    [
+      "drop",
+      1,
+      (thisValue, args) => {
+        const source = ctx.iterateDirect(thisValue)
+        let remaining = limit(args[0], "drop")
+        return helper(
+          source,
+          Effect.gen(function* () {
+            while (remaining > 0) {
+              remaining -= 1
+              const step = yield* source.next
+              if (step.done) return finished
+            }
+            return yield* source.next
+          }),
+        )
+      },
+    ],
+    [
+      "flatMap",
+      1,
+      (thisValue, args) => {
+        const source = ctx.iterateDirect(thisValue)
+        const apply = applyCollectionCallback(ctx, args[0], method("flatMap"))
+        let counter = 0
+        let inner: Cursor<R> | undefined
+        return helper(
+          source,
+          Effect.gen(function* () {
+            while (true) {
+              if (inner !== undefined) {
+                const step = yield* guarded(source, inner.next)
+                if (!step.done) return step
+                inner = undefined
+              }
+              const step = yield* source.next
+              if (step.done) return finished
+              inner = yield* guarded(
+                source,
+                Effect.flatMap(apply([step.value, counter++]), (mapped) =>
+                  flattenable(mapped, method("flatMap"), false),
+                ),
+              )
+            }
+          }),
+          Effect.suspend(() => (inner === undefined ? source.close : Effect.andThen(inner.close, source.close))),
+        )
+      },
+    ],
+    [
+      "reduce",
+      1,
+      (thisValue, args) => {
+        const source = ctx.iterateDirect(thisValue)
+        const apply = applyCollectionCallback(ctx, args[0], method("reduce"))
+        return Effect.gen(function* () {
+          let counter = 0
+          let accumulator = args[1]
+          if (args.length < 2) {
+            const first = yield* source.next
+            if (first.done) throw typeError("Iterator.prototype.reduce of an empty iterator with no initial value.")
+            accumulator = first.value
+            counter = 1
+          }
+          while (true) {
+            const step = yield* source.next
+            if (step.done) return accumulator
+            accumulator = yield* guarded(source, apply([accumulator, step.value, counter++]))
+          }
+        })
+      },
+    ],
+    [
+      "toArray",
+      0,
      (thisValue) => {
-        const step = receiver(IteratorObj, thisValue, "Iterator.prototype.next").iterator.next()
-        return record(builtins.Object, { value: step.value, done: Boolean(step.done) })
+        const source = ctx.iterateDirect(thisValue)
+        return Effect.gen(function* () {
+          const items: Array<Value> = []
+          while (true) {
+            const step = yield* source.next
+            if (step.done) return new Arr(builtins.Array, items)
+            items.push(step.value)
+          }
+        })
+      },
+    ],
+    [
+      "forEach",
+      1,
+      (thisValue, args) => {
+        const source = ctx.iterateDirect(thisValue)
+        const apply = applyCollectionCallback(ctx, args[0], method("forEach"))
+        return Effect.gen(function* () {
+          let counter = 0
+          while (true) {
+            const step = yield* source.next
+            if (step.done) return undefined
+            yield* guarded(source, apply([step.value, counter++]))
+          }
+        })
+      },
+    ],
+    [
+      "some",
+      1,
+      (thisValue, args) => {
+        const source = ctx.iterateDirect(thisValue)
+        const apply = applyCollectionCallback(ctx, args[0], method("some"))
+        return Effect.gen(function* () {
+          let counter = 0
+          while (true) {
+            const step = yield* source.next
+            if (step.done) return false
+            if (yield* guarded(source, apply([step.value, counter++]))) {
+              yield* source.close
+              return true
+            }
+          }
+        })
+      },
+    ],
+    [
+      "every",
+      1,
+      (thisValue, args) => {
+        const source = ctx.iterateDirect(thisValue)
+        const apply = applyCollectionCallback(ctx, args[0], method("every"))
+        return Effect.gen(function* () {
+          let counter = 0
+          while (true) {
+            const step = yield* source.next
+            if (step.done) return true
+            if (!(yield* guarded(source, apply([step.value, counter++])))) {
+              yield* source.close
+              return false
+            }
+          }
+        })
+      },
+    ],
+    [
+      "find",
+      1,
+      (thisValue, args) => {
+        const source = ctx.iterateDirect(thisValue)
+        const apply = applyCollectionCallback(ctx, args[0], method("find"))
+        return Effect.gen(function* () {
+          let counter = 0
+          while (true) {
+            const step = yield* source.next
+            if (step.done) return undefined
+            if (yield* guarded(source, apply([step.value, counter++]))) {
+              yield* source.close
+              return step.value
+            }
+          }
+        })
      },
    ],
  ])
+
+  // Helpers and `Iterator.from` wrappers can be closed; collection iterators, as in JS, cannot.
+  methods(builtins, builtins.IteratorHelper, [
+    [
+      "return",
+      0,
+      (thisValue) =>
+        Effect.map(receiver(IteratorObj, thisValue, "Iterator.prototype.return").cursor.close, () =>
+          record(builtins.Object, { value: undefined, done: true }),
+        ),
+    ],
+  ])
+
+  const iterator = constructor<R>(builtins, proto, {
+    name: "Iterator",
+    length: 0,
+    call: requiresNew("Iterator"),
+    construct: () =>
+      Effect.sync(() => {
+        throw typeError("Iterator is abstract; use Iterator.from(...) or a built-in iterator.")
+      }),
+  })
+  define(
+    iterator,
+    "from",
+    fn(builtins, "from", 1, (_, args) =>
+      Effect.gen(function* () {
+        if (args[0] instanceof Obj && hasPrototype(args[0], proto)) return args[0]
+        return new IteratorObj(builtins.IteratorHelper, yield* flattenable(args[0], "Iterator.from", true))
+      }),
+    ),
+    hidden,
+  )
+  return iterator
 }
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
Aiden Cline	8997d8662f	fix(schema): keep legacy blobs on replay, import, and V1 migration Freeze session.message.content.updated at the stored shape and translate on replay, run persisted() on CLI session import, write native from the V1 migration, regenerate the OpenAPI docs, and mirror text.ended state in the client fold.	2026-09-22 00:37:59 -05:00
Aiden Cline	e4dd41b033	test(core): use native for text and reasoning provider blobs	2026-09-21 23:39:41 -05:00
Aiden Cline	347bf1d749	Merge remote-tracking branch 'origin/v2' into message-native	2026-09-21 23:37:54 -05:00
Aiden Cline	07d48e1ffb	feat(ai): add experimental evaluation API (#50506 )	2026-09-21 23:30:38 -05:00
Aiden Cline	e7c4bffd38	refactor(schema): drop native migration and fix fixtures	2026-09-21 23:27:12 -05:00
Aiden Cline	9fdcb8da41	fix(codemode): coerce built-in arguments as in JS instead of requiring numbers and strings (#50492 )	2026-09-21 23:04:04 -05:00
Aiden Cline	ba61ac6730	fix(ai): preserve Vertex function call ids (#50504 )	2026-09-21 23:03:24 -05:00
Aiden Cline	94b9133910	fix(core): share child prompt cache affinity (#50495 )	2026-09-21 22:44:43 -05:00
Aiden Cline	6f8c5ae0aa	fix(codemode): bind generator parameters at the call, not the first next() (#50489 )	2026-09-21 22:42:10 -05:00
Aiden Cline	60673aaef3	fix(core): run session HTTP hooks on the AI SDK route (#50487 )	2026-09-21 22:41:06 -05:00
Aiden Cline	651529d64e	fix(codemode): coerce any value to a property key (#50479 )	2026-09-21 21:35:20 -05:00
opencode-agent[bot]	532f25d0d4	feat(tui): restore sidebar onboarding (#50475 )	2026-09-21 22:17:22 -04:00
opencode-agent[bot]andjlongster	643c4c3500	fix: remove first-month Go pricing (#50473 ) Co-authored-by: jlongster <17031+jlongster@users.noreply.github.com>	2026-09-21 21:55:12 -04:00
opencode-agent[bot]andBrendonovich	9d531435b4	fix(desktop): stop signing macOS DMGs (#50469 ) Co-authored-by: Brendonovich <14191578+Brendonovich@users.noreply.github.com>	2026-09-22 01:35:21 +00:00
opencode-agent[bot]	5b9dc35eec	feat(tui): add automatic tabs mode (#50456 )	2026-09-22 01:00:26 +00:00
Aiden Cline	1814dd9799	test: stabilize Windows CI without longer timeouts (#50454 )	2026-09-21 18:30:30 -05:00
Aiden Cline	1e1cd042ea	feat(codemode): name the closest tool in unknown-tool errors (#50455 )	2026-09-21 18:14:31 -05:00
Aiden Cline	02566f6219	fix(codemode): live Map/Set forEach, generator prototypes, repeated function declarations, delete on non-references (#50450 )	2026-09-21 18:09:45 -05:00
opencode-agent[bot]andrekram1-node	f488aa3f79	fix(tui): persist MCP sidebar state (#50447 ) Co-authored-by: rekram1-node <rekram1-node@users.noreply.github.com>	2026-09-21 17:28:23 -05:00
Aiden Cline	97457ec7a3	feat(codemode): accept tools.-prefixed namespaces in search (#50438 )	2026-09-21 16:59:31 -05:00
James Long	d62049aab4	fix(tui): set renderer listener budget to 15 (#50442 )	2026-09-21 17:55:27 -04:00
Aiden Cline	096ac95773	fix(codemode): drop the parameter name from rendered signatures (#50435 )	2026-09-21 16:44:46 -05:00
Aiden Cline	4cc9b90f27	fix(codemode): add Promise.try and surface a failing iterator close on generator return (#50419 )	2026-09-21 15:35:11 -05:00
James Long	990463aa9f	refactor(tui): favor dark theme base (#50412 )	2026-09-21 16:23:38 -04:00
opencode-agent[bot]andrekram1-node	cd39063622	test(core): stabilize browser idle attachment (#50418 ) Co-authored-by: rekram1-node <rekram1-node@users.noreply.github.com>	2026-09-21 14:45:33 -05:00
Aiden Cline	4c944a86d7	fix(core): tell the model search is synchronous (#50417 )	2026-09-21 14:35:46 -05:00
Aiden Cline	97e833a297	feat(codemode): add Iterator helpers and Iterator.from (#50410 )	2026-09-21 14:14:24 -05:00
xin zhuangandSimon Klee	b8aa08f260	fix(tui): complete Mini exit aliases (#50388 ) Co-authored-by: Simon Klee <hello@simonklee.dk>	2026-09-21 17:04:58 +00:00
Aiden Cline	3f0118022b	feat(codemode): add Promise.withResolvers, print errors in console, name values in iterable errors (#50389 )	2026-09-21 11:56:15 -05:00
Simon Klee	6f76c31ca7	tui: resize /btw dialog to terminal (#50392 )	2026-09-21 16:44:18 +00:00
Aiden Cline	f90beeb9b8	fix(core): say plainly that catalog tools and search only work inside execute (#50384 )	2026-09-21 11:13:33 -05:00
Adam	4b9a3d80fc	feat(core): enforce Console-managed policies (#49729 )	2026-09-21 11:10:57 -05:00
Aiden Cline	1316576720	refactor(codemode): type program values and let built-ins answer for themselves (#50191 )	2026-09-21 11:03:16 -05:00
opencode-agent[bot]andnexxeln	2f0c861af0	fix(cli): show actionable upgrade errors (#50346 ) Co-authored-by: nexxeln <95541290+nexxeln@users.noreply.github.com>	2026-09-21 19:09:56 +05:30
opencode-agent[bot]	4d94777d4d	chore(core): refresh bundled models.dev snapshot	2026-09-21 12:19:57 +00:00
opencode-agent[bot]	46ebde65e9	chore: update nix node_modules hashes	2026-09-21 11:58:21 +00:00
Luke Parker	932c12ad1d	chore(desktop): upgrade Electron to 44.4.3 (#50327 )	2026-09-21 21:33:49 +10:00
opencode	6f655dcbab	sync release versions for v2.0.12	2026-09-21 09:57:01 +00:00
Luke Parker	ab60f08c69	fix(app): open Review pane for browser focus in background sessions (#50284 )	2026-09-21 06:08:36 +00:00
Luke Parker	60ed84ecd1	feat(app): open agent-referenced files as rich artifact tabs (#49882 )	2026-09-21 15:20:15 +10:00
Luke Parker	8aebed170a	fix(app): show empty review state for projects without VCS (#50265 )	2026-09-21 14:54:47 +10:00
opencode-agent[bot]Brendonovich Kit Langton	14148a0ea4	fix(app): restore server status spacing (#50273 ) Co-authored-by: Brendonovich <14191578+Brendonovich@users.noreply.github.com> Co-authored-by: Kit Langton <kit.langton@gmail.com>	2026-09-21 12:37:19 +08:00
Aiden Cline	7f51fbd878	feat(codemode): rank whole-word path matches above substring matches in search (#50275 )	2026-09-20 22:59:01 -05:00
Aiden Cline	85962e49b7	refactor(schema): rename message provider blobs to native	2026-09-20 21:41:03 -05:00
Aiden Cline	cbdd1f66da	fix(codemode): locate failures in the submitted source (#50197 )	2026-09-20 20:47:54 -05:00
Luke Parker	788eb0fa29	fix(cli): report fatal startup causes on stderr (#50240 )	2026-09-20 22:57:20 +00:00
opencode-agent[bot]andkitlangton	58fcad77a8	feat(tui): copy session ID from tab menu (#50181 ) Co-authored-by: kitlangton <7587245+kitlangton@users.noreply.github.com>	2026-09-20 19:15:37 +00:00
Aiden Cline	c555559ac1	refactor(plugin): name tool execution context (#50195 )	2026-09-20 11:36:19 -05:00
Aiden Cline	e3a3fa7108	fix(plugin): forward Promise tool cancellation (#50190 )	2026-09-20 11:22:49 -05:00
opencode-agent[bot]	6238af397e	chore(core): refresh bundled models.dev snapshot	2026-09-20 16:17:29 +00:00
Aiden Cline	7ffd75faf6	fix(core): restore anthropic budget variants (#50182 )	2026-09-20 10:50:21 -05:00
opencode-agent[bot]	1f8ab95695	chore(core): refresh bundled models.dev snapshot	2026-09-20 15:37:06 +00:00
Aiden Cline	62dc1f7696	feat(codemode): add toLocaleString, Error.isError, and Map.getOrInsert (#50098 )	2026-09-20 10:23:23 -05:00
opencode-agent[bot]	66f10ab7bf	chore(core): refresh bundled models.dev snapshot	2026-09-20 14:37:06 +00:00
opencode-agent[bot]	1ca8f63a79	chore(core): refresh bundled models.dev snapshot	2026-09-20 13:36:51 +00:00
opencode-agent[bot]	03bcdd580d	chore(core): refresh bundled models.dev snapshot	2026-09-20 12:43:39 +00:00
opencode-agent[bot]	cc502f7e5f	chore(core): refresh bundled models.dev snapshot	2026-09-20 11:37:37 +00:00
opencode-agent[bot]	64ce8771c0	chore(core): refresh bundled models.dev snapshot	2026-09-20 10:37:01 +00:00
opencode-agent[bot]	702a73d91a	chore(core): refresh bundled models.dev snapshot	2026-09-20 09:37:50 +00:00
opencode	991b727eb8	sync release versions for v2.0.11	2026-09-20 08:57:41 +00:00
opencode-agent[bot]	ba342ce227	chore(core): refresh bundled models.dev snapshot	2026-09-20 08:42:13 +00:00
David Hill	1464545665	fix(app): center timeline beside summary (#49620 )	2026-09-20 18:06:32 +10:00
David Hill	fecacc9e68	fix(app): match vertical nav tab states (#49619 )	2026-09-20 18:03:49 +10:00
David HillandLukeParkerDev	1f73b4806b	fix(desktop): polish browser panel states and navigation (#49432 ) Co-authored-by: LukeParkerDev <10430890+Hona@users.noreply.github.com>	2026-09-20 07:54:25 +00:00
opencode-agent[bot]	da2ce02596	chore(core): refresh bundled models.dev snapshot	2026-09-20 07:38:48 +00:00
opencode-agent[bot]	25f35dcfb8	chore(core): refresh bundled models.dev snapshot	2026-09-20 06:49:40 +00:00
Luke Parker	717f81ce08	chore(desktop): attribute renderer CPU profiles to source files (#50114 )	2026-09-20 16:30:35 +10:00
Luke Parker	5fdfcc7a80	perf(desktop): hand the window its persisted stores before the first render (#50113 )	2026-09-20 16:29:02 +10:00
Luke Parker	0530c8e512	perf(desktop): talk to the main process without the Effect runtime in the renderer (#50112 )	2026-09-20 16:26:08 +10:00
Luke Parker	1d8cf4564b	perf(desktop): move startup work that the first window does not need off its path (#50111 )	2026-09-20 16:23:37 +10:00
Luke Parker	7e88f6bb18	perf(desktop): bundle the renderer's initial module graph as one chunk (#50110 )	2026-09-20 16:19:28 +10:00
Luke Parker	af592fb779	perf(desktop): serve the renderer's first assets before evaluating the main bundle (#50109 )	2026-09-20 16:18:50 +10:00
Luke Parker	7fc3f68007	perf(desktop): boot the renderer alongside the main bundle (#50108 )	2026-09-20 16:15:58 +10:00
opencode-agent[bot]	cdcbb0047e	chore(core): refresh bundled models.dev snapshot	2026-09-20 05:38:29 +00:00
opencode-agent[bot]	a1956a7522	chore(core): refresh bundled models.dev snapshot	2026-09-20 04:42:05 +00:00
opencode-agent[bot]	55bc7fd403	chore(core): refresh bundled models.dev snapshot	2026-09-20 03:43:32 +00:00
opencode-agent[bot]	3049b1e684	chore(core): refresh bundled models.dev snapshot	2026-09-20 02:45:23 +00:00
opencode-agent[bot]	1f36a7aff8	chore(core): refresh bundled models.dev snapshot	2026-09-20 01:31:11 +00:00