refactor(ai): trim effort update comments and tests

.github/workflows/publish.yml

@@ -25,7 +25,7 @@ on:
         required: false
         type: string
 
-concurrency: ${{ github.workflow }}-${{ github.ref }}-${{ (github.ref_name == 'v2' && (inputs.version || inputs.bump) && 'release') || inputs.version || inputs.bump }}
+concurrency: ${{ github.workflow }}-${{ github.ref }}-${{ inputs.version || inputs.bump }}
 
 permissions:
   id-token: write
@@ -33,7 +33,7 @@ permissions:
   packages: write
 
 env:
-  OPENCODE_CHANNEL: ${{ (github.ref_name == 'v2' && !inputs.bump && !inputs.version && 'dev') || '' }}
+  OPENCODE_CHANNEL: ${{ (github.ref_name == 'v2' && 'dev') || '' }}
 
 jobs:
   version:
@@ -168,7 +168,7 @@ jobs:
           fi
 
           found=0
-          for file in packages/cli/dist/cli-darwin-*/bin/opencode; do
+          for file in packages/cli/dist/cli-darwin-*/bin/opencode2; do
             if [ ! -f "$file" ]; then
               continue
             fi
@@ -378,7 +378,7 @@ jobs:
     needs:
       - version
       - sign-cli-macos
-    if: github.repository == 'anomalyco/opencode' && (github.ref_name != 'v2' || needs.version.outputs.release != '')
+    if: github.repository == 'anomalyco/opencode' && github.ref_name != 'v2'
     continue-on-error: false
     env:
       AZURE_CLIENT_ID: ${{ secrets.AZURE_CLIENT_ID }}

AGENTS.md

@@ -8,9 +8,9 @@
 
 ## Live V2 TUI Testing
 
-- Run `bun run dev:live` from a development worktree to test its TUI against the currently elected `opencode` background server and live sessions.
+- Run `bun run dev:live` from a development worktree to test its TUI against the currently elected `opencode2` background server and live sessions.
 - Pass a directory after the script when needed, for example `bun run dev:live /path/to/project`.
-- The script discovers the server with `opencode service status`, injects its private local credential from `opencode service get password`, and uses the `dev` TUI storage channel so tabs and other client-local state match the installed client.
+- The script discovers the server with `opencode2 service status`, injects its private local credential from `opencode2 service get password`, and uses the `dev` TUI storage channel so tabs and other client-local state match the installed client.
 - Prefer `dev:live` over plain `bun run dev` for this workflow. An implicit managed-service connection may replace the live server when the worktree client version differs; explicit `--server` warns and continues without replacing it.
 
 ## V2 TUI Stories

bun.lock

@@ -31,7 +31,7 @@
     },
     "packages/ai": {
       "name": "@opencode/ai",
-      "version": "2.0.0",
+      "version": "1.17.20",
       "dependencies": {
         "@aws-sdk/credential-providers": "3.1057.0",
         "@opencode/schema": "workspace:*",
@@ -53,7 +53,7 @@
     },
     "packages/app": {
       "name": "@opencode/app",
-      "version": "2.0.0",
+      "version": "1.18.15",
       "dependencies": {
         "@corvu/drawer": "catalog:",
         "@dnd-kit/abstract": "0.5.0",
@@ -111,7 +111,7 @@
     },
     "packages/cli": {
       "name": "@opencode/cli",
-      "version": "2.0.0",
+      "version": "1.18.4",
       "bin": {
         "opencode2": "./bin/opencode2.cjs",
       },
@@ -175,7 +175,7 @@
     },
     "packages/client": {
       "name": "@opencode/client",
-      "version": "2.0.0",
+      "version": "1.17.13",
       "dependencies": {
         "@opencode/protocol": "workspace:*",
         "@opencode/schema": "workspace:*",
@@ -201,7 +201,7 @@
     },
     "packages/codemode": {
       "name": "@opencode/codemode",
-      "version": "2.0.0",
+      "version": "1.18.4",
       "dependencies": {
         "acorn": "8.15.0",
         "effect": "catalog:",
@@ -215,7 +215,7 @@
     },
     "packages/console/app": {
       "name": "@opencode/console-app",
-      "version": "2.0.0",
+      "version": "1.18.15",
       "dependencies": {
         "@cloudflare/vite-plugin": "1.15.2",
         "@ibm/plex": "6.4.1",
@@ -251,7 +251,7 @@
     },
     "packages/console/core": {
       "name": "@opencode/console-core",
-      "version": "2.0.0",
+      "version": "1.18.15",
       "dependencies": {
         "@aws-sdk/client-sts": "3.782.0",
         "@jsx-email/render": "1.1.1",
@@ -278,7 +278,7 @@
     },
     "packages/console/function": {
       "name": "@opencode/console-function",
-      "version": "2.0.0",
+      "version": "1.18.15",
       "dependencies": {
         "@openauthjs/openauth": "0.0.0-20250322224806",
         "@opencode/console-core": "workspace:*",
@@ -295,7 +295,7 @@
     },
     "packages/console/mail": {
       "name": "@opencode/console-mail",
-      "version": "2.0.0",
+      "version": "1.18.15",
       "dependencies": {
         "@jsx-email/all": "2.2.3",
         "@jsx-email/cli": "1.4.3",
@@ -319,7 +319,7 @@
     },
     "packages/console/support": {
       "name": "@opencode/console-support",
-      "version": "2.0.0",
+      "version": "1.18.15",
       "dependencies": {
         "@cloudflare/vite-plugin": "1.15.2",
         "@opencode/console-core": "workspace:*",
@@ -339,7 +339,7 @@
     },
     "packages/core": {
       "name": "@opencode/core",
-      "version": "2.0.0",
+      "version": "1.18.4",
       "dependencies": {
         "@ai-sdk/alibaba": "1.0.17",
         "@ai-sdk/anthropic": "3.0.82",
@@ -411,7 +411,7 @@
     },
     "packages/desktop": {
       "name": "@opencode/desktop",
-      "version": "2.0.0",
+      "version": "1.18.15",
       "dependencies": {
         "@zip.js/zip.js": "2.7.62",
         "electron-context-menu": "4.1.2",
@@ -463,7 +463,7 @@
     },
     "packages/enterprise": {
       "name": "@opencode/enterprise",
-      "version": "2.0.0",
+      "version": "1.18.15",
       "dependencies": {
         "@hono/standard-validator": "catalog:",
         "@opencode-ai/sdk": "1.18.21",
@@ -500,7 +500,7 @@
     },
     "packages/function": {
       "name": "@opencode/function",
-      "version": "2.0.0",
+      "version": "1.18.15",
       "dependencies": {
         "@octokit/auth-app": "8.0.1",
         "@octokit/rest": "catalog:",
@@ -516,7 +516,7 @@
     },
     "packages/http-recorder": {
       "name": "@opencode/http-recorder",
-      "version": "2.0.0",
+      "version": "1.18.15",
       "dependencies": {
         "@effect/platform-node-shared": "4.0.0-rc.112",
       },
@@ -535,7 +535,7 @@
     },
     "packages/httpapi-codegen": {
       "name": "@opencode/httpapi-codegen",
-      "version": "2.0.0",
+      "version": "0.0.0",
       "dependencies": {
         "effect": "catalog:",
         "prettier": "3.6.2",
@@ -548,7 +548,7 @@
     },
     "packages/latex": {
       "name": "@opencode/latex",
-      "version": "2.0.0",
+      "version": "0.0.0",
       "dependencies": {
         "@opencode/plugin": "workspace:*",
         "@opentui/core": "catalog:",
@@ -562,7 +562,7 @@
     },
     "packages/merman": {
       "name": "@opencode/merman",
-      "version": "2.0.0",
+      "version": "0.0.0",
       "dependencies": {
         "@opencode/plugin": "workspace:*",
         "@opentui/core": "catalog:",
@@ -577,7 +577,7 @@
     },
     "packages/plugin": {
       "name": "@opencode/plugin",
-      "version": "2.0.0",
+      "version": "1.18.15",
       "dependencies": {
         "@ai-sdk/provider": "3.0.8",
         "@opencode/ai": "workspace:*",
@@ -616,7 +616,7 @@
     },
     "packages/plugin-browser": {
       "name": "@opencode/plugin-browser",
-      "version": "2.0.0",
+      "version": "0.0.0",
       "dependencies": {
         "@opencode/plugin": "workspace:*",
         "@opencode/schema": "workspace:*",
@@ -646,7 +646,7 @@
     },
     "packages/protocol": {
       "name": "@opencode/protocol",
-      "version": "2.0.0",
+      "version": "1.17.11",
       "dependencies": {
         "@opencode/schema": "workspace:*",
         "effect": "catalog:",
@@ -661,7 +661,7 @@
     },
     "packages/schema": {
       "name": "@opencode/schema",
-      "version": "2.0.0",
+      "version": "1.17.11",
       "dependencies": {
         "@standard-schema/spec": "catalog:",
         "effect": "catalog:",
@@ -685,7 +685,7 @@
     },
     "packages/sdk": {
       "name": "@opencode/sdk",
-      "version": "2.0.0",
+      "version": "1.18.4",
       "dependencies": {
         "@opencode/client": "workspace:*",
         "@opencode/core": "workspace:*",
@@ -706,7 +706,7 @@
     },
     "packages/server": {
       "name": "@opencode/server",
-      "version": "2.0.0",
+      "version": "1.18.4",
       "dependencies": {
         "@effect/platform-node": "catalog:",
         "@effect/platform-node-shared": "catalog:",
@@ -728,7 +728,7 @@
     },
     "packages/session-ui": {
       "name": "@opencode/session-ui",
-      "version": "2.0.0",
+      "version": "1.18.15",
       "dependencies": {
         "@kobalte/core": "catalog:",
         "@opencode/client": "workspace:*",
@@ -763,7 +763,7 @@
     },
     "packages/simulation": {
       "name": "@opencode/simulation",
-      "version": "2.0.0",
+      "version": "1.17.13",
       "dependencies": {
         "@opencode/ai": "workspace:*",
         "@opencode/core": "workspace:*",
@@ -783,7 +783,7 @@
     },
     "packages/stats/app": {
       "name": "@opencode/stats-app",
-      "version": "2.0.0",
+      "version": "1.18.15",
       "dependencies": {
         "@ibm/plex": "6.4.1",
         "@kobalte/core": "catalog:",
@@ -817,7 +817,7 @@
     },
     "packages/stats/core": {
       "name": "@opencode/stats-core",
-      "version": "2.0.0",
+      "version": "1.18.15",
       "dependencies": {
         "@aws-sdk/client-athena": "3.933.0",
         "@planetscale/database": "1.19.0",
@@ -836,7 +836,7 @@
     },
     "packages/stats/server": {
       "name": "@opencode/stats-server",
-      "version": "2.0.0",
+      "version": "1.18.15",
       "dependencies": {
         "@aws-sdk/client-firehose": "3.933.0",
         "@effect/platform-node": "catalog:",
@@ -882,7 +882,7 @@
     },
     "packages/theme": {
       "name": "@opencode/theme",
-      "version": "2.0.0",
+      "version": "0.0.0",
       "dependencies": {
         "@opentui/core": "catalog:",
         "effect": "catalog:",
@@ -896,7 +896,7 @@
     },
     "packages/tui": {
       "name": "@opencode/tui",
-      "version": "2.0.0",
+      "version": "1.18.4",
       "dependencies": {
         "@opencode/client": "workspace:*",
         "@opencode/core": "workspace:*",
@@ -931,7 +931,7 @@
     },
     "packages/ui": {
       "name": "@opencode/ui",
-      "version": "2.0.0",
+      "version": "1.18.15",
       "dependencies": {
         "@kobalte/core": "catalog:",
         "@pierre/diffs": "catalog:",
@@ -966,7 +966,7 @@
     },
     "packages/util": {
       "name": "@opencode/util",
-      "version": "2.0.0",
+      "version": "1.18.3",
       "dependencies": {
         "@effect/opentelemetry": "catalog:",
         "@effect/platform-node": "catalog:",
@@ -999,7 +999,7 @@
     },
     "packages/web": {
       "name": "@opencode/web",
-      "version": "2.0.0",
+      "version": "1.18.15",
       "dependencies": {
         "@astrojs/cloudflare": "12.6.3",
         "@astrojs/markdown-remark": "6.3.1",
@@ -1040,7 +1040,7 @@
     },
     "services/update": {
       "name": "@opencode/update",
-      "version": "2.0.0",
+      "version": "1.18.4",
       "dependencies": {
         "jose": "6.0.11",
         "semver": "catalog:",

install

@@ -1,7 +1,6 @@
 #!/usr/bin/env bash
 set -euo pipefail
-APP=opencode
-SOURCE_APP=opencode
+APP=opencode2
 
 MUTED='\033[0;2m'
 RED='\033[0;31m'
@@ -23,7 +22,7 @@ Options:
 Examples:
     curl -fsSL https://opencode.ai/v2/install | bash
     curl -fsSL https://opencode.ai/v2/install | bash -s -- --version 0.0.0-beta-17236
-    ./install --binary /path/to/opencode
+    ./install --binary /path/to/opencode2
 EOF
 }
 
@@ -202,9 +201,9 @@ else
 
     filename="cli-$target-$specific_version.tgz"
     url="https://registry.npmjs.org/$package_name/-/$filename"
-    binary_name="$SOURCE_APP"
+    binary_name="$APP"
     if [ "$os" = "windows" ]; then
-        binary_name="$SOURCE_APP.exe"
+        binary_name="$APP.exe"
     fi
 fi
 
@@ -231,7 +230,12 @@ check_version() {
         installed_version="${installed_version##* }"
         installed_version="${installed_version#v}"
 
-        print_message info "${MUTED}Installed version: ${NC}$installed_version."
+        if [[ "$installed_version" != "$specific_version" ]]; then
+            print_message info "${MUTED}Installed version: ${NC}$installed_version."
+        else
+            print_message info "${MUTED}Version ${NC}$specific_version${MUTED} already installed"
+            exit 0
+        fi
     fi
 }
 
@@ -336,47 +340,15 @@ download_and_install() {
     fi
 
     tar -xzf "$tmp_dir/$filename" -C "$tmp_dir"
-    local installed_binary="$APP"
-    if [ "$os" = "windows" ]; then
-        installed_binary="$APP.exe"
-    fi
-    mv "$tmp_dir/package/bin/$binary_name" "$INSTALL_DIR/$installed_binary"
-    chmod 755 "$INSTALL_DIR/$installed_binary"
+    mv "$tmp_dir/package/bin/$binary_name" "$INSTALL_DIR"
+    chmod 755 "${INSTALL_DIR}/$binary_name"
     rm -rf "$tmp_dir"
 }
 
 install_from_binary() {
     print_message info "\n${MUTED}Installing ${NC}$APP ${MUTED}from: ${NC}$binary_path"
-    local installed_binary="$APP"
-    case "$(uname -s)" in
-        MINGW*|MSYS*|CYGWIN*) installed_binary="$APP.exe" ;;
-    esac
-    cp "$binary_path" "$INSTALL_DIR/$installed_binary"
-    chmod 755 "$INSTALL_DIR/$installed_binary"
-}
-
-install_legacy_shim() {
-    local shim_os="${os:-}"
-    if [[ -z "$shim_os" ]]; then
-        case "$(uname -s)" in
-            MINGW*|MSYS*|CYGWIN*) shim_os="windows" ;;
-        esac
-    fi
-    rm -f "$INSTALL_DIR/opencode2" "$INSTALL_DIR/opencode2.exe" "$INSTALL_DIR/opencode2.cmd"
-    if [[ "$shim_os" == "windows" ]]; then
-        cat > "$INSTALL_DIR/opencode2.cmd" <<'EOF'
-@echo off
-echo opencode2 is now just opencode. run opencode
-exit /b 1
-EOF
-        return
-    fi
-    cat > "$INSTALL_DIR/opencode2" <<'EOF'
-#!/bin/sh
-echo 'opencode2 is now just opencode. run opencode'
-exit 1
-EOF
-    chmod 755 "$INSTALL_DIR/opencode2"
+    cp "$binary_path" "${INSTALL_DIR}/$APP"
+    chmod 755 "${INSTALL_DIR}/$APP"
 }
 
 if [ -n "$binary_path" ]; then
@@ -385,7 +357,6 @@ else
     check_version
     download_and_install
 fi
-install_legacy_shim
 
 
 add_to_path() {
@@ -482,7 +453,7 @@ echo -e ""
 echo -e "${MUTED}OpenCode includes free models, to start:${NC}"
 echo -e ""
 echo -e "cd <project>  ${MUTED}# Open directory${NC}"
-echo -e "opencode      ${MUTED}# Run command${NC}"
+echo -e "opencode2     ${MUTED}# Run command${NC}"
 echo -e ""
 echo -e "${MUTED}For more information visit ${NC}https://opencode.ai/v2/docs"
 echo -e ""

package.json

@@ -2,15 +2,15 @@
   "$schema": "https://json.schemastore.org/package.json",
   "name": "opencode",
   "description": "AI-powered development tool",
-  "version": "2.0.0",
+  "version": "0.0.0",
   "private": true,
   "type": "module",
   "packageManager": "bun@1.4.2",
   "scripts": {
     "dev": "bun run --cwd packages/cli src/index.ts",
-    "dev:live": "sh -c 'OPENCODE_TUI_CHANNEL=dev OPENCODE_PASSWORD=\"$(opencode service get password)\" exec bun run dev \"$@\" --server \"$(opencode service status)\"' --",
+    "dev:live": "sh -c 'OPENCODE_TUI_CHANNEL=dev OPENCODE_PASSWORD=\"$(opencode2 service get password)\" exec bun run dev \"$@\" --server \"$(opencode2 service status)\"' --",
     "dev:vite": "bun run --cwd packages/cli --conditions=browser dev/vite.ts",
-    "dev:vite:live": "sh -c 'OPENCODE_TUI_CHANNEL=dev OPENCODE_PASSWORD=\"$(opencode service get password)\" exec bun run dev:vite \"$@\" --server \"$(opencode service status)\"' --",
+    "dev:vite:live": "sh -c 'OPENCODE_TUI_CHANNEL=dev OPENCODE_PASSWORD=\"$(opencode2 service get password)\" exec bun run dev:vite \"$@\" --server \"$(opencode2 service status)\"' --",
     "dev:desktop": "bun --cwd packages/desktop dev",
     "dev:web": "bun --cwd packages/app dev",
     "dev:console": "ulimit -n 10240 2>/dev/null; bun run --cwd packages/console/app dev",

packages/ai/AGENTS.md

@@ -122,14 +122,13 @@ Keep provider facades small and explicit:
 
 ### Provider Package Entrypoints
 
-Catalog-selected native providers use package-like export paths from `@opencode/ai`. They are internal entrypoints in one npm package, not separately published provider packages. Every entrypoint implements `ProviderPackage.Definition` and exposes `model(modelID, settings)`, where settings are one flat serializable object: the connection keys the entrypoint declares (`apiKey`, `baseURL`, `region`, …), the common `headers` and `body` overlays, and the protocol's request options (`reasoningEffort`, `thinking`, …) side by side. Each entrypoint destructures its own connection keys and passes the rest to the route as `providerOptions`; there is no nested `providerOptions` at the entrypoint.
+Catalog-selected native providers use package-like export paths from `@opencode/ai`. They are internal entrypoints in one npm package, not separately published provider packages. Every entrypoint implements `ProviderPackage.Definition` and exposes `model(modelID, settings)`, where settings are serializable provider configuration plus common `headers`, `body`, and `limits` overlays.
 
 ```ts
 import { model } from "@opencode/ai/providers/openai/responses"
 
 const selected = model("gpt-5", {
   apiKey,
-  reasoningEffort: "high",
 })
 ```
 
@@ -166,6 +165,10 @@ Native chronological system messages are route/model-specific. Open Responses lo
 
 The wrapped-user fallback preserves ordering while visibly lowering authority. Never silently pass a raw chronological `role: "system"` through a route that might reject it. Do not insert raw retrieved documents, tool output, or web content into privileged chronological system updates; keep untrusted content in ordinary user/tool channels.
 
+### Effort Updates
+
+`Message.effort({ effort, previous })` is a chronological "reasoning effort changed here" marker (`undefined` means the model default). Changing a top-level effort invalidates the whole provider prompt cache, so protocols with a native per-message update (`Protocol.supportsEffortUpdates`) keep the top-level effort at the first marker's `previous` and lower each marker in place: Anthropic Messages emits an empty `role: "system"` message with `output_config.effort` plus the `mid-conversation-output-config-2026-07-01` beta, and OpenAI Responses emits `configuration_update` items. `applyEffortUpdates` runs in `prepareRequest` and strips the markers for every other route, so a protocol without support keeps today's plain top-level behaviour. When the last marker disagrees with the effort the request asks for (reverted or forked history), `resolveEffortUpdates` strips the markers and falls back to a plain top-level change.
+
 ### Tools
 
 Tool loops are represented in common messages and events:

packages/ai/package.json

@@ -1,6 +1,6 @@
 {
   "$schema": "https://json.schemastore.org/package.json",
-  "version": "2.0.0",
+  "version": "1.17.20",
   "name": "@opencode/ai",
   "type": "module",
   "license": "MIT",

packages/ai/src/cache-policy.ts

@@ -12,6 +12,7 @@
 // count against the four-breakpoint budget; auto only fills remaining slots.
 import { CacheHint, type CachePolicy, type CachePolicyObject } from "./schema/options.js"
 import { LLMRequest, Message, ToolDefinition, type ContentPart, type ToolEntry } from "./schema/messages.js"
+import { effortUpdate } from "./effort-updates.js"
 
 const AUTO: CachePolicyObject = {
   tools: true,
@@ -121,9 +122,15 @@ const markMessages = (
     return markMessageAt(messages, lastIndexOfRole(messages, "user"), hint, budget)
   if (strategy === "latest-assistant")
     return markMessageAt(messages, lastIndexOfRole(messages, "assistant"), hint, budget)
-  const start = Math.max(0, messages.length - strategy.tail)
+  let start = messages.length
+  let remaining = strategy.tail
+  while (remaining > 0 && start > 0) {
+    start -= 1
+    if (effortUpdate(messages[start]!) === undefined) remaining -= 1
+  }
   let next = messages
-  for (let i = start; i < messages.length; i++) next = markMessageAt(next, i, hint, budget)
+  for (let i = start; i < messages.length; i++)
+    if (effortUpdate(messages[i]!) === undefined) next = markMessageAt(next, i, hint, budget)
   return next
 }
 

packages/ai/src/effort-updates.ts

@@ -0,0 +1,27 @@
+// A top-level reasoning effort change invalidates the whole provider prompt cache, so a
+// mid-conversation switch travels as a `Message.effort(...)` marker: protocols with a native
+// per-message update freeze the top-level effort and lower the markers; every other route strips them.
+import { LLMRequest, type EffortPart, type Message } from "./schema/messages.js"
+
+export const effortUpdate = (message: Message): EffortPart | undefined => {
+  if (message.role !== "system" || message.content.length !== 1) return undefined
+  const part = message.content[0]
+  return part.type === "effort" ? part : undefined
+}
+
+export const stripEffortUpdates = (request: LLMRequest) => {
+  const messages = request.messages.filter((message) => effortUpdate(message) === undefined)
+  return messages.length === request.messages.length ? request : LLMRequest.update(request, { messages })
+}
+
+export const applyEffortUpdates = (request: LLMRequest): LLMRequest =>
+  request.model.route.supportsEffortUpdates?.(request) ? request : stripEffortUpdates(request)
+
+// The markers must end at `current`: `revert.ts` never touches `session.model` and forks may select
+// another variant, so on disagreement fall back to a plain top-level change instead of misreporting effort.
+export const resolveEffortUpdates = (request: LLMRequest, current: string | undefined) => {
+  const updates = request.messages.flatMap((message) => effortUpdate(message) ?? [])
+  if (updates.length === 0) return { request, effort: current }
+  if (updates.at(-1)?.effort !== current) return { request: stripEffortUpdates(request), effort: current }
+  return { request, effort: updates[0]?.previous }
+}

packages/ai/src/protocols/anthropic-messages.ts

@@ -27,6 +27,7 @@ import {
 } from "../schema/index.js"
 import { JsonObject, optionalArray, optionalNull, ProviderShared } from "./shared.js"
 import { classifyProviderFailure } from "../provider-error.js"
+import { effortUpdate, resolveEffortUpdates } from "../effort-updates.js"
 import * as Cache from "./utils/cache.js"
 import { Lifecycle } from "./utils/lifecycle.js"
 import { ToolSchemaProjection } from "./utils/tool-schema.js"
@@ -36,6 +37,7 @@ const ADAPTER = "anthropic-messages"
 export const DEFAULT_BASE_URL = "https://api.anthropic.com/v1"
 export const PATH = "/messages"
 export const DEFAULT_MAX_TOKENS = 32_000
+const DEFAULT_EFFORT = "high"
 
 const SSE_EVENTS = new Set([
   "message",
@@ -286,7 +288,11 @@ type AnthropicToolResultBlock = Schema.Schema.Type<typeof AnthropicToolResultBlo
 const AnthropicMessage = Schema.Union([
   Schema.Struct({ role: Schema.Literal("user"), content: Schema.Array(AnthropicUserBlock) }),
   Schema.Struct({ role: Schema.Literal("assistant"), content: Schema.Array(AnthropicAssistantBlock) }),
-  Schema.Struct({ role: Schema.Literal("system"), content: Schema.Array(AnthropicTextBlock) }),
+  Schema.Struct({
+    role: Schema.Literal("system"),
+    content: Schema.Array(AnthropicTextBlock),
+    output_config: Schema.optional(Schema.Struct({ effort: Schema.String })),
+  }),
 ]).pipe(Schema.toTaggedUnion("role"))
 type AnthropicMessage = Schema.Schema.Type<typeof AnthropicMessage>
 
@@ -877,6 +883,12 @@ const lowerMessages = Effect.fn("AnthropicMessages.lowerMessages")(function* (
 
   for (const [index, message] of request.messages.entries()) {
     if (message.role === "system") {
+      const update = effortUpdate(message)
+      if (update) {
+        // Accepted at any position, so the text-update placement rules do not apply.
+        messages.push({ role: "system", content: [], output_config: { effort: update.effort ?? DEFAULT_EFFORT } })
+        continue
+      }
       if (splitsLocalToolResults(request.messages, index))
         return yield* invalid("Anthropic Messages system updates cannot split a local tool call from its tool result")
       if (supportsNativeSystemUpdates(request) && canUseNativeSystemUpdate(request, index)) {
@@ -1034,18 +1046,11 @@ const resolveOptions = Effect.fn("AnthropicMessages.resolveOptions")(function* (
     ProviderShared.isRecord(rawOutputConfig) && ProviderShared.isRecord(rawOutputConfig.format)
       ? (rawOutputConfig.format as { type: "json_schema"; schema: Record<string, unknown> })
       : undefined
-  const output_config =
-    outputConfigEffort === undefined && outputConfigFormat === undefined
-      ? undefined
-      : {
-          ...(outputConfigEffort === undefined ? {} : { effort: outputConfigEffort }),
-          ...(outputConfigFormat === undefined ? {} : { format: outputConfigFormat }),
-        }
   const thinking = yield* resolveThinking(input?.thinking)
   return {
     thinking: applyThinkingBindingDefault(request.model, thinking),
     effort: outputConfigEffort,
-    output_config,
+    format: outputConfigFormat,
     service_tier,
     metadata,
     container,
@@ -1054,15 +1059,30 @@ const resolveOptions = Effect.fn("AnthropicMessages.resolveOptions")(function* (
   }
 })
 
+// Accept gateway namespaces and Vertex suffixes without treating a snapshot date as a minor version.
+const claudeVersion = (id: string) => {
+  const match = /(?:^|[./])claude-(?<family>[a-z]+)-(?<major>\d+)(?:[.-](?<minor>\d{1,2}))?(?:$|[-:@])/.exec(
+    id.toLowerCase(),
+  )?.groups
+  if (!match) return undefined
+  return { family: match.family, major: Number(match.major), minor: Number(match.minor ?? 0) }
+}
+
 const supportsThinkingBlockBinding = (model: LLMRequest["model"]) => {
   const override = model.compatibility?.supportsThinkingBlockBinding
   if (override !== undefined) return override
-  // Accept gateway namespaces and Vertex suffixes without treating a snapshot date as a minor version.
-  const version = /(?:^|[./])claude-[a-z]+-(?<major>\d+)(?:[.-](?<minor>\d{1,2}))?(?:$|[-:@])/i.exec(model.id)?.groups
-  if (!version) return false
-  const major = Number(version.major)
-  const minor = Number(version.minor ?? 0)
-  return major > 5 || (major === 5 && minor >= 1)
+  const version = claudeVersion(model.id)
+  return version !== undefined && (version.major > 5 || (version.major === 5 && version.minor >= 1))
+}
+
+const supportsEffortUpdates = (model: LLMRequest["model"]) => {
+  const override = model.compatibility?.supportsEffortUpdates
+  if (override !== undefined) return override
+  const version = claudeVersion(model.id)
+  if (version === undefined) return false
+  if (version.family === "opus") return version.major >= 5
+  if (version.family !== "fable" && version.family !== "mythos") return false
+  return version.major > 5 || (version.major === 5 && version.minor >= 1)
 }
 
 const applyThinkingBindingDefault = (model: LLMRequest["model"], thinking: AnthropicThinking | undefined) => {
@@ -1104,13 +1124,15 @@ const fromRequest = Effect.fn("AnthropicMessages.fromRequest")(function* (reques
   const management = yield* ProviderShared.validateWith(
     Schema.decodeUnknownEffect(Schema.UndefinedOr(ContextManagement)),
   )(request.providerOptions?.contextManagement)
+  const options = yield* resolveOptions(request)
+  const updates = resolveEffortUpdates(request, options.effort)
   const generation = request.generation
   const toolSchemaCompatibility = request.model.compatibility?.toolSchema
   // Allocate the 4-breakpoint budget in invalidation order: tools → system →
   // messages. Tools live highest in the cache hierarchy, so when callers
   // over-mark we keep their tool hints and shed the message-tail ones first.
   const breakpoints = Cache.newBreakpoints(ANTHROPIC_BREAKPOINT_CAP)
-  const flattened = ProviderShared.flattenToolRequest(request)
+  const flattened = ProviderShared.flattenToolRequest(updates.request)
   const tools =
     flattened.tools.length === 0
       ? undefined
@@ -1138,7 +1160,13 @@ const fromRequest = Effect.fn("AnthropicMessages.fromRequest")(function* (reques
       `Anthropic Messages: dropped ${breakpoints.dropped} cache breakpoint(s); the API allows at most ${ANTHROPIC_BREAKPOINT_CAP} per request.`,
     )
   }
-  const options = yield* resolveOptions(request)
+  const output_config =
+    updates.effort === undefined && options.format === undefined
+      ? undefined
+      : {
+          ...(updates.effort === undefined ? {} : { effort: updates.effort }),
+          ...(options.format === undefined ? {} : { format: options.format }),
+        }
   const body = {
     model: request.model.id,
     system,
@@ -1152,7 +1180,7 @@ const fromRequest = Effect.fn("AnthropicMessages.fromRequest")(function* (reques
     top_k: generation?.topK,
     stop_sequences: generation?.stop,
     thinking: options.thinking,
-    output_config: options.output_config,
+    output_config,
     // top-level passthrough per SDK MessageCreateParamsBase:4638,4643,4649,4654,4670
     cache_control: options.cache_control,
     container: options.container,
@@ -1677,6 +1705,7 @@ export const protocol = Protocol.make({
     }),
     step,
   },
+  supportsEffortUpdates: (request) => supportsEffortUpdates(request.model),
 })
 
 export const transport = <
@@ -1708,16 +1737,16 @@ export const transport = <
 }
 
 function requiredBetaHeaders(body: Pick<AnthropicMessagesBody, "messages" | "context_management" | "thinking">) {
-  // Always request interleaved thinking. The API accepts the header on any
-  // model and ignores it where unsupported, while manual-thinking models need
-  // it for thinking between tool calls.
-  const betas: string[] = ["interleaved-thinking-2025-05-14"]
+  const betas: string[] = []
   const requestsCompaction = (body.context_management?.edits.length ?? 0) > 0
   const replaysCompaction = body.messages.some((message) =>
     message.content.some((block) => block.type === "compaction"),
   )
   if (requestsCompaction || replaysCompaction) betas.push("compact-2026-01-12")
 
+  if (body.messages.some((message) => message.role === "system" && message.output_config !== undefined))
+    betas.push("mid-conversation-output-config-2026-07-01")
+
   const thinking = body.thinking
   if (thinking && thinking.type !== "disabled" && thinking.block_binding)
     betas.push("thinking-binding-controls-2026-08-01")

packages/ai/src/protocols/open-responses.ts

@@ -20,6 +20,7 @@ import {
 } from "../schema/index.js"
 import { JsonObject, optionalArray, optionalNull, ProviderShared } from "./shared.js"
 import { classifyProviderFailure } from "../provider-error.js"
+import { effortUpdate } from "../effort-updates.js"
 import { OpenResponsesOptions } from "./utils/open-responses-options.js"
 import { Lifecycle } from "./utils/lifecycle.js"
 import { ToolSchemaProjection } from "./utils/tool-schema.js"
@@ -164,6 +165,13 @@ export const CompactionItem = Schema.Struct({
   encrypted_content: Schema.String,
 })
 
+// Kept out of the baseline `InputItem` union: only the OpenAI extension accepts it.
+export const ConfigurationUpdate = Schema.Struct({
+  type: Schema.Literal("configuration_update"),
+  reasoning: Schema.Struct({ effort: OpenResponsesOptions.ReasoningEffort }),
+})
+type ConfigurationUpdate = Schema.Schema.Type<typeof ConfigurationUpdate>
+
 export const InputItem = Schema.Union([
   CompactionItem,
   Schema.Struct({ role: Schema.tag("system"), content: Schema.String }),
@@ -208,6 +216,7 @@ export type HostedToolReplayItem = {
 type LoweredInputItem =
   | OpenResponsesInputItem
   | HostedToolReplayItem
+  | ConfigurationUpdate
   | {
       readonly type: "message"
       readonly id?: string
@@ -634,6 +643,8 @@ const lowerToolResultOutput = Effect.fnUntraced(function* (
   return yield* Effect.forEach(content, (item) => lowerToolResultContentItem(item, request, adapter))
 })
 
+const DEFAULT_EFFORT = "medium"
+
 const lowerMessages = Effect.fn("OpenResponses.lowerMessages")(function* (
   request: LLMRequest,
   adapter: ProviderAdapter,
@@ -646,6 +657,14 @@ const lowerMessages = Effect.fn("OpenResponses.lowerMessages")(function* (
       Schema.decodeUnknownEffect(Schema.UndefinedOr(MessageMetadata)),
     )(message.providerMetadata?.[providerMetadataKey])
     if (message.role === "system") {
+      const update = effortUpdate(message)
+      if (update) {
+        // Consecutive updates are rejected, so a newer one replaces its predecessor.
+        const last = input.at(-1)
+        if (last !== undefined && "type" in last && last.type === "configuration_update") input.pop()
+        input.push({ type: "configuration_update", reasoning: { effort: update.effort ?? DEFAULT_EFFORT } })
+        continue
+      }
       input.push({
         role: "developer",
         content: ProviderShared.joinText(yield* ProviderShared.systemUpdateText(adapter.name, message)),
@@ -789,8 +808,7 @@ export const lowerConversation = Effect.fn("OpenResponses.lowerConversation")(fu
   }
 })
 
-export const lowerGeneration = (request: LLMRequest) => {
-  const options = OpenResponsesOptions.resolve(request)
+export const lowerGeneration = (request: LLMRequest, options = OpenResponsesOptions.resolve(request)) => {
   const generation = request.generation
   const cacheKey = ProviderShared.promptCacheKey(request)
   const parallelToolCalls = resolveParallelToolCalls(request)

packages/ai/src/protocols/openai-responses.ts

@@ -6,7 +6,9 @@ import { Endpoint } from "../route/endpoint.js"
 import { Protocol } from "../route/protocol.js"
 import { HttpTransport } from "../route/transport/index.js"
 import { LLMRequest, mergeJsonRecords, type JsonSchema, type ToolDefinition, type ToolEntry } from "../schema/index.js"
+import { resolveEffortUpdates } from "../effort-updates.js"
 import { OpenResponses } from "./open-responses.js"
+import { OpenResponsesOptions } from "./utils/open-responses-options.js"
 import { JsonObject, optionalArray, optionalNull, ProviderShared } from "./shared.js"
 import { OpenAIImage } from "./utils/openai-image.js"
 import { ResponsesHostedTools } from "./utils/responses-hosted-tools.js"
@@ -94,9 +96,15 @@ const OpenAIResponsesToolChoice = Schema.Union([
   Schema.Struct({ type: Schema.tag("image_generation") }),
 ])
 
+const OpenAIResponsesInputItem = Schema.Union([
+  OpenResponses.InputItem,
+  OpenAIResponsesHostedToolItem,
+  OpenResponses.ConfigurationUpdate,
+])
+
 const OpenAIResponsesCoreFields = {
   ...OpenResponses.coreFields,
-  input: Schema.Array(Schema.Union([OpenResponses.InputItem, OpenAIResponsesHostedToolItem])),
+  input: Schema.Array(OpenAIResponsesInputItem),
   tools: optionalArray(OpenAIResponsesTools),
   tool_choice: Schema.optional(OpenAIResponsesToolChoice),
   context_management: Schema.optional(
@@ -119,7 +127,7 @@ export type OpenAIResponsesBody = Schema.Schema.Type<typeof OpenAIResponsesBody>
 export const CompactionTrigger = Schema.Struct({ type: Schema.Literal("compaction_trigger") })
 const CheckpointBody = Schema.Struct({
   ...OpenAIResponsesBody.fields,
-  input: Schema.Array(Schema.Union([OpenResponses.InputItem, OpenAIResponsesHostedToolItem, CompactionTrigger])),
+  input: Schema.Array(Schema.Union([OpenAIResponsesInputItem, CompactionTrigger])),
   store: Schema.Literal(false),
   prompt_cache_retention: optionalNull(Schema.String),
   prompt_cache_options: optionalNull(
@@ -133,6 +141,14 @@ const adapter = {
   restoreHostedToolItem: (item: unknown) => (Schema.is(OpenAIResponsesHostedToolItem)(item) ? item : undefined),
 } satisfies OpenResponses.ProviderAdapter
 
+// Only GPT-6 Astra accepts `configuration_update`, and never alongside automatic `context_management` compaction.
+const supportsEffortUpdates = (request: LLMRequest) => {
+  if (request.providerOptions?.contextManagement !== undefined) return false
+  const override = request.model.compatibility?.supportsEffortUpdates
+  if (override !== undefined) return override
+  return /(?:^|\/)gpt-6-astra$/i.test(request.model.id)
+}
+
 const nativeImageToolInput = (tool: ToolDefinition) => {
   const native = tool.native?.openai
   return ProviderShared.isRecord(native) && native.type === "image_generation" ? native : undefined
@@ -189,10 +205,12 @@ const fromRequest = Effect.fn("OpenAIResponses.fromRequest")(function* (request:
   const management = yield* ProviderShared.validateWith(
     Schema.decodeUnknownEffect(Schema.UndefinedOr(ContextManagement)),
   )(request.providerOptions?.contextManagement)
+  const options = OpenResponsesOptions.resolve(request)
+  const updates = resolveEffortUpdates(request, options.reasoningEffort)
   const toolSchemaCompatibility = request.model.compatibility?.toolSchema
   return yield* decodeBody({
-    ...(yield* OpenResponses.lowerConversation(request, adapter)),
-    ...OpenResponses.lowerGeneration(request),
+    ...(yield* OpenResponses.lowerConversation(updates.request, adapter)),
+    ...OpenResponses.lowerGeneration(request, { ...options, reasoningEffort: updates.effort }),
     context_management: management?.map((edit) => ({ type: edit.type, compact_threshold: edit.compactThreshold })),
     tools:
       request.tools.length === 0
@@ -295,6 +313,7 @@ export const protocol = Protocol.make({
     step,
     terminal: OpenResponses.terminal,
   },
+  supportsEffortUpdates,
 })
 
 const endpoint = Endpoint.path<OpenAIResponsesBody>(PATH, { baseURL: DEFAULT_BASE_URL })

packages/ai/src/protocols/utils/open-responses-options.ts

@@ -1,12 +1,7 @@
 import { Option, Schema } from "effect"
-import type { LLMRequest } from "../../schema/index.js"
+import { ReasoningEffort, ReasoningEfforts, type LLMRequest } from "../../schema/index.js"
 
-export const ReasoningEfforts = ["none", "minimal", "low", "medium", "high", "xhigh", "max"] as const
-export type ReasoningEffort = (typeof ReasoningEfforts)[number] | (string & {})
-export const ReasoningEffort = Schema.declare<ReasoningEffort>(
-  (value): value is ReasoningEffort => typeof value === "string",
-  { title: "ReasoningEffort" },
-)
+export { ReasoningEffort, ReasoningEfforts }
 
 export const TextVerbosities = ["low", "medium", "high"] as const
 export type TextVerbosity = (typeof TextVerbosities)[number] | (string & {})

packages/ai/src/protocols/utils/responses-compaction.ts

@@ -11,6 +11,7 @@ import {
   mergeJsonRecords,
 } from "../../schema/index.js"
 import type { CompactOperation } from "../../route/client.js"
+import { stripEffortUpdates } from "../../effort-updates.js"
 import { Endpoint } from "../../route/endpoint.js"
 import { RequestExecutor } from "../../route/executor.js"
 import { HttpTransport } from "../../route/transport/index.js"
@@ -75,7 +76,8 @@ const Response = Schema.Struct({
 export const make = (adapter: OpenResponses.ProviderAdapter): CompactOperation =>
   Effect.fn("ResponsesCompaction.execute")(function* (request, executor, options) {
     const route = request.model.route
-    const native = yield* OpenResponses.lowerConversation(request, adapter)
+    // The standalone compaction endpoint rejects histories containing configuration updates.
+    const native = yield* OpenResponses.lowerConversation(stripEffortUpdates(request), adapter)
     const body = yield* ProviderShared.validateWith(Schema.decodeUnknownEffect(Body))(
       mergeJsonRecords(
         {

packages/ai/src/provider-package.ts

@@ -1,10 +1,6 @@
 import type { LanguageModel, ProviderOptions } from "./schema/index.js"
 import type { CompactionOperations } from "./route/client.js"
 
-/**
- * Flat, serializable settings for `model(modelID, settings)`. Each entrypoint declares the connection keys it
- * reads; every other key is a request option for the route's protocol.
- */
 export interface Settings extends Readonly<Record<string, unknown>> {
   readonly baseURL?: string
   readonly headers?: Readonly<Record<string, string>>

packages/ai/src/providers/alibaba.ts

@@ -1,4 +1,3 @@
-import { Struct } from "effect"
 import type { ProviderPackage } from "../provider-package.js"
 import { AlibabaChat } from "../protocols/alibaba-chat.js"
 import { AlibabaMessages } from "../protocols/alibaba-messages.js"
@@ -35,9 +34,9 @@ export type Config = Location &
     readonly providerOptions?: ChatOptionsInput | MessagesOptionsInput | ResponsesOptionsInput
   }
 export type Settings<Options = ChatOptionsInput> = Location &
-  ProviderPackage.Settings &
-  Options & {
+  ProviderPackage.Settings & {
     readonly apiKey?: string
+    readonly providerOptions?: Options
   }
 
 const hosts = new Map<string, string>([
@@ -121,11 +120,7 @@ export const responsesModel: ProviderPackage.Definition<
 
 function fromSettings(input: Settings<Config["providerOptions"]>) {
   const { body, ...rest } = input
-  return configure({
-    ...rest,
-    http: body === undefined ? undefined : { body },
-    providerOptions: Struct.omit(rest, ["apiKey", "baseURL", "headers", "region", "workspaceID"]),
-  })
+  return configure({ ...rest, http: body === undefined ? undefined : { body } })
 }
 
 export const webSearch = () => hostedTool("web_search", "Search the web with Alibaba's hosted search tool.")

packages/ai/src/providers/amazon-bedrock-mantle.ts

@@ -23,16 +23,16 @@ export type Config = RouteDefaultsInput & {
   readonly providerOptions?: OpenAIProviderOptionsInput
 }
 
-export type Settings = ProviderPackage.Settings &
-  OpenAIProviderOptionsInput & {
-    readonly apiKey?: string
-    readonly auth?: "bearer" | "sigv4"
-    readonly baseURL?: string
-    readonly credentials?: Credentials
-    readonly profile?: string
-    readonly region?: string
-    readonly topP?: number
-  }
+export interface Settings extends ProviderPackage.Settings {
+  readonly apiKey?: string
+  readonly auth?: "bearer" | "sigv4"
+  readonly baseURL?: string
+  readonly credentials?: Credentials
+  readonly profile?: string
+  readonly region?: string
+  readonly topP?: number
+  readonly providerOptions?: OpenAIProviderOptionsInput
+}
 
 const responsesRoute = Route.make({
   id: "bedrock-mantle-responses",
@@ -108,29 +108,18 @@ export const configure = (input: Config = {}) => {
 
 export const provider = configure()
 
-const fromSettings = ({
-  apiKey,
-  auth,
-  baseURL,
-  body,
-  credentials,
-  headers,
-  profile,
-  region,
-  topP,
-  ...providerOptions
-}: Settings) =>
+const fromSettings = (settings: Settings) =>
   configure({
-    apiKey,
-    auth,
-    baseURL,
-    credentials,
-    generation: topP === undefined ? undefined : { topP },
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    profile,
-    providerOptions,
-    region,
+    apiKey: settings.apiKey,
+    auth: settings.auth,
+    baseURL: settings.baseURL,
+    credentials: settings.credentials,
+    generation: settings.topP === undefined ? undefined : { topP: settings.topP },
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    profile: settings.profile,
+    providerOptions: settings.providerOptions,
+    region: settings.region,
   })
 
 export const chatModel: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (

packages/ai/src/providers/anthropic-compatible.ts

@@ -19,13 +19,13 @@ export type Config = RouteDefaultsInput &
   }
 
 export type Settings = ProviderPackage.Settings &
-  AnthropicMessages.ProviderOptionsInput &
   (
     | { readonly apiKey?: string; readonly authToken?: never }
     | { readonly apiKey?: never; readonly authToken?: string }
   ) & {
     readonly baseURL: string
     readonly provider?: string
+    readonly providerOptions?: AnthropicMessages.ProviderOptionsInput
   }
 
 export const routes = [AnthropicMessages.route]
@@ -63,20 +63,22 @@ export const provider = {
 
 export const model: ProviderPackage.Definition<Settings, AnthropicMessages.ProviderOptionsInput>["model"] = (
   modelID,
-  { apiKey, authToken, baseURL, body, headers, provider, ...providerOptions },
+  settings,
 ) => {
-  if (apiKey !== undefined && authToken !== undefined)
+  // Read before the exclusivity check narrows a conflicting settings object to `never`.
+  const provider = ProviderID.make(settings.provider ?? id)
+  if (settings.apiKey !== undefined && settings.authToken !== undefined)
     throw new ProviderConfigurationError({
-      provider: ProviderID.make(provider ?? id),
+      provider,
       message: "Anthropic-compatible apiKey cannot be combined with authToken",
     })
   return configure({
-    ...(authToken === undefined ? { apiKey: apiKey } : { auth: Auth.bearer(authToken) }),
-    baseURL,
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    provider,
-    providerOptions,
+    ...(settings.authToken === undefined ? { apiKey: settings.apiKey } : { auth: Auth.bearer(settings.authToken) }),
+    baseURL: settings.baseURL,
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    provider: settings.provider,
+    providerOptions: settings.providerOptions,
   }).model(modelID)
 }
 

packages/ai/src/providers/anthropic.ts

@@ -21,12 +21,12 @@ export type Config = RouteDefaultsInput &
   }
 
 export type Settings = ProviderPackage.Settings &
-  AnthropicMessages.ProviderOptionsInput &
   (
     | { readonly apiKey?: string; readonly authToken?: never }
     | { readonly apiKey?: never; readonly authToken?: string }
   ) & {
     readonly baseURL?: string
+    readonly providerOptions?: AnthropicMessages.ProviderOptionsInput
   }
 
 const auth = (options: ProviderAuthOption<"optional">) => {
@@ -54,18 +54,18 @@ export const configure = (input: Config = {}) => {
 export const provider = configure()
 export const model: ProviderPackage.Definition<Settings, AnthropicMessages.ProviderOptionsInput>["model"] = (
   modelID,
-  { apiKey, authToken, baseURL, body, headers, ...providerOptions },
+  settings,
 ) => {
-  if (apiKey !== undefined && authToken !== undefined)
+  if (settings.apiKey !== undefined && settings.authToken !== undefined)
     throw new ProviderConfigurationError({
       provider: id,
       message: "Anthropic apiKey cannot be combined with authToken",
     })
   return configure({
-    ...(authToken === undefined ? { apiKey: apiKey } : { auth: Auth.bearer(authToken) }),
-    baseURL,
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    ...(settings.authToken === undefined ? { apiKey: settings.apiKey } : { auth: Auth.bearer(settings.authToken) }),
+    baseURL: settings.baseURL,
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).model(modelID)
 }

packages/ai/src/providers/azure.ts

@@ -28,12 +28,12 @@ export type LanguageModelOptions = AzureURL &
 export type Config = LanguageModelOptions
 
 export type Settings = ProviderPackage.Settings &
-  OpenAIProviderOptionsInput &
   AzureURL & {
     readonly apiKey?: string
     readonly apiVersion?: string
     readonly queryParams?: Readonly<Record<string, string>>
     readonly useDeploymentBasedUrls?: boolean
+    readonly providerOptions?: OpenAIProviderOptionsInput
   }
 
 const resourceBaseURL = (resourceName: string) => `https://${resourceName.trim()}.openai.azure.com/openai`
@@ -151,28 +151,18 @@ export const provider = {
   configure,
 }
 
-const config = ({
-  apiKey,
-  apiVersion,
-  baseURL,
-  body,
-  headers,
-  queryParams,
-  resourceName,
-  useDeploymentBasedUrls,
-  ...providerOptions
-}: Settings): Config => {
+const config = (settings: Settings): Config => {
   const common = {
-    apiKey,
-    apiVersion,
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
-    queryParams: queryParams === undefined ? undefined : { ...queryParams },
-    useDeploymentBasedUrls,
+    apiKey: settings.apiKey,
+    apiVersion: settings.apiVersion,
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
+    queryParams: settings.queryParams === undefined ? undefined : { ...settings.queryParams },
+    useDeploymentBasedUrls: settings.useDeploymentBasedUrls,
   }
-  if (baseURL !== undefined) return { ...common, baseURL }
-  if (resourceName !== undefined) return { ...common, resourceName }
+  if (settings.baseURL !== undefined) return { ...common, baseURL: settings.baseURL }
+  if (settings.resourceName !== undefined) return { ...common, resourceName: settings.resourceName }
   throw new ProviderConfigurationError({ provider: id, message: "Azure requires resourceName or baseURL" })
 }
 

packages/ai/src/providers/baseten.ts

@@ -15,11 +15,11 @@ export type LanguageModelOptions = Omit<RouteDefaultsInput, "providerOptions"> &
     readonly providerOptions?: OpenAIProviderOptionsInput
   }
 
-export type Settings = ProviderPackage.Settings &
-  OpenAIProviderOptionsInput & {
-    readonly apiKey?: string
-    readonly baseURL?: string
-  }
+export interface Settings extends ProviderPackage.Settings {
+  readonly apiKey?: string
+  readonly baseURL?: string
+  readonly providerOptions?: OpenAIProviderOptionsInput
+}
 
 export const route = Route.make({
   id: "baseten-chat",
@@ -48,16 +48,13 @@ export const configure = (input: LanguageModelOptions = {}) => {
 
 export const provider = configure()
 
-export const model: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (
-  modelID,
-  { apiKey, baseURL, body, headers, ...providerOptions },
-) =>
+export const model: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (modelID, settings) =>
   configure({
-    apiKey,
-    baseURL,
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).model(modelID)
 
 export * as Baseten from "./baseten.js"

packages/ai/src/providers/cerebras.ts

@@ -15,11 +15,11 @@ export type LanguageModelOptions = Omit<RouteDefaultsInput, "providerOptions"> &
     readonly providerOptions?: OpenAIProviderOptionsInput
   }
 
-export type Settings = ProviderPackage.Settings &
-  OpenAIProviderOptionsInput & {
-    readonly apiKey?: string
-    readonly baseURL?: string
-  }
+export interface Settings extends ProviderPackage.Settings {
+  readonly apiKey?: string
+  readonly baseURL?: string
+  readonly providerOptions?: OpenAIProviderOptionsInput
+}
 
 export const route = Route.make({
   id: "cerebras-chat",
@@ -52,14 +52,11 @@ export const configure = (input: LanguageModelOptions = {}) => {
 
 export const provider = configure()
 
-export const model: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (
-  modelID,
-  { apiKey, baseURL, body, headers, ...providerOptions },
-) =>
+export const model: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (modelID, settings) =>
   configure({
-    apiKey,
-    baseURL,
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).model(modelID)

packages/ai/src/providers/cloudflare-ai-gateway.ts

@@ -27,10 +27,10 @@ export type LanguageModelOptions = GatewayURL &
   }
 
 export type Settings = ProviderPackage.Settings &
-  OpenAIProviderOptionsInput &
   GatewayURL & {
     readonly apiKey?: string
     readonly gatewayApiKey?: string
+    readonly providerOptions?: OpenAIProviderOptionsInput
   }
 
 export const baseURL = (input: GatewayURL) => {
@@ -89,25 +89,14 @@ export const configure = (input: LanguageModelOptions) => {
 
 export const provider = { id, configure }
 
-export const model: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (modelID, settings) => {
-  const {
-    accountId: _,
-    apiKey,
-    baseURL: _url,
-    body,
-    gatewayApiKey,
-    gatewayId: _id,
-    headers,
-    ...providerOptions
-  } = settings
-  return configure({
-    apiKey,
-    gatewayApiKey,
+export const model: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (modelID, settings) =>
+  configure({
+    apiKey: settings.apiKey,
+    gatewayApiKey: settings.gatewayApiKey,
     baseURL: baseURL(settings),
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).model(modelID)
-}
 
 export * as CloudflareAIGateway from "./cloudflare-ai-gateway.js"

packages/ai/src/providers/cloudflare-workers-ai.ts

@@ -21,9 +21,9 @@ export type LanguageModelOptions = WorkersAIURL &
   }
 
 export type Settings = ProviderPackage.Settings &
-  OpenAIProviderOptionsInput &
   WorkersAIURL & {
     readonly apiKey?: string
+    readonly providerOptions?: OpenAIProviderOptionsInput
   }
 
 export const baseURL = (input: WorkersAIURL) => {
@@ -63,15 +63,13 @@ export const configure = (input: LanguageModelOptions) => {
 
 export const provider = { id, configure }
 
-export const model: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (modelID, settings) => {
-  const { accountId: _, apiKey, baseURL: _url, body, headers, ...providerOptions } = settings
-  return configure({
-    apiKey,
+export const model: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (modelID, settings) =>
+  configure({
+    apiKey: settings.apiKey,
     baseURL: baseURL(settings),
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).model(modelID)
-}
 
 export * as CloudflareWorkersAI from "./cloudflare-workers-ai.js"

packages/ai/src/providers/deepinfra.ts

@@ -15,11 +15,11 @@ export type LanguageModelOptions = Omit<RouteDefaultsInput, "providerOptions"> &
     readonly providerOptions?: OpenAIProviderOptionsInput
   }
 
-export type Settings = ProviderPackage.Settings &
-  OpenAIProviderOptionsInput & {
-    readonly apiKey?: string
-    readonly baseURL?: string
-  }
+export interface Settings extends ProviderPackage.Settings {
+  readonly apiKey?: string
+  readonly baseURL?: string
+  readonly providerOptions?: OpenAIProviderOptionsInput
+}
 
 export const route = Route.make({
   id: "deepinfra-chat",
@@ -55,14 +55,11 @@ export const configure = (input: LanguageModelOptions = {}) => {
 
 export const provider = configure()
 
-export const model: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (
-  modelID,
-  { apiKey, baseURL, body, headers, ...providerOptions },
-) =>
+export const model: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (modelID, settings) =>
   configure({
-    apiKey,
-    baseURL,
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).model(modelID)

packages/ai/src/providers/deepseek.ts

@@ -15,11 +15,11 @@ export type LanguageModelOptions = Omit<RouteDefaultsInput, "providerOptions"> &
     readonly providerOptions?: OpenAIProviderOptionsInput
   }
 
-export type Settings = ProviderPackage.Settings &
-  OpenAIProviderOptionsInput & {
-    readonly apiKey?: string
-    readonly baseURL?: string
-  }
+export interface Settings extends ProviderPackage.Settings {
+  readonly apiKey?: string
+  readonly baseURL?: string
+  readonly providerOptions?: OpenAIProviderOptionsInput
+}
 
 export const route = Route.make({
   id: "deepseek-chat",
@@ -52,16 +52,13 @@ export const configure = (input: LanguageModelOptions = {}) => {
 
 export const provider = configure()
 
-export const model: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (
-  modelID,
-  { apiKey, baseURL, body, headers, ...providerOptions },
-) =>
+export const model: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (modelID, settings) =>
   configure({
-    apiKey,
-    baseURL,
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).model(modelID)
 
 export * as DeepSeek from "./deepseek.js"

packages/ai/src/providers/fireworks.ts

@@ -15,11 +15,11 @@ export type LanguageModelOptions = Omit<RouteDefaultsInput, "providerOptions"> &
     readonly providerOptions?: OpenAIProviderOptionsInput
   }
 
-export type Settings = ProviderPackage.Settings &
-  OpenAIProviderOptionsInput & {
-    readonly apiKey?: string
-    readonly baseURL?: string
-  }
+export interface Settings extends ProviderPackage.Settings {
+  readonly apiKey?: string
+  readonly baseURL?: string
+  readonly providerOptions?: OpenAIProviderOptionsInput
+}
 
 export const route = Route.make({
   id: "fireworks-chat",
@@ -48,16 +48,13 @@ export const configure = (input: LanguageModelOptions = {}) => {
 
 export const provider = configure()
 
-export const model: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (
-  modelID,
-  { apiKey, baseURL, body, headers, ...providerOptions },
-) =>
+export const model: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (modelID, settings) =>
   configure({
-    apiKey,
-    baseURL,
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).model(modelID)
 
 export * as Fireworks from "./fireworks.js"

packages/ai/src/providers/google-vertex-chat.ts

@@ -16,14 +16,14 @@ export type Config = RouteDefaultsInput &
     readonly providerOptions?: OpenAIProviderOptionsInput
   }
 
-export type Settings = ProviderPackage.Settings &
-  OpenAIProviderOptionsInput & {
-    readonly accessToken?: string
-    readonly apiKey?: never
-    readonly baseURL?: string
-    readonly location?: string
-    readonly project?: string
-  }
+export interface Settings extends ProviderPackage.Settings {
+  readonly accessToken?: string
+  readonly apiKey?: never
+  readonly baseURL?: string
+  readonly location?: string
+  readonly project?: string
+  readonly providerOptions?: OpenAIProviderOptionsInput
+}
 
 const route = Route.make({
   id: "google-vertex-chat",
@@ -74,19 +74,16 @@ export const provider = {
   configure,
 }
 
-export const model: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (
-  modelID,
-  { accessToken, apiKey, baseURL, body, headers, location, project, ...providerOptions },
-) => {
-  if (apiKey !== undefined)
+export const model: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (modelID, settings) => {
+  if (settings.apiKey !== undefined)
     throw new ProviderConfigurationError({ provider: id, message: "Google Vertex Chat does not support API keys" })
   return configure({
-    accessToken,
-    baseURL,
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    location,
-    project,
-    providerOptions,
+    accessToken: settings.accessToken,
+    baseURL: settings.baseURL,
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    location: settings.location,
+    project: settings.project,
+    providerOptions: settings.providerOptions,
   }).model(modelID)
 }

packages/ai/src/providers/google-vertex-messages.ts

@@ -25,14 +25,14 @@ export type Config = RouteDefaultsInput &
     readonly providerOptions?: AnthropicMessages.ProviderOptionsInput
   }
 
-export type Settings = ProviderPackage.Settings &
-  AnthropicMessages.ProviderOptionsInput & {
-    readonly accessToken?: string
-    readonly apiKey?: never
-    readonly baseURL?: string
-    readonly location?: string
-    readonly project?: string
-  }
+export interface Settings extends ProviderPackage.Settings {
+  readonly accessToken?: string
+  readonly apiKey?: never
+  readonly baseURL?: string
+  readonly location?: string
+  readonly project?: string
+  readonly providerOptions?: AnthropicMessages.ProviderOptionsInput
+}
 
 const route = Route.make({
   id: "google-vertex-messages",
@@ -105,17 +105,17 @@ export const provider = {
 
 export const model: ProviderPackage.Definition<Settings, AnthropicMessages.ProviderOptionsInput>["model"] = (
   modelID,
-  { accessToken, apiKey, baseURL, body, headers, location, project, ...providerOptions },
+  settings,
 ) => {
-  if (apiKey !== undefined)
+  if (settings.apiKey !== undefined)
     throw new ProviderConfigurationError({ provider: id, message: "Google Vertex Messages does not support API keys" })
   return configure({
-    accessToken,
-    baseURL,
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    location,
-    project,
-    providerOptions,
+    accessToken: settings.accessToken,
+    baseURL: settings.baseURL,
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    location: settings.location,
+    project: settings.project,
+    providerOptions: settings.providerOptions,
   }).model(modelID)
 }

packages/ai/src/providers/google-vertex-responses.ts

@@ -16,14 +16,14 @@ export type Config = RouteDefaultsInput &
     readonly providerOptions?: OpenResponsesProviderOptionsInput
   }
 
-export type Settings = ProviderPackage.Settings &
-  OpenResponsesProviderOptionsInput & {
-    readonly accessToken?: string
-    readonly apiKey?: never
-    readonly baseURL?: string
-    readonly location?: string
-    readonly project?: string
-  }
+export interface Settings extends ProviderPackage.Settings {
+  readonly accessToken?: string
+  readonly apiKey?: never
+  readonly baseURL?: string
+  readonly location?: string
+  readonly project?: string
+  readonly providerOptions?: OpenResponsesProviderOptionsInput
+}
 
 const route = Route.make({
   id: "google-vertex-responses",
@@ -77,17 +77,17 @@ export const provider = {
 
 export const model: ProviderPackage.Definition<Settings, OpenResponsesProviderOptionsInput>["model"] = (
   modelID,
-  { accessToken, apiKey, baseURL, body, headers, location, project, ...providerOptions },
+  settings,
 ) => {
-  if (apiKey !== undefined)
+  if (settings.apiKey !== undefined)
     throw new ProviderConfigurationError({ provider: id, message: "Google Vertex Responses does not support API keys" })
   return configure({
-    accessToken,
-    baseURL,
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    location,
-    project,
-    providerOptions,
+    accessToken: settings.accessToken,
+    baseURL: settings.baseURL,
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    location: settings.location,
+    project: settings.project,
+    providerOptions: settings.providerOptions,
   }).model(modelID)
 }

packages/ai/src/providers/google-vertex.ts

@@ -26,7 +26,6 @@ export type Config = RouteDefaultsInput &
   }
 
 export type Settings = ProviderPackage.Settings &
-  GeminiProviderOptionsInput &
   (
     | { readonly accessToken?: string; readonly apiKey?: never }
     | { readonly accessToken?: never; readonly apiKey?: string }
@@ -34,6 +33,7 @@ export type Settings = ProviderPackage.Settings &
     readonly baseURL?: string
     readonly location?: string
     readonly project?: string
+    readonly providerOptions?: GeminiProviderOptionsInput
   }
 
 const fromRequest = Effect.fn("GoogleVertex.fromRequest")(function* (request: LLMRequest) {
@@ -124,22 +124,19 @@ export const provider = {
   id,
   configure,
 }
-export const model: ProviderPackage.Definition<Settings, GeminiProviderOptionsInput>["model"] = (
-  modelID,
-  { accessToken, apiKey, baseURL, body, headers, location, project, ...providerOptions },
-) => {
-  if (apiKey !== undefined && accessToken !== undefined)
+export const model: ProviderPackage.Definition<Settings, GeminiProviderOptionsInput>["model"] = (modelID, settings) => {
+  if (settings.apiKey !== undefined && settings.accessToken !== undefined)
     throw new ProviderConfigurationError({
       provider: id,
       message: "Google Vertex apiKey cannot be combined with accessToken or auth",
     })
   return configure({
-    ...(apiKey === undefined ? { accessToken: accessToken } : { apiKey: apiKey }),
-    baseURL,
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    location,
-    project,
-    providerOptions,
+    ...(settings.apiKey === undefined ? { accessToken: settings.accessToken } : { apiKey: settings.apiKey }),
+    baseURL: settings.baseURL,
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    location: settings.location,
+    project: settings.project,
+    providerOptions: settings.providerOptions,
   }).model(modelID)
 }

packages/ai/src/providers/google.ts

@@ -20,11 +20,11 @@ export type Config = RouteDefaultsInput &
     readonly providerOptions?: Gemini.ProviderOptionsInput
   }
 
-export type Settings = ProviderPackage.Settings &
-  Gemini.ProviderOptionsInput & {
-    readonly apiKey?: string
-    readonly baseURL?: string
-  }
+export interface Settings extends ProviderPackage.Settings {
+  readonly apiKey?: string
+  readonly baseURL?: string
+  readonly providerOptions?: Gemini.ProviderOptionsInput
+}
 
 const auth = (options: ProviderAuthOption<"optional">) => {
   if ("auth" in options && options.auth) return options.auth
@@ -57,16 +57,13 @@ export const configure = (input: Config = {}) => {
 }
 
 export const provider = configure()
-export const model: ProviderPackage.Definition<Settings, Gemini.ProviderOptionsInput>["model"] = (
-  modelID,
-  { apiKey, baseURL, body, headers, ...providerOptions },
-) =>
+export const model: ProviderPackage.Definition<Settings, Gemini.ProviderOptionsInput>["model"] = (modelID, settings) =>
   configure({
-    apiKey,
-    baseURL,
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).model(modelID)
 
 export const image = provider.image

packages/ai/src/providers/groq.ts

@@ -26,11 +26,11 @@ export type LanguageModelOptions = Omit<RouteDefaultsInput, "providerOptions"> &
     readonly providerOptions?: ProviderOptions
   }
 
-export type Settings = ProviderPackage.Settings &
-  ProviderOptions & {
-    readonly apiKey?: string
-    readonly baseURL?: string
-  }
+export interface Settings extends ProviderPackage.Settings {
+  readonly apiKey?: string
+  readonly baseURL?: string
+  readonly providerOptions?: ProviderOptions
+}
 
 const Options = Schema.Struct({
   includeReasoning: Schema.optional(Schema.Boolean),
@@ -103,16 +103,13 @@ export const configure = (input: LanguageModelOptions = {}) => {
 
 export const provider = configure()
 
-export const model: ProviderPackage.Definition<Settings, ProviderOptions>["model"] = (
-  modelID,
-  { apiKey, baseURL, body, headers, ...providerOptions },
-) =>
+export const model: ProviderPackage.Definition<Settings, ProviderOptions>["model"] = (modelID, settings) =>
   configure({
-    apiKey,
-    baseURL,
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).model(modelID)
 
 export * as Groq from "./groq.js"

packages/ai/src/providers/meta.ts

@@ -79,11 +79,11 @@ export type LanguageModelOptions = Omit<RouteDefaultsInput, "providerOptions"> &
     readonly providerOptions?: ProviderOptionsInput
   }
 
-export type Settings = ProviderPackage.Settings &
-  ProviderOptionsInput & {
-    readonly apiKey?: string
-    readonly baseURL?: string
-  }
+export interface Settings extends ProviderPackage.Settings {
+  readonly apiKey?: string
+  readonly baseURL?: string
+  readonly providerOptions?: ProviderOptionsInput
+}
 
 const responsesRoute = Route.make({
   id: "meta-responses",
@@ -169,13 +169,13 @@ export const chatModel: ProviderPackage.Definition<Settings, OpenResponsesProvid
 export const messagesModel: ProviderPackage.Definition<Settings, MessagesOptionsInput>["model"] = (modelID, settings) =>
   fromSettings(settings).messages(modelID)
 
-function fromSettings({ apiKey, baseURL, body, headers, ...providerOptions }: Settings) {
+function fromSettings(settings: Settings) {
   return configure({
-    apiKey,
-    baseURL,
-    headers,
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers,
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   })
 }
 

packages/ai/src/providers/minimax.ts

@@ -40,11 +40,11 @@ export type Config = Omit<RouteDefaultsInput, "providerOptions"> &
     readonly providerOptions?: ProviderOptionsInput
   }
 
-export type Settings<Options = MessagesOptionsInput> = ProviderPackage.Settings &
-  Options & {
-    readonly apiKey?: string
-    readonly baseURL?: string
-  }
+export interface Settings<Options = MessagesOptionsInput> extends ProviderPackage.Settings {
+  readonly apiKey?: string
+  readonly baseURL?: string
+  readonly providerOptions?: Options
+}
 
 const ChatOptions = Schema.Struct({
   thinking: Schema.optional(Schema.Struct({ type: Schema.String })),
@@ -127,14 +127,14 @@ export const provider = configure()
 
 export const model: ProviderPackage.Definition<Settings<MessagesOptionsInput>, MessagesOptionsInput>["model"] = (
   modelID,
-  { apiKey, baseURL, body, headers, ...providerOptions },
+  settings,
 ) =>
   configure({
-    apiKey,
-    baseURL,
-    headers,
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers,
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).model(modelID)
 
 export const messages = provider.messages

packages/ai/src/providers/minimax/chat.ts

@@ -3,14 +3,11 @@ import { MiniMax } from "../minimax.js"
 
 export type Settings = MiniMax.Settings<MiniMax.ChatOptionsInput>
 
-export const model: ProviderPackage.Definition<Settings, MiniMax.ChatOptionsInput>["model"] = (
-  modelID,
-  { apiKey, baseURL, body, headers, ...providerOptions },
-) =>
+export const model: ProviderPackage.Definition<Settings, MiniMax.ChatOptionsInput>["model"] = (modelID, settings) =>
   MiniMax.configure({
-    apiKey,
-    baseURL,
-    headers,
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers,
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).chat(modelID)

packages/ai/src/providers/minimax/responses.ts

@@ -5,12 +5,12 @@ export type Settings = MiniMax.Settings<MiniMax.ResponsesOptionsInput>
 
 export const model: ProviderPackage.Definition<Settings, MiniMax.ResponsesOptionsInput>["model"] = (
   modelID,
-  { apiKey, baseURL, body, headers, ...providerOptions },
+  settings,
 ) =>
   MiniMax.configure({
-    apiKey,
-    baseURL,
-    headers,
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers,
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).responses(modelID)

packages/ai/src/providers/mistral.ts

@@ -14,11 +14,11 @@ export type LanguageModelOptions = Omit<RouteDefaultsInput, "providerOptions"> &
     readonly providerOptions?: ProviderOptions
   }
 
-export type Settings = ProviderPackage.Settings &
-  ProviderOptions & {
-    readonly apiKey?: string
-    readonly baseURL?: string
-  }
+export interface Settings extends ProviderPackage.Settings {
+  readonly apiKey?: string
+  readonly baseURL?: string
+  readonly providerOptions?: ProviderOptions
+}
 
 export const route = MistralChat.route
 export const routes = [route]
@@ -39,16 +39,13 @@ export const configure = (input: LanguageModelOptions = {}) => {
 
 export const provider = configure()
 
-export const model: ProviderPackage.Definition<Settings, ProviderOptions>["model"] = (
-  modelID,
-  { apiKey, baseURL, body, headers, ...providerOptions },
-) =>
+export const model: ProviderPackage.Definition<Settings, ProviderOptions>["model"] = (modelID, settings) =>
   configure({
-    apiKey,
-    baseURL,
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).model(modelID)
 
 export * as Mistral from "./mistral.js"

packages/ai/src/providers/moonshot.ts

@@ -42,11 +42,11 @@ export type Config = Omit<RouteDefaultsInput, "providerOptions"> &
     readonly providerOptions?: ChatOptionsInput | MessagesOptionsInput | ResponsesOptionsInput
   }
 
-export type Settings<Options = ChatOptionsInput> = ProviderPackage.Settings &
-  Options & {
-    readonly apiKey?: string
-    readonly baseURL?: string
-  }
+export interface Settings<Options = ChatOptionsInput> extends ProviderPackage.Settings {
+  readonly apiKey?: string
+  readonly baseURL?: string
+  readonly providerOptions?: Options
+}
 
 const ChatOptions = Schema.Struct({
   reasoningEffort: Schema.optional(Schema.String),
@@ -133,16 +133,13 @@ export const chat = provider.chat
 export const messages = provider.messages
 export const responses = provider.responses
 
-export const model: ProviderPackage.Definition<Settings, ChatOptionsInput>["model"] = (
-  modelID,
-  { apiKey, baseURL, body, headers, ...providerOptions },
-) =>
+export const model: ProviderPackage.Definition<Settings, ChatOptionsInput>["model"] = (modelID, settings) =>
   configure({
-    apiKey,
-    baseURL,
-    headers,
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers,
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).model(modelID)
 
 export * as Moonshot from "./moonshot.js"

packages/ai/src/providers/moonshot/messages.ts

@@ -5,12 +5,12 @@ export type Settings = Moonshot.Settings<Moonshot.MessagesOptionsInput>
 
 export const model: ProviderPackage.Definition<Settings, Moonshot.MessagesOptionsInput>["model"] = (
   modelID,
-  { apiKey, baseURL, body, headers, ...providerOptions },
+  settings,
 ) =>
   Moonshot.configure({
-    apiKey,
-    baseURL,
-    headers,
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers,
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).messages(modelID)

packages/ai/src/providers/moonshot/responses.ts

@@ -5,12 +5,12 @@ export type Settings = Moonshot.Settings<Moonshot.ResponsesOptionsInput>
 
 export const model: ProviderPackage.Definition<Settings, Moonshot.ResponsesOptionsInput>["model"] = (
   modelID,
-  { apiKey, baseURL, body, headers, ...providerOptions },
+  settings,
 ) =>
   Moonshot.configure({
-    apiKey,
-    baseURL,
-    headers,
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers,
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).responses(modelID)

packages/ai/src/providers/openai-compatible-responses.ts

@@ -16,12 +16,12 @@ export type Config = RouteDefaultsInput &
     readonly providerOptions?: OpenResponsesProviderOptionsInput
   }
 
-export type Settings = ProviderPackage.Settings &
-  OpenResponsesProviderOptionsInput & {
-    readonly apiKey?: string
-    readonly baseURL: string
-    readonly provider?: string
-  }
+export interface Settings extends ProviderPackage.Settings {
+  readonly apiKey?: string
+  readonly baseURL: string
+  readonly provider?: string
+  readonly providerOptions?: OpenResponsesProviderOptionsInput
+}
 
 export const routes = [OpenAICompatibleResponses.route]
 
@@ -48,13 +48,13 @@ export const provider = {
 
 export const model: ProviderPackage.Definition<Settings, OpenResponsesProviderOptionsInput>["model"] = (
   modelID,
-  { apiKey, baseURL, body, headers, provider, ...providerOptions },
+  settings,
 ) =>
   configure({
-    apiKey,
-    baseURL,
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    provider,
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    provider: settings.provider,
+    providerOptions: settings.providerOptions,
   }).model(modelID)

packages/ai/src/providers/openai-compatible.ts

@@ -14,12 +14,12 @@ type GenericModelOptions = Omit<RouteDefaultsInput, "providerOptions"> &
     readonly providerOptions?: OpenAIProviderOptionsInput
   }
 
-export type Settings = ProviderPackage.Settings &
-  OpenAIProviderOptionsInput & {
-    readonly apiKey?: string
-    readonly baseURL: string
-    readonly provider?: string
-  }
+export interface Settings extends ProviderPackage.Settings {
+  readonly apiKey?: string
+  readonly baseURL: string
+  readonly provider?: string
+  readonly providerOptions?: OpenAIProviderOptionsInput
+}
 
 export const routes = [OpenAICompatibleChat.route]
 
@@ -45,17 +45,14 @@ export const provider = {
   configure,
 }
 
-export const model: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (
-  modelID,
-  { apiKey, baseURL, body, headers, provider, ...providerOptions },
-) =>
+export const model: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (modelID, settings) =>
   configure({
-    apiKey,
-    baseURL,
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    provider,
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    provider: settings.provider,
+    providerOptions: settings.providerOptions,
   }).model(modelID)
 
 export * as OpenAICompatible from "./openai-compatible.js"

packages/ai/src/providers/openai.ts

@@ -57,14 +57,14 @@ export const imageGeneration = (options: ImageGenerationOptions = {}) =>
     },
   })
 
-export type Settings = ProviderPackage.Settings &
-  OpenAIProviderOptionsInput & {
-    readonly apiKey?: string
-    readonly baseURL?: string
-    readonly organization?: string
-    readonly project?: string
-    readonly queryParams?: Readonly<Record<string, string>>
-  }
+export interface Settings extends ProviderPackage.Settings {
+  readonly apiKey?: string
+  readonly baseURL?: string
+  readonly organization?: string
+  readonly project?: string
+  readonly queryParams?: Readonly<Record<string, string>>
+  readonly providerOptions?: OpenAIProviderOptionsInput
+}
 
 const auth = (options: ProviderAuthOption<"optional">) => AuthOptions.bearer(options, "OPENAI_API_KEY")
 
@@ -116,28 +116,19 @@ export const configure = (input: Config = {}) => {
 
 export const provider = configure()
 
-const config = ({
-  apiKey,
-  baseURL,
-  body,
-  headers: given,
-  organization,
-  project,
-  queryParams,
-  ...providerOptions
-}: Settings): Config => {
+const config = (settings: Settings): Config => {
   const headers = {
-    ...(organization === undefined ? {} : { "OpenAI-Organization": organization }),
-    ...(project === undefined ? {} : { "OpenAI-Project": project }),
-    ...given,
+    ...(settings.organization === undefined ? {} : { "OpenAI-Organization": settings.organization }),
+    ...(settings.project === undefined ? {} : { "OpenAI-Project": settings.project }),
+    ...settings.headers,
   }
   return {
-    apiKey,
-    baseURL,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
     headers: Object.keys(headers).length === 0 ? undefined : headers,
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
-    queryParams: queryParams === undefined ? undefined : { ...queryParams },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
+    queryParams: settings.queryParams === undefined ? undefined : { ...settings.queryParams },
   }
 }
 

packages/ai/src/providers/openrouter.ts

@@ -77,11 +77,11 @@ export type LanguageModelOptions = Omit<RouteDefaultsInput, "providerOptions"> &
     readonly providerOptions?: OpenRouterProviderOptionsInput
   }
 
-export type Settings = ProviderPackage.Settings &
-  OpenRouterProviderOptionsInput & {
-    readonly apiKey?: string
-    readonly baseURL?: string
-  }
+export interface Settings extends ProviderPackage.Settings {
+  readonly apiKey?: string
+  readonly baseURL?: string
+  readonly providerOptions?: OpenRouterProviderOptionsInput
+}
 
 const OpenRouterBody = Schema.StructWithRest(Schema.Struct(OpenAIChat.bodyFields), [
   Schema.Record(Schema.String, Schema.Any),
@@ -191,12 +191,12 @@ export const configure = (input: LanguageModelOptions = {}) => {
 export const provider = configure()
 export const model: ProviderPackage.Definition<Settings, OpenRouterProviderOptionsInput>["model"] = (
   modelID,
-  { apiKey, baseURL, body, headers, ...providerOptions },
+  settings,
 ) =>
   configure({
-    apiKey,
-    baseURL,
-    headers,
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers,
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).model(modelID)

packages/ai/src/providers/togetherai.ts

@@ -15,11 +15,11 @@ export type LanguageModelOptions = Omit<RouteDefaultsInput, "providerOptions"> &
     readonly providerOptions?: OpenAIProviderOptionsInput
   }
 
-export type Settings = ProviderPackage.Settings &
-  OpenAIProviderOptionsInput & {
-    readonly apiKey?: string
-    readonly baseURL?: string
-  }
+export interface Settings extends ProviderPackage.Settings {
+  readonly apiKey?: string
+  readonly baseURL?: string
+  readonly providerOptions?: OpenAIProviderOptionsInput
+}
 
 export const route = Route.make({
   id: "togetherai-chat",
@@ -52,14 +52,11 @@ export const configure = (input: LanguageModelOptions = {}) => {
 
 export const provider = configure()
 
-export const model: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (
-  modelID,
-  { apiKey, baseURL, body, headers, ...providerOptions },
-) =>
+export const model: ProviderPackage.Definition<Settings, OpenAIProviderOptionsInput>["model"] = (modelID, settings) =>
   configure({
-    apiKey,
-    baseURL,
-    headers: headers === undefined ? undefined : { ...headers },
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers === undefined ? undefined : { ...settings.headers },
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).model(modelID)

packages/ai/src/providers/xai.ts

@@ -20,11 +20,11 @@ export type LanguageModelOptions = Omit<RouteDefaultsInput, "providerOptions"> &
     readonly providerOptions?: XAIProviderOptionsInput
   }
 
-export type Settings = ProviderPackage.Settings &
-  XAIProviderOptionsInput & {
-    readonly apiKey?: string
-    readonly baseURL?: string
-  }
+export interface Settings extends ProviderPackage.Settings {
+  readonly apiKey?: string
+  readonly baseURL?: string
+  readonly providerOptions?: XAIProviderOptionsInput
+}
 
 export type { XAIImageOptions } from "../protocols/xai-images.js"
 
@@ -110,13 +110,13 @@ export const model: ProviderPackage.Definition<
   Settings,
   XAIProviderOptionsInput,
   typeof responsesRoute.compact
->["model"] = (modelID, { apiKey, baseURL, body, headers, ...providerOptions }) =>
+>["model"] = (modelID, settings) =>
   configure({
-    apiKey,
-    baseURL,
-    headers,
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers,
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).model(modelID)
 export const responses = provider.responses
 export const chat = provider.chat

packages/ai/src/providers/zai-coding-plan.ts

@@ -23,11 +23,11 @@ export type Config = Omit<RouteDefaultsInput, "providerOptions"> &
     readonly providerOptions?: ChatOptionsInput | MessagesOptionsInput | ResponsesOptionsInput
   }
 
-export type Settings<Options = ChatOptionsInput> = ProviderPackage.Settings &
-  Options & {
-    readonly apiKey?: string
-    readonly baseURL?: string
-  }
+export interface Settings<Options = ChatOptionsInput> extends ProviderPackage.Settings {
+  readonly apiKey?: string
+  readonly baseURL?: string
+  readonly providerOptions?: Options
+}
 
 const chatRoute = Route.make({
   id: "zai-coding-chat",
@@ -80,16 +80,13 @@ export const chat = provider.chat
 export const messages = provider.messages
 export const responses = provider.responses
 
-export const model: ProviderPackage.Definition<Settings, ChatOptionsInput>["model"] = (
-  modelID,
-  { apiKey, baseURL, body, headers, ...providerOptions },
-) =>
+export const model: ProviderPackage.Definition<Settings, ChatOptionsInput>["model"] = (modelID, settings) =>
   configure({
-    apiKey,
-    baseURL,
-    headers,
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers,
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).model(modelID)
 
 export * as ZAICodingPlan from "./zai-coding-plan.js"

packages/ai/src/providers/zai-coding-plan/messages.ts

@@ -5,12 +5,12 @@ export type Settings = ZAICodingPlan.Settings<ZAICodingPlan.MessagesOptionsInput
 
 export const model: ProviderPackage.Definition<Settings, ZAICodingPlan.MessagesOptionsInput>["model"] = (
   modelID,
-  { apiKey, baseURL, body, headers, ...providerOptions },
+  settings,
 ) =>
   ZAICodingPlan.configure({
-    apiKey,
-    baseURL,
-    headers,
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers,
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).messages(modelID)

packages/ai/src/providers/zai-coding-plan/responses.ts

@@ -5,12 +5,12 @@ export type Settings = ZAICodingPlan.Settings<ZAICodingPlan.ResponsesOptionsInpu
 
 export const model: ProviderPackage.Definition<Settings, ZAICodingPlan.ResponsesOptionsInput>["model"] = (
   modelID,
-  { apiKey, baseURL, body, headers, ...providerOptions },
+  settings,
 ) =>
   ZAICodingPlan.configure({
-    apiKey,
-    baseURL,
-    headers,
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers,
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).responses(modelID)

packages/ai/src/providers/zai.ts

@@ -17,11 +17,11 @@ export type Config = Omit<RouteDefaultsInput, "providerOptions"> &
     readonly providerOptions?: ChatOptionsInput
   }
 
-export type Settings = ProviderPackage.Settings &
-  ChatOptionsInput & {
-    readonly apiKey?: string
-    readonly baseURL?: string
-  }
+export interface Settings extends ProviderPackage.Settings {
+  readonly apiKey?: string
+  readonly baseURL?: string
+  readonly providerOptions?: ChatOptionsInput
+}
 
 export type { ZAIImageOptions } from "../protocols/zai-images.js"
 
@@ -70,16 +70,13 @@ export const provider = configure()
 export const image = provider.image
 export const chat = provider.chat
 
-export const model: ProviderPackage.Definition<Settings, ChatOptionsInput>["model"] = (
-  modelID,
-  { apiKey, baseURL, body, headers, ...providerOptions },
-) =>
+export const model: ProviderPackage.Definition<Settings, ChatOptionsInput>["model"] = (modelID, settings) =>
   configure({
-    apiKey,
-    baseURL,
-    headers,
-    http: body === undefined ? undefined : { body: { ...body } },
-    providerOptions,
+    apiKey: settings.apiKey,
+    baseURL: settings.baseURL,
+    headers: settings.headers,
+    http: settings.body === undefined ? undefined : { body: { ...settings.body } },
+    providerOptions: settings.providerOptions,
   }).model(modelID)
 
 export * as ZAI from "./zai.js"

packages/ai/src/route/client.ts

@@ -7,6 +7,7 @@ import { HttpTransport } from "./transport/index.js"
 import type { HttpMiddleware, Transport, TransportRuntime, WebSocketChannelExecutor } from "./transport/index.js"
 import type { Protocol } from "./protocol.js"
 import { applyCachePolicy } from "../cache-policy.js"
+import { applyEffortUpdates } from "../effort-updates.js"
 import { normalizeToolHistory } from "../tool-history.js"
 import { sanitizeSurrogates } from "../utils/sanitize.js"
 import * as ProviderShared from "../protocols/shared.js"
@@ -55,6 +56,7 @@ export interface Route<
   readonly transport: Transport<Body, Prepared, unknown>
   readonly defaults: RouteDefaults
   readonly body: RouteBody<Body>
+  readonly supportsEffortUpdates?: (request: LLMRequest) => boolean
   readonly with: {
     <Next extends CompactionOperations | undefined>(
       patch: RoutePatch<Body, Prepared> & { readonly compact: Next },
@@ -388,6 +390,7 @@ function makeFromTransport<Body, Prepared, Frame, Event, State>(
       transport: routeInput.transport,
       defaults: routeInput.defaults ?? {},
       body: protocol.body,
+      supportsEffortUpdates: protocol.supportsEffortUpdates,
       with: (patch: RoutePatch<Body, Prepared>) => {
         const { compact, id, provider, providerMetadataKey, auth, transport, endpoint, ...defaults } = patch
         return build({
@@ -558,7 +561,9 @@ const prepareRequest = (request: LLMRequest) => {
     [...new Map(tools.map((tool) => [`${tool.type}:${tool.name}`, tool])).values()].map((tool) =>
       tool.type === "tool" ? tool : { ...tool, tools: dedupe(tool.tools) },
     )
-  const resolved = applyCachePolicy(LLMRequest.update(sanitized, { tools: dedupe(sanitized.tools) }))
+  const resolved = applyCachePolicy(
+    applyEffortUpdates(LLMRequest.update(sanitized, { tools: dedupe(sanitized.tools) })),
+  )
   const headers = resolved.model.route.headers?.({ request: resolved })
   return headers === undefined
     ? resolved

packages/ai/src/route/protocol.ts

@@ -41,6 +41,8 @@ export interface Protocol<Body, Frame, Event, State> {
   readonly body: ProtocolBody<Body>
   /** Response side: streaming state machine. */
   readonly stream: ProtocolStream<Frame, Event, State>
+  /** Whether `body.from` lowers `Message.effort(...)` markers; wrappers around another `body.from` must forward it. */
+  readonly supportsEffortUpdates?: (request: LLMRequest) => boolean
 }
 
 export interface ProtocolBody<Body> {

packages/ai/src/schema/messages.ts

@@ -9,6 +9,7 @@ import {
   LanguageModelSchema,
   type LanguageModel,
   ProviderOptions,
+  ReasoningEffort,
 } from "./options.js"
 import { ProviderID } from "./ids.js"
 
@@ -217,6 +218,14 @@ export const CompactionPart = Object.assign(compactionPartSchema, {
     Schema.decodeUnknownSync(compactionPartSchema)({ type: "compaction", ...input }),
 })
 
+/** Reasoning effort changed here, from `previous` to `effort`; `undefined` is the model default. */
+export const EffortPart = Schema.Struct({
+  type: Schema.Literal("effort"),
+  effort: Schema.optional(ReasoningEffort),
+  previous: Schema.optional(ReasoningEffort),
+}).annotate({ identifier: "LLM.Content.Effort" })
+export type EffortPart = Schema.Schema.Type<typeof EffortPart>
+
 export const ContentPart = Schema.Union([
   TextPart,
   MediaPart,
@@ -224,6 +233,7 @@ export const ContentPart = Schema.Union([
   ToolResultPart,
   ReasoningPart,
   CompactionPart,
+  EffortPart,
 ]).pipe(Schema.toTaggedUnion("type"))
 export type ContentPart = Schema.Schema.Type<typeof ContentPart>
 
@@ -265,6 +275,9 @@ export namespace Message {
    */
   export const system = (content: SystemContentInput) => make({ role: "system", content })
 
+  export const effort = (input: { readonly effort?: ReasoningEffort; readonly previous?: ReasoningEffort }) =>
+    make({ role: "system", content: [{ type: "effort", effort: input.effort, previous: input.previous }] })
+
   export const tool = (result: ToolResultPart | Parameters<typeof ToolResultPart.make>[0]) =>
     make({ role: "tool", content: ["type" in result ? result : ToolResultPart.make(result)] })
 }

packages/ai/src/schema/options.ts

@@ -140,6 +140,14 @@ export namespace LanguageModelDefaults {
   }
 }
 
+/** Ordered lowest to highest. */
+export const ReasoningEfforts = ["none", "minimal", "low", "medium", "high", "xhigh", "max"] as const
+export type ReasoningEffort = (typeof ReasoningEfforts)[number] | (string & {})
+export const ReasoningEffort = Schema.declare<ReasoningEffort>(
+  (value): value is ReasoningEffort => typeof value === "string",
+  { title: "ReasoningEffort" },
+)
+
 export const LanguageModelToolSchemaCompatibility = Schema.Literals(["gemini", "moonshot"])
 export type LanguageModelToolSchemaCompatibility = Schema.Schema.Type<typeof LanguageModelToolSchemaCompatibility>
 
@@ -165,6 +173,8 @@ export class LanguageModelCompatibility extends Schema.Class<LanguageModelCompat
   requireSignature: Schema.optional(Schema.Boolean),
   /** Supports Anthropic's thinking-prefix mismatch controls. Overrides model-ID detection. */
   supportsThinkingBlockBinding: Schema.optional(Schema.Boolean),
+  /** Supports per-message effort updates. Overrides model-ID detection. */
+  supportsEffortUpdates: Schema.optional(Schema.Boolean),
 }) {}
 
 export namespace LanguageModelCompatibility {

packages/ai/test/effort-updates.test.ts

@@ -0,0 +1,439 @@
+import { describe, expect, test } from "bun:test"
+import { Effect } from "effect"
+import { LLM, LLMRequest, Message, ToolCallPart } from "../src/index.js"
+import { Auth, LLMClient } from "../src/route.js"
+import { compileRequest } from "../src/route/client.js"
+import { AnthropicMessages } from "../src/protocols/anthropic-messages.js"
+import { OpenAIResponses } from "../src/protocols/openai-responses.js"
+import { Gemini } from "../src/protocols/gemini.js"
+import { GoogleVertexMessages, OpenAI } from "../src/providers.js"
+import { applyCachePolicy } from "../src/cache-policy.js"
+import { applyEffortUpdates } from "../src/effort-updates.js"
+import { it, testEffect } from "./lib/effect.js"
+import { dynamicResponse } from "./lib/http.js"
+import { sseEvents } from "./lib/sse.js"
+
+const anthropic = (id: string, compatibility?: { readonly supportsEffortUpdates?: boolean }) =>
+  AnthropicMessages.route
+    .with({ endpoint: { baseURL: "https://api.anthropic.test/v1/" }, auth: Auth.header("x-api-key", "test") })
+    .model({ id, compatibility })
+
+const openai = (id: string, compatibility?: { readonly supportsEffortUpdates?: boolean }) =>
+  OpenAIResponses.route
+    .with({ endpoint: { baseURL: "https://api.openai.test/v1/" }, auth: Auth.bearer("test") })
+    .model({ id, compatibility })
+
+const opus5 = anthropic("claude-opus-5")
+const astra = openai("gpt-6-astra")
+
+const lowFromHigh = Message.effort({ effort: "low", previous: "high" })
+const conversation = [Message.user("Before."), lowFromHigh, Message.user("After.")]
+
+const systemMessages = (body: AnthropicMessages.AnthropicMessagesBody) =>
+  body.messages.filter((message) => message.role === "system")
+
+const updates = (body: OpenAIResponses.OpenAIResponsesBody) =>
+  body.input.filter((item) => "type" in item && item.type === "configuration_update")
+
+describe("applyEffortUpdates", () => {
+  test("keeps the request identity without markers and for protocols that lower them", () => {
+    const plain = LLM.request({ model: opus5, prompt: "hi" })
+    expect(applyEffortUpdates(plain)).toBe(plain)
+
+    const supported = LLM.request({ model: opus5, messages: conversation, providerOptions: { effort: "low" } })
+    expect(applyEffortUpdates(supported)).toBe(supported)
+  })
+
+  it.effect("compiles markers away for protocols without per-message effort", () =>
+    Effect.gen(function* () {
+      const model = Gemini.route
+        .with({
+          endpoint: { baseURL: "https://generativelanguage.test/v1beta/" },
+          auth: Auth.header("x-goog-api-key", "test"),
+        })
+        .model({ id: "gemini-3.5-flash" })
+      const withMarkers = yield* compileRequest(LLM.request({ model, messages: conversation }))
+      const withoutMarkers = yield* compileRequest(
+        LLM.request({ model, messages: [Message.user("Before."), Message.user("After.")] }),
+      )
+
+      expect(withMarkers.body).toEqual(withoutMarkers.body)
+    }),
+  )
+})
+
+describe("cache policy", () => {
+  it.effect("walks the tail breakpoint back past a trailing effort marker", () =>
+    Effect.gen(function* () {
+      const prepared = yield* compileRequest(
+        LLM.request({
+          model: opus5,
+          messages: [Message.user("first"), Message.assistant("reply"), Message.user("latest"), lowFromHigh],
+          providerOptions: { effort: "low" },
+          cache: "auto",
+        }),
+      )
+
+      expect(prepared.body.messages).toEqual([
+        { role: "user", content: [{ type: "text", text: "first" }] },
+        { role: "assistant", content: [{ type: "text", text: "reply" }] },
+        { role: "user", content: [{ type: "text", text: "latest", cache_control: { type: "ephemeral" } }] },
+        { role: "system", content: [], output_config: { effort: "low" } },
+      ])
+    }),
+  )
+})
+
+describe("Anthropic Messages effort updates", () => {
+  it.effect("lowers markers to per-turn system messages and freezes the top-level effort", () =>
+    Effect.gen(function* () {
+      const prepared = yield* compileRequest(
+        LLM.request({ model: opus5, messages: conversation, providerOptions: { effort: "low" }, cache: "none" }),
+      )
+
+      expect(prepared.body.output_config).toEqual({ effort: "high" })
+      expect(prepared.body.messages).toEqual([
+        { role: "user", content: [{ type: "text", text: "Before." }] },
+        { role: "system", content: [], output_config: { effort: "low" } },
+        { role: "user", content: [{ type: "text", text: "After." }] },
+      ])
+    }),
+  )
+
+  it.effect("omits the frozen effort for the model default and sends `high` for a switch back to it", () =>
+    Effect.gen(function* () {
+      const format = { type: "json_schema" as const, schema: { type: "object" } }
+      const prepared = yield* compileRequest(
+        LLM.request({
+          model: opus5,
+          messages: [
+            Message.user("One."),
+            Message.effort({ effort: "low" }),
+            Message.user("Two."),
+            Message.effort({ previous: "low" }),
+            Message.user("Three."),
+          ],
+          providerOptions: { output_config: { format } },
+          cache: "none",
+        }),
+      )
+
+      expect(prepared.body.output_config).toEqual({ format })
+      expect(systemMessages(prepared.body)).toEqual([
+        { role: "system", content: [], output_config: { effort: "low" } },
+        { role: "system", content: [], output_config: { effort: "high" } },
+      ])
+    }),
+  )
+
+  it.effect("requests the mid-conversation output config beta only when markers are sent", () =>
+    Effect.gen(function* () {
+      for (const [model, betas] of [
+        [opus5, "existing-beta,mid-conversation-output-config-2026-07-01"],
+        [anthropic("claude-sonnet-5"), "existing-beta"],
+      ] as const) {
+        const request = LLM.request({
+          model,
+          messages: conversation,
+          providerOptions: { effort: "low" },
+          http: { headers: { "anthropic-beta": "existing-beta" } },
+        })
+        const compiled = yield* compileRequest(request)
+        const prepared = yield* AnthropicMessages.route.prepareTransport(compiled.body, request)
+        expect(prepared.request.headers["anthropic-beta"]).toBe(betas)
+      }
+    }),
+  )
+
+  it.effect("accepts a marker between a tool call and its result", () =>
+    Effect.gen(function* () {
+      const prepared = yield* compileRequest(
+        LLM.request({
+          model: opus5,
+          messages: [
+            Message.user("Weather?"),
+            Message.assistant([ToolCallPart.make({ id: "call_1", name: "lookup", input: {} })]),
+            lowFromHigh,
+            Message.tool({ id: "call_1", name: "lookup", result: { temp: 72 } }),
+          ],
+          providerOptions: { effort: "low" },
+          cache: "none",
+        }),
+      )
+
+      expect(prepared.body.messages).toEqual([
+        { role: "user", content: [{ type: "text", text: "Weather?" }] },
+        { role: "assistant", content: [{ type: "tool_use", id: "call_1", name: "lookup", input: {} }] },
+        { role: "system", content: [], output_config: { effort: "low" } },
+        { role: "user", content: [{ type: "tool_result", tool_use_id: "call_1", content: '{"temp":72}' }] },
+      ])
+    }),
+  )
+
+  it.effect("falls back to a plain top-level effort when history drifted from the current effort", () =>
+    Effect.gen(function* () {
+      const drifted = yield* compileRequest(
+        LLM.request({ model: opus5, messages: conversation, providerOptions: { effort: "medium" }, cache: "none" }),
+      )
+      const plain = yield* compileRequest(
+        LLM.request({
+          model: opus5,
+          messages: [Message.user("Before."), Message.user("After.")],
+          providerOptions: { effort: "medium" },
+          cache: "none",
+        }),
+      )
+
+      expect(drifted.body).toEqual(plain.body)
+      expect(drifted.body.output_config).toEqual({ effort: "medium" })
+    }),
+  )
+
+  for (const [id, supported] of [
+    ["claude-opus-5", true],
+    ["claude-opus-5-20260901", true],
+    ["anthropic/claude-opus-5", true],
+    ["claude-fable-5-1", true],
+    ["claude-mythos-5-1", true],
+    ["claude-fable-5", false],
+    ["claude-opus-4-8", false],
+    ["claude-sonnet-5", false],
+    ["kimi-k2.5", false],
+  ] as const) {
+    it.effect(`${supported ? "lowers" : "strips"} markers for ${id}`, () =>
+      Effect.gen(function* () {
+        const prepared = yield* compileRequest(
+          LLM.request({ model: anthropic(id), messages: conversation, providerOptions: { effort: "low" } }),
+        )
+
+        expect(systemMessages(prepared.body)).toHaveLength(supported ? 1 : 0)
+        expect(prepared.body.output_config).toEqual({ effort: supported ? "high" : "low" })
+      }),
+    )
+  }
+
+  it.effect("honors the compatibility override in both directions", () =>
+    Effect.gen(function* () {
+      const enabled = yield* compileRequest(
+        LLM.request({
+          model: anthropic("claude-sonnet-5", { supportsEffortUpdates: true }),
+          messages: conversation,
+          providerOptions: { effort: "low" },
+        }),
+      )
+      const disabled = yield* compileRequest(
+        LLM.request({
+          model: anthropic("claude-opus-5", { supportsEffortUpdates: false }),
+          messages: conversation,
+          providerOptions: { effort: "low" },
+        }),
+      )
+
+      expect(systemMessages(enabled.body)).toHaveLength(1)
+      expect(systemMessages(disabled.body)).toHaveLength(0)
+    }),
+  )
+
+  it.effect("strips markers on the Vertex Anthropic route, whose protocol wrapper does not forward support", () =>
+    Effect.gen(function* () {
+      const prepared = yield* compileRequest(
+        LLM.request({
+          model: GoogleVertexMessages.configure({ accessToken: "test", location: "global", project: "test" }).model(
+            "claude-opus-5",
+          ),
+          messages: conversation,
+          providerOptions: { effort: "low" },
+        }),
+      )
+
+      expect(systemMessages(prepared.body)).toHaveLength(0)
+      expect(prepared.body.output_config).toEqual({ effort: "low" })
+    }),
+  )
+})
+
+describe("OpenAI Responses effort updates", () => {
+  it.effect("lowers markers to configuration_update items and freezes reasoning.effort", () =>
+    Effect.gen(function* () {
+      const prepared = yield* compileRequest(
+        LLM.request({ model: astra, messages: conversation, providerOptions: { reasoningEffort: "low" } }),
+      )
+
+      expect(prepared.body.reasoning).toEqual({ effort: "high" })
+      expect(prepared.body.input).toEqual([
+        { role: "user", content: [{ type: "input_text", text: "Before." }] },
+        { type: "configuration_update", reasoning: { effort: "low" } },
+        { role: "user", content: [{ type: "input_text", text: "After." }] },
+      ])
+    }),
+  )
+
+  it.effect("coalesces consecutive updates so the newest wins", () =>
+    Effect.gen(function* () {
+      const prepared = yield* compileRequest(
+        LLM.request({
+          model: astra,
+          messages: [
+            Message.user("Before."),
+            Message.effort({ effort: "low", previous: "medium" }),
+            Message.effort({ effort: "xhigh", previous: "low" }),
+            Message.user("After."),
+          ],
+          providerOptions: { reasoningEffort: "xhigh" },
+        }),
+      )
+
+      expect(prepared.body.reasoning).toEqual({ effort: "medium" })
+      expect(prepared.body.input).toEqual([
+        { role: "user", content: [{ type: "input_text", text: "Before." }] },
+        { type: "configuration_update", reasoning: { effort: "xhigh" } },
+        { role: "user", content: [{ type: "input_text", text: "After." }] },
+      ])
+    }),
+  )
+
+  it.effect("omits reasoning.effort for the model default and sends `medium` for a switch back to it", () =>
+    Effect.gen(function* () {
+      const prepared = yield* compileRequest(
+        LLM.request({
+          model: astra,
+          messages: [
+            Message.user("One."),
+            Message.effort({ effort: "low" }),
+            Message.user("Two."),
+            Message.effort({ previous: "low" }),
+            Message.user("Three."),
+          ],
+        }),
+      )
+
+      expect(prepared.body.reasoning).toBeUndefined()
+      expect(updates(prepared.body)).toEqual([
+        { type: "configuration_update", reasoning: { effort: "low" } },
+        { type: "configuration_update", reasoning: { effort: "medium" } },
+      ])
+    }),
+  )
+
+  it.effect("falls back to a plain top-level effort when history drifted from the current effort", () =>
+    Effect.gen(function* () {
+      const drifted = yield* compileRequest(
+        LLM.request({ model: astra, messages: conversation, providerOptions: { reasoningEffort: "xhigh" } }),
+      )
+      const plain = yield* compileRequest(
+        LLM.request({
+          model: astra,
+          messages: [Message.user("Before."), Message.user("After.")],
+          providerOptions: { reasoningEffort: "xhigh" },
+        }),
+      )
+
+      expect(drifted.body).toEqual(plain.body)
+      expect(drifted.body.reasoning).toEqual({ effort: "xhigh" })
+    }),
+  )
+
+  it.effect("strips markers when automatic context management is enabled", () =>
+    Effect.gen(function* () {
+      const prepared = yield* compileRequest(
+        LLM.request({
+          model: astra,
+          messages: conversation,
+          providerOptions: { reasoningEffort: "low", contextManagement: [{ type: "compaction" }] },
+        }),
+      )
+
+      expect(updates(prepared.body)).toEqual([])
+      expect(prepared.body.reasoning).toEqual({ effort: "low" })
+      expect(prepared.body.context_management).toEqual([{ type: "compaction" }])
+    }),
+  )
+
+  for (const [id, supported] of [
+    ["gpt-6-astra", true],
+    ["openai/gpt-6-astra", true],
+    ["gpt-6-astra-2026-09-01", false],
+    ["gpt-5.6-sol", false],
+  ] as const) {
+    it.effect(`${supported ? "lowers" : "strips"} markers for ${id}`, () =>
+      Effect.gen(function* () {
+        const prepared = yield* compileRequest(
+          LLM.request({ model: openai(id), messages: conversation, providerOptions: { reasoningEffort: "low" } }),
+        )
+
+        expect(updates(prepared.body)).toHaveLength(supported ? 1 : 0)
+        expect(prepared.body.reasoning).toEqual({ effort: supported ? "high" : "low" })
+      }),
+    )
+  }
+
+  it.effect("honors the compatibility override in both directions", () =>
+    Effect.gen(function* () {
+      const enabled = yield* compileRequest(
+        LLM.request({
+          model: openai("gpt-5.5", { supportsEffortUpdates: true }),
+          messages: conversation,
+          providerOptions: { reasoningEffort: "low" },
+        }),
+      )
+      const disabled = yield* compileRequest(
+        LLM.request({
+          model: openai("gpt-6-astra", { supportsEffortUpdates: false }),
+          messages: conversation,
+          providerOptions: { reasoningEffort: "low" },
+        }),
+      )
+
+      expect(updates(enabled.body)).toHaveLength(1)
+      expect(updates(disabled.body)).toHaveLength(0)
+    }),
+  )
+
+  const checkpoint = { type: "compaction", id: "cmp_1", encrypted_content: "opaque" }
+  const compactRequest = LLM.request({
+    model: OpenAI.configure({ apiKey: "fixture" }).responses("gpt-6-astra"),
+    messages: conversation,
+    providerOptions: { reasoningEffort: "low" },
+  })
+
+  testEffect(
+    dynamicResponse(({ text, respond }) =>
+      Effect.sync(() => {
+        const body = JSON.parse(text)
+        expect(body.reasoning).toEqual({ effort: "high" })
+        expect(body.input).toEqual([
+          { role: "user", content: [{ type: "input_text", text: "Before." }] },
+          { type: "configuration_update", reasoning: { effort: "low" } },
+          { role: "user", content: [{ type: "input_text", text: "After." }] },
+          { type: "compaction_trigger" },
+        ])
+        return respond(sseEvents({ type: "response.completed", response: { id: "resp_1", output: [checkpoint] } }), {
+          headers: { "content-type": "text/event-stream" },
+        })
+      }),
+    ),
+  ).effect("keeps configuration updates in the checkpoint body", () =>
+    Effect.gen(function* () {
+      const result = yield* LLMClient.compact(compactRequest, { mechanism: "trigger" })
+      expect(result.checkpoint.encrypted).toBe("opaque")
+    }),
+  )
+
+  testEffect(
+    dynamicResponse(({ request, text, respond }) =>
+      Effect.sync(() => {
+        expect(new URL(request.url).pathname).toEndWith("/responses/compact")
+        expect(JSON.parse(text).input).toEqual([
+          { role: "user", content: [{ type: "input_text", text: "Before." }] },
+          { role: "user", content: [{ type: "input_text", text: "After." }] },
+        ])
+        return respond(JSON.stringify({ object: "response.compaction", output: [checkpoint] }))
+      }),
+    ),
+  ).effect("drops markers from the compaction endpoint body", () =>
+    Effect.gen(function* () {
+      const result = yield* LLMClient.compact(compactRequest, { mechanism: "endpoint" })
+      expect(result.replacement.map((message) => message.content[0]?.type)).toEqual(["compaction"])
+    }),
+  )
+})

packages/ai/test/provider-package.test.ts

@@ -188,13 +188,13 @@ describe("provider package entrypoints", () => {
       baseURL: "https://provider.example.test/v1/",
       headers: { "x-application": "opencode" },
       body: { service_tier: "priority" },
-      reasoningEffort: "high" as const,
+      providerOptions: { reasoningEffort: "high" as const },
     }
     const deepinfra = DeepInfra.model("google/gemma-3-27b-it", settings)
 
     expect(deepinfra.route.id).toBe("deepinfra-chat")
     expect(deepinfra.route.endpoint.baseURL).toBe("https://provider.example.test/v1/openai")
-    expect(deepinfra.route.defaults.providerOptions).toEqual({ reasoningEffort: "high" })
+    expect(deepinfra.route.defaults.providerOptions).toEqual(settings.providerOptions)
     expect(deepinfra.route.defaults.headers).toEqual(settings.headers)
     expect(deepinfra.route.defaults.http?.body).toEqual(settings.body)
   })
@@ -210,7 +210,7 @@ describe("provider package entrypoints", () => {
         apiKey: "fixture",
         headers: { "x-application": "opencode" },
         body: { custom: true },
-        reasoningEffort: "high",
+        providerOptions: { reasoningEffort: "high" },
       })
       expect(selected.provider).toBe(provider.id)
       expect(selected.route.endpoint.baseURL).toBe(provider.baseURL({ accountId: "account" }))
@@ -231,11 +231,11 @@ describe("provider package entrypoints", () => {
     }
     const openrouter = OpenRouter.model("anthropic/claude-sonnet-4", {
       ...settings,
-      usage: true,
+      providerOptions: { usage: true },
     })
     const xai = XAI.model("grok-4", {
       ...settings,
-      reasoningEffort: "high",
+      providerOptions: { reasoningEffort: "high" },
     })
 
     for (const selected of [openrouter, xai]) {
@@ -269,8 +269,7 @@ describe("provider package entrypoints", () => {
       provider: "example",
       headers: { "x-application": "opencode" },
       body: { service_tier: "priority" },
-      reasoningEffort: "low",
-      store: true,
+      providerOptions: { reasoningEffort: "low", store: true },
     })
 
     expect(String(selected.provider)).toBe("example")
@@ -296,7 +295,7 @@ describe("provider package entrypoints", () => {
       provider: "example",
       headers: { "x-application": "opencode" },
       body: { metadata: { user_id: "user_1" } },
-      effort: "low",
+      providerOptions: { effort: "low" },
     })
 
     expect(String(selected.provider)).toBe("example")
@@ -316,7 +315,7 @@ describe("provider package entrypoints", () => {
     const Anthropic = await import("@opencode/ai/providers/anthropic")
     const selected = Anthropic.model("claude-sonnet-4-6", {
       apiKey: "fixture",
-      thinking: { type: "adaptive" },
+      providerOptions: { thinking: { type: "adaptive" } },
     })
 
     expect(selected.route.defaults.providerOptions).toEqual({ thinking: { type: "adaptive" } })
@@ -410,7 +409,7 @@ describe("provider package entrypoints", () => {
       baseURL: "https://generativelanguage.test/v1beta",
       headers: { "x-application": "opencode" },
       body: { safetySettings: [] },
-      thinkingConfig: { thinkingBudget: 1_024 },
+      providerOptions: { thinkingConfig: { thinkingBudget: 1_024 } },
     })
 
     expect(selected.route.id).toBe("gemini")

packages/ai/test/provider/anthropic-compaction.test.ts

@@ -69,9 +69,7 @@ for (const model of [
       dynamicResponse(({ request, text, respond }) =>
         Effect.sync(() => {
           const body = JSON.parse(text)
-          expect(request.headers["anthropic-beta"]).toBe(
-            "existing-beta,interleaved-thinking-2025-05-14,compact-2026-01-12",
-          )
+          expect(request.headers["anthropic-beta"]).toBe("existing-beta,compact-2026-01-12")
           if (body.messages.length === 1) {
             expect(body.context_management.edits).toEqual([
               {

packages/ai/test/provider/anthropic-thinking-binding.test.ts

@@ -32,9 +32,7 @@ for (const [id, enabled] of [
         enabled ? { type: "adaptive", block_binding: { prefix_mismatch_behavior: "drop_block" } } : undefined,
       )
       expect(prepared.request.headers["anthropic-beta"]).toBe(
-        enabled
-          ? "existing-beta,interleaved-thinking-2025-05-14,thinking-binding-controls-2026-08-01"
-          : "existing-beta,interleaved-thinking-2025-05-14",
+        enabled ? "existing-beta,thinking-binding-controls-2026-08-01" : "existing-beta",
       )
     }),
   )
@@ -55,9 +53,7 @@ it.effect("preserves explicit thinking settings and combines required beta heade
       const prepared = yield* AnthropicMessages.route.prepareTransport(compiled.body, request)
       expect(compiled.body.thinking).toEqual(thinking)
       expect(prepared.request.headers["anthropic-beta"]).toBe(
-        thinking.type === "disabled"
-          ? "interleaved-thinking-2025-05-14,compact-2026-01-12"
-          : "interleaved-thinking-2025-05-14,compact-2026-01-12,thinking-binding-controls-2026-08-01",
+        thinking.type === "disabled" ? "compact-2026-01-12" : "compact-2026-01-12,thinking-binding-controls-2026-08-01",
       )
     }
   }),

packages/ai/test/provider/groq.test.ts

@@ -34,10 +34,12 @@ it.effect("Groq lowers its own options for custom catalog identities and endpoin
         baseURL: "https://gateway.example/v1",
         headers: { "x-client": "test" },
         body: { custom: "value" },
-        reasoningEffort: "default",
-        parallelToolCalls: true,
-        serviceTier: "flex",
-        user: "test-user",
+        providerOptions: {
+          reasoningEffort: "default",
+          parallelToolCalls: true,
+          serviceTier: "flex",
+          user: "test-user",
+        },
       }),
       { provider: "custom-groq" },
     )

packages/ai/test/provider/meta.test.ts

@@ -87,7 +87,7 @@ it.effect("Meta package selectors preserve overrides and Chat token policy on cu
         baseURL: "https://gateway.example/v1",
         headers: { "x-client": "test" },
         body: { custom: "value" },
-        reasoningEffort: "future-effort",
+        providerOptions: { reasoningEffort: "future-effort" },
       })
       expect(model.route.endpoint.baseURL).toBe("https://gateway.example/v1")
       expect(model.route.defaults.headers).toEqual({ "x-client": "test" })

packages/ai/test/provider/native-providers.test.ts

@@ -99,7 +99,7 @@ describe("native OpenAI-compatible providers", () => {
         const settings = {
           apiKey: "fixture",
           baseURL: "https://gateway.example/v1",
-          reasoningEffort: "high",
+          providerOptions: { reasoningEffort: "high" },
         }
         const selected = provider.configure(settings).model("test-model")
         expect(selected.provider).toBe(provider.id)
@@ -143,7 +143,7 @@ describe("native OpenAI-compatible providers", () => {
           tools: [
             ToolDefinition.make({ name: "lookup", description: "Look up data", inputSchema: { type: "object" } }),
           ],
-          store: true,
+          providerOptions: { store: true },
         }),
       )
 
@@ -168,7 +168,7 @@ describe("native OpenAI-compatible providers", () => {
             ]),
             Message.user("Continue."),
           ],
-          store: true,
+          providerOptions: { store: true },
         }),
       )
 
@@ -206,7 +206,7 @@ describe("native OpenAI-compatible providers", () => {
         baseURL: "https://gateway.example/v1",
         headers: { "x-application": "opencode" },
         body: { service_tier: "priority" },
-        reasoningEffort: "high",
+        providerOptions: { reasoningEffort: "high" },
       })
 
       expect(selected.route.endpoint.baseURL).toBe("https://gateway.example/v1")

packages/app/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@opencode/app",
-  "version": "2.0.0",
+  "version": "1.18.15",
   "description": "",
   "type": "module",
   "exports": {

packages/app/src/runtime/i18n/desktop-native.ts

@@ -285,7 +285,7 @@ export const DESKTOP_NATIVE_ENGLISH = {
   "desktop.updater.dialog.later": "Later",
 
   "desktop.cli.installed.title": "CLI Installed",
-  "desktop.cli.installed.message": "CLI installed to {{path}}\n\nRestart your terminal to use the 'opencode' command.",
+  "desktop.cli.installed.message": "CLI installed to {{path}}\n\nRestart your terminal to use the 'opencode2' command.",
   "desktop.cli.failed.title": "Installation Failed",
   "desktop.cli.failed.message": "Failed to install CLI: {{error}}",
 

packages/cli/Dockerfile

@@ -1,16 +0,0 @@
-FROM alpine AS base
-
-ARG BUN_RUNTIME_TRANSPILER_CACHE_PATH=0
-ENV BUN_RUNTIME_TRANSPILER_CACHE_PATH=${BUN_RUNTIME_TRANSPILER_CACHE_PATH}
-RUN apk add --no-cache libgcc libstdc++ ripgrep
-
-FROM base AS build-amd64
-COPY dist/opencode-linux-x64-baseline-musl/bin/opencode /usr/local/bin/opencode
-
-FROM base AS build-arm64
-COPY dist/opencode-linux-arm64-musl/bin/opencode /usr/local/bin/opencode
-
-ARG TARGETARCH
-FROM build-${TARGETARCH}
-RUN opencode --version
-ENTRYPOINT ["opencode"]

packages/cli/bin/opencode.cjs

@@ -1,135 +0,0 @@
-#!/usr/bin/env node
-
-const childProcess = require("child_process")
-const fs = require("fs")
-const path = require("path")
-const os = require("os")
-
-const forwardedSignals =
-  process.platform === "win32" ? ["SIGINT", "SIGTERM", "SIGHUP"] : ["SIGINT", "SIGTERM", "SIGHUP", "SIGUSR1"]
-
-function run(target) {
-  const child = childProcess.spawn(target, process.argv.slice(2), { stdio: "inherit" })
-  child.on("error", (error) => {
-    console.error(error.message)
-    process.exit(1)
-  })
-  const forwarders = {}
-  for (const signal of forwardedSignals) {
-    forwarders[signal] = () => {
-      try {
-        child.kill(signal)
-      } catch {}
-    }
-    process.on(signal, forwarders[signal])
-  }
-  child.on("exit", (code, signal) => {
-    for (const forwardedSignal of forwardedSignals) process.removeListener(forwardedSignal, forwarders[forwardedSignal])
-    if (signal) return process.kill(process.pid, signal)
-    process.exit(typeof code === "number" ? code : 0)
-  })
-}
-
-const envPath = process.env.OPENCODE_BIN_PATH
-const scriptDir = path.dirname(fs.realpathSync(__filename))
-const command = path.basename(__filename).replace(/\.cjs$/, "")
-const nodeBuild = command === "opencode-node"
-const sourceCommand = nodeBuild ? "opencode2-node" : "opencode"
-const cached = path.join(scriptDir, `.${command}`)
-const platform = { darwin: "darwin", linux: "linux", win32: "windows" }[os.platform()] || os.platform()
-const arch = { x64: "x64", arm64: "arm64", arm: "arm" }[os.arch()] || os.arch()
-const base = `@opencode/cli${nodeBuild ? "-node" : ""}-` + platform + "-" + arch
-const binary = platform === "windows" ? `${sourceCommand}.exe` : sourceCommand
-
-function supportsAvx2() {
-  if (arch !== "x64") return false
-  if (platform === "linux") {
-    try {
-      return /(^|\s)avx2(\s|$)/i.test(fs.readFileSync("/proc/cpuinfo", "utf8"))
-    } catch {
-      return false
-    }
-  }
-  if (platform === "darwin") {
-    try {
-      const result = childProcess.spawnSync("sysctl", ["-n", "hw.optional.avx2_0"], { encoding: "utf8", timeout: 1500 })
-      return result.status === 0 && (result.stdout || "").trim() === "1"
-    } catch {
-      return false
-    }
-  }
-  if (platform === "windows") {
-    const command =
-      '(Add-Type -MemberDefinition "[DllImport(""kernel32.dll"")] public static extern bool IsProcessorFeaturePresent(int ProcessorFeature);" -Name Kernel32 -Namespace Win32 -PassThru)::IsProcessorFeaturePresent(40)'
-    for (const executable of ["powershell.exe", "pwsh.exe", "pwsh", "powershell"]) {
-      try {
-        const result = childProcess.spawnSync(executable, ["-NoProfile", "-NonInteractive", "-Command", command], {
-          encoding: "utf8",
-          timeout: 3000,
-          windowsHide: true,
-        })
-        if (result.status !== 0) continue
-        const output = (result.stdout || "").trim().toLowerCase()
-        if (output === "true" || output === "1") return true
-        if (output === "false" || output === "0") return false
-      } catch {
-        continue
-      }
-    }
-  }
-  return false
-}
-
-const names = (() => {
-  if (nodeBuild) return [base]
-  const baseline = arch === "x64" && !supportsAvx2()
-  if (platform === "linux") {
-    const musl = (() => {
-      try {
-        if (fs.existsSync("/etc/alpine-release")) return true
-        const result = childProcess.spawnSync("ldd", ["--version"], { encoding: "utf8" })
-        return ((result.stdout || "") + (result.stderr || "")).toLowerCase().includes("musl")
-      } catch {
-        return false
-      }
-    })()
-    if (musl)
-      return arch === "x64"
-        ? baseline
-          ? [`${base}-baseline-musl`, `${base}-musl`, `${base}-baseline`, base]
-          : [`${base}-musl`, `${base}-baseline-musl`, base, `${base}-baseline`]
-        : [`${base}-musl`, base]
-    return arch === "x64"
-      ? baseline
-        ? [`${base}-baseline`, base, `${base}-baseline-musl`, `${base}-musl`]
-        : [base, `${base}-baseline`, `${base}-musl`, `${base}-baseline-musl`]
-      : [base, `${base}-musl`]
-  }
-  return arch === "x64" ? (baseline ? [`${base}-baseline`, base] : [base, `${base}-baseline`]) : [base]
-})()
-
-function findBinary(startDir) {
-  let current = startDir
-  for (;;) {
-    const modules = path.join(current, "node_modules")
-    if (fs.existsSync(modules))
-      for (const name of names) {
-        const candidate = path.join(modules, name, "bin", binary)
-        if (fs.existsSync(candidate)) return candidate
-      }
-    const parent = path.dirname(current)
-    if (parent === current) return
-    current = parent
-  }
-}
-
-const resolved = envPath || (fs.existsSync(cached) ? cached : findBinary(scriptDir))
-if (!resolved) {
-  console.error(
-    `It seems that your package manager failed to install the right ${command} CLI package. Try manually installing ` +
-      names.map((name) => `"${name}"`).join(" or ") +
-      " package",
-  )
-  process.exit(1)
-}
-run(resolved)

packages/cli/bin/opencode2.cjs

@@ -1,4 +1,134 @@
 #!/usr/bin/env node
 
-console.log("opencode2 is now just opencode. run opencode")
-process.exit(1)
+const childProcess = require("child_process")
+const fs = require("fs")
+const path = require("path")
+const os = require("os")
+
+const forwardedSignals =
+  process.platform === "win32" ? ["SIGINT", "SIGTERM", "SIGHUP"] : ["SIGINT", "SIGTERM", "SIGHUP", "SIGUSR1"]
+
+function run(target) {
+  const child = childProcess.spawn(target, process.argv.slice(2), { stdio: "inherit" })
+  child.on("error", (error) => {
+    console.error(error.message)
+    process.exit(1)
+  })
+  const forwarders = {}
+  for (const signal of forwardedSignals) {
+    forwarders[signal] = () => {
+      try {
+        child.kill(signal)
+      } catch {}
+    }
+    process.on(signal, forwarders[signal])
+  }
+  child.on("exit", (code, signal) => {
+    for (const forwardedSignal of forwardedSignals) process.removeListener(forwardedSignal, forwarders[forwardedSignal])
+    if (signal) return process.kill(process.pid, signal)
+    process.exit(typeof code === "number" ? code : 0)
+  })
+}
+
+const envPath = process.env.OPENCODE_BIN_PATH
+const scriptDir = path.dirname(fs.realpathSync(__filename))
+const command = path.basename(__filename).replace(/\.cjs$/, "")
+const nodeBuild = command === "opencode2-node"
+const cached = path.join(scriptDir, `.${command}`)
+const platform = { darwin: "darwin", linux: "linux", win32: "windows" }[os.platform()] || os.platform()
+const arch = { x64: "x64", arm64: "arm64", arm: "arm" }[os.arch()] || os.arch()
+const base = `@opencode/cli${nodeBuild ? "-node" : ""}-` + platform + "-" + arch
+const binary = platform === "windows" ? `${command}.exe` : command
+
+function supportsAvx2() {
+  if (arch !== "x64") return false
+  if (platform === "linux") {
+    try {
+      return /(^|\s)avx2(\s|$)/i.test(fs.readFileSync("/proc/cpuinfo", "utf8"))
+    } catch {
+      return false
+    }
+  }
+  if (platform === "darwin") {
+    try {
+      const result = childProcess.spawnSync("sysctl", ["-n", "hw.optional.avx2_0"], { encoding: "utf8", timeout: 1500 })
+      return result.status === 0 && (result.stdout || "").trim() === "1"
+    } catch {
+      return false
+    }
+  }
+  if (platform === "windows") {
+    const command =
+      '(Add-Type -MemberDefinition "[DllImport(""kernel32.dll"")] public static extern bool IsProcessorFeaturePresent(int ProcessorFeature);" -Name Kernel32 -Namespace Win32 -PassThru)::IsProcessorFeaturePresent(40)'
+    for (const executable of ["powershell.exe", "pwsh.exe", "pwsh", "powershell"]) {
+      try {
+        const result = childProcess.spawnSync(executable, ["-NoProfile", "-NonInteractive", "-Command", command], {
+          encoding: "utf8",
+          timeout: 3000,
+          windowsHide: true,
+        })
+        if (result.status !== 0) continue
+        const output = (result.stdout || "").trim().toLowerCase()
+        if (output === "true" || output === "1") return true
+        if (output === "false" || output === "0") return false
+      } catch {
+        continue
+      }
+    }
+  }
+  return false
+}
+
+const names = (() => {
+  if (nodeBuild) return [base]
+  const baseline = arch === "x64" && !supportsAvx2()
+  if (platform === "linux") {
+    const musl = (() => {
+      try {
+        if (fs.existsSync("/etc/alpine-release")) return true
+        const result = childProcess.spawnSync("ldd", ["--version"], { encoding: "utf8" })
+        return ((result.stdout || "") + (result.stderr || "")).toLowerCase().includes("musl")
+      } catch {
+        return false
+      }
+    })()
+    if (musl)
+      return arch === "x64"
+        ? baseline
+          ? [`${base}-baseline-musl`, `${base}-musl`, `${base}-baseline`, base]
+          : [`${base}-musl`, `${base}-baseline-musl`, base, `${base}-baseline`]
+        : [`${base}-musl`, base]
+    return arch === "x64"
+      ? baseline
+        ? [`${base}-baseline`, base, `${base}-baseline-musl`, `${base}-musl`]
+        : [base, `${base}-baseline`, `${base}-musl`, `${base}-baseline-musl`]
+      : [base, `${base}-musl`]
+  }
+  return arch === "x64" ? (baseline ? [`${base}-baseline`, base] : [base, `${base}-baseline`]) : [base]
+})()
+
+function findBinary(startDir) {
+  let current = startDir
+  for (;;) {
+    const modules = path.join(current, "node_modules")
+    if (fs.existsSync(modules))
+      for (const name of names) {
+        const candidate = path.join(modules, name, "bin", binary)
+        if (fs.existsSync(candidate)) return candidate
+      }
+    const parent = path.dirname(current)
+    if (parent === current) return
+    current = parent
+  }
+}
+
+const resolved = envPath || (fs.existsSync(cached) ? cached : findBinary(scriptDir))
+if (!resolved) {
+  console.error(
+    `It seems that your package manager failed to install the right ${command} CLI package. Try manually installing ` +
+      names.map((name) => `"${name}"`).join(" or ") +
+      " package",
+  )
+  process.exit(1)
+}
+run(resolved)

packages/cli/package.json

@@ -1,11 +1,10 @@
 {
   "$schema": "https://json.schemastore.org/package.json",
   "name": "@opencode/cli",
-  "version": "2.0.0",
+  "version": "1.18.4",
   "type": "module",
   "license": "MIT",
   "bin": {
-    "opencode": "./bin/opencode.cjs",
     "opencode2": "./bin/opencode2.cjs"
   },
   "files": [

packages/cli/script/build.ts

@@ -12,7 +12,7 @@ import { verifyArtifact, verifySimulationGraph } from "./verify-artifact"
 import { resolveOpencodePty } from "./opencode-pty"
 
 const dir = path.resolve(import.meta.dirname, "..")
-const binary = "opencode"
+const binary = "opencode2"
 const outdir = path.resolve(
   dir,
   process.argv.find((arg) => arg.startsWith("--outdir="))?.slice("--outdir=".length) ?? "dist",
@@ -149,7 +149,7 @@ export default { path: file, version: ${JSON.stringify(opencodePty.version)}, sh
     },
     define: {
       OPENCODE_VERSION: `'${Script.version}'`,
-      OPENCODE_CLI_NAME: "'opencode'",
+      OPENCODE_CLI_NAME: `'${binary}'`,
       OPENCODE_CHANNEL: `'${Script.channel}'`,
       OPENCODE_ARTIFACT: `'cli'`,
       OPENCODE_LIBC: item.os === "linux" ? `'${item.abi ?? "glibc"}'` : "undefined",

packages/cli/script/postinstall.mjs

@@ -12,11 +12,10 @@ const require = createRequire(import.meta.url)
 const packageJson = JSON.parse(fs.readFileSync(path.join(directory, "package.json"), "utf8"))
 const command = Object.keys(packageJson.bin ?? {})[0]
 if (!command) throw new Error("OpenCode package does not declare a binary")
-const sourceCommand = packageJson.opencodeSourceBinary ?? command
 
 const platform = { darwin: "darwin", linux: "linux", win32: "windows" }[os.platform()] ?? os.platform()
 const arch = { x64: "x64", arm64: "arm64", arm: "arm" }[os.arch()] ?? os.arch()
-const sourceBinary = platform === "windows" ? `${sourceCommand}.exe` : sourceCommand
+const sourceBinary = platform === "windows" ? `${command}.exe` : command
 const targetBinary = path.resolve(directory, packageJson.bin[command])
 const dependencies = packageJson.optionalDependencies ?? {}
 const base = Object.keys(dependencies).find((name) => name.endsWith(`-${platform}-${arch}`))

packages/cli/script/publish-aur.ts

@@ -6,10 +6,15 @@ import path from "node:path"
 import { fileURLToPath } from "node:url"
 import { UpdateArtifact } from "../../../script/update-artifact"
 
-if (Script.channel !== "beta") throw new Error("AUR publishing requires the beta channel")
-const name = "opencode-beta"
-const command = "opencode"
-if (!/^\d+\.\d+\.\d+-beta[.-]\d+(?:\.\d+)?$/.test(Script.version)) throw new Error("Expected a beta release version")
+if (Script.channel !== "beta" && Script.channel !== "latest") {
+  throw new Error("AUR publishing requires the beta or latest channel")
+}
+const beta = Script.channel === "beta"
+const name = beta ? "opencode-beta" : "opencode-bin"
+const command = beta ? "opencode2" : "opencode"
+if (!(beta ? /^\d+\.\d+\.\d+-beta[.-]\d+(?:\.\d+)?$/ : /^\d+\.\d+\.\d+$/).test(Script.version)) {
+  throw new Error(`Expected a ${Script.channel} release version`)
+}
 
 const dir = fileURLToPath(new URL("..", import.meta.url))
 const root = path.resolve(process.env.OPENCODE_CLI_DIST ?? path.join(dir, "dist"))
@@ -17,7 +22,6 @@ const outdir = path.join(root, `aur-${name}`)
 const dryRun = process.argv.includes("--dry-run")
 const pkgver = Script.version.replaceAll("-", ".")
 const license = Bun.file(path.join(dir, "..", "..", "LICENSE"))
-const shim = "#!/bin/sh\necho 'opencode2 is now just opencode. run opencode'\nexit 1\n"
 
 await rm(outdir, { recursive: true, force: true })
 await mkdir(path.dirname(outdir), { recursive: true })
@@ -44,7 +48,6 @@ const sources = await Promise.all(
 )
 
 await Bun.write(path.join(outdir, "LICENSE"), license)
-await Bun.write(path.join(outdir, "opencode2"), shim)
 await Bun.write(
   path.join(outdir, "PKGBUILD"),
   [
@@ -52,22 +55,21 @@ await Bun.write(
     `pkgname=${name}`,
     `pkgver=${pkgver}`,
     "pkgrel=1",
-    "pkgdesc='OpenCode beta - the AI coding agent for the terminal'",
+    `pkgdesc='OpenCode${beta ? " V2 beta" : ""} - the AI coding agent for the terminal'`,
     "url='https://github.com/anomalyco/opencode'",
     "arch=('x86_64' 'aarch64')",
     "license=('MIT')",
     "depends=('glibc' 'gcc-libs' 'ripgrep')",
-    `provides=('${command}' 'opencode2')`,
-    `conflicts=('${command}' 'opencode2')`,
+    `provides=('${command}')`,
+    `conflicts=('${command}')`,
     // Stripping a compiled Bun executable can damage its embedded application.
     "options=('!strip' '!debug')",
-    "source=('LICENSE' 'opencode2')",
-    `sha256sums=('${new Bun.CryptoHasher("sha256").update(await license.arrayBuffer()).digest("hex")}' '${new Bun.CryptoHasher("sha256").update(shim).digest("hex")}')`,
+    "source=('LICENSE')",
+    `sha256sums=('${new Bun.CryptoHasher("sha256").update(await license.arrayBuffer()).digest("hex")}')`,
     ...sources,
     "",
     "package() {",
-    `  install -Dm755 "$srcdir/package/bin/opencode" "$pkgdir/usr/bin/${command}"`,
-    '  install -Dm755 "$srcdir/opencode2" "$pkgdir/usr/bin/opencode2"',
+    `  install -Dm755 "$srcdir/package/bin/opencode2" "$pkgdir/usr/bin/${command}"`,
     '  install -Dm644 "$srcdir/LICENSE" "$pkgdir/usr/share/licenses/$pkgname/LICENSE"',
     "}",
     "",
@@ -77,7 +79,7 @@ await Bun.write(path.join(outdir, ".SRCINFO"), await $`makepkg --printsrcinfo`.c
 console.log(`Prepared ${name} ${pkgver} in ${outdir}`)
 if (dryRun) process.exit(0)
 
-await $`git add PKGBUILD .SRCINFO LICENSE opencode2`.cwd(outdir)
+await $`git add PKGBUILD .SRCINFO LICENSE`.cwd(outdir)
 if ((await $`git diff --cached --quiet`.cwd(outdir).nothrow()).exitCode !== 0) {
   await $`git commit -m ${`chore: update ${name} to ${pkgver}`}`.cwd(outdir)
   await $`git push origin master`.cwd(outdir)

packages/cli/script/publish.ts

@@ -29,8 +29,6 @@ async function publish(dir: string, name: string, version: string) {
 async function publishDistribution(input: {
   root: string
   name: string
-  command: string
-  legacyCommand?: string
   binary: string
   packagePrefix: string
   artifact: string
@@ -50,7 +48,7 @@ async function publishDistribution(input: {
 
   await $`mkdir -p ${input.root}/${input.name}/bin`
   await $`cp ./script/postinstall.mjs ${input.root}/${input.name}/postinstall.mjs`
-  await Bun.file(`${input.root}/${input.name}/bin/${input.command}.exe`).write(
+  await Bun.file(`${input.root}/${input.name}/bin/${input.binary}.exe`).write(
     [
       `echo "Error: ${input.name}'s postinstall script was not run." >&2`,
       'echo "" >&2',
@@ -60,19 +58,11 @@ async function publishDistribution(input: {
       "",
     ].join("\n"),
   )
-  if (input.legacyCommand)
-    await Bun.file(`${input.root}/${input.name}/bin/${input.legacyCommand}.cjs`).write(
-      `#!/usr/bin/env node\n\nconsole.log(${JSON.stringify(`opencode2 is now just opencode. run ${input.command}`)})\nprocess.exit(1)\n`,
-    )
   await Bun.file(`${input.root}/${input.name}/package.json`).write(
     JSON.stringify(
       {
         name: input.name,
-        bin: {
-          [input.command]: `./bin/${input.command}.exe`,
-          ...(input.legacyCommand ? { [input.legacyCommand]: `./bin/${input.legacyCommand}.cjs` } : {}),
-        },
-        ...(input.command !== input.binary ? { opencodeSourceBinary: input.binary } : {}),
+        bin: { [input.binary]: `./bin/${input.binary}.exe` },
         scripts: { postinstall: "node ./postinstall.mjs" },
         version,
         license: pkg.license,
@@ -130,9 +120,7 @@ async function publishDistribution(input: {
 await publishDistribution({
   root,
   name: pkg.name,
-  command: "opencode",
-  legacyCommand: "opencode2",
-  binary: "opencode",
+  binary: "opencode2",
   packagePrefix: "@opencode/cli-",
   artifact: "cli",
 })
@@ -140,18 +128,13 @@ if (existsSync(path.join(root, "node"))) {
   await publishDistribution({
     root: path.join(root, "node"),
     name: "@opencode/cli-node",
-    command: "opencode2-node",
     binary: "opencode2-node",
     packagePrefix: "@opencode/cli-node-",
     artifact: "cli-node",
   })
 }
 
-if (Script.channel === "latest" && Script.release && !dryRun) {
-  await $`docker buildx build --platform linux/amd64,linux/arm64 --tag ghcr.io/anomalyco/opencode:${Script.version} --push .`
-}
-
-if (Script.channel === "beta" && Script.release) {
+if ((Script.channel === "beta" || Script.channel === "latest") && Script.release) {
   await $`bun ./script/publish-aur.ts ${dryRun ? ["--dry-run"] : []}`.env({ ...process.env, OPENCODE_CLI_DIST: root })
 }
 

packages/cli/script/service-smoke.ts

@@ -11,10 +11,7 @@ import path from "node:path"
 const nodeBuild = process.argv.includes("--node")
 const target = `cli${nodeBuild ? "-node" : ""}-${process.platform === "win32" ? "windows" : process.platform}-${process.arch}`
 const directory = path.join(import.meta.dir, "..", "dist", ...(nodeBuild ? ["node"] : []), target, "bin")
-const binary = path.join(
-  directory,
-  `${nodeBuild ? "opencode2-node" : "opencode"}${process.platform === "win32" ? ".exe" : ""}`,
-)
+const binary = path.join(directory, `opencode2${nodeBuild ? "-node" : ""}${process.platform === "win32" ? ".exe" : ""}`)
 if (!(await Bun.file(binary).exists())) throw new Error(`Missing compiled CLI in ${directory}`)
 
 const root = await fs.realpath(await fs.mkdtemp(path.join(os.tmpdir(), "opencode-service-smoke-")))

packages/cli/src/commands/commands.ts

@@ -36,7 +36,7 @@ const PermissionParams = {
 }
 
 const Root = Spec.make(typeof OPENCODE_CLI_NAME === "string" ? OPENCODE_CLI_NAME : "opencode", {
-  description: "OpenCode command line interface",
+  description: "OpenCode 2.0 preview command line interface",
   params: {
     ...ServerParams,
     ...PermissionParams,

packages/cli/src/services/updater.ts

@@ -105,7 +105,7 @@ const make = Effect.gen(function* () {
       global.home,
       ".opencode",
       "bin",
-      process.platform === "win32" ? "opencode.exe" : "opencode",
+      process.platform === "win32" ? "opencode2.exe" : "opencode2",
     )
     if (path.resolve(process.execPath) === path.resolve(binary)) return "curl"
     if (!installedPackage) return
@@ -186,10 +186,7 @@ const make = Effect.gen(function* () {
         "npm",
         "install",
         "--global",
-        ...((OPENCODE_ARTIFACT === "cli" && !installedPackage?.endsWith("/cli-node")) ||
-        (installedPackage && packageName !== installedPackage)
-          ? ["--force"]
-          : []),
+        ...(installedPackage && packageName !== installedPackage ? ["--force"] : []),
         target,
       ],
       pnpm: ["pnpm", "add", "--global", `--allow-build=${packageName}`, target],

packages/cli/test/config.test.ts

@@ -423,24 +423,24 @@ test("updates effective duplicate canonical keybinds", async () => {
   const file = path.join(directory.path, "cli.json")
   await Bun.write(
     file,
-    `{"keybinds":{"session.delete":"first","session.delete":"last","opencode.settings":"off","opencode.settings":"on"}}`,
+    `{"keybinds":{"session.delete":"first","session.delete":"last","permission.mode":"off","permission.mode":"on"}}`,
   )
 
   const config = await run(
     directory.path,
     Effect.gen(function* () {
       const service = yield* Config.Service
-      expect((yield* service.get()).keybinds).toEqual({ "session.delete": "last", "opencode.settings": "on" })
+      expect((yield* service.get()).keybinds).toEqual({ "session.delete": "last", "permission.mode": "on" })
       return yield* service.update((draft) => {
-        draft.keybinds = { ...draft.keybinds, "session.delete": "changed", "opencode.settings": "changed" }
+        draft.keybinds = { ...draft.keybinds, "session.delete": "changed", "permission.mode": "changed" }
       })
     }),
   )
 
-  expect(config.keybinds).toEqual({ "session.delete": "changed", "opencode.settings": "changed" })
+  expect(config.keybinds).toEqual({ "session.delete": "changed", "permission.mode": "changed" })
   expect(parse(await Bun.file(file).text()).keybinds).toEqual({
     "session.delete": "changed",
-    "opencode.settings": "changed",
+    "permission.mode": "changed",
   })
 })
 

packages/cli/test/updater-install.test.ts

@@ -100,7 +100,7 @@ function fixture(
 }
 
 const installs = [
-  { method: "npm", command: ["npm", "install", "--global", "--force", "@opencode/cli@2.3.4-beta.1"] },
+  { method: "npm", command: ["npm", "install", "--global", "@opencode/cli@2.3.4-beta.1"] },
   {
     method: "pnpm",
     command: ["pnpm", "add", "--global", "--allow-build=@opencode/cli", "@opencode/cli@2.3.4-beta.1"],

packages/client/package.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://json.schemastore.org/package.json",
   "name": "@opencode/client",
-  "version": "2.0.0",
+  "version": "1.17.13",
   "type": "module",
   "license": "MIT",
   "repository": {

packages/codemode/interpreter-support.md

@@ -9,8 +9,7 @@ standard-library surface that programs can use today, plus concrete gaps that ma
 - Intentional boundaries are not listed as compatibility work.
 
 When behavior changes, update this file and the tests in the same change. The implementation and tests remain the
-ultimate source of truth. Upstream test262 files run verbatim from `test/test262`; a failing file is listed in
-`test/test262/skipped.txt` and its gap is an unchecked item here (see `test/test262/README.md`).
+ultimate source of truth.
 
 ## Source and execution model
 
@@ -26,10 +25,6 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] The global `search(...)` built-in: synchronous tool discovery that counts as an admitted tool call and is
       shadowable by program declarations like other globals.
 - [x] Cooperative timeout, an optional total tool-call limit, output bounding, and unrestricted tool-call concurrency.
-- [ ] 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"`.
-- [ ] Valid JavaScript rejected by TypeScript transpilation before interpretation, such as `in` inside a destructuring
-      default in a `for...of` head and Unicode-escaped keywords.
 
 ## Values and literals
 
@@ -69,11 +64,6 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] Array binding and assignment destructuring from strings, Maps, Sets, URLSearchParams, custom synchronous
       iterators, and synchronous generators, including stepwise elisions/rest and `IteratorClose` on early completion
       or binding/default failure.
-- [ ] Object destructuring from primitives follows ToObject (`const { length } = "abc"`, `const {} = 1`); non-object
-      sources are rejected.
-- [ ] Destructuring a key that member access resolves through the owning built-in, such as
-      `const { constructor } = error`, reads `undefined`.
-- [ ] Member expressions as `for...in` targets (`for (x.y in obj)`).
 
 ## Statements and control flow
 
@@ -121,15 +111,6 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [ ] User-defined constructor calls.
 - [ ] `Function.prototype.call`, `apply`, and `bind` for CodeMode functions.
 - [ ] Classes and private fields.
-- [x] Functions are objects: they hold own properties (`fn.count = 1`), enumerate them, and expose read-only `name`
-      and `length`. Names follow JavaScript's NamedEvaluation: declarations, named expressions, bindings,
-      assignments, object literal keys, and destructuring or parameter defaults.
-- [ ] `name` and `length` of built-in functions such as `Math.max` or `"a".includes`.
-- [ ] 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.
-- [ ] 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] 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
@@ -173,8 +154,6 @@ 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.
-- [ ] Operators, `switch` discriminants, and coercion helpers such as `String` and `isNaN` applied to functions and
-      namespaces; JavaScript coerces them, the interpreter rejects non-data operands.
 
 ## Promises and tools
 
@@ -246,8 +225,7 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] Circular references are rejected when created (`o.self = o`, `array.push(array)`), not at serialization as in JS.
 - [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.
-- [ ] `Object.prototype` methods on values: `toString`, `toLocaleString`, `valueOf`, and `hasOwnProperty`.
+      and null-prototype results.
 
 ## Arrays
 
@@ -267,18 +245,10 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [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`.
-- [x] Canonical array/string index parsing: keys such as `"01"` are ordinary properties rather than aliases of index
-      `1`.
+- [x] Canonical array/string index parsing: keys such as `"01"` remain non-index properties rather than aliasing index
+      `1`; arbitrary array-property assignment remains unsupported.
 - [x] `Array.prototype.sort` preserves trailing holes, while `toSorted` densifies holes into `undefined` elements,
       like JavaScript.
-- [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`.
-- [ ] Iterator objects from `keys`, `values`, and `entries` with a live `next()`.
 
 ## Strings
 
@@ -362,7 +332,7 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [x] `test`, `exec`, and `toString`.
 - [x] Readable `source`, `flags`, `lastIndex`, `hasIndices`, `global`, `ignoreCase`, `multiline`, `sticky`, `unicode`,
       `unicodeSets`, and `dotAll`.
-- [x] Captures, named groups, match `.index` and `.input`, and stateful global matching.
+- [x] Captures, named groups, match `.index`, and stateful global matching.
 - [x] Integration with supported String methods, including function replacers.
 - [x] Writable `lastIndex`.
 - [x] Match `indices` metadata for the `d` flag, including named groups on `exec`, `match`, and `matchAll` results.
@@ -421,5 +391,3 @@ ultimate source of truth. Upstream test262 files run verbatim from `test/test262
 - [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.
-- [ ] Failures raised by the interpreter itself carry the generic `Error` name where JavaScript throws a `TypeError`,
-      `RangeError`, or `ReferenceError`, so `e instanceof TypeError` and `e.constructor === TypeError` are false.

packages/codemode/package.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://json.schemastore.org/package.json",
   "name": "@opencode/codemode",
-  "version": "2.0.0",
+  "version": "1.18.4",
   "description": "Effect-native confined code execution over schema-described tools",
   "type": "module",
   "license": "MIT",

packages/codemode/script/sync-test262.ts

@@ -1,62 +0,0 @@
-// Copies the manifest's test262 directories from a local checkout into test/test262, verbatim.
-// Files needing unsupported flags, features, or harness includes, or whose code crosses one of the
-// interpreter's intentional boundaries, are not copied, so the vendored tree is exactly what
-// test/test262.test.ts runs.
-//
-// Usage: bun run script/sync-test262.ts /path/to/test262
-import path from "node:path"
-import { rm } from "node:fs/promises"
-
-type Frontmatter = { flags?: Array<string>; features?: Array<string>; includes?: Array<string> }
-
-const root = path.resolve(import.meta.dir, "../test/test262")
-const manifest = (await Bun.file(path.join(root, "manifest.json")).json()) as {
-  revision: string
-  directories: Array<string>
-  harness: Array<string>
-  flags: Array<string>
-  features: Array<string>
-  boundaries: Record<string, string>
-}
-const boundaries = Object.entries(manifest.boundaries).map(([name, pattern]) => [name, new RegExp(pattern)] as const)
-const checkout = process.argv[2]
-if (checkout === undefined) {
-  console.error("usage: bun run script/sync-test262.ts /path/to/test262")
-  process.exit(1)
-}
-const head = (await Bun.$`git -C ${checkout} rev-parse HEAD`.text()).trim()
-if (head !== manifest.revision) {
-  console.error(`checkout is at ${head}; manifest pins ${manifest.revision}`)
-  process.exit(1)
-}
-
-const excluded = new Map<string, number>()
-let copied = 0
-for (const dir of manifest.directories) {
-  await rm(path.join(root, dir), { recursive: true, force: true })
-  const from = path.join(checkout, "test", dir)
-  for await (const file of new Bun.Glob("**/*.js").scan({ cwd: from })) {
-    if (file.endsWith("_FIXTURE.js")) continue
-    const source = await Bun.file(path.join(from, file)).text()
-    const start = source.indexOf("/*---")
-    const end = source.indexOf("---*/", start)
-    const meta = start === -1 ? {} : (Bun.YAML.parse(source.slice(start + 5, end)) as Frontmatter)
-    const code = start === -1 ? source : source.slice(end + 5)
-    const reason =
-      meta.flags?.find((flag) => manifest.flags.includes(flag)) ??
-      meta.features?.find((feature) => manifest.features.includes(feature)) ??
-      meta.includes?.find((include) => !manifest.harness.includes(include)) ??
-      boundaries.find(([, pattern]) => pattern.test(code))?.[0]
-    if (reason !== undefined) {
-      excluded.set(reason, (excluded.get(reason) ?? 0) + 1)
-      continue
-    }
-    await Bun.write(path.join(root, dir, file), Bun.file(path.join(from, file)))
-    copied++
-  }
-}
-
-console.log(`copied ${copied} files`)
-for (const [reason, count] of [...excluded].sort((a, b) => b[1] - a[1])) {
-  console.log(`  excluded ${String(count).padStart(5)}  ${reason}`)
-}

packages/codemode/script/test262-report.ts

@@ -1,55 +0,0 @@
-// Runs every vendored test262 file, including skipped ones, and groups failures by cause. Pass
-// --write to regenerate test/test262/skipped.txt from the current failures.
-//
-// Usage: bun run script/test262-report.ts [--write] [path-prefix]
-import path from "node:path"
-import { root, run, skipped } from "../test/test262/run.js"
-
-const write = process.argv.includes("--write")
-const prefix = process.argv.slice(2).find((arg) => !arg.startsWith("--")) ?? ""
-const files = [...new Bun.Glob("**/*.js").scanSync({ cwd: root })].filter((file) => file.startsWith(prefix)).sort()
-
-const failures: Array<{ file: string; reason: string }> = []
-const recovered: Array<string> = []
-for (const file of files) {
-  const outcome = await run(file)
-  if (outcome.status === "fail") failures.push({ file, reason: outcome.reason })
-  if (outcome.status === "pass" && skipped.has(file)) recovered.push(file)
-}
-
-// Collapse a reason to the part that identifies the cause rather than the test.
-const bucket = (reason: string) => {
-  const syntax = reason.match(/Syntax '([A-Za-z]+)' is not supported/)
-  if (syntax) return `unsupported syntax ${syntax[1]}`
-  if (reason.startsWith("expected ")) return reason.replace(/ but got .*/, " but the program ran")
-  return reason
-    .replace(/^(\$DONE: |ExecutionFailure: |InvalidDataValue: |ParseError: |Uncaught: |Test262Error: |Error: )+/, "")
-    .replace(/ \(line \d+, col \d+\)/, "")
-    .replace(/^[\w$]+\.(\w+) is not a function/, ".$1 is not a function")
-    .replace(/^[\w$]+ cannot be constructed/, "… cannot be constructed")
-    .replace(/'[^']*'/g, "'…'")
-    .slice(0, 100)
-}
-
-const buckets = new Map<string, Array<string>>()
-for (const failure of failures) {
-  const key = bucket(failure.reason)
-  buckets.set(key, [...(buckets.get(key) ?? []), failure.file])
-}
-
-console.log(`${files.length - failures.length} pass, ${failures.length} fail of ${files.length}\n`)
-for (const [key, list] of [...buckets].sort((a, b) => b[1].length - a[1].length)) {
-  console.log(`${String(list.length).padStart(5)}  ${key}`)
-  for (const file of list.slice(0, 3)) console.log(`         ${file}`)
-  if (list.length > 3) console.log(`         … ${list.length - 3} more`)
-}
-if (recovered.length > 0) {
-  console.log(`\n${recovered.length} skipped files pass now; remove them from skipped.txt:`)
-  for (const file of recovered) console.log(`         ${file}`)
-}
-
-if (write) {
-  const lines = failures.map((failure) => `${failure.file}  # ${bucket(failure.reason)}`)
-  await Bun.write(path.join(root, "skipped.txt"), `${lines.join("\n")}\n`)
-  console.log(`\nwrote ${lines.length} entries to skipped.txt`)
-}

packages/codemode/src/data.ts

@@ -1,16 +1,11 @@
 export * as Data from "./data.js"
 
 import type { DiagnosticKind } from "./codemode.js"
-import {
-  ownEntries,
-  parseArrayIndex,
-  ProgramArray,
-  ProgramFunction,
-  ProgramObject,
-  set,
-} from "./interpreter/objects.js"
 import { Values } from "./values.js"
 
+/** A null-prototype object owned by the program. */
+export type SafeObject = Record<string, unknown>
+
 const MAX_VALUE_DEPTH = 32
 
 export class ToolRuntimeError extends Error {
@@ -28,15 +23,15 @@ export class ToolRuntimeError extends Error {
 }
 
 /**
- * Brings a host-produced value into the program: program and runtime values pass through, their
- * host counterparts (Date, RegExp, Map, Set, URL, URLSearchParams) are wrapped, and host objects
- * and arrays are copied.
+ * Brings a host-produced runtime value into the program: runtime values pass through, their host
+ * counterparts (Date, RegExp, Map, Set, URL, URLSearchParams) are wrapped, and objects become
+ * null-prototype copies. Arrays keep extra enumerable properties such as `index` and `groups`.
  */
 export const toProgram = (value: unknown, label: string): unknown => copy(value, label, "program", 0, new Set())
 
 /**
  * Brings host data into the program: Date and URL become strings, other host collections become
- * empty objects, and objects become program copies. Used for tool results and parsed JSON.
+ * empty objects, and objects become null-prototype copies. Used for tool results and parsed JSON.
  */
 export const fromData = (value: unknown, label: string): unknown => copy(value, label, "data", 0, new Set())
 
@@ -49,7 +44,8 @@ export const fromData = (value: unknown, label: string): unknown => copy(value,
 export const toData = (value: unknown, label: string, undefinedAs: "json" | "result" = "json"): unknown =>
   copy(value, label, undefinedAs, 0, new Set())
 
-// "program" and "data" build program objects; "json" and "result" build ordinary objects for the host.
+// "program" and "data" build program-owned null-prototype objects; "json" and "result" build
+// ordinary objects for the host.
 type Mode = "program" | "data" | "json" | "result"
 
 const copy = (value: unknown, label: string, mode: Mode, depth: number, seen: Set<object>): unknown => {
@@ -68,13 +64,9 @@ const copy = (value: unknown, label: string, mode: Mode, depth: number, seen: Se
       `${label} contains an un-awaited Promise; await tool calls (e.g. \`const result = await tools.ns.tool(...)\`) before using their results.`,
     )
   }
-  if (value instanceof ProgramFunction && mode !== "program") {
-    throw new ToolRuntimeError("InvalidDataValue", `${label} must contain data only.`)
-  }
 
-  const plain = mode === "program" || mode === "data"
   if (mode === "program") {
-    if (value instanceof ProgramObject || Values.isValue(value)) return value
+    if (Values.isValue(value)) return value
     if (value instanceof Date) return new Values.Date(value.getTime())
     if (value instanceof RegExp) return new Values.RegExp(value.source, value.flags)
     if (value instanceof Map) {
@@ -93,6 +85,7 @@ const copy = (value: unknown, label: string, mode: Mode, depth: number, seen: Se
     if (value instanceof URLSearchParams) return new Values.URLSearchParams(new URLSearchParams(value))
   }
 
+  const plain = mode === "program" || mode === "data"
   if (value instanceof Values.Date) return Number.isFinite(value.time) ? new Date(value.time).toISOString() : null
   if (value instanceof Date) return Number.isFinite(value.getTime()) ? value.toISOString() : null
   if (value instanceof Values.URL) return value.url.href
@@ -105,7 +98,7 @@ const copy = (value: unknown, label: string, mode: Mode, depth: number, seen: Se
     value instanceof Set ||
     value instanceof URLSearchParams
   ) {
-    return plain ? new ProgramObject() : {}
+    return plain ? (Object.create(null) as SafeObject) : {}
   }
 
   if (seen.has(value)) {
@@ -113,32 +106,17 @@ const copy = (value: unknown, label: string, mode: Mode, depth: number, seen: Se
   }
   seen.add(value)
 
-  if (value instanceof ProgramArray) {
-    const copied = Array.from(value.items, (item) => copy(item, label, mode, depth + 1, seen) ?? null)
-    seen.delete(value)
-    return copied
-  }
-  if (value instanceof ProgramObject) {
-    const copied: Record<string, unknown> = {}
-    for (const [key, item] of ownEntries(value)) {
-      const next = copy(item, label, mode, depth + 1, seen)
-      if (next === undefined && mode === "json") continue
-      define(copied, key, next)
-    }
-    seen.delete(value)
-    return copied
-  }
-
   if (Array.isArray(value)) {
-    if (plain) {
-      const copied = new ProgramArray(value.map((item) => copy(item, label, mode, depth + 1, seen)))
+    // Host output densifies holes to null like JSON; program copies keep them.
+    const copied = plain
+      ? value.map((item) => copy(item, label, mode, depth + 1, seen))
+      : Array.from(value, (item) => copy(item, label, mode, depth + 1, seen) ?? null)
+    if (mode === "program") {
       for (const [key, item] of Object.entries(value)) {
-        if (parseArrayIndex(key) === undefined) set(copied, key, copy(item, label, mode, depth + 1, seen))
+        if (Object.hasOwn(copied, key)) continue
+        define(copied, key, copy(item, label, mode, depth + 1, seen))
       }
-      seen.delete(value)
-      return copied
     }
-    const copied = Array.from(value, (item) => copy(item, label, mode, depth + 1, seen) ?? null)
     seen.delete(value)
     return copied
   }
@@ -148,13 +126,7 @@ const copy = (value: unknown, label: string, mode: Mode, depth: number, seen: Se
     throw new ToolRuntimeError("InvalidDataValue", `${label} must contain plain objects only.`)
   }
 
-  if (plain) {
-    const copied = new ProgramObject()
-    for (const [key, item] of Object.entries(value)) set(copied, key, copy(item, label, mode, depth + 1, seen))
-    seen.delete(value)
-    return copied
-  }
-  const copied: Record<string, unknown> = {}
+  const copied: SafeObject = plain ? (Object.create(null) as SafeObject) : {}
   for (const [key, item] of Object.entries(value)) {
     const next = copy(item, label, mode, depth + 1, seen)
     if (next === undefined && mode === "json") continue
@@ -164,8 +136,8 @@ const copy = (value: unknown, label: string, mode: Mode, depth: number, seen: Se
   return copied
 }
 
-// Own data property regardless of the target's prototype, so a "__proto__" key on a host object
-// never reaches the Object.prototype setter.
+// Own data property regardless of the target's prototype, so a "__proto__" key on a host object or
+// array never reaches the Object.prototype setter.
 const define = (target: object, key: string, value: unknown): void => {
   Object.defineProperty(target, key, { value, enumerable: true, writable: true, configurable: true })
 }

packages/codemode/src/interpreter/errors.ts

@@ -1,11 +1,10 @@
 import { Effect } from "effect"
 import type { Diagnostic } from "../codemode.js"
 import { ToolError } from "../tool-error.js"
-import { toData, ToolRuntimeError } from "../data.js"
+import { type SafeObject, toData, ToolRuntimeError } from "../data.js"
 import { type AstNode, formatLocation, InterpreterRuntimeError, ProgramThrow, sourceLocation } from "./model.js"
 import { containsRuntimeReference } from "./references.js"
 import { type HostCall, HostFunction } from "./host.js"
-import { get, ProgramError, ProgramObject } from "./objects.js"
 import { type Runner } from "./runner.js"
 import {
   coerceToString,
@@ -45,8 +44,12 @@ export const normalizeError = (error: unknown): Diagnostic => {
       message = "a non-data value"
     } else if (typeof value === "string") {
       message = value
-    } else if (value instanceof ProgramObject && typeof get(value, "message") === "string") {
-      message = get(value, "message") as string
+    } else if (
+      value !== null &&
+      typeof value === "object" &&
+      typeof (value as { message?: unknown }).message === "string"
+    ) {
+      message = (value as { message: string }).message
     } else {
       try {
         message = JSON.stringify(toData(value, "Thrown value")) ?? String(value)
@@ -84,14 +87,14 @@ export const caughtErrorValue = (thrown: unknown): unknown => {
   return createErrorValue(name, normalizeError(thrown).message)
 }
 
-const constructErrorValue = (name: string, args: Array<unknown>): ProgramError =>
+const constructErrorValue = (name: string, args: Array<unknown>): SafeObject =>
   createErrorValue(name, args[0] === undefined ? "" : coerceToString(args[0]))
 
 const constructAggregateErrorValue = <R>(
   runner: Runner<R>,
   args: Array<unknown>,
   node: AstNode,
-): Effect.Effect<ProgramError, unknown, R> =>
+): Effect.Effect<SafeObject, unknown, R> =>
   Effect.gen(function* () {
     const cursor = yield* runner.syncIterator(args[0], node)
     if (cursor === undefined) {

packages/codemode/src/interpreter/execute.ts

@@ -7,7 +7,6 @@ import type { DataValue, Diagnostic, ResolvedExecutionLimits, Result } from "../
 import { toData } from "../data.js"
 import { ToolRuntime } from "../tool-runtime.js"
 import { normalizeError } from "./errors.js"
-import type { Host } from "./globals.js"
 import { InterpreterRuntimeError } from "./model.js"
 import { PromiseRuntime } from "./promises.js"
 import { Runtime } from "./runtime.js"
@@ -17,7 +16,6 @@ export const executeProgram = <R>(
   prepared: ToolRuntime.Prepared<R>,
   limits: ResolvedExecutionLimits,
   hooks: ToolRuntime.ToolCallHooks<R>,
-  extraGlobals?: (host: Host<R>) => ReadonlyArray<readonly [string, unknown]>,
 ): Effect.Effect<Result, never, R> => {
   if (code.trim().length === 0) {
     return Effect.succeed({
@@ -41,14 +39,7 @@ export const executeProgram = <R>(
         Effect.gen(function* () {
           const program = parseProgram(code)
           const promises = new PromiseRuntime<R>(scope)
-          const value = yield* new Runtime<R>(
-            tools.execute,
-            tools.search,
-            tools.keys,
-            promises,
-            logs,
-            extraGlobals,
-          ).run(program)
+          const value = yield* new Runtime<R>(tools.execute, tools.search, tools.keys, promises, logs).run(program)
           const result = toData(value, "Execution result", "result") as DataValue
           returned = { value: result, promises }
           const warnings = yield* promises.interrupt()

packages/codemode/src/interpreter/methods.ts

@@ -1,14 +1,13 @@
 import { Effect } from "effect"
-import { toProgram } from "../data.js"
+import { type SafeObject, toProgram } from "../data.js"
 import { dateSetterArgumentCount, invokeDateMethod } from "../stdlib/date.js"
 import { invokeNumberMethod } from "../stdlib/number.js"
 import { invokeRegExpMethod, matchToValue, toHostRegex } from "../stdlib/regexp.js"
 import { invokeURLMethod, uriArgument } from "../stdlib/url.js"
-import { coerceToNumber, coerceToString } from "../stdlib/value.js"
+import { coerceToNumber, coerceToString, errorBrandName } from "../stdlib/value.js"
 import { compareText } from "../tool-runtime.js"
 import { Values } from "../values.js"
 import { type AstNode, IntrinsicReference, InterpreterRuntimeError } from "./model.js"
-import { get, ProgramArray, ProgramObject, record } from "./objects.js"
 import { containsOpaqueReference, rejectCircularInsertion, typeofValue } from "./references.js"
 import { applyCollectionCallback, isSupportedCallback, type Runner, toPrimitive } from "./runner.js"
 
@@ -17,14 +16,6 @@ export const invokeIntrinsic = <R>(
   ref: IntrinsicReference,
   args: Array<unknown>,
   node: AstNode,
-): Effect.Effect<unknown, unknown, R> =>
-  Effect.map(invoke(runner, ref, args, node), (result) => (Array.isArray(result) ? new ProgramArray(result) : result))
-
-const invoke = <R>(
-  runner: Runner<R>,
-  ref: IntrinsicReference,
-  args: Array<unknown>,
-  node: AstNode,
 ): Effect.Effect<unknown, unknown, R> => {
   if (typeof ref.receiver === "string") {
     if (ref.name === "replace" || ref.name === "replaceAll") {
@@ -41,7 +32,7 @@ const invoke = <R>(
   if (typeof ref.receiver === "number") {
     return Effect.succeed(invokeNumberMethod(ref.receiver, ref.name, args, node))
   }
-  if (ref.receiver instanceof ProgramArray) {
+  if (Array.isArray(ref.receiver)) {
     return invokeArrayMethod(runner, ref.receiver, ref.name, args, node)
   }
   if (ref.receiver instanceof Values.Date) {
@@ -224,7 +215,7 @@ const invokeStringMethod = (value: string, name: string, args: Array<unknown>, n
           node,
         )
       }
-      return new ProgramArray(Array.from(value.matchAll(pattern), matchToValue))
+      return Array.from(value.matchAll(pattern), matchToValue)
     }
     case "search": {
       result = value.search(toHostRegex(args[0], name, node))
@@ -297,7 +288,13 @@ const invokeStringReplacer = <R>(
     if (typeof match !== "string" || typeof offset !== "number") {
       throw new InterpreterRuntimeError(`String.${name} produced an invalid replacement match.`, node)
     }
-    if (hasGroups) callbackArgs[callbackArgs.length - 1] = record(groups as Record<string, unknown>)
+    if (hasGroups) {
+      const safeGroups: SafeObject = Object.create(null) as SafeObject
+      for (const [key, group] of Object.entries(groups)) {
+        safeGroups[key] = group
+      }
+      callbackArgs[callbackArgs.length - 1] = safeGroups
+    }
     matches.push({ match, offset, args: callbackArgs })
     return match
   }
@@ -323,11 +320,14 @@ const invokeStringReplacer = <R>(
     let end = 0
     for (const match of matches) {
       const replacement = yield* apply(match.args)
+      // Error values are branded plain objects; toProgram would strip the brand before coercion.
       output.push(
         value.slice(end, match.offset),
         replacement instanceof Values.Promise
           ? "[object Promise]"
-          : coerceToString(toProgram(replacement, `String.${name} replacer result`)),
+          : errorBrandName(replacement)
+            ? coerceToString(replacement)
+            : coerceToString(toProgram(replacement, `String.${name} replacer result`)),
       )
       end = match.offset + match.match.length
     }
@@ -365,7 +365,7 @@ const invokeMapMethod = <R>(
     case "values":
       return Effect.sync(() => Array.from(target.map.values()))
     case "entries":
-      return Effect.sync(() => Array.from(target.map.entries(), ([key, item]) => new ProgramArray([key, item])))
+      return Effect.sync(() => Array.from(target.map.entries(), ([key, item]): Array<unknown> => [key, item]))
     case "forEach": {
       const apply = applyCollectionCallback(runner, args[0], "Map.forEach", node)
       return Effect.gen(function* () {
@@ -404,7 +404,7 @@ const invokeSetMethod = <R>(
     case "values":
       return Effect.sync(() => Array.from(target.set.values()))
     case "entries":
-      return Effect.sync(() => Array.from(target.set.values(), (item) => new ProgramArray([item, item])))
+      return Effect.sync(() => Array.from(target.set.values(), (item): Array<unknown> => [item, item]))
     case "forEach": {
       const apply = applyCollectionCallback(runner, args[0], "Set.forEach", node)
       return Effect.gen(function* () {
@@ -518,27 +518,28 @@ const loadSetRecord = <R>(runner: Runner<R>, source: unknown, name: string, node
       keys: () => Effect.succeed(source.map.keys()),
     })
   }
-  if (!(source instanceof ProgramObject)) {
+  if (source === null || typeof source !== "object" || Values.isValue(source)) {
     throw new InterpreterRuntimeError(`Set.${name} expects a Set-like object.`, node).as("TypeError")
   }
+  const object = source as Record<string, unknown>
   return Effect.gen(function* () {
-    const size = yield* coerceNumericArgument(runner, get(source, "size"), node)
+    const size = yield* coerceNumericArgument(runner, object.size, node)
     if (Number.isNaN(size)) {
       throw new InterpreterRuntimeError(`Set.${name} received a Set-like object with an invalid size.`, node).as(
         "TypeError",
       )
     }
-    const has = get(source, "has")
-    const keys = get(source, "keys")
-    if (!isSupportedCallback(has) || !isSupportedCallback(keys)) {
+    if (!isSupportedCallback(object.has) || !isSupportedCallback(object.keys)) {
       throw new InterpreterRuntimeError(`Set.${name} expects callable 'has' and 'keys' methods.`, node).as("TypeError")
     }
+    const has = object.has
+    const keys = object.keys
     return {
       size: Math.max(Math.trunc(size), 0),
       has: (item: unknown) => Effect.map(runner.invokeCallable(has, [item], node), Boolean),
       keys: () =>
         Effect.flatMap(runner.invokeCallable(keys, [], node), (result) => {
-          if (result instanceof ProgramArray) return Effect.succeed(result.items)
+          if (Array.isArray(result)) return Effect.succeed(result)
           throw new InterpreterRuntimeError(`Set.${name} expected 'keys' to return an iterator.`, node).as("TypeError")
         }),
     }
@@ -603,7 +604,7 @@ const invokeURLSearchParamsMethod = <R>(
     case "values":
       return Effect.sync(() => Array.from(target.params.values()))
     case "entries":
-      return Effect.sync(() => Array.from(target.params.entries(), ([key, value]) => new ProgramArray([key, value])))
+      return Effect.sync(() => Array.from(target.params.entries(), ([key, value]): Array<unknown> => [key, value]))
     case "toString":
       return Effect.sync(() => target.params.toString())
     case "forEach": {
@@ -621,12 +622,11 @@ const invokeURLSearchParamsMethod = <R>(
 
 const invokeArrayMethod = <R>(
   runner: Runner<R>,
-  receiver: ProgramArray,
+  target: Array<unknown>,
   name: string,
   args: Array<unknown>,
   node: AstNode,
 ): Effect.Effect<unknown, unknown, R> => {
-  const target = receiver.items
   const optNumber = (value: unknown, label: string): number | undefined => {
     if (value === undefined) return undefined
     if (typeof value !== "number")
@@ -638,8 +638,9 @@ const invokeArrayMethod = <R>(
       if (args.length > 1 || (args.length === 1 && typeof args[0] !== "string")) {
         throw new InterpreterRuntimeError("Array.join expects zero arguments or one string separator.", node)
       }
+      const input = toProgram(target, "Array.join input") as Array<unknown>
       return Effect.succeed(
-        target.map((item) => coerceToString(item ?? "")).join(args.length === 0 ? "," : (args[0] as string)),
+        input.map((item) => coerceToString(item ?? "")).join(args.length === 0 ? "," : (args[0] as string)),
       )
     }
     case "includes":
@@ -659,15 +660,11 @@ const invokeArrayMethod = <R>(
     case "slice":
       return Effect.succeed(target.slice(optNumber(args[0], "start"), optNumber(args[1], "end")))
     case "concat":
-      return Effect.succeed(target.concat(...args.map((item) => (item instanceof ProgramArray ? item.items : item))))
-    case "flat": {
-      const flatten = (items: Array<unknown>, depth: number): Array<unknown> =>
-        items.flatMap((item) => (item instanceof ProgramArray && depth > 0 ? flatten(item.items, depth - 1) : [item]))
-      return Effect.succeed(flatten(target, optNumber(args[0], "depth") ?? 1))
-    }
+      return Effect.succeed(target.concat(...args))
+    case "flat":
+      return Effect.succeed(target.flat(optNumber(args[0], "depth") ?? 1))
     case "reverse":
-      target.reverse()
-      return Effect.succeed(receiver)
+      return Effect.succeed(target.reverse())
     case "sort": {
       const length = target.length
       const holeCount = Array.from({ length }, (_, index) => Object.hasOwn(target, index)).filter((own) => !own).length
@@ -679,7 +676,7 @@ const invokeArrayMethod = <R>(
         Array.from({ length: holeCount }, (_, index) => itemCount + index).forEach((index) => {
           Reflect.deleteProperty(target, index)
         })
-        return receiver
+        return target
       })
     }
     case "toSorted":
@@ -698,12 +695,12 @@ const invokeArrayMethod = <R>(
     }
     case "push": {
       // Validate all insertions before mutating to avoid partial cyclic updates.
-      for (const item of args) rejectCircularInsertion(receiver, item, "Array.push result", node)
+      for (const item of args) rejectCircularInsertion(target, item, "Array.push result", node)
       target.push(...args)
       return Effect.succeed(target.length)
     }
     case "unshift": {
-      for (const item of args) rejectCircularInsertion(receiver, item, "Array.unshift result", node)
+      for (const item of args) rejectCircularInsertion(target, item, "Array.unshift result", node)
       target.unshift(...args)
       return Effect.succeed(target.length)
     }
@@ -717,7 +714,7 @@ const invokeArrayMethod = <R>(
       if (args.length === 1) return Effect.succeed(target.splice(start))
       const deleteCount = optNumber(args[1], "delete count") ?? 0
       const inserted = args.slice(2)
-      for (const item of inserted) rejectCircularInsertion(receiver, item, "Array.splice result", node)
+      for (const item of inserted) rejectCircularInsertion(target, item, "Array.splice result", node)
       return Effect.succeed(target.splice(start, deleteCount, ...inserted))
     }
     case "toSpliced": {
@@ -734,23 +731,23 @@ const invokeArrayMethod = <R>(
       return Effect.succeed(copied)
     }
     case "fill": {
-      rejectCircularInsertion(receiver, args[0], "Array.fill result", node)
-      target.fill(args[0], optNumber(args[1], "start"), optNumber(args[2], "end"))
-      return Effect.succeed(receiver)
+      rejectCircularInsertion(target, args[0], "Array.fill result", node)
+      return Effect.succeed(target.fill(args[0], optNumber(args[1], "start"), optNumber(args[2], "end")))
     }
     case "copyWithin":
-      target.copyWithin(
-        optNumber(args[0], "target index") ?? 0,
-        optNumber(args[1], "start") ?? 0,
-        optNumber(args[2], "end"),
+      return Effect.succeed(
+        target.copyWithin(
+          optNumber(args[0], "target index") ?? 0,
+          optNumber(args[1], "start") ?? 0,
+          optNumber(args[2], "end"),
+        ),
       )
-      return Effect.succeed(receiver)
     case "keys":
       return Effect.succeed(Array.from(target.keys()))
     case "values":
       return Effect.succeed([...target])
     case "entries":
-      return Effect.succeed(Array.from(target.entries(), ([index, item]) => new ProgramArray([index, item])))
+      return Effect.succeed(Array.from(target.entries(), ([index, item]): Array<unknown> => [index, item]))
   }
 
   const apply = applyCollectionCallback(runner, args[0], `Array.${name}`, node)
@@ -763,7 +760,7 @@ const invokeArrayMethod = <R>(
         values.length = length
         for (let index = 0; index < length; index += 1) {
           if (!(index in target)) continue
-          values[index] = yield* apply([target[index], index, receiver])
+          values[index] = yield* apply([target[index], index, target])
         }
         return values
       }
@@ -771,8 +768,8 @@ const invokeArrayMethod = <R>(
         const values: Array<unknown> = []
         for (let index = 0; index < length; index += 1) {
           if (!(index in target)) continue
-          const mapped = yield* apply([target[index], index, receiver])
-          if (mapped instanceof ProgramArray) values.push(...mapped.items)
+          const mapped = yield* apply([target[index], index, target])
+          if (Array.isArray(mapped)) values.push(...mapped)
           else values.push(mapped)
         }
         return values
@@ -782,36 +779,36 @@ const invokeArrayMethod = <R>(
         for (let index = 0; index < length; index += 1) {
           if (!(index in target)) continue
           const item = target[index]
-          if (yield* apply([item, index, receiver])) values.push(item)
+          if (yield* apply([item, index, target])) values.push(item)
         }
         return values
       }
       case "find":
         for (let index = 0; index < length; index += 1) {
           const item = target[index]
-          if (yield* apply([item, index, receiver])) return item
+          if (yield* apply([item, index, target])) return item
         }
         return undefined
       case "findIndex":
         for (let index = 0; index < length; index += 1) {
-          if (yield* apply([target[index], index, receiver])) return index
+          if (yield* apply([target[index], index, target])) return index
         }
         return -1
       case "some":
         for (let index = 0; index < length; index += 1) {
           if (!(index in target)) continue
-          if (yield* apply([target[index], index, receiver])) return true
+          if (yield* apply([target[index], index, target])) return true
         }
         return false
       case "every":
         for (let index = 0; index < length; index += 1) {
           if (!(index in target)) continue
-          if (!(yield* apply([target[index], index, receiver]))) return false
+          if (!(yield* apply([target[index], index, target]))) return false
         }
         return true
       case "forEach":
         for (let index = 0; index < length; index += 1) {
-          if (index in target) yield* apply([target[index], index, receiver])
+          if (index in target) yield* apply([target[index], index, target])
         }
         return undefined
       case "reduce": {
@@ -828,7 +825,7 @@ const invokeArrayMethod = <R>(
         }
         for (let index = start; index < length; index += 1) {
           if (!(index in target)) continue
-          accumulator = yield* apply([accumulator, target[index], index, receiver])
+          accumulator = yield* apply([accumulator, target[index], index, target])
         }
         return accumulator
       }
@@ -846,19 +843,19 @@ const invokeArrayMethod = <R>(
         }
         for (let index = start; index >= 0; index -= 1) {
           if (!(index in target)) continue
-          accumulator = yield* apply([accumulator, target[index], index, receiver])
+          accumulator = yield* apply([accumulator, target[index], index, target])
         }
         return accumulator
       }
       case "findLast":
         for (let index = length - 1; index >= 0; index -= 1) {
           const item = target[index]
-          if (yield* apply([item, index, receiver])) return item
+          if (yield* apply([item, index, target])) return item
         }
         return undefined
       case "findLastIndex":
         for (let index = length - 1; index >= 0; index -= 1) {
-          if (yield* apply([target[index], index, receiver])) return index
+          if (yield* apply([target[index], index, target])) return index
         }
         return -1
     }

packages/codemode/src/interpreter/model.ts

@@ -1,7 +1,7 @@
-import type { Node } from "acorn"
+import type { BlockStatement, Expression, Node, Pattern } from "acorn"
 import type { Effect } from "effect"
 import type { DiagnosticKind } from "../codemode.js"
-import type { ProgramObject } from "./objects.js"
+import type { SafeObject } from "../data.js"
 import type { Values } from "../values.js"
 
 /** Any parsed node; the interpreter narrows on `type` and reads `loc` for diagnostics. */
@@ -20,10 +20,20 @@ export type StatementResult =
   | { kind: "continue"; label?: string }
 
 export type MemberReference = {
-  target: ProgramObject | Values.RegExp | Values.URL
+  target: SafeObject | Array<unknown> | Values.RegExp | Values.URL
   key: PropertyKey
 }
 
+export class CodeModeFunction {
+  constructor(
+    readonly parameters: ReadonlyArray<Pattern>,
+    readonly body: BlockStatement | Expression,
+    readonly capturedScopes: ReadonlyArray<Map<string, Binding>>,
+    readonly async: boolean,
+    readonly generator: boolean,
+  ) {}
+}
+
 export type GeneratorRequestKind = "next" | "return" | "throw"
 
 export class CodeModeGenerator {

packages/codemode/src/interpreter/objects.ts

@@ -1,145 +0,0 @@
-import type { BlockStatement, Expression, Pattern } from "acorn"
-import { AsyncIteratorSymbol, type Binding, IteratorSymbol } from "./model.js"
-
-/** An object owned by the program: own properties plus a prototype link. */
-export class ProgramObject {
-  readonly props = new Map<PropertyKey, unknown>()
-  constructor(public proto: ProgramObject | null = null) {}
-}
-
-export class ProgramArray extends ProgramObject {
-  constructor(readonly items: Array<unknown> = []) {
-    super()
-  }
-}
-
-export class ProgramError extends ProgramObject {
-  constructor(readonly errorName: string) {
-    super()
-  }
-}
-
-export class ProgramFunction extends ProgramObject {
-  readonly length: number
-  constructor(
-    readonly name: string,
-    readonly parameters: ReadonlyArray<Pattern>,
-    readonly body: BlockStatement | Expression,
-    readonly capturedScopes: ReadonlyArray<Map<string, Binding>>,
-    readonly async: boolean,
-    readonly generator: boolean,
-  ) {
-    super()
-    const optional = parameters.findIndex((p) => p.type === "AssignmentPattern" || p.type === "RestElement")
-    this.length = optional === -1 ? parameters.length : optional
-  }
-}
-
-const MAX_ARRAY_LENGTH = 4_294_967_295
-
-export const parseArrayIndex = (key: string | number): number | undefined => {
-  const property = String(key)
-  if (!/^(0|[1-9]\d*)$/.test(property)) return undefined
-  const index = Number(property)
-  return index < MAX_ARRAY_LENGTH ? index : undefined
-}
-
-const canonical = (key: PropertyKey): string | symbol => (typeof key === "symbol" ? key : String(key))
-
-const index = (target: ProgramObject, key: string | symbol): number | undefined =>
-  target instanceof ProgramArray && typeof key === "string" ? parseArrayIndex(key) : undefined
-
-// Non-enumerable built-in properties: array length, function name and length.
-const builtin = (target: ProgramObject, name: string | symbol): boolean =>
-  (name === "length" && target instanceof ProgramArray) ||
-  ((name === "name" || name === "length") && target instanceof ProgramFunction)
-
-export const hasOwn = (target: ProgramObject, key: PropertyKey): boolean => {
-  const name = canonical(key)
-  const at = index(target, name)
-  if (at !== undefined) return at in (target as ProgramArray).items
-  return builtin(target, name) || target.props.has(name)
-}
-
-export const getOwn = (target: ProgramObject, key: PropertyKey): unknown => {
-  const name = canonical(key)
-  const at = index(target, name)
-  if (at !== undefined) return (target as ProgramArray).items[at]
-  if (target instanceof ProgramArray && name === "length") return target.items.length
-  if (target instanceof ProgramFunction && name === "name") return target.name
-  if (target instanceof ProgramFunction && name === "length") return target.length
-  return target.props.get(name)
-}
-
-export const get = (target: ProgramObject, key: PropertyKey): unknown => {
-  for (let current: ProgramObject | null = target; current !== null; current = current.proto) {
-    if (hasOwn(current, key)) return getOwn(current, key)
-  }
-  return undefined
-}
-
-export const has = (target: ProgramObject, key: PropertyKey): boolean => {
-  for (let current: ProgramObject | null = target; current !== null; current = current.proto) {
-    if (hasOwn(current, key)) return true
-  }
-  return false
-}
-
-export const set = (target: ProgramObject, key: PropertyKey, value: unknown): boolean => {
-  const name = canonical(key)
-  const at = index(target, name)
-  if (at !== undefined) {
-    ;(target as ProgramArray).items[at] = value
-    return true
-  }
-  if (name === "length" && target instanceof ProgramArray) {
-    const length = typeof value === "number" ? value : Number(value)
-    if (!Number.isInteger(length) || length < 0 || length > 4_294_967_295) return false
-    target.items.length = length
-    return true
-  }
-  if (builtin(target, name)) return false
-  target.props.set(name, value)
-  return true
-}
-
-export const remove = (target: ProgramObject, key: PropertyKey): boolean => {
-  const name = canonical(key)
-  const at = index(target, name)
-  if (at !== undefined) return delete (target as ProgramArray).items[at]
-  if (name === "length" && target instanceof ProgramArray) return false
-  if (builtin(target, name)) return true
-  target.props.delete(name)
-  return true
-}
-
-// JS order: array indexes, integer-like keys ascending, other strings, then symbols.
-export const ownKeys = (target: ProgramObject): Array<string | symbol> => {
-  const strings = [...target.props.keys()].filter((key): key is string => typeof key === "string")
-  const symbols = [...target.props.keys()].filter((key): key is symbol => typeof key === "symbol")
-  return [
-    ...(target instanceof ProgramArray ? Object.keys(target.items) : []),
-    ...strings.filter((key) => parseArrayIndex(key) !== undefined).sort((a, b) => Number(a) - Number(b)),
-    ...strings.filter((key) => parseArrayIndex(key) === undefined),
-    ...symbols,
-  ]
-}
-
-export const ownEntries = (target: ProgramObject): Array<[string, unknown]> =>
-  ownKeys(target)
-    .filter((key): key is string => typeof key === "string")
-    .map((key) => [key, getOwn(target, key)])
-
-export const record = (entries: Record<string, unknown>): ProgramObject => {
-  const target = new ProgramObject()
-  for (const [key, value] of Object.entries(entries)) set(target, key, value)
-  return target
-}
-
-export const assign = (target: ProgramObject, source: ProgramObject, skip?: ReadonlySet<PropertyKey>): void => {
-  for (const key of ownKeys(source)) {
-    if (skip?.has(key)) continue
-    if (typeof key === "symbol" && key !== IteratorSymbol && key !== AsyncIteratorSymbol) continue
-    set(target, key, getOwn(source, key))
-  }
-}

packages/codemode/src/interpreter/promises.ts

@@ -1,7 +1,13 @@
 import { Cause, Deferred, Effect, Exit, Fiber, Scope } from "effect"
 import type { Diagnostic } from "../codemode.js"
-import { type AstNode, InterpreterRuntimeError, ProgramThrow, PromiseInstanceMethodReference } from "./model.js"
-import { get, ProgramArray, ProgramFunction, ProgramObject, record } from "./objects.js"
+import type { SafeObject } from "../data.js"
+import {
+  type AstNode,
+  CodeModeFunction,
+  InterpreterRuntimeError,
+  ProgramThrow,
+  PromiseInstanceMethodReference,
+} from "./model.js"
 import { HostFunction, requiresNew, sync } from "./host.js"
 import { caughtErrorValue, normalizeError } from "./errors.js"
 import { typeofValue } from "./references.js"
@@ -105,8 +111,8 @@ export const resolvePromiseValue = <R>(
 ): Effect.Effect<unknown, unknown, R> => {
   if (own?.promise !== undefined && value === own.promise) return Effect.fail(selfResolutionError(node))
   if (value instanceof Values.Promise) return runner.settlePromise(value)
-  if (!(value instanceof ProgramObject)) return Effect.succeed(value)
-  const then = get(value, "then")
+  if (value === null || typeof value !== "object" || !Object.hasOwn(value, "then")) return Effect.succeed(value)
+  const then = (value as SafeObject).then
   if (typeofValue(then) !== "function") return Effect.succeed(value)
 
   return Effect.gen(function* () {
@@ -168,12 +174,10 @@ const invokePromiseMethod = <R>(
       }
 
       if (name === "all") {
-        return new ProgramArray(
-          yield* settleAfterTurn(
-            Effect.all(
-              items.map((item) => Effect.flatten(promises.await(item))),
-              { concurrency: "unbounded" },
-            ),
+        return yield* settleAfterTurn(
+          Effect.all(
+            items.map((item) => Effect.flatten(promises.await(item))),
+            { concurrency: "unbounded" },
           ),
         )
       }
@@ -182,14 +186,19 @@ const invokePromiseMethod = <R>(
         for (const item of items) {
           const exit = yield* promises.await(item)
           if (Exit.isSuccess(exit)) {
-            outcomes.push(record({ status: "fulfilled", value: exit.value }))
+            outcomes.push(Object.assign(Object.create(null) as SafeObject, { status: "fulfilled", value: exit.value }))
             continue
           }
           if (Cause.hasInterruptsOnly(exit.cause)) return yield* Effect.failCause(exit.cause)
-          outcomes.push(record({ status: "rejected", reason: caughtErrorValue(Cause.squash(exit.cause)) }))
+          outcomes.push(
+            Object.assign(Object.create(null) as SafeObject, {
+              status: "rejected",
+              reason: caughtErrorValue(Cause.squash(exit.cause)),
+            }),
+          )
         }
         yield* Effect.yieldNow
-        return new ProgramArray(outcomes)
+        return outcomes
       }
       if (name === "race") {
         if (items.length === 0) {
@@ -244,7 +253,7 @@ const constructPromise = <R>(
   executor: unknown,
   node: AstNode,
 ): Effect.Effect<Values.Promise, unknown, R> => {
-  if (!(executor instanceof ProgramFunction)) {
+  if (!(executor instanceof CodeModeFunction)) {
     throw new InterpreterRuntimeError(
       "new Promise(...) expects an executor function (e.g. new Promise((resolve, reject) => { ... })).",
       node,

packages/codemode/src/interpreter/references.ts

@@ -3,18 +3,20 @@ import { Values } from "../values.js"
 import { HostFunction, HostNamespace } from "./host.js"
 import {
   type AstNode,
+  AsyncIteratorSymbol,
+  CodeModeFunction,
   CodeModeGenerator,
   GeneratorMethodReference,
   InterpreterRuntimeError,
   IntrinsicReference,
+  IteratorSymbol,
   PromiseInstanceMethodReference,
 } from "./model.js"
-import { getOwn, ownKeys, ProgramArray, ProgramFunction, ProgramObject } from "./objects.js"
 
 export const isRuntimeReference = (value: unknown): boolean =>
   value instanceof HostFunction ||
   value instanceof HostNamespace ||
-  value instanceof ProgramFunction ||
+  value instanceof CodeModeFunction ||
   value instanceof CodeModeGenerator ||
   value instanceof GeneratorMethodReference ||
   value instanceof ToolReference ||
@@ -24,8 +26,11 @@ export const isRuntimeReference = (value: unknown): boolean =>
   Values.isValue(value)
 
 function* childValues(value: object): Generator {
-  if (!(value instanceof ProgramObject)) return
-  for (const key of ownKeys(value)) yield getOwn(value, key)
+  for (const key of Reflect.ownKeys(value)) {
+    if (!Object.prototype.propertyIsEnumerable.call(value, key)) continue
+    if (typeof key === "symbol" && key !== AsyncIteratorSymbol && key !== IteratorSymbol) continue
+    yield Reflect.get(value, key)
+  }
 }
 
 // Depth-first search over a value tree. `match` stops the walk; `skip` prunes a subtree without matching it.
@@ -74,7 +79,7 @@ export const rejectCircularInsertion = (
 
 export const describeValue = (value: unknown): string => {
   if (value === null) return "null"
-  if (value instanceof ProgramArray) return "an array"
+  if (Array.isArray(value)) return "an array"
   if (value instanceof Values.Promise) return "an un-awaited Promise"
   if (value instanceof ToolReference) return "a tool reference"
   if (value instanceof Values.Date) return "a Date"
@@ -92,7 +97,7 @@ export const describeValue = (value: unknown): string => {
 export const typeofValue = (value: unknown): string => {
   if (
     value instanceof HostFunction ||
-    value instanceof ProgramFunction ||
+    value instanceof CodeModeFunction ||
     value instanceof GeneratorMethodReference ||
     value instanceof IntrinsicReference ||
     value instanceof PromiseInstanceMethodReference
@@ -103,3 +108,12 @@ export const typeofValue = (value: unknown): string => {
   if (value instanceof ToolReference) return value.path.length > 0 ? "function" : "object"
   return typeof value
 }
+
+const MAX_ARRAY_LENGTH = 4_294_967_295
+
+export const parseArrayIndex = (key: string | number): number | undefined => {
+  const property = String(key)
+  if (!/^(0|[1-9]\d*)$/.test(property)) return undefined
+  const index = Number(property)
+  return index < MAX_ARRAY_LENGTH ? index : undefined
+}

packages/codemode/src/interpreter/runner.ts

@@ -2,8 +2,7 @@ import { Effect, Exit } from "effect"
 import { Values } from "../values.js"
 import { coerceToString } from "../stdlib/value.js"
 import { HostFunction } from "./host.js"
-import { type AstNode, InterpreterRuntimeError, IntrinsicReference } from "./model.js"
-import { get, has, ProgramFunction, ProgramObject } from "./objects.js"
+import { type AstNode, CodeModeFunction, InterpreterRuntimeError, IntrinsicReference } from "./model.js"
 import { typeofValue } from "./references.js"
 
 export type IteratorCursor<R> = {
@@ -13,7 +12,7 @@ export type IteratorCursor<R> = {
 
 /** Everything a host function needs to call back into the program. */
 export type Runner<R> = {
-  readonly invokeFunction: (fn: ProgramFunction, args: Array<unknown>) => Effect.Effect<unknown, unknown, R>
+  readonly invokeFunction: (fn: CodeModeFunction, args: Array<unknown>) => Effect.Effect<unknown, unknown, R>
   readonly invokeCallable: (
     callable: unknown,
     args: Array<unknown>,
@@ -43,14 +42,13 @@ export const toPrimitive = <R>(
   if (Values.isValue(value)) {
     return Effect.succeed(value instanceof Values.Date && hint === "number" ? value.time : coerceToString(value))
   }
-  if (!(value instanceof ProgramObject)) return Effect.succeed(value)
+  const object = value as Record<string, unknown>
   const order = hint === "number" ? ["valueOf", "toString"] : ["toString", "valueOf"]
   return Effect.gen(function* () {
     for (const method of order) {
-      if (method === "toString" && !has(value, "toString")) return coerceToString(value)
-      const callable = get(value, method)
-      if (typeofValue(callable) !== "function") continue
-      const result = yield* runner.invokeCallable(callable, [], node)
+      if (method === "toString" && !Object.hasOwn(object, "toString")) return coerceToString(value)
+      if (!Object.hasOwn(object, method) || typeofValue(object[method]) !== "function") continue
+      const result = yield* runner.invokeCallable(object[method], [], node)
       if (result === null || (typeof result !== "object" && typeof result !== "function")) return result
     }
     throw new InterpreterRuntimeError("Cannot convert object to primitive value.", node).as("TypeError")
@@ -61,10 +59,10 @@ export const toPrimitive = <R>(
 // 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 type SupportedCallback = ProgramFunction | HostFunction<unknown> | IntrinsicReference
+export type SupportedCallback = CodeModeFunction | HostFunction<unknown> | IntrinsicReference
 
 export const isSupportedCallback = (value: unknown): value is SupportedCallback =>
-  value instanceof ProgramFunction ||
+  value instanceof CodeModeFunction ||
   (value instanceof HostFunction && value.callback) ||
   value instanceof IntrinsicReference
 

packages/codemode/src/interpreter/runtime.ts

@@ -1,7 +1,6 @@
 import type {
   ArrayExpression,
   ArrayPattern,
-  AssignmentPattern,
   ArrowFunctionExpression,
   AssignmentExpression,
   AssignmentProperty,
@@ -42,12 +41,13 @@ import type {
   YieldExpression,
 } from "acorn"
 import { Cause, Deferred, Effect, Exit } from "effect"
-import { ToolRuntimeError, toProgram } from "../data.js"
+import { ToolRuntimeError, type SafeObject, toProgram } from "../data.js"
 import { ToolReference } from "../tool-runtime.js"
 import {
   type AstNode,
   AsyncIteratorSymbol,
   type Binding,
+  CodeModeFunction,
   CodeModeGenerator,
   ComputedValue,
   GeneratorMethodReference,
@@ -55,7 +55,9 @@ import {
   type GeneratorRequestKind,
   IntrinsicReference,
   InterpreterRuntimeError,
+  isRecord,
   IteratorSymbol,
+  IteratorSymbols,
   type MemberReference,
   OptionalShortCircuit,
   PromiseInstanceMethodReference,
@@ -64,28 +66,16 @@ import {
   unsupportedSyntax,
 } from "./model.js"
 import { caughtErrorValue } from "./errors.js"
-import { globals, type Host } from "./globals.js"
+import { globals } from "./globals.js"
 import { HostFunction, HostNamespace } from "./host.js"
 import { invokeIntrinsic } from "./methods.js"
-import {
-  assign,
-  get,
-  has,
-  ownKeys,
-  parseArrayIndex,
-  ProgramArray,
-  ProgramFunction,
-  ProgramObject,
-  record,
-  remove,
-  set,
-} from "./objects.js"
 import { preserveConsumerError, type Runner } from "./runner.js"
 import { invokePromiseInstanceMethod, PromiseRuntime, resolvePromise, resolvePromiseValue } from "./promises.js"
 import {
   containsOpaqueReference,
   describeValue,
   isRuntimeReference,
+  parseArrayIndex,
   rejectCircularInsertion,
   typeofValue,
 } from "./references.js"
@@ -128,11 +118,14 @@ const calleeDescription = (callee: Expression | Super | undefined): string => {
   return "The called value"
 }
 
+const hasOwn = (value: unknown, key: PropertyKey): boolean =>
+  value !== null && typeof value === "object" && Object.hasOwn(value, key)
+
 const constructorName = (value: unknown): string | undefined => {
   if (typeof value === "string") return "String"
   if (typeof value === "number") return "Number"
   if (typeof value === "boolean") return "Boolean"
-  if (value instanceof ProgramArray) return "Array"
+  if (Array.isArray(value)) return "Array"
   if (value instanceof Values.Date) return "Date"
   if (value instanceof Values.RegExp) return "RegExp"
   if (value instanceof Values.Map) return "Map"
@@ -140,7 +133,7 @@ const constructorName = (value: unknown): string | undefined => {
   if (value instanceof Values.URL) return "URL"
   if (value instanceof Values.URLSearchParams) return "URLSearchParams"
   if (value instanceof Values.Promise) return "Promise"
-  if (!(value instanceof ProgramObject) || value instanceof ProgramFunction) return undefined
+  if (value === null || typeof value !== "object" || isRuntimeReference(value)) return undefined
   return errorBrandName(value) ?? "Object"
 }
 
@@ -237,7 +230,7 @@ const loopDeclaration = (left: VariableDeclaration | Pattern, statement: "for...
 }
 
 type CustomIterator = {
-  iterator: ProgramObject | CodeModeGenerator
+  iterator: SafeObject | CodeModeGenerator
   next: unknown
   asynchronous: boolean
 }
@@ -254,6 +247,13 @@ const isOpaqueMemberReference = (value: unknown): value is OpaqueMemberReference
   value instanceof IntrinsicReference ||
   value instanceof GeneratorMethodReference
 
+const copyIteratorSymbols = (source: object, target: object, consumed?: ReadonlySet<PropertyKey>): void => {
+  for (const symbol of IteratorSymbols) {
+    if (!consumed?.has(symbol) && Object.hasOwn(source, symbol))
+      Reflect.set(target, symbol, Reflect.get(source, symbol))
+  }
+}
+
 type GeneratorRequest = {
   kind: GeneratorRequestKind
   value: unknown
@@ -285,7 +285,6 @@ export class Runtime<R> {
     readonly toolKeys: (path: ReadonlyArray<string>) => ReadonlyArray<string>,
     readonly promises: PromiseRuntime<R>,
     readonly logs: Array<string> = [],
-    extraGlobals: (host: Host<R>) => ReadonlyArray<readonly [string, unknown]> = () => [],
   ) {
     const globalScope = new Map<string, Binding>()
     // Calling back into the program never reads frame state, so any frame serves; the root is always alive.
@@ -296,7 +295,7 @@ export class Runtime<R> {
       settlePromise: (promise) => this.root.settlePromise(promise),
       syncIterator: (value, node) => this.root.syncIterator(value, node),
     }
-    this.builtins = new Map([...globals(this), ...extraGlobals(this)])
+    this.builtins = new Map(globals(this))
     for (const [name, value] of this.builtins) globalScope.set(name, { mutable: false, value })
   }
 
@@ -435,19 +434,8 @@ class Frame<R> {
     }).pipe(Effect.ensuring(Effect.sync(() => self.scopes.pop())))
   }
 
-  private createFunction(
-    node: FunctionDeclaration | FunctionExpression | ArrowFunctionExpression,
-    name = node.type === "ArrowFunctionExpression" ? "" : (node.id?.name ?? ""),
-  ): ProgramFunction {
-    return new ProgramFunction(name, node.params, node.body, this.scopes.capture(), node.async, node.generator)
-  }
-
-  // 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> {
-    if (node.type === "ArrowFunctionExpression" || (node.type === "FunctionExpression" && !node.id)) {
-      return Effect.sync(() => this.createFunction(node, name))
-    }
-    return this.evaluateExpression(node)
+  private createFunction(node: FunctionDeclaration | FunctionExpression | ArrowFunctionExpression): CodeModeFunction {
+    return new CodeModeFunction(node.params, node.body, this.scopes.capture(), node.async, node.generator)
   }
 
   private hoistFunctions(statements: ReadonlyArray<Statement | ModuleDeclaration>): void {
@@ -734,26 +722,22 @@ class Frame<R> {
   }
 
   syncIterator(value: unknown, node: AstNode) {
-    const iterator =
-      value instanceof ProgramArray
-        ? value.items[Symbol.iterator]()
-        : typeof value === "string"
-          ? value[Symbol.iterator]()
-          : value instanceof Values.Map
-            ? value.map.entries()
-            : value instanceof Values.Set
-              ? value.set.values()
-              : value instanceof Values.URLSearchParams
-                ? value.params.entries()
-                : undefined
+    const iterator = Array.isArray(value)
+      ? value[Symbol.iterator]()
+      : typeof value === "string"
+        ? value[Symbol.iterator]()
+        : value instanceof Values.Map
+          ? value.map.entries()
+          : value instanceof Values.Set
+            ? value.set.values()
+            : value instanceof Values.URLSearchParams
+              ? value.params.entries()
+              : undefined
     if (iterator !== undefined) {
       return Effect.succeed({
         next: Effect.sync(() => {
           const step = iterator.next()
-          return {
-            done: Boolean(step.done),
-            value: Array.isArray(step.value) ? new ProgramArray(step.value) : step.value,
-          }
+          return { done: Boolean(step.done), value: step.value }
         }),
         close: Effect.void,
       })
@@ -778,9 +762,9 @@ class Frame<R> {
         asynchronous: value.asynchronous,
       })
     }
-    if (!(value instanceof ProgramObject)) return Effect.undefined
-    const asyncMethod = allowAsync ? get(value, AsyncIteratorSymbol) : undefined
-    const method = asyncMethod ?? get(value, IteratorSymbol)
+    if (!isRecord(value) || isRuntimeReference(value)) return Effect.undefined
+    const asyncMethod = allowAsync ? Reflect.get(value, AsyncIteratorSymbol) : undefined
+    const method = asyncMethod ?? Reflect.get(value, IteratorSymbol)
     if (method === undefined || method === null) return Effect.undefined
     const self = this
     return Effect.map(
@@ -792,7 +776,7 @@ class Frame<R> {
           next:
             object instanceof CodeModeGenerator
               ? new GeneratorMethodReference(object, "next")
-              : self.requireIteratorMethod(get(object, "next"), "Iterator next", node),
+              : self.requireIteratorMethod(object.next, "Iterator next", node),
           asynchronous: asyncMethod !== undefined && asyncMethod !== null,
         }
       },
@@ -808,7 +792,7 @@ class Frame<R> {
           "Iterator next() result",
           node,
         )
-        return { done: Boolean(get(object, "done")), value: get(object, "value") }
+        return { done: Boolean(object.done), value: object.value }
       }
 
       const called = yield* Effect.exit(self.invokeCallable(iterator.next, [], node))
@@ -819,7 +803,7 @@ class Frame<R> {
       const captured = yield* Effect.exit(
         Effect.sync(() => {
           const object = self.requireIteratorObject(called.value, "Iterator next() result", node)
-          return { done: Boolean(get(object, "done")), value: get(object, "value") }
+          return { done: Boolean(object.done), value: object.value }
         }),
       )
       if (!Exit.isSuccess(captured)) {
@@ -839,7 +823,7 @@ class Frame<R> {
     const close =
       iterator.iterator instanceof CodeModeGenerator
         ? new GeneratorMethodReference(iterator.iterator, "return")
-        : get(iterator.iterator, "return")
+        : iterator.iterator.return
     if (close === undefined || close === null) return iterator.asynchronous || !awaiting ? Effect.void : Effect.yieldNow
     const self = this
     return Effect.gen(function* () {
@@ -859,7 +843,7 @@ class Frame<R> {
         return yield* Effect.failCause(called.cause)
       }
       const captured = yield* Effect.exit(
-        Effect.sync(() => get(self.requireIteratorObject(called.value, "Iterator return() result", node), "value")),
+        Effect.sync(() => self.requireIteratorObject(called.value, "Iterator return() result", node).value),
       )
       if (!Exit.isSuccess(captured)) {
         if (awaiting) yield* Effect.yieldNow
@@ -869,12 +853,12 @@ class Frame<R> {
     })
   }
 
-  private requireIteratorObject(value: unknown, context: string, node: AstNode): ProgramObject {
-    if (value instanceof ProgramObject) return value
+  private requireIteratorObject(value: unknown, context: string, node: AstNode): SafeObject {
+    if (isRecord(value) && !isRuntimeReference(value)) return value
     throw new InterpreterRuntimeError(`${context} must be an object.`, node).as("TypeError")
   }
 
-  private requireIterator(value: unknown, node: AstNode): ProgramObject | CodeModeGenerator {
+  private requireIterator(value: unknown, node: AstNode): SafeObject | CodeModeGenerator {
     return value instanceof CodeModeGenerator
       ? value
       : this.requireIteratorObject(value, "Iterator method result", node)
@@ -889,7 +873,7 @@ class Frame<R> {
   private enumerableKeys(value: unknown, node: AstNode): Array<string> {
     if (value instanceof ToolReference) return [...this.runtime.toolKeys(value.path)]
     if (value === null || value === undefined) return []
-    return ownKeys(enumerableSource("for...in", value, node)).filter((key): key is string => typeof key === "string")
+    return Object.keys(enumerableSource("for...in", value, node))
   }
 
   private evaluateForInStatement(
@@ -1035,14 +1019,11 @@ class Frame<R> {
 
         const init = declaration.init
         // `var x` alone is a no-op: the binding was hoisted on function entry.
-        const id = declaration.id
-        const evaluate = (init: Expression) =>
-          id.type === "Identifier" ? self.evaluateNamed(init, id.name) : self.evaluateExpression(init)
         if (kind === "var") {
-          if (init) yield* self.assignPattern(id, yield* evaluate(init), declaration)
+          if (init) yield* self.assignPattern(declaration.id, yield* self.evaluateExpression(init), declaration)
           continue
         }
-        const value = init ? yield* evaluate(init) : undefined
+        const value = init ? yield* self.evaluateExpression(init) : undefined
         yield* self.declarePattern(declaration.id, value, kind !== "const", declaration, true)
       }
     })
@@ -1065,13 +1046,13 @@ class Frame<R> {
       }
 
       if (pattern.type === "AssignmentPattern") {
-        const resolved = value === undefined ? yield* self.evaluateDefault(pattern) : value
+        const resolved = value === undefined ? yield* self.evaluateExpression(pattern.right) : value
         yield* self.declarePattern(pattern.left, resolved, mutable, node, initialize)
         return
       }
 
       if (pattern.type === "ObjectPattern") {
-        if (!(value instanceof ProgramObject)) {
+        if (value === null || typeof value !== "object" || isRuntimeReference(value)) {
           throw new InterpreterRuntimeError(
             `Object destructuring requires a data object or array value, received ${describeValue(value)}.`,
             pattern,
@@ -1082,8 +1063,11 @@ class Frame<R> {
         const consumed = new Set<PropertyKey>()
         for (const property of pattern.properties) {
           if (property.type === "RestElement") {
-            const rest = new ProgramObject()
-            assign(rest, value, consumed)
+            const rest: SafeObject = Object.create(null) as SafeObject
+            for (const [key, item] of Object.entries(value as SafeObject)) {
+              if (!consumed.has(key)) rest[key] = item
+            }
+            copyIteratorSymbols(value, rest, consumed)
             yield* self.declarePattern(property.argument, rest, mutable, property, initialize)
             continue
           }
@@ -1092,7 +1076,7 @@ class Frame<R> {
           consumed.add(typeof key === "symbol" ? key : String(key))
           yield* self.declarePattern(
             property.value,
-            self.destructuringPropertyValue(value, key),
+            self.destructuringPropertyValue(value as SafeObject | Array<unknown>, key),
             mutable,
             property,
             initialize,
@@ -1125,13 +1109,13 @@ class Frame<R> {
       }
 
       if (pattern.type === "AssignmentPattern") {
-        const resolved = value === undefined ? yield* self.evaluateDefault(pattern) : value
+        const resolved = value === undefined ? yield* self.evaluateExpression(pattern.right) : value
         yield* self.assignPattern(pattern.left, resolved, node)
         return
       }
 
       if (pattern.type === "ObjectPattern") {
-        if (!(value instanceof ProgramObject)) {
+        if (value === null || typeof value !== "object" || isRuntimeReference(value)) {
           throw new InterpreterRuntimeError(
             `Object destructuring requires a data object or array value, received ${describeValue(value)}.`,
             pattern,
@@ -1139,17 +1123,21 @@ class Frame<R> {
           )
         }
 
+        const source = value as SafeObject | Array<unknown>
         const consumed = new Set<PropertyKey>()
         for (const property of pattern.properties) {
           if (property.type === "RestElement") {
-            const rest = new ProgramObject()
-            assign(rest, value, consumed)
+            const rest: SafeObject = Object.create(null) as SafeObject
+            for (const [key, item] of Object.entries(source)) {
+              if (!consumed.has(key)) rest[key] = item
+            }
+            copyIteratorSymbols(source, rest, consumed)
             yield* self.assignPattern(property.argument, rest, property)
             continue
           }
           const key = yield* self.destructuringPropertyKey(property)
           consumed.add(typeof key === "symbol" ? key : String(key))
-          yield* self.assignPattern(property.value, self.destructuringPropertyValue(value, key), property)
+          yield* self.assignPattern(property.value, self.destructuringPropertyValue(source, key), property)
         }
         return
       }
@@ -1164,12 +1152,6 @@ class Frame<R> {
     })
   }
 
-  private evaluateDefault(pattern: AssignmentPattern): Effect.Effect<unknown, unknown, R> {
-    return pattern.left.type === "Identifier"
-      ? this.evaluateNamed(pattern.right, pattern.left.name)
-      : this.evaluateExpression(pattern.right)
-  }
-
   private destructureArrayPattern(
     pattern: ArrayPattern,
     value: unknown,
@@ -1189,7 +1171,7 @@ class Frame<R> {
           if (element === null) continue
           yield* consume(
             element.type === "RestElement" ? element.argument : element,
-            element.type === "RestElement" ? new ProgramArray() : undefined,
+            element.type === "RestElement" ? [] : undefined,
             element,
           )
           if (element.type === "RestElement") return
@@ -1206,7 +1188,7 @@ class Frame<R> {
             done = next.done
             if (!done) rest.push(next.value)
           }
-          yield* consume(element.argument, new ProgramArray(rest), element)
+          yield* consume(element.argument, rest, element)
           return
         }
         const consumed = consume(element, step.done ? undefined : step.value, pattern)
@@ -1229,9 +1211,11 @@ class Frame<R> {
     throw unsupportedSyntax(keyNode.type, keyNode)
   }
 
-  private destructuringPropertyValue(source: ProgramObject, key: PropertyKey): unknown {
-    if (!(source instanceof ProgramArray)) return get(source, key)
-    if (has(source, key)) return get(source, key)
+  private destructuringPropertyValue(source: SafeObject | Array<unknown>, key: PropertyKey): unknown {
+    if (!Array.isArray(source)) return Reflect.get(source, key)
+    if (key === "length") return source.length
+    if (typeof key === "number") return source[key]
+    if (Object.hasOwn(source, key)) return Reflect.get(source, key)
     if (typeof key === "string" && arrayMethods.has(key)) return new IntrinsicReference(source, key)
     return undefined
   }
@@ -1309,7 +1293,7 @@ class Frame<R> {
         // otherwise; say `new` is unsupported for them and point at the plain call.
         const name = calleeDescription(node.callee)
         const message =
-          callee instanceof ProgramFunction
+          callee instanceof CodeModeFunction
             ? `${name} cannot be constructed: user-defined constructors and classes are not supported. Call it as a function that returns a plain object instead.`
             : callee instanceof HostFunction
               ? `new ${name}(...) is not supported; call ${name}(...) without new instead.`
@@ -1337,9 +1321,6 @@ class Frame<R> {
   private applyBinaryOperator(operator: string, lhs: unknown, rhs: unknown, node: AstNode): unknown {
     if (operator === "===") return lhs === rhs
     if (operator === "!==") return lhs !== rhs
-    if (operator === "in" && rhs instanceof ProgramObject && !containsOpaqueReference(lhs)) {
-      return has(rhs, lhs !== null && typeof lhs === "object" ? coerceToString(lhs) : (lhs as PropertyKey))
-    }
     if (containsOpaqueReference(lhs) || containsOpaqueReference(rhs)) {
       throw new InterpreterRuntimeError("Binary operators require data values.", node, "InvalidDataValue")
     }
@@ -1392,10 +1373,11 @@ class Frame<R> {
       case ">>>":
         return (l as number) >>> (r as number)
       case "in":
-        if (!(rhs instanceof ProgramObject)) {
+        if (rhs === null || typeof rhs !== "object") {
           throw new InterpreterRuntimeError("The 'in' operator requires a data object on the right-hand side.", node)
         }
-        return has(rhs, coerceOperand(lhs) as PropertyKey)
+        // Never expose properties inherited from host prototypes.
+        return Object.hasOwn(rhs as object, coerceOperand(lhs) as PropertyKey)
       default:
         throw new InterpreterRuntimeError(`Unsupported binary operator '${operator}'.`, node)
     }
@@ -1472,7 +1454,7 @@ class Frame<R> {
           const next = toProgram(self.applyCompoundAssignment(operator, current, rightValue, node), "Assignment result")
           return self.scopes.set(name, next, left)
         }
-        const rightValue = yield* self.evaluateNamed(node.right, name)
+        const rightValue = yield* self.evaluateExpression(node.right)
         return self.scopes.set(name, rightValue, left)
       }
       if (left.type === "MemberExpression") {
@@ -1504,7 +1486,7 @@ class Frame<R> {
       return Effect.gen(function* () {
         const current = self.scopes.get(name, left)
         if (!shouldAssign(current)) return current
-        const rightValue = yield* self.evaluateNamed(node.right, name)
+        const rightValue = yield* self.evaluateExpression(node.right)
         return self.scopes.set(name, rightValue, left)
       })
     }
@@ -1593,7 +1575,7 @@ class Frame<R> {
         }
         return yield* self.createToolCallPromise(callable.path, args)
       }
-      if (callable instanceof ProgramFunction) {
+      if (callable instanceof CodeModeFunction) {
         return yield* self.invokeFunction(callable, args)
       }
       if (callable instanceof GeneratorMethodReference) {
@@ -1644,7 +1626,7 @@ class Frame<R> {
     })
   }
 
-  invokeFunction(fn: ProgramFunction, args: Array<unknown>): Effect.Effect<unknown, unknown, R> {
+  invokeFunction(fn: CodeModeFunction, args: Array<unknown>): Effect.Effect<unknown, unknown, R> {
     const invocation = new Frame(this.runtime, new ScopeStack([...fn.capturedScopes, new Map()]))
     const run = Effect.gen(function* () {
       // Seed all parameters first so defaults cannot fall through to same-named outer bindings.
@@ -1656,13 +1638,7 @@ class Frame<R> {
       }
       for (const [index, parameter] of fn.parameters.entries()) {
         if (parameter.type === "RestElement") {
-          yield* invocation.declarePattern(
-            parameter.argument,
-            new ProgramArray(args.slice(index)),
-            true,
-            parameter,
-            true,
-          )
+          yield* invocation.declarePattern(parameter.argument, args.slice(index), true, parameter, true)
           break
         }
         yield* invocation.declarePattern(parameter, args[index], true, parameter, true)
@@ -1714,12 +1690,12 @@ class Frame<R> {
       }
       if (state.completed) {
         if (kind === "throw") return Effect.fail(new ProgramThrow(value))
-        return Effect.succeed(record({ value: kind === "return" ? value : undefined, done: true }))
+        return Effect.succeed({ value: kind === "return" ? value : undefined, done: true })
       }
       if (!state.started && kind !== "next") {
         state.completed = true
         if (kind === "throw") return Effect.fail(new ProgramThrow(value))
-        return Effect.succeed(record({ value, done: true }))
+        return Effect.succeed({ value, done: true })
       }
 
       state.pending.push(request)
@@ -1749,7 +1725,7 @@ class Frame<R> {
           if (active) {
             Deferred.doneUnsafe(
               active.response,
-              Exit.isSuccess(exit) ? Exit.succeed(record({ value: exit.value, done: true })) : exit,
+              Exit.isSuccess(exit) ? Exit.succeed({ value: exit.value, done: true }) : exit,
             )
           }
           yield* invocation.completeGeneratorRequests(state, asynchronous)
@@ -1776,13 +1752,13 @@ class Frame<R> {
           const resolved = yield* Effect.exit(self.awaitValue(pending.value))
           Deferred.doneUnsafe(
             pending.response,
-            Exit.isSuccess(resolved) ? Exit.succeed(record({ value: resolved.value, done: true })) : resolved,
+            Exit.isSuccess(resolved) ? Exit.succeed({ value: resolved.value, done: true }) : resolved,
           )
           continue
         }
         Deferred.doneUnsafe(
           pending.response,
-          Exit.succeed(record({ value: pending.kind === "return" ? pending.value : undefined, done: true })),
+          Exit.succeed({ value: pending.kind === "return" ? pending.value : undefined, done: true }),
         )
       }
     })
@@ -1827,7 +1803,7 @@ class Frame<R> {
   private suspendGenerator(value: unknown, node: AstNode): Effect.Effect<unknown, unknown, R> {
     const state = this.generatorState
     if (!state?.active) throw new InterpreterRuntimeError("Generator has no active request.", node)
-    Deferred.doneUnsafe(state.active.response, Exit.succeed(record({ value, done: false })))
+    Deferred.doneUnsafe(state.active.response, Exit.succeed({ value, done: false }))
     state.active = undefined
     return Effect.flatMap(this.takeGeneratorRequest(state), (request) => {
       state.active = request
@@ -1843,7 +1819,7 @@ class Frame<R> {
     const self = this
     return Effect.gen(function* () {
       if (
-        value instanceof ProgramArray ||
+        Array.isArray(value) ||
         typeof value === "string" ||
         value instanceof Values.Map ||
         value instanceof Values.Set ||
@@ -1884,7 +1860,7 @@ class Frame<R> {
             ? iterator.next
             : iterator.iterator instanceof CodeModeGenerator
               ? new GeneratorMethodReference(iterator.iterator, kind)
-              : get(iterator.iterator, kind)
+              : iterator.iterator[kind]
         if (method === undefined || method === null) {
           if (kind === "return") return yield* Effect.fail(new GeneratorReturn(input))
           yield* self.closeIterator(iterator, node, self.generatorAsync)
@@ -1902,11 +1878,11 @@ class Frame<R> {
           `Iterator ${kind}() result`,
           node,
         )
-        const done = Boolean(get(result, "done"))
+        const done = Boolean(result.done)
         const resultValue: unknown =
           self.generatorAsync && !iterator.asynchronous
-            ? yield* self.awaitAsyncFromSyncValue(iterator, get(result, "value"), node, kind !== "return" && !done)
-            : get(result, "value")
+            ? yield* self.awaitAsyncFromSyncValue(iterator, result.value, node, kind !== "return" && !done)
+            : result.value
         if (done) {
           if (kind === "return") return yield* Effect.fail(new GeneratorReturn(resultValue))
           return resultValue
@@ -1928,15 +1904,17 @@ class Frame<R> {
     })
   }
 
-  private evaluateObjectExpression(node: ObjectExpression): Effect.Effect<ProgramObject, unknown, R> {
-    const objectValue = new ProgramObject()
+  private evaluateObjectExpression(node: ObjectExpression): Effect.Effect<Record<string, unknown>, unknown, R> {
+    const objectValue: Record<string, unknown> = Object.create(null) as Record<string, unknown>
     const self = this
     return Effect.gen(function* () {
       for (const property of node.properties) {
         if (property.type === "SpreadElement") {
           const spread = yield* self.evaluateExpression(property.argument)
           if (spread === null || spread === undefined) continue
-          assign(objectValue, enumerableSource("Object spread", spread, property))
+          const from = enumerableSource("Object spread", spread, property)
+          for (const [key, value] of Object.entries(from)) objectValue[key] = value
+          if (typeof from === "object") copyIteratorSymbols(from, objectValue)
           continue
         }
 
@@ -1958,20 +1936,14 @@ class Frame<R> {
           throw new InterpreterRuntimeError("Unsupported object property key shape.", keyNode)
         }
 
-        const name =
-          key === IteratorSymbol
-            ? "[Symbol.iterator]"
-            : key === AsyncIteratorSymbol
-              ? "[Symbol.asyncIterator]"
-              : String(key)
-        set(objectValue, key, yield* self.evaluateNamed(property.value, name))
+        Reflect.set(objectValue, key, yield* self.evaluateExpression(property.value))
       }
 
       return objectValue
     })
   }
 
-  private evaluateArrayExpression(node: ArrayExpression): Effect.Effect<ProgramArray, unknown, R> {
+  private evaluateArrayExpression(node: ArrayExpression): Effect.Effect<Array<unknown>, unknown, R> {
     const values: Array<unknown> = []
 
     const self = this
@@ -1996,7 +1968,7 @@ class Frame<R> {
           values.push(yield* self.evaluateExpression(element))
         }
       }
-      return new ProgramArray(values)
+      return values
     })
   }
 
@@ -2083,11 +2055,7 @@ class Frame<R> {
       }
 
       // Values have no prototype chain, so `.constructor` resolves to the owning built-in directly.
-      if (
-        operation === "read" &&
-        key === "constructor" &&
-        !(objectValue instanceof ProgramObject && has(objectValue, key))
-      ) {
+      if (operation === "read" && key === "constructor" && !hasOwn(objectValue, key)) {
         const name = constructorName(objectValue)
         if (name !== undefined) return new ComputedValue(self.runtime.builtins.get(name))
       }
@@ -2168,8 +2136,6 @@ class Frame<R> {
         return new ComputedValue(undefined)
       }
 
-      if (objectValue instanceof ProgramObject) return { target: objectValue, key }
-
       if (isRuntimeReference(objectValue)) {
         throw new InterpreterRuntimeError(
           `Cannot read properties of ${describeValue(objectValue)}; only data values expose properties.`,
@@ -2177,27 +2143,42 @@ class Frame<R> {
           "InvalidDataValue",
         )
       }
-      throw new InterpreterRuntimeError("Cannot access a property on a non-object value.", objectNode)
+
+      if (typeof objectValue !== "object" || objectValue === null) {
+        throw new InterpreterRuntimeError("Cannot access a property on a non-object value.", objectNode)
+      }
+
+      if (Array.isArray(objectValue)) {
+        if (operation === "delete") return { target: objectValue, key }
+        const index = typeof key === "symbol" ? undefined : parseArrayIndex(key)
+        if (key !== "length" && !(typeof key === "string" && arrayMethods.has(key)) && index === undefined) {
+          if (typeof key === "string" && Object.hasOwn(objectValue, key)) {
+            return new ComputedValue((objectValue as Record<string, unknown> & Array<unknown>)[key])
+          }
+          return new ComputedValue(undefined)
+        }
+        return { target: objectValue, key: index ?? key }
+      }
+
+      return { target: objectValue as SafeObject, key }
     })
   }
 
   private readMember(node: MemberExpression): Effect.Effect<unknown, unknown, R> {
-    const self = this
     return Effect.map(this.getMemberReference(node), (reference) => {
       if (reference === OptionalShortCircuit) return OptionalShortCircuit
       if (reference instanceof ComputedValue) return reference.value
       if (reference === undefined || isOpaqueMemberReference(reference)) return reference
-      const value = self.readReferenceValue(reference, reference.key)
-      if (
-        value === undefined &&
-        reference.target instanceof ProgramArray &&
-        typeof reference.key === "string" &&
-        arrayMethods.has(reference.key) &&
-        !has(reference.target, reference.key)
-      ) {
-        return new IntrinsicReference(reference.target, reference.key)
+      if (Array.isArray(reference.target)) {
+        if (reference.key === "length") return reference.target.length
+        if (typeof reference.key === "string") return new IntrinsicReference(reference.target, reference.key)
+        return Reflect.get(reference.target, reference.key)
       }
-      return value
+      if (reference.target instanceof Values.RegExp) return reference.target.lastIndex
+      if (reference.target instanceof Values.URL) {
+        return Reflect.get(reference.target.url, reference.key)
+      }
+      return Reflect.get(reference.target, reference.key)
     })
   }
 
@@ -2223,7 +2204,7 @@ class Frame<R> {
       if (reference.target instanceof Values.RegExp) {
         return Reflect.deleteProperty(reference.target.regex, reference.key)
       }
-      return remove(reference.target, reference.key)
+      return Reflect.deleteProperty(reference.target, reference.key)
     })
   }
 
@@ -2243,6 +2224,12 @@ class Frame<R> {
       ) {
         throw new InterpreterRuntimeError("Only data fields may be assigned.", node)
       }
+      if (Array.isArray(reference.target)) {
+        if (reference.key === "length") throw new InterpreterRuntimeError("Array length cannot be assigned.", node)
+        if (typeof reference.key === "string" && arrayMethods.has(reference.key)) {
+          throw new InterpreterRuntimeError("Array methods cannot be assigned.", node)
+        }
+      }
       const key = reference.key
       const { write, next, result } = yield* compute(self.readReferenceValue(reference, key))
       if (write) self.assignToReference(reference, key, next, node)
@@ -2255,10 +2242,23 @@ class Frame<R> {
       return Reflect.get(reference.target.url, key)
     }
     if (reference.target instanceof Values.RegExp) return reference.target.lastIndex
-    return get(reference.target, key)
+    return Reflect.get(reference.target, key)
   }
 
   private assignToReference(reference: MemberReference, key: PropertyKey, next: unknown, node: AstNode): void {
+    if (Array.isArray(reference.target)) {
+      const target = reference.target
+      if (typeof key !== "number" || parseArrayIndex(key) === undefined) {
+        throw new InterpreterRuntimeError(
+          "Array assignment index must be a valid array index.",
+          node,
+          "InvalidDataValue",
+        )
+      }
+      rejectCircularInsertion(target, next, "Array assignment result", node)
+      target[key] = next
+      return
+    }
     if (reference.target instanceof Values.URL) {
       const property = key as string
       if (!urlWritableProperties.has(property)) {
@@ -2277,16 +2277,9 @@ class Frame<R> {
       reference.target.lastIndex = next
       return
     }
-    const target = reference.target
-    rejectCircularInsertion(
-      target,
-      next,
-      target instanceof ProgramArray ? "Array assignment result" : "Object assignment result",
-      node,
-    )
-    if (set(target, key, next)) return
-    if (target instanceof ProgramArray) throw new InterpreterRuntimeError("Invalid array length", node).as("RangeError")
-    throw new InterpreterRuntimeError(`Cannot assign to read only property '${String(key)}'.`, node).as("TypeError")
+    const target = reference.target as SafeObject
+    rejectCircularInsertion(target, next, "Object assignment result", node)
+    Reflect.set(target, key, next)
   }
 
   private toPropertyKey(value: unknown, node: AstNode): PropertyKey {

packages/codemode/src/stdlib/array.ts

@@ -1,27 +1,28 @@
 import { Effect } from "effect"
 import { HostFunction, sync, syncCall } from "../interpreter/host.js"
 import { type AstNode, CodeModeGenerator, InterpreterRuntimeError } from "../interpreter/model.js"
-import { get, ProgramArray, ProgramObject } from "../interpreter/objects.js"
 import { describeValue } from "../interpreter/references.js"
 import { applyCollectionCallback, preserveConsumerError, type Runner } from "../interpreter/runner.js"
 
-const constructArray = (args: Array<unknown>, node: AstNode): ProgramArray => {
-  if (args.length !== 1) return new ProgramArray([...args])
+const constructArray = (args: Array<unknown>, node: AstNode): Array<unknown> => {
+  if (args.length !== 1) return [...args]
   const first = args[0]
-  if (typeof first !== "number") return new ProgramArray([first])
+  if (typeof first !== "number") return [first]
   if (!Number.isInteger(first) || first < 0 || first > 4294967295) {
     throw new InterpreterRuntimeError("Invalid array length.", node).as("RangeError")
   }
   // Sparse like JS: Array(3) has holes, and combinator loops already skip them.
-  return new ProgramArray(new Array(first))
+  return new Array(first)
 }
 
-const arrayLikeSource = (
-  source: unknown,
-  node: AstNode,
-): { readonly length: number; readonly source: ProgramObject } => {
-  if (source instanceof ProgramObject && typeof get(source, "length") === "number") {
-    const length = get(source, "length") as number
+const arrayLikeSource = (source: unknown, node: AstNode): { readonly length: number; readonly source: object } => {
+  if (
+    source !== null &&
+    typeof source === "object" &&
+    (Object.getPrototypeOf(source) === Object.prototype || Object.getPrototypeOf(source) === null) &&
+    typeof (source as { length?: unknown }).length === "number"
+  ) {
+    const length = (source as { length: number }).length
     const normalized = Number.isNaN(length) || length <= 0 ? 0 : Math.trunc(length)
     if (normalized > 4_294_967_295) throw new RangeError("Invalid array length")
     return { length: normalized, source }
@@ -48,16 +49,16 @@ const arrayFrom = <R>(runner: Runner<R>, args: Array<unknown>, node: AstNode): E
       const arrayLike = arrayLikeSource(source, node)
       const values: Array<unknown> = []
       for (let index = 0; index < arrayLike.length; index += 1) {
-        const item = get(arrayLike.source, index)
+        const item = Reflect.get(arrayLike.source, index)
         values.push(apply === undefined ? item : yield* apply([item, index]))
       }
-      return new ProgramArray(values)
+      return values
     }
     const values: Array<unknown> = []
     let index = 0
     while (true) {
       const step = yield* cursor.next
-      if (step.done) return new ProgramArray(values)
+      if (step.done) return values
       values.push(apply === undefined ? step.value : yield* preserveConsumerError(cursor, apply([step.value, index])))
       index += 1
     }
@@ -70,10 +71,10 @@ export const arrayGlobal = <R>(runner: Runner<R>) =>
     name: "Array",
     call: syncCall(constructArray),
     construct: syncCall(constructArray),
-    instanceOf: (value) => value instanceof ProgramArray,
+    instanceOf: (value) => Array.isArray(value),
     members: {
-      isArray: sync("Array.isArray", (args) => args[0] instanceof ProgramArray),
-      of: sync("Array.of", (args) => new ProgramArray([...args])),
+      isArray: sync("Array.isArray", (args) => Array.isArray(args[0])),
+      of: sync("Array.of", (args) => [...args]),
       from: new HostFunction<R>({ name: "Array.from", call: (args, node) => arrayFrom(runner, args, node) }),
     },
   })

packages/codemode/src/stdlib/collections.ts

@@ -1,7 +1,7 @@
 import { Effect } from "effect"
+import type { SafeObject } from "../data.js"
 import { HostFunction, requiresNew } from "../interpreter/host.js"
-import { type AstNode, InterpreterRuntimeError } from "../interpreter/model.js"
-import { getOwn, ProgramArray, ProgramObject, set } from "../interpreter/objects.js"
+import { type AstNode, InterpreterRuntimeError, isRecord } from "../interpreter/model.js"
 import { describeValue, isRuntimeReference } from "../interpreter/references.js"
 import { applyCollectionCallback, preserveConsumerError, type Runner, toPrimitive } from "../interpreter/runner.js"
 import { Values } from "../values.js"
@@ -108,13 +108,13 @@ export const groupBy = <R>(runner: Runner<R>, namespace: "Map" | "Object") =>
             const item = step.value
             const key = yield* preserveConsumerError(cursor, apply([item, index]))
             const group = result.map.get(key)
-            if (group === undefined) result.map.set(key, new ProgramArray([item]))
-            else (group as ProgramArray).items.push(item)
+            if (group === undefined) result.map.set(key, [item])
+            else (group as Array<unknown>).push(item)
             index += 1
           }
         }
 
-        const result = new ProgramObject()
+        const result: SafeObject = Object.create(null) as SafeObject
         let index = 0
         while (true) {
           const step = yield* cursor.next
@@ -124,9 +124,9 @@ export const groupBy = <R>(runner: Runner<R>, namespace: "Map" | "Object") =>
             cursor,
             Effect.flatMap(apply([item, index]), (value) => coerceGroupByPropertyKey(runner, value, node)),
           )
-          const group = getOwn(result, key)
-          if (group === undefined) set(result, key, new ProgramArray([item]))
-          else (group as ProgramArray).items.push(item)
+          const group = result[key]
+          if (group === undefined) result[key] = [item]
+          else (group as Array<unknown>).push(item)
           index += 1
         }
       })
@@ -150,12 +150,12 @@ const constructMap = <R>(runner: Runner<R>, init: unknown, node: AstNode) => {
       yield* preserveConsumerError(
         cursor,
         Effect.sync(() => {
-          if (!(step.value instanceof ProgramObject)) {
+          if (!isRecord(step.value) || isRuntimeReference(step.value)) {
             throw new InterpreterRuntimeError("new Map(...) expects [key, value] pairs as entry objects.", node).as(
               "TypeError",
             )
           }
-          target.map.set(getOwn(step.value, 0), getOwn(step.value, 1))
+          target.map.set(step.value[0], step.value[1])
         }),
       )
     }

packages/codemode/src/stdlib/console.ts

@@ -1,6 +1,5 @@
 import { toData, toProgram } from "../data.js"
 import { HostNamespace, sync } from "../interpreter/host.js"
-import { get, ownEntries, ProgramArray, ProgramObject } from "../interpreter/objects.js"
 import { containsOpaqueReference, containsRuntimeReference, isRuntimeReference } from "../interpreter/references.js"
 import { Values } from "../values.js"
 import { coerceToString } from "./value.js"
@@ -52,8 +51,8 @@ const formatConsoleValue = (value: unknown, seen: Set<object>, depth: number): s
   if (value instanceof Values.Map) {
     seen.add(value)
     try {
-      const entries = Array.from(value.map.entries(), ([key, item]) => new ProgramArray([key, item]))
-      return `Map(${value.map.size}) ${formatConsoleValue(new ProgramArray(entries), seen, depth + 1)}`
+      const entries = Array.from(value.map.entries(), ([key, item]): Array<unknown> => [key, item])
+      return `Map(${value.map.size}) ${formatConsoleValue(entries, seen, depth + 1)}`
     } finally {
       seen.delete(value)
     }
@@ -61,7 +60,7 @@ const formatConsoleValue = (value: unknown, seen: Set<object>, depth: number): s
   if (value instanceof Values.Set) {
     seen.add(value)
     try {
-      return `Set(${value.set.size}) ${formatConsoleValue(new ProgramArray([...value.set.values()]), seen, depth + 1)}`
+      return `Set(${value.set.size}) ${formatConsoleValue(Array.from(value.set.values()), seen, depth + 1)}`
     } finally {
       seen.delete(value)
     }
@@ -69,11 +68,10 @@ const formatConsoleValue = (value: unknown, seen: Set<object>, depth: number): s
   if (isRuntimeReference(value)) return "[opaque reference]"
   seen.add(value)
   try {
-    if (value instanceof ProgramArray) {
-      return `[${value.items.map((item) => formatConsoleValue(item, seen, depth + 1)).join(",")}]`
+    if (Array.isArray(value)) {
+      return `[${value.map((item) => formatConsoleValue(item, seen, depth + 1)).join(",")}]`
     }
-    if (!(value instanceof ProgramObject)) return "[object Object]"
-    return `{${ownEntries(value)
+    return `{${Object.entries(value)
       .map(([key, item]) => `${JSON.stringify(key)}:${formatConsoleValue(item, seen, depth + 1)}`)
       .join(",")}}`
   } finally {
@@ -106,19 +104,20 @@ const consoleTableRows = (
   data: unknown,
   columns: ReadonlyArray<string> | undefined,
 ): Array<{ readonly index: string; readonly values: Record<string, unknown> }> => {
-  if (data instanceof ProgramArray) {
-    return data.items.map((item, index) => ({ index: String(index), values: consoleTableValues(item, columns) }))
+  if (Array.isArray(data)) {
+    return data.map((item, index) => ({ index: String(index), values: consoleTableValues(item, columns) }))
   }
-  if (data instanceof ProgramObject) {
-    return ownEntries(data).map(([index, item]) => ({ index, values: consoleTableValues(item, columns) }))
+  if (data !== null && typeof data === "object" && !Values.isValue(data)) {
+    return Object.entries(data).map(([index, item]) => ({ index, values: consoleTableValues(item, columns) }))
   }
   return [{ index: "0", values: { Value: data } }]
 }
 
 const consoleTableValues = (value: unknown, columns: ReadonlyArray<string> | undefined): Record<string, unknown> => {
-  if (value instanceof ProgramObject && !(value instanceof ProgramArray)) {
-    if (columns !== undefined) return Object.fromEntries(columns.map((column) => [column, get(value, column)]))
-    return Object.fromEntries(ownEntries(value))
+  if (value !== null && typeof value === "object" && !Array.isArray(value) && !Values.isValue(value)) {
+    const source = value as Record<string, unknown>
+    if (columns !== undefined) return Object.fromEntries(columns.map((column) => [column, source[column]]))
+    return Object.fromEntries(Object.entries(source))
   }
   return { Value: value }
 }

packages/codemode/src/stdlib/json.ts

@@ -3,8 +3,7 @@ import { HostFunction, HostNamespace } from "../interpreter/host.js"
 import { applyCollectionCallback, type Runner } from "../interpreter/runner.js"
 import { type AstNode, InterpreterRuntimeError } from "../interpreter/model.js"
 import { typeofValue } from "../interpreter/references.js"
-import { fromData, toData, toProgram } from "../data.js"
-import { get, ownKeys, ProgramArray, ProgramObject, record, remove, set } from "../interpreter/objects.js"
+import { fromData, type SafeObject, toData, toProgram } from "../data.js"
 import { Values } from "../values.js"
 
 export const jsonGlobal = <R>(runner: Runner<R>) =>
@@ -30,19 +29,28 @@ const parse = <R>(runner: Runner<R>, args: Array<unknown>, node: AstNode): Effec
   if (typeofValue(args[1]) !== "function") return Effect.succeed(parsed)
 
   const apply = applyCollectionCallback(runner, args[1], "JSON.parse", node)
-  const visit = (holder: ProgramObject, key: string): Effect.Effect<unknown, unknown, R> =>
+  const root: SafeObject = Object.create(null) as SafeObject
+  root[""] = parsed
+  const visit = (holder: SafeObject | Array<unknown>, key: string): Effect.Effect<unknown, unknown, R> =>
     Effect.gen(function* () {
-      const value = get(holder, key)
-      if (value instanceof ProgramObject) {
-        for (const name of ownKeys(value)) {
-          const revived = yield* visit(value, name as string)
-          if (revived === undefined) remove(value, name)
-          else set(value, name, revived)
+      const value = holder[key as keyof typeof holder]
+      if (Array.isArray(value)) {
+        const length = value.length
+        for (let index = 0; index < length; index += 1) {
+          const revived = yield* visit(value, String(index))
+          if (revived === undefined) Reflect.deleteProperty(value, index)
+          else value[index] = revived
+        }
+      } else if (isPlainObject(value)) {
+        for (const name of Object.keys(value)) {
+          const revived = yield* visit(value, name)
+          if (revived === undefined) Reflect.deleteProperty(value, name)
+          else value[name] = revived
         }
       }
       return yield* apply([key, value])
     })
-  return visit(record({ "": parsed }), "")
+  return visit(root, "")
 }
 
 const stringify = <R>(runner: Runner<R>, args: Array<unknown>, node: AstNode): Effect.Effect<unknown, unknown, R> => {
@@ -51,41 +59,44 @@ const stringify = <R>(runner: Runner<R>, args: Array<unknown>, node: AstNode): E
   const replacer = args[1]
 
   if (typeofValue(replacer) !== "function") {
-    const properties =
-      replacer instanceof ProgramArray
-        ? replacer.items
-            .filter((item): item is string | number => typeof item === "string" || typeof item === "number")
-            .map(String)
-        : null
+    const properties = Array.isArray(replacer)
+      ? replacer
+          .filter((item): item is string | number => typeof item === "string" || typeof item === "number")
+          .map(String)
+      : null
     return Effect.succeed(JSON.stringify(toData(args[0], "JSON.stringify value"), properties, indent))
   }
 
   // Validate up front; the replacer walk below reads the original value.
   toProgram(args[0], "JSON.stringify value")
   const apply = applyCollectionCallback(runner, replacer, "JSON.stringify", node)
+  const root: SafeObject = Object.create(null) as SafeObject
+  root[""] = args[0]
   const stack = new Set<object>()
-  const visit = (holder: ProgramObject, key: string): Effect.Effect<unknown, unknown, R> =>
+  const visit = (holder: SafeObject | Array<unknown>, key: string): Effect.Effect<unknown, unknown, R> =>
     Effect.gen(function* () {
-      const value = yield* apply([key, toJSONValue(get(holder, key))])
+      const value = yield* apply([key, toJSONValue(holder[key as keyof typeof holder])])
       if (value === undefined || typeofValue(value) === "function") return undefined
       toProgram(value, "JSON.stringify replacer result")
       if (typeof value === "number") return Number.isFinite(value) ? value : null
       if (value === null || typeof value === "string" || typeof value === "boolean") return value
-      if (!(value instanceof ProgramObject)) return {}
-      if (stack.has(value))
-        throw new InterpreterRuntimeError("Converting circular structure to JSON.", node).as("TypeError")
-      stack.add(value)
-      if (value instanceof ProgramArray) {
+      if (Array.isArray(value)) {
+        if (stack.has(value))
+          throw new InterpreterRuntimeError("Converting circular structure to JSON.", node).as("TypeError")
+        stack.add(value)
         const result: Array<unknown> = []
-        for (let index = 0; index < value.items.length; index += 1) {
+        for (let index = 0; index < value.length; index += 1) {
           result.push((yield* visit(value, String(index))) ?? null)
         }
         stack.delete(value)
         return result
       }
-      const result: Record<string, unknown> = Object.create(null)
-      for (const name of ownKeys(value)) {
-        if (typeof name !== "string") continue
+      if (!isPlainObject(value)) return {}
+      if (stack.has(value))
+        throw new InterpreterRuntimeError("Converting circular structure to JSON.", node).as("TypeError")
+      stack.add(value)
+      const result: SafeObject = Object.create(null) as SafeObject
+      for (const name of Object.keys(value)) {
         const item = yield* visit(value, name)
         if (item !== undefined) result[name] = item
       }
@@ -93,7 +104,7 @@ const stringify = <R>(runner: Runner<R>, args: Array<unknown>, node: AstNode): E
       return result
     })
 
-  return Effect.map(visit(record({ "": args[0] }), ""), (value) => JSON.stringify(value, null, indent))
+  return Effect.map(visit(root, ""), (value) => JSON.stringify(value, null, indent))
 }
 
 const toJSONValue = (value: unknown): unknown => {
@@ -103,3 +114,6 @@ const toJSONValue = (value: unknown): unknown => {
   if (value instanceof Values.URL) return value.url.href
   return value
 }
+
+const isPlainObject = (value: unknown): value is SafeObject =>
+  value !== null && typeof value === "object" && !Values.isValue(value)

packages/codemode/src/stdlib/object.ts

@@ -2,10 +2,11 @@ import { Effect } from "effect"
 import { toProgram } from "../data.js"
 import { HostFunction, sync, syncCall } from "../interpreter/host.js"
 import { type AstNode, AsyncIteratorSymbol, InterpreterRuntimeError, IteratorSymbol } from "../interpreter/model.js"
-import { getOwn, hasOwn, ownEntries, ownKeys, ProgramArray, ProgramObject, set } from "../interpreter/objects.js"
 import {
   containsOpaqueReference,
   describeValue,
+  isRuntimeReference,
+  parseArrayIndex,
   rejectCircularInsertion,
   typeofValue,
 } from "../interpreter/references.js"
@@ -15,8 +16,9 @@ import { Values } from "../values.js"
 import { groupBy } from "./collections.js"
 import { coerceToString } from "./value.js"
 
-// ToObject for enumeration.
-export const enumerableSource = (label: string, value: unknown, node: AstNode): ProgramObject => {
+// ToObject for enumeration. Strings return themselves: the host's Object.keys/entries/hasOwn index a
+// primitive string directly. Numbers, booleans, wrappers, and functions have no own enumerable keys.
+export const enumerableSource = (label: string, value: unknown, node: AstNode): Record<string, unknown> => {
   if (value === null || value === undefined) {
     throw new InterpreterRuntimeError(`${label} cannot convert ${describeValue(value)} to an object.`, node).as(
       "TypeError",
@@ -36,41 +38,58 @@ export const enumerableSource = (label: string, value: unknown, node: AstNode):
       "InvalidDataValue",
     )
   }
-  if (typeof value === "string") return new ProgramArray([...value])
-  if (value instanceof ProgramObject) return value
-  return new ProgramObject()
+  if (typeof value === "string") return value as unknown as Record<string, unknown>
+  if (typeof value !== "object" || Values.isValue(value) || isRuntimeReference(value)) return {}
+  return value as Record<string, unknown>
 }
 
 export const objectAssign = (args: Array<unknown>, node: AstNode): unknown => {
   const target = args[0]
   // JS would box a primitive target; wrappers and primitives cannot hold fields here.
-  if (!(target instanceof ProgramObject)) {
+  if (target === null || typeof target !== "object" || Values.isValue(target) || isRuntimeReference(target)) {
     throw new InterpreterRuntimeError(
       `Object.assign expects a data object or array target, received ${describeValue(target)}.`,
       node,
     ).as("TypeError")
   }
+  const out = target as Record<string, unknown>
   const seen = new Set<object>()
+  const guardedSet = (key: PropertyKey, item: unknown): void => {
+    // Arrays hold only indexed elements, as with direct assignment; Reflect.set would otherwise
+    // reach Array's length and Object.prototype's __proto__ setter.
+    if (Array.isArray(out) && (typeof key === "symbol" || parseArrayIndex(key) === undefined)) {
+      throw new InterpreterRuntimeError(
+        `Object.assign cannot assign '${String(key)}' to an array: only array indexes may be assigned.`,
+        node,
+      ).as("TypeError")
+    }
+    rejectCircularInsertion(out, item, "Object.assign result", node, seen)
+    if (!Reflect.set(out, key, item))
+      throw new InterpreterRuntimeError(`Object.assign could not assign property '${String(key)}'.`, node).as(
+        "TypeError",
+      )
+  }
   for (const source of args.slice(1)) {
     if (source === null || source === undefined) continue
     const from = enumerableSource("Object.assign(...)", source, node)
-    for (const key of ownKeys(from)) {
+    if (typeof from !== "object") {
+      for (const [key, item] of Object.entries(from)) guardedSet(key, item)
+      continue
+    }
+    for (const key of Reflect.ownKeys(from)) {
       if (typeof key === "symbol" && key !== AsyncIteratorSymbol && key !== IteratorSymbol) continue
-      rejectCircularInsertion(target, getOwn(from, key), "Object.assign result", node, seen)
-      if (!set(target, key, getOwn(from, key))) {
-        throw new InterpreterRuntimeError("Invalid array length", node).as("RangeError")
-      }
+      if (Object.prototype.propertyIsEnumerable.call(from, key)) guardedSet(key, Reflect.get(from, key))
     }
   }
-  return target
+  return out
 }
 
 const objectFromEntries = <R>(
   runner: Runner<R>,
   source: unknown,
   node: AstNode,
-): Effect.Effect<ProgramObject, unknown, R> => {
-  const out = new ProgramObject()
+): Effect.Effect<Record<string, unknown>, unknown, R> => {
+  const out: Record<string, unknown> = Object.create(null)
   return Effect.gen(function* () {
     const cursor = yield* runner.syncIterator(source, node)
     if (cursor === undefined) {
@@ -84,12 +103,21 @@ const objectFromEntries = <R>(
       yield* preserveConsumerError(
         cursor,
         Effect.sync(() => {
-          if (!(step.value instanceof ProgramObject) || containsOpaqueReference(step.value)) {
+          if (
+            step.value === null ||
+            typeof step.value !== "object" ||
+            Values.isValue(step.value) ||
+            containsOpaqueReference(step.value)
+          ) {
             throw new InterpreterRuntimeError("Object.fromEntries expects [key, value] entry objects.", node).as(
               "TypeError",
             )
           }
-          set(out, coerceToString(getOwn(step.value, 0)), getOwn(step.value, 1))
+          const entry = step.value as Record<string, unknown>
+          toProgram(entry[0], "Object.fromEntries key")
+          toProgram(entry[1], "Object.fromEntries value")
+          const key = coerceToString(entry[0])
+          out[key] = entry[1]
         }),
       )
     }
@@ -98,7 +126,7 @@ const objectFromEntries = <R>(
 
 const constructObject = (args: Array<unknown>, node: AstNode): unknown => {
   const first = args[0]
-  if (first === null || first === undefined) return new ProgramObject()
+  if (first === null || first === undefined) return Object.create(null)
   if (typeof first === "object") return first
   throw new InterpreterRuntimeError(
     `Object(${typeof first}) wrapper objects are not supported; use the primitive value directly.`,
@@ -119,24 +147,18 @@ export const objectGlobal = <R>(runner: Runner<R>, toolKeys: (path: ReadonlyArra
         toProgram(
           args[0] instanceof ToolReference
             ? [...toolKeys(args[0].path)]
-            : ownKeys(enumerableSource("Object.keys(...)", args[0], node)).filter((key) => typeof key === "string"),
+            : Object.keys(enumerableSource("Object.keys(...)", args[0], node)),
           "Object.keys result",
         ),
       ),
-      values: sync(
-        "Object.values",
-        (args, node) =>
-          new ProgramArray(ownEntries(enumerableSource("Object.values(...)", args[0], node)).map((entry) => entry[1])),
+      values: sync("Object.values", (args, node) =>
+        Object.values(enumerableSource("Object.values(...)", args[0], node)),
       ),
-      entries: sync(
-        "Object.entries",
-        (args, node) =>
-          new ProgramArray(
-            ownEntries(enumerableSource("Object.entries(...)", args[0], node)).map((entry) => new ProgramArray(entry)),
-          ),
+      entries: sync("Object.entries", (args, node) =>
+        Object.entries(enumerableSource("Object.entries(...)", args[0], node)).map(([key, item]) => [key, item]),
       ),
       hasOwn: sync("Object.hasOwn", (args, node) =>
-        hasOwn(
+        Object.hasOwn(
           enumerableSource("Object.hasOwn(...)", args[0], node),
           args[1] === AsyncIteratorSymbol || args[1] === IteratorSymbol ? args[1] : String(args[1]),
         ),

packages/codemode/src/stdlib/regexp.ts

@@ -1,9 +1,19 @@
 import { sync, syncCall } from "../interpreter/host.js"
 import { type AstNode, InterpreterRuntimeError } from "../interpreter/model.js"
-import { ProgramArray, record, set } from "../interpreter/objects.js"
+import type { SafeObject } from "../data.js"
 import { Values } from "../values.js"
 import { coerceToNumber, coerceToString } from "./value.js"
 
+type MatchValue = Array<unknown> & {
+  index?: number
+  groups?: SafeObject
+  indices?: IndicesValue
+}
+
+type IndicesValue = Array<unknown> & {
+  groups?: SafeObject
+}
+
 export const regexpMethods = new Set(["test", "exec", "toString"])
 
 export const regexpProperties = new Set([
@@ -46,12 +56,17 @@ export const toHostRegex = (arg: unknown, method: string, node: AstNode, extraFl
   )
 }
 
-export const matchToValue = (match: RegExpMatchArray): ProgramArray => {
-  const result = new ProgramArray(Array.from(match, (group) => group))
-  if (match.index !== undefined) set(result, "index", match.index)
-  if (match.input !== undefined) set(result, "input", match.input)
-  if (match.groups) set(result, "groups", record(match.groups))
-  if (match.indices) set(result, "indices", indicesToValue(match.indices))
+export const matchToValue = (match: RegExpMatchArray): Array<unknown> => {
+  const result: MatchValue = Array.from(match, (group) => group)
+  if (match.index !== undefined) result.index = match.index
+  if (match.groups) {
+    const groups: SafeObject = Object.create(null) as SafeObject
+    for (const [key, group] of Object.entries(match.groups)) {
+      groups[key] = group
+    }
+    result.groups = groups
+  }
+  if (match.indices) result.indices = indicesToValue(match.indices)
   return result
 }
 
@@ -128,16 +143,16 @@ const toLength = (value: unknown): number => {
   return Math.min(Math.floor(number), Number.MAX_SAFE_INTEGER)
 }
 
-const indicesToValue = (indices: RegExpIndicesArray): ProgramArray => {
-  const range = (pair: [number, number] | undefined) => (pair === undefined ? undefined : new ProgramArray([...pair]))
-  const result = new ProgramArray(Array.from(indices, range))
-  const groups = indices.groups
-  set(
-    result,
-    "groups",
-    groups === undefined
-      ? undefined
-      : record(Object.fromEntries(Object.entries(groups).map(([key, pair]) => [key, range(pair)]))),
-  )
+const indicesToValue = (indices: RegExpIndicesArray): IndicesValue => {
+  const result: IndicesValue = Array.from(indices, (range) => (range === undefined ? undefined : [...range]))
+  if (indices.groups) {
+    const groups: SafeObject = Object.create(null) as SafeObject
+    for (const [key, range] of Object.entries(indices.groups)) {
+      groups[key] = range === undefined ? undefined : [...range]
+    }
+    result.groups = groups
+    return result
+  }
+  result.groups = undefined
   return result
 }

packages/codemode/src/stdlib/url.ts

@@ -2,7 +2,6 @@ import { Effect } from "effect"
 import { toProgram } from "../data.js"
 import { HostFunction, requiresNew, sync, syncCall } from "../interpreter/host.js"
 import { type AstNode, InterpreterRuntimeError } from "../interpreter/model.js"
-import { ownEntries, ProgramObject } from "../interpreter/objects.js"
 import { isRuntimeReference } from "../interpreter/references.js"
 import { preserveConsumerError, type Runner } from "../interpreter/runner.js"
 import { Values } from "../values.js"
@@ -184,14 +183,15 @@ const constructURLSearchParams = <R>(
       ).as("TypeError")
     }
     if (Values.isValue(init)) return new Values.URLSearchParams(new URLSearchParams())
-    if (!(init instanceof ProgramObject)) {
+    const data = toProgram(init, "new URLSearchParams input")
+    if (data === null || typeof data !== "object") {
       throw new InterpreterRuntimeError(
         "new URLSearchParams(...) expects a query string, data object, iterable pairs, or URLSearchParams.",
         node,
       ).as("TypeError")
     }
     return new Values.URLSearchParams(
-      new URLSearchParams(Object.fromEntries(ownEntries(init).map(([key, value]) => [key, coerceToString(value)]))),
+      new URLSearchParams(Object.fromEntries(Object.entries(data).map(([key, value]) => [key, coerceToString(value)]))),
     )
   })
 }

packages/codemode/src/stdlib/value.ts

@@ -1,7 +1,6 @@
 import { type HostFunction, sync, type SyncOptions } from "../interpreter/host.js"
 import { type AstNode, InterpreterRuntimeError } from "../interpreter/model.js"
-import { toProgram } from "../data.js"
-import { get, ProgramArray, ProgramError, set } from "../interpreter/objects.js"
+import { type SafeObject, toProgram } from "../data.js"
 import { Values } from "../values.js"
 
 export const errorConstructors = new Set([
@@ -17,21 +16,21 @@ export const errorConstructors = new Set([
 
 export const compoundOperators = new Set(["+=", "-=", "*=", "/=", "%=", "**=", "&=", "|=", "^=", "<<=", ">>=", ">>>="])
 
-export const createErrorValue = (name: string, message: string): ProgramError => {
-  const value = new ProgramError(name)
-  set(value, "name", name)
-  set(value, "message", message)
+const ErrorBrand: unique symbol = Symbol("codemode.error")
+
+export const createErrorValue = (name: string, message: string): SafeObject => {
+  const value = Object.assign(Object.create(null) as SafeObject, { name, message })
+  Object.defineProperty(value, ErrorBrand, { value: name })
   return value
 }
 
-export const createAggregateErrorValue = (errors: Array<unknown>, message: string): ProgramError => {
-  const value = createErrorValue("AggregateError", message)
-  set(value, "errors", new ProgramArray(errors))
-  return value
-}
+export const createAggregateErrorValue = (errors: Array<unknown>, message: string): SafeObject =>
+  Object.assign(createErrorValue("AggregateError", message), { errors })
 
 export const errorBrandName = (value: unknown): string | undefined =>
-  value instanceof ProgramError ? value.errorName : undefined
+  value !== null && typeof value === "object"
+    ? ((value as Record<PropertyKey, unknown>)[ErrorBrand] as string | undefined)
+    : undefined
 
 export const coerceToString = (value: unknown): string => {
   if (value === null) return "null"
@@ -43,27 +42,29 @@ export const coerceToString = (value: unknown): string => {
   if (value instanceof Values.Set) return "[object Set]"
   if (value instanceof Values.URL) return value.url.href
   if (value instanceof Values.URLSearchParams) return value.params.toString()
-  if (value instanceof ProgramError) {
+  if (errorBrandName(value) !== undefined) {
     // Match Error.prototype.toString: "name: message", or just one when the other is empty.
-    const name = get(value, "name")
-    const message = get(value, "message")
-    const shownName = typeof name === "string" ? name : "Error"
-    const shownMessage = typeof message === "string" ? message : ""
-    if (shownMessage === "") return shownName
-    if (shownName === "") return shownMessage
-    return `${shownName}: ${shownMessage}`
+    const error = value as { name?: unknown; message?: unknown }
+    const name = typeof error.name === "string" ? error.name : "Error"
+    const message = typeof error.message === "string" ? error.message : ""
+    if (message === "") return name
+    if (name === "") return message
+    return `${name}: ${message}`
   }
-  if (value instanceof ProgramArray) {
-    return value.items.map((item) => (item === null || item === undefined ? "" : coerceToString(item))).join(",")
+  if (typeof value === "object") {
+    return Array.isArray(value)
+      ? value.map((item) => (item === null || item === undefined ? "" : coerceToString(item))).join(",")
+      : "[object Object]"
   }
-  if (typeof value === "object") return "[object Object]"
   return String(value)
 }
 
 export const coerceToNumber = (value: unknown): number => {
   if (value instanceof Values.Date) return value.time
   if (Values.isValue(value)) return Number.NaN
-  if (value instanceof ProgramArray) return Number(coerceToString(value))
+  // Arrays coerce through our own string coercion: host Number(array) joins with host
+  // ToPrimitive, which throws on the null-prototype objects the interpreter produces.
+  if (Array.isArray(value)) return Number(coerceToString(value))
   return value !== null && typeof value === "object" ? Number.NaN : Number(value)
 }
 
@@ -77,6 +78,8 @@ const coerce = (name: Coercion, args: Array<unknown>, node: AstNode): unknown =>
     if (name === "String") return ""
   }
   const raw = args[0]
+  // Error values are plain SafeObjects; the toProgram path below would strip their brand.
+  if (name === "String" && errorBrandName(raw) !== undefined) return coerceToString(raw)
   if (Values.isValue(raw)) {
     if (name === "Boolean") return true
     if (name === "Number") return coerceToNumber(raw)