refactor(rpc): remove redundant machinery

Separate ID-bound Session policy from host routing. Bind Inbox and Location preparation dependencies at construction, preserve admission and execution semantics, and cover the extracted ownership contracts directly.

.changeset/directory-page-heading.md

@@ -0,0 +1,5 @@
+---
+"@opencode-ai/core": patch
+---
+
+Correct directory page headings when the read offset is zero.

.gitattributes

@@ -2,3 +2,4 @@ packages/core/migration/**/snapshot.json linguist-generated
 packages/core/src/database/migration.gen.ts linguist-generated
 packages/core/src/models-dev/snapshot.txt linguist-generated
 packages/core/src/**/*.txt text eol=lf
+packages/httpapi-codegen/test/generated/*.ts text eol=lf

.github/workflows/deploy.yml

@@ -5,6 +5,7 @@ on:
     branches:
       - dev
       - production
+      - beta
   workflow_dispatch:
 
 concurrency: ${{ github.workflow }}-${{ github.ref }}
@@ -15,7 +16,7 @@ permissions:
 
 jobs:
   deploy:
-    if: github.repository == 'anomalyco/opencode' && (github.ref_name == 'dev' || github.ref_name == 'production')
+    if: github.repository == 'anomalyco/opencode' && (github.ref_name == 'dev' || github.ref_name == 'production' || github.ref_name == 'beta')
     runs-on: ubuntu-latest
     environment: ${{ github.ref_name }}
     steps:
@@ -28,6 +29,7 @@ jobs:
           node-version: "24"
 
       - uses: aws-actions/configure-aws-credentials@7474bc4690e29a8392af63c5b98e7449536d5c3a # v4.3.1
+        if: github.ref_name != 'beta'
         with:
           role-to-assume: ${{ vars.AWS_DEPLOY_ROLE_ARN }}
           role-session-name: opencode-${{ github.run_id }}

AGENTS.md

@@ -1,6 +1,7 @@
 - After changing the public Protocol or Server `HttpApi`, run `bun run generate` from `packages/client`. Do not edit generated client files directly.
 - Keep runtime dependencies directed from Schema to Core and Protocol, then from Core and Protocol to Server. Client runtime code may depend on Schema and Protocol but never Core or Server; `sdk` composes Client, Core, and Server.
 - Current implementation changes belong in `packages/core`, `packages/cli`, `packages/server`, `packages/protocol`, `packages/schema`, and related generated client surfaces when required.
+- This repository does not use Changesets. Do not add `.changeset` files; follow the existing release workflow instead.
 - The default branch in this repo is `v2`.
 - Base all new branches and worktrees on `v2`, or `origin/v2` when the local `v2` ref is unavailable. Do not base them on `dev`.
 - Local `main` ref may not exist; use `v2` or `origin/v2` for diffs.
@@ -45,6 +46,7 @@ Examples: `fix(tui): simplify thinking toggle styling`, `docs: update contributi
 ### General Principles
 
 - Keep things in one function unless composable or reusable
+- Validate unknown values once at the boundary that owns them. Pass typed values inward instead of repeating `typeof value === "object"` and property-existence checks. Do not defensively revalidate values already guaranteed by a schema, constructor, or internal type.
 - Do not extract single-use helpers preemptively. Inline the logic at the call site unless the helper is reused, hides a genuinely complex boundary, or has a clear independent name that improves the caller.
 - Before adding complexity for a speculative or vanishingly unlikely race or security edge case, explain the concrete failure mode, likelihood, and complexity cost to the user and get their buy-in. Do not silently expand scope for theoretical robustness.
 - Avoid `try`/`catch` where possible

bun.lock

@@ -183,6 +183,7 @@
         "@typescript/native-preview": "catalog:",
         "effect": "catalog:",
         "solid-js": "catalog:",
+        "zod": "catalog:",
       },
       "peerDependencies": {
         "effect": "4.0.0-rc.112",

infra/app.ts

@@ -1,4 +1,5 @@
 import { domain } from "./stage"
+import { createWebApp } from "./webapp"
 
 const GITHUB_APP_ID = new sst.Secret("GITHUB_APP_ID")
 const GITHUB_APP_PRIVATE_KEY = new sst.Secret("GITHUB_APP_PRIVATE_KEY")
@@ -59,12 +60,4 @@ new sst.cloudflare.x.Astro("Web", {
   },
 })
 
-new sst.cloudflare.StaticSite("WebApp", {
-  domain: "app." + domain,
-  path: "packages/app",
-  build: {
-    // Preserve Sentry credentials and run source-map uploads on every deployment.
-    command: "bun run build",
-    output: "./dist",
-  },
-})
+createWebApp("app." + domain)

infra/webapp.ts

@@ -0,0 +1,18 @@
+export function createWebApp(domain: string) {
+  return new sst.cloudflare.StaticSite("WebApp", {
+    domain,
+    path: "packages/app",
+    environment:
+      $app.stage === "beta"
+        ? {
+            OPENCODE_CHANNEL: "beta",
+            VITE_SENTRY_ENVIRONMENT: "beta",
+          }
+        : undefined,
+    build: {
+      // Preserve Sentry credentials and run source-map uploads on every deployment.
+      command: "bun run build",
+      output: "./dist",
+    },
+  })
+}

nix/hashes.json

@@ -1,8 +1,8 @@
 {
   "nodeModules": {
-    "x86_64-linux": "sha256-EtUp4pHl9TyPtRrLGvk/X7kd2LuIxNxCpUwF5aLtzN4=",
-    "aarch64-linux": "sha256-m0j/pMZCguclR3/T9JmzCfi11YzmIvBFyR2bVhIO37Y=",
-    "aarch64-darwin": "sha256-nqefk68ZTUfNU15q1WkXaGsFzPNwOjCtMHpp6WrpNqM=",
-    "x86_64-darwin": "sha256-syD7hX62E4yCDV/wux1QKw4q/zZr24f99Y2mmzMJo6o="
+    "x86_64-linux": "sha256-No3mCuG2tGQauX1HUpO+rebiWh+rrpSHUCC7rtXFu1s=",
+    "aarch64-linux": "sha256-8joWv1iDkc6TejEukGBEX0wW8DPs55wJEPY7+9+HDdM=",
+    "aarch64-darwin": "sha256-4MWGFQUIP1Ae4dujztTb4G8/uDJx2wiOoypcPSUWDbw=",
+    "x86_64-darwin": "sha256-BtvnraCJmVagtA3Iv+EbWodjFG74sTd2Purqgo7Wkr4="
   }
 }

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

@@ -1,4 +1,4 @@
-import { Effect, Schema } from "effect"
+import { Effect, Option, Schema } from "effect"
 import type { Content } from "@opencode-ai/schema/tool"
 import { HttpTransport } from "../route/transport/index.js"
 import { Protocol } from "../route/protocol.js"
@@ -845,6 +845,21 @@ const onOutputTextDone = (state: ParserState, event: Event, id: string): StepRes
   return [{ ...state, lifecycle: Lifecycle.textEnd(state.lifecycle, events, id) }, events]
 }
 
+const decodeMessagePart = Schema.decodeUnknownOption(
+  Schema.Union([OpenResponsesOutputText, Schema.Struct({ type: Schema.tag("refusal"), refusal: Schema.String })]),
+)
+
+const decodeSummaryPart = Schema.decodeUnknownOption(OpenResponsesReasoningSummaryText)
+
+const decodeReasoningPart = Schema.decodeUnknownOption(
+  Schema.Struct({ type: Schema.tag("reasoning_text"), text: Schema.String }),
+)
+
+const joinReasoningText = (parts: ReadonlyArray<string | undefined>) => {
+  if (!parts.some((part) => part !== undefined && part.length > 0)) return undefined
+  return parts.filter((part) => part !== undefined).join("\n\n")
+}
+
 export const outputItemID = (state: ParserState, event: Event) =>
   event.output_index === undefined ? event.item_id : (state.outputItems[event.output_index] ?? event.item_id)
 
@@ -1065,24 +1080,33 @@ const onFunctionCallArgumentsDelta = Effect.fn("OpenResponses.onFunctionCallArgu
   return [{ ...state, lifecycle, tools: result.tools }, events] satisfies StepResult
 })
 
-const onOutputItemDone = Effect.fn("OpenResponses.onOutputItemDone")(function* (state: ParserState, event: Event) {
-  const item = event.item
+const onOutputItemDone = Effect.fn("OpenResponses.onOutputItemDone")(function* (
+  state: ParserState,
+  item: Event["item"],
+) {
   if (!item) return [state, NO_EVENTS] satisfies StepResult
 
   if (item.type === "message" && item.id !== undefined) {
+    const message = state.message?.id === item.id ? state.message : undefined
     const itemPhase = messagePhase(item.phase)
-    const phase = itemPhase === undefined && state.message?.id === item.id ? state.message.phase : itemPhase
+    const phase = itemPhase === undefined ? message?.phase : itemPhase
+    const parts: ReadonlyArray<unknown> = Array.isArray(item.content) ? item.content : []
+    const content: string[] = []
+    for (const part of parts) {
+      const decoded = Option.getOrUndefined(decodeMessagePart(part))
+      if (!decoded) continue
+      content.push(decoded.type === "output_text" ? decoded.text : decoded.refusal)
+    }
+    const text = content.length > 0 ? content.join("") : undefined
+    const metadata = providerMetadata(state, { itemId: item.id, ...(phase === undefined ? {} : { phase }) })
     const events: LLMEvent[] = []
+    const lifecycle =
+      message && text ? Lifecycle.textStart(state.lifecycle, events, item.id, metadata) : state.lifecycle
     return [
       {
         ...state,
-        lifecycle: Lifecycle.textEnd(
-          state.lifecycle,
-          events,
-          item.id,
-          providerMetadata(state, { itemId: item.id, ...(phase === undefined ? {} : { phase }) }),
-        ),
-        message: state.message?.id === item.id ? undefined : state.message,
+        lifecycle: Lifecycle.textEnd(lifecycle, events, item.id, metadata, text),
+        message: message ? undefined : state.message,
       },
       events,
     ] satisfies StepResult
@@ -1137,17 +1161,33 @@ const onOutputItemDone = Effect.fn("OpenResponses.onOutputItemDone")(function* (
   }
 
   if (isReasoningItem(item)) {
-    const events: LLMEvent[] = []
+    if (state.reasoningItems[item.id]?.open === false) return [state, NO_EVENTS] satisfies StepResult
     const metadata = reasoningMetadata(state, item)
+    const summaryParts: ReadonlyArray<unknown> = Array.isArray(item.summary) ? item.summary : []
+    const summary: Array<string | undefined> = []
+    for (const part of summaryParts) {
+      const decoded = Option.getOrUndefined(decodeSummaryPart(part))
+      // Keep missing entries so the array still matches the provider's summary indexes.
+      summary.push(decoded?.text)
+    }
+    const reasoningParts: ReadonlyArray<unknown> = Array.isArray(item.content) ? item.content : []
+    const content: string[] = []
+    for (const part of reasoningParts) {
+      const decoded = Option.getOrUndefined(decodeReasoningPart(part))
+      if (decoded) content.push(decoded.text)
+    }
+    const itemText = joinReasoningText(summary) ?? joinReasoningText(content)
+    const events: LLMEvent[] = []
     const reasoningItem = state.reasoningItems[item.id]
     if (reasoningItem) {
-      if (!reasoningItem.open) return [state, NO_EVENTS] satisfies StepResult
-      const lifecycle = Object.entries(reasoningItem.summaryParts)
-        .filter((entry) => entry[1] === "active" || entry[1] === "can-conclude")
-        .reduce(
-          (lifecycle, entry) => Lifecycle.reasoningEnd(lifecycle, events, `${item.id}:${entry[0]}`, metadata),
-          state.lifecycle,
-        )
+      const fragments = Object.entries(reasoningItem.summaryParts)
+      let lifecycle = state.lifecycle
+      for (const [index, status] of fragments) {
+        if (status === "concluded") continue
+        // Do not repeat earlier summaries that were already emitted as separate fragments.
+        const finalText = fragments.length === 1 ? itemText : summary[Number(index)]
+        lifecycle = Lifecycle.reasoningEnd(lifecycle, events, `${item.id}:${index}`, metadata, finalText || undefined)
+      }
       return [
         {
           ...state,
@@ -1167,7 +1207,13 @@ const onOutputItemDone = Effect.fn("OpenResponses.onOutputItemDone")(function* (
     if (!state.lifecycle.reasoning.has(item.id)) {
       const lifecycle = Lifecycle.stepStart(state.lifecycle, events)
       events.push(LLMEvent.reasoningStart({ id: item.id, providerMetadata: metadata }))
-      events.push(LLMEvent.reasoningEnd({ id: item.id, providerMetadata: metadata }))
+      events.push(
+        LLMEvent.reasoningEnd({
+          id: item.id,
+          providerMetadata: metadata,
+          text: itemText,
+        }),
+      )
       return [
         {
           ...state,
@@ -1195,32 +1241,24 @@ const onOutputItemDone = Effect.fn("OpenResponses.onOutputItemDone")(function* (
 })
 
 const onResponseFinish = Effect.fn("OpenResponses.onResponseFinish")(function* (state: ParserState, event: Event) {
-  const reconciled =
-    event.type === "response.completed"
-      ? yield* Effect.reduce(
-          event.response?.output ?? [],
-          () => [state, NO_EVENTS] satisfies StepResult,
-          ([current, events], item) => {
-            const id = item.id ?? (item.type === "function_call" ? item.call_id : undefined)
-            if (
-              id === undefined ||
-              ((item.type !== "function_call" || !current.tools[id]) &&
-                (item.type !== "reasoning" || !current.reasoningItems[id]?.open))
-            )
-              return Effect.succeed([current, events] satisfies StepResult)
-            return onOutputItemDone(current, { type: "response.output_item.done", item }).pipe(
-              Effect.map(([next, emitted]) => [next, [...events, ...emitted]] satisfies StepResult),
-            )
-          },
-        )
-      : ([state, NO_EVENTS] satisfies StepResult)
-  const current = reconciled[0]
+  let current = state
+  const events: LLMEvent[] = []
+  if (event.type === "response.completed") {
+    for (const item of event.response?.output ?? []) {
+      const id = item.id ?? (item.type === "function_call" ? item.call_id : undefined)
+      if (id === undefined) continue
+      if (item.type !== "function_call" || !current.tools[id]) continue
+      const [next, emitted] = yield* onOutputItemDone(current, item)
+      current = next
+      events.push(...emitted)
+    }
+  }
   // Some compatible providers omit output_item.done even after completing the response.
   const pending =
     event.type === "response.completed"
       ? yield* ToolStream.finishAll(current.id, current.tools)
       : { tools: current.tools, events: NO_EVENTS }
-  const events: LLMEvent[] = [...reconciled[1], ...pending.events]
+  events.push(...pending.events)
   const hasFunctionCall =
     pending.events.some((event) => LLMEvent.is.toolCall(event) || LLMEvent.is.toolInputError(event)) ||
     current.hasFunctionCall
@@ -1346,7 +1384,7 @@ export const step = (state: ParserState, input: Event) => {
   if (event.type === "response.output_item.done") {
     if (event.item?.type === "message" && event.item.id === undefined)
       return ProviderShared.eventError(state.id, `${event.type} message is missing id`)
-    return onOutputItemDone(state, event)
+    return onOutputItemDone(state, event.item)
   }
   if (event.type === "response.completed" || event.type === "response.incomplete") return onResponseFinish(state, event)
   if (event.type === "response.failed") return providerFailure(event, `${state.name} response failed`)

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

@@ -815,7 +815,12 @@ const mapFinishReason = Effect.fn("OpenAIChat.mapFinishReason")(function* (event
     case "tool_calls":
       return "tool-calls" as const
     default:
-      return "unknown" as const
+      return yield* new AIError({
+        reason: new UnknownProviderError({
+          message: `Provider finish_reason: ${reason}`,
+          body: ProviderShared.encodeJson(event),
+        }),
+      })
   }
 })
 
@@ -1000,33 +1005,12 @@ const step = (state: ParserState, event: OpenAIChatEvent) =>
       lifecycle = Lifecycle.reasoningStart(lifecycle, events, "reasoning-0", deltaMetadata)
     const reasoningEmitted = state.reasoningEmitted || lifecycle.reasoning.has("reasoning-0")
 
-    if (delta?.content) {
-      lifecycle = Lifecycle.reasoningEnd(
-        lifecycle,
-        events,
-        "reasoning-0",
-        reasoningMetadata(
-          state.providerMetadataKey,
-          reasoningField,
-          reasoningDetailsObserved ? state.reasoningDetails : undefined,
-        ),
-      )
-      lifecycle = Lifecycle.textDelta(lifecycle, events, "text-0", delta.content)
-    }
+    // Reasoning is one response-wide channel: it stays open alongside text and
+    // refusal output so late reasoning deltas and details join the same block,
+    // and `finishEvents` closes it once with the complete metadata.
+    if (delta?.content) lifecycle = Lifecycle.textDelta(lifecycle, events, "text-0", delta.content)
 
-    if (delta?.refusal) {
-      lifecycle = Lifecycle.reasoningEnd(
-        lifecycle,
-        events,
-        "reasoning-0",
-        reasoningMetadata(
-          state.providerMetadataKey,
-          reasoningField,
-          reasoningDetailsObserved ? state.reasoningDetails : undefined,
-        ),
-      )
-      lifecycle = Lifecycle.textDelta(lifecycle, events, "text-0", delta.refusal)
-    }
+    if (delta?.refusal) lifecycle = Lifecycle.textDelta(lifecycle, events, "text-0", delta.refusal)
 
     // Compatible providers may omit indexes. Prefer durable identity, then use
     // batch position for parallel deltas or the latest call for sparse chunks.
@@ -1075,17 +1059,25 @@ const step = (state: ParserState, event: OpenAIChatEvent) =>
       events.push(...result.events)
     }
 
-    if (finishReason !== undefined && state.finishReason === undefined && Object.keys(pendingTools).length > 0)
+    const incompleteTools = finishReason?.normalized === "content-filter" || finishReason?.normalized === "length"
+    if (
+      finishReason !== undefined &&
+      !incompleteTools &&
+      state.finishReason === undefined &&
+      Object.keys(pendingTools).length
+    )
       return yield* ProviderShared.eventError(
         ADAPTER,
         "OpenAI Chat tool call delta is missing id or name",
         ProviderShared.encodeJson(event),
       )
 
-    // Finalize accumulated tool inputs eagerly when finish_reason arrives so
-    // valid calls and malformed local calls settle independently.
+    // Filtering or truncation terminates the response without confirming pending tool calls.
     const finished =
-      finishReason !== undefined && state.finishReason === undefined && Object.keys(tools).length > 0
+      finishReason !== undefined &&
+      !incompleteTools &&
+      state.finishReason === undefined &&
+      Object.keys(tools).length > 0
         ? yield* ToolStream.finishAll(ADAPTER, tools)
         : undefined
 
@@ -1132,10 +1124,12 @@ const finishEvents = Effect.fn("OpenAIChat.finishEvents")(function* (state: Pars
           state.finishReason.normalized === "stop" && hasToolCalls ? "tool-calls" : state.finishReason.normalized,
       }
     : { normalized: hasToolCalls ? ("tool-calls" as const) : ("stop" as const) }
+  // Snapshot details at publish time so the emitted event never observes later
+  // mutation of the accumulated `reasoningDetails` array.
   const metadata = reasoningMetadata(
     state.providerMetadataKey,
     state.reasoningField,
-    state.reasoningDetailsObserved ? state.reasoningDetails : undefined,
+    state.reasoningDetailsObserved ? [...state.reasoningDetails] : undefined,
   )
   const started =
     state.reasoningDetailsObserved && !state.reasoningEmitted

packages/ai/src/provider-error.ts

@@ -76,6 +76,8 @@ const INVALID_REQUEST_CODES = new Set(["invalid_prompt", "invalid_request_error"
 const RATE_LIMIT_TEXT = /rate increased too quickly|rate[-_\s]?limit|too[_\s]?many[_\s]?requests/i
 const QUOTA_TEXT = /insufficient[-_\s]?quota|quota[-_\s]?exceeded/i
 const CONTENT_POLICY_TEXT = /content[-_\s]?policy|content_filter|safety/i
+const SERVER_ERROR_TEXT =
+  /\b(?:try again|(?:please |you can )?retry (?:the |this |your )?request|try (?:the |this |your )?request again|(?:currently |temporarily )?at capacity|overloaded|temporarily unavailable|service[-_\s]?unavailable|(?:server|internal)[-_\s]?error|server (?:is )?busy|provider returned (?:an )?error|resource[-_\s]?exhausted|upstream (?:connect|connection|request)|request buffer limit while retrying upstream)\b/i
 
 export interface ProviderFailure {
   readonly message: string
@@ -139,6 +141,9 @@ export function classifyProviderFailure(input: ProviderFailure): AIError["reason
     input.status === 408 ||
     input.status === 409 ||
     (input.status !== undefined && input.status >= 500) ||
+    ((input.status === undefined || input.status < 400) &&
+      !codes.some((code) => INVALID_REQUEST_CODES.has(code)) &&
+      SERVER_ERROR_TEXT.test(text)) ||
     codes.some((code) => SERVER_CODES.has(code) || code.includes("exhausted") || code.includes("unavailable"))
   )
     return new ProviderInternalError({

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

@@ -81,6 +81,46 @@ describe("provider error classification", () => {
     ).toEqual(["ProviderInternal", "ProviderInternal", "ProviderInternal"])
   })
 
+  test("classifies retryable server messages as provider internal", () => {
+    const message =
+      "The model is currently at capacity due to high demand. Please try again in a few minutes, or use a higher service tier for priority processing."
+
+    expect(
+      [
+        message,
+        "Try again",
+        "Please retry your request shortly.",
+        "You can retry the request.",
+        "Try your request again.",
+        "The service is temporarily at capacity.",
+        "The model is overloaded.",
+        "Service unavailable",
+        "Internal server error",
+        "The server is busy.",
+        "Provider returned error",
+        "Provider returned an error",
+        "ResourceExhausted",
+        "Upstream connection failed",
+        "Exceeded request buffer limit while retrying upstream",
+      ].map((message) => classifyProviderFailure({ message })._tag),
+    ).toEqual(Array(15).fill("ProviderInternal"))
+    expect(
+      classifyProviderFailure({ message: "Provider request failed", rawBody: "Please try again later." })._tag,
+    ).toBe("ProviderInternal")
+  })
+
+  test("prioritizes specific failures over retryable server text", () => {
+    expect(
+      [
+        classifyProviderFailure({ message: "Invalid credentials, try again", status: 401 }),
+        classifyProviderFailure({ message: "Quota exceeded, try again", status: 429 }),
+        classifyProviderFailure({ message: "Rate limit exceeded, try again" }),
+        classifyProviderFailure({ message: "Upstream request failed: validation failed", status: 400 }),
+        classifyProviderFailure({ message: "Try again", status: 200 }),
+      ].map((failure) => failure._tag),
+    ).toEqual(["Authentication", "QuotaExceeded", "RateLimit", "InvalidRequest", "ProviderInternal"])
+  })
+
   test("classifies transient client statuses as provider internal", () => {
     expect([408, 409].map((status) => classifyProviderFailure({ message: `HTTP ${status}`, status })._tag)).toEqual([
       "ProviderInternal",
@@ -111,7 +151,6 @@ describe("provider error classification", () => {
     expect(classifyProviderFailure({ message: '{"type":"error","error":{"code":123}}' })._tag).toBe("UnknownProvider")
     expect(classifyProviderFailure({ message: "not-json" })._tag).toBe("UnknownProvider")
     expect(classifyProviderFailure({ message: "network error" })._tag).toBe("UnknownProvider")
-    expect(classifyProviderFailure({ message: "Provider returned error" })._tag).toBe("UnknownProvider")
   })
 })
 

packages/ai/test/provider/open-responses-finals.test.ts

@@ -0,0 +1,209 @@
+import { describe, expect } from "bun:test"
+import { Effect } from "effect"
+import { LLM, LLMEvent } from "../../src/index.js"
+import { OpenResponses } from "../../src/protocols/open-responses.js"
+import { configure } from "../../src/providers/openai-compatible-responses.js"
+import { LLMClient } from "../../src/route.js"
+import { it } from "../lib/effect.js"
+import { fixedResponse } from "../lib/http.js"
+import { sseEvents } from "../lib/sse.js"
+
+const request = LLM.request({
+  model: configure({ apiKey: "test-key", baseURL: "https://responses.example.test/v1" }).model("example-model"),
+  prompt: "Respond.",
+})
+const completed = { type: "response.completed", response: { id: "resp_1" } }
+const generate = (...events: OpenResponses.Event[]) =>
+  LLMClient.generate(request).pipe(Effect.provide(fixedResponse(sseEvents(...events))))
+
+describe("Open Responses completed item text", () => {
+  ;["Draft expanded", "D", "Replacement", ""].forEach((text) => {
+    it.effect(`replaces streamed text with completed item text ${JSON.stringify(text)}`, () =>
+      Effect.gen(function* () {
+        const response = yield* generate(
+          { type: "response.output_item.added", item: { type: "message", id: "msg_1", phase: "commentary" } },
+          { type: "response.output_text.delta", item_id: "msg_1", delta: "Draft" },
+          { type: "response.output_text.done", item_id: "msg_1", text: "Part final" },
+          {
+            type: "response.output_item.done",
+            item: { type: "message", id: "msg_1", phase: "final_answer", content: [{ type: "output_text", text }] },
+          },
+          completed,
+        )
+        expect(response.text).toBe(text)
+        expect(response.events.filter(LLMEvent.is.textDelta).map((event) => event.text)).toEqual(["Draft"])
+        expect(response.events.filter(LLMEvent.is.textEnd)).toEqual([
+          {
+            type: "text-end",
+            id: "msg_1",
+            text,
+            providerMetadata: { "openai-compatible": { itemId: "msg_1", phase: "final_answer" } },
+          },
+        ])
+      }),
+    )
+  })
+
+  it.effect("joins completed text and refusal parts without streamed text", () =>
+    Effect.gen(function* () {
+      const response = yield* generate(
+        { type: "response.output_item.added", item: { type: "message", id: "msg_1" } },
+        {
+          type: "response.output_item.done",
+          item: {
+            type: "message",
+            id: "msg_1",
+            content: [
+              { type: "output_text", text: "Answer. " },
+              { type: "refusal", refusal: "Cannot help." },
+            ],
+          },
+        },
+        completed,
+      )
+      expect(response.text).toBe("Answer. Cannot help.")
+      expect(response.events.filter(LLMEvent.is.textStart)).toHaveLength(1)
+      expect(response.events.filter(LLMEvent.is.textEnd)).toHaveLength(1)
+    }),
+  )
+
+  it.effect("does not create an empty text fragment for an empty completed message", () =>
+    Effect.gen(function* () {
+      const response = yield* generate(
+        { type: "response.output_item.added", item: { type: "message", id: "msg_1" } },
+        { type: "response.output_text.done", item_id: "msg_1", text: "" },
+        {
+          type: "response.output_item.done",
+          item: { type: "message", id: "msg_1", content: [{ type: "output_text", text: "" }] },
+        },
+        completed,
+      )
+      expect(response.message.content).toEqual([])
+      expect(response.events.filter(LLMEvent.is.textStart)).toEqual([])
+    }),
+  )
+})
+
+describe("Open Responses completed item reasoning", () => {
+  ;[
+    {
+      name: "summary",
+      summary: [
+        { type: "summary_text", text: "Final" },
+        { type: "summary_text", text: "summary" },
+      ],
+      content: [{ type: "reasoning_text", text: "Raw" }],
+      text: "Final\n\nsummary",
+    },
+    {
+      name: "raw text",
+      summary: [
+        { type: "summary_text", text: "" },
+        { type: "summary_text", text: "" },
+      ],
+      content: [{ type: "reasoning_text", text: "Raw" }],
+      text: "Raw",
+    },
+    {
+      name: "streamed fallback",
+      summary: [
+        { type: "summary_text", text: "" },
+        { type: "summary_text", text: "" },
+      ],
+      content: [
+        { type: "reasoning_text", text: "" },
+        { type: "reasoning_text", text: "" },
+      ],
+      text: "Draft",
+    },
+  ].forEach((fixture) => {
+    it.effect(`uses ${fixture.name} at item completion`, () =>
+      Effect.gen(function* () {
+        const response = yield* generate(
+          { type: "response.output_item.added", item: { type: "reasoning", id: "rs_1" } },
+          { type: "response.reasoning_summary_text.delta", item_id: "rs_1", delta: "Draft" },
+          { type: "response.reasoning_summary_text.done", item_id: "rs_1", text: "Part final" },
+          {
+            type: "response.output_item.done",
+            item: {
+              type: "reasoning",
+              id: "rs_1",
+              summary: fixture.summary,
+              content: fixture.content,
+              encrypted_content: "encrypted",
+            },
+          },
+          completed,
+        )
+        expect(response.reasoning).toBe(fixture.text)
+        expect(response.events.filter(LLMEvent.is.reasoningEnd)).toHaveLength(1)
+        expect(response.message.content.find((part) => part.type === "reasoning")?.providerMetadata).toEqual({
+          "openai-compatible": { itemId: "rs_1", reasoningEncryptedContent: "encrypted" },
+        })
+      }),
+    )
+  })
+
+  it.effect("replaces only the still-open summary without repeating earlier text", () =>
+    Effect.gen(function* () {
+      const response = yield* generate(
+        { type: "response.output_item.added", item: { type: "reasoning", id: "rs_1" } },
+        { type: "response.reasoning_summary_text.delta", item_id: "rs_1", summary_index: 0, delta: "First " },
+        { type: "response.reasoning_summary_part.added", item_id: "rs_1", summary_index: 1 },
+        { type: "response.reasoning_summary_text.delta", item_id: "rs_1", summary_index: 1, delta: "draft" },
+        {
+          type: "response.output_item.done",
+          item: {
+            type: "reasoning",
+            id: "rs_1",
+            summary: [
+              { type: "summary_text", text: "First " },
+              { type: "summary_text", text: "final" },
+            ],
+          },
+        },
+        completed,
+      )
+      expect(response.reasoning).toBe("First final")
+      expect(response.events.filter(LLMEvent.is.reasoningEnd).map((event) => event.text)).toEqual([undefined, "final"])
+    }),
+  )
+})
+;["response.completed", "response.incomplete"].forEach((type) => {
+  it.effect(`keeps streamed text when part finals are followed by ${type} without item completion`, () =>
+    Effect.gen(function* () {
+      const response = yield* generate(
+        { type: "response.output_item.added", item: { type: "message", id: "msg_1" } },
+        { type: "response.output_text.delta", item_id: "msg_1", content_index: 0, delta: "Hel" },
+        { type: "response.output_text.delta", item_id: "msg_1", content_index: 1, delta: "world" },
+        { type: "response.output_text.done", item_id: "msg_1", content_index: 0, text: "Hello " },
+        {
+          type: "response.content_part.done",
+          item_id: "msg_1",
+          content_index: 0,
+          part: { type: "output_text", text: "Hello " },
+        },
+        { type: "response.output_item.added", item: { type: "reasoning", id: "rs_1" } },
+        { type: "response.reasoning_summary_text.delta", item_id: "rs_1", delta: "Draft" },
+        { type: "response.reasoning_summary_text.done", item_id: "rs_1", text: "Part final" },
+        {
+          type: "response.reasoning_summary_part.done",
+          item_id: "rs_1",
+          summary_index: 0,
+          part: { type: "summary_text", text: "Part final" },
+        },
+        {
+          type,
+          response: {
+            id: "resp_1",
+            incomplete_details: type === "response.incomplete" ? { reason: "max_output_tokens" } : undefined,
+          },
+        },
+      )
+      expect(response.text).toBe("Helworld")
+      expect(response.reasoning).toBe("Draft")
+      expect(response.events.filter(LLMEvent.is.textEnd).map((event) => event.text)).toEqual([undefined])
+      expect(response.events.filter(LLMEvent.is.reasoningEnd).map((event) => event.text)).toEqual([undefined])
+    }),
+  )
+})

packages/ai/test/provider/open-responses-lifecycle.test.ts

@@ -129,7 +129,7 @@ describe("Open Responses basic-item lifecycles", () => {
     }),
   )
 
-  it.effect("preserves done-only encrypted reasoning without replaying its summary or late events", () =>
+  it.effect("preserves done-only reasoning text and encryption without replaying late events", () =>
     Effect.gen(function* () {
       const item = {
         type: "reasoning",
@@ -157,6 +157,7 @@ describe("Open Responses basic-item lifecycles", () => {
         {
           type: "reasoning-end",
           id: "rs_1",
+          text: "Not streamed",
           providerMetadata: { "openai-compatible": { itemId: "rs_1", reasoningEncryptedContent: "encrypted-state" } },
         },
       ])
@@ -301,7 +302,7 @@ describe("Open Responses basic-item lifecycles", () => {
     )
   })
 
-  it.effect("recovers pending items in completed output order with terminal encrypted metadata", () =>
+  it.effect("recovers pending calls without reconciling terminal reasoning", () =>
     Effect.gen(function* () {
       const events = yield* collect(
         {
@@ -325,11 +326,6 @@ describe("Open Responses basic-item lifecycles", () => {
         },
       )
       expect(events.slice(5, -2)).toEqual([
-        {
-          type: "reasoning-end",
-          id: "rs_1:0",
-          providerMetadata: { "openai-compatible": { itemId: "rs_1", reasoningEncryptedContent: "terminal-state" } },
-        },
         {
           type: "tool-input-end",
           id: "call_1",
@@ -341,8 +337,10 @@ describe("Open Responses basic-item lifecycles", () => {
           id: "call_1",
           name: "lookup",
           input: { query: "final" },
+          providerExecuted: undefined,
           providerMetadata: { "openai-compatible": { itemId: "fc_1" } },
         },
+        { type: "reasoning-end", id: "rs_1:0" },
       ])
     }),
   )

packages/ai/test/provider/openai-chat.test.ts

@@ -7,6 +7,7 @@ import {
   AIError,
   LLMEvent,
   LLMRequest,
+  LLMResponse,
   Message,
   LanguageModel,
   ToolCallPart,
@@ -1149,7 +1150,7 @@ describe("OpenAI Chat route", () => {
     }),
   )
 
-  it.effect("preserves scalar reasoning after content starts", () =>
+  it.effect("preserves scalar reasoning after content starts in one lifecycle", () =>
     Effect.gen(function* () {
       const details = [{ type: "reasoning.text", text: "detail", format: "unknown", index: 0 }]
       const response = yield* LLMClient.generate(request).pipe(
@@ -1166,8 +1167,35 @@ describe("OpenAI Chat route", () => {
       )
 
       expect(response.reasoning).toBe("detailscalar")
-      expect(response.events.filter(LLMEvent.is.reasoningStart)).toHaveLength(2)
-      expect(response.events.filter(LLMEvent.is.reasoningEnd)).toHaveLength(2)
+      expect(response.events.filter(LLMEvent.is.reasoningStart)).toHaveLength(1)
+      expect(response.events.filter(LLMEvent.is.reasoningEnd)).toHaveLength(1)
+      expect(response.message.content.filter((part) => part.type === "reasoning")).toHaveLength(1)
+      expect(response.message.content.find((part) => part.type === "reasoning")?.providerMetadata).toEqual({
+        openai: { reasoningField: "reasoning", reasoningDetails: details },
+      })
+    }),
+  )
+
+  it.effect("keeps one reasoning lifecycle across many content chunks", () =>
+    Effect.gen(function* () {
+      const details = [{ type: "reasoning.text", text: "thinking", format: "anthropic-claude-v1", index: 0 }]
+      const response = yield* LLMClient.generate(request).pipe(
+        Effect.provide(
+          fixedResponse(
+            sseEvents(
+              { choices: [{ delta: { reasoning: "thinking", reasoning_details: details } }] },
+              ...Array.from({ length: 25 }, (_, index) => deltaChunk({ content: `chunk-${index} ` })),
+              deltaChunk({}, "stop"),
+            ),
+          ),
+        ),
+      )
+
+      expect(response.reasoning).toBe("thinking")
+      expect(response.text).toBe(Array.from({ length: 25 }, (_, index) => `chunk-${index} `).join(""))
+      expect(response.events.filter(LLMEvent.is.reasoningStart)).toHaveLength(1)
+      expect(response.events.filter(LLMEvent.is.reasoningEnd)).toHaveLength(1)
+      expect(response.message.content.filter((part) => part.type === "reasoning")).toHaveLength(1)
       expect(response.message.content.find((part) => part.type === "reasoning")?.providerMetadata).toEqual({
         openai: { reasoningField: "reasoning", reasoningDetails: details },
       })
@@ -1213,7 +1241,18 @@ describe("OpenAI Chat route", () => {
           index: 0,
         },
       ]
-      const response = yield* LLMClient.generate(request).pipe(
+      // Snapshot reasoning-end metadata as each event is published so the
+      // assertion cannot pass through later mutation of a shared array.
+      const publishedEndMetadata: unknown[] = []
+      const response = yield* LLMClient.stream(request).pipe(
+        Stream.tap((event) =>
+          Effect.sync(() => {
+            if (LLMEvent.is.reasoningEnd(event))
+              publishedEndMetadata.push(decodeJson(encodeJson(event.providerMetadata)))
+          }),
+        ),
+        Stream.runFold(LLMResponse.empty, LLMResponse.reduce),
+        Effect.map((state) => LLMResponse.complete(state)!),
         Effect.provide(
           fixedResponse(
             sseEvents(
@@ -1234,10 +1273,12 @@ describe("OpenAI Chat route", () => {
       expect(response.events.filter(LLMEvent.is.reasoningStart)).toHaveLength(1)
       expect(response.events.filter(LLMEvent.is.reasoningDelta)).toHaveLength(1)
       expect(response.events.filter(LLMEvent.is.reasoningEnd)).toHaveLength(1)
-      expect(response.events.filter(LLMEvent.is.reasoningEnd).at(-1)?.providerMetadata).toEqual({
-        openai: { reasoningField: "reasoning", reasoningDetails: merged },
-      })
-      expect(response.events.findIndex(LLMEvent.is.reasoningEnd)).toBeLessThan(
+      expect(publishedEndMetadata).toEqual([{ openai: { reasoningField: "reasoning", reasoningDetails: merged } }])
+      expect(response.events.findIndex(LLMEvent.is.reasoningStart)).toBeLessThan(
+        response.events.findIndex(LLMEvent.is.textStart),
+      )
+      // Reasoning stays open alongside text and closes once during finalization.
+      expect(response.events.findIndex(LLMEvent.is.reasoningEnd)).toBeGreaterThan(
         response.events.findIndex(LLMEvent.is.textStart),
       )
 
@@ -1419,6 +1460,162 @@ describe("OpenAI Chat route", () => {
     }),
   )
 
+  it.effect("does not finalize streamed tool calls when content is filtered", () =>
+    Effect.gen(function* () {
+      const body = sseEvents(
+        deltaChunk({
+          tool_calls: [{ index: 0, id: "call_1", function: { name: "lookup", arguments: '{"query":"weather"' } }],
+        }),
+        deltaChunk({}, "content_filter"),
+      )
+      const response = yield* LLMClient.generate(
+        LLMRequest.update(request, {
+          tools: [ToolDefinition.make({ name: "lookup", description: "Lookup data", inputSchema: { type: "object" } })],
+        }),
+      ).pipe(Effect.provide(fixedResponse(body)))
+
+      expect(response.events).toEqual([
+        { type: "step-start", index: 0 },
+        {
+          type: "tool-input-start",
+          id: "call_1",
+          name: "lookup",
+          providerExecuted: undefined,
+          providerMetadata: undefined,
+        },
+        {
+          type: "tool-input-delta",
+          id: "call_1",
+          name: "lookup",
+          text: '{"query":"weather"',
+          input: { query: "weather" },
+        },
+        {
+          type: "step-finish",
+          index: 0,
+          reason: { normalized: "content-filter", raw: "content_filter" },
+          usage: undefined,
+          providerMetadata: undefined,
+        },
+        { type: "finish", reason: { normalized: "content-filter", raw: "content_filter" }, usage: undefined },
+      ])
+      expect(response.toolCalls).toEqual([])
+
+      const missingIdentity = yield* LLMClient.generate(request).pipe(
+        Effect.provide(
+          fixedResponse(
+            sseEvents(
+              deltaChunk({ tool_calls: [{ index: 0, id: "call_2", function: { arguments: "{}" } }] }),
+              deltaChunk({}, "content_filter"),
+            ),
+          ),
+        ),
+      )
+      expect(missingIdentity.finishReason).toEqual({ normalized: "content-filter", raw: "content_filter" })
+      expect(missingIdentity.toolCalls).toEqual([])
+    }),
+  )
+
+  it.effect("does not finalize streamed tool calls when output is truncated", () =>
+    Effect.gen(function* () {
+      const body = sseEvents(
+        deltaChunk({
+          tool_calls: [{ index: 0, id: "call_1", function: { name: "lookup", arguments: '{"query":"weather"}' } }],
+        }),
+        deltaChunk({}, "length"),
+      )
+      const response = yield* LLMClient.generate(
+        LLMRequest.update(request, {
+          tools: [ToolDefinition.make({ name: "lookup", description: "Lookup data", inputSchema: { type: "object" } })],
+        }),
+      ).pipe(Effect.provide(fixedResponse(body)))
+
+      expect(response.events).toEqual([
+        { type: "step-start", index: 0 },
+        {
+          type: "tool-input-start",
+          id: "call_1",
+          name: "lookup",
+          providerExecuted: undefined,
+          providerMetadata: undefined,
+        },
+        {
+          type: "tool-input-delta",
+          id: "call_1",
+          name: "lookup",
+          text: '{"query":"weather"}',
+          input: { query: "weather" },
+        },
+        {
+          type: "step-finish",
+          index: 0,
+          reason: { normalized: "length", raw: "length" },
+          usage: undefined,
+          providerMetadata: undefined,
+        },
+        { type: "finish", reason: { normalized: "length", raw: "length" }, usage: undefined },
+      ])
+      expect(response.toolCalls).toEqual([])
+
+      const missingIdentity = yield* LLMClient.generate(request).pipe(
+        Effect.provide(
+          fixedResponse(
+            sseEvents(
+              deltaChunk({ tool_calls: [{ index: 0, id: "call_2", function: { arguments: "{}" } }] }),
+              deltaChunk({}, "length"),
+            ),
+          ),
+        ),
+      )
+      expect(missingIdentity.finishReason).toEqual({ normalized: "length", raw: "length" })
+      expect(missingIdentity.toolCalls).toEqual([])
+    }),
+  )
+
+  it.effect("rejects unknown finish reasons without finalizing streamed tool calls", () =>
+    Effect.gen(function* () {
+      const body = sseEvents(
+        deltaChunk({
+          tool_calls: [{ index: 0, id: "call_1", function: { name: "lookup", arguments: '{"query":"weather"' } }],
+        }),
+        deltaChunk({}, "future_reason"),
+      )
+      const events = yield* Ref.make<ReadonlyArray<LLMEvent>>([])
+      const error = yield* LLMClient.stream(
+        LLMRequest.update(request, {
+          tools: [ToolDefinition.make({ name: "lookup", description: "Lookup data", inputSchema: { type: "object" } })],
+        }),
+      ).pipe(
+        Stream.tap((event) => Ref.update(events, (current) => [...current, event])),
+        Stream.runDrain,
+        Effect.provide(fixedResponse(body)),
+        Effect.flip,
+      )
+
+      expect(error).toMatchObject({
+        reason: { _tag: "UnknownProvider" },
+        message: "Provider finish_reason: future_reason",
+      })
+      expect(yield* Ref.get(events)).toEqual([
+        { type: "step-start", index: 0 },
+        {
+          type: "tool-input-start",
+          id: "call_1",
+          name: "lookup",
+          providerExecuted: undefined,
+          providerMetadata: undefined,
+        },
+        {
+          type: "tool-input-delta",
+          id: "call_1",
+          name: "lookup",
+          text: '{"query":"weather"',
+          input: { query: "weather" },
+        },
+      ])
+    }),
+  )
+
   it.effect("ignores empty identity fields on later tool call deltas", () =>
     Effect.gen(function* () {
       const body = sseEvents(

packages/ai/test/provider/openai-compatible-chat.test.ts

@@ -554,6 +554,19 @@ describe("OpenAI-compatible Chat route", () => {
         reason: { _tag: "UnknownProvider" },
         message: "Provider reported an error (finish_reason: error)",
       })
+
+      const unknown = yield* LLMClient.generate(request).pipe(
+        Effect.provide(fixedResponse(sseEvents(deltaChunk({}, "future_reason")))),
+        Effect.flip,
+      )
+      expect(unknown).toMatchObject({
+        reason: { _tag: "UnknownProvider" },
+        message: "Provider finish_reason: future_reason",
+      })
+      expect(decodeJson(unknown.reason.body ?? "")).toMatchObject({
+        id: "chatcmpl_fixture",
+        choices: [{ finish_reason: "future_reason" }],
+      })
     }),
   )
 
@@ -581,17 +594,13 @@ describe("OpenAI-compatible Chat route", () => {
     }),
   )
 
-  it.effect("preserves provider finish outcomes in the common reason algebra", () =>
+  it.effect("preserves content-filter finishes in the common reason algebra", () =>
     Effect.gen(function* () {
       const filtered = yield* LLMClient.generate(request).pipe(
         Effect.provide(fixedResponse(sseEvents(deltaChunk({}, "content_filter")))),
       )
-      const future = yield* LLMClient.generate(request).pipe(
-        Effect.provide(fixedResponse(sseEvents(deltaChunk({}, "future_reason")))),
-      )
 
       expect(filtered.finishReason).toEqual({ normalized: "content-filter", raw: "content_filter" })
-      expect(future.finishReason).toEqual({ normalized: "unknown", raw: "future_reason" })
     }),
   )
 

packages/ai/test/provider/openai-compatible-responses.test.ts

@@ -406,7 +406,7 @@ describe("Open Responses-compatible route", () => {
     })
 
     routings.forEach((routing) => {
-      it.effect(`preserves reasoning summary boundaries and terminal metadata with ${routing.name}`, () =>
+      it.effect(`preserves reasoning summary boundaries without terminal reconciliation with ${routing.name}`, () =>
         Effect.gen(function* () {
           const address = { item_id: routing.item_id, output_index: routing.output_index }
           const response = yield* LLMClient.generate(request).pipe(
@@ -444,21 +444,18 @@ describe("Open Responses-compatible route", () => {
               type: "reasoning",
               text: "Second.",
               providerMetadata: {
-                "openai-compatible": { itemId: routing.id, reasoningEncryptedContent: "final-state" },
+                "openai-compatible": { itemId: routing.id, reasoningEncryptedContent: null },
               },
             },
           ])
           expect(response.events.filter(LLMEvent.is.reasoningEnd)).toEqual([
-            expect.objectContaining({
+            {
+              type: "reasoning-end",
               id: `${routing.id}:0`,
+              text: undefined,
               providerMetadata: { "openai-compatible": { itemId: routing.id } },
-            }),
-            expect.objectContaining({
-              id: `${routing.id}:1`,
-              providerMetadata: {
-                "openai-compatible": { itemId: routing.id, reasoningEncryptedContent: "final-state" },
-              },
-            }),
+            },
+            { type: "reasoning-end", id: `${routing.id}:1` },
           ])
         }),
       )
@@ -671,7 +668,7 @@ describe("Open Responses-compatible route", () => {
     }),
   )
 
-  it.effect("preserves terminal reasoning metadata when item completion is missing", () =>
+  it.effect("ignores terminal reasoning output when item completion is missing", () =>
     Effect.gen(function* () {
       const model = configure({
         apiKey: "test-key",
@@ -697,8 +694,9 @@ describe("Open Responses-compatible route", () => {
         ),
       )
 
-      expect(response.events.find((event) => event.type === "reasoning-end")).toMatchObject({
-        providerMetadata: { "openai-compatible": { itemId: "rs_raw", reasoningEncryptedContent: "raw-state" } },
+      expect(response.events.find((event) => event.type === "reasoning-end")).toEqual({
+        type: "reasoning-end",
+        id: "rs_raw:0",
       })
     }),
   )

packages/ai/test/provider/openai-responses.test.ts

@@ -2554,7 +2554,7 @@ describe("OpenAI Responses route", () => {
     }),
   )
 
-  it.effect("preserves terminal reasoning metadata when output item completion is missing", () =>
+  it.effect("ignores terminal reasoning output when item completion is missing", () =>
     Effect.gen(function* () {
       const response = yield* LLMClient.generate(
         LLMRequest.update(request, { providerOptions: { store: false } }),
@@ -2595,29 +2595,13 @@ describe("OpenAI Responses route", () => {
 
       expect(response.reasoning).toBe("Checked the diff.")
       expect(response.events.filter((event) => event.type === "reasoning-end")).toEqual([
-        {
-          type: "reasoning-end",
-          id: "rs_1:0",
-          providerMetadata: { openai: { itemId: "rs_1", reasoningEncryptedContent: "terminal-state" } },
-        },
+        { type: "reasoning-end", id: "rs_1:0" },
       ])
       expect(response.message.content).toContainEqual({
         type: "reasoning",
         text: "Checked the diff.",
-        providerMetadata: { openai: { itemId: "rs_1", reasoningEncryptedContent: "terminal-state" } },
+        providerMetadata: { openai: { itemId: "rs_1", reasoningEncryptedContent: null } },
       })
-
-      const prepared = yield* compileRequest(
-        LLM.request({ model, messages: [response.message], providerOptions: { store: false } }),
-      )
-      expect(prepared.body.input).toEqual([
-        {
-          type: "reasoning",
-          id: "rs_1",
-          summary: [{ type: "summary_text", text: "Checked the diff." }],
-          encrypted_content: "terminal-state",
-        },
-      ])
     }),
   )
 
@@ -2644,7 +2628,7 @@ describe("OpenAI Responses route", () => {
     }),
   )
 
-  it.effect("reconciles pending reasoning and function calls in completed output order", () =>
+  it.effect("recovers pending function calls without reconciling terminal reasoning", () =>
     Effect.gen(function* () {
       const response = yield* LLMClient.generate(
         LLMRequest.update(request, { providerOptions: { store: false } }),
@@ -2682,14 +2666,15 @@ describe("OpenAI Responses route", () => {
         ),
       )
 
-      expect(response.events.find((event) => event.type === "reasoning-end")).toMatchObject({
-        providerMetadata: { openai: { itemId: "rs_1", reasoningEncryptedContent: "terminal-state" } },
+      expect(response.events.find((event) => event.type === "reasoning-end")).toEqual({
+        type: "reasoning-end",
+        id: "rs_1:0",
       })
       expect(response.events.filter(LLMEvent.is.toolCall)).toEqual([
         expect.objectContaining({ id: "call_1", input: { query: "weather" } }),
       ])
-      expect(response.events.findIndex((event) => event.type === "reasoning-end")).toBeLessThan(
-        response.events.findIndex(LLMEvent.is.toolCall),
+      expect(response.events.findIndex(LLMEvent.is.toolCall)).toBeLessThan(
+        response.events.findIndex((event) => event.type === "reasoning-end"),
       )
       expect(response.finishReason.normalized).toBe("tool-calls")
     }),
@@ -3019,6 +3004,7 @@ describe("OpenAI Responses route", () => {
         {
           type: "reasoning-end",
           id: "rs_1:0",
+          text: "Checked the diff.",
           providerMetadata: { openai: { itemId: "rs_1", reasoningEncryptedContent: "encrypted-state" } },
         },
       ])

packages/app/.gitignore

@@ -1,5 +1,6 @@
 src/assets/theme.css
 e2e/test-results
+e2e/performance/results/
 e2e/playwright-report
 component-tests/test-results
 component-tests/playwright-report

packages/app/README.md

@@ -71,4 +71,25 @@ Environment options:
 
 ## Deployment
 
-You can deploy the `dist` folder to any static host provider (netlify, surge, now, etc.)
+The `deploy` GitHub Actions workflow uses SST to deploy the web app from these branches in `anomalyco/opencode`:
+
+| Branch       | Site                  |
+| ------------ | --------------------- |
+| `dev`        | `app.dev.opencode.ai` |
+| `production` | `app.opencode.ai`     |
+| `beta`       | `beta.opencode.ai`    |
+
+Changes merged into `v2` reach the beta site when they are promoted to `beta`. The beta SST stage deploys
+only the web app, using the same `WebApp` StaticSite definition as production. It sets the build channel
+and Sentry environment to `beta` without deploying the API, console, database, or billing infrastructure.
+
+The hosted app defaults to `http://localhost:49374`, matching the managed V2 service. Saved server selections
+override this default. Connecting still requires the service's credentials.
+
+The workflow reuses the repository's `CLOUDFLARE_API_TOKEN` and web Sentry settings. The Cloudflare token
+must cover SST's R2 state storage, KV assets, Workers, and custom-domain management in the account that
+owns `opencode.ai`. The beta GitHub environment must allow deployments from the `beta` branch; it does not
+need AWS credentials.
+
+SST manages the beta site's custom domain. The first deployment creates its DNS record and TLS certificate.
+Do not create a CNAME for `beta.opencode.ai` first, because it would conflict with the Workers custom domain.

packages/app/component-tests/composer.spec.ts

@@ -1,5 +1,36 @@
 import { expect, story } from "../../storybook/playwright/story"
 
+story("renders a draft once and supports editing, caret restoration, and failure recovery", async ({ mount, page }) => {
+  await page.addInitScript(() => {
+    const replace = Element.prototype.replaceChildren
+    Element.prototype.replaceChildren = function (this: Element, ...nodes) {
+      // The ref can run before data-component is assigned, so count on every target.
+      this.setAttribute("data-test-replacements", String(Number(this.getAttribute("data-test-replacements")) + 1))
+      return replace.apply(this, nodes)
+    }
+  })
+  const component = await mount("opencode-composer-flow--failed-submission-restoration")
+  const input = component.getByRole("textbox", { name: "Prompt", exact: true })
+  await expect(input).toHaveText("Preserve this draft on failure")
+  await expect(input).toHaveAttribute("data-test-replacements", "1")
+
+  await input.press("Home")
+  await input.press("Shift+ArrowRight")
+  await input.pressSequentially("XY")
+  await expect(input).toHaveText("XYreserve this draft on failure")
+  await expect(input).toHaveAttribute("data-test-replacements", "1")
+
+  // Closing the model picker restores the controller's saved caret through its editor ref.
+  await component.locator('[data-action="composer-model"]').click()
+  await page.getByRole("menu").getByRole("textbox").press("Escape")
+  await expect(input).toBeFocused()
+  await input.pressSequentially("!")
+  await expect(input).toHaveText("XY!reserve this draft on failure")
+  await component.getByRole("button", { name: "Send", exact: true }).click()
+  await expect(component.getByRole("status")).toHaveText("Submission failed; draft restored")
+  await expect(input).toHaveText("Preserve this draft on failure")
+})
+
 // Moved from packages/app/e2e/regression/prompt-thinking-level.spec.ts
 story("shows the thinking level control while relevant", async ({ mount, page }) => {
   const component = await mount("opencode-composer-flow--model-and-variant")

packages/app/component-tests/timeline-virtualizer.fixture.tsx

@@ -0,0 +1,135 @@
+import { TimelineRow } from "@opencode-ai/session-ui/timeline/projection"
+import { onCleanup } from "solid-js"
+import { createStore } from "solid-js/store"
+import { render } from "solid-js/web"
+import { LanguageProvider } from "../src/runtime/i18n/language"
+import { createTimelineVirtualizer } from "../src/session/timeline/virtualizer"
+
+export function mountTimelineVirtualizer(input: { count: number; rowHeight: number; immediate?: boolean }) {
+  const host = document.createElement("main")
+  host.dataset.testid = "timeline-virtualizer-fixture"
+  host.dataset.scrolls = "0"
+  host.dataset.viewportResizes = "0"
+  host.style.cssText = "position:fixed;top:24px;right:24px;width:400px;z-index:1000"
+  document.body.appendChild(host)
+
+  function Fixture() {
+    const [state, setState] = createStore({ pinned: true, ready: false })
+    const rows = Array.from(
+      { length: input.count },
+      (_, index) => new TimelineRow.UserMessage({ userMessageID: `message-${index}` }),
+    )
+    const rowByKey = new Map(rows.map((row) => [TimelineRow.key(row), row]))
+    const indexes = new Map(rows.map((row, index) => [row.userMessageID, index]))
+    let viewport!: HTMLDivElement
+    let content!: HTMLDivElement
+    let container!: HTMLDivElement
+    const timeline = createTimelineVirtualizer({
+      sessionKey: () => "cold-reveal-fixture",
+      projection: {
+        rows: () => rows,
+        rowByKey: () => rowByKey,
+        activeMessageID: () => undefined,
+        messageRowIndex: () => indexes,
+        messageLastRowIndex: () => indexes,
+      },
+      showHeader: () => false,
+      pinned: () => state.pinned,
+      scroll: () => ({ overflow: false, jump: false }),
+      setScrollRef: (element) => {
+        if (!element) return
+        viewport = element
+        resize.observe(element, { box: "border-box" })
+      },
+      setContentRef: (element) => {
+        content = element
+        reveal.observe(element, { attributes: true, attributeFilter: ["style"] })
+      },
+      onPin: () => setState("pinned", true),
+      onUnpin: () => setState("pinned", false),
+      onScheduleScrollState: (element) => {
+        host.dataset.scrolls = String(Number(host.dataset.scrolls) + 1)
+        host.dataset.lastScrollTop = String(element.scrollTop)
+      },
+      onResumeScroll: () => {},
+      onSelectionInteraction: () => {},
+      onUserScroll: () => {},
+      onHistoryScroll: () => {},
+      canRenderImmediately: () => input.immediate ?? false,
+    })
+
+    const resize = new ResizeObserver((entries) => {
+      host.dataset.observedHeight = String(entries[0].borderBoxSize[0].blockSize)
+      host.dataset.viewportResizes = String(Number(host.dataset.viewportResizes) + 1)
+    })
+    const reveal = new MutationObserver(() => {
+      if (content.style.visibility === "hidden" || host.dataset.firstReveal) return
+      // Capture the first reveal, not a later frame after geometry has recovered.
+      const mounted = [...content.querySelectorAll<HTMLElement>("[data-timeline-key]")]
+      host.dataset.firstReveal = JSON.stringify({
+        rows: mounted.map((element) => Number(element.firstElementChild!.getAttribute("data-index"))),
+        pendingMarkdown: content.querySelectorAll('[data-component="markdown"]:not([data-markdown-ready])').length,
+        viewportHeight: viewport.clientHeight,
+        scrollTop: viewport.scrollTop,
+        clipped: mounted
+          .filter((element) => element.firstElementChild!.getBoundingClientRect().height > element.offsetHeight + 1)
+          .map((element) => element.dataset.timelineKey),
+      })
+    })
+    onCleanup(() => {
+      resize.disconnect()
+      reveal.disconnect()
+    })
+
+    return (
+      <div data-testid="timeline-controls" data-pinned={state.pinned}>
+        <button type="button" onClick={() => setState("ready", true)}>
+          Complete Markdown
+        </button>
+        <button type="button" onClick={() => (container.style.display = "none")}>
+          Hide viewport
+        </button>
+        <button
+          type="button"
+          onClick={() => {
+            const parent = viewport.parentElement!
+            host.dataset.scrolls = "0"
+            // Keep the same scroller and complete Markdown while it has no layout box.
+            viewport.remove()
+            viewport.scrollTop = 0
+            setState("ready", true)
+            parent.prepend(viewport)
+            container.style.removeProperty("display")
+          }}
+        >
+          Reconnect ready rows
+        </button>
+        <div ref={container} style={{ height: "180px", width: "400px" }}>
+          <timeline.View
+            header={null}
+            workspaceSession={() => false}
+            deferred={() => false}
+            renderRow={(row) => (
+              <div
+                data-component="markdown"
+                data-markdown-ready={state.ready ? "" : undefined}
+                style={{ height: `${input.rowHeight}px` }}
+              >
+                {row().userMessageID}
+              </div>
+            )}
+          />
+        </div>
+      </div>
+    )
+  }
+
+  render(
+    () => (
+      <LanguageProvider locale="en">
+        <Fixture />
+      </LanguageProvider>
+    ),
+    host,
+  )
+}

packages/app/component-tests/timeline-virtualizer.spec.ts

@@ -0,0 +1,79 @@
+import { fileURLToPath } from "node:url"
+import { expect, story } from "../../storybook/playwright/story"
+
+const fixture = `/@fs/${fileURLToPath(new URL("./timeline-virtualizer.fixture.tsx", import.meta.url)).replaceAll("\\", "/")}`
+
+story.beforeEach(async ({ mount }) => {
+  const component = await mount("opencode-composer-flow--mixed-attachments")
+  await expect(component.getByRole("textbox", { name: "Prompt", exact: true })).toBeVisible()
+})
+
+story("bounds the cheap suffix and reveals only ready measured rows", async ({ page }) => {
+  await page.evaluate(async (fixture) => {
+    const { mountTimelineVirtualizer } = await import(fixture)
+    mountTimelineVirtualizer({ count: 100, rowHeight: 60, immediate: true })
+  }, fixture)
+  const root = page.getByTestId("timeline-virtualizer-fixture")
+  const content = root.locator("[data-timeline-virtual-content]")
+  await expect(root).toHaveAttribute("data-observed-height", "180")
+  await expect(content).toHaveCSS("visibility", "hidden")
+  await expect(content.locator("[data-timeline-key]")).toHaveCount(4)
+  await root.getByRole("button", { name: "Complete Markdown", exact: true }).click()
+  await expect(content).toHaveCSS("visibility", "visible")
+  await expect(root).toHaveAttribute("data-first-reveal", /.+/)
+  expect(await root.evaluate((element) => JSON.parse(element.dataset.firstReveal!))).toMatchObject({
+    rows: [96, 97, 98, 99],
+    pendingMarkdown: 0,
+    clipped: [],
+    viewportHeight: 180,
+  })
+})
+
+for (const input of [
+  { name: "offset-only", count: 1, rowHeight: 600 },
+  { name: "zero-height", count: 4, rowHeight: 60 },
+]) {
+  story(`reveals ready measured rows after an ${input.name} reconnect`, async ({ page }) => {
+    await page.evaluate(
+      async ({ fixture, input }) => {
+        const { mountTimelineVirtualizer } = await import(fixture)
+        mountTimelineVirtualizer(input)
+      },
+      { fixture, input },
+    )
+    const root = page.getByTestId("timeline-virtualizer-fixture")
+    const content = root.locator("[data-timeline-virtual-content]")
+    await expect(root).toHaveAttribute("data-observed-height", "180")
+    await expect(content).toHaveCSS("visibility", "hidden")
+    await expect(content.locator("[data-timeline-key]")).toHaveCount(1)
+
+    if (input.name === "offset-only") {
+      await expect(root).toHaveAttribute("data-last-scroll-top", "484")
+      await root.locator("[data-scrollable]").dispatchEvent("wheel", { deltaY: -1 })
+      await expect(root.getByTestId("timeline-controls")).toHaveAttribute("data-pinned", "false")
+    }
+    if (input.name === "zero-height") {
+      await root.getByRole("button", { name: "Hide viewport", exact: true }).click()
+      // Wait for ResizeObserver to clear the actual range, not just for display:none.
+      await expect(root).toHaveAttribute("data-observed-height", "0")
+      await expect(content.locator("[data-timeline-key]")).toHaveCount(0)
+    }
+    await expect(root).not.toHaveAttribute("data-first-reveal")
+    const resizes = await root.getAttribute("data-viewport-resizes")
+    await root.getByRole("button", { name: "Reconnect ready rows", exact: true }).click()
+    await expect(content).toHaveCSS("visibility", "visible")
+    await expect(root).toHaveAttribute("data-first-reveal", /.+/)
+    expect(await root.evaluate((element) => JSON.parse(element.dataset.firstReveal!))).toMatchObject({
+      rows: input.count === 1 ? [0] : [0, 1, 2, 3],
+      pendingMarkdown: 0,
+      clipped: [],
+      viewportHeight: 180,
+      ...(input.name === "offset-only" ? { scrollTop: 0 } : {}),
+    })
+    if (input.name === "offset-only") {
+      // This repair must not depend on another native scroll or resize delivery.
+      await expect(root).toHaveAttribute("data-scrolls", "0")
+      await expect(root).toHaveAttribute("data-viewport-resizes", resizes!)
+    }
+  })
+}

packages/app/e2e/performance/README.md

@@ -65,7 +65,7 @@ The fixture requires every benchmark to call `report()`, automatically names and
 BENCHMARK {"name":"...","context":{"project":"chromium","platform":"darwin"},"metrics":{...}}
 ```
 
-Every observed page also emits `BENCHMARK_PAGE` with the same run ID, navigation history, and optional trace path before the final status-bearing `BENCHMARK` record. Chrome traces are browser-wide page-lifetime diagnostics; scenario metrics use narrower explicitly named observation windows.
+Every observed page also emits `BENCHMARK_PAGE` with the same run ID, navigation history, optional trace path, and trace scope before the final status-bearing `BENCHMARK` record. Chrome traces are browser-wide; the default window is page lifetime. Tab-switch traces begin after scenario setup and include explicit interaction markers. Scenario metrics use their own narrower observation windows.
 
 This follows the stack's own guidance: [Electron recommends repeated Chrome DevTools and Chrome Tracing measurement](https://www.electronjs.org/docs/latest/tutorial/performance), [Chrome DevTools recommends Performance recordings for runtime work](https://developer.chrome.com/docs/devtools/performance), and [Playwright uses traces for test debugging rather than renderer profiling](https://playwright.dev/docs/trace-viewer).
 
@@ -81,13 +81,60 @@ Committed smoke and regression tests continue to own correctness coverage for pa
 
 Tab-switch timing starts at `mousedown`, when mouse-selected tabs actually navigate, with a `click` fallback for keyboard activation. The probe excludes hidden/transparent content and intersects answers with their virtual-row clip and viewport. The tab workload requires the destination's final answer to be visible with Markdown ready. These results are not directly comparable to older click-start, geometry-only measurements. `stableObservedMs` includes confirmation across three correct samples; `firstCorrectObservedMs` is the first sample meeting all content and geometry checks. Neither is a compositor presentation timestamp.
 
-Each tab scenario reports one sample, including its raw observations. Use Playwright's `--repeat-each=5` for repeated measurements. Cached scenarios warm the destination at the same panel width before leaving it; a separate resized scenario validates reuse after opening the review pane changes that width.
+Each tab scenario reports one sample, including its raw observations. Use Playwright's `--repeat-each=20` for a baseline distribution. Warm scenarios prepare the destination at the same panel width before leaving it; a separate resized scenario validates reuse after opening the review pane changes that width.
+
+The tab-switch workload uses two equally long sessions: 200 user/assistant exchanges (400 messages) per tab. Every answer includes headings, emphasis, links, a blockquote, task and nested lists, an eight-row table, and four highlighted code fences (TSX, JSON, SQL, Bash), alongside the stress fixture's reasoning and tools. The mock API deliberately returns all 400 messages in one response so every scenario measures a long loaded history, not a short paginated tail. The viewport is fixed at 1440 x 900. Results include the fixture version, Markdown and serialized-message byte counts, and message-request count. These numbers are not directly comparable to the earlier 12-exchange source / 72-exchange destination fixture.
+
+Cold means the destination transcript has never rendered in that fresh browser context. Warm means its complex answer was rendered and ready before switching away and back. Both use the app's normal restored-tab data prefetch, which completes before measurement; neither includes app startup, the source session's Markdown engine initialization, or a cold backend fetch. The suite asserts no message fetch during either measured switch. Setup waits for mounted Markdown to finish and for the review-pane width transition to complete. Service workers are blocked to exclude the web build's background asset precache from this renderer benchmark. Screenshots are attached after measurement for the first repetition; Playwright video and trace recording are disabled for this workload, while opt-in Chrome profiling remains available. For a baseline distribution, use `--repeat-each=20 --retries=0`, keep profiling disabled, and report the median and p95 of `firstCorrectObservedMs` separately from the three-observation `stableObservedMs`.
 
 ```sh
 bunx playwright test --config e2e/performance/playwright.config.ts \
-  timeline/session-tab-switch-benchmark.spec.ts --repeat-each=5
+  timeline/session-tab-switch-benchmark.spec.ts --repeat-each=20 --retries=0
 ```
 
+**The tab-switch fixture is not an end-to-end cold-data benchmark.** It prefetches destination messages and returns full history. Measure cold API navigation, Home-row opening, and prefetched-but-unvisited tabs separately with normal pagination. Do not combine these entry paths or compare different transports and machine-load periods as one experiment.
+
+Keep one-off reports, recorded results, and traces outside git, in the ignored `e2e/performance/results/` directory or an external artifact directory. Preserve raw observations locally and publish anonymized summaries and charts in the PR description, not as committed experiment files.
+
+For a repeatable tab-switch summary, run from `packages/app`:
+
+```sh
+bun run bench:tabs
+```
+
+This runs only the tab-switch benchmark against the production build with 20 serial repetitions and no retries. It prints the median (mean of the two middle values for even sample counts) and nearest-rank p95 for `firstCorrectObservedMs` and `stableObservedMs` per scenario. Only records whose benchmark and Playwright statuses are passed and whose two metrics are finite enter the summary. Test and record statuses, missing records, and excluded samples are reported separately.
+
+For fresh entry paths, run `bun run bench:entry` from `packages/app`. It uses the same production, serial-repetition, and reporting defaults. The cases open an empty draft from the actual Home button, create a draft with the titlebar plus from an active session, and open a cold paginated session from Home. Draft readiness requires a focused editable composer, the expected model, project control, and new tab; typing and absence of backend mutations are checked afterward. Session readiness requires the latest group, ready answer Markdown, and bottom anchoring. These cases are separate from prefetched tab remounts.
+
+For milestone charts, rerun frozen builds with one workload and counterbalanced serial order. Do not connect historical medians from different transports, preparation, or machine-load periods. Show samples or ranges, name the checkpoints accurately, and distinguish experimental build snapshots from Git commits.
+
+Complete original `BENCHMARK` JSON records, including samples, context, and failed records, are saved as `tab-switch-benchmark.jsonl` in Playwright's configured output directory (default: `e2e/test-results/performance`). Standard Playwright flags can override defaults when appended:
+
+```sh
+bun run bench:tabs --repeat-each=3 --output=e2e/test-results/tabs-smoke
+```
+
+Set `OPENCODE_PERFORMANCE_MEMORY=1` for an opt-in renderer-main-isolate heap and DOM sample after mounted content is ready and an explicit GC completes. Probe DOM references are released before collection. This is not total desktop memory; do not mix these diagnostic runs with unprofiled latency samples. Set `OPENCODE_PERFORMANCE_TRACE_DIR` for a separate Chrome trace of each tab interaction, starting after preparation, with `session-switch:start`, `session-switch:ready`, and `session-switch:stable` markers.
+
+### Cache-Enabled HTTP Fixture
+
+The default tab harness uses Playwright routing for API responses. Playwright routing disables the browser HTTP cache, including for unrelated SVG assets. To measure with HTTP caching enabled, the same API handlers and tab data can run on a real loopback HTTP endpoint:
+
+```sh
+bun run build
+bun e2e/performance/tab-switch-server.ts --port 4639 --dist dist
+```
+
+With that fixture running, run the benchmark in a separate terminal from `packages/app`:
+
+```powershell
+$env:PLAYWRIGHT_BASE_URL = "http://127.0.0.1:4639"
+$env:OPENCODE_PERFORMANCE_HTTP_FIXTURE = "1"
+bun run bench:tabs
+```
+
+Use `--dist` to select a frozen production bundle when comparing revisions. An explicit `PLAYWRIGHT_BASE_URL` means the benchmark does not rebuild or start another preview. The fixture gives hashed assets immutable cache headers; it serves the deterministic read workload, not the live OpenCode service. Each test still gets a fresh browser context, and source-session setup still occurs before the measured switch. API responses use `no-store`, service workers remain blocked, and no destination Markdown is rendered before a cold switch. Records identify the transport as `http` or `playwright-route`; keep these series separate. Unset `OPENCODE_PERFORMANCE_HTTP_FIXTURE` when returning to the default routed harness.
+
 ## Retained renderer memory
 
 Run the catalog workload against the production app bundle:
@@ -111,7 +158,7 @@ bunx playwright test --config e2e/performance/playwright.config.ts \
 
 The emitted JSON is a standard Chrome trace and can be loaded directly into the Chrome DevTools Performance panel. `devtools-tracing` can optionally inspect it from the command line without adding package scripts or dependencies:
 
-Trace capture mirrors [Puppeteer's official tracing defaults and lifecycle](https://pptr.dev/api/puppeteer.tracing), using Chrome's `ReturnAsStream` transfer mode and failing when Chromium reports trace data loss.
+Trace capture follows [Puppeteer's tracing lifecycle](https://pptr.dev/api/puppeteer.tracing), using Chrome's `ReturnAsStream` transfer mode and failing when Chromium reports trace data loss. V8 CPU sample stacks support attribution through the frozen build's source maps. Set `OPENCODE_PERFORMANCE_STACK_TRACE=1` only when per-event timeline stacks are needed; they add substantial overhead. Keep profiled runs separate from latency distributions, including when comparing the stack-capture modes.
 
 ```sh
 bunx devtools-tracing stats <trace-path-from-BENCHMARK_PAGE>

packages/app/e2e/performance/benchmark.ts

@@ -5,16 +5,20 @@ type BenchmarkFixtures = {
   report: (metrics: Record<string, unknown>, context?: Record<string, unknown>) => void
   reportState: { payload?: { metrics: Record<string, unknown>; context: Record<string, unknown> } }
   benchmarkResult: void
+  traceScope: "page" | "interaction"
 }
 
 export type PerformancePageDiagnostics = {
   navigations: string[]
+  traceScope: "page" | "interaction"
+  startTrace: () => Promise<void>
   stop: () => Promise<string | undefined>
 }
 
 const pages = new WeakMap<Page, PerformancePageDiagnostics>()
 
 export const benchmark = base.extend<BenchmarkFixtures>({
+  traceScope: ["page", { option: true }],
   reportState: async ({}, use) => use({}),
   report: async ({ reportState }, use) => {
     await use((metrics, context = {}) => {
@@ -49,9 +53,9 @@ export const benchmark = base.extend<BenchmarkFixtures>({
     },
     { auto: true },
   ],
-  page: async ({ page }, use, testInfo) => {
+  page: async ({ page, traceScope }, use, testInfo) => {
     const name = benchmarkName(testInfo)
-    const diagnostics = await observePerformancePage(page, name)
+    const diagnostics = await observePerformancePage(page, name, traceScope)
     try {
       await use(page)
     } finally {
@@ -75,25 +79,30 @@ function benchmarkName(testInfo: TestInfo) {
 
 export { expect }
 
-async function observePerformancePage(page: Page, name: string) {
+async function observePerformancePage(page: Page, name: string, traceScope: "page" | "interaction" = "page") {
   const navigations: string[] = []
   const onNavigation = (frame: ReturnType<Page["mainFrame"]>) => {
     if (frame === page.mainFrame()) navigations.push(frame.url())
   }
   page.on("framenavigated", onNavigation)
-  const stopTrace = await startChromeTrace(page, name).catch((error) => {
-    page.off("framenavigated", onNavigation)
-    throw error
-  })
+  let stopTrace: Awaited<ReturnType<typeof startChromeTrace>>
   let stopping: Promise<string | undefined> | undefined
   const diagnostics: PerformancePageDiagnostics = {
     navigations,
+    traceScope,
+    async startTrace() {
+      stopTrace ??= await startChromeTrace(page, name).catch((error) => {
+        page.off("framenavigated", onNavigation)
+        throw error
+      })
+    },
     stop() {
       page.off("framenavigated", onNavigation)
       return (stopping ??= stopTrace?.() ?? Promise.resolve(undefined))
     },
   }
   pages.set(page, diagnostics)
+  if (traceScope === "page") await diagnostics.startTrace()
   return diagnostics
 }
 
@@ -130,6 +139,7 @@ async function reportPerformancePage(name: string, diagnostics: PerformancePageD
       context: {
         platform: process.platform,
         trace,
+        traceScope: diagnostics.traceScope,
         selectorTrace: process.env.OPENCODE_PERFORMANCE_SELECTOR_TRACE === "1",
       },
       navigations: diagnostics.navigations,

packages/app/e2e/performance/chrome-trace.ts

@@ -14,7 +14,6 @@ const categories = [
   "blink.console",
   "blink.user_timing",
   "latencyInfo",
-  "disabled-by-default-devtools.timeline.stack",
   "disabled-by-default-v8.cpu_profiler",
 ]
 
@@ -34,6 +33,9 @@ export async function startChromeTrace(page: Page, name: string): Promise<undefi
           .map((category) => category.slice(1)),
         includedCategories: [
           ...categories.filter((category) => !category.startsWith("-")),
+          ...(process.env.OPENCODE_PERFORMANCE_STACK_TRACE === "1"
+            ? ["disabled-by-default-devtools.timeline.stack"]
+            : []),
           ...(selectors
             ? ["disabled-by-default-blink.debug", "disabled-by-default-devtools.timeline.invalidationTracking"]
             : []),

packages/app/e2e/performance/tab-switch-reporter.ts

@@ -0,0 +1,99 @@
+import type { FullConfig, FullResult, Reporter, Suite, TestCase, TestResult } from "@playwright/test/reporter"
+import { mkdir, writeFile } from "node:fs/promises"
+import path from "node:path"
+
+type BenchmarkRecord = {
+  status?: string
+  metrics?: { firstCorrectObservedMs?: unknown; stableObservedMs?: unknown } | null
+}
+
+export default class TabSwitchReporter implements Reporter {
+  private output = ""
+  private tests: TestCase[] = []
+  private results: { test: TestCase; status: TestResult["status"]; records: string[] }[] = []
+
+  onBegin(config: FullConfig, suite: Suite) {
+    this.output = config.projects[0].outputDir
+    this.tests = suite.allTests()
+  }
+
+  onTestEnd(test: TestCase, result: TestResult) {
+    this.results.push({
+      test,
+      status: result.status,
+      records: Buffer.concat(result.stdout.map((chunk) => (typeof chunk === "string" ? Buffer.from(chunk) : chunk)))
+        .toString("utf8")
+        .split(/\r?\n/)
+        .filter((line) => line.startsWith("BENCHMARK "))
+        .map((line) => line.slice("BENCHMARK ".length)),
+    })
+  }
+
+  async onEnd(result: FullResult) {
+    const file = path.join(this.output, "tab-switch-benchmark.jsonl")
+    try {
+      await mkdir(this.output, { recursive: true })
+      await writeFile(file, this.results.flatMap((entry) => entry.records.map((raw) => `${raw}\n`)).join(""), "utf8")
+    } catch (error) {
+      console.error("Could not save tab-switch benchmark records:", error)
+      return { status: "failed" as const }
+    }
+
+    console.log(`\nTab-switch benchmark: ${result.status}`)
+    Array.from(new Set(this.tests.map((test) => test.title))).forEach((name) => {
+      const results = this.results.filter((entry) => entry.test.title === name)
+      const unrun = this.tests.filter(
+        (test) => test.title === name && !results.some((entry) => entry.test.id === test.id),
+      ).length
+      const records = results.flatMap((entry) =>
+        entry.records.map((raw) => {
+          try {
+            return { status: entry.status, record: JSON.parse(raw) as BenchmarkRecord | null }
+          } catch {
+            return { status: entry.status, record: { status: "invalid JSON", metrics: null } }
+          }
+        }),
+      )
+      const passed = records.filter((entry) => entry.status === "passed" && entry.record?.status === "passed")
+      const valid = passed
+        .map((entry) => ({
+          firstCorrectObservedMs: entry.record?.metrics?.firstCorrectObservedMs,
+          stableObservedMs: entry.record?.metrics?.stableObservedMs,
+        }))
+        .filter(
+          (metrics): metrics is { firstCorrectObservedMs: number; stableObservedMs: number } =>
+            typeof metrics.firstCorrectObservedMs === "number" &&
+            Number.isFinite(metrics.firstCorrectObservedMs) &&
+            typeof metrics.stableObservedMs === "number" &&
+            Number.isFinite(metrics.stableObservedMs),
+        )
+
+      console.log(`\n${name}`)
+      console.log(`  Tests: ${counts(results.map((entry) => entry.status))}; unrun=${unrun}`)
+      console.log(
+        `  Records: ${counts(records.map((entry) => entry.record?.status ?? "missing status"))}; ` +
+          `missing=${results.filter((entry) => entry.records.length === 0).length + unrun}; ` +
+          `excluded=${records.length - valid.length}; invalid metrics=${passed.length - valid.length}`,
+      )
+      ;(["firstCorrectObservedMs", "stableObservedMs"] as const).forEach((metric) => {
+        const values = valid.map((entry) => entry[metric]).sort((a, b) => a - b)
+        if (values.length === 0) {
+          console.log(`  ${metric}: n=0, median=n/a, p95=n/a`)
+          return
+        }
+        const median = (values[Math.floor((values.length - 1) / 2)] + values[Math.floor(values.length / 2)]) / 2
+        const p95 = values[Math.ceil(values.length * 0.95) - 1]
+        console.log(`  ${metric}: n=${values.length}, median=${median.toFixed(2)} ms, p95=${p95.toFixed(2)} ms`)
+      })
+    })
+    console.log(`\nRaw BENCHMARK records: ${file}`)
+  }
+}
+
+function counts(statuses: string[]) {
+  return (
+    Array.from(new Set(statuses))
+      .map((status) => `${status}=${statuses.filter((value) => value === status).length}`)
+      .join(", ") || "none"
+  )
+}

packages/app/e2e/performance/tab-switch-server.ts

@@ -0,0 +1,61 @@
+import path from "node:path"
+import { parseArgs } from "node:util"
+import { createMockServerHandler } from "../utils/mock-server"
+import { fixture } from "./timeline/session-timeline-stress.fixture"
+import { messages } from "./timeline/session-tab-switch.fixture"
+import { createReviewDiffs } from "./timeline/timeline-test-helpers"
+
+const args = parseArgs({
+  args: Bun.argv.slice(2),
+  options: { port: { type: "string", default: "4639" }, dist: { type: "string", default: "dist" } },
+})
+const directory = path.resolve(args.values.dist)
+const api = createMockServerHandler({
+  directory: fixture.directory,
+  project: fixture.project,
+  provider: fixture.provider,
+  sessions: fixture.sessions,
+  pageMessages: (sessionID) => ({ items: messages[sessionID] ?? [] }),
+  vcsDiff: createReviewDiffs(),
+})
+const server = Bun.serve({
+  hostname: "127.0.0.1",
+  port: Number(args.values.port),
+  idleTimeout: 0,
+  async fetch(request) {
+    const url = new URL(request.url)
+    if (url.pathname === "/api/event") {
+      return new Response(
+        new ReadableStream({
+          start(controller) {
+            controller.enqueue(
+              new TextEncoder().encode('data: {"id":"evt_fixture_connected","type":"server.connected","data":{}}\n\n'),
+            )
+          },
+        }),
+        { headers: { "content-type": "text/event-stream", "cache-control": "no-store" } },
+      )
+    }
+    if (url.pathname.startsWith("/api/")) {
+      const response = await api.handler(request)
+      response.headers.set("cache-control", "no-store")
+      return response
+    }
+    const file = Bun.file(path.join(directory, url.pathname))
+    if (!url.pathname.endsWith("/") && (await file.exists())) {
+      return new Response(file, {
+        headers: {
+          "cache-control": url.pathname.startsWith("/_assets/") ? "public, max-age=31536000, immutable" : "no-cache",
+        },
+      })
+    }
+    return new Response(Bun.file(path.join(directory, "index.html")), { headers: { "cache-control": "no-cache" } })
+  },
+})
+console.log(`Tab fixture: ${server.url} (${directory})`)
+const close = async () => {
+  await server.stop(true)
+  await api.dispose()
+}
+process.once("SIGINT", close)
+process.once("SIGTERM", close)

packages/app/e2e/performance/timeline/navigation-milestones.spec.ts

@@ -0,0 +1,33 @@
+import type { NavigationMilestoneSample } from "./navigation-milestones"
+import { measureNavigationMilestones } from "./navigation-milestones"
+import { benchmark, expect } from "../benchmark"
+
+benchmark(
+  "navigation milestones start at mousedown and wait for the expected ready controls",
+  async ({ page, report }) => {
+    await page.setContent('<button id="open">Open</button><input id="editor" disabled><span id="model">Loading</span>')
+    const result = await measureNavigationMilestones(page, {
+      triggerSelector: "#open",
+      milestones: { editor: { selector: "#editor:enabled:focus" }, model: { selector: "#model", text: "Ready model" } },
+      navigate: async () => {
+        await page.getByRole("button", { name: "Open", exact: true }).dispatchEvent("mousedown", { button: 0 })
+        await page.locator("#editor").evaluate((element: HTMLInputElement) => {
+          element.disabled = false
+          element.focus()
+        })
+        await page.waitForFunction(() => {
+          const samples = (window as Window & { __navigationMilestones?: { samples: NavigationMilestoneSample[] } })
+            .__navigationMilestones?.samples
+          return samples?.some((sample) => sample.milestones.editor && !sample.milestones.model)
+        })
+        await page.locator("#model").evaluate((element) => {
+          element.textContent = "Ready model"
+        })
+      },
+    })
+    expect(result.summary.all.firstObservedMs).not.toBeNull()
+    expect(result.summary.all.firstObservedMs).toBeGreaterThan(result.summary.milestones.editor.firstObservedMs!)
+    expect(await page.evaluate(() => "__navigationMilestones" in window)).toBe(false)
+    report(result)
+  },
+)

packages/app/e2e/performance/timeline/navigation-milestones.ts

@@ -36,7 +36,7 @@ export async function measureNavigationMilestones(
   page: Page,
   input: {
     triggerSelector: string
-    milestones: Record<string, { selector: string; visible?: boolean }>
+    milestones: Record<string, { selector: string; visible?: boolean; text?: string }>
     navigate: () => Promise<void>
   },
 ) {
@@ -47,11 +47,19 @@ export async function measureNavigationMilestones(
       const marked = new Set<string>()
       let started: number | undefined
       let running = true
-      const visible = (selector: string) =>
+      const visible = (selector: string, text?: string) =>
         [...document.querySelectorAll<HTMLElement>(selector)].some((element) => {
+          if (!element.checkVisibility({ checkOpacity: true, checkVisibilityCSS: true })) return false
+          if (text !== undefined && element.textContent?.replace(/\s+/g, " ").trim() !== text) return false
           const rect = element.getBoundingClientRect()
-          const style = getComputedStyle(element)
-          return rect.width > 0 && rect.height > 0 && style.visibility !== "hidden" && style.display !== "none"
+          return (
+            rect.width > 0 &&
+            rect.height > 0 &&
+            rect.bottom > 0 &&
+            rect.top < innerHeight &&
+            rect.right > 0 &&
+            rect.left < innerWidth
+          )
         })
       const sample = () => {
         if (!running || started === undefined) return
@@ -61,7 +69,9 @@ export async function measureNavigationMilestones(
             const current = Object.fromEntries(
               Object.entries(milestones).map(([name, milestone]) => [
                 name,
-                milestone.visible === false ? !document.querySelector(milestone.selector) : visible(milestone.selector),
+                milestone.visible === false
+                  ? !document.querySelector(milestone.selector)
+                  : visible(milestone.selector, milestone.text),
               ]),
             )
             samples.push({
@@ -93,36 +103,46 @@ export async function measureNavigationMilestones(
           }, 0)
         })
       }
-      document.addEventListener(
-        "click",
-        (event) => {
-          if (!(event.target instanceof Element) || !event.target.closest(triggerSelector)) return
-          started = performance.now()
-          performance.mark("opencode.navigation.click")
-          sample()
-        },
-        { capture: true, once: true },
-      )
+      const start = (event: MouseEvent) => {
+        if (started !== undefined || event.button !== 0) return
+        if (!(event.target instanceof Element) || !event.target.closest(triggerSelector)) return
+        started = performance.now()
+        performance.mark("opencode.navigation.start")
+        sample()
+      }
+      document.addEventListener("mousedown", start, true)
+      document.addEventListener("click", start, true)
       ;(window as Window & { __navigationMilestones?: NavigationMilestoneProbe }).__navigationMilestones = {
         samples,
         stop: () => {
           running = false
+          document.removeEventListener("mousedown", start, true)
+          document.removeEventListener("click", start, true)
         },
       }
     },
     { triggerSelector: input.triggerSelector, milestones: input.milestones },
   )
-  await input.navigate()
-  await page.waitForFunction(() => {
-    const samples = (window as Window & { __navigationMilestones?: NavigationMilestoneProbe }).__navigationMilestones
-      ?.samples
-    if (!samples || samples.length < 3) return false
-    return samples.slice(-3).every((sample) => Object.values(sample.milestones).every(Boolean))
-  })
-  const samples = await page.evaluate(() => {
-    const probe = (window as Window & { __navigationMilestones?: NavigationMilestoneProbe }).__navigationMilestones!
-    probe.stop()
-    return probe.samples
-  })
-  return { summary: summarizeNavigationMilestones(samples), samples }
+  try {
+    await input.navigate()
+    await page.waitForFunction(() => {
+      const samples = (window as Window & { __navigationMilestones?: NavigationMilestoneProbe }).__navigationMilestones
+        ?.samples
+      return (
+        samples &&
+        samples.length >= 3 &&
+        samples.slice(-3).every((sample) => Object.values(sample.milestones).every(Boolean))
+      )
+    })
+    const samples = await page.evaluate(
+      () => (window as Window & { __navigationMilestones?: NavigationMilestoneProbe }).__navigationMilestones!.samples,
+    )
+    return { summary: summarizeNavigationMilestones(samples), samples }
+  } finally {
+    await page.evaluate(() => {
+      const host = window as Window & { __navigationMilestones?: NavigationMilestoneProbe }
+      host.__navigationMilestones?.stop()
+      delete host.__navigationMilestones
+    })
+  }
 }

packages/app/e2e/performance/timeline/session-entry-benchmark.spec.ts

@@ -0,0 +1,91 @@
+import { benchmark, benchmarkDiagnostics, expect } from "../benchmark"
+import { measureNavigationMilestones } from "./navigation-milestones"
+import { fixture } from "./session-timeline-stress.fixture"
+import { measureSessionSwitch, waitForStableTimeline } from "./session-tab-switch-probe"
+import { installStressSessionTabs, mockStressTimeline, stressSessionHref } from "./timeline-test-helpers"
+
+benchmark.use({
+  viewport: { width: 1440, height: 900 },
+  serviceWorkers: "block",
+  traceScope: "interaction",
+  trace: "off",
+  video: "off",
+})
+
+for (const entry of ["home", "session"] as const) {
+  benchmark(`entry: new session from ${entry}`, async ({ page, report }) => {
+    await mockStressTimeline(page)
+    await installStressSessionTabs(page, { sessionIDs: entry === "home" ? [] : [fixture.sourceID] })
+    await page.goto(entry === "home" ? "/" : stressSessionHref(fixture.sourceID))
+    if (entry === "session") await waitForStableTimeline(page, fixture.expected.sourceMessageIDs.at(-1)!)
+    const trigger = entry === "home" ? '[data-action="home-new-session"]' : 'button[aria-label="New session"]'
+    await expect(page.locator(trigger)).toBeVisible()
+    await expect(page.locator('[data-component="new-session"]')).toHaveCount(0)
+    const writes: string[] = []
+    page.on("request", (request) => {
+      if (new URL(request.url()).pathname.startsWith("/api/") && !["GET", "HEAD", "OPTIONS"].includes(request.method()))
+        writes.push(request.method())
+    })
+    await benchmarkDiagnostics(page).startTrace()
+    const result = await measureNavigationMilestones(page, {
+      triggerSelector: trigger,
+      milestones: {
+        editor: {
+          selector: '[data-component="new-session"] [data-component="composer-editor"][contenteditable="true"]:focus',
+        },
+        model: { selector: '[data-component="new-session"] [data-action="composer-model"]', text: "Claude Opus 4.6" },
+        project: { selector: '[data-component="new-session"] [data-action="prompt-project"]' },
+        tab: { selector: '[data-titlebar-tab-link][href^="/new-session?draftId="]' },
+      },
+      navigate: () => page.locator(trigger).click(),
+    })
+    await benchmarkDiagnostics(page).stop()
+    const editor = page.locator('[data-component="new-session"] [data-component="composer-editor"]')
+    await expect(editor).toHaveText("")
+    await page.keyboard.type("Draft input")
+    await expect(editor).toHaveText("Draft input")
+    expect(writes).toEqual([])
+    report(
+      {
+        firstCorrectObservedMs: result.summary.all.firstObservedMs,
+        stableObservedMs: result.summary.all.stableObservedMs,
+        ...result,
+      },
+      { entry, data: "fixture", inputEvent: "mousedown" },
+    )
+  })
+}
+
+benchmark("entry: cold session from Home", async ({ page, report }) => {
+  const requests: string[] = []
+  await mockStressTimeline(page, {
+    onMessages: (request) => {
+      if (request.phase === "start") requests.push(request.sessionID)
+    },
+  })
+  await installStressSessionTabs(page, { sessionIDs: [] })
+  await page.goto("/")
+  const selector = `[data-component="home-session-row-container"][data-session-id="${fixture.targetID}"] [data-component="home-session-row"]`
+  await expect(page.locator(selector)).toBeVisible()
+  expect(requests).not.toContain(fixture.targetID)
+  const href = stressSessionHref(fixture.targetID)
+  await benchmarkDiagnostics(page).startTrace()
+  const result = await measureSessionSwitch(page, {
+    destinationIDs: fixture.messages[fixture.targetID].map((message) => message.id),
+    sourceIDs: [],
+    lastID: fixture.expected.targetMessageIDs.at(-1)!,
+    requiredPartID: fixture.expected.targetPartIDs.at(-1)!,
+    href,
+    triggerSelector: selector,
+    switch: async () => {
+      await page.locator(selector).click()
+      await waitForStableTimeline(page, fixture.expected.targetMessageIDs.at(-1)!)
+    },
+  })
+  await benchmarkDiagnostics(page).stop()
+  await expect(
+    page.locator(`[data-titlebar-tab-slot][data-active="true"] [data-titlebar-tab-link][href="${href}"]`),
+  ).toHaveCount(1)
+  expect(requests).toContain(fixture.targetID)
+  report(result, { entry: "home", data: "cold paginated fixture", inputEvent: "mousedown" })
+})

packages/app/e2e/performance/timeline/session-tab-switch-benchmark.spec.ts

@@ -1,71 +1,129 @@
 import type { Page } from "@playwright/test"
+import { mockOpenCodeServer } from "../../utils/mock-server"
 import { expectSessionTitle } from "../../utils/waits"
-import { benchmark, expect, withBenchmarkPage } from "../benchmark"
+import { benchmark, benchmarkDiagnostics, expect } from "../benchmark"
 import { fixture } from "./session-timeline-stress.fixture"
+import { expected, messages, workload } from "./session-tab-switch.fixture"
 import {
   createReviewDiffs,
   installStressSessionTabs,
   installTimelineSettings,
-  mockStressTimeline,
   stressSessionHref,
 } from "./timeline-test-helpers"
 import { measureSessionSwitch, waitForStableTimeline } from "./session-tab-switch-probe"
 
 const scenarios = [
-  { cached: false, review: false, resized: false },
-  { cached: false, review: true, resized: false },
-  { cached: true, review: false, resized: false },
-  { cached: true, review: true, resized: false },
-  { cached: true, review: true, resized: true },
-]
+  { cache: "cold", review: "closed" },
+  { cache: "cold", review: "open" },
+  { cache: "warm", review: "closed" },
+  { cache: "warm", review: "open" },
+  { cache: "warm", review: "resized" },
+] as const
+
+const viewport = { width: 1440, height: 900 }
+const reviewDiffs = createReviewDiffs()
+benchmark.use({ viewport, video: "off", trace: "off", serviceWorkers: "block", traceScope: "interaction" })
 
 scenarios.forEach((scenario) => {
-  const name = `tab switch: ${scenario.cached ? "cached" : "unmounted"}, review ${scenario.review ? "open" : "closed"}${scenario.resized ? ", resized" : ""}`
-  benchmark(name, async ({ browser, report }, testInfo) => {
-    const result = await withBenchmarkPage(
-      browser,
-      name,
-      async (page) => {
-        await mockStressTimeline(page, { vcsDiff: createReviewDiffs() })
-        await installTimelineSettings(page)
-        await installStressSessionTabs(page)
-        await page.goto(stressSessionHref(fixture.sourceID))
-        await expectSessionTitle(page, fixture.expected.sourceTitle)
-        await waitForStableTimeline(page, fixture.expected.sourceMessageIDs.at(-1)!)
-        if (scenario.review && !scenario.resized) await openReviewPane(page)
-        if (scenario.cached) {
-          await switchSession(page, fixture.targetID, fixture.expected.targetTitle)
-          const answer = page.locator(`[data-timeline-part-id="${fixture.expected.targetPartIDs.at(-1)}"]`)
-          await expect(answer.locator('[data-component="markdown"]')).toHaveAttribute("data-markdown-ready", "")
-          await expect
-            .poll(() =>
-              answer.evaluate((element) => element.checkVisibility({ checkOpacity: true, checkVisibilityCSS: true })),
-            )
-            .toBe(true)
-          await waitForStableTimeline(page, fixture.expected.targetMessageIDs.at(-1)!)
-          await switchSession(page, fixture.sourceID, fixture.expected.sourceTitle)
-        }
-        if (scenario.resized) await openReviewPane(page)
-        await waitForStableTimeline(page, fixture.expected.sourceMessageIDs.at(-1)!)
+  benchmark(`tab switch: ${scenario.cache}, review ${scenario.review}`, async ({ page, report }, testInfo) => {
+    const requests = await prepareSessionTabs(page)
+    if (scenario.review === "open") await openReviewPane(page)
+    if (scenario.cache === "warm") {
+      await switchSession(page, fixture.targetID, fixture.expected.targetTitle)
+      await expectReadyTimeline(page, fixture.targetID)
+      await switchSession(page, fixture.sourceID, fixture.expected.sourceTitle)
+    }
+    if (scenario.review === "resized") await openReviewPane(page)
+    await expectReadyTimeline(page, fixture.sourceID)
+    await benchmarkDiagnostics(page).startTrace()
+    const requestsBefore = requests.length
 
-        return measureSessionSwitch(page, {
-          destinationIDs: fixture.messages[fixture.targetID].map((message) => message.id),
-          sourceIDs: fixture.messages[fixture.sourceID].map((message) => message.id),
-          lastID: fixture.expected.targetMessageIDs.at(-1)!,
-          requiredPartID: fixture.expected.targetPartIDs.at(-1),
-          href: stressSessionHref(fixture.targetID),
-          switch: () => switchSession(page, fixture.targetID, fixture.expected.targetTitle),
-        })
+    const result = await measureSessionSwitch(page, {
+      destinationIDs: messages[fixture.targetID].map((message) => message.id),
+      sourceIDs: messages[fixture.sourceID].map((message) => message.id),
+      lastID: expected[fixture.targetID].lastID,
+      requiredPartID: expected[fixture.targetID].answerID,
+      href: stressSessionHref(fixture.targetID),
+      switch: () => switchSession(page, fixture.targetID, fixture.expected.targetTitle),
+    })
+
+    expect(result.firstCorrectObservedMs).not.toBeNull()
+    expect(result.stableObservedMs).not.toBeNull()
+    expect(requests).toHaveLength(requestsBefore)
+    await expectReadyTimeline(page, fixture.targetID)
+    report(
+      {
+        ...result,
+        messageRequestsDuringSwitch: requests.length - requestsBefore,
+        rendererMemory:
+          process.env.OPENCODE_PERFORMANCE_MEMORY === "1" ? await retainedRendererMemory(page) : undefined,
+      },
+      {
+        ...scenario,
+        ...workload,
+        viewport,
+        browserVersion: page.context().browser()!.version(),
+        serviceWorkers: "blocked",
+        reviewFiles: scenario.review === "closed" ? 0 : reviewDiffs.length,
+        data: "prefetched",
+        transport: process.env.OPENCODE_PERFORMANCE_HTTP_FIXTURE === "1" ? "http" : "playwright-route",
+        inputEvent: "mousedown",
+        requireReadyAnswer: true,
       },
-      testInfo,
     )
-    expect(result.unknownSamples).toBe(0)
-    expect(result.wrongDestinationSamples).toBe(0)
-    if (scenario.cached) expect(result.blankSamples).toBe(0)
-    report(result, { ...scenario, inputEvent: "mousedown", requireReadyAnswer: true })
+    if (testInfo.repeatEachIndex === 0) {
+      await page.screenshot({ path: testInfo.outputPath("destination.png") })
+      await testInfo.attach("destination", { path: testInfo.outputPath("destination.png"), contentType: "image/png" })
+    }
   })
 })
 
+async function prepareSessionTabs(page: Page) {
+  const requests: string[] = []
+  page.on("request", (request) => {
+    if (request.method() !== "GET") return
+    const match = new URL(request.url()).pathname.match(/^\/api\/session\/([^/]+)\/message$/)
+    if (match) requests.push(decodeURIComponent(match[1]))
+  })
+  if (process.env.OPENCODE_PERFORMANCE_HTTP_FIXTURE !== "1")
+    await mockOpenCodeServer(page, {
+      sessions: fixture.sessions,
+      provider: fixture.provider,
+      directory: fixture.directory,
+      project: fixture.project,
+      // Return the full history so every scenario exercises a long loaded timeline.
+      pageMessages: (sessionID) => ({ items: messages[sessionID] ?? [] }),
+      vcsDiff: reviewDiffs,
+    })
+  await installTimelineSettings(page)
+  await installStressSessionTabs(page)
+  // Restored tabs prefetch their data even when their transcript has never rendered.
+  const prefetch = page.waitForResponse((response) =>
+    new URL(response.url()).pathname.endsWith(`/session/${fixture.targetID}/message`),
+  )
+  await page.goto(stressSessionHref(fixture.sourceID))
+  expect(await (await prefetch).finished()).toBeNull()
+  await expectSessionTitle(page, fixture.expected.sourceTitle)
+  await expectReadyTimeline(page, fixture.sourceID)
+  await expect(page.locator(`[data-timeline-part-id="${expected[fixture.targetID].answerID}"]`)).toHaveCount(0)
+  expect(requests.toSorted()).toEqual([fixture.sourceID, fixture.targetID].toSorted())
+  return requests
+}
+
+async function expectReadyTimeline(page: Page, sessionID: string) {
+  const answer = page.locator(`[data-timeline-part-id="${expected[sessionID].answerID}"]`)
+  await expect(answer.locator('[data-component="markdown"]')).toHaveAttribute("data-markdown-ready", "")
+  await expect(answer.getByRole("table")).toHaveCount(1)
+  await expect(answer.locator("pre")).toHaveCount(4)
+  await expect
+    .poll(() => answer.evaluate((element) => element.checkVisibility({ checkOpacity: true, checkVisibilityCSS: true })))
+    .toBe(true)
+  await waitForStableTimeline(page, expected[sessionID].lastID)
+  await expect(page.locator('[data-timeline-key] [data-component="markdown"]:not([data-markdown-ready])')).toHaveCount(
+    0,
+  )
+}
+
 async function switchSession(page: Page, sessionID: string, title: string) {
   const tab = page.locator(`[data-slot="titlebar-tabs"] a[href="${stressSessionHref(sessionID)}"]`)
   await expect(tab).toHaveCount(1)
@@ -80,4 +138,20 @@ async function openReviewPane(page: Page) {
     const text = document.querySelector("#review-panel")?.textContent ?? ""
     return text.includes("generated-000.ts") && text.includes("+3")
   })
+  await page.locator('[data-slot="session-chat-panel"]').evaluate(async (panel) => {
+    await Promise.all(panel.getAnimations().map((animation) => animation.finished))
+  })
+}
+
+async function retainedRendererMemory(page: Page) {
+  const cdp = await page.context().newCDPSession(page)
+  try {
+    await cdp.send("HeapProfiler.collectGarbage")
+    return {
+      heap: await cdp.send("Runtime.getHeapUsage"),
+      dom: await cdp.send("Memory.getDOMCounters"),
+    }
+  } finally {
+    await cdp.detach()
+  }
 }

packages/app/e2e/performance/timeline/session-tab-switch-probe.spec.ts

@@ -2,66 +2,77 @@ import { benchmark, expect } from "../benchmark"
 import { measureSessionSwitch } from "./session-tab-switch-probe"
 import type { SessionSwitchSample } from "./session-tab-switch-metrics"
 
-benchmark("starts at mousedown and excludes hidden or unfinished destination content", async ({ page, report }) => {
-  await page.setContent(`
-    <a href="/session/destination">Destination</a>
+for (const tag of ["a", "button"] as const) {
+  benchmark(
+    `starts at ${tag} mousedown and excludes hidden or unfinished destination content`,
+    async ({ page, report }) => {
+      await page.setContent(`
+    <${tag} id="destination" ${tag === "a" ? 'href="/session/destination"' : 'type="button"'}>Destination</${tag}>
     <div class="scroll-view__viewport" style="height:200px;overflow:auto">
       <div data-timeline-row="message" data-timeline-key="row" data-message-id="source">
         <div data-timeline-part-id="answer"><div data-component="markdown">Destination answer</div></div>
       </div>
     </div>
   `)
-  await page.evaluate(() => {
-    document.querySelector("a")!.addEventListener("mousedown", () => {
-      const row = document.querySelector<HTMLElement>("[data-message-id]")!
-      row.dataset.messageId = "destination"
-      row.style.visibility = "hidden"
-    })
-  })
-  const result = await measureSessionSwitch(page, {
-    destinationIDs: ["destination"],
-    sourceIDs: ["source"],
-    lastID: "destination",
-    requiredPartID: "answer",
-    requireBottomAnchor: false,
-    href: "/session/destination",
-    switch: async () => {
-      // No click is dispatched: the probe must observe the event that activates tabs.
-      await page.getByRole("link", { name: "Destination" }).dispatchEvent("mousedown", { button: 0 })
-      await page.waitForFunction(() => {
-        const host = window as Window & { __sessionSwitchProbe?: { samples: SessionSwitchSample[] } }
-        return host.__sessionSwitchProbe?.samples.some((sample) => !sample.hasVisibleRows)
+      await page.evaluate(() => {
+        document.querySelector("#destination")!.addEventListener("mousedown", () => {
+          const row = document.querySelector<HTMLElement>("[data-message-id]")!
+          row.dataset.messageId = "destination"
+          row.style.visibility = "hidden"
+        })
       })
-      await page.locator("[data-message-id]").evaluate((row) => row.style.removeProperty("visibility"))
-      await page.waitForFunction(() => {
-        const host = window as Window & { __sessionSwitchProbe?: { samples: SessionSwitchSample[] } }
-        return host.__sessionSwitchProbe?.samples.some(
-          (sample) => sample.destination.length > 0 && sample.requiredPartVisible === false,
-        )
-      })
-      const beforeClip = await page.evaluate(() => {
-        const row = document.querySelector<HTMLElement>("[data-timeline-key]")!
-        row.style.cssText = "height:10px;position:relative;overflow:clip"
-        const answer = row.querySelector<HTMLElement>("[data-timeline-part-id]")!
-        answer.style.cssText = "position:absolute;top:30px;width:150px"
-        answer.querySelector('[data-component="markdown"]')!.setAttribute("data-markdown-ready", "")
-        return (
-          (window as Window & { __sessionSwitchProbe?: { samples: SessionSwitchSample[] } }).__sessionSwitchProbe
-            ?.samples.length ?? 0
-        )
-      })
-      await page.waitForFunction((count) => {
-        const host = window as Window & { __sessionSwitchProbe?: { samples: SessionSwitchSample[] } }
-        return host.__sessionSwitchProbe?.samples.slice(count).some((sample) => sample.requiredPartVisible === false)
-      }, beforeClip)
-      await page.locator("[data-timeline-key]").evaluate((row) => {
-        row.style.height = "100px"
+      const result = await measureSessionSwitch(page, {
+        destinationIDs: ["destination"],
+        sourceIDs: ["source"],
+        lastID: "destination",
+        requiredPartID: "answer",
+        requireBottomAnchor: false,
+        href: "/session/destination",
+        triggerSelector: tag === "button" ? "#destination" : undefined,
+        switch: async () => {
+          // No click is dispatched: the probe must observe the event that activates tabs.
+          await page
+            .getByRole(tag === "a" ? "link" : "button", { name: "Destination", exact: true })
+            .dispatchEvent("mousedown", { button: 0 })
+          await page.waitForFunction(() => {
+            const host = window as Window & { __sessionSwitchProbe?: { samples: SessionSwitchSample[] } }
+            return host.__sessionSwitchProbe?.samples.some((sample) => !sample.hasVisibleRows)
+          })
+          await page.locator("[data-message-id]").evaluate((row) => row.style.removeProperty("visibility"))
+          await page.waitForFunction(() => {
+            const host = window as Window & { __sessionSwitchProbe?: { samples: SessionSwitchSample[] } }
+            return host.__sessionSwitchProbe?.samples.some(
+              (sample) => sample.destination.length > 0 && sample.requiredPartVisible === false,
+            )
+          })
+          const beforeClip = await page.evaluate(() => {
+            const row = document.querySelector<HTMLElement>("[data-timeline-key]")!
+            row.style.cssText = "height:10px;position:relative;overflow:clip"
+            const answer = row.querySelector<HTMLElement>("[data-timeline-part-id]")!
+            answer.style.cssText = "position:absolute;top:30px;width:150px"
+            answer.querySelector('[data-component="markdown"]')!.setAttribute("data-markdown-ready", "")
+            return (
+              (window as Window & { __sessionSwitchProbe?: { samples: SessionSwitchSample[] } }).__sessionSwitchProbe
+                ?.samples.length ?? 0
+            )
+          })
+          await page.waitForFunction((count) => {
+            const host = window as Window & { __sessionSwitchProbe?: { samples: SessionSwitchSample[] } }
+            return host.__sessionSwitchProbe?.samples
+              .slice(count)
+              .some((sample) => sample.requiredPartVisible === false)
+          }, beforeClip)
+          await page.locator("[data-timeline-key]").evaluate((row) => {
+            row.style.height = "100px"
+          })
+        },
       })
+      expect(result.blankSamples).toBeGreaterThan(0)
+      expect(result.firstCorrectObservedMs).not.toBeNull()
+      expect(result.stableObservedMs).not.toBeNull()
+      expect(result.firstCorrectObservedMs).toBeGreaterThan(result.firstDestinationObservedMs!)
+      expect(await page.evaluate(() => "__sessionSwitchProbe" in window)).toBe(false)
+      report(result)
     },
-  })
-  expect(result.blankSamples).toBeGreaterThan(0)
-  expect(result.firstCorrectObservedMs).not.toBeNull()
-  expect(result.stableObservedMs).not.toBeNull()
-  expect(result.firstCorrectObservedMs).toBeGreaterThan(result.firstDestinationObservedMs!)
-  report(result)
-})
+  )
+}

packages/app/e2e/performance/timeline/session-tab-switch-probe.ts

@@ -14,124 +14,132 @@ async function installSessionSwitchProbe(
     lastID: string
     requiredPartID?: string
     requireBottomAnchor?: boolean
+    triggerSelector?: string
     href: string
   },
 ) {
-  await page.evaluate(({ destinationIDs, sourceIDs, lastID, requiredPartID, requireBottomAnchor, href }) => {
-    const destination = new Set(destinationIDs)
-    const source = new Set(sourceIDs)
-    const samples: SessionSwitchSample[] = []
-    let started: number | undefined
-    let running = true
-    const reviewLevels: Record<string, string> = {
-      panel: "#review-panel",
-      tabs: '#review-panel [data-component="tabs"]',
-      body: '#review-panel [data-slot="session-review-v2-body"]',
-      review: '#review-panel [data-component="session-review-v2"]',
-      preview: '#review-panel [data-slot="session-review-v2-preview"]',
-      scroll: '#review-panel [data-slot="session-review-v2-diff-scroll"]',
-      file: '#review-panel [data-component="file"][data-mode="diff"]',
-    }
-    const initialReviewNodes: Record<string, Element | null> = {}
-    const sample = () => {
-      if (!running || started === undefined) return
-      setTimeout(() => {
+  await page.evaluate(
+    ({ destinationIDs, sourceIDs, lastID, requiredPartID, requireBottomAnchor, triggerSelector, href }) => {
+      const destination = new Set(destinationIDs)
+      const source = new Set(sourceIDs)
+      const samples: SessionSwitchSample[] = []
+      let started: number | undefined
+      let running = true
+      const reviewLevels: Record<string, string> = {
+        panel: "#review-panel",
+        tabs: '#review-panel [data-component="tabs"]',
+        body: '#review-panel [data-slot="session-review-v2-body"]',
+        review: '#review-panel [data-component="session-review-v2"]',
+        preview: '#review-panel [data-slot="session-review-v2-preview"]',
+        scroll: '#review-panel [data-slot="session-review-v2-diff-scroll"]',
+        file: '#review-panel [data-component="file"][data-mode="diff"]',
+      }
+      const initialReviewNodes: Record<string, Element | null> = {}
+      const sample = () => {
         if (!running || started === undefined) return
-        const reviewPanel = document.querySelector<HTMLElement>("#review-panel")
-        const reviewFile = reviewPanel?.querySelector('[data-component="file"][data-mode="diff"]')
-        const initialReviewFile = initialReviewNodes.file
-        const replacedLevels = Object.entries(reviewLevels).flatMap(([name, selector]) => {
-          const initial = initialReviewNodes[name]
-          if (!initial) return []
-          const current = document.querySelector(selector)
-          return current && current !== initial ? [name] : []
-        })
-        const review = reviewPanel
-          ? {
-              fileHost: !!reviewFile,
-              fileHostReplaced: !!initialReviewFile && !!reviewFile && reviewFile !== initialReviewFile,
-              header:
-                reviewPanel
-                  .querySelector<HTMLElement>('[data-slot="session-review-v2-file-header"]')
-                  ?.textContent?.trim() ?? "",
-              replacedLevels,
-            }
-          : undefined
-        const root = [...document.querySelectorAll<HTMLElement>(".scroll-view__viewport")].find((element) =>
-          element.querySelector("[data-timeline-row]"),
-        )
-        if (root) {
-          const view = root.getBoundingClientRect()
-          const inViewport = (element: HTMLElement) => {
-            if (!element.checkVisibility({ checkOpacity: true, checkVisibilityCSS: true })) return false
-            const rect = element.getBoundingClientRect()
-            const clip = element.closest<HTMLElement>("[data-timeline-key]")?.getBoundingClientRect() ?? view
-            return (
-              Math.min(rect.bottom, clip.bottom, view.bottom) > Math.max(rect.top, clip.top, view.top) &&
-              Math.min(rect.right, clip.right, view.right) > Math.max(rect.left, clip.left, view.left)
-            )
-          }
-          const visible = [...root.querySelectorAll<HTMLElement>("[data-message-id]")]
-            .filter(inViewport)
-            .map((element) => element.dataset.messageId!)
-          const hasVisibleRows = [...root.querySelectorAll<HTMLElement>("[data-timeline-key]")].some(inViewport)
-          const requiredPartVisible = requiredPartID
-            ? [...root.querySelectorAll<HTMLElement>("[data-timeline-part-id]")].some((element) => {
-                if (element.dataset.timelinePartId !== requiredPartID) return false
-                if (!element.textContent?.trim()) return false
-                if (element.querySelector('[data-component="markdown"]:not([data-markdown-ready])')) return false
-                return inViewport(element)
-              })
+        setTimeout(() => {
+          if (!running || started === undefined) return
+          const reviewPanel = document.querySelector<HTMLElement>("#review-panel")
+          const reviewFile = reviewPanel?.querySelector('[data-component="file"][data-mode="diff"]')
+          const initialReviewFile = initialReviewNodes.file
+          const replacedLevels = Object.entries(reviewLevels).flatMap(([name, selector]) => {
+            const initial = initialReviewNodes[name]
+            if (!initial) return []
+            const current = document.querySelector(selector)
+            return current && current !== initial ? [name] : []
+          })
+          const review = reviewPanel
+            ? {
+                fileHost: !!reviewFile,
+                fileHostReplaced: !!initialReviewFile && !!reviewFile && reviewFile !== initialReviewFile,
+                header:
+                  reviewPanel
+                    .querySelector<HTMLElement>('[data-slot="session-review-v2-file-header"]')
+                    ?.textContent?.trim() ?? "",
+                replacedLevels,
+              }
             : undefined
-          const spacer = root.querySelector<HTMLElement>('[data-timeline-row="bottom-spacer"]')?.getBoundingClientRect()
-          samples.push({
-            observedAtMs: performance.now() - started,
-            destination: visible.filter((id) => destination.has(id)),
-            source: visible.filter((id) => source.has(id)),
-            hasVisibleRows,
-            last: visible.includes(lastID),
-            requiredPartVisible,
-            bottomAnchorRequired: requireBottomAnchor !== false,
-            bottomErrorPx: spacer ? spacer.bottom - view.bottom : undefined,
-            review,
-          })
-        } else {
-          samples.push({
-            observedAtMs: performance.now() - started,
-            destination: [],
-            source: [],
-            hasVisibleRows: false,
-            last: false,
-            requiredPartVisible: requiredPartID ? false : undefined,
-            bottomAnchorRequired: requireBottomAnchor !== false,
-            review,
-          })
+          const root = [...document.querySelectorAll<HTMLElement>(".scroll-view__viewport")].find((element) =>
+            element.querySelector("[data-timeline-row]"),
+          )
+          if (root) {
+            const view = root.getBoundingClientRect()
+            const inViewport = (element: HTMLElement) => {
+              if (!element.checkVisibility({ checkOpacity: true, checkVisibilityCSS: true })) return false
+              const rect = element.getBoundingClientRect()
+              const clip = element.closest<HTMLElement>("[data-timeline-key]")?.getBoundingClientRect() ?? view
+              return (
+                Math.min(rect.bottom, clip.bottom, view.bottom) > Math.max(rect.top, clip.top, view.top) &&
+                Math.min(rect.right, clip.right, view.right) > Math.max(rect.left, clip.left, view.left)
+              )
+            }
+            const visible = [...root.querySelectorAll<HTMLElement>("[data-message-id]")]
+              .filter(inViewport)
+              .map((element) => element.dataset.messageId!)
+            const hasVisibleRows = [...root.querySelectorAll<HTMLElement>("[data-timeline-key]")].some(inViewport)
+            const requiredPartVisible = requiredPartID
+              ? [...root.querySelectorAll<HTMLElement>("[data-timeline-part-id]")].some((element) => {
+                  if (element.dataset.timelinePartId !== requiredPartID) return false
+                  if (!element.textContent?.trim()) return false
+                  if (element.querySelector('[data-component="markdown"]:not([data-markdown-ready])')) return false
+                  return inViewport(element)
+                })
+              : undefined
+            const spacer = root
+              .querySelector<HTMLElement>('[data-timeline-row="bottom-spacer"]')
+              ?.getBoundingClientRect()
+            samples.push({
+              observedAtMs: performance.now() - started,
+              destination: visible.filter((id) => destination.has(id)),
+              source: visible.filter((id) => source.has(id)),
+              hasVisibleRows,
+              last: visible.includes(lastID),
+              requiredPartVisible,
+              bottomAnchorRequired: requireBottomAnchor !== false,
+              bottomErrorPx: spacer ? spacer.bottom - view.bottom : undefined,
+              review,
+            })
+          } else {
+            samples.push({
+              observedAtMs: performance.now() - started,
+              destination: [],
+              source: [],
+              hasVisibleRows: false,
+              last: false,
+              requiredPartVisible: requiredPartID ? false : undefined,
+              bottomAnchorRequired: requireBottomAnchor !== false,
+              review,
+            })
+          }
+          requestAnimationFrame(sample)
+        }, 0)
+      }
+      const start = (event: MouseEvent) => {
+        if (started !== undefined || event.button !== 0) return
+        const trigger = event.target instanceof Element ? event.target.closest(triggerSelector ?? "a") : undefined
+        if (!trigger || (!triggerSelector && trigger.getAttribute("href") !== href)) return
+        started = performance.now()
+        performance.mark("session-switch:start", { startTime: started })
+        for (const [name, selector] of Object.entries(reviewLevels)) {
+          initialReviewNodes[name] = document.querySelector(selector)
         }
         requestAnimationFrame(sample)
-      }, 0)
-    }
-    const start = (event: MouseEvent) => {
-      if (started !== undefined || event.button !== 0) return
-      const link = event.target instanceof Element ? event.target.closest("a") : undefined
-      if (link?.getAttribute("href") !== href) return
-      started = performance.now()
-      for (const [name, selector] of Object.entries(reviewLevels)) {
-        initialReviewNodes[name] = document.querySelector(selector)
       }
-      requestAnimationFrame(sample)
-    }
-    // Tabs activate on mousedown; click alone misses the synchronous navigation work.
-    document.addEventListener("mousedown", start, true)
-    document.addEventListener("click", start, true)
-    ;(window as Window & { __sessionSwitchProbe?: SessionSwitchProbe }).__sessionSwitchProbe = {
-      samples,
-      stop: () => {
-        running = false
-        document.removeEventListener("mousedown", start, true)
-        document.removeEventListener("click", start, true)
-      },
-    }
-  }, input)
+      // Tabs activate on mousedown; click alone misses the synchronous navigation work.
+      document.addEventListener("mousedown", start, true)
+      document.addEventListener("click", start, true)
+      ;(window as Window & { __sessionSwitchProbe?: SessionSwitchProbe }).__sessionSwitchProbe = {
+        samples,
+        stop: () => {
+          running = false
+          document.removeEventListener("mousedown", start, true)
+          document.removeEventListener("click", start, true)
+          Object.keys(initialReviewNodes).forEach((key) => (initialReviewNodes[key] = null))
+        },
+      }
+    },
+    input,
+  )
 }
 
 async function waitForStableSessionSwitch(page: Page) {
@@ -159,9 +167,17 @@ async function collectSessionSwitchResult(page: Page) {
   const samples = await page.evaluate(() => {
     const probe = (window as Window & { __sessionSwitchProbe?: SessionSwitchProbe }).__sessionSwitchProbe!
     probe.stop()
+    delete (window as Window & { __sessionSwitchProbe?: SessionSwitchProbe }).__sessionSwitchProbe
     return probe.samples
   })
-  return classifySessionSwitch(samples)
+  const result = classifySessionSwitch(samples)
+  await page.evaluate(({ firstCorrectObservedMs, stableObservedMs }) => {
+    const start = performance.getEntriesByName("session-switch:start").at(-1)!.startTime
+    if (firstCorrectObservedMs !== null)
+      performance.mark("session-switch:ready", { startTime: start + firstCorrectObservedMs })
+    if (stableObservedMs !== null) performance.mark("session-switch:stable", { startTime: start + stableObservedMs })
+  }, result)
+  return result
 }
 
 export async function measureSessionSwitch(
@@ -172,6 +188,7 @@ export async function measureSessionSwitch(
     lastID: string
     requiredPartID?: string
     requireBottomAnchor?: boolean
+    triggerSelector?: string
     href: string
     switch: () => Promise<void>
   },
@@ -185,6 +202,7 @@ export async function measureSessionSwitch(
   } finally {
     await page.evaluate(() => {
       ;(window as Window & { __sessionSwitchProbe?: SessionSwitchProbe }).__sessionSwitchProbe?.stop()
+      delete (window as Window & { __sessionSwitchProbe?: SessionSwitchProbe }).__sessionSwitchProbe
     })
   }
 }

packages/app/e2e/performance/timeline/session-tab-switch.fixture.ts

@@ -0,0 +1,143 @@
+import type { SessionMessageInfo } from "@opencode-ai/client/promise"
+import { fixture } from "./session-timeline-stress.fixture"
+
+export const exchanges = 200
+
+export const messages: Record<string, SessionMessageInfo[]> = Object.fromEntries(
+  [fixture.sourceID, fixture.targetID].map((sessionID) => [
+    sessionID,
+    Array.from({ length: exchanges }, (_, index) => {
+      const seed = fixture.messages[fixture.targetID]
+      const user = seed[(index % (seed.length / 2)) * 2]!
+      const assistant = seed[(index % (seed.length / 2)) * 2 + 1]!
+      if (user.type !== "user" || assistant.type !== "assistant") throw new Error("Expected a user/assistant pair")
+      const suffix = `${sessionID}_${String(index).padStart(4, "0")}`
+      return [
+        {
+          ...user,
+          id: `msg_user_${suffix}`,
+          time: { created: 1700000000000 + index * 10_000 },
+        },
+        {
+          ...assistant,
+          id: `msg_assistant_${suffix}`,
+          time: { created: 1700000001000 + index * 10_000, completed: 1700000008000 + index * 10_000 },
+          content: [
+            ...assistant.content
+              .filter((part) => part.type !== "text")
+              .map((part) => (part.type === "tool" ? { ...part, id: `${part.id}_${suffix}` } : part)),
+            { type: "text", text: complexMarkdown(sessionID, index) },
+          ],
+        },
+      ] satisfies SessionMessageInfo[]
+    }).flat(),
+  ]),
+)
+
+export const expected = Object.fromEntries(
+  [fixture.sourceID, fixture.targetID].map((sessionID) => [
+    sessionID,
+    {
+      lastID: messages[sessionID].at(-2)!.id,
+      answerID: `${messages[sessionID].at(-1)!.id}:text:0`,
+    },
+  ]),
+)
+
+export const workload = {
+  fixture: "long-complex-markdown-v1",
+  exchangesPerSession: exchanges,
+  messagesPerSession: exchanges * 2,
+  history: "full fixture history in one response",
+  sessions: Object.fromEntries(
+    Object.entries(messages).map(([sessionID, items]) => [
+      sessionID,
+      {
+        payloadBytes: Buffer.byteLength(JSON.stringify(items)),
+        markdownBytes: items.reduce(
+          (total, message) =>
+            total +
+            (message.type === "assistant"
+              ? message.content.reduce(
+                  (size, part) => size + (part.type === "text" ? Buffer.byteLength(part.text) : 0),
+                  0,
+                )
+              : 0),
+          0,
+        ),
+      },
+    ]),
+  ),
+}
+
+function complexMarkdown(sessionID: string, index: number) {
+  return `## Renderer review ${sessionID} / ${index}
+
+Preserve **semantic identity**, *measured geometry*, and ~~obsolete estimates~~ when switching sessions. The \`measureElement(node)\` result must agree with the [rendering contract](https://example.com/rendering/${sessionID}/${index}).
+
+> A completed answer contains formatted prose, highlighted source, and structured results.
+> Keep the previous view until the destination is ready, rather than exposing partially formatted content.
+
+### Readiness checklist
+
+- [x] Resolve the destination session and its messages.
+- [x] Parse Markdown and highlight fenced code.
+- [ ] Verify a different panel width.
+  - Preserve the bottom anchor.
+  - Reuse the measured rows when their width matches.
+
+| Stage | Input | Expected result | Verification |
+| :--- | ---: | :--- | :--- |
+${Array.from({ length: 8 }, (_, row) => `| stage-${index}-${row} | ${index * 8 + row} | **ready** with \`row[${row}]\` | stable geometry and visible content |`).join("\n")}
+
+### Implementation
+
+\`\`\`tsx
+import { For, Show, createMemo } from "solid-js"
+
+type Row = { id: string; title: string; ready: boolean; height: number }
+
+export function SessionRows${index}(props: { rows: Row[]; selected: string }) {
+  const visible = createMemo(() => props.rows.filter((row) => row.ready))
+  return (
+    <section aria-label="${sessionID}-${index}">
+      <For each={visible()}>{(row) => (
+        <article data-selected={row.id === props.selected}>
+          <h3>{row.title}</h3>
+          <Show when={row.height > 0} fallback={<span>Measuring</span>}>
+            <output>{row.height.toFixed(2)} pixels</output>
+          </Show>
+        </article>
+      )}</For>
+    </section>
+  )
+}
+\`\`\`
+
+\`\`\`json
+${JSON.stringify({ session: sessionID, exchange: index, stages: ["hydrate", "parse", "highlight", "measure"], viewport: { width: 1440, height: 900 }, cache: { markdown: true, geometry: true } }, null, 2)}
+\`\`\`
+
+\`\`\`sql
+SELECT session_id, COUNT(*) AS messages, MAX(created_at) AS latest
+FROM session_message
+WHERE session_id = '${sessionID}' AND ordinal >= ${index}
+GROUP BY session_id
+ORDER BY latest DESC;
+\`\`\`
+
+### Verification
+
+1. Open the long source session and wait for its final answer.
+2. Select the destination tab, without changing the viewport.
+3. Confirm that **all Markdown is ready** and the bottom anchor is correct.
+
+\`\`\`bash
+bun typecheck
+bunx playwright test --config e2e/performance/playwright.config.ts
+git diff --check # ${sessionID}-${index}
+\`\`\`
+
+**Review complete: ${sessionID} / ${index}.**
+`
+}

packages/app/e2e/performance/unit/tab-switch-reporter.test.ts

@@ -0,0 +1,114 @@
+import { expect, spyOn, test } from "bun:test"
+import type { FullConfig, Suite, TestCase, TestResult } from "@playwright/test/reporter"
+import { mkdtemp, readFile, rm } from "node:fs/promises"
+import os from "node:os"
+import path from "node:path"
+import TabSwitchReporter from "../tab-switch-reporter"
+
+test("summarizes each scenario and saves complete records in the configured output directory", async () => {
+  const root = await mkdtemp(path.join(os.tmpdir(), "tab-switch-reporter-"))
+  const output = path.join(root, "configured-output")
+  const log = spyOn(console, "log").mockImplementation(() => {})
+  try {
+    const reporter = new TabSwitchReporter()
+    const cases = Array.from(
+      { length: 23 },
+      (_, index) => ({ id: String(index), title: index < 20 ? "cold" : "warm" }) as TestCase,
+    )
+    const records = cases.map((_, index) => {
+      const first = index < 20 ? 20 - index : [40, 0, 20][index - 20]
+      return JSON.stringify({
+        status: "passed",
+        metrics: {
+          firstCorrectObservedMs: first,
+          stableObservedMs: first * 2,
+          samples: [{ observedAtMs: first, destination: ["answer"], source: [] }],
+        },
+        extra: { preserved: "\u03b1" },
+      })
+    })
+    reporter.onBegin({ projects: [{ outputDir: output }] } as FullConfig, { allTests: () => cases } as Suite)
+    cases.forEach((item, index) => {
+      const bytes = Buffer.from(`BENCHMARK ${records[index]}\r\n`)
+      const split = bytes.indexOf(Buffer.from("\u03b1")) + 1
+      reporter.onTestEnd(item, {
+        status: "passed",
+        stdout:
+          index === 0
+            ? [bytes.subarray(0, split), bytes.subarray(split)]
+            : ["other output\nBENCHMARK_PAGE {}\nBENCH", "MARK ", records[index], "\n"],
+      } as TestResult)
+    })
+    await reporter.onEnd({ status: "passed", startTime: new Date(0), duration: 0 })
+
+    expect(await readFile(path.join(output, "tab-switch-benchmark.jsonl"), "utf8")).toBe(`${records.join("\n")}\n`)
+    const summary = log.mock.calls.map((call) => call.join(" ")).join("\n")
+    expect(summary).toContain("cold\n  Tests: passed=20; unrun=0")
+    expect(summary).toContain("warm\n  Tests: passed=3; unrun=0")
+    expect(summary).toContain("firstCorrectObservedMs: n=20, median=10.50 ms, p95=19.00 ms")
+    expect(summary).toContain("stableObservedMs: n=20, median=21.00 ms, p95=38.00 ms")
+    expect(summary).toContain("firstCorrectObservedMs: n=3, median=20.00 ms, p95=40.00 ms")
+    expect(summary).toContain("stableObservedMs: n=3, median=40.00 ms, p95=80.00 ms")
+  } finally {
+    log.mockRestore()
+    await rm(root, { recursive: true, force: true })
+  }
+})
+
+test("reports failures, missing records, and invalid metrics without discarding raw data", async () => {
+  const output = await mkdtemp(path.join(os.tmpdir(), "tab-switch-reporter-"))
+  const log = spyOn(console, "log").mockImplementation(() => {})
+  try {
+    const reporter = new TabSwitchReporter()
+    const entries = [
+      {
+        status: "passed",
+        raw: '{"status":"passed","metrics":{"firstCorrectObservedMs":12,"stableObservedMs":24}}',
+      },
+      {
+        status: "failed",
+        raw: '{"status":"passed","metrics":{"firstCorrectObservedMs":900,"stableObservedMs":950}}',
+      },
+      {
+        status: "passed",
+        raw: '{"status":"failed","metrics":{"firstCorrectObservedMs":900,"stableObservedMs":950}}',
+      },
+      { status: "timedOut", raw: '{"status":"failed","metrics":null,"error":"Benchmark did not report metrics"}' },
+      {
+        status: "passed",
+        raw: '{"status":"passed","metrics":{"firstCorrectObservedMs":null,"stableObservedMs":40}}',
+      },
+      { status: "failed", raw: '{"status":' },
+      { status: "skipped", raw: undefined },
+    ] as const
+    const cases = Array.from(
+      { length: entries.length + 2 },
+      (_, index) => ({ id: String(index), title: index <= entries.length ? "cold" : "empty" }) as TestCase,
+    )
+    reporter.onBegin({ projects: [{ outputDir: output }] } as FullConfig, { allTests: () => cases } as Suite)
+    entries.forEach((entry, index) => {
+      reporter.onTestEnd(cases[index], {
+        status: entry.status,
+        stdout: entry.raw === undefined ? [] : [`BENCHMARK ${entry.raw}\n`],
+      } as TestResult)
+    })
+    await reporter.onEnd({ status: "interrupted", startTime: new Date(0), duration: 0 })
+
+    expect(await readFile(path.join(output, "tab-switch-benchmark.jsonl"), "utf8")).toBe(
+      entries.flatMap((entry) => (entry.raw === undefined ? [] : [`${entry.raw}\n`])).join(""),
+    )
+    const summary = log.mock.calls.map((call) => call.join(" ")).join("\n")
+    expect(summary).toContain("Tab-switch benchmark: interrupted")
+    expect(summary).toContain("Tests: passed=3, failed=2, timedOut=1, skipped=1; unrun=1")
+    expect(summary).toContain("Records: passed=3, failed=2, invalid JSON=1; missing=2; excluded=5; invalid metrics=1")
+    expect(summary).toContain("firstCorrectObservedMs: n=1, median=12.00 ms, p95=12.00 ms")
+    expect(summary).toContain("stableObservedMs: n=1, median=24.00 ms, p95=24.00 ms")
+    expect(summary).toContain("empty\n  Tests: none; unrun=1")
+    expect(summary).toContain("Records: none; missing=1; excluded=0; invalid metrics=0")
+    expect(summary).toContain("firstCorrectObservedMs: n=0, median=n/a, p95=n/a")
+    expect(summary).toContain("stableObservedMs: n=0, median=n/a, p95=n/a")
+  } finally {
+    log.mockRestore()
+    await rm(output, { recursive: true, force: true })
+  }
+})

packages/app/e2e/regression/session-timeline-hydration.spec.ts

@@ -0,0 +1,99 @@
+import type { SessionMessageInfo } from "@opencode-ai/client/promise"
+import { expect, test } from "@playwright/test"
+import { fixture } from "../performance/timeline/session-timeline-stress.fixture"
+import { stressSessionHref } from "../performance/timeline/timeline-test-helpers"
+import { mockOpenCodeServer } from "../utils/mock-server"
+
+test.use({ viewport: { width: 1440, height: 900 }, serviceWorkers: "block" })
+
+for (const window of ["assistant-only", "mixed"] as const) {
+  test(`renders the ${window} latest page before parent hydration and preserves it afterward`, async ({ page }) => {
+    const session = { ...fixture.sessions[0]!, id: `ses_hydration_${window}` }
+    // Both 20-message pages begin with an assistant; only page three supplies its parent.
+    const messages = Array.from({ length: 41 }, (_, index): SessionMessageInfo => {
+      const id = `msg_hydration_${index}`
+      const time = { created: 1700000000000 + index * 1_000 }
+      if (index === 0 || (window === "mixed" && index === 39))
+        return { id, type: "user", time, text: `Prompt ${index}` }
+      return {
+        id,
+        type: "assistant",
+        time: { ...time, completed: time.created + 500 },
+        model: { id: "claude-opus-4-6", providerID: "opencode" },
+        agent: "build",
+        content: [{ type: "text", text: index === 40 ? "## Hydrated tail\n\n**Ready.**" : `Answer ${index}` }],
+      }
+    })
+    const gates = [21, 1].map((index) => ({
+      before: messages[index]!.id,
+      parent: messages[index === 21 ? 1 : 0]!.id,
+      requested: Promise.withResolvers<void>(),
+      release: Promise.withResolvers<void>(),
+    }))
+    const requests: (string | undefined)[] = []
+    await mockOpenCodeServer(page, {
+      ...fixture,
+      sessions: [session],
+      beforeMessagesResponse: async ({ before }) => {
+        requests.push(before)
+        if (!before) return
+        const gate = gates.find((gate) => gate.before === before)
+        if (!gate) throw new Error(`Unexpected older-page boundary: ${before}`)
+        gate.requested.resolve()
+        await gate.release.promise
+      },
+      pageMessages: (_, limit, before) => {
+        expect(limit).toBe(20)
+        const end = before ? messages.findIndex((message) => message.id === before) : messages.length
+        const start = Math.max(0, end - limit)
+        return { items: messages.slice(start, end), cursor: start > 0 ? messages[start]!.id : undefined }
+      },
+    })
+    const tail = page.locator('[data-timeline-part-id="msg_hydration_40:text:0"]')
+    const markdown = tail.locator('[data-component="markdown"]')
+    const content = page.locator("[data-timeline-virtual-content]", { has: tail })
+    const viewport = page.locator(".scroll-view__viewport", { has: tail })
+    const orphan = page.locator('[data-timeline-row="AssistantPart"]', {
+      has: page.locator('[data-timeline-part-id="msg_hydration_38:text:0"]'),
+    })
+    const expectReadyTail = async () => {
+      await expect(content).toHaveCSS("visibility", "visible")
+      await expect(markdown).toHaveAttribute("data-markdown-ready", "")
+      await expect(markdown.getByRole("heading", { name: "Hydrated tail", exact: true })).toBeInViewport({ ratio: 1 })
+      await expect
+        .poll(() =>
+          viewport.evaluate((element) => Math.abs(element.scrollHeight - element.clientHeight - element.scrollTop)),
+        )
+        .toBeLessThanOrEqual(1)
+    }
+
+    try {
+      await page.goto(stressSessionHref(session.id))
+      await gates[0]!.requested.promise
+      // This must pass while the first older response is still held.
+      await expectReadyTail()
+      await expect(orphan).toHaveAttribute("data-message-id", "msg_hydration_21")
+      if (window === "mixed")
+        await expect(
+          page.locator('[data-timeline-row="UserMessage"][data-message-id="msg_hydration_39"]'),
+        ).toBeInViewport()
+      const original = await markdown.elementHandle()
+
+      for (const gate of gates) {
+        await gate.requested.promise
+        gate.release.resolve()
+        // Parent ownership proves the page reached the projection, not just the network.
+        await expect(orphan).toHaveAttribute("data-message-id", gate.parent)
+        await expectReadyTail()
+        expect(await markdown.evaluate((element, original) => element === original, original)).toBe(true)
+      }
+      expect(requests).toEqual([undefined, ...gates.map((gate) => gate.before)])
+      const ids = await content
+        .locator("[data-timeline-part-id]")
+        .evaluateAll((elements) => elements.map((element) => element.getAttribute("data-timeline-part-id")))
+      expect(new Set(ids).size).toBe(ids.length)
+    } finally {
+      gates.forEach((gate) => gate.release.resolve())
+    }
+  })
+}

packages/app/e2e/regression/session-timeline-mount.spec.ts

@@ -0,0 +1,123 @@
+import { expect, test, type Page } from "@playwright/test"
+import type { SessionMessageInfo } from "@opencode-ai/client/promise"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { fixture } from "../performance/timeline/session-timeline-stress.fixture"
+import { expected, messages } from "../performance/timeline/session-tab-switch.fixture"
+import { installTimelineSettings, stressSessionHref } from "../performance/timeline/timeline-test-helpers"
+
+test.use({ viewport: { width: 1440, height: 900 }, serviceWorkers: "block" })
+
+type Reveal = { pending: number; clipped: string[]; bottomError: number; tables: number; codeBlocks: number }
+
+for (const width of [1440, 390]) {
+  test(`reveals measured Markdown after the worker completes at ${width}px`, async ({ page }) => {
+    await page.setViewportSize({ width, height: 900 })
+    const requested = Promise.withResolvers<void>()
+    const release = Promise.withResolvers<void>()
+    await page.route(/markdown\.worker(?:-[^/?]+\.js|\.ts)(?:\?.*)?$/, async (route) => {
+      requested.resolve()
+      await release.promise
+      await route.continue()
+    })
+    await page.addInitScript((partID) => {
+      const observer = new MutationObserver(() => {
+        const answer = document.querySelector<HTMLElement>(`[data-timeline-part-id="${partID}"]`)
+        const content = answer?.closest<HTMLElement>("[data-timeline-virtual-content]")
+        const root = content?.closest<HTMLElement>(".scroll-view__viewport")
+        if (!answer || !content || !root || !content.checkVisibility({ checkVisibilityCSS: true })) return
+        const spacer = content.querySelector('[data-timeline-row="bottom-spacer"]')
+        ;(window as Window & { __coldReveal?: Reveal }).__coldReveal = {
+          pending: content.querySelectorAll('[data-component="markdown"]:not([data-markdown-ready])').length,
+          clipped: [...content.querySelectorAll<HTMLElement>("[data-timeline-key]")].flatMap((row) =>
+            (row.firstElementChild?.getBoundingClientRect().height ?? 0) > row.getBoundingClientRect().height + 1
+              ? [row.dataset.timelineKey!]
+              : [],
+          ),
+          bottomError: (spacer?.getBoundingClientRect().bottom ?? Infinity) - root.getBoundingClientRect().bottom,
+          tables: answer.querySelectorAll("table").length,
+          codeBlocks: answer.querySelectorAll("pre").length,
+        }
+        observer.disconnect()
+      })
+      observer.observe(document, { childList: true, subtree: true, attributes: true, attributeFilter: ["style"] })
+    }, expected[fixture.sourceID].answerID)
+    await mockOpenCodeServer(page, {
+      sessions: fixture.sessions,
+      project: fixture.project,
+      provider: fixture.provider,
+      directory: fixture.directory,
+      pageMessages: () => ({ items: messages[fixture.sourceID] }),
+    })
+    await installTimelineSettings(page)
+    try {
+      await page.goto(stressSessionHref(fixture.sourceID), { waitUntil: "domcontentloaded" })
+      await requested.promise
+      await expect(page.locator("[data-timeline-virtual-content]")).toHaveCSS("visibility", "hidden")
+      release.resolve()
+      await expect(page.locator("[data-timeline-virtual-content]")).toHaveCSS("visibility", "visible")
+      const reveal = await page.evaluate(() => (window as Window & { __coldReveal?: Reveal }).__coldReveal)
+      expect(reveal).toMatchObject({ pending: 0, clipped: [], tables: 1, codeBlocks: 4 })
+      expect(Math.abs(reveal?.bottomError ?? Infinity)).toBeLessThanOrEqual(1)
+    } finally {
+      release.resolve()
+    }
+  })
+}
+
+test("scrolls within a long answer without mounting unrelated history", async ({ page }) => {
+  await openTimeline(page, messages[fixture.sourceID])
+  const answer = page.locator(`[data-timeline-part-id="${expected[fixture.sourceID].answerID}"]`)
+  await expect(answer.locator('[data-component="markdown"]')).toHaveAttribute("data-markdown-ready", "")
+  await expect(answer.getByRole("table")).toHaveCount(1)
+  const scroller = page.locator(".scroll-view__viewport", { has: answer })
+  await expect
+    .poll(() => scroller.evaluate((element) => element.scrollHeight - element.clientHeight - element.scrollTop))
+    .toBeLessThanOrEqual(1)
+  const rows = page.locator("[data-timeline-key]")
+  const keys = await rows.evaluateAll((elements) =>
+    elements.map((element) => element.getAttribute("data-timeline-key")),
+  )
+  const top = await answer.evaluate((element) => element.getBoundingClientRect().top)
+
+  await scroller.hover()
+  await page.mouse.wheel(0, -240)
+
+  await expect.poll(() => answer.evaluate((element) => element.getBoundingClientRect().top)).toBeCloseTo(top + 240, 0)
+  expect(
+    await rows.evaluateAll((elements) => elements.map((element) => element.getAttribute("data-timeline-key"))),
+  ).toEqual(keys)
+  await expect(answer.locator('[data-component="markdown"]')).toHaveAttribute("data-markdown-ready", "")
+})
+
+test("fills a short cold transcript before revealing it", async ({ page }) => {
+  const history = messages[fixture.sourceID].slice(-6).map((message, index) => {
+    if (message.type === "user") return { ...message, text: `Prompt ${index}`, metadata: undefined }
+    if (message.type === "assistant")
+      return { ...message, content: [{ type: "text" as const, text: `**Answer ${index}**` }] }
+    return message
+  })
+  await openTimeline(page, history)
+  for (const message of history) {
+    if (message.type === "user") {
+      await expect(page.locator(`[data-timeline-row="UserMessage"][data-message-id="${message.id}"]`)).toBeInViewport()
+    }
+    if (message.type === "assistant") {
+      const answer = page.locator(`[data-timeline-part-id="${message.id}:text:0"]`)
+      await expect(answer).toBeInViewport()
+      await expect(answer.locator('[data-component="markdown"]')).toHaveAttribute("data-markdown-ready", "")
+    }
+  }
+})
+
+async function openTimeline(page: Page, history: SessionMessageInfo[]) {
+  await mockOpenCodeServer(page, {
+    sessions: fixture.sessions,
+    project: fixture.project,
+    provider: fixture.provider,
+    directory: fixture.directory,
+    pageMessages: () => ({ items: history }),
+  })
+  await installTimelineSettings(page)
+  await page.goto(stressSessionHref(fixture.sourceID))
+  await expect(page.locator("[data-timeline-virtual-content]")).toHaveCSS("visibility", "visible")
+}

packages/app/e2e/regression/tab-navigate-mousedown.spec.ts

@@ -102,6 +102,14 @@ test("cramped tabs only show the close button for the active tab", async ({ page
   await expect(page).toHaveURL(new RegExp(`${hrefB.replace(/[.*+?^${}()|[\]\\]/g, "\\$&")}$`))
   await expect(tabA.locator('[data-slot="tab-close"]')).toBeHidden()
   await expect(tabB.locator('[data-slot="tab-close"]')).toBeVisible()
+
+  for (const direction of ["ltr", "rtl"]) {
+    await page.evaluate((direction) => document.documentElement.setAttribute("dir", direction), direction)
+    await page.setViewportSize({ width: 450, height: 720 })
+    await expect(tabA.locator("[data-titlebar-tab]")).toHaveAttribute("data-title-overflow", "true")
+    await page.setViewportSize({ width: 1280, height: 720 })
+    await expect(tabA.locator("[data-titlebar-tab]")).toHaveAttribute("data-title-overflow", "false")
+  }
 })
 
 test("vertical tabs show project details, resize, and navigate", async ({ page }) => {
@@ -288,11 +296,12 @@ async function mockServer(page: Page) {
     if (currentSessionInfo) return json(route, { data: currentSession(currentSessionInfo) })
     if (sessions.some((item) => url.pathname === `/api/session/${item.id}/message`))
       return json(route, { data: [], cursor: {} })
+    if (sessions.some((item) => url.pathname === `/api/session/${item.id}/inbox`)) return json(route, { data: [] })
     if (["/api/agent", "/api/provider", "/api/model", "/api/command", "/api/reference"].includes(url.pathname))
       return json(route, { location: { directory: sessionA.directory }, data: [] })
     if (url.pathname === "/api/model/default")
       return json(route, { location: { directory: sessionA.directory }, data: null })
-    if (url.pathname === "/api/permission/request" || url.pathname === "/api/question/request")
+    if (url.pathname === "/api/permission/request" || url.pathname === "/api/form/request")
       return json(route, { location: { directory: sessionA.directory }, data: [] })
     if (url.pathname === "/api/mcp") return json(route, { location: { directory: sessionA.directory }, data: [] })
     if (url.pathname === "/api/mcp/resource")

packages/app/e2e/regression/workspace-accent.spec.ts

@@ -20,95 +20,134 @@ const inventory: WorktreeDirectory[] = [
 
 test.use({ serviceWorkers: "block" })
 
-for (const scenario of [
-  { name: "managed Git worktree", directory: workspace, accent: true },
-  { name: "linked Git worktree outside main", directory: "C:/OpenCode/LinkedWorkspace", accent: true },
-  {
-    name: "linked Git worktree on a narrow screen",
-    directory: "C:/OpenCode/LinkedWorkspace",
-    accent: true,
-    viewport: { width: 390, height: 844 },
-  },
-  { name: "main root with Windows case and separators", directory: "c:\\OPENCODE\\workspaceaccent\\", accent: false },
-  { name: "nested main directory", directory: `${root}/packages/app`, accent: false },
-  { name: "nested workspace inside main", directory: `${workspace}/packages/app`, accent: true },
-  {
-    name: "workspace with Windows case and separators",
-    directory: "c:\\opencode\\WORKSPACEACCENT\\.worktrees\\FEATURE\\src\\",
-    accent: true,
-  },
-  { name: "unregistered sibling with the same prefix", directory: `${workspace}-unregistered`, accent: false },
-  { name: "workspace using another strategy", directory: "C:/OpenCode/WorkspaceCopy", accent: true },
-  { name: "registered directory without a strategy", directory: "C:/OpenCode/RegisteredDirectory", accent: true },
-]) {
-  test(`existing session send button: ${scenario.name}`, async ({ page }, testInfo) => {
-    if (scenario.viewport) await page.setViewportSize(scenario.viewport)
-    const view = await openSession(page, scenario.directory)
-    await view.input.fill("Inspect this fixture workspace.")
-    await expect(view.send).toBeEnabled()
+for (const theme of ["light", "dark"] as const) {
+  test.describe(theme, () => {
+    test.beforeEach(async ({ page }) => {
+      await page.addInitScript((theme) => {
+        localStorage.setItem("opencode-theme-id", "oc-2")
+        localStorage.setItem("opencode-color-scheme", theme)
+      }, theme)
+    })
 
-    if (scenario.name === "managed Git worktree") {
-      // Capture before the color assertion so both red and green runs have evidence.
-      const path = testInfo.outputPath("workspace-accent.png")
-      await view.composer.screenshot({ path })
-      await testInfo.attach("workspace-accent", { path, contentType: "image/png" })
+    for (const scenario of [
+      { name: "managed Git worktree", directory: workspace, accent: true },
+      { name: "linked Git worktree outside main", directory: "C:/OpenCode/LinkedWorkspace", accent: true },
+      {
+        name: "linked Git worktree on a narrow screen",
+        directory: "C:/OpenCode/LinkedWorkspace",
+        accent: true,
+        viewport: { width: 390, height: 844 },
+      },
+      {
+        name: "main root with Windows case and separators",
+        directory: "c:\\OPENCODE\\workspaceaccent\\",
+        accent: false,
+      },
+      { name: "nested main directory", directory: `${root}/packages/app`, accent: false },
+      { name: "nested workspace inside main", directory: `${workspace}/packages/app`, accent: true },
+      {
+        name: "workspace with Windows case and separators",
+        directory: "c:\\opencode\\WORKSPACEACCENT\\.worktrees\\FEATURE\\src\\",
+        accent: true,
+      },
+      { name: "unregistered sibling with the same prefix", directory: `${workspace}-unregistered`, accent: false },
+      { name: "workspace using another strategy", directory: "C:/OpenCode/WorkspaceCopy", accent: true },
+      { name: "registered directory without a strategy", directory: "C:/OpenCode/RegisteredDirectory", accent: true },
+    ]) {
+      test(`existing session send button: ${scenario.name}`, async ({ page }, testInfo) => {
+        if (scenario.viewport) await page.setViewportSize(scenario.viewport)
+        const view = await openSession(page, scenario.directory)
+        await view.input.fill("Inspect this fixture workspace.")
+        await expect(view.send).toBeEnabled()
+
+        if (scenario.name === "managed Git worktree") {
+          // Capture before the color assertion so both red and green runs have evidence.
+          const path = testInfo.outputPath("workspace-accent.png")
+          await view.composer.screenshot({ path })
+          await testInfo.attach("workspace-accent", { path, contentType: "image/png" })
+        }
+
+        await expectBackground(view.send, "contrast")
+        await view.send.hover()
+        await expectBackground(view.send, "contrast")
+        await view.composer.locator('[data-action="composer-model"]').press("Tab")
+        await expect(view.send).toBeFocused()
+        await expectBackground(view.send, "contrast")
+        const message = page.locator('[data-slot="user-message-text"]')
+        await expect(message).toHaveText("Check this fixture workspace.")
+        await expectBackground(
+          message,
+          scenario.accent ? "accent" : theme === "light" ? "layer-02" : "layer-01",
+          "background-color",
+        )
+      })
     }
 
-    await expectBackground(view.send, scenario.accent ? "accent" : "contrast")
-    const message = page.locator('[data-slot="user-message-text"]')
-    await expect(message).toHaveText("Check this fixture workspace.")
-    await expectBackground(message, scenario.accent ? "accent" : "layer-02", "background-color")
+    test("inventory updates leave send neutral; disabled and stop stay neutral", async ({ page }) => {
+      const view = await openSession(page, workspace, [{ directory: root }])
+      await view.input.fill("Keep this draft while the inventory changes.")
+      await expect(view.send).toBeEnabled()
+      await expectBackground(view.send, "contrast")
+      const url = page.url()
+
+      const refreshed = page.waitForResponse(
+        (response) =>
+          new URL(response.url()).pathname === `/api/worktree/${projectID}` && response.request().method() === "GET",
+      )
+      view.worktrees.push({ directory: workspace, strategy: "git" })
+      view.events.push({
+        id: "evt_workspace_accent_inventory",
+        created: 1700000001000,
+        type: "worktree.updated",
+        data: { projectID },
+      })
+      expect((await refreshed).ok()).toBe(true)
+      await expectBackground(view.send, "contrast")
+      await expect(page).toHaveURL(url)
+      await expect(view.input).toHaveText("Keep this draft while the inventory changes.")
+      await expect(view.send).toBeEnabled()
+
+      await view.input.fill("")
+      await expect(view.send).toBeDisabled()
+      await expectBackground(view.send, "contrast")
+
+      view.events.push({
+        id: "evt_workspace_accent_running",
+        created: 1700000002000,
+        type: "session.execution.started",
+        durable: { aggregateID: sessionID, seq: 1, version: 1 },
+        data: { sessionID },
+      })
+      const stop = view.composer.getByRole("button", { name: "Stop", exact: true })
+      await expect(stop).toBeEnabled()
+      await expectBackground(stop, "contrast")
+
+      await view.input.fill("Send a follow-up instead of stopping.")
+      await expect(view.send).toBeEnabled()
+      await expectBackground(view.send, "contrast")
+      await expect(page).toHaveURL(url)
+    })
+
+    test("new workspace send button stays neutral", async ({ page }) => {
+      const view = await openSession(page, root, [...inventory], true)
+      await expect(view.send).toBeDisabled()
+      await expectBackground(view.send, "contrast")
+      await page.getByRole("button", { name: "Local", exact: true }).click()
+      await page.getByRole("menuitem", { name: "New workspace", exact: true }).click()
+      await expect(page.getByRole("button", { name: "New workspace", exact: true })).toBeVisible()
+      await view.input.fill("Inspect this fixture workspace.")
+      await expect(view.send).toBeEnabled()
+      await expectBackground(view.send, "contrast")
+      await view.send.hover()
+      await expectBackground(view.send, "contrast")
+      await view.composer.locator('[data-action="composer-model"]').press("Tab")
+      await expect(view.send).toBeFocused()
+      await expectBackground(view.send, "contrast")
+    })
   })
 }
 
-test("inventory updates recolor the send button without navigation; disabled and stop stay neutral", async ({
-  page,
-}) => {
-  const view = await openSession(page, workspace, [{ directory: root }])
-  await view.input.fill("Keep this draft while the inventory changes.")
-  await expect(view.send).toBeEnabled()
-  await expectBackground(view.send, "contrast")
-  const url = page.url()
-
-  const refreshed = page.waitForResponse(
-    (response) =>
-      new URL(response.url()).pathname === `/api/worktree/${projectID}` && response.request().method() === "GET",
-  )
-  view.worktrees.push({ directory: workspace, strategy: "git" })
-  view.events.push({
-    id: "evt_workspace_accent_inventory",
-    created: 1700000001000,
-    type: "worktree.updated",
-    data: { projectID },
-  })
-  expect((await refreshed).ok()).toBe(true)
-  await expectBackground(view.send, "accent")
-  await expect(page).toHaveURL(url)
-  await expect(view.input).toHaveText("Keep this draft while the inventory changes.")
-  await expect(view.send).toBeEnabled()
-
-  await view.input.fill("")
-  await expect(view.send).toBeDisabled()
-  await expectBackground(view.send, "contrast")
-
-  view.events.push({
-    id: "evt_workspace_accent_running",
-    created: 1700000002000,
-    type: "session.execution.started",
-    durable: { aggregateID: sessionID, seq: 1, version: 1 },
-    data: { sessionID },
-  })
-  const stop = view.composer.getByRole("button", { name: "Stop", exact: true })
-  await expect(stop).toBeEnabled()
-  await expectBackground(stop, "contrast")
-
-  await view.input.fill("Send a follow-up instead of stopping.")
-  await expect(view.send).toBeEnabled()
-  await expectBackground(view.send, "accent")
-  await expect(page).toHaveURL(url)
-})
-
-async function openSession(page: Page, directory: string, worktrees = [...inventory]) {
+async function openSession(page: Page, directory: string, worktrees = [...inventory], draft = false) {
   const events: OpenCodeEvent[] = []
   await mockOpenCodeServer(page, {
     directory,
@@ -159,18 +198,32 @@ async function openSession(page: Page, directory: string, worktrees = [...invent
     if (route.request().method() !== "GET") return route.fallback()
     return route.fulfill({ json: worktrees, headers: { "access-control-allow-origin": "*" } })
   })
-  await page.addInitScript(() => {
-    localStorage.setItem("opencode-theme-id", "oc-2")
-    localStorage.setItem("opencode-color-scheme", "light")
-  })
+  if (draft)
+    await page.addInitScript(
+      ({ root, server }) => {
+        localStorage.setItem(
+          "opencode.global.dat:server",
+          JSON.stringify({
+            projects: { local: [{ worktree: root, expanded: true }] },
+            lastProject: { local: root },
+          }),
+        )
+        localStorage.setItem(
+          "opencode.window.browser.dat:tabs",
+          JSON.stringify([{ type: "draft", draftID: "draft_workspace_accent", server, directory: root }]),
+        )
+      },
+      { root, server },
+    )
   const loaded = page.waitForResponse(
     (response) =>
       new URL(response.url()).pathname === `/api/worktree/${projectID}` && response.request().method() === "GET",
   )
-  await page.goto(`/server/${base64Encode(server)}/session/${sessionID}`)
+  await page.goto(
+    draft ? "/new-session?draftId=draft_workspace_accent" : `/server/${base64Encode(server)}/session/${sessionID}`,
+  )
   expect((await loaded).ok()).toBe(true)
-  await expectSessionReady(page, { server, sessionID, title })
-  await expect(page.locator("html")).toHaveAttribute("data-color-scheme", "light")
+  if (!draft) await expectSessionReady(page, { server, sessionID, title })
   const composer = page.locator('[data-component="composer"]')
   await expectAppVisible(composer)
   const input = composer.getByRole("textbox", { name: "Prompt", exact: true })

packages/app/e2e/smoke/session-timeline.spec.ts

@@ -355,6 +355,14 @@ test.describe("smoke: session timeline", () => {
     await expectCanScrollToStart(page, expectedPartIDs, expectedMessageIDs, errors)
 
     const shell = page.locator(`[data-timeline-part-id="${fixture.expected.expandedShellPartID}"]`)
+    // The shell is below a long diff; reveal it rather than depending on offscreen overscan.
+    while ((await shell.count()) === 0) {
+      const before = await timelineState(page)
+      await timelineScroller(page).press("PageDown")
+      await expect.poll(async () => (await timelineState(page)).signature).not.toBe(before.signature)
+    }
+    await shell.scrollIntoViewIfNeeded()
+    await expect(shell).toBeInViewport()
     const shellTrigger = shell.locator('[data-slot="collapsible-trigger"]')
     const shellSubtitle = shell.locator('[data-slot="basic-tool-tool-subtitle"]')
     await expect(shellSubtitle).toHaveCount(0)
@@ -694,6 +702,7 @@ async function expectSessionTimelineReady(
   expectedMessageIDs: string[],
   errors: string[],
 ) {
+  await expect(page.locator("[data-timeline-virtual-content]")).toHaveCSS("visibility", "visible")
   await waitForTimelineStable(page)
   for (const text of forbiddenText) await expect(page.getByText(text)).toHaveCount(0)
   const currentState = await timelineState(page)

packages/app/e2e/user-story/model-selection-flow.spec.ts

@@ -1,10 +1,16 @@
 import { expect, test } from "@playwright/test"
+import { fixture } from "../performance/timeline/session-timeline-stress.fixture"
+import { installStressSessionTabs, stressSessionHref } from "../performance/timeline/timeline-test-helpers"
 import { mockOpenCodeServer } from "../utils/mock-server"
 import { expectAppVisible } from "../utils/waits"
 
 const directory = "C:/OpenCode/NewProject"
 
 test("creates a session in a new project and selects its model", async ({ page }) => {
+  // An empty draft must remain usable when the file viewer is unavailable.
+  await page.route(/(?:\/_assets\/file-(?!icon-)[^/]+\.js|\/session-ui\/src\/components\/file\.tsx)(?:\?|$)/, (route) =>
+    route.abort(),
+  )
   await mockOpenCodeServer(page, {
     directory,
     project: {
@@ -60,7 +66,7 @@ test("creates a session in a new project and selects its model", async ({ page }
           { providerID: "opencode", modelID: "free-model", visibility: "show" },
           { providerID: "opencode-go", modelID: "go-model-1", visibility: "show" },
         ],
-        recent: [],
+        recent: [{ providerID: "opencode-go", modelID: "go-model-1" }],
         variant: {},
       }),
     )
@@ -81,11 +87,73 @@ test("creates a session in a new project and selects its model", async ({ page }
   await expectAppVisible(page.locator('[data-component="composer"]'))
 
   const modelControl = page.locator('[data-action="composer-model"]')
+  await expect(modelControl).toContainText("Go Model 1")
+  await modelControl.click()
+  await page.locator('[data-option-key="opencode:free-model"]').click()
+  await expect(modelControl).toContainText("Free Model")
+
   await modelControl.click()
-  await expect(page.locator('[data-option-key="opencode:free-model"]')).toBeVisible()
   const goModel = page.locator('[data-option-key="opencode-go:go-model-1"]')
   await expect(goModel).toBeVisible()
   await goModel.click()
 
   await expect(modelControl).toContainText("Go Model 1")
 })
+
+test("restores each existing session's model and variant when switching tabs", async ({ page }) => {
+  const sessions = ["A", "B"].map((name) => ({
+    ...fixture.sessions[0],
+    id: `ses_model_${name}`,
+    title: `Model ${name}`,
+    model: { id: `model-${name}`, providerID: "opencode", variant: "balanced" },
+  }))
+  await mockOpenCodeServer(page, {
+    ...fixture,
+    sessions,
+    provider: {
+      all: [
+        {
+          id: "opencode",
+          name: "OpenCode",
+          models: Object.fromEntries(
+            sessions.map((session) => [
+              session.model.id,
+              {
+                id: session.model.id,
+                name: session.title,
+                limit: { context: 200_000 },
+                variants: { balanced: {}, high: {} },
+              },
+            ]),
+          ),
+        },
+      ],
+      connected: ["opencode"],
+      default: { providerID: "opencode", modelID: sessions[0]!.model.id },
+    },
+    pageMessages: () => ({ items: [] }),
+  })
+  await installStressSessionTabs(page, { sessionIDs: sessions.map((session) => session.id) })
+
+  const hrefA = stressSessionHref(sessions[0]!.id)
+  const hrefB = stressSessionHref(sessions[1]!.id)
+  await page.goto(hrefA)
+  const composer = page.locator('[data-component="composer"]')
+  const modelControl = composer.locator('[data-action="composer-model"]')
+  const variant = composer.getByRole("button", { name: "Choose model variant", exact: true })
+  await expect(modelControl).toHaveText("Model A")
+  await expect(variant).toHaveText("balanced")
+  await variant.click()
+  await page.getByRole("menuitemradio", { name: "high", exact: true }).click()
+  await expect(variant).toHaveText("high")
+
+  await page.locator(`[data-titlebar-tab-link][href="${hrefB}"]`).click()
+  await expect(page).toHaveURL(hrefB)
+  await expect(modelControl).toHaveText("Model B")
+  await expect(variant).toHaveText("balanced")
+
+  await page.locator(`[data-titlebar-tab-link][href="${hrefA}"]`).click()
+  await expect(page).toHaveURL(hrefA)
+  await expect(modelControl).toHaveText("Model A")
+  await expect(variant).toHaveText("high")
+})

packages/app/e2e/utils/mock-server.ts

@@ -47,7 +47,6 @@ type MockStreamWindow = Window & {
 }
 
 export async function mockOpenCodeServer(page: Page, config: MockServerConfig) {
-  const state = { cursors: new Map<string, string>(), nextCursor: 0 }
   const server = `http://${process.env.PLAYWRIGHT_SERVER_HOST ?? "127.0.0.1"}:${process.env.PLAYWRIGHT_SERVER_PORT ?? "4096"}`
 
   await page.addInitScript(
@@ -135,13 +134,7 @@ export async function mockOpenCodeServer(page: Page, config: MockServerConfig) {
     }, 50)
     page.on("close", () => clearInterval(timer))
   }
-  const transport = HttpRouter.toWebHandler(
-    HttpApiBuilder.layer(MockApi).pipe(
-      Layer.provide(mockHandlers(config, state)),
-      Layer.provide(HttpServer.layerServices),
-    ),
-    { disableLogger: true },
-  )
+  const transport = createMockServerHandler(config)
   page.on("close", () => void transport.dispose())
 
   await page.route("**/api/**", async (route) => {
@@ -173,6 +166,16 @@ export async function mockOpenCodeServer(page: Page, config: MockServerConfig) {
   })
 }
 
+export function createMockServerHandler(config: MockServerConfig) {
+  return HttpRouter.toWebHandler(
+    HttpApiBuilder.layer(MockApi).pipe(
+      Layer.provide(mockHandlers(config, { cursors: new Map<string, string>(), nextCursor: 0 })),
+      Layer.provide(HttpServer.layerServices),
+    ),
+    { disableLogger: true },
+  )
+}
+
 const corsHeaders = {
   "access-control-allow-origin": "*",
   "access-control-allow-headers": "*",

packages/app/package.json

@@ -34,6 +34,8 @@
     "test:service-worker": "bun run build && playwright test --config e2e/service-worker/playwright.config.ts",
     "test:stability": "bun test ./e2e/performance/unit/visual-stability.test.ts && playwright test --config e2e/performance/timeline-stability/playwright.config.ts",
     "test:bench": "bun test ./e2e/performance/unit && playwright test --config e2e/performance/playwright.config.ts",
+    "bench:tabs": "PLAYWRIGHT_BUILD=1 playwright test --config e2e/performance/playwright.config.ts timeline/session-tab-switch-benchmark.spec.ts --repeat-each=20 --workers=1 --retries=0 --reporter=line,./e2e/performance/tab-switch-reporter.ts",
+    "bench:entry": "PLAYWRIGHT_BUILD=1 playwright test --config e2e/performance/playwright.config.ts timeline/session-entry-benchmark.spec.ts --repeat-each=20 --workers=1 --retries=0 --reporter=line,./e2e/performance/tab-switch-reporter.ts",
     "test:bench:devex": "bun test ./e2e/performance/unit/desktop-startup.test.ts && playwright test --config e2e/performance/devex/playwright.config.ts"
   },
   "license": "MIT",

packages/app/src/composer/composer.tsx

@@ -12,12 +12,7 @@ import { formatKeybind, useCommand } from "@/shell/commands/command"
 import { useLanguage } from "@/runtime/i18n/language"
 import type { ComposerModel } from "./model"
 
-export function Composer(props: {
-  class?: string
-  model: ComposerModel
-  borderUnderlay?: boolean
-  accentSubmit?: boolean
-}) {
+export function Composer(props: { class?: string; model: ComposerModel; borderUnderlay?: boolean }) {
   const dialog = useDialog()
   const command = useCommand()
   const language = useLanguage()
@@ -26,7 +21,6 @@ export function Composer(props: {
     <div class="flex flex-col gap-3">
       <ComposerEditor
         controller={props.model}
-        accentSubmit={props.accentSubmit}
         borderUnderlay={props.borderUnderlay}
         class={props.class}
         modelControlsVisible={!props.model.model.loading}

packages/app/src/composer/editor/editor.tsx

@@ -37,7 +37,6 @@ export type ComposerMode = "normal" | "shell"
 
 export type ComposerEditorProps = {
   controller: ComposerEditorModel
-  accentSubmit?: boolean
   disabled?: boolean
   readOnly?: boolean
   borderUnderlay?: boolean
@@ -151,7 +150,6 @@ export function ComposerEditor(props: ComposerEditorProps) {
             ref={(element) => {
               editor = element
               props.controller.setEditor(element)
-              renderComposerEditor(element, props.controller.parts())
             }}
             data-component="composer-editor"
             role="textbox"
@@ -265,7 +263,6 @@ export function ComposerEditor(props: ComposerEditorProps) {
             mode={state.mode}
             stopping={view.submit.stopping()}
             disabled={!props.controller.canSubmit()}
-            accent={props.accentSubmit}
             sendLabel={i18n.t("ui.promptInput.send")}
             stopLabel={i18n.t("ui.promptInput.stop")}
             onSubmit={() => props.controller.submit()}
@@ -751,7 +748,6 @@ export function ComposerEditorSubmitButton(props: {
   mode: ComposerMode
   stopping: boolean
   disabled: boolean
-  accent?: boolean
   sendLabel: string
   stopLabel: string
   onSubmit: () => void
@@ -770,16 +766,10 @@ export function ComposerEditorSubmitButton(props: {
         tabIndex={props.mode === "normal" ? undefined : -1}
         icon={<Icon name={props.stopping ? "stop" : props.mode === "shell" ? "arrow-undo-down" : "arrow-up"} />}
         variant="contrast"
-        class="size-7 rounded-md p-[6px] shadow-[var(--v2-elevation-button-contrast)] disabled:opacity-50"
-        classList={{
-          "text-v2-text-text-contrast": !!props.accent && !props.stopping && !props.disabled,
-          "text-v2-icon-icon-muted": !props.accent || props.stopping || props.disabled,
-        }}
+        class="size-7 rounded-md p-[6px] text-v2-icon-icon-muted shadow-[var(--v2-elevation-button-contrast)] disabled:opacity-50"
         style={{
           "background-image":
-            props.accent && !props.stopping && !props.disabled
-              ? "linear-gradient(180deg,var(--v2-alpha-light-20) 0%,var(--v2-alpha-light-0) 100%),linear-gradient(90deg,var(--v2-background-bg-accent) 0%,var(--v2-background-bg-accent) 100%)"
-              : "linear-gradient(180deg,var(--v2-alpha-light-20) 0%,var(--v2-alpha-light-0) 100%),linear-gradient(90deg,var(--v2-background-bg-contrast) 0%,var(--v2-background-bg-contrast) 100%)",
+            "linear-gradient(180deg,var(--v2-alpha-light-20) 0%,var(--v2-alpha-light-0) 100%),linear-gradient(90deg,var(--v2-background-bg-contrast) 0%,var(--v2-background-bg-contrast) 100%)",
         }}
         aria-label={props.stopping ? props.stopLabel : props.sendLabel}
         onClick={(event) => {

packages/app/src/home/sessions/controller.tsx

@@ -278,16 +278,15 @@ export function createHomeSessionsController(home: HomeController) {
         const directory = project?.worktree ?? session.location.directory
         const ctx = home.server.focusedContext()
         if (!ctx) return
-        ctx.data.session.remember(session)
-        ctx.projects.open(directory)
-        if (options?.background) {
-          tabs.addSessionTab({ server: connKey, sessionId: session.id })
-          return
-        }
-        ctx.projects.touch(directory)
+        if (!options?.background) void ctx.data.session.message.sync(session.id).catch(() => undefined)
+        // Commit cache/project changes with navigation instead of rebuilding
+        // the outgoing Home list before leaving it.
         void startTransition(() => {
           const tab = tabs.addSessionTab({ server: connKey, sessionId: session.id })
-          tabs.select(tab)
+          if (!options?.background) tabs.select(tab)
+          ctx.data.session.remember(session)
+          ctx.projects.open(directory)
+          if (!options?.background) ctx.projects.touch(directory)
         })
       },
       archive: async (session: SessionInfo) => {

packages/app/src/new-session/view.tsx

@@ -48,7 +48,7 @@ export function NewSessionView(props: {
           <div class={NEW_SESSION_CONTENT_WIDTH}>
             <Wordmark class="h-auto w-full text-v2-background-bg-inverse" />
             <div class="mt-8 flex flex-col gap-8">
-              <Composer model={props.composer} accentSubmit={props.workspace.selection.workspace()} />
+              <Composer model={props.composer} />
               <Show when={props.project.empty()}>
                 <PromptProjectAddButton controller={props.project} />
               </Show>

packages/app/src/providers/models/selection.tsx

@@ -221,7 +221,7 @@ export const { use: useLocal, provider: LocalProvider } = createSimpleContext({
       },
     }
 
-    const current = () => {
+    const current = createMemo(() => {
       const item = firstModel(
         () => scope()?.model,
         () => agent.current()?.model,
@@ -229,7 +229,7 @@ export const { use: useLocal, provider: LocalProvider } = createSimpleContext({
       )
       if (!item) return
       return models.find(item)
-    }
+    })
 
     const configured = () => {
       const item = agent.current()

packages/app/src/runtime/platform/web.ts

@@ -53,7 +53,7 @@ export function createWebPlatform(version: string) {
 }
 
 function getCurrentServerUrl() {
-  if (location.hostname.includes("opencode.ai")) return "http://localhost:4096"
+  if (location.hostname.includes("opencode.ai")) return "http://localhost:49374"
   if (import.meta.env.DEV)
     return `http://${import.meta.env.VITE_OPENCODE_SERVER_HOST ?? "localhost"}:${import.meta.env.VITE_OPENCODE_SERVER_PORT ?? "4096"}`
   return location.origin

packages/app/src/session/composer/region.tsx

@@ -216,7 +216,6 @@ export type ActiveSessionRegionModel = ReturnType<typeof createActiveSessionRegi
 export function ActiveSessionComposerRegion(props: {
   model: ActiveSessionRegionModel
   session: SessionModel
-  accentSubmit: boolean
   onResponseSubmit: () => void
 }) {
   const settings = useSettings()
@@ -251,7 +250,7 @@ export function ActiveSessionComposerRegion(props: {
         <div class="relative">
           <SessionQueuePanel queue={queue} />
           <div class="relative z-10">
-            <Composer model={composer} borderUnderlay accentSubmit={props.accentSubmit} />
+            <Composer model={composer} borderUnderlay />
           </div>
         </div>
       }

packages/app/src/session/requests/background.ts

@@ -0,0 +1,117 @@
+import type { SessionInfo, SessionMessageAssistant, SessionMessageInfo, ShellInfo } from "@opencode-ai/client/promise"
+import { createMemo } from "solid-js"
+
+type Task =
+  | { id: string; type: "subagent"; label: string; agent?: string }
+  | { id: string; type: "shell"; label: string }
+
+export function createSessionBackground(input: {
+  sessionID: () => string | undefined
+  messages: (id: string) => SessionMessageInfo[]
+  sessions: () => SessionInfo[]
+  status: (id: string) => "idle" | "running"
+  shells: () => ShellInfo[]
+}) {
+  const history = createMemo(() => {
+    const completed = new Set<string>()
+    const subagents: { id: string; type: "subagent"; label: string; agent: string | undefined }[] = []
+    const shells: { partID: string; task: { id: string; type: "shell"; label: string } }[] = []
+    const id = input.sessionID()
+    const assistant = (id ? input.messages(id) : []).reduce<SessionMessageAssistant | undefined>((latest, message) => {
+      if (message.type === "synthetic") {
+        if (message.metadata?.source === "subagent" && typeof message.metadata.childID === "string")
+          completed.add(message.metadata.childID)
+        if (message.metadata?.source === "shell") {
+          if (typeof message.metadata.shellID === "string") completed.add(message.metadata.shellID)
+          if (typeof message.metadata.jobID === "string") completed.add(message.metadata.jobID)
+        }
+        return latest
+      }
+      if (message.type !== "assistant") return latest
+      message.content.forEach((part) => {
+        if (part.type !== "tool" || (part.name !== "subagent" && part.name !== "shell")) return
+        if (part.state.status !== "completed" || part.state.metadata?.status !== "running") return
+        if (part.name === "subagent") {
+          const sessionID = part.state.metadata.sessionID
+          if (typeof sessionID !== "string") return
+          const description = part.state.input.description
+          const agent = part.state.input.agent
+          subagents.push({
+            id: sessionID,
+            type: "subagent",
+            label: typeof description === "string" ? description : sessionID,
+            agent: typeof agent === "string" ? agent : undefined,
+          })
+          return
+        }
+        const shellID = part.state.metadata.shellID
+        const command = part.state.input.command
+        shells.push({
+          partID: part.id,
+          task: {
+            id: typeof shellID === "string" ? shellID : part.id,
+            type: "shell",
+            label: typeof command === "string" ? command : part.id,
+          },
+        })
+      })
+      return message.time.completed === undefined ? message : latest
+    }, undefined)
+
+    return {
+      // Completion notices can identify the shell or its original tool call.
+      subagents: subagents.filter((task) => !completed.has(task.id)),
+      shells: shells
+        .filter((item) => !completed.has(item.partID) && !completed.has(item.task.id))
+        .map((item) => item.task),
+      blocking:
+        assistant?.content.flatMap((part) => {
+          if (part.type !== "tool" || part.state.status !== "running") return []
+          if (part.name !== "shell" && part.name !== "subagent") return []
+          const value = part.name === "shell" ? part.state.metadata.shellID : part.state.metadata.sessionID
+          const label = part.name === "shell" ? part.state.input.command : part.state.input.description
+          return [
+            {
+              type: part.name as "shell" | "subagent",
+              partID: part.id,
+              id: typeof value === "string" ? value : undefined,
+              label: typeof label === "string" ? label : undefined,
+            },
+          ]
+        }) ?? [],
+    }
+  })
+  const blocking = createMemo(() => history().blocking)
+  const tasks = createMemo(() => {
+    const id = input.sessionID()
+    if (!id) return []
+    const current = history()
+    const active = input.sessions().flatMap((info) => {
+      if (info?.parentID !== id) return []
+      if (input.status(info.id) === "idle") return []
+      if (
+        current.blocking.some(
+          (item) => item.type === "subagent" && (item.id === info.id || (!!item.label && info.title === item.label)),
+        )
+      )
+        return []
+      return [{ id: info.id, type: "subagent" as const, label: info.title ?? info.id }]
+    })
+    const running = input.shells().flatMap((shell) => {
+      if (shell.status !== "running" || shell.metadata.sessionID !== id) return []
+      if (
+        current.blocking.some(
+          (item) => item.type === "shell" && (item.id === shell.id || (!!item.label && shell.command === item.label)),
+        )
+      )
+        return []
+      return [{ id: shell.id, type: "shell" as const, label: shell.command }]
+    })
+    return [
+      ...new Map<string, Task>(
+        [...current.subagents, ...active, ...current.shells, ...running].map((task) => [task.id, task]),
+      ).values(),
+    ]
+  })
+  return { blocking, tasks }
+}

packages/app/src/session/requests/model.ts

@@ -8,6 +8,7 @@ import { useLanguage } from "@/runtime/i18n/language"
 import { useSettings } from "@/settings/model"
 import { useWorkspaceLocation } from "@/workspaces/location"
 import { sessionPermissionRequest, sessionQuestionForm } from "@/session/requests/session-request-tree"
+import { createSessionBackground } from "@/session/requests/background"
 import { useData } from "@/runtime/server/current"
 
 export function createSessionRequestModel() {
@@ -46,104 +47,12 @@ export function createSessionRequestModel() {
     const id = params.id
     return !!id && !data.session.get(id)?.parentID
   }
-  const backgroundBlocking = createMemo(() => {
-    if (!primary()) return []
-    const id = params.id
-    if (!id) return []
-    const assistant = data.session.message
-      .list(id)
-      .findLast((message) => message.type === "assistant" && message.time.completed === undefined)
-    if (assistant?.type !== "assistant") return []
-    return assistant.content.flatMap((part) => {
-      if (part.type !== "tool" || part.state.status !== "running") return []
-      if (part.name !== "shell" && part.name !== "subagent") return []
-      const value = part.name === "shell" ? part.state.metadata.shellID : part.state.metadata.sessionID
-      const label = part.name === "shell" ? part.state.input.command : part.state.input.description
-      return [
-        {
-          type: part.name as "shell" | "subagent",
-          partID: part.id,
-          id: typeof value === "string" ? value : undefined,
-          label: typeof label === "string" ? label : undefined,
-        },
-      ]
-    })
-  })
-  const backgroundTasks = createMemo(() => {
-    if (!primary()) return []
-    const id = params.id
-    if (!id) return []
-    const blocking = backgroundBlocking()
-    const messages = data.session.message.list(id)
-    const completed = new Set(
-      messages.flatMap((message) => {
-        if (message.type !== "synthetic") return []
-        if (message.metadata?.source === "subagent" && typeof message.metadata.childID === "string")
-          return [message.metadata.childID]
-        if (message.metadata?.source === "shell" && typeof message.metadata.jobID === "string")
-          return [message.metadata.jobID]
-        return []
-      }),
-    )
-    const backgrounded = messages.flatMap((message) => {
-      if (message.type !== "assistant") return []
-      return message.content.flatMap((part) => {
-        if (part.type !== "tool" || part.name !== "subagent") return []
-        if (part.state.status !== "completed" || part.state.metadata?.status !== "running") return []
-        const sessionID = part.state.metadata.sessionID
-        if (typeof sessionID !== "string" || completed.has(sessionID)) return []
-        const description = part.state.input.description
-        const agent = part.state.input.agent
-        return [
-          {
-            id: sessionID,
-            type: "subagent" as const,
-            label: typeof description === "string" ? description : sessionID,
-            agent: typeof agent === "string" ? agent : undefined,
-          },
-        ]
-      })
-    })
-    const active = data.session.list().flatMap((info) => {
-      if (info?.parentID !== id) return []
-      if (data.session.status(info.id) === "idle") return []
-      if (
-        blocking.some(
-          (item) => item.type === "subagent" && (item.id === info.id || (!!item.label && info.title === item.label)),
-        )
-      )
-        return []
-      return [{ id: info.id, type: "subagent" as const, label: info.title ?? info.id }]
-    })
-    const backgroundShells = messages.flatMap((message) => {
-      if (message.type !== "assistant") return []
-      return message.content.flatMap((part) => {
-        if (part.type !== "tool" || part.name !== "shell" || completed.has(part.id)) return []
-        if (part.state.status !== "completed" || part.state.metadata?.status !== "running") return []
-        const shellID = part.state.metadata.shellID
-        const command = part.state.input.command
-        return [
-          {
-            id: typeof shellID === "string" ? shellID : part.id,
-            type: "shell" as const,
-            label: typeof command === "string" ? command : part.id,
-          },
-        ]
-      })
-    })
-    const running = data.shell.list({ directory: sdk().directory }).flatMap((shell) => {
-      if (shell.status !== "running" || shell.metadata.sessionID !== id) return []
-      if (
-        blocking.some(
-          (item) => item.type === "shell" && (item.id === shell.id || (!!item.label && shell.command === item.label)),
-        )
-      )
-        return []
-      return [{ id: shell.id, type: "shell" as const, label: shell.command }]
-    })
-    return [
-      ...new Map([...backgrounded, ...active, ...backgroundShells, ...running].map((task) => [task.id, task])).values(),
-    ]
+  const background = createSessionBackground({
+    sessionID: () => (primary() ? params.id : undefined),
+    messages: data.session.message.list,
+    sessions: data.session.list,
+    status: data.session.status,
+    shells: () => data.shell.list({ directory: sdk().directory }),
   })
   const moveToBackground = async () => {
     if (!primary()) return
@@ -190,8 +99,8 @@ export function createSessionRequestModel() {
     permissionRequest,
     permissionResponding,
     background: {
-      blocking: backgroundBlocking,
-      tasks: backgroundTasks,
+      blocking: background.blocking,
+      tasks: background.tasks,
       move: moveToBackground,
     },
     decide,

packages/app/src/session/screen.tsx

@@ -145,12 +145,7 @@ export function SessionScreen(props: { session: SessionModel }) {
 
       <Show when={!review.mobile.changes() ? session.identity.params.id : undefined} keyed>
         {(_id) => (
-          <ActiveSessionComposerRegion
-            model={composer}
-            session={session}
-            accentSubmit={session.workspace.current()}
-            onResponseSubmit={timeline.actions.resume}
-          />
+          <ActiveSessionComposerRegion model={composer} session={session} onResponseSubmit={timeline.actions.resume} />
         )}
       </Show>
       <Show when={!!session.identity.params.id && mobileTabsBottom()}>

packages/app/src/session/session-resolution.test.ts

@@ -5,18 +5,27 @@ import { createSessionResolution } from "./session-resolution"
 describe("session resolution", () => {
   test("waits for a route session ID", () => {
     createRoot((dispose) => {
-      let syncs = 0
+      const syncs = { session: 0, message: 0 }
       const sessions = {
         get: () => undefined,
         sync: () => {
-          syncs++
+          syncs.session++
           return Promise.resolve()
         },
+        message: {
+          sync: () => {
+            syncs.message++
+            return Promise.resolve()
+          },
+        },
       }
-      const session = createSessionResolution(() => undefined, () => sessions)
+      const session = createSessionResolution(
+        () => undefined,
+        () => sessions,
+      )
 
       expect(session()).toBeUndefined()
-      expect(syncs).toBe(0)
+      expect(syncs).toEqual({ session: 0, message: 0 })
       dispose()
     })
   })

packages/app/src/session/session-resolution.ts

@@ -1,9 +1,12 @@
-import { createEffect, createMemo, createSignal, on, onCleanup } from "solid-js"
+import { createMemo, createRenderEffect, createSignal, on, onCleanup } from "solid-js"
 import { sessionNotFoundError } from "@/runtime/server/errors"
 
 type SessionStore<T> = {
   get: (id: string) => T | undefined
   sync: (id: string, options?: { children?: boolean }) => Promise<unknown>
+  message: {
+    sync: (id: string) => Promise<unknown>
+  }
 }
 
 type Resolution<T> = { id: string; store: SessionStore<T> } & (
@@ -40,13 +43,17 @@ export function createSessionResolution<T>(
   })
   const [status, setStatus] = createSignal<Resolution<T>>()
 
-  createEffect(
+  // Start independent reads before constructing the selected view, including
+  // when its metadata is cached but its transcript has never been loaded.
+  createRenderEffect(
     on([sessionID, sessions] as const, ([id, store]) => {
       if (!id) return
       let stale = false
       onCleanup(() => {
         stale = true
       })
+      // The timeline owns message errors; metadata resolution stays independent.
+      void store.message.sync(id).catch(() => undefined)
       if (cached() && !options?.children) {
         setStatus({ id, store, state: "settled" })
         return

packages/app/src/session/timeline/controller-projection.test.ts

@@ -79,6 +79,17 @@ describe("visibleTimelineMessages", () => {
           ?.map((message) => message.id),
       ).toEqual(["msg_2", "msg_5"])
       expect(projection.assistantMessagesByParent().has(steer.id)).toBe(false)
+      expect([...projection.messageRowIndex()]).toEqual([
+        ["msg_1", 0],
+        ["msg_3", 2],
+      ])
+      expect([...projection.messageLastRowIndex()]).toEqual([
+        ["msg_1", 1],
+        ["msg_3", 3],
+      ])
+      expect([...projection.lastAssistantGroupKey()]).toEqual([["msg_1", "context:msg_5:tool_read"]])
+      expect(projection.rowByKey().get("user-message:msg_1")).toBe(projection.rows()[0])
+      expect(projection.rowByKey().size).toBe(projection.rows().length)
       dispose()
     })
   })

packages/app/src/session/timeline/message-timeline.tsx

@@ -21,6 +21,7 @@ import { useData, useServer } from "@/runtime/server/current"
 import { useWorkspaceLocation } from "@/workspaces/location"
 import { Timeline, TimelineRow } from "@opencode-ai/session-ui/timeline/projection"
 import { createSessionTimelineRowRenderer } from "@opencode-ai/session-ui/timeline/row"
+import { getReadyMarkdown, preloadMarkdown } from "@opencode-ai/session-ui/markdown-cache"
 import { createTimelineController, type TimelineController, type TimelineSessionSource } from "./controller"
 import { createTimelineVirtualizer } from "./virtualizer"
 import { containsDirectory, isWorkspaceDirectory, workspaceDirectories } from "@/workspaces/paths"
@@ -316,6 +317,16 @@ type MessageTimelineProps = {
 
 export function MessageTimeline(props: MessageTimelineProps) {
   const controller = createTimelineController({ session: props.session })
+  const tail = props.pinned ? controller.data.projection.rows().at(-1) : undefined
+  if (tail?._tag === "AssistantPart" && tail.group.type === "part") {
+    const message = controller.data.projection.messageByID().get(tail.group.ref.messageID)
+    if (message?.type === "assistant" && message.time.completed !== undefined) {
+      const content = Timeline.resolveContent(message, tail.group.ref.partID)
+      // Start the required worker job while the rest of the selected view is constructed.
+      if (content?.type === "text" && content.text.trim())
+        void preloadMarkdown(content.text, tail.group.ref.partID).catch(() => undefined)
+    }
+  }
   return (
     <MessageTimelineView {...props} data={controller.data} action={controller.action} pending={controller.pending} />
   )
@@ -400,6 +411,38 @@ function MessageTimelineView(
     onSelectionInteraction: props.onSelectionInteraction,
     onUserScroll: props.onUserScroll,
     onHistoryScroll: props.onHistoryScroll,
+    canRenderImmediately: (row, disclosure) => {
+      if (row._tag === "TurnGap" || row._tag === "TurnDivider") return true
+      if (row._tag === "Notice") {
+        const message = messageByID().get(row.messageID)
+        return (
+          (message?.type === "system" || message?.type === "synthetic") &&
+          (message.description ?? message.text).length <= 1024
+        )
+      }
+      if (row._tag === "UserMessage") {
+        const message = messageByID().get(row.userMessageID)
+        if (message?.type !== "user" || message.text.length > 1024 || message.files?.length || message.agents?.length)
+          return false
+        const presentation = readPromptPresentation(message.metadata)
+        return (
+          (presentation?.displayText ?? message.text).length <= 1024 &&
+          !presentation?.comments?.length &&
+          !parseCommentNote(message.text)
+        )
+      }
+      if (row._tag !== "AssistantPart" || row.group.type !== "part") return false
+      const message = messageByID().get(row.group.ref.messageID)
+      if (message?.type !== "assistant" || message.time.completed === undefined) return false
+      const content = Timeline.resolveContent(message, row.group.ref.partID)
+      if (content?.type === "reasoning")
+        return !(disclosure[row.group.ref.partID] ?? props.data.reasoningMode() === "full")
+      return (
+        content?.type === "text" &&
+        content.text.length <= 1024 &&
+        !!getReadyMarkdown({ raw: content.text, src: content.text }, `${row.group.ref.partID}:0:full`)
+      )
+    },
     setRevealMessage: props.setRevealMessage,
     setScrollToEnd: props.setScrollToEnd,
   })

packages/app/src/session/timeline/model.ts

@@ -13,7 +13,6 @@ export {
 
 export function createTimelineModel(input: { session: Pick<SessionModel, "identity" | "history"> }) {
   const data = useData()
-  const prepared = new Set<string>()
 
   const [resource] = createResource(
     () => input.session.identity.sessionID(),
@@ -30,14 +29,12 @@ export function createTimelineModel(input: { session: Pick<SessionModel, "identi
         pause: () => new Promise((resolve) => setTimeout(resolve, leadingTurnPageDelay)),
         maxPages: leadingTurnPageLimit,
       }).catch(() => undefined)
-      if (input.session.identity.sessionKey() === key) prepared.add(key)
     },
   )
   const ready = createMemo(() => {
     const id = input.session.identity.sessionID()
-    if (!id || prepared.has(input.session.identity.sessionKey()) || !resource.loading) return true
-    const messages = data.session.message.list(id)
-    return messages.length > 0 && !leadingTurnNeedsParent(messages)
+    // Enrich the partial leading group without withholding the already loaded tail.
+    return !id || data.session.message.list(id).length > 0 || !resource.loading
   })
   const more = () => {
     const id = input.session.identity.sessionID()

packages/app/src/session/timeline/projection.ts

@@ -96,38 +96,29 @@ export function createTimelineProjection(input: {
   const rows = createMemo((previous: TimelineRow.TimelineRow[] | undefined) =>
     reuseTimelineRows(previous, projection().rows),
   )
-  const rowByKey = createMemo(() => new Map(rows().map((row) => [TimelineRow.key(row), row] as const)))
-  const messageRowIndex = createMemo(() => {
-    const result = new Map<string, number>()
+  const indexes = createMemo(() => {
+    const rowByKey = new Map<string, TimelineRow.TimelineRow>()
+    const messageRowIndex = new Map<string, number>()
+    const messageLastRowIndex = new Map<string, number>()
+    const lastAssistantGroupKey = new Map<string, string>()
     rows().forEach((row, index) => {
-      if (!("userMessageID" in row) || result.has(row.userMessageID)) return
-      result.set(row.userMessageID, index)
+      rowByKey.set(TimelineRow.key(row), row)
+      if (!("userMessageID" in row)) return
+      if (!messageRowIndex.has(row.userMessageID)) messageRowIndex.set(row.userMessageID, index)
+      messageLastRowIndex.set(row.userMessageID, index)
+      if (row._tag === "AssistantPart") lastAssistantGroupKey.set(row.userMessageID, row.group.key)
     })
-    return result
-  })
-  const messageLastRowIndex = createMemo(() => {
-    const result = new Map<string, number>()
-    rows().forEach((row, index) => {
-      if ("userMessageID" in row) result.set(row.userMessageID, index)
-    })
-    return result
-  })
-  const lastAssistantGroupKey = createMemo(() => {
-    const result = new Map<string, string>()
-    rows().forEach((row) => {
-      if (row._tag === "AssistantPart") result.set(row.userMessageID, row.group.key)
-    })
-    return result
+    return { rowByKey, messageRowIndex, messageLastRowIndex, lastAssistantGroupKey }
   })
 
   return {
     activeMessageID,
     assistantMessagesByParent,
-    lastAssistantGroupKey,
+    lastAssistantGroupKey: () => indexes().lastAssistantGroupKey,
     messageByID: sessionMessageByID,
-    messageRowIndex,
-    messageLastRowIndex,
-    rowByKey,
+    messageRowIndex: () => indexes().messageRowIndex,
+    messageLastRowIndex: () => indexes().messageLastRowIndex,
+    rowByKey: () => indexes().rowByKey,
     rows,
     sessionMessageByID,
     userContextByID,

packages/app/src/session/timeline/virtualizer.tsx

@@ -55,6 +55,10 @@ type Input = {
   onSelectionInteraction: (event: MouseEvent) => void
   onUserScroll: (target?: EventTarget | null) => void
   onHistoryScroll: () => void
+  canRenderImmediately?: (
+    row: TimelineRow.TimelineRow,
+    disclosure: Readonly<Record<string, boolean | undefined>>,
+  ) => boolean
   setRevealMessage?: (fn: (id: string) => void) => void
   setScrollToEnd?: (fn: () => void) => void
 }
@@ -75,17 +79,63 @@ export function createTimelineVirtualizer(input: Input) {
   const coldBottomMount = !initialMeasurements?.length && input.pinned()
   const [listRoot, setListRoot] = createSignal<HTMLDivElement>()
   const [toolOpen, setToolOpen] = createStore<Record<string, boolean | undefined>>(cached?.toolOpen ?? {})
-  const [overscan, setOverscan] = createSignal(2)
+  const [rendering, setRendering] = createStore({ initialTail: coldBottomMount })
   const rows = input.projection.rows
   const rowByKey = input.projection.rowByKey
-  const knownKeys = new Set(rows().map(TimelineRow.key))
+  const rowKeys = createMemo(() => rows().map(TimelineRow.key), undefined, {
+    equals: (previous, next) => previous.length === next.length && previous.every((key, index) => key === next[index]),
+  })
+  const knownKeys = new Set(rowKeys())
   const addedKeys = new Set<string>()
+  const getItemKey = createMemo(() => {
+    const keys = rowKeys()
+    keys
+      .filter((key) => !knownKeys.has(key))
+      .forEach((key) => {
+        knownKeys.add(key)
+        addedKeys.add(key)
+      })
+    return (index: number) => keys[index] ?? `removed:${index}`
+  })
+  const rangeExtractor = createMemo(() => {
+    const id = input.projection.activeMessageID()
+    const active = id ? (input.projection.messageLastRowIndex().get(id) ?? -1) : -1
+    const initialTail = rendering.initialTail && input.pinned()
+    return (range: Range) => {
+      // Batch a bounded cheap suffix, but stop before unknown/large content.
+      // A large tail still mounts alone before estimates expose earlier history.
+      const start = Math.max(0, range.startIndex - 2)
+      const boundary = initialTail
+        ? rows()
+            .slice(start, range.count)
+            .findLastIndex(
+              (row) =>
+                !(
+                  row._tag === "AssistantPart" &&
+                  row.group.type === "context" &&
+                  row.group.refs.length <= 16 &&
+                  !toolOpen[`context:${row.group.key}`]
+                ) && !input.canRenderImmediately?.(row, toolOpen),
+            )
+        : -1
+      const first = Math.min(range.count - 1, start + boundary + 1)
+      const indexes = initialTail
+        ? Array.from({ length: range.count - first }, (_, index) => first + index)
+        : defaultRangeExtractor({ ...range, overscan: 2 })
+      return filterVirtualIndexes(
+        [...new Set([...indexes, ...(active < 0 ? [] : [active])])].sort((a, b) => a - b),
+        range.count,
+      )
+    }
+  })
   const measuredElements = new WeakSet<Element>()
   let touchStart: number | undefined
   let pointerHeld = false
   let maxScroll = 0
   let virtualContent: HTMLDivElement | undefined
   let scrollTop = 0
+  let reportOffset: ((offset: number, scrolling: boolean) => void) | undefined
+  let batchingColdSizes = false
 
   const virtualizer = createVirtualizer<HTMLDivElement, HTMLDivElement>({
     get count() {
@@ -93,10 +143,16 @@ export function createTimelineVirtualizer(input: Input) {
     },
     getScrollElement: () => listRoot() ?? null,
     // Route navigation detaches and reattaches the scroll element, which drops its offset.
-    observeElementOffset: (instance, callback) =>
-      observeElementOffsetReconnectAware(instance, callback, () => {
+    observeElementOffset: (instance, callback) => {
+      reportOffset = (offset, scrolling) => {
+        callback(offset, scrolling)
+        settleColdBottom()
+      }
+      return observeElementOffsetReconnectAware(instance, reportOffset, () => {
         if (input.pinned()) virtualizer.scrollToEnd()
-      }),
+        settleColdBottom()
+      })
+    },
     initialOffset: () => (input.pinned() ? Number.MAX_SAFE_INTEGER : 0),
     initialMeasurementsCache: initialMeasurements,
     estimateSize: () => fallbackItemSize,
@@ -110,28 +166,17 @@ export function createTimelineVirtualizer(input: Input) {
       if (box) return Math.round(box.blockSize)
       if (initial) {
         const size = instance.itemSizeCache.get(instance.options.getItemKey(instance.indexFromElement(element)))
-        if (size !== undefined) return size
+        if (size !== undefined || coldPending) return size ?? fallbackItemSize
       }
       return element.offsetHeight
     },
     scrollToFn: (offset, options, instance) => {
+      if (batchingColdSizes && input.pinned()) return
       if (virtualContent) virtualContent.style.height = `${instance.getTotalSize()}px`
       elementScroll(offset, options, instance)
     },
     get getItemKey() {
-      const items = rows()
-      items
-        .map(TimelineRow.key)
-        .filter((key) => !knownKeys.has(key))
-        .forEach((key) => {
-          knownKeys.add(key)
-          addedKeys.add(key)
-        })
-      return (index: number) => {
-        const row = items[index]
-        if (!row) return `removed:${index}`
-        return TimelineRow.key(row)
-      }
+      return getItemKey()
     },
     get anchorTo() {
       return input.pinned() ? "end" : "start"
@@ -145,16 +190,7 @@ export function createTimelineVirtualizer(input: Input) {
     },
     paddingEnd: 64,
     get rangeExtractor() {
-      const id = input.projection.activeMessageID()
-      const active = id ? (input.projection.messageLastRowIndex().get(id) ?? -1) : -1
-      const buffer = overscan()
-      return (range: Range) => {
-        const indexes = defaultRangeExtractor({ ...range, overscan: buffer })
-        return filterVirtualIndexes(
-          [...new Set([...indexes, ...(active < 0 ? [] : [active])])].sort((a, b) => a - b),
-          range.count,
-        )
-      }
+      return rangeExtractor()
     },
   })
   const resizeItem = virtualizer.resizeItem
@@ -166,7 +202,7 @@ export function createTimelineVirtualizer(input: Input) {
     const row = rows()[index]
     if (!row) return
     const key = TimelineRow.key(row)
-    if (virtualizer.itemSizeCache.get(key) === size) {
+    if ((virtualizer.itemSizeCache.get(key) ?? fallbackItemSize) === size) {
       pendingSizes.delete(index)
       return
     }
@@ -178,12 +214,19 @@ export function createTimelineVirtualizer(input: Input) {
       if (!pendingSizes.size) return
       const sizes = [...pendingSizes]
       pendingSizes.clear()
+      // The hidden pinned mount needs one bottom write after the whole batch,
+      // not a layout-forcing scroll adjustment for every measured row.
+      batchingColdSizes = coldPending && input.pinned()
       batch(() => {
         sizes.forEach(([index, value]) => {
           const row = rows()[index]
           if (row && TimelineRow.key(row) === value.key) resizeItem(index, value.size)
         })
       })
+      batchingColdSizes = false
+      if (coldPending) pinColdBottom()
+      settleColdBottom()
+      if (coldPending) return
       if (!input.pinned()) return
       const root = listRoot()
       // Reopening a settled scroll-to-end operation can fight subsequent keyboard scrolling.
@@ -217,41 +260,73 @@ export function createTimelineVirtualizer(input: Input) {
     })
   })
 
-  let settleFrame: number | undefined
-  let overscanFrame: number | undefined
-  let overscanTimer: number | undefined
-  const expandOverscan = () => {
-    overscanFrame = requestAnimationFrame(() => {
-      overscanFrame = undefined
-      // Let the visible rows paint before building the normal interaction buffer.
-      overscanTimer = window.setTimeout(() => {
-        overscanTimer = undefined
-        setOverscan(20)
-      }, 0)
-    })
+  let coldPending = coldBottomMount
+  let settleQueued = false
+  let contentObserver: MutationObserver | undefined
+  let viewportObserver: ResizeObserver | undefined
+  const pinColdBottom = () => {
+    const root = listRoot()
+    if (!input.pinned() || !virtualContent || !root) return
+    // scrollToEnd computes its target from the DOM, not the new size cache.
+    virtualContent.style.height = `${virtualizer.getTotalSize()}px`
+    if (Math.abs(root.scrollHeight - root.clientHeight - root.scrollTop) > endEpsilon) virtualizer.scrollToEnd()
+    // Report after core size adjustments finish so they cannot apply a delta
+    // twice. This avoids waiting a frame for the native scroll event.
+    if (virtualizer.scrollOffset !== root.scrollTop) reportOffset?.(root.scrollTop, false)
+  }
+  const pendingMeasurements = () => {
+    const items = virtualizer.getVirtualItems()
+    return (
+      (rows().length > 0 && items.length === 0) ||
+      items.some((item) => !virtualizer.elementsCache.get(item.key)?.isConnected)
+    )
   }
-  const pendingMeasurements = () =>
-    virtualizer.getVirtualItems().some((item) => !virtualizer.itemSizeCache.has(item.key))
   const settleColdBottom = () => {
-    if (input.pinned()) virtualizer.scrollToEnd()
-    if (virtualContent?.querySelector(pendingMarkdown) || pendingMeasurements()) {
-      settleFrame = requestAnimationFrame(settleColdBottom)
-      return
-    }
-    settleFrame = requestAnimationFrame(() => {
-      if (input.pinned()) virtualizer.scrollToEnd()
-      if (virtualContent?.querySelector(pendingMarkdown) || pendingMeasurements()) {
+    if (!coldPending || settleQueued) return
+    settleQueued = true
+    queueMicrotask(() => {
+      settleQueued = false
+      const root = listRoot()
+      if (!coldPending || !virtualContent?.isConnected || !root) return
+      if (virtualContent.querySelector(pendingMarkdown)) return
+      if (!root.clientHeight) return
+      // Markdown can finish before ResizeObserver delivers its new box. The
+      // normal measureElement path skips reads while scrolling; this gate needs
+      // current boxes before expanding the estimated range or revealing it.
+      virtualizer.elementsCache.forEach((element) => {
+        if (element.isConnected) virtualizer.resizeItem(virtualizer.indexFromElement(element), element.offsetHeight)
+      })
+      if (pendingSizes.size || pendingMeasurements()) return
+      pinColdBottom()
+      if (input.pinned() && Math.abs(root.scrollHeight - root.clientHeight - root.scrollTop) > 1) return
+      // The scroll event must update the range before newly exposed rows can reveal.
+      if (root.scrollHeight > root.clientHeight && Math.abs((virtualizer.scrollOffset ?? 0) - root.scrollTop) > 1)
+        return
+      if (rendering.initialTail) {
+        setRendering("initialTail", false)
         settleColdBottom()
         return
       }
-      settleFrame = undefined
-      virtualContent?.style.removeProperty("visibility")
-      expandOverscan()
+      if (pendingSizes.size || pendingMeasurements() || virtualContent.querySelector(pendingMarkdown)) return
+      coldPending = false
+      contentObserver?.disconnect()
+      viewportObserver?.disconnect()
+      virtualContent.style.removeProperty("visibility")
     })
   }
   onMount(() => {
-    if (coldBottomMount) settleFrame = requestAnimationFrame(settleColdBottom)
-    if (!coldBottomMount) expandOverscan()
+    if (!coldPending || !virtualContent) return
+    contentObserver = new MutationObserver(settleColdBottom)
+    contentObserver.observe(virtualContent, {
+      childList: true,
+      subtree: true,
+      attributes: true,
+      attributeFilter: ["data-markdown-ready"],
+    })
+    viewportObserver = new ResizeObserver(settleColdBottom)
+    const root = listRoot()
+    if (root) viewportObserver.observe(root)
+    settleColdBottom()
   })
 
   let measuredSessionKey = input.sessionKey()
@@ -265,12 +340,14 @@ export function createTimelineVirtualizer(input: Input) {
 
   const bindListRoot = (root: HTMLDivElement) => {
     if (root === listRoot()) return
-    setListRoot(root)
     // TanStack owns anchoring; browser scroll anchoring would fight its adjustments.
     root.style.overflowAnchor = "none"
+    setListRoot(root)
     scrollTop = root.scrollTop
     maxScroll = root.scrollHeight - root.clientHeight
     input.setScrollRef(root)
+    viewportObserver?.observe(root)
+    settleColdBottom()
   }
 
   // Upward input is the one intent geometry cannot recover: nudging up while still a pixel from
@@ -278,13 +355,11 @@ export function createTimelineVirtualizer(input: Input) {
   const handleListWheel = (event: WheelEvent & { currentTarget: HTMLDivElement }) => {
     input.onUserScroll(event.target)
     if (event.deltaY < 0) input.onUnpin()
-    setOverscan(20)
   }
 
   const handleListTouchStart = (event: TouchEvent) => {
     input.onUserScroll(event.target)
     touchStart = event.touches[0]?.clientY
-    setOverscan(20)
   }
 
   const handleListTouchMove = (event: TouchEvent & { currentTarget: HTMLDivElement }) => {
@@ -301,7 +376,6 @@ export function createTimelineVirtualizer(input: Input) {
   const handleListPointerDown = (event: PointerEvent & { currentTarget: HTMLDivElement }) => {
     input.onUserScroll(event.target)
     pointerHeld = true
-    setOverscan(20)
   }
   const releasePointer = () => {
     pointerHeld = false
@@ -322,7 +396,6 @@ export function createTimelineVirtualizer(input: Input) {
     if (scrollKeyOwner(event.currentTarget, event.target, key) !== event.currentTarget) return
     input.onUserScroll(event.currentTarget)
     if (upwardKeys.has(key)) input.onUnpin()
-    setOverscan(20)
   }
 
   // Following resumes by arriving at the end, either by scrolling there or by content shrinking
@@ -338,6 +411,7 @@ export function createTimelineVirtualizer(input: Input) {
     const arrived = scrollTop > previousTop + endEpsilon || maxScroll < previousMaxScroll
     if (maxScroll <= 1 || (atEnd && arrived)) input.onPin()
     else if (pointerHeld && scrollTop < previousTop - endEpsilon) input.onUnpin()
+    settleColdBottom()
     input.onScheduleScrollState(root)
     input.onHistoryScroll()
   }
@@ -476,9 +550,9 @@ export function createTimelineVirtualizer(input: Input) {
     cache.delete(ownerSessionKey)
     cache.set(ownerSessionKey, { measurements: virtualizer.takeSnapshot(), toolOpen: { ...toolOpen } })
     while (cache.size > 16) cache.delete(cache.keys().next().value!)
-    if (settleFrame !== undefined) cancelAnimationFrame(settleFrame)
-    if (overscanFrame !== undefined) cancelAnimationFrame(overscanFrame)
-    if (overscanTimer !== undefined) window.clearTimeout(overscanTimer)
+    coldPending = false
+    contentObserver?.disconnect()
+    viewportObserver?.disconnect()
     input.setScrollRef(undefined)
     input.setRevealMessage?.(() => {})
     input.setScrollToEnd?.(() => {})

packages/app/src/shell/routes/routes.tsx

@@ -11,9 +11,8 @@ import Shell from "@/shell/shell"
 import { requireServerKey } from "./session"
 
 export const File = lazy(() => import("@opencode-ai/session-ui/file").then((module) => ({ default: module.File })))
-const loadDraftRoute = () => Promise.all([import("@/new-session/route"), File.preload()]).then(([module]) => module)
 const loadSessionRoute = () => Promise.all([import("@/session/route"), File.preload()]).then(([module]) => module)
-const DraftRoute = lazy(() => loadDraftRoute().then((module) => ({ default: module.DraftRoute })))
+const DraftRoute = lazy(() => import("@/new-session/route").then((module) => ({ default: module.DraftRoute })))
 const TargetSessionRouteContent = lazy(() =>
   loadSessionRoute().then((module) => ({ default: module.TargetSessionRouteContent })),
 )

packages/app/src/shell/shell.tsx

@@ -43,12 +43,12 @@ export default function Layout(props: ParentProps) {
         style={{
           "padding-top": "env(safe-area-inset-top, 0px)",
           "padding-bottom": "env(safe-area-inset-bottom, 0px)",
-          // The native Windows titlebar already includes the gap above the content panels.
+          // Native Windows chrome supplies the gap; retain paint clearance for the panels' outer outlines.
           "--shell-top-inset":
             platform.platform === "desktop" &&
             platform.os === "windows" &&
             !(mobile() && preferences.general.mobileTitlebarPosition() === "bottom")
-              ? "0px"
+              ? "1px"
               : "8px",
         }}
       >

packages/app/src/shell/titlebar/tab-nav.tsx

@@ -28,7 +28,6 @@ export function TabNavItem(props: {
   onClose: () => void
   onNavigate: () => void
   active?: boolean
-  forceTruncate?: boolean
   suppressNavigation?: boolean
   dragging?: boolean
   pressed?: boolean
@@ -98,11 +97,13 @@ export function TabNavItem(props: {
 
   createEffect(() => {
     title()
-    props.forceTruncate
+    props.active
+    props.orientation
     editing()
     scheduleTitleOverflow()
   })
 
+  // The overflow fade changes title padding; observe the stable tab box, not that feedback.
   createResizeObserver(() => tabRoot, scheduleTitleOverflow)
   onCleanup(() => {
     if (measureFrame !== undefined) cancelAnimationFrame(measureFrame)

packages/app/src/shell/titlebar/tab-strip.tsx

@@ -1,6 +1,5 @@
-import { createEffect, createMemo, createResource, For, onCleanup, onMount, Show } from "solid-js"
+import { createEffect, createMemo, createResource, For, onCleanup, Show } from "solid-js"
 import { createStore } from "solid-js/store"
-import { createResizeObserver } from "@solid-primitives/resize-observer"
 import { DragDropProvider, PointerSensor } from "@dnd-kit/solid"
 import { isSortable, useSortable } from "@dnd-kit/solid/sortable"
 import { Accessibility, AutoScroller, Feedback, PointerActivationConstraints } from "@dnd-kit/dom"
@@ -26,7 +25,6 @@ function SessionTabSlot(props: {
   id: string
   index: number
   active: boolean
-  forceTruncate: boolean
   orientation: "horizontal" | "vertical"
   session: SessionInfo | undefined
   fallbackTitle?: string
@@ -69,7 +67,6 @@ function SessionTabSlot(props: {
         onNavigate={() => props.onNavigate(ref)}
         onClose={props.onClose}
         active={props.active}
-        forceTruncate={props.forceTruncate}
         dragging={sortable.isDragSource()}
         orientation={props.orientation}
       />
@@ -82,7 +79,6 @@ function SessionTabEntry(props: {
   id: string
   index: number
   active: boolean
-  forceTruncate: boolean
   orientation: "horizontal" | "vertical"
   serverCtx: ServerCtx | undefined
   onVisibleChange: (visible: boolean) => void
@@ -169,7 +165,6 @@ function SessionTabEntry(props: {
         id={props.id}
         index={props.index}
         active={props.active}
-        forceTruncate={props.forceTruncate}
         orientation={props.orientation}
         session={session()}
         fallbackTitle={
@@ -238,19 +233,15 @@ export function TitlebarTabStrip(props: {
   orientation?: "horizontal" | "vertical"
   tabs: Tab[]
   currentTab: Tab | undefined
-  forceTruncate: boolean
   onNavigate: (tab: Tab, el?: HTMLDivElement) => void
   onClose: (tab: Tab) => void
   onReorder: (keys: string[]) => void
-  onOverflowChange: (overflowing: boolean) => void
 }) {
   const global = useGlobal()
   const language = useLanguage()
   const command = useCommand()
   const vertical = () => props.orientation === "vertical"
-  let scrollRef!: HTMLDivElement
   let listRef!: HTMLDivElement
-  let resizeFrame: number | undefined
   const [visibility, setVisibility] = createStore<Record<string, boolean>>({})
   const visibleTabs = createMemo(() => props.tabs.filter((tab) => tab.type === "draft" || visibility[tabKey(tab)]))
   const visibleTabIds = () => visibleTabs().map(tabKey)
@@ -281,38 +272,6 @@ export function TitlebarTabStrip(props: {
     if (next) props.onNavigate(next)
   }
 
-  function refreshOverflow() {
-    if (!scrollRef) return
-    props.onOverflowChange(
-      vertical() ? scrollRef.scrollHeight > scrollRef.clientHeight : scrollRef.scrollWidth > scrollRef.clientWidth,
-    )
-  }
-
-  createResizeObserver(
-    () => [scrollRef, listRef],
-    () => {
-      if (resizeFrame !== undefined) return
-      resizeFrame = requestAnimationFrame(() => {
-        resizeFrame = undefined
-        refreshOverflow()
-      })
-    },
-  )
-
-  onMount(() => {
-    refreshOverflow()
-  })
-
-  onCleanup(() => {
-    if (resizeFrame !== undefined) cancelAnimationFrame(resizeFrame)
-  })
-
-  createEffect(() => {
-    props.tabs.length
-    visibleTabIds()
-    refreshOverflow()
-  })
-
   return (
     <div
       data-slot={vertical() ? "vertical-tabs" : "titlebar-tabs"}
@@ -327,7 +286,6 @@ export function TitlebarTabStrip(props: {
           "flex-row items-center gap-1.5 overflow-x-auto": !vertical(),
           "max-h-full flex-col overflow-y-auto overflow-x-hidden": vertical(),
         }}
-        ref={scrollRef}
       >
         <DragDropProvider
           sensors={[
@@ -398,7 +356,6 @@ export function TitlebarTabStrip(props: {
                       id={id}
                       index={visibleIndex()}
                       active={props.currentTab === tab}
-                      forceTruncate={props.forceTruncate}
                       orientation={vertical() ? "vertical" : "horizontal"}
                       serverCtx={serverCtx()}
                       onVisibleChange={(visible) => setVisibility(id, visible)}

packages/app/src/shell/titlebar/titlebar.tsx

@@ -1,4 +1,4 @@
-import { createEffect, createMemo, createResource, Match, createSignal, Show, Switch, untrack } from "solid-js"
+import { createEffect, createMemo, createResource, Match, Show, Switch, untrack } from "solid-js"
 import { createStore } from "solid-js/store"
 import { Portal } from "solid-js/web"
 import { useLocation, useNavigate } from "@solidjs/router"
@@ -336,8 +336,6 @@ export function Titlebar(props: {
               ].filter((v) => v !== undefined)
             })
 
-            const [tabsAreOverflowing, setTabsAreOverflowing] = createSignal(false)
-
             return (
               <div
                 class="h-full flex-1 overflow-hidden flex flex-row items-center gap-1.5 px-2 md:pr-3"
@@ -382,8 +380,6 @@ export function Titlebar(props: {
                       <TitlebarTabStrip
                         tabs={tabsStore}
                         currentTab={currentTab()}
-                        forceTruncate={tabsAreOverflowing()}
-                        onOverflowChange={setTabsAreOverflowing}
                         onNavigate={(tab, el) => {
                           tabs.select(tab)
                           el?.scrollIntoView({ behavior: "instant" })
@@ -424,8 +420,6 @@ export function Titlebar(props: {
                             orientation="vertical"
                             tabs={tabsStore}
                             currentTab={currentTab()}
-                            forceTruncate={false}
-                            onOverflowChange={setTabsAreOverflowing}
                             onNavigate={(tab, el) => {
                               tabs.select(tab)
                               el?.scrollIntoView({ behavior: "instant", block: "nearest" })

packages/app/test-browser/session-background.test.ts

@@ -0,0 +1,196 @@
+import { describe, expect, test } from "bun:test"
+import type { SessionInfo, SessionMessageAssistantTool, ShellInfo } from "@opencode-ai/client/promise"
+import { createRoot } from "solid-js"
+import { createStore } from "solid-js/store"
+import { createSessionBackground } from "@/session/requests/background"
+
+const tool = (
+  id: string,
+  name: string,
+  metadata: Record<string, string>,
+  input: Record<string, string> = {},
+  status: "completed" | "running" = "completed",
+): SessionMessageAssistantTool => ({
+  id,
+  name,
+  type: "tool",
+  state:
+    status === "running"
+      ? { status, input, metadata }
+      : { status, input, metadata, content: [{ type: "text", text: "backgrounded" }] },
+  time: { created: 0 },
+})
+
+const assistant = (id: string, content: SessionMessageAssistantTool[], completed?: number) => ({
+  id,
+  type: "assistant" as const,
+  agent: "build",
+  model: { id: "model", providerID: "provider" },
+  content,
+  time: { created: 0, completed },
+})
+
+const session = (id: string): SessionInfo => ({
+  id,
+  title: id,
+  parentID: "root",
+  projectID: "project",
+  location: { directory: "/project" },
+  cost: 0,
+  tokens: { input: 0, output: 0, reasoning: 0, cache: { read: 0, write: 0 } },
+  time: { created: 0, updated: 0 },
+})
+
+const shell = (id: string, command: string): ShellInfo => ({
+  id,
+  command,
+  status: "running",
+  cwd: "/project",
+  shell: "sh",
+  file: "output",
+  metadata: { sessionID: "root" },
+  time: { started: 0 },
+})
+
+const notification = (id: string, metadata: Record<string, string>) => ({
+  id,
+  type: "synthetic" as const,
+  text: "complete",
+  metadata,
+  time: { created: 0 },
+})
+
+describe("createSessionBackground", () => {
+  test("excludes completed children and shells using either shell or tool-call IDs", () => {
+    createRoot((dispose) => {
+      const background = createSessionBackground({
+        sessionID: () => "root",
+        messages: () => [
+          notification("before", { source: "subagent", childID: "before-child" }),
+          assistant("assistant", [
+            tool("before-part", "subagent", { status: "running", sessionID: "before-child" }),
+            tool("shell-part", "shell", { status: "running", shellID: "process" }),
+            tool("shell-call", "shell", { status: "running", shellID: "shell-id" }),
+            tool("legacy-call", "shell", { status: "running", shellID: "legacy-shell" }),
+            tool("child-part", "subagent", { status: "running", sessionID: "child" }, { agent: "explore" }),
+          ]),
+          notification("shell-done", { source: "shell", jobID: "shell-part" }),
+          notification("shell-id-done", { source: "shell", shellID: "shell-id" }),
+          notification("legacy-done", { source: "shell", jobID: "legacy-shell" }),
+        ],
+        sessions: () => [],
+        status: () => "idle",
+        shells: () => [],
+      })
+      expect(background.tasks()).toEqual([{ id: "child", type: "subagent", label: "child", agent: "explore" }])
+      dispose()
+    })
+  })
+
+  test("joins live tasks while idle without rescanning history, then switches sessions", () => {
+    createRoot((dispose) => {
+      const [store, setStore] = createStore({
+        id: "root" as string | undefined,
+        messages: [
+          assistant("assistant", [
+            tool("shell-part", "shell", { status: "running", shellID: "shell" }, { command: "old command" }),
+            tool("child-part", "subagent", { status: "running", sessionID: "child" }),
+          ]),
+        ],
+        sessions: [session("live-child"), session("child")],
+        status: { root: "idle", child: "idle", "live-child": "idle" } as Record<string, "idle" | "running">,
+        shells: [{ ...shell("shell", "command"), status: "exited" as ShellInfo["status"] }],
+      })
+      let scans = 0
+      const background = createSessionBackground({
+        sessionID: () => store.id,
+        messages: (id) => {
+          scans += 1
+          return id === "root" ? store.messages : []
+        },
+        sessions: () => store.sessions,
+        status: (id) => store.status[id],
+        shells: () => store.shells,
+      })
+      const blocking = background.blocking()
+      const initial = background.tasks()
+      expect(initial.map((task) => task.id)).toEqual(["child", "shell"])
+
+      setStore("status", { child: "running", "live-child": "running" })
+      expect(background.tasks().map((task) => task.id)).toEqual(["child", "live-child", "shell"])
+      setStore("shells", 0, "status", "running")
+      expect(background.tasks().at(-1)?.label).toBe("command")
+      setStore("sessions", 1, "title", "renamed")
+      expect(background.tasks()[0]?.label).toBe("renamed")
+      setStore("shells", 0, "command", "updated command")
+      const live = background.tasks()
+      expect(live).toEqual([
+        { id: "child", type: "subagent", label: "renamed" },
+        { id: "live-child", type: "subagent", label: "live-child" },
+        { id: "shell", type: "shell", label: "updated command" },
+      ])
+      expect(background.blocking()).toBe(blocking)
+      expect(scans).toBe(1)
+
+      setStore("id", "other")
+      expect(background.tasks()).toEqual([])
+      setStore("id", "root")
+      expect(background.tasks()).toEqual(live)
+      setStore("status", { child: "idle", "live-child": "idle" })
+      setStore("shells", 0, "status", "exited")
+      expect(background.tasks()).toEqual(initial)
+      expect(scans).toBe(3)
+      setStore("id", undefined)
+      expect(background.tasks()).toEqual([])
+      dispose()
+    })
+  })
+
+  test("tracks blocking, backgrounding, and completion through nested store updates", () => {
+    createRoot((dispose) => {
+      const [store, setStore] = createStore({
+        messages: [
+          assistant("earlier", [tool("old-part", "subagent", { sessionID: "old-child" }, {}, "running")]),
+          assistant("current", [
+            tool("child-part", "subagent", { sessionID: "child" }, {}, "running"),
+            tool("shell-part", "shell", {}, { command: "build" }, "running"),
+          ]),
+          assistant("completed", [], 0),
+        ],
+        notification: notification("notice", { source: "subagent", childID: "other-child" }),
+        status: { child: "running", "old-child": "running" } as Record<string, "idle" | "running">,
+      })
+      const messages = store.messages
+      const background = createSessionBackground({
+        sessionID: () => "root",
+        messages: () => [...store.messages, store.notification],
+        sessions: () => [session("child"), session("old-child")],
+        status: (id) => store.status[id],
+        shells: () => [shell("shell", "build")],
+      })
+      expect(background.blocking()).toEqual([
+        { type: "subagent", partID: "child-part", id: "child", label: undefined },
+        { type: "shell", partID: "shell-part", id: undefined, label: "build" },
+      ])
+      expect(background.tasks().map((task) => task.id)).toEqual(["old-child"])
+
+      setStore("messages", 1, "content", 0, "state", {
+        status: "completed",
+        input: { description: "background child" },
+        metadata: { status: "running", sessionID: "child" },
+        content: [{ type: "text", text: "backgrounded" }],
+      })
+      expect(store.messages).toBe(messages)
+      expect(background.blocking().map((task) => task.partID)).toEqual(["shell-part"])
+      setStore("status", "child", "idle")
+      expect(background.tasks().map((task) => task.id)).toEqual(["child", "old-child"])
+      expect(background.tasks()[0]?.label).toBe("background child")
+      setStore("notification", "metadata", "childID", "child")
+      expect(background.tasks().map((task) => task.id)).toEqual(["old-child"])
+      setStore("messages", [0, 1], "time", "completed", 1)
+      expect(background.blocking()).toEqual([])
+      expect(background.tasks().map((task) => task.id)).toEqual(["old-child", "shell"])
+      dispose()
+    })
+  })
+})

packages/app/test-browser/session-resolution.test.ts

@@ -15,8 +15,10 @@ function createFixture(initial: Record<string, Session> = {}) {
   const [cache, setCache] = createSignal(initial)
   const deferred = new Map<string, PromiseWithResolvers<unknown>>()
   const resolves: string[] = []
+  const messages = { syncs: [] as string[], ...Promise.withResolvers<unknown>() }
   return {
     resolves,
+    messages,
     sessions: {
       get: (id: string) => cache()[id],
       sync: (id: string) => {
@@ -25,6 +27,12 @@ function createFixture(initial: Record<string, Session> = {}) {
         deferred.set(id, entry)
         return entry.promise
       },
+      message: {
+        sync: (id: string) => {
+          messages.syncs.push(id)
+          return messages.promise
+        },
+      },
     },
     settle(id: string) {
       setCache({ ...cache(), [id]: sessionOf(id) })
@@ -51,7 +59,34 @@ const flush = async () => {
   await Promise.resolve()
 }
 
-test("resolves an uncached session", async () => {
+test("starts metadata and messages in parallel once the route has a session ID", async () => {
+  await createRoot(async (dispose) => {
+    const fixture = createFixture()
+    const [id, setId] = createSignal<string>()
+    const current = createSessionResolution(id, () => fixture.sessions)
+
+    expect(current()).toBeUndefined()
+    await flush()
+    expect(fixture.resolves).toEqual([])
+    expect(fixture.messages.syncs).toEqual([])
+
+    setId("ses_a")
+    expect(fixture.resolves).toEqual(["ses_a"])
+    expect(fixture.messages.syncs).toEqual(["ses_a"])
+
+    fixture.messages.resolve(undefined)
+    await flush()
+    expect(current()).toBeUndefined()
+
+    fixture.settle("ses_a")
+    await flush()
+    expect(current()?.id).toBe("ses_a")
+
+    dispose()
+  })
+})
+
+test("message failure does not fail metadata resolution", async () => {
   await createRoot(async (dispose) => {
     const fixture = createFixture()
     const current = createSessionResolution(
@@ -59,9 +94,10 @@ test("resolves an uncached session", async () => {
       () => fixture.sessions,
     )
 
-    expect(current()).toBeUndefined()
     await flush()
-    expect(fixture.resolves).toEqual(["ses_a"])
+    fixture.messages.reject(new Error("message sync failed"))
+    await flush()
+    expect(current()).toBeUndefined()
 
     fixture.settle("ses_a")
     await flush()
@@ -82,12 +118,15 @@ test("re-resolves when navigating to an uncached session without a remount", asy
 
     await flush()
     expect(current()?.id).toBe("ses_a")
+    expect(fixture.resolves).toEqual([])
+    expect(fixture.messages.syncs).toEqual(["ses_a"])
 
     expect(() => {
       setId("ses_b")
       current()
     }).not.toThrow()
     expect(fixture.resolves).toEqual(["ses_b"])
+    expect(fixture.messages.syncs).toEqual(["ses_a", "ses_b"])
 
     fixture.settle("ses_b")
     await flush()
@@ -139,6 +178,7 @@ test("returning to a pruned session re-resolves instead of throwing not found",
       current()
     }).not.toThrow()
     expect(fixture.resolves).toEqual(["ses_a", "ses_b", "ses_a"])
+    expect(fixture.messages.syncs).toEqual(["ses_a", "ses_b", "ses_a"])
 
     fixture.settle("ses_a")
     await flush()
@@ -167,6 +207,7 @@ test("revisiting a session whose resolution failed while unfocused retries clean
       current()
     }).not.toThrow()
     expect(fixture.resolves).toEqual(["ses_a", "ses_b", "ses_a"])
+    expect(fixture.messages.syncs).toEqual(["ses_a", "ses_b", "ses_a"])
 
     fixture.settle("ses_a")
     await flush()
@@ -197,6 +238,8 @@ test("re-resolves against a replaced session store", async () => {
     }).not.toThrow()
     await flush()
     expect(second.resolves).toEqual(["ses_a"])
+    expect(first.messages.syncs).toEqual(["ses_a"])
+    expect(second.messages.syncs).toEqual(["ses_a"])
 
     second.settle("ses_a")
     await flush()

packages/app/test-browser/solid-virtual.test.ts

@@ -198,3 +198,41 @@ test("stale pinned indexes do not produce missing virtual items after count shri
     dispose()
   })
 })
+
+test("snapshots materialize only measured rows and restore their current geometry", () => {
+  const options = {
+    count: 100,
+    getItemKey: (index: number) => `row-${index}`,
+    estimateSize: () => 60,
+    getScrollElement: () => null,
+    scrollToFn: () => {},
+    observeElementRect: () => {},
+    observeElementOffset: () => {},
+  }
+  const virtualizer = new Virtualizer<HTMLDivElement, HTMLDivElement>(options)
+  expect(virtualizer.getTotalSize()).toBe(6000)
+  virtualizer.resizeItem(4, 100)
+  virtualizer.resizeItem(99, 140)
+  const measurements = virtualizer.getMeasurements()
+  const reads: number[] = []
+  virtualizer.getMeasurements = () =>
+    new Proxy(measurements, {
+      get(target, key, receiver) {
+        if (typeof key === "string" && /^\d+$/.test(key)) reads.push(Number(key))
+        return Reflect.get(target, key, receiver)
+      },
+    })
+
+  const snapshot = virtualizer.takeSnapshot()
+  expect(reads).toEqual([4, 99])
+  expect(snapshot).toEqual([
+    { index: 4, key: "row-4", start: 240, size: 100, end: 340, lane: 0 },
+    { index: 99, key: "row-99", start: 5980, size: 140, end: 6120, lane: 0 },
+  ])
+  const restored = new Virtualizer<HTMLDivElement, HTMLDivElement>({ ...options, initialMeasurementsCache: snapshot })
+  expect(restored.getTotalSize()).toBe(6120)
+  expect(restored.takeSnapshot()).toEqual(snapshot)
+  restored.setOptions({ ...options, count: 10 })
+  restored.resizeItem(4, 80)
+  expect(restored.takeSnapshot()).toEqual([{ index: 4, key: "row-4", start: 240, size: 80, end: 320, lane: 0 }])
+})

packages/cli/src/commands/commands.ts

@@ -375,6 +375,11 @@ const Root = Spec.make(typeof OPENCODE_CLI_NAME === "string" ? OPENCODE_CLI_NAME
       params: {
         hostname: Flag.string("hostname").pipe(Flag.optional),
         port: Flag.integer("port").pipe(Flag.optional),
+        cors: Flag.string("cors").pipe(
+          Flag.withSchema(Schema.NonEmptyString),
+          Flag.withDescription("Additional allowed CORS origin (repeat for multiple origins)"),
+          Flag.atLeast(0),
+        ),
         service: Flag.boolean("service").pipe(Flag.withDefault(false)),
         stdio: Flag.boolean("stdio").pipe(Flag.withDefault(false)),
       },

packages/cli/src/commands/handlers/serve.ts

@@ -11,6 +11,7 @@ export default Runtime.handler(
       mode: input.service ? "service" : input.stdio ? "stdio" : "default",
       hostname: Option.getOrUndefined(input.hostname),
       port: Option.getOrUndefined(input.port),
+      cors: input.cors.length > 0 ? input.cors : undefined,
     })
   }),
 )

packages/cli/src/server-process.ts

@@ -22,6 +22,7 @@ export type Options = {
   readonly mode: Mode
   readonly hostname?: string
   readonly port?: number
+  readonly cors?: readonly string[]
 }
 
 // The process effect lives until server shutdown; tracing it would parent every request to one process-lifetime trace.
@@ -88,6 +89,7 @@ const processEffect = Effect.fnUntraced(function* (options: Options) {
           },
           hostname,
           port,
+          cors: options.cors ?? config.cors,
           password,
           pty: { handoff },
           simulation: truthy(process.env.OPENCODE_SIMULATE),

packages/cli/src/services/service-config.ts

@@ -15,11 +15,12 @@ export const Info = Schema.Struct({
   hostname: Schema.optional(Schema.String),
   port: Schema.optional(Schema.Int.check(Schema.isGreaterThanOrEqualTo(1), Schema.isLessThanOrEqualTo(65_535))),
   password: Schema.optional(Schema.String),
+  cors: Schema.optional(Schema.Array(Schema.String)),
   env: Schema.optional(Schema.Record(Schema.String, Schema.String)),
 })
 export type Info = typeof Info.Type
 
-const keys = ["hostname", "port", "password", "env"] as const
+const keys = ["hostname", "port", "password", "cors", "env"] as const
 type Key = (typeof keys)[number]
 
 const decodeInfo = Schema.decodeUnknownEffect(Schema.fromJsonString(Info))
@@ -77,7 +78,7 @@ export const migrateConfig = Effect.fnUntraced(function* (legacy: string, file:
 })
 
 function configKey(key: string): Key {
-  if (key === "hostname" || key === "port" || key === "password" || key === "env") return key
+  if (key === "hostname" || key === "port" || key === "password" || key === "cors" || key === "env") return key
   throw new Error(`Unknown service config key: ${key}`)
 }
 
@@ -160,6 +161,9 @@ export const get = Effect.fn("cli.service-config.get")(function* (key?: string,
     case "password": {
       return yield* password()
     }
+    case "cors": {
+      return JSON.stringify((yield* read()).cors ?? [], null, 2)
+    }
     case "env": {
       const env = (yield* read()).env ?? {}
       return name === undefined ? JSON.stringify(env, null, 2) : (env[name] ?? "")
@@ -197,6 +201,19 @@ export const set = Effect.fn("cli.service-config.set")(function* (key: string, v
       yield* write({ ...existing, env: { ...existing.env, [value]: nestedValue } })
       return
     }
+    case "cors": {
+      const cors = value.split(",").map((origin) => origin.trim())
+      if (
+        cors.some((origin) => {
+          const url = URL.parse(origin)
+          return !url || (url.protocol !== "http:" && url.protocol !== "https:") || url.origin !== origin
+        })
+      )
+        throw new Error("CORS must be a comma-separated list of HTTP(S) origins without paths or trailing slashes")
+      yield* Service.stop(yield* options())
+      yield* write({ ...(yield* read()), cors })
+      return
+    }
   }
 })
 
@@ -231,6 +248,12 @@ export const unset = Effect.fn("cli.service-config.unset")(function* (key: strin
       yield* write(Object.keys(env).length === 0 ? rest : { ...rest, env })
       return
     }
+    case "cors": {
+      yield* Service.stop(yield* options())
+      const { cors: _cors, ...next } = yield* read()
+      yield* write(next)
+      return
+    }
   }
 })
 

packages/cli/test/cors.test.ts

@@ -0,0 +1,124 @@
+import { NodeServices } from "@effect/platform-node"
+import { Global } from "@opencode-ai/util/global"
+import { expect, test } from "bun:test"
+import { Effect, Exit, FileSystem } from "effect"
+import { Command } from "effect/unstable/cli"
+import path from "node:path"
+import { Commands } from "../src/commands/commands"
+import { ServiceConfig } from "../src/services/service-config"
+import { it } from "../../core/test/lib/effect"
+
+it.live("service CORS config persists multiple origins and preserves other settings on set and unset", () =>
+  Effect.gen(function* () {
+    const fs = yield* FileSystem.FileSystem
+    const root = yield* fs.makeTempDirectoryScoped({ prefix: "opencode-cors-" })
+    const config = path.join(root, "config")
+    const state = path.join(root, "state")
+    const file = path.join(config, ServiceConfig.filename())
+    const existing = { hostname: "127.0.0.1", port: 4321, password: "test-secret", env: { TEST: "value" } }
+    yield* fs.makeDirectory(config)
+    yield* fs.makeDirectory(state)
+    yield* fs.writeFileString(file, JSON.stringify(existing))
+    yield* Effect.gen(function* () {
+      expect(yield* ServiceConfig.get("cors")).toBe("[]")
+      yield* ServiceConfig.set("cors", " http://192.0.2.10:3001, https://app.example.com ")
+      const cors = ["http://192.0.2.10:3001", "https://app.example.com"]
+      expect(yield* ServiceConfig.read()).toEqual({ ...existing, cors })
+      expect(yield* ServiceConfig.get("cors")).toBe(JSON.stringify(cors, null, 2))
+      expect(JSON.parse(yield* ServiceConfig.get())).toEqual({
+        hostname: existing.hostname,
+        port: existing.port,
+        env: existing.env,
+        cors,
+      })
+      expect(JSON.parse(yield* fs.readFileString(file))).toEqual({ ...existing, cors })
+      yield* ServiceConfig.set("cors", "https://replacement.example.com")
+      expect((yield* ServiceConfig.read()).cors).toEqual(["https://replacement.example.com"])
+      yield* ServiceConfig.unset("cors")
+      expect(yield* ServiceConfig.get("cors")).toBe("[]")
+      expect(JSON.parse(yield* fs.readFileString(file))).toEqual(existing)
+    }).pipe(Effect.provideService(Global.Service, Global.make({ config, state })))
+  }).pipe(Effect.provide(NodeServices.layer)),
+)
+
+it.live("service CORS config rejects empty lists, invalid origins, and extra arguments without changing config", () =>
+  Effect.gen(function* () {
+    const fs = yield* FileSystem.FileSystem
+    const root = yield* fs.makeTempDirectoryScoped({ prefix: "opencode-cors-invalid-" })
+    const config = path.join(root, "config")
+    const state = path.join(root, "state")
+    const file = path.join(config, ServiceConfig.filename())
+    const existing = { port: 4321, cors: ["https://app.example.com"] }
+    yield* fs.makeDirectory(config)
+    yield* fs.makeDirectory(state)
+    yield* fs.writeFileString(file, JSON.stringify(existing))
+    yield* Effect.gen(function* () {
+      yield* Effect.forEach(
+        [
+          "",
+          " ",
+          ",",
+          "https://app.example.com,",
+          ",https://app.example.com",
+          "https://app.example.com,,https://other.example.com",
+          "not-a-url",
+          "*",
+          "null",
+          "ftp://app.example.com",
+          "https://app.example.com/",
+          "https://app.example.com/path",
+          "https://app.example.com?query=1",
+          "https://app.example.com#fragment",
+          "https://user:password@app.example.com",
+        ],
+        (value) =>
+          Effect.gen(function* () {
+            expect(Exit.isFailure(yield* ServiceConfig.set("cors", value).pipe(Effect.exit))).toBe(true)
+            expect(yield* ServiceConfig.read()).toEqual(existing)
+          }),
+      )
+      yield* Effect.forEach(
+        [
+          ServiceConfig.get("cors", "extra"),
+          ServiceConfig.set("cors", "https://app.example.com", "extra"),
+          ServiceConfig.unset("cors", "extra"),
+        ],
+        (operation) =>
+          Effect.gen(function* () {
+            expect(Exit.isFailure(yield* operation.pipe(Effect.exit))).toBe(true)
+          }),
+      )
+      expect(JSON.parse(yield* fs.readFileString(file))).toEqual(existing)
+    }).pipe(Effect.provideService(Global.Service, Global.make({ config, state })))
+  }).pipe(Effect.provide(NodeServices.layer)),
+)
+
+test.each([
+  { args: [], cors: [] },
+  { args: ["--cors", "https://app.example.com"], cors: ["https://app.example.com"] },
+  {
+    args: ["--service", "--cors", "http://192.0.2.10:3001", "--cors", "https://app.example.com"],
+    cors: ["http://192.0.2.10:3001", "https://app.example.com"],
+  },
+])("serve parses CORS flags: $args", async ({ args, cors }) => {
+  const received: (readonly string[])[] = []
+  const command = Commands.commands.serve.spec.pipe(
+    Command.withHandler((input) => Effect.sync(() => void received.push(input.cors))),
+  )
+  await Effect.runPromise(Command.runWith(command, { version: "test" })(args).pipe(Effect.provide(NodeServices.layer)))
+  expect(received).toEqual([cors])
+})
+
+test.each([{ args: ["--cors"] }, { args: ["--cors", ""] }])(
+  "serve rejects a missing or empty CORS flag value: $args",
+  async ({ args }) => {
+    const command = Commands.commands.serve.spec.pipe(Command.withHandler(() => Effect.void))
+    const result = await Effect.runPromise(
+      Command.runWith(command, { version: "test", renderErrors: false })(args).pipe(
+        Effect.exit,
+        Effect.provide(NodeServices.layer),
+      ),
+    )
+    expect(Exit.isFailure(result)).toBe(true)
+  },
+)

packages/cli/test/service.test.ts

@@ -9,6 +9,7 @@ import os from "node:os"
 import path from "node:path"
 import { ServiceConfig } from "../src/services/service-config"
 import { ServiceRegistration } from "../src/services/service-registration"
+import { isolatedEnv } from "./fixture/environment"
 
 test("managed service ports are stable per installation channel", () => {
   expect(ServiceConfig.defaultPort("latest")).toBe(0xc0de)
@@ -313,6 +314,48 @@ test("configured managed service port overrides the channel default", async () =
   }
 }, 30_000)
 
+test.each([
+  { args: [], origins: ["http://192.0.2.10:3001", "https://configured.example.com"] },
+  {
+    args: ["--cors", "http://192.0.2.20:3001", "--cors", "https://override.example.com"],
+    origins: ["http://192.0.2.20:3001", "https://override.example.com"],
+  },
+])(
+  "managed service applies CORS configuration with flag overrides: $args",
+  async ({ args, origins }) => {
+    const root = await fs.mkdtemp(path.join(os.tmpdir(), "opencode-service-cors-"))
+    const config = path.join(root, "config", ServiceConfig.filename())
+    const registration = path.join(root, "state", "opencode", ServiceConfig.filename())
+    const cors = ["http://192.0.2.10:3001", "https://configured.example.com"]
+    await fs.mkdir(path.dirname(config), { recursive: true })
+    await fs.writeFile(config, JSON.stringify({ cors }))
+    const owner = Bun.spawn(
+      [process.execPath, path.join(import.meta.dir, "../src/index.ts"), "serve", "--service", "--port", "0", ...args],
+      { env: isolatedEnv(root), stderr: "pipe", stdout: "ignore" },
+    )
+    try {
+      const info = await waitForInfo(registration)
+      await Promise.all(
+        [...new Set([...cors, ...origins, "https://unlisted.example.com"])].map(async (origin) => {
+          const response = await fetch(new URL("/api/health", info.url), {
+            method: "OPTIONS",
+            headers: { Origin: origin, "Access-Control-Request-Method": "GET" },
+          })
+          expect(response.headers.get("access-control-allow-origin")).toBe(
+            origins.some((value) => value === origin) ? origin : null,
+          )
+        }),
+      )
+      expect((await Bun.file(config).json()).cors).toEqual(cors)
+    } finally {
+      owner.kill("SIGTERM")
+      await owner.exited
+      await fs.rm(root, { recursive: true, force: true })
+    }
+  },
+  30_000,
+)
+
 test("unrelated managed port occupancy reports an actionable conflict", async () => {
   const root = await fs.mkdtemp(path.join(os.tmpdir(), "opencode-service-conflict-"))
   const listener = Bun.serve({ hostname: "127.0.0.1", port: 0, fetch: () => new Response("unrelated") })

packages/client/package.json

@@ -55,6 +55,7 @@
     "@types/bun": "catalog:",
     "@typescript/native-preview": "catalog:",
     "effect": "catalog:",
-    "solid-js": "catalog:"
+    "solid-js": "catalog:",
+    "zod": "catalog:"
   }
 }

packages/client/src/effect/api.ts

@@ -1,5 +1,7 @@
 import type { ModelApi, ProviderApi, WebsearchApi } from "./api/api.js"
 
+export type { RpcApi, RpcClient } from "./rpc.js"
+
 export type * from "./api/api.js"
 
 export type WebSearchApi<E = never> = WebsearchApi<E>

packages/client/src/effect/api/api.ts

@@ -1573,6 +1573,19 @@ export interface SkillApi<E = never> {
   readonly list: SkillListOperation<E>
 }
 
+export type RpcCallInput = {
+  readonly namespace: string
+  readonly method: string
+  readonly location?: { readonly directory?: string | undefined; readonly workspace?: string | undefined } | undefined
+  readonly input?: unknown | undefined
+}
+export type RpcCallOutput = { readonly output?: unknown | undefined }
+export type RpcCallOperation<E = never> = (input: RpcCallInput) => Effect.Effect<RpcCallOutput, E>
+
+export interface RpcApi<E = never> {
+  readonly call: RpcCallOperation<E>
+}
+
 export type EventSubscribeOutput = OpenCodeEvent
 export type EventSubscribeOperation<E = never> = () => Stream.Stream<EventSubscribeOutput, E>
 
@@ -1950,6 +1963,12 @@ export type VcsGetInput = {
 export type VcsGetOutput = { readonly location: Location.Info; readonly data: Vcs.Info }
 export type VcsGetOperation<E = never> = (input?: VcsGetInput) => Effect.Effect<VcsGetOutput, E>
 
+export type VcsBaseInput = {
+  readonly location?: { readonly directory?: string | undefined; readonly workspace?: string | undefined } | undefined
+}
+export type VcsBaseOutput = { readonly location: Location.Info; readonly data: Vcs.Base | null }
+export type VcsBaseOperation<E = never> = (input?: VcsBaseInput) => Effect.Effect<VcsBaseOutput, E>
+
 export type VcsStatusInput = {
   readonly location?: { readonly directory?: string | undefined; readonly workspace?: string | undefined } | undefined
 }
@@ -1967,6 +1986,7 @@ export type VcsBranchesOperation<E = never> = (input?: VcsBranchesInput) => Effe
 export type VcsDiffInput = {
   readonly location?: { readonly directory?: string | undefined; readonly workspace?: string | undefined } | undefined
   readonly mode: Vcs.Mode
+  readonly base?: string | undefined
   readonly context?: number | undefined
 }
 export type VcsDiffOutput = { readonly location: Location.Info; readonly data: ReadonlyArray<FileDiff.Info> }
@@ -1974,6 +1994,7 @@ export type VcsDiffOperation<E = never> = (input: VcsDiffInput) => Effect.Effect
 
 export interface VcsApi<E = never> {
   readonly get: VcsGetOperation<E>
+  readonly base: VcsBaseOperation<E>
   readonly status: VcsStatusOperation<E>
   readonly branches: VcsBranchesOperation<E>
   readonly diff: VcsDiffOperation<E>
@@ -2065,6 +2086,7 @@ export interface AppApi<E = never> {
   readonly file: FileApi<E>
   readonly command: CommandApi<E>
   readonly skill: SkillApi<E>
+  readonly rpc: RpcApi<E>
   readonly event: EventApi<E>
   readonly pty: PtyApi<E>
   readonly experimental: ExperimentalApi<E>

packages/client/src/effect/client.ts

@@ -0,0 +1,58 @@
+export * as OpenCode from "./client.js"
+
+import { Cause, Context, Effect, Stream } from "effect"
+import { HttpClient, HttpClientRequest } from "effect/unstable/http"
+import { SharedEvents } from "../shared-events.js"
+import { ClientError, OpenCode } from "./generated/index.js"
+import { RpcClientRuntime } from "./rpc.js"
+import type { RpcCallOptions } from "../promise/rpc.js"
+
+const CurrentHeaders = Context.Reference<RpcCallOptions["headers"]>("@opencode-ai/client/effect/rpc/headers", {
+  defaultValue: () => undefined,
+})
+
+export const make = Effect.fn("OpenCode.make")(function* (options?: { readonly baseUrl?: URL | string }) {
+  const httpClient = yield* HttpClient.HttpClient
+  const raw = yield* OpenCode.make(options).pipe(
+    Effect.provideService(
+      HttpClient.HttpClient,
+      HttpClient.mapRequestEffect(httpClient, (request) =>
+        Effect.map(CurrentHeaders, (headers) =>
+          headers ? HttpClientRequest.setHeaders(request, new Headers(headers)) : request,
+        ),
+      ),
+    ),
+  )
+  const context = yield* Effect.context()
+  const native = raw.event.subscribe()
+  // Async iterators throw a squashed cause; retain the native typed failures and defects intact.
+  class EventFailure {
+    constructor(readonly cause: Cause.Cause<Stream.Error<typeof native>>) {}
+  }
+  const shared = SharedEvents.make((signal) =>
+    Stream.toAsyncIterableWith(
+      native.pipe(
+        Stream.interruptWhen(RpcClientRuntime.aborted(signal)),
+        Stream.catchCause((cause) => Stream.fail(new EventFailure(cause))),
+      ),
+      context,
+    ),
+  )
+  const subscribe = () =>
+    Stream.fromAsyncIterable(shared.subscribe(), (error) => error).pipe(
+      Stream.catch((error) =>
+        Stream.failCause(error instanceof EventFailure ? error.cause : Cause.fail(new ClientError({ cause: error }))),
+      ),
+    )
+  return {
+    ...raw,
+    event: { ...raw.event, subscribe },
+    rpc: Object.assign(
+      RpcClientRuntime.make(
+        (input, options) => raw.rpc.call(input).pipe(Effect.provideService(CurrentHeaders, options?.headers)),
+        subscribe,
+      ),
+      raw.rpc,
+    ),
+  }
+})

packages/client/src/effect/generated/client.ts

@@ -185,6 +185,8 @@ import type {
   CommandListOutput,
   SkillListInput,
   SkillListOutput,
+  RpcCallInput,
+  RpcCallOutput,
   EventSubscribeOutput,
   PtyListInput,
   PtyListOutput,
@@ -244,6 +246,8 @@ import type {
   WorkspaceDestroyOutput,
   VcsGetInput,
   VcsGetOutput,
+  VcsBaseInput,
+  VcsBaseOutput,
   VcsStatusInput,
   VcsStatusOutput,
   VcsBranchesInput,
@@ -1164,6 +1168,17 @@ const EndpointSkillList = (raw: RawClient["server.skill"]) => (input?: SkillList
 
 const adaptGroupSkill = (raw: RawClient["server.skill"]) => ({ list: EndpointSkillList(raw) })
 
+const EndpointRpcCall = (raw: RawClient["server.rpc"]) => (input: RpcCallInput) =>
+  preserveEffect<RpcCallOutput>()(
+    raw["rpc.call"]({
+      params: { namespace: input["namespace"], method: input["method"] },
+      query: { location: input["location"] },
+      payload: { input: input["input"] },
+    }).pipe(Effect.mapError(mapClientError)),
+  )
+
+const adaptGroupRpc = (raw: RawClient["server.rpc"]) => ({ call: EndpointRpcCall(raw) })
+
 const EndpointEventSubscribe = (raw: RawClient["server.event"]) => () =>
   preserveStream<EventSubscribeOutput>()(
     Stream.unwrap(
@@ -1468,6 +1483,11 @@ const EndpointVcsGet = (raw: RawClient["server.vcs"]) => (input?: VcsGetInput) =
     raw["vcs.get"]({ query: { location: input?.["location"] } }).pipe(Effect.mapError(mapClientError)),
   )
 
+const EndpointVcsBase = (raw: RawClient["server.vcs"]) => (input?: VcsBaseInput) =>
+  preserveEffect<VcsBaseOutput>()(
+    raw["vcs.base"]({ query: { location: input?.["location"] } }).pipe(Effect.mapError(mapClientError)),
+  )
+
 const EndpointVcsStatus = (raw: RawClient["server.vcs"]) => (input?: VcsStatusInput) =>
   preserveEffect<VcsStatusOutput>()(
     raw["vcs.status"]({ query: { location: input?.["location"] } }).pipe(Effect.mapError(mapClientError)),
@@ -1482,13 +1502,14 @@ const EndpointVcsBranches = (raw: RawClient["server.vcs"]) => (input?: VcsBranch
 
 const EndpointVcsDiff = (raw: RawClient["server.vcs"]) => (input: VcsDiffInput) =>
   preserveEffect<VcsDiffOutput>()(
-    raw["vcs.diff"]({ query: { location: input["location"], mode: input["mode"], context: input["context"] } }).pipe(
-      Effect.mapError(mapClientError),
-    ),
+    raw["vcs.diff"]({
+      query: { location: input["location"], mode: input["mode"], base: input["base"], context: input["context"] },
+    }).pipe(Effect.mapError(mapClientError)),
   )
 
 const adaptGroupVcs = (raw: RawClient["server.vcs"]) => ({
   get: EndpointVcsGet(raw),
+  base: EndpointVcsBase(raw),
   status: EndpointVcsStatus(raw),
   branches: EndpointVcsBranches(raw),
   diff: EndpointVcsDiff(raw),
@@ -1556,6 +1577,7 @@ const adaptClient = (raw: RawClient) => ({
   file: adaptGroupFile(raw["server.fs"]),
   command: adaptGroupCommand(raw["server.command"]),
   skill: adaptGroupSkill(raw["server.skill"]),
+  rpc: adaptGroupRpc(raw["server.rpc"]),
   event: adaptGroupEvent(raw["server.event"]),
   pty: adaptGroupPty(raw["server.pty"]),
   experimental: adaptGroupExperimental(raw["server.experimental"]),

packages/client/src/effect/index.ts

@@ -1,8 +1,10 @@
 // TODO: Keep additional network capabilities inside Schema and Protocol as the client grows; /effect must never import
 // Core or Server. Preserve these datatype exports so internal model reorganizations do not require caller migrations.
 import type { Effect } from "effect"
+import type { OpenCode } from "./client.js"
 
 export * from "./generated/index"
+export { OpenCode } from "./client.js"
 export type {
   AgentApi,
   AppApi,
@@ -15,6 +17,8 @@ export type {
   PluginApi,
   ProviderApi,
   ReferenceApi,
+  RpcApi,
+  RpcClient,
   WebSearchApi,
   SessionApi,
   SkillApi,
@@ -34,6 +38,7 @@ export { Permission } from "@opencode-ai/schema/permission"
 export { PermissionSaved } from "@opencode-ai/schema/permission-saved"
 export { Project } from "@opencode-ai/schema/project"
 export { Worktree } from "@opencode-ai/schema/worktree"
+export { Vcs } from "@opencode-ai/schema/vcs"
 export { Provider } from "@opencode-ai/schema/provider"
 export { Pty } from "@opencode-ai/schema/pty"
 export { Question } from "@opencode-ai/schema/question"
@@ -47,4 +52,4 @@ export { Skill } from "@opencode-ai/schema/skill"
 export { Prompt } from "@opencode-ai/schema/prompt"
 export { PromptInput } from "@opencode-ai/schema/prompt-input"
 export type { OpenCodeEvent } from "@opencode-ai/protocol/groups/event"
-export type OpenCodeClient = Effect.Success<ReturnType<typeof import("./generated/client").make>>
+export type OpenCodeClient = Effect.Success<ReturnType<typeof OpenCode.make>>

packages/client/src/effect/rpc.ts

@@ -0,0 +1,94 @@
+export * as RpcClientRuntime from "./rpc.js"
+
+import type { Rpc } from "@opencode-ai/schema/rpc"
+import type { RpcError, RpcInternalError } from "@opencode-ai/protocol/errors"
+import type { OpenCodeEvent } from "@opencode-ai/protocol/groups/event"
+import { Effect, Schema, Stream } from "effect"
+import type { RpcArguments, RpcCallOptions } from "../promise/rpc.js"
+import { RpcRuntime } from "../rpc-runtime.js"
+import type { RpcCallInput, RpcCallOutput } from "./api/api.js"
+
+type RpcEvent = Extract<OpenCodeEvent, { type: `rpc.${string}` }>
+type DecodeError<S> = S extends Schema.Top ? Schema.SchemaError : never
+
+export type RpcClient<
+  D extends Rpc.Definition,
+  E = never,
+  Options = RpcCallOptions,
+  EventError = E,
+> = {
+  readonly [Name in keyof D["methods"]]: (
+    ...args: RpcArguments<Rpc.Input<D["methods"][Name]["input"]>, Options>
+  ) => Effect.Effect<
+    Rpc.Output<D["methods"][Name]["output"]>,
+    Rpc.MethodError<D["methods"][Name]> | DecodeError<D["methods"][Name]["output"]> | E
+  >
+} & {
+  readonly events: {
+    readonly subscribe: <Name extends keyof D["events"] & string>(
+      name: Name,
+    ) => Stream.Stream<Rpc.EventPayload<D, Name>, DecodeError<D["events"][Name]["schema"]> | EventError>
+  }
+}
+
+export interface RpcApi<E = never, Options = RpcCallOptions, EventError = E> {
+  <D extends Rpc.Definition>(definition: D): RpcClient<D, E, Options, EventError>
+}
+
+export function make<CallError, EventError>(
+  call: (input: RpcCallInput, options?: RpcCallOptions) => Effect.Effect<RpcCallOutput, CallError>,
+  subscribe: () => Stream.Stream<OpenCodeEvent, EventError>,
+): RpcApi<Exclude<CallError, RpcError | RpcInternalError> | Rpc.SystemError, RpcCallOptions, EventError> {
+  return <D extends Rpc.Definition>(definition: D) => {
+    const methods = Object.fromEntries(
+      Object.entries(definition.methods).map(([name, method]) => [
+        name,
+        (input?: unknown, options?: RpcCallOptions) => {
+          const result = Effect.gen(function* () {
+            const response = yield* call(
+              {
+                namespace: definition.namespace,
+                method: name,
+                input,
+                location: options?.location,
+              },
+              options,
+            )
+            return yield* RpcRuntime.read(method.output, response.output)
+          }).pipe(Effect.catch((error) => RpcRuntime.readError(method, error)))
+          const signal = options?.signal
+          if (!signal) return result
+          return Effect.suspend(() =>
+            signal.aborted
+              ? Effect.interrupt
+              : Effect.raceFirst(result, Effect.andThen(aborted(signal), Effect.interrupt)),
+          )
+        },
+      ]),
+    )
+    // SAFETY: Every runtime key comes from this definition, and each value is decoded through its corresponding schema.
+    // oxlint-disable-next-line typescript-eslint/no-unsafe-type-assertion
+    return Object.assign(methods, {
+        events: {
+          subscribe: (name: keyof D["events"] & string) => {
+            const type = RpcRuntime.eventType(definition, name)
+            if (!Object.hasOwn(definition.events, name)) return Stream.fail(new Error(`Unknown RPC event: ${type}`))
+            const schema = definition.events[name]
+            return subscribe().pipe(
+              Stream.filter((event): event is RpcEvent => event.type === type),
+              Stream.mapEffect((event) => RpcRuntime.event(definition, name, schema, event)),
+            )
+          },
+      },
+    }) as RpcClient<D, Exclude<CallError, RpcError | RpcInternalError> | Rpc.SystemError, RpcCallOptions, EventError>
+  }
+}
+
+export function aborted(signal: AbortSignal) {
+  return Effect.callback<void>((resume) => {
+    if (signal.aborted) return resume(Effect.void)
+    const abort = () => resume(Effect.void)
+    signal.addEventListener("abort", abort, { once: true })
+    return Effect.sync(() => signal.removeEventListener("abort", abort))
+  })
+}

packages/client/src/promise/api.ts

@@ -1,4 +1,8 @@
-type Client = ReturnType<typeof import("./generated/client.js").make>
+import type { OpenCode } from "./client.js"
+
+type Client = ReturnType<typeof OpenCode.make>
+
+export type { RpcApi, RpcCallOptions, RpcClient, RpcEventPayload } from "./rpc.js"
 
 export type AgentApi = Client["agent"]
 export type CommandApi = Client["command"]

packages/client/src/promise/client.ts

@@ -0,0 +1,18 @@
+export * as OpenCode from "./client.js"
+
+import { SharedEvents } from "../shared-events.js"
+import { OpenCode } from "./generated/index.js"
+import type { ClientOptions } from "./generated/client.js"
+import { makeRpc } from "./rpc.js"
+
+export type { ClientOptions, RequestOptions } from "./generated/client.js"
+
+export function make(options: ClientOptions) {
+  const raw = OpenCode.make(options)
+  const events = SharedEvents.make((signal) => raw.event.subscribe({ signal }))
+  return {
+    ...raw,
+    rpc: Object.assign(makeRpc(raw, events), raw.rpc),
+    event: events,
+  }
+}

packages/client/src/promise/generated/client.ts

@@ -181,6 +181,8 @@ import type {
   CommandListOutput,
   SkillListInput,
   SkillListOutput,
+  RpcCallInput,
+  RpcCallOutput,
   EventSubscribeOutput,
   PtyListInput,
   PtyListOutput,
@@ -240,6 +242,8 @@ import type {
   WorkspaceDestroyOutput,
   VcsGetInput,
   VcsGetOutput,
+  VcsBaseInput,
+  VcsBaseOutput,
   VcsStatusInput,
   VcsStatusOutput,
   VcsBranchesInput,
@@ -1367,7 +1371,7 @@ export function make(options: ClientOptions) {
             method: "GET",
             path: `/api/session/${encodeURIComponent(input.sessionID)}/form`,
             successStatus: 200,
-            declaredStatuses: [404, 400, 401],
+            declaredStatuses: [404, 401, 400],
             empty: false,
           },
           requestOptions,
@@ -1496,7 +1500,7 @@ export function make(options: ClientOptions) {
             method: "GET",
             path: `/api/session/${encodeURIComponent(input.sessionID)}/permission`,
             successStatus: 200,
-            declaredStatuses: [404, 400, 401],
+            declaredStatuses: [404, 401, 400],
             empty: false,
           },
           requestOptions,
@@ -1592,6 +1596,21 @@ export function make(options: ClientOptions) {
           requestOptions,
         ),
     },
+    rpc: {
+      call: (input: RpcCallInput, requestOptions?: RequestOptions) =>
+        request<RpcCallOutput>(
+          {
+            method: "POST",
+            path: `/api/rpc/${encodeURIComponent(input.namespace)}/${encodeURIComponent(input.method)}`,
+            query: { location: input["location"] },
+            body: { input: input["input"] },
+            successStatus: 200,
+            declaredStatuses: [400, 500, 401],
+            empty: false,
+          },
+          requestOptions,
+        ),
+    },
     event: {
       subscribe: (requestOptions?: RequestOptions): AsyncIterable<EventSubscribeOutput> =>
         sse<EventSubscribeOutput>(
@@ -1996,6 +2015,18 @@ export function make(options: ClientOptions) {
           },
           requestOptions,
         ),
+      base: (input?: VcsBaseInput, requestOptions?: RequestOptions) =>
+        request<VcsBaseOutput>(
+          {
+            method: "GET",
+            path: `/api/vcs/base`,
+            query: { location: input?.["location"] },
+            successStatus: 200,
+            declaredStatuses: [503, 401, 400],
+            empty: false,
+          },
+          requestOptions,
+        ),
       status: (input?: VcsStatusInput, requestOptions?: RequestOptions) =>
         request<VcsStatusOutput>(
           {
@@ -2025,9 +2056,9 @@ export function make(options: ClientOptions) {
           {
             method: "GET",
             path: `/api/vcs/diff`,
-            query: { location: input["location"], mode: input["mode"], context: input["context"] },
+            query: { location: input["location"], mode: input["mode"], base: input["base"], context: input["context"] },
             successStatus: 200,
-            declaredStatuses: [401, 400],
+            declaredStatuses: [503, 401, 400],
             empty: false,
           },
           requestOptions,

packages/client/src/promise/generated/types.ts

@@ -333,6 +333,8 @@ export type SkillInfo = {
   content: string
 }
 
+export type RpcOutput = { output?: JsonValue }
+
 export type PermissionReply = "once" | "always" | "reject"
 
 export type Pty = {
@@ -419,6 +421,8 @@ export type WorkspaceDestroyResult = { destroyed: boolean }
 
 export type VcsBranch = { current?: string; default?: string }
 
+export type VcsBase = { name: string; ref: string; source: "reflog" | "default" }
+
 export type VcsFileStatus = {
   file: string
   additions: number
@@ -457,6 +461,15 @@ export type SessionMessageLocationSwitched = {
 
 export type SessionInboxMovePayload = { location: LocationRef; projectID: string; subpath?: string }
 
+export type V2EventRpc = {
+  id: string
+  created: number
+  metadata?: { [x: string]: any } | undefined
+  type: `${"rpc."}${string}`
+  location: LocationRef
+  data: { [x: string]: any }
+}
+
 export type V2EventServerConnected = {
   id: string
   metadata?: { [x: string]: any } | undefined
@@ -2313,6 +2326,7 @@ export type V2Event =
   | VcsBranchUpdated
   | McpStatusChanged
   | McpResourcesChanged
+  | V2EventRpc
   | V2EventServerConnected
 
 export type SessionLogItem = SessionEventDurable | EventLogSynced
@@ -2479,6 +2493,24 @@ export type PermissionNotFoundError = {
 export const isPermissionNotFoundError = (value: unknown): value is PermissionNotFoundError =>
   typeof value === "object" && value !== null && "_tag" in value && value["_tag"] === "PermissionNotFoundError"
 
+export type RpcError = {
+  readonly _tag: "RpcError"
+  readonly type: string
+  readonly message: string
+  readonly data?: unknown | undefined
+}
+export const isRpcError = (value: unknown): value is RpcError =>
+  typeof value === "object" && value !== null && "_tag" in value && value["_tag"] === "RpcError"
+
+export type RpcInternalError = {
+  readonly _tag: "RpcInternalError"
+  readonly type: "rpc.internal"
+  readonly message: string
+  readonly data?: unknown | undefined
+}
+export const isRpcInternalError = (value: unknown): value is RpcInternalError =>
+  typeof value === "object" && value !== null && "_tag" in value && value["_tag"] === "RpcInternalError"
+
 export type PtyNotFoundError = { readonly _tag: "PtyNotFoundError"; readonly ptyID: string; readonly message: string }
 export const isPtyNotFoundError = (value: unknown): value is PtyNotFoundError =>
   typeof value === "object" && value !== null && "_tag" in value && value["_tag"] === "PtyNotFoundError"
@@ -5667,6 +5699,17 @@ export type SkillListOutput = {
   data: Array<SkillInfo>
 }
 
+export type RpcCallInput = {
+  readonly namespace: { readonly namespace: string; readonly method: string }["namespace"]
+  readonly method: { readonly namespace: string; readonly method: string }["method"]
+  readonly location?: {
+    readonly location?: { readonly directory?: string | undefined; readonly workspace?: string | undefined } | undefined
+  }["location"]
+  readonly input?: { readonly input?: JsonValue }["input"]
+}
+
+export type RpcCallOutput = RpcOutput
+
 export type EventSubscribeOutput = V2Event
 
 export type PtyListInput = {
@@ -6073,6 +6116,17 @@ export type VcsGetOutput = {
   data: VcsInfo
 }
 
+export type VcsBaseInput = {
+  readonly location?: {
+    readonly location?: { readonly directory?: string | undefined; readonly workspace?: string | undefined } | undefined
+  }["location"]
+}
+
+export type VcsBaseOutput = {
+  location: { directory: string; workspaceID?: string; project: { id: string; directory: string; canonical: string } }
+  data: VcsBase | null
+}
+
 export type VcsStatusInput = {
   readonly location?: {
     readonly location?: { readonly directory?: string | undefined; readonly workspace?: string | undefined } | undefined
@@ -6110,17 +6164,26 @@ export type VcsBranchesOutput = {
 export type VcsDiffInput = {
   readonly location?: {
     readonly location?: { readonly directory?: string | undefined; readonly workspace?: string | undefined } | undefined
-    readonly mode: "working" | "branch"
+    readonly mode: "working" | "branch" | "committed"
+    readonly base?: string | undefined
     readonly context?: number | undefined
   }["location"]
   readonly mode: {
     readonly location?: { readonly directory?: string | undefined; readonly workspace?: string | undefined } | undefined
-    readonly mode: "working" | "branch"
+    readonly mode: "working" | "branch" | "committed"
+    readonly base?: string | undefined
     readonly context?: number | undefined
   }["mode"]
+  readonly base?: {
+    readonly location?: { readonly directory?: string | undefined; readonly workspace?: string | undefined } | undefined
+    readonly mode: "working" | "branch" | "committed"
+    readonly base?: string | undefined
+    readonly context?: number | undefined
+  }["base"]
   readonly context?: {
     readonly location?: { readonly directory?: string | undefined; readonly workspace?: string | undefined } | undefined
-    readonly mode: "working" | "branch"
+    readonly mode: "working" | "branch" | "committed"
+    readonly base?: string | undefined
     readonly context?: number | undefined
   }["context"]
 }

packages/client/src/promise/index.ts

@@ -1,4 +1,7 @@
+import type { OpenCode } from "./client.js"
+
 export * from "./generated/index.js"
+export { OpenCode } from "./client.js"
 export type {
   AgentApi,
   CatalogApi,
@@ -10,9 +13,13 @@ export type {
   PluginApi,
   ProviderApi,
   ReferenceApi,
+  RpcApi,
+  RpcCallOptions,
+  RpcClient,
+  RpcEventPayload,
   WebSearchApi,
   SessionApi,
   SkillApi,
 } from "./api.js"
 export type { EventSubscribeOutput as OpenCodeEvent } from "./generated/types.js"
-export type OpenCodeClient = ReturnType<typeof import("./generated/client.js").make>
+export type OpenCodeClient = ReturnType<typeof OpenCode.make>

packages/client/src/promise/rpc.ts

@@ -0,0 +1,147 @@
+import type { Rpc } from "@opencode-ai/schema/rpc"
+import type { make, RequestOptions } from "./generated/client.js"
+import { isRpcError, isRpcInternalError } from "./generated/types.js"
+import type { EventSubscribeOutput, LocationGetInput, RpcCallInput } from "./generated/types.js"
+
+type RpcEvent = Extract<EventSubscribeOutput, { type: `rpc.${string}` }>
+
+export interface RpcCallOptions extends RequestOptions {
+  readonly location?: LocationGetInput["location"]
+}
+
+export type RpcArguments<Input, Options> = unknown extends Input
+  ? [input: Input, options?: Options]
+  : undefined extends Input
+    ? [input?: Input, options?: Options]
+    : [input: Input, options?: Options]
+
+export type RpcClient<D extends Rpc.PortableDefinition, Options = RpcCallOptions> = {
+  readonly [Name in keyof D["methods"]]: (
+    ...args: RpcArguments<Rpc.Input<D["methods"][Name]["input"]>, Options>
+  ) => Promise<Rpc.Output<D["methods"][Name]["output"]>>
+} & {
+  readonly events: {
+    readonly subscribe: <Name extends keyof D["events"] & string>(
+      name: Name,
+      options?: Pick<RequestOptions, "signal">,
+    ) => AsyncIterable<RpcEventPayload<D, Name>>
+    readonly on: <Name extends keyof D["events"] & string>(
+      name: Name,
+      handler: (event: RpcEventPayload<D, Name>) => Promise<void> | void,
+      options?: Pick<RequestOptions, "signal">,
+    ) => () => void
+  }
+}
+
+type RpcEventPayloadFor<
+  D extends Rpc.PortableDefinition,
+  Name extends keyof D["events"] & string,
+> = Omit<RpcEvent, "type" | "data"> & {
+  type: `rpc.${D["namespace"]}.${Name}`
+  data: Rpc.EventData<D["events"][Name]["schema"]>
+}
+
+export type RpcEventPayload<
+  D extends Rpc.PortableDefinition,
+  Name extends keyof D["events"] & string = keyof D["events"] & string,
+> = { [K in Name]: RpcEventPayloadFor<D, K> }[Name]
+
+export interface RpcApi<Options = RpcCallOptions> {
+  <D extends Rpc.PortableDefinition>(definition: D): RpcClient<D, Options>
+}
+
+export function makeRpc(
+  raw: ReturnType<typeof make>,
+  events: { subscribe(options?: Pick<RequestOptions, "signal">): AsyncIterable<EventSubscribeOutput> },
+): RpcApi {
+  return (definition) => {
+    const subscribe = (
+      name: string,
+      options?: Pick<RequestOptions, "signal">,
+    ): AsyncIterable<RpcEventPayload<Rpc.PortableDefinition>> => {
+      if (!Object.hasOwn(definition.events, name)) throw new Error(`Unknown RPC event: ${definition.namespace}.${name}`)
+      const type = eventType(definition, name)
+      return {
+        [Symbol.asyncIterator]() {
+          const controller = new AbortController()
+          const signal = options?.signal ? AbortSignal.any([controller.signal, options.signal]) : controller.signal
+          const iterator = (async function* () {
+            try {
+              for await (const published of events.subscribe({ signal })) {
+                if (signal.aborted) return
+                if (published.type !== type) continue
+                // SAFETY: The exact RPC type was selected above; Promise contracts require no client-side transform.
+                // oxlint-disable-next-line typescript-eslint/no-unsafe-type-assertion
+                yield published as RpcEventPayload<Rpc.PortableDefinition>
+              }
+            } catch (error) {
+              if (!signal.aborted) throw error
+            } finally {
+              controller.abort()
+            }
+          })()
+          return {
+            next: () => iterator.next(),
+            return: () => {
+              // Interrupt a pending source read before closing the generator.
+              controller.abort()
+              return iterator.return()
+            },
+          }
+        },
+      }
+    }
+    // SAFETY: Every runtime key comes from this definition's method and event maps, which define RpcClient's mapped keys.
+    // oxlint-disable-next-line typescript-eslint/no-unsafe-type-assertion
+    return Object.assign(
+      Object.fromEntries(
+        Object.keys(definition.methods).map((name) => [
+          name,
+          async (input: unknown, options?: RpcCallOptions) => {
+            try {
+              const result = await raw.rpc.call(
+                {
+                  namespace: definition.namespace,
+                  method: name,
+                  // SAFETY: The method schema defines the accepted input; this assertion bridges it to the generic JSON transport.
+                  // oxlint-disable-next-line typescript-eslint/no-unsafe-type-assertion
+                  input: input as RpcCallInput["input"],
+                  location: options?.location,
+                },
+                { signal: options?.signal, headers: options?.headers },
+              )
+              return result.output
+            } catch (error) {
+              if (!isRpcError(error) && !isRpcInternalError(error)) throw error
+              throw error.data === undefined
+                ? { type: error.type, message: error.message }
+                : { type: error.type, message: error.message, data: error.data }
+            }
+          },
+        ]),
+      ),
+      {
+        events: {
+          subscribe,
+          on: (
+            name: string,
+            handler: (event: RpcEventPayload<Rpc.PortableDefinition>) => Promise<void> | void,
+            options?: Pick<RequestOptions, "signal">,
+          ) => {
+            const controller = new AbortController()
+            const signal = options?.signal ? AbortSignal.any([controller.signal, options.signal]) : controller.signal
+            const source = subscribe(name, { signal })
+            void (async () => {
+              for await (const event of source) await handler(event)
+            })().catch((error: unknown) => console.error(error))
+            return () => controller.abort()
+          },
+        },
+      },
+    ) as RpcClient<typeof definition>
+  }
+}
+
+function eventType(definition: Rpc.PortableDefinition, name: string) {
+  return `rpc.${definition.namespace}.${name}` as const
+}

packages/client/src/rpc-runtime.ts

@@ -0,0 +1,60 @@
+export * as RpcRuntime from "./rpc-runtime.js"
+
+import type { Rpc } from "@opencode-ai/schema/rpc"
+import type { OpenCodeEvent } from "@opencode-ai/protocol/groups/event"
+import { RpcError, RpcInternalError } from "@opencode-ai/protocol/errors"
+import { Effect, Schema } from "effect"
+
+type RpcEvent = Extract<OpenCodeEvent, { type: `rpc.${string}` }>
+
+export function read(schema: Rpc.Method["output"], value: unknown) {
+  // Standard Schema results have already been parsed by the server.
+  return Schema.isSchema(schema) ? Schema.decodeUnknownEffect(schema)(value) : Effect.succeed(value)
+}
+
+export function readError(method: Rpc.Method, error: unknown): Effect.Effect<never, unknown> {
+  if (!(error instanceof RpcError) && !(error instanceof RpcInternalError)) return Effect.fail(error)
+  if (!method.errors || !Object.hasOwn(method.errors, error.type)) {
+    return Effect.fail(
+      error.data === undefined
+        ? { type: error.type, message: error.message }
+        : { type: error.type, message: error.message, data: error.data },
+    )
+  }
+  return read(method.errors[error.type], error.data).pipe(
+    Effect.catch((cause) => Effect.die(cause)),
+    Effect.flatMap((data) =>
+      Effect.fail(
+        data === undefined
+          ? { type: error.type, message: error.message }
+          : { type: error.type, message: error.message, data },
+      ),
+    ),
+  )
+}
+
+export const event = Effect.fn("Client.Rpc.event")(function* <
+  D extends Rpc.Definition,
+  Name extends keyof D["events"] & string,
+>(
+  definition: D,
+  name: Name,
+  schema: Rpc.EventDefinition,
+  event: RpcEvent,
+): Effect.fn.Return<Rpc.EventPayload<D, Name>, unknown> {
+  const data = yield* read(schema.schema, event.data)
+  // SAFETY: The event type was selected by the caller and data was decoded with this event's schema.
+  // oxlint-disable-next-line typescript-eslint/no-unsafe-type-assertion
+  return {
+    ...event,
+    type: eventType(definition, name),
+    data,
+  } as Rpc.EventPayload<D, Name>
+})
+
+export function eventType<const D extends Rpc.Definition, const Name extends keyof D["events"] & string>(
+  definition: D,
+  name: Name,
+): `rpc.${D["namespace"]}.${Name}` {
+  return `rpc.${definition.namespace}.${name}`
+}

packages/client/src/shared-events.ts

@@ -0,0 +1,145 @@
+export * as SharedEvents from "./shared-events.js"
+
+export function make<A extends { readonly type: string }>(connect: (signal: AbortSignal) => AsyncIterable<A>) {
+  type Completion = { readonly error: unknown } | Record<string, never>
+  type Subscriber = {
+    push: (value: A) => Promise<void>
+    finish: (completion: Completion) => void
+  }
+  type Connection = {
+    controller: AbortController
+    subscribers: Set<Subscriber>
+    connected?: A
+    read?: ReturnType<typeof Promise.withResolvers<IteratorResult<A>>>
+  }
+
+  let current: Connection | undefined
+  const delivered = Promise.resolve()
+
+  function stop(connection: Connection) {
+    connection.connected = undefined
+    connection.read?.resolve({ done: true, value: undefined })
+    connection.controller.abort()
+    if (current === connection) current = undefined
+  }
+
+  async function run(connection: Connection) {
+    let iterator: AsyncIterator<A> | undefined
+    let completion: Completion = {}
+    try {
+      if (connection.controller.signal.aborted) return
+      iterator = connect(connection.controller.signal)[Symbol.asyncIterator]()
+      while (!connection.controller.signal.aborted) {
+        // Cancellation must reach return() even when the source has a pending next().
+        connection.read = Promise.withResolvers<IteratorResult<A>>()
+        iterator.next().then(connection.read.resolve, connection.read.reject)
+        const item = await connection.read.promise
+        connection.read = undefined
+        if (item.done || connection.controller.signal.aborted) break
+        if (item.value.type === "server.connected") connection.connected = item.value
+        await Promise.all(Array.from(connection.subscribers, (subscriber) => subscriber.push(item.value)))
+      }
+    } catch (error) {
+      completion = { error }
+    } finally {
+      stop(connection)
+      try {
+        await iterator?.return?.()
+      } catch (error) {
+        if (!("error" in completion)) completion = { error }
+      }
+      connection.subscribers.forEach((subscriber) => subscriber.finish(completion))
+    }
+  }
+
+  return {
+    subscribe(options?: { readonly signal?: AbortSignal }): AsyncIterable<A> {
+      return {
+        [Symbol.asyncIterator]() {
+          const pending: ReturnType<typeof Promise.withResolvers<IteratorResult<A>>>[] = []
+          let started = false
+          let completion: Completion | undefined
+          let connection: Connection | undefined
+          let offered: { readonly value: A; readonly accepted: ReturnType<typeof Promise.withResolvers<void>> } | undefined
+
+          function finish(result: Completion, discard = false) {
+            completion = result
+            if (discard || "error" in result) {
+              offered?.accepted.resolve()
+              offered = undefined
+            }
+            options?.signal?.removeEventListener("abort", abort)
+            if (connection?.subscribers.delete(subscriber) && !connection.subscribers.size) stop(connection)
+            pending.splice(0).forEach((request) => {
+              if ("error" in result) request.reject(result.error)
+              else request.resolve({ done: true, value: undefined })
+            })
+          }
+
+          function abort() {
+            finish({}, true)
+          }
+
+          const subscriber: Subscriber = {
+            finish,
+            push(value) {
+              if (completion) return delivered
+              const request = pending.shift()
+              if (request) {
+                request.resolve({ done: false, value })
+                return delivered
+              }
+              const accepted = Promise.withResolvers<void>()
+              offered = { value, accepted }
+              return accepted.promise
+            },
+          }
+
+          function start() {
+            if (completion) return
+            const fresh = !current
+            connection = current ?? {
+              controller: new AbortController(),
+              subscribers: new Set<Subscriber>(),
+            }
+            current = connection
+            connection.subscribers.add(subscriber)
+            if (connection.connected) void subscriber.push(connection.connected)
+            if (fresh) void run(connection)
+          }
+
+          return {
+            next(): Promise<IteratorResult<A>> {
+              if (offered) {
+                const current = offered
+                offered = undefined
+                current.accepted.resolve()
+                return Promise.resolve({ done: false, value: current.value })
+              }
+              if (completion) {
+                if ("error" in completion) return Promise.reject(completion.error)
+                return Promise.resolve({ done: true, value: undefined })
+              }
+              if (options?.signal?.aborted) {
+                abort()
+                return Promise.resolve({ done: true, value: undefined })
+              }
+              const request = Promise.withResolvers<IteratorResult<A>>()
+              pending.push(request)
+              if (!started) {
+                started = true
+                options?.signal?.addEventListener("abort", abort, { once: true })
+                start()
+              }
+              return request.promise
+            },
+            return(): Promise<IteratorResult<A>> {
+              finish({}, true)
+              return Promise.resolve({ done: true, value: undefined })
+            },
+          }
+        },
+      }
+    },
+  }
+}

packages/client/src/solid/connection.ts

@@ -93,7 +93,7 @@ export function createClientConnection(initialApi: OpenCodeClient, options: Clie
         const event = await iterator.next()
         if (signal.aborted) return { error: undefined, connectedAt }
         if (event.done) return { error: new Error("Event stream disconnected"), connectedAt }
-        if ("durable" in event.value)
+        if ("durable" in event.value && event.value.durable)
           options.log?.debug?.("event", {
             type: event.value.type,
             aggregateID: event.value.durable.aggregateID,

packages/client/src/solid/data.ts

@@ -29,6 +29,7 @@ import type {
   SessionMessageAssistantTool,
   SessionInfo,
   SessionInboxInfo,
+  SessionInboxCompaction,
   ShellInfo,
   SkillInfo,
   VcsInfo,
@@ -50,6 +51,7 @@ import type { SessionInbox } from "@opencode-ai/schema/session-inbox"
 import { batch, createEffect, createMemo, createSignal, onCleanup } from "solid-js"
 
 export type DataSessionStatus = "idle" | "running"
+type OpenCodeEventMap = { [Type in OpenCodeEvent["type"]]: Extract<OpenCodeEvent, { type: Type }> }
 
 export type CreateDataInput = {
   readonly api: () => OpenCodeClient
@@ -57,7 +59,7 @@ export type CreateDataInput = {
   readonly event: {
     readonly on: <Type extends OpenCodeEvent["type"]>(
       type: Type,
-      handler: (event: Extract<OpenCodeEvent, { type: Type }>) => void,
+      handler: (event: OpenCodeEventMap[Type]) => void,
     ) => () => void
     readonly listen: (handler: (event: { name: OpenCodeEvent["type"]; details: OpenCodeEvent }) => void) => () => void
   }
@@ -284,12 +286,11 @@ export function createData(config: CreateDataInput) {
     setStore("session", "pending", sessionID, index, { ...item, delivery })
   }
 
-  // Inbox IDs of optimistic prompt admissions still awaiting their durable
-  // echo. This is the one deliberate piece of in-flight bookkeeping in this
-  // layer: it exists so a rejection only rolls back rows the server never
-  // acknowledged, and so a concurrent pending re-fetch cannot wipe a row the
-  // server does not know about yet. Entries clear on the enqueued echo or on
-  // rollback — not on POST success, which typically precedes the echo.
+  // Inbox IDs of optimistic admissions awaiting acknowledgement, so rejection
+  // only rolls back unacknowledged rows and a pending re-fetch cannot wipe a
+  // row the server does not know about yet. Prompts clear on their durable
+  // echo, positive pending read, or rollback; compactions also reconcile the
+  // POST's canonical ID.
   const outbox = new Set<string>()
 
   // Session IDs of optimistic create admissions still awaiting acknowledgement
@@ -303,11 +304,13 @@ export function createData(config: CreateDataInput) {
   // to exist server-side instead of failing with "not found".
   const creating = new Map<string, Promise<unknown>>()
 
-  // Per-session send chain: prompts must be admitted in submission order,
-  // and HTTP gives no ordering across concurrent POSTs. Each prompt waits
-  // for the previous prompt's POST (settled, so one failure does not block
-  // the next) before sending its own.
+  // Per-session send chain: prompts and compactions must be admitted in
+  // submission order. Each waits for the previous POST to settle, so one
+  // failure does not block the next.
   const sending = new Map<string, Promise<unknown>>()
+  const messageLoads = new Map<string, Promise<unknown>>()
+  const compacting = new Map<string, { id: string; observed: Set<string>; request: Promise<SessionInboxCompaction> }>()
+  onCleanup(() => compacting.clear())
 
   // Register `promise` under `key` until it settles. A later registration
   // replaces an earlier one; settlement only clears its own entry.
@@ -319,9 +322,24 @@ export function createData(config: CreateDataInput) {
     void promise.then(settle, settle)
   }
 
+  // Capture creation before settlement clears its entry, so dependent RPCs still see a failed create.
+  function sendAdmission<Value>(sessionID: string, send: () => Promise<Value>, gate?: Promise<unknown>) {
+    const created = creating.get(sessionID)
+    const previous = sending.get(sessionID)
+    const request = Promise.resolve()
+      .then(() => Promise.all([gate, created, previous]))
+      .then(send)
+    track(
+      sending,
+      sessionID,
+      request.catch(() => undefined),
+    )
+    return request
+  }
+
   // Upsert an admitted inbox item into pending, input, and (for user and
   // synthetic items) the visible transcript. Used by the inbox.enqueued
-  // handler and by optimistic prompt admission; the upsert is what reconciles
+  // handler and by optimistic admission; the upsert is what reconciles
   // the durable echo with an optimistic placeholder — the durable payload and
   // times replace the client's guess.
   function admitLocal(item: SessionInboxInfo) {
@@ -334,6 +352,7 @@ export function createData(config: CreateDataInput) {
         item.sessionID,
         at < 0 ? [...pending, item] : pending.map((entry, index) => (index === at ? item : entry)),
       )
+      if (item.type === "compaction") return
       const input = store.session.input[item.sessionID] ?? []
       if (!input.includes(item.id)) setStore("session", "input", item.sessionID, [...input, item.id])
       materializeInboxMessage(item)
@@ -668,6 +687,7 @@ export function createData(config: CreateDataInput) {
           draft.push(existing)
           message.reindex(draft, index, position)
         })
+        compacting.get(event.data.sessionID)?.observed.add(event.data.inboxID)
         return
       }
       case "session.inbox.delivery.changed":
@@ -675,6 +695,7 @@ export function createData(config: CreateDataInput) {
         return
       case "session.inbox.cancelled": {
         retractLocal(event.data.sessionID, event.data.inboxID)
+        compacting.get(event.data.sessionID)?.observed.add(event.data.inboxID)
         return
       }
       case "session.inbox.enqueued": {
@@ -685,6 +706,12 @@ export function createData(config: CreateDataInput) {
           timeCreated: event.created,
           ...event.data.item,
         })
+        if (event.data.item.type === "compaction") {
+          const active = compacting.get(event.data.sessionID)
+          active?.observed.add(event.data.inboxID)
+          if (active && active.id !== event.data.inboxID && outbox.delete(active.id))
+            removePending(event.data.sessionID, active.id)
+        }
         return
       }
       case "session.instructions.updated":
@@ -724,7 +751,8 @@ export function createData(config: CreateDataInput) {
             command: event.data.shell.command,
             status: event.data.shell.status,
             exit: event.data.shell.exit,
-            metadata: event.metadata,
+            metadata:
+              event.data.shell.metadata.background === true ? { ...event.metadata, background: true } : event.metadata,
             time: { created: event.created },
           })
         })
@@ -983,6 +1011,7 @@ export function createData(config: CreateDataInput) {
             time: { created: event.created },
           })
         })
+        if (event.data.inputID) compacting.get(event.data.sessionID)?.observed.add(event.data.inputID)
         return
       case "session.execution.succeeded":
       case "session.execution.failed":
@@ -1080,6 +1109,7 @@ export function createData(config: CreateDataInput) {
           }
           message.append(draft, index, failed)
         })
+        if (event.data.inputID) compacting.get(event.data.sessionID)?.observed.add(event.data.inputID)
         return
       case "permission.asked":
         if (store.session.permission[event.data.sessionID]?.some((request) => request.id === event.data.id)) return
@@ -1266,12 +1296,17 @@ export function createData(config: CreateDataInput) {
         sync(sessionID: string) {
           return sync.run(`session.pending:${sessionID}`, async () => {
             const pending = await api().session.inbox.list({ sessionID })
+            // A positive read acknowledges admission even when its SSE echo is delayed.
+            pending.forEach((item) => outbox.delete(item.id))
+            // Compactions also coalesce by Session, not just by the proposed ID.
+            if (pending.some((item) => item.type === "compaction"))
+              store.session.pending[sessionID]
+                ?.filter((item) => item.type === "compaction")
+                .forEach((item) => outbox.delete(item.id))
             // Keep optimistic rows still awaiting their echo: this fetch may
             // have raced ahead of an in-flight admission the server does not
             // know about yet.
-            const inflight = (store.session.pending[sessionID] ?? []).filter(
-              (item) => outbox.has(item.id) && !pending.some((row) => row.id === item.id),
-            )
+            const inflight = (store.session.pending[sessionID] ?? []).filter((item) => outbox.has(item.id))
             const merged = inflight.length === 0 ? pending : [...pending, ...inflight]
             batch(() => {
               setStore("session", "pending", sessionID, reconcile(merged))
@@ -1345,13 +1380,56 @@ export function createData(config: CreateDataInput) {
         if (fresh) track(creating, id, request)
         return { id, request }
       },
+      compact(input: { sessionID: string; model?: ModelRef }) {
+        const active = compacting.get(input.sessionID)
+        if (active) return active.request
+        // A known pending control ID may be consumed while setup waits. Propose
+        // a fresh ID and let the server coalesce, without duplicating its row.
+        const id = SessionMessage.ID.create()
+        if (!store.session.pending[input.sessionID]?.some((item) => item.type === "compaction")) {
+          outbox.add(id)
+          admitLocal({
+            id,
+            sessionID: input.sessionID,
+            timeCreated: Date.now(),
+            type: "compaction",
+            delivery: "steer",
+            payload: {},
+          })
+        }
+        // Compaction admission can coalesce onto a different ID. Retire the
+        // speculative row on an echo, and remember consumed IDs until the POST
+        // settles so its older response cannot resurrect a queued row.
+        const observed = new Set<string>()
+        const request = sendAdmission(input.sessionID, async () => {
+          if (input.model) await api().session.switchModel({ sessionID: input.sessionID, model: input.model })
+          return api().session.compact({ sessionID: input.sessionID, id })
+        })
+          .then((item) => {
+            batch(() => {
+              outbox.delete(id)
+              if (item.id !== id) removePending(input.sessionID, id)
+              if (!observed.has(item.id) && !messageIndex.get(input.sessionID)?.has(item.id)) admitLocal(item)
+            })
+            return item
+          })
+          .catch((error) => {
+            if (outbox.delete(id)) removePending(input.sessionID, id)
+            throw error
+          })
+          .finally(() => {
+            if (compacting.get(input.sessionID)?.request === request) compacting.delete(input.sessionID)
+          })
+        compacting.set(input.sessionID, { id, observed, request })
+        return request
+      },
       // Optimistic prompt admission: render the prompt immediately under a
       // client-minted ID, send it, and let the durable inbox.enqueued echo
       // upsert that same ID with the server's payload. Server admission is
       // idempotent per ID, so retrying with the identical payload cannot
       // double-admit.
-      prompt(input: SessionPromptInput & { gate?: Promise<unknown> }) {
-        const { gate, ...request } = input
+      prompt(input: SessionPromptInput & { gate?: Promise<unknown>; prepare?: () => Promise<unknown> }) {
+        const { gate, prepare, ...request } = input
         const id = request.id ?? SessionMessage.ID.create()
         // A retry may reuse an ID that is already rendered — and possibly
         // already durable. Admit optimistically only for new IDs so a failed
@@ -1377,25 +1455,15 @@ export function createData(config: CreateDataInput) {
             },
           })
         }
-        // Wrapped so even a synchronous client failure reaches the rollback.
-        // The POST additionally waits for the caller's gate, for any
-        // in-flight optimistic create of this session, and for the previous
-        // prompt's POST: the row renders now, the send happens once the
-        // session exists server-side and earlier prompts are admitted.
-        const previous = sending.get(request.sessionID)
-        const send = Promise.resolve()
-          .then(() => Promise.all([gate, creating.get(request.sessionID), previous]))
-          .then(() => api().session.prompt({ ...request, id }))
-        track(
-          sending,
+        return sendAdmission(
           request.sessionID,
-          send.then(
-            () => undefined,
-            () => undefined,
-          ),
-        )
-        return send.catch((error) => {
-          // Roll back only rows this call admitted and the echo has not
+          async () => {
+            await prepare?.()
+            return api().session.prompt({ ...request, id })
+          },
+          gate,
+        ).catch((error) => {
+          // Roll back only rows this call admitted and the server has not
           // acknowledged: anything else is server state.
           if (fresh && outbox.delete(id)) retractLocal(request.sessionID, id)
           throw error
@@ -1464,20 +1532,70 @@ export function createData(config: CreateDataInput) {
         loading(sessionID: string) {
           return store.session.messageLoading[sessionID] ?? false
         },
-        async loadMore(sessionID: string) {
+        async loadMore(
+          sessionID: string,
+          options?: {
+            all?: boolean
+            signal?: AbortSignal
+            /** Runs synchronously inside the store-publication batch. */
+            beforePublish?: () => void
+          },
+        ) {
+          const signal = options?.signal
+          if (signal?.aborted) return
+          while (messageLoads.has(sessionID)) {
+            const published = await (() => {
+              const pending = messageLoads.get(sessionID)
+              if (!signal) return pending
+              const aborted = Promise.withResolvers<void>()
+              const cancel = () => aborted.resolve()
+              signal.addEventListener("abort", cancel, { once: true })
+              return Promise.race([pending, aborted.promise])
+                .catch((error) => {
+                  if (!signal.aborted) throw error
+                })
+                .finally(() => signal.removeEventListener("abort", cancel))
+            })()
+            if ((!options?.all && published) || signal?.aborted) return
+          }
           const cursor = store.session.messageCursor[sessionID]
-          if (!cursor || store.session.messageLoading[sessionID]) return
+          if (!cursor || signal?.aborted) return
           setStore("session", "messageLoading", sessionID, true)
-          const response = await api()
-            .message.list({ sessionID, limit: messagePageLimit, cursor })
+          const request = (async () => {
+            const fetched: SessionMessageInfo[] = []
+            let next: string | undefined = cursor
+            do {
+              const response = await api().message.list(
+                {
+                  sessionID,
+                  limit: options?.all ? 200 : messagePageLimit,
+                  cursor: next,
+                },
+                { signal },
+              )
+              if (signal?.aborted) return
+              fetched.push(...response.data)
+              next = response.cursor.next ?? undefined
+              if (!options?.all) break
+            } while (next)
+            // A jump through history publishes once, not once per page of offscreen messages.
+            const existing = store.session.message[sessionID] ?? []
+            const ids = new Set(existing.map((item) => item.id))
+            const messages = [...fetched.reverse().filter((item) => !ids.has(item.id)), ...existing]
+            batch(() => {
+              options?.beforePublish?.()
+              messageIndex.set(sessionID, new Map(messages.map((item, position) => [item.id, position])))
+              setStore("session", "message", sessionID, reconcile(messages))
+              setStore("session", "messageCursor", sessionID, next)
+            })
+            return true
+          })()
+            .catch((error) => {
+              if (!signal?.aborted) throw error
+            })
             .finally(() => setStore("session", "messageLoading", sessionID, false))
-          const older = response.data.toReversed()
-          const existing = store.session.message[sessionID] ?? []
-          const ids = new Set(existing.map((item) => item.id))
-          const messages = [...older.filter((item) => !ids.has(item.id)), ...existing]
-          messageIndex.set(sessionID, new Map(messages.map((item, position) => [item.id, position])))
-          setStore("session", "message", sessionID, reconcile(messages))
-          setStore("session", "messageCursor", sessionID, response.cursor.next ?? undefined)
+          track(messageLoads, sessionID, request)
+          await request
         },
         invalidate(sessionID: string) {
           sync.invalidate(`session.message:${sessionID}`)

packages/client/test/api.types.ts

@@ -45,6 +45,7 @@ const promiseRemove: Promise<void> = promiseClient.session.instructions.entry.re
   sessionID: "ses_test",
   key: "review-notes",
 })
+const emptyRpcOutput: Awaited<ReturnType<typeof promiseClient.rpc.call>> = {}
 
 void [
   effectSession,
@@ -54,6 +55,7 @@ void [
   promiseList,
   promisePut,
   promiseRemove,
+  emptyRpcOutput,
   exactVersion,
   compatibleVersion,
 ]

packages/client/test/contract-identity.test.ts

@@ -6,6 +6,7 @@ import { Model } from "@opencode-ai/schema/model"
 import { Prompt } from "@opencode-ai/schema/prompt"
 import { Session } from "@opencode-ai/schema/session"
 import { SessionMessage } from "@opencode-ai/schema/session-message"
+import { Vcs } from "@opencode-ai/schema/vcs"
 
 const Client = await import("../src/effect")
 
@@ -14,6 +15,7 @@ test("effect entrypoint exposes canonical Schema contracts", () => {
   expect(Client.Config).toBe(Config)
   expect(Client.Model).toBe(Model)
   expect(Client.Session).toBe(Session)
+  expect(Client.Vcs.Base).toBe(Vcs.Base)
 })
 
 test("generated Effect API names canonical and composed outputs", async () => {

packages/client/test/effect.test.ts

@@ -27,6 +27,26 @@ test("health.get decodes the readiness response", async () => {
   expect(result).toEqual({ healthy: true, version: "old", pid: 123 })
 })
 
+test("vcs.base decodes nullable review-base metadata", async () => {
+  const location = { directory: "/repo", project: { id: "global", directory: "/repo", canonical: "/repo" } }
+  const base = {
+    name: "release",
+    ref: "refs/remotes/origin/release",
+    source: "reflog",
+  }
+  for (const data of [base, null]) {
+    const httpClient = HttpClient.make((request) =>
+      Effect.succeed(HttpClientResponse.fromWeb(request, Response.json({ location, data }))),
+    )
+    const result = await Effect.gen(function* () {
+      const client = yield* OpenCode.make({ baseUrl: "http://localhost:3000" })
+      return yield* client.vcs.base({ location: { directory: AbsolutePath.make("/repo") } })
+    }).pipe(Effect.provideService(HttpClient.HttpClient, httpClient), Effect.runPromise)
+    expect(result.data).toEqual(data)
+    expect(result.location.directory).toBe("/repo")
+  }
+})
+
 test("session.get returns the decoded Effect projection", async () => {
   const httpClient = HttpClient.make((request) =>
     Effect.succeed(HttpClientResponse.fromWeb(request, Response.json(session))),

packages/client/test/import-boundaries.test.ts

@@ -14,34 +14,34 @@ describe("public import boundaries", () => {
   test("isolates each public entrypoint", async () => {
     const root = await bundleInputs("@opencode-ai/client", "browser")
 
-    expect(within(root, effect)).toEqual([])
-    expect(within(root, schema)).toEqual([])
-    expect(within(root, protocol)).toEqual([])
-    expect(within(root, core)).toEqual([])
-    expect(within(root, server)).toEqual([])
+    expect(within(root.all, effect)).toEqual([])
+    expect(within(root.all, schema)).toEqual([])
+    expect(within(root.all, protocol)).toEqual([])
+    expect(within(root.all, core)).toEqual([])
+    expect(within(root.all, server)).toEqual([])
 
     const network = await bundleInputs("@opencode-ai/client/effect", "browser")
 
-    expect(within(network, effect).length).toBeGreaterThan(0)
-    expect(within(network, schema).length).toBeGreaterThan(0)
-    expect(within(network, protocol).length).toBeGreaterThan(0)
-    expect(within(network, core)).toEqual([])
-    expect(within(network, server)).toEqual([])
+    expect(within(network.eager, effect).length).toBeGreaterThan(0)
+    expect(within(network.eager, schema).length).toBeGreaterThan(0)
+    expect(within(network.eager, protocol).length).toBeGreaterThan(0)
+    expect(within(network.all, core)).toEqual([])
+    expect(within(network.all, server)).toEqual([])
 
     const promiseService = await bundleInputs("@opencode-ai/client/service", "bun")
 
-    expect(within(promiseService, effect)).toEqual([])
-    expect(within(promiseService, schema)).toEqual([])
-    expect(within(promiseService, protocol)).toEqual([])
-    expect(within(promiseService, core)).toEqual([])
-    expect(within(promiseService, server)).toEqual([])
+    expect(within(promiseService.all, effect)).toEqual([])
+    expect(within(promiseService.all, schema)).toEqual([])
+    expect(within(promiseService.all, protocol)).toEqual([])
+    expect(within(promiseService.all, core)).toEqual([])
+    expect(within(promiseService.all, server)).toEqual([])
 
     const effectService = await bundleInputs("@opencode-ai/client/effect/service", "bun")
 
-    expect(within(effectService, effect).length).toBeGreaterThan(0)
-    expect(within(effectService, protocol).length).toBeGreaterThan(0)
-    expect(within(effectService, core)).toEqual([])
-    expect(within(effectService, server)).toEqual([])
+    expect(within(effectService.eager, effect).length).toBeGreaterThan(0)
+    expect(within(effectService.eager, protocol).length).toBeGreaterThan(0)
+    expect(within(effectService.all, core)).toEqual([])
+    expect(within(effectService.all, server)).toEqual([])
   })
 })
 
@@ -70,8 +70,21 @@ async function bundleInputs(specifier: string, target: "browser" | "bun") {
       new Response(child.stderr).text(),
     ])
     if (exitCode !== 0) throw new Error(stdout + stderr)
-    const metadata = await Bun.file(metafile).json()
-    return Object.keys(metadata.inputs).map((input) => resolve(directory, input))
+    const metadata: {
+      inputs: Record<string, { imports: Array<{ path: string; kind: string; external?: boolean }> }>
+    } = await Bun.file(metafile).json()
+    const inputs = new Map(Object.entries(metadata.inputs).map(([file, input]) => [resolve(directory, file), input]))
+    const eager = new Set<string>()
+    const visit = (file: string) => {
+      if (eager.has(file)) return
+      eager.add(file)
+      inputs
+        .get(file)
+        ?.imports.filter((input) => !input.external && input.kind !== "dynamic-import")
+        .forEach((input) => visit(resolve(directory, input.path)))
+    }
+    visit(entrypoint)
+    return { all: Array.from(inputs.keys()), eager: Array.from(eager) }
   } finally {
     await rm(temporary, { recursive: true, force: true })
   }

packages/client/test/promise.test.ts

@@ -24,6 +24,7 @@ test("exposes every standard HTTP API group", () => {
     "file",
     "command",
     "skill",
+    "rpc",
     "event",
     "pty",
     "experimental",
@@ -47,7 +48,7 @@ test("exposes every standard HTTP API group", () => {
   expect(Object.keys(client.integration.command)).toEqual(["connect", "status", "cancel"])
   expect(Object.keys(client.websearch)).toEqual(["providers", "query"])
   expect(Object.keys(client.file)).toEqual(["read", "list", "find"])
-  expect(Object.keys(client.vcs)).toEqual(["get", "status", "branches", "diff"])
+  expect(Object.keys(client.vcs)).toEqual(["get", "base", "status", "branches", "diff"])
   expect(Object.keys(client.pty)).toEqual(["list", "create", "get", "update", "remove", "connect"])
   expect(Object.keys(client.pty.connect)).toEqual(["token"])
   expect(Object.keys(client.experimental)).toEqual(["persistentPty"])
@@ -84,6 +85,46 @@ test("config.get returns ordered config entries for a location", async () => {
   expect(request?.url).toBe("http://localhost:3000/api/config?location%5Bdirectory%5D=%2Ftmp%2Fproject")
 })
 
+test("vcs.base and committed diffs preserve location and explicit base on the wire", async () => {
+  const requests: Request[] = []
+  const location = { directory: "/repo", project: { id: "global", directory: "/repo", canonical: "/repo" } }
+  const base = { name: "release", ref: "refs/remotes/origin/release", source: "reflog" }
+  const client = OpenCode.make({
+    baseUrl: "http://localhost:3000",
+    fetch: async (input, init) => {
+      const request = input instanceof Request ? input : new Request(input, init)
+      requests.push(request)
+      return Response.json({ location, data: new URL(request.url).pathname.endsWith("/base") ? base : [] })
+    },
+  })
+  expect(await client.vcs.base({ location: { directory: "/repo" } })).toEqual({ location, data: base })
+  expect(
+    await client.vcs.diff({ location: { directory: "/repo" }, mode: "committed", base: base.ref, context: 1 }),
+  ).toEqual({ location, data: [] })
+  expect(new URL(requests[0].url).pathname).toBe("/api/vcs/base")
+  const query = new URL(requests[1].url).searchParams
+  expect(query.get("location[directory]")).toBe("/repo")
+  expect(query.get("mode")).toBe("committed")
+  expect(query.get("base")).toBe(base.ref)
+  expect(query.get("context")).toBe("1")
+})
+
+test("vcs.diff exposes unavailable comparisons as errors, not empty diffs", async () => {
+  const client = OpenCode.make({
+    baseUrl: "http://localhost:3000",
+    fetch: async () =>
+      Response.json(
+        { _tag: "ServiceUnavailableError", service: "vcs", message: "No review base available" },
+        { status: 503 },
+      ),
+  })
+  await expect(client.vcs.diff({ mode: "committed" })).rejects.toMatchObject({
+    _tag: "ServiceUnavailableError",
+    service: "vcs",
+    message: "No review base available",
+  })
+})
+
 test("project.update uses the global project contract", async () => {
   let request: Request | undefined
   const project = {
@@ -637,6 +678,51 @@ test("event.subscribe terminates on malformed Promise SSE data", async () => {
   })
 })
 
+test("native event signals cancel only their listener and close transport after the last listener", async () => {
+  const opened = Promise.withResolvers<Request>()
+  const client = OpenCode.make({
+    baseUrl: "http://localhost:3000",
+    headers: { authorization: "Bearer events" },
+    fetch: async (input, init) => {
+      const request = new Request(input, init)
+      opened.resolve(request)
+      return new Response(
+        new ReadableStream({
+          start(controller) {
+            request.signal.addEventListener("abort", () => controller.error(request.signal.reason), { once: true })
+          },
+        }),
+        { headers: { "content-type": "text/event-stream" } },
+      )
+    },
+  })
+  const first = new AbortController()
+  const second = new AbortController()
+  const one = client.event.subscribe({ signal: first.signal })[Symbol.asyncIterator]().next()
+  const two = client.event.subscribe({ signal: second.signal })[Symbol.asyncIterator]().next()
+  const request = await opened.promise
+  expect(request.headers.get("authorization")).toBe("Bearer events")
+  first.abort()
+  expect((await one).done).toBe(true)
+  expect(request.signal.aborted).toBe(false)
+  second.abort()
+  expect((await two).done).toBe(true)
+  expect(request.signal.aborted).toBe(true)
+})
+
+test("native pre-aborted event signals do not open a transport", async () => {
+  let requests = 0
+  const client = OpenCode.make({
+    baseUrl: "http://localhost:3000",
+    fetch: async () => {
+      requests++
+      return new Response(null)
+    },
+  })
+  expect((await client.event.subscribe({ signal: AbortSignal.abort() })[Symbol.asyncIterator]().next()).done).toBe(true)
+  expect(requests).toBe(0)
+})
+
 test("event.subscribe accepts a fragmented SSE event below the size limit", async () => {
   const event = { id: "evt_large", type: "test.large", data: { output: "x".repeat(12 * 1024 * 1024) } }
   const encoded = new TextEncoder().encode(`data: ${JSON.stringify(event)}\n\n`)

packages/client/test/rpc-effect.test.ts

@@ -0,0 +1,495 @@
+import { expect, test } from "bun:test"
+import { Rpc } from "@opencode-ai/schema/rpc"
+import { Cause, Context, Effect, Exit, Fiber, Schema, Stream } from "effect"
+import { HttpClient, HttpClientRequest, HttpClientResponse } from "effect/unstable/http"
+import { OpenCode } from "../src/effect/index"
+
+const definition = Rpc.define({
+  namespace: "example",
+  methods: {
+    count: {
+      input: Schema.Struct({ count: Schema.FiniteFromString }),
+      output: Schema.FiniteFromString,
+      errors: { too_large: Schema.Struct({ limit: Schema.FiniteFromString }) },
+    },
+    echo: { input: Schema.Json, output: Schema.Json },
+    empty: { input: Schema.Undefined, output: Schema.Undefined },
+    raw: { input: { type: "string" }, output: { type: "number" } },
+  },
+  events: {
+    progress: { schema: Schema.Struct({ count: Schema.FiniteFromString }) },
+    message: { schema: Schema.Struct({ text: Schema.String }) },
+  },
+})
+
+const connected = { id: "evt_connected", type: "server.connected", data: {} }
+
+function rpcEvent(count: unknown, directory = "/project/one", namespace = "example", name = "progress") {
+  return {
+    id: "evt_progress",
+    created: 123,
+    type: `rpc.${namespace}.${name}`,
+    location: { directory },
+    metadata: { origin: "test" },
+    data: { count },
+  }
+}
+
+function eventSource() {
+  const requests: HttpClientRequest.HttpClientRequest[] = []
+  const opened = Promise.withResolvers<{
+    controller: ReadableStreamDefaultController<Uint8Array>
+    signal: AbortSignal
+  }>()
+  const cancelled = Promise.withResolvers<void>()
+  return {
+    requests,
+    opened: opened.promise,
+    cancelled: cancelled.promise,
+    async push(event: unknown) {
+      const source = await opened.promise
+      source.controller.enqueue(new TextEncoder().encode(`data: ${JSON.stringify(event)}\n\n`))
+    },
+    httpClient: HttpClient.make((request, _url, signal) => {
+      requests.push(request)
+      return Effect.succeed(
+        HttpClientResponse.fromWeb(
+          request,
+          new Response(
+            new ReadableStream<Uint8Array>({
+              start(controller) {
+                opened.resolve({ controller, signal })
+              },
+              cancel() {
+                cancelled.resolve()
+              },
+            }),
+            { headers: { "content-type": "text/event-stream" } },
+          ),
+        ),
+      )
+    }),
+  }
+}
+
+test("Effect RPC calls retain encoded inputs, decode outputs, and preserve raw native RPC calls", async () => {
+  const requests: Array<{ url: string; body: unknown }> = []
+  const httpClient = HttpClient.make((request) => {
+    const body = request.body._tag === "Uint8Array" ? JSON.parse(new TextDecoder().decode(request.body.body)) : {}
+    requests.push({ url: request.url, body })
+    return Effect.succeed(
+      HttpClientResponse.fromWeb(
+        request,
+        Response.json({
+          output: request.url.endsWith("/count") ? "42" : request.url.endsWith("/raw") ? 7 : body.input,
+        }),
+      ),
+    )
+  })
+  const result = await Effect.gen(function* () {
+    const client = yield* OpenCode.make({ baseUrl: new URL("http://localhost:3000") })
+    const rpc = client.rpc(definition)
+    const count = yield* rpc.count({ count: "2" })
+    const primitives = yield* Effect.forEach([null, false, 0, "hello", [1, "two"]], (value) => rpc.echo(value))
+    const empty = yield* rpc.empty()
+    const raw = yield* rpc.raw("input")
+    const native = yield* client.rpc.call({ namespace: "example", method: "count", input: null })
+    expect(Object.keys(rpc.events)).toEqual(["subscribe"])
+    return { count, primitives, empty, raw, native }
+  }).pipe(Effect.provideService(HttpClient.HttpClient, httpClient), Effect.runPromise)
+
+  expect(result).toEqual({
+    count: 42,
+    primitives: [null, false, 0, "hello", [1, "two"]],
+    empty: undefined,
+    raw: 7,
+    native: { output: "42" },
+  })
+  expect(requests[0]).toEqual({ url: "http://localhost:3000/api/rpc/example/count", body: { input: { count: "2" } } })
+  expect(requests.find((request) => request.url.endsWith("/empty"))?.body).toEqual({})
+})
+
+test("Effect RPC trusts server-side Standard Schema transforms for outputs and events", async () => {
+  const validations: unknown[] = []
+  const standard = {
+    "~standard": {
+      version: 1 as const,
+      vendor: "fixture",
+      validate(value: unknown) {
+        validations.push(value)
+        return { value: String(value) + " transformed" }
+      },
+    },
+  }
+  const service = Rpc.define({
+    namespace: "standard",
+    methods: { transform: { input: standard, output: standard } },
+    events: {
+      transformed: {
+        schema: {
+          "~standard": {
+            version: 1 as const,
+            vendor: "fixture",
+            validate(value: unknown) {
+              validations.push(value)
+              return { value: { text: String(value) + " transformed" } }
+            },
+          },
+        },
+      },
+    },
+  })
+  const httpClient = HttpClient.make((request) =>
+    Effect.succeed(
+      HttpClientResponse.fromWeb(
+        request,
+        request.url.endsWith("/api/event")
+          ? new Response(
+              `data: ${JSON.stringify({ ...rpcEvent(1), type: "rpc.standard.transformed", data: { text: "done" } })}\n\n`,
+              { headers: { "content-type": "text/event-stream" } },
+            )
+          : Response.json({ output: "done" }),
+      ),
+    ),
+  )
+  const result = await Effect.gen(function* () {
+    const client = yield* OpenCode.make({ baseUrl: "http://localhost:3000" })
+    const rpc = client.rpc(service)
+    return {
+      output: yield* rpc.transform("input"),
+      events: yield* Stream.runCollect(rpc.events.subscribe("transformed")),
+    }
+  }).pipe(Effect.provideService(HttpClient.HttpClient, httpClient), Effect.runPromise)
+
+  expect(result.output).toBe("done")
+  expect(result.events[0].data).toEqual({ text: "done" })
+  expect(validations).toEqual([])
+})
+
+test("Effect RPC validates decoded outputs in the failure channel", async () => {
+  const requests: string[] = []
+  const httpClient = HttpClient.make((request) => {
+    requests.push(request.url)
+    return Effect.succeed(HttpClientResponse.fromWeb(request, Response.json({ output: "not a number" })))
+  })
+  const error = await Effect.gen(function* () {
+    const client = yield* OpenCode.make({ baseUrl: "http://localhost:3000" })
+    return yield* Effect.flip(client.rpc(definition).count({ count: "1" }))
+  }).pipe(Effect.provideService(HttpClient.HttpClient, httpClient), Effect.runPromise)
+
+  expect(Schema.isSchemaError(error)).toBe(true)
+  expect(requests).toEqual(["http://localhost:3000/api/rpc/example/count"])
+})
+
+test("Effect RPC decodes declared errors and removes the generic transport wrapper", async () => {
+  const httpClient = HttpClient.make((request) =>
+    Effect.succeed(
+      HttpClientResponse.fromWeb(
+        request,
+        Response.json(
+          { _tag: "RpcError", type: "too_large", message: "Too large", data: { limit: "3" } },
+          { status: 400 },
+        ),
+      ),
+    ),
+  )
+  const error = await Effect.gen(function* () {
+    const client = yield* OpenCode.make({ baseUrl: "http://localhost:3000" })
+    return yield* client.rpc(definition).count({ count: "4" }).pipe(Effect.flip)
+  }).pipe(Effect.provideService(HttpClient.HttpClient, httpClient), Effect.runPromise)
+
+  expect(error).toEqual({ type: "too_large", message: "Too large", data: { limit: 3 } })
+})
+
+test("Effect RPC removes the internal transport wrapper", async () => {
+  const httpClient = HttpClient.make((request) =>
+    Effect.succeed(
+      HttpClientResponse.fromWeb(
+        request,
+        Response.json(
+          { _tag: "RpcInternalError", type: "rpc.internal", message: "Failed" },
+          { status: 500 },
+        ),
+      ),
+    ),
+  )
+  const error = await Effect.gen(function* () {
+    const client = yield* OpenCode.make({ baseUrl: "http://localhost:3000" })
+    return yield* client.rpc(definition).count({ count: "4" }).pipe(Effect.flip)
+  }).pipe(Effect.provideService(HttpClient.HttpClient, httpClient), Effect.runPromise)
+
+  expect(error).toEqual({ type: "rpc.internal", message: "Failed" })
+})
+
+test("Effect RPC isolates per-call location and headers while preserving configured defaults and native behavior", async () => {
+  const requests: Array<{ url: URL; headers: HttpClientRequest.HttpClientRequest["headers"] }> = []
+  const release = Promise.withResolvers<void>()
+  const started = Promise.withResolvers<void>()
+  const httpClient = HttpClient.make((request, url) => {
+    requests.push({ url, headers: request.headers })
+    if (requests.length === 1) started.resolve()
+    return Effect.promise(() => release.promise).pipe(
+      Effect.as(
+        HttpClientResponse.fromWeb(
+          request,
+          url.pathname.endsWith("/health")
+            ? Response.json({ healthy: true, version: "test", pid: 1 })
+            : Response.json({ output: "3" }),
+        ),
+      ),
+    )
+  }).pipe(HttpClient.mapRequest(HttpClientRequest.setHeaders({ authorization: "Bearer base", "x-default": "base" })))
+  const client = await Effect.runPromise(
+    OpenCode.make({ baseUrl: "http://localhost:3000" }).pipe(Effect.provideService(HttpClient.HttpClient, httpClient)),
+  )
+  const rpc = client.rpc(definition)
+  const first = Effect.runPromise(
+    rpc.count(
+      { count: "1" },
+      { location: { directory: "/project/one", workspace: "one" }, headers: { "x-call": "one" } },
+    ),
+  )
+  await started.promise
+  const second = Effect.runPromise(
+    rpc.count(
+      { count: "2" },
+      { location: { directory: "/project/two" }, headers: new Headers({ "x-call": "two", "x-default": "override" }) },
+    ),
+  )
+  const native = Effect.runPromise(client.health.get())
+  release.resolve()
+  expect(await Promise.all([first, second])).toEqual([3, 3])
+  expect(await native).toEqual({ healthy: true, version: "test", pid: 1 })
+  expect(requests.map((request) => request.headers.authorization)).toEqual([
+    "Bearer base",
+    "Bearer base",
+    "Bearer base",
+  ])
+  expect(requests.map((request) => request.headers["x-call"])).toEqual(["one", "two", undefined])
+  expect(requests.map((request) => request.headers["x-default"])).toEqual(["base", "override", "base"])
+  expect(requests.map((request) => request.url.searchParams.get("location[directory]"))).toEqual([
+    "/project/one",
+    "/project/two",
+    null,
+  ])
+  expect(requests.map((request) => request.url.searchParams.get("location[workspace]"))).toEqual(["one", null, null])
+})
+
+test("RPC signals and consumer interruption abort only their own HTTP calls", async () => {
+  const started: Array<ReturnType<typeof Promise.withResolvers<AbortSignal>>> = [
+    Promise.withResolvers<AbortSignal>(),
+    Promise.withResolvers<AbortSignal>(),
+  ]
+  const signals: AbortSignal[] = []
+  const finalized: number[] = []
+  const httpClient = HttpClient.make((_request, _url, signal) => {
+    const index = signals.length
+    signals.push(signal)
+    started[index].resolve(signal)
+    return Effect.never.pipe(Effect.ensuring(Effect.sync(() => finalized.push(index))))
+  })
+  const client = await Effect.runPromise(
+    OpenCode.make({ baseUrl: "http://localhost:3000" }).pipe(Effect.provideService(HttpClient.HttpClient, httpClient)),
+  )
+  const rpc = client.rpc(definition)
+  const abort = new AbortController()
+  const first = Effect.runFork(rpc.count({ count: "1" }, { signal: abort.signal }))
+  const second = Effect.runFork(rpc.count({ count: "2" }))
+  await Promise.all(started.map((entry) => entry.promise))
+  abort.abort()
+  const exit = await Effect.runPromise(Fiber.await(first))
+  expect(Exit.isFailure(exit) && Cause.hasInterruptsOnly(exit.cause)).toBe(true)
+  expect(signals.map((signal) => signal.aborted)).toEqual([true, false])
+  expect(finalized).toEqual([0])
+  await Effect.runPromise(Fiber.interrupt(second))
+  expect(signals[1].aborted).toBe(true)
+  expect(finalized).toEqual([0, 1])
+
+  const preAborted = await Effect.runPromiseExit(rpc.count({ count: "3" }, { signal: abort.signal }))
+  expect(Exit.isFailure(preAborted) && Cause.hasInterruptsOnly(preAborted.cause)).toBe(true)
+  expect(signals).toHaveLength(2)
+})
+
+test("native and RPC Effect streams share one lazy source, cache connected, and filter across all locations", async () => {
+  const source = eventSource()
+  const client = await Effect.runPromise(
+    OpenCode.make({ baseUrl: "http://localhost:3000" }).pipe(
+      Effect.provideService(HttpClient.HttpClient, source.httpClient),
+    ),
+  )
+  const rpc = client.rpc(definition)
+  const native = Stream.toAsyncIterable(client.event.subscribe())[Symbol.asyncIterator]()
+  const progress = Stream.toAsyncIterable(rpc.events.subscribe("progress"))[Symbol.asyncIterator]()
+  expect(source.requests).toHaveLength(0)
+  const marker = native.next()
+  await source.push(connected)
+  expect((await marker).value).toEqual(connected)
+
+  const first = progress.next()
+  const late = Stream.toAsyncIterable(client.event.subscribe())[Symbol.asyncIterator]()
+  expect((await late.next()).value).toEqual(connected)
+  await native.return?.()
+  await late.return?.()
+  await source.push(rpcEvent("ignored", "/project/one", "other"))
+  await source.push(rpcEvent("ignored", "/project/one", "example", "message"))
+  await source.push(rpcEvent("1"))
+  expect((await first).value).toEqual({
+    id: "evt_progress",
+    created: 123,
+    type: "rpc.example.progress",
+    metadata: { origin: "test" },
+    data: { count: 1 },
+    location: { directory: "/project/one" },
+  })
+  const second = progress.next()
+  await source.push(rpcEvent("2", "/project/two"))
+  expect((await second).value).toEqual(
+    expect.objectContaining({ data: { count: 2 }, location: { directory: "/project/two" } }),
+  )
+  expect(source.requests).toHaveLength(1)
+
+  expect((await source.opened).signal.aborted).toBe(false)
+  const third = progress.next()
+  await source.push(rpcEvent("3"))
+  expect((await third).value.data).toEqual({ count: 3 })
+  const pending = progress.next()
+  await progress.return?.()
+  expect((await pending).done).toBe(true)
+  await source.cancelled
+  expect((await source.opened).signal.aborted).toBe(true)
+})
+
+test("interrupting a native Effect stream leaves an active RPC consumer running", async () => {
+  const source = eventSource()
+  const client = await Effect.runPromise(
+    OpenCode.make({ baseUrl: "http://localhost:3000" }).pipe(
+      Effect.provideService(HttpClient.HttpClient, source.httpClient),
+    ),
+  )
+  const native = Effect.runFork(Stream.runCollect(client.event.subscribe()))
+  const progress = Stream.toAsyncIterable(client.rpc(definition).events.subscribe("progress"))[Symbol.asyncIterator]()
+  const first = progress.next()
+  await source.push(rpcEvent("1"))
+  expect((await first).value.data).toEqual({ count: 1 })
+  await Effect.runPromise(Fiber.interrupt(native))
+  expect((await source.opened).signal.aborted).toBe(false)
+  const second = progress.next()
+  await source.push(rpcEvent("2"))
+  expect((await second).value.data).toEqual({ count: 2 })
+  await progress.return?.()
+  await source.cancelled
+})
+
+test("shared Effect streams preserve EOF without reconnecting", async () => {
+  const source = eventSource()
+  const client = await Effect.runPromise(
+    OpenCode.make({ baseUrl: "http://localhost:3000" }).pipe(
+      Effect.provideService(HttpClient.HttpClient, source.httpClient),
+    ),
+  )
+  const native = Effect.runPromise(Stream.runCollect(client.event.subscribe()))
+  const progress = Effect.runPromise(Stream.runCollect(client.rpc(definition).events.subscribe("progress")))
+  await source.push(connected)
+  await source.push(rpcEvent("1"))
+  const connection = await source.opened
+  connection.controller.close()
+  expect((await native).map((event) => event.type)).toEqual(["server.connected", "rpc.example.progress"])
+  expect((await progress).map((event) => event.data)).toEqual([{ count: 1 }])
+  expect(source.requests).toHaveLength(1)
+})
+
+test("native protocol failures reach both native and RPC streams as ClientError", async () => {
+  const source = eventSource()
+  const client = await Effect.runPromise(
+    OpenCode.make({ baseUrl: "http://localhost:3000" }).pipe(
+      Effect.provideService(HttpClient.HttpClient, source.httpClient),
+    ),
+  )
+  const native = Effect.runPromise(Effect.flip(Stream.runCollect(client.event.subscribe())))
+  const progress = Effect.runPromise(
+    Effect.flip(Stream.runCollect(client.rpc(definition).events.subscribe("progress"))),
+  )
+  await source.push({ type: "server.connected" })
+  expect((await native)._tag).toBe("ClientError")
+  expect(await progress).toBe(await native)
+  expect(source.requests).toHaveLength(1)
+})
+
+test("HTTP source failures reach every Effect consumer", async () => {
+  const source = eventSource()
+  const client = await Effect.runPromise(
+    OpenCode.make({ baseUrl: "http://localhost:3000" }).pipe(
+      Effect.provideService(HttpClient.HttpClient, source.httpClient),
+    ),
+  )
+  const native = Effect.runPromise(Effect.flip(Stream.runCollect(client.event.subscribe())))
+  const progress = Effect.runPromise(
+    Effect.flip(Stream.runCollect(client.rpc(definition).events.subscribe("progress"))),
+  )
+  await source.push(connected)
+  const connection = await source.opened
+  connection.controller.error(new Error("connection lost"))
+  expect((await native)._tag).toBe("ClientError")
+  expect(await progress).toBe(await native)
+  expect(source.requests).toHaveLength(1)
+})
+
+test("RPC payload decoding fails only the matching consumer, not the native event stream", async () => {
+  const source = eventSource()
+  const client = await Effect.runPromise(
+    OpenCode.make({ baseUrl: "http://localhost:3000" }).pipe(
+      Effect.provideService(HttpClient.HttpClient, source.httpClient),
+    ),
+  )
+  const native = Stream.toAsyncIterable(client.event.subscribe())[Symbol.asyncIterator]()
+  const raw = native.next()
+  const progress = Effect.runPromise(
+    Effect.flip(Stream.runCollect(client.rpc(definition).events.subscribe("progress"))),
+  )
+  await source.push(rpcEvent("not a number"))
+  expect((await raw).value.type).toBe("rpc.example.progress")
+  expect(Schema.isSchemaError(await progress)).toBe(true)
+  expect((await source.opened).signal.aborted).toBe(false)
+  const next = native.next()
+  await source.push(connected)
+  expect((await next).value.type).toBe("server.connected")
+  await native.return?.()
+  await source.cancelled
+})
+
+test("shared event source runs with the Effect context captured by make", async () => {
+  const Token = Context.Reference("test/rpc-effect/token", { defaultValue: () => "missing" })
+  const httpClient = HttpClient.make((request) =>
+    Effect.gen(function* () {
+      const token = yield* Token
+      expect(token).toBe("captured")
+      return HttpClientResponse.fromWeb(
+        request,
+        new Response(`data: ${JSON.stringify(connected)}\n\n`, { headers: { "content-type": "text/event-stream" } }),
+      )
+    }),
+  )
+  const client = await Effect.runPromise(
+    OpenCode.make({ baseUrl: "http://localhost:3000" }).pipe(
+      Effect.provideService(HttpClient.HttpClient, httpClient),
+      Effect.provideService(Token, "captured"),
+    ),
+  )
+  expect((await Effect.runPromise(Stream.runCollect(client.event.subscribe())))[0]).toEqual(connected)
+})
+
+test("Effect RPC rejects inherited event names without opening the source", async () => {
+  const requests: string[] = []
+  const httpClient = HttpClient.make((request) => {
+    requests.push(request.url)
+    return Effect.die(new Error("Unexpected request"))
+  })
+  const error = await Effect.gen(function* () {
+    const client = yield* OpenCode.make({ baseUrl: "http://localhost:3000" })
+    const broad: Rpc.Definition = definition
+    return yield* client.rpc(broad).events.subscribe("toString").pipe(Stream.runDrain, Effect.flip)
+  }).pipe(Effect.provideService(HttpClient.HttpClient, httpClient), Effect.runPromise)
+
+  expect(error).toEqual(new Error("Unknown RPC event: rpc.example.toString"))
+  expect(requests).toEqual([])
+})

packages/client/test/rpc-promise.test.ts

@@ -0,0 +1,361 @@
+import { afterEach, expect, test } from "bun:test"
+import type { StandardSchemaV1 } from "@standard-schema/spec"
+import { Rpc } from "@opencode-ai/schema/rpc"
+import { z } from "zod"
+import { OpenCode } from "../src/promise/index"
+
+const cleanup = new Set<() => void>()
+afterEach(() => {
+  cleanup.forEach((close) => close())
+  cleanup.clear()
+})
+
+const Echo = Rpc.define({
+  namespace: "acme/jobs",
+  methods: {
+    echo: {
+      input: z.string(),
+      output: z.string(),
+      errors: { rejected: z.object({ reason: z.string() }) },
+    },
+    raw: { input: z.unknown(), output: z.unknown() },
+    ping: { input: z.undefined(), output: z.undefined() },
+  },
+  events: {
+    updated: { schema: z.object({ count: z.number() }) },
+  },
+})
+const connected = { id: "evt_connected", created: 0, type: "server.connected", data: {} }
+const rpcEvent = (data: unknown, directory = "/first", namespace = Echo.namespace, name = "updated") => ({
+  id: "evt_rpc",
+  created: 10,
+  type: `rpc.${namespace}.${name}`,
+  location: { directory },
+  metadata: { source: "test" },
+  data,
+})
+function http(fetch: (request: Request) => Response | Promise<Response>) {
+  const server = Bun.serve({ hostname: "127.0.0.1", port: 0, fetch })
+  cleanup.add(() => server.stop(true))
+  return OpenCode.make({ baseUrl: server.url.href, headers: { authorization: "Bearer default", "x-base": "base" } })
+}
+
+function events() {
+  const requests: Request[] = []
+  const opened = Promise.withResolvers<ReadableStreamDefaultController<Uint8Array>>()
+  const cancelled = Promise.withResolvers<void>()
+  const encoder = new TextEncoder()
+  let stopped = false
+  const client = OpenCode.make({
+    baseUrl: "http://localhost:3000",
+    headers: { authorization: "Bearer events" },
+    fetch: async (input, init) => {
+      const request = new Request(input, init)
+      requests.push(request)
+      const stream = new ReadableStream<Uint8Array>({
+        start(controller) {
+          const abort = () => {
+            if (stopped) return
+            stopped = true
+            controller.error(request.signal.reason)
+            cancelled.resolve()
+          }
+          request.signal.addEventListener("abort", abort, { once: true })
+          cleanup.add(abort)
+          opened.resolve(controller)
+          controller.enqueue(encoder.encode(`data: ${JSON.stringify(connected)}\n\n`))
+        },
+        cancel() {
+          stopped = true
+          cancelled.resolve()
+        },
+      })
+      return new Response(stream, { headers: { "content-type": "text/event-stream" } })
+    },
+  })
+  return {
+    client,
+    requests,
+    cancelled: cancelled.promise,
+    async send(value: unknown) {
+      return (await opened.promise).enqueue(encoder.encode(`data: ${JSON.stringify(value)}\n\n`))
+    },
+    async end() {
+      stopped = true
+      return (await opened.promise).close()
+    },
+    async fail(error: Error) {
+      stopped = true
+      return (await opened.promise).error(error)
+    },
+  }
+}
+
+test("rpc is callable, retains raw call, and routes method location, headers, and JSON body", async () => {
+  const requests: Array<{ url: string; method: string; headers: Headers; body: unknown }> = []
+  const client = http(async (request) => {
+    const body = await request.json()
+    requests.push({ url: request.url, method: request.method, headers: request.headers, body })
+    return Response.json({ output: body.input })
+  })
+  expect(typeof client.rpc).toBe("function")
+  expect(typeof client.rpc.call).toBe("function")
+  expect(
+    await client.rpc(Echo).echo("hello", {
+      location: { directory: "/project with spaces", workspace: "wrk_test" },
+      headers: { authorization: "Bearer override", "x-call": "call" },
+    }),
+  ).toBe("hello")
+  const url = new URL(requests[0].url)
+  expect(url.pathname).toBe("/api/rpc/acme%2Fjobs/echo")
+  expect(url.searchParams.get("location[directory]")).toBe("/project with spaces")
+  expect(url.searchParams.get("location[workspace]")).toBe("wrk_test")
+  expect(requests[0].body).toEqual({ input: "hello" })
+  expect(requests[0].method).toBe("POST")
+  expect(requests[0].headers.get("authorization")).toBe("Bearer override")
+  expect(requests[0].headers.get("x-base")).toBe("base")
+  expect(requests[0].headers.get("x-call")).toBe("call")
+  expect(await client.rpc.call({ namespace: Echo.namespace, method: "echo", input: "raw" })).toEqual({ output: "raw" })
+  expect(new URL(requests[1].url).search).toBe("")
+  expect(requests[1].headers.get("authorization")).toBe("Bearer default")
+})
+
+test("no-input RPC methods and absent output use empty wrappers", async () => {
+  const client = http(async (request) => {
+    expect(await request.json()).toEqual({})
+    return Response.json({})
+  })
+  expect(await client.rpc(Echo).ping()).toBeUndefined()
+  expect(await client.rpc(Echo).ping(undefined, { location: { directory: "/project" } })).toBeUndefined()
+})
+
+test("RPC Standard Schema results are already parsed and are not transformed again", async () => {
+  const calls = { input: 0, output: 0 }
+  const input: StandardSchemaV1<string, number> = {
+    "~standard": {
+      version: 1,
+      vendor: "test",
+      validate: (value) => {
+        calls.input++
+        return { value: Number(value) }
+      },
+    },
+  }
+  const output: StandardSchemaV1<number, string> = {
+    "~standard": {
+      version: 1,
+      vendor: "test",
+      validate: (value) => {
+        calls.output++
+        return { value: String(value) }
+      },
+    },
+  }
+  const eventOutput: StandardSchemaV1<{ count: number }, { text: string }> = {
+    "~standard": {
+      version: 1,
+      vendor: "test",
+      validate: (value) => {
+        if (typeof value !== "object" || value === null || !("count" in value) || typeof value.count !== "number")
+          return { issues: [{ message: "Expected count" }] }
+        return { value: { text: String(value.count) } }
+      },
+    },
+  }
+  const definition = Rpc.define({
+    namespace: "standard",
+    methods: { count: { input, output } },
+    events: { counted: { schema: eventOutput } },
+  })
+  const client = http(async (request) => {
+    expect(await request.json()).toEqual({ input: "41" })
+    return Response.json({ output: "42" })
+  })
+  expect(await client.rpc(definition).count("41")).toBe("42")
+  const source = events()
+  const iterator = source.client.rpc(definition).events.subscribe("counted")[Symbol.asyncIterator]()
+  const next = iterator.next()
+  await source.send(rpcEvent({ text: "42" }, "/project", definition.namespace, "counted"))
+  expect((await next).value?.data).toEqual({ text: "42" })
+  await iterator.return?.()
+  expect(calls).toEqual({ input: 0, output: 0 })
+})
+
+test("RPC method signals cancel an in-flight HTTP request", async () => {
+  const received = Promise.withResolvers<void>()
+  const response = Promise.withResolvers<Response>()
+  const client = http(() => {
+    received.resolve()
+    return response.promise
+  })
+  const controller = new AbortController()
+  const result = client
+    .rpc(Echo)
+    .echo("hello", { signal: controller.signal })
+    .catch((error: unknown) => error)
+  await received.promise
+  controller.abort()
+  expect(await result).toMatchObject({ name: "ClientError", reason: "Transport" })
+  response.resolve(Response.json({ output: "late" }))
+})
+
+test("RPC pre-aborted methods do not issue HTTP requests", async () => {
+  let requests = 0
+  const client = http(() => {
+    requests++
+    return Response.json({ output: "hello" })
+  })
+  await expect(client.rpc(Echo).echo("hello", { signal: AbortSignal.abort() })).rejects.toBeDefined()
+  expect(requests).toBe(0)
+})
+
+test("RPC declared HTTP failures propagate", async () => {
+  await expect(
+    http(() => Response.json({ _tag: "UnauthorizedError", message: "Denied" }, { status: 401 }))
+      .rpc(Echo)
+      .echo("hello"),
+  ).rejects.toMatchObject({ _tag: "UnauthorizedError", message: "Denied" })
+})
+
+test("RPC method failures remove the generic transport wrapper", async () => {
+  const response = { _tag: "RpcError", type: "rejected", message: "Rejected", data: { reason: "busy" } }
+  const client = http(() => Response.json(response, { status: 400 }))
+  const error = await client.rpc(Echo).echo("hello").catch((error: unknown) => error)
+
+  expect(error).toEqual({ type: "rejected", message: "Rejected", data: { reason: "busy" } })
+  await expect(client.rpc.call({ namespace: Echo.namespace, method: "echo", input: "hello" })).rejects.toEqual(response)
+})
+
+test("RPC transport failures remove the generic transport wrapper", async () => {
+  const response = { _tag: "RpcInternalError", type: "rpc.internal", message: "Failed" }
+  await expect(http(() => Response.json(response, { status: 500 })).rpc(Echo).echo("hello")).rejects.toEqual({
+    type: "rpc.internal",
+    message: "Failed",
+  })
+})
+
+test("native events and multiple RPC clients share one lazy source across locations", async () => {
+  const source = events()
+  const native = source.client.event.subscribe()[Symbol.asyncIterator]()
+  const first = source.client.rpc(Echo).events.subscribe("updated")[Symbol.asyncIterator]()
+  const second = source.client.rpc(Echo).events.subscribe("updated")[Symbol.asyncIterator]()
+  const otherDefinition = Rpc.define({ ...Echo, namespace: "other" })
+  const other = source.client.rpc(otherDefinition).events.subscribe("updated")[Symbol.asyncIterator]()
+  expect(source.requests).toHaveLength(0)
+  const firstNext = first.next()
+  const secondNext = second.next()
+  const otherNext = other.next()
+  expect(await native.next()).toEqual({ done: false, value: connected })
+  expect(source.requests).toHaveLength(1)
+  expect(source.requests[0].headers.get("authorization")).toBe("Bearer events")
+  const late = source.client.event.subscribe()[Symbol.asyncIterator]()
+  expect(await late.next()).toEqual({ done: false, value: connected })
+  await Promise.all([native.return?.(), late.return?.()])
+  await source.send(rpcEvent({ ignored: true }, "/first", Echo.namespace, "unknown"))
+  await source.send(rpcEvent({ count: 9 }, "/other", otherDefinition.namespace))
+  expect((await otherNext).value).toMatchObject({
+    type: "rpc.other.updated",
+    location: { directory: "/other" },
+    data: { count: 9 },
+  })
+  await other.return?.()
+  await source.send(rpcEvent({ count: 42 }))
+  const expected = {
+    id: "evt_rpc",
+    created: 10,
+    type: `rpc.${Echo.namespace}.updated`,
+    location: { directory: "/first" },
+    metadata: { source: "test" },
+    data: { count: 42 },
+  }
+  expect(await firstNext).toEqual({ done: false, value: expected })
+  expect(await secondNext).toEqual({ done: false, value: expected })
+  const next = first.next()
+  await source.send(rpcEvent({ count: 43 }, "/second"))
+  expect((await next).value).toMatchObject({ location: { directory: "/second" }, data: { count: 43 } })
+  await Promise.all([first.return?.(), second.return?.()])
+  await source.cancelled
+  expect(source.requests[0].signal.aborted).toBe(true)
+  expect(source.requests).toHaveLength(1)
+})
+
+test("RPC iterator return and abort cancel only their pending subscribers", async () => {
+  const source = events()
+  const controller = new AbortController()
+  const first = source.client.rpc(Echo).events.subscribe("updated")[Symbol.asyncIterator]()
+  const secondEvents = source.client.rpc(Echo).events.subscribe("updated", { signal: controller.signal })
+  const second = secondEvents[Symbol.asyncIterator]()
+  const native = source.client.event.subscribe()[Symbol.asyncIterator]()
+  const firstNext = first.next()
+  const secondNext = second.next()
+  await native.next()
+  expect((await first.return?.())?.done).toBe(true)
+  expect((await firstNext).done).toBe(true)
+  expect(source.requests[0].signal.aborted).toBe(false)
+  controller.abort()
+  expect((await secondNext).done).toBe(true)
+  expect(source.requests[0].signal.aborted).toBe(false)
+  const nativeNext = native.next()
+  const event = rpcEvent({ count: 42 })
+  await source.send(event)
+  expect(await nativeNext).toEqual({ done: false, value: event })
+  await native.return?.()
+  await source.cancelled
+})
+
+test("RPC callback subscriptions unsubscribe independently", async () => {
+  const source = events()
+  const received = Promise.withResolvers<unknown>()
+  const native = source.client.event.subscribe()[Symbol.asyncIterator]()
+  await native.next()
+  const unsubscribe = source.client.rpc(Echo).events.on("updated", received.resolve)
+  await source.send(rpcEvent({ count: 42 }))
+  expect(await received.promise).toMatchObject({ data: { count: 42 }, type: `rpc.${Echo.namespace}.updated` })
+  unsubscribe()
+  unsubscribe()
+  expect(source.requests[0].signal.aborted).toBe(false)
+  await native.return?.()
+  await source.cancelled
+})
+
+test("RPC async callback failures stop only that listener and are not unhandled", async () => {
+  const source = events()
+  const client = source.client.rpc(Echo)
+  const started = Promise.withResolvers<void>()
+  const release = Promise.withResolvers<void>()
+  const failed: number[] = []
+  cleanup.add(release.resolve)
+  cleanup.add(
+    client.events.on("updated", async (event) => {
+      failed.push(event.data.count)
+      started.resolve()
+      await release.promise
+      throw new Error("Expected async RPC callback failure")
+    }),
+  )
+  const healthy = client.events.subscribe("updated")[Symbol.asyncIterator]()
+  const first = healthy.next()
+  await source.send(rpcEvent({ count: 1 }))
+  await started.promise
+  expect((await first).value.data.count).toBe(1)
+  const second = healthy.next()
+  await source.send(rpcEvent({ count: 2 }))
+  expect((await second).value.data.count).toBe(2)
+  expect(failed).toEqual([1])
+  release.resolve()
+  await healthy.return?.()
+  await source.cancelled
+  expect(failed).toEqual([1])
+})
+
+test("RPC checks unknown event names and pre-aborted subscriptions remain lazy", async () => {
+  const source = events()
+  const broad: Rpc.PortableDefinition = Echo
+  expect(() => source.client.rpc(broad).events.subscribe("unknown")).toThrow("Unknown RPC event")
+  expect(() => source.client.rpc(broad).events.subscribe("toString")).toThrow("Unknown RPC event")
+  expect(() => source.client.rpc(broad).events.on("unknown", () => {})).toThrow("Unknown RPC event")
+  const aborted = source.client.rpc(Echo).events.subscribe("updated", { signal: AbortSignal.abort() })
+  const iterator = aborted[Symbol.asyncIterator]()
+  expect((await iterator.next()).done).toBe(true)
+  expect(source.requests).toHaveLength(0)
+})

packages/client/test/shared-events.test.ts

@@ -0,0 +1,281 @@
+import { expect, test } from "bun:test"
+import { SharedEvents } from "../src/shared-events"
+
+type Event = { readonly type: string; readonly value?: number }
+
+function source(cleanup?: Promise<void>) {
+  const connections: {
+    signal: AbortSignal
+    push: (event: Event) => void
+    close: () => void
+    fail: (error: unknown) => void
+    closing: Promise<void>
+    closed: Promise<void>
+  }[] = []
+  const opened: ReturnType<typeof Promise.withResolvers<void>>[] = []
+
+  return {
+    connections,
+    async at(index: number) {
+      if (!connections[index]) await (opened[index] ??= Promise.withResolvers<void>()).promise
+      return connections[index]
+    },
+    connect(signal: AbortSignal): AsyncIterable<Event> {
+      let controller!: ReadableStreamDefaultController<Event>
+      let ended = false
+      const closing = Promise.withResolvers<void>()
+      const closed = Promise.withResolvers<void>()
+      const stream = new ReadableStream<Event>({
+        start(value) {
+          controller = value
+        },
+      })
+      const close = () => {
+        if (ended) return
+        ended = true
+        controller.close()
+      }
+      signal.addEventListener("abort", close, { once: true })
+      connections.push({
+        signal,
+        push: (event) => controller.enqueue(event),
+        close,
+        fail(error) {
+          ended = true
+          controller.error(error)
+        },
+        closing: closing.promise,
+        closed: closed.promise,
+      })
+      opened[connections.length - 1]?.resolve()
+
+      return (async function* () {
+        try {
+          yield* stream
+        } finally {
+          signal.removeEventListener("abort", close)
+          closing.resolve()
+          await cleanup
+          closed.resolve()
+        }
+      })()
+    },
+  }
+}
+
+test("creation, subscription, and idle iterators are lazy", async () => {
+  const events = source()
+  const shared = SharedEvents.make(events.connect)
+  const iterable = shared.subscribe()
+  const idle = iterable[Symbol.asyncIterator]()
+  expect(events.connections).toHaveLength(0)
+  expect(await idle.return!()).toEqual({ done: true, value: undefined })
+  expect(await idle.next()).toEqual({ done: true, value: undefined })
+  expect(events.connections).toHaveLength(0)
+
+  const active = iterable[Symbol.asyncIterator]()
+  const next = active.next()
+  expect(events.connections).toHaveLength(1)
+  events.connections[0].push({ type: "server.connected" })
+  expect(await next).toEqual({ done: false, value: { type: "server.connected" } })
+  await active.return!()
+  await events.connections[0].closed
+})
+
+test("pre-aborted subscribers do not open a source", async () => {
+  const events = source()
+  const controller = new AbortController()
+  const iterator = SharedEvents.make(events.connect).subscribe({ signal: controller.signal })[Symbol.asyncIterator]()
+  controller.abort()
+  expect(await iterator.next()).toEqual({ done: true, value: undefined })
+  expect(events.connections).toHaveLength(0)
+})
+
+test("multiple consumers share one source and receive live native and RPC events", async () => {
+  const events = source()
+  const shared = SharedEvents.make(events.connect)
+  const first = shared.subscribe()[Symbol.asyncIterator]()
+  const second = shared.subscribe()[Symbol.asyncIterator]()
+
+  for (const event of [{ type: "server.connected" }, { type: "session.updated" }, { type: "rpc.example.updated", value: 1 }]) {
+    const reads = [first.next(), second.next()]
+    events.connections[0].push(event)
+    expect(await Promise.all(reads)).toEqual([
+      { done: false, value: event },
+      { done: false, value: event },
+    ])
+  }
+  expect(events.connections).toHaveLength(1)
+  await first.return!()
+  expect(events.connections[0].signal.aborted).toBe(false)
+  const next = second.next()
+  events.connections[0].push({ type: "rpc.example.updated", value: 2 })
+  expect((await next).value).toEqual({ type: "rpc.example.updated", value: 2 })
+  await second.return!()
+  await events.connections[0].closed
+})
+
+test("late consumers receive the latest connection marker but no business event replay", async () => {
+  const events = source()
+  const shared = SharedEvents.make(events.connect)
+  const first = shared.subscribe()[Symbol.asyncIterator]()
+  const idle = shared.subscribe()[Symbol.asyncIterator]()
+  for (const event of [
+    { type: "server.connected", value: 1 },
+    { type: "server.connected", value: 2 },
+    { type: "rpc.example.updated", value: 3 },
+  ]) {
+    const next = first.next()
+    events.connections[0].push(event)
+    await next
+  }
+
+  expect(await idle.next()).toEqual({ done: false, value: { type: "server.connected", value: 2 } })
+  const next = idle.next()
+  events.connections[0].push({ type: "rpc.example.updated", value: 4 })
+  expect(await next).toEqual({ done: false, value: { type: "rpc.example.updated", value: 4 } })
+  expect(events.connections).toHaveLength(1)
+  await first.return!()
+  await idle.return!()
+  await events.connections[0].closed
+})
+
+test("abort removes only its subscriber; last return closes the native source and resolves pending reads", async () => {
+  const events = source()
+  const shared = SharedEvents.make(events.connect)
+  const controller = new AbortController()
+  const first = shared.subscribe({ signal: controller.signal })[Symbol.asyncIterator]()
+  const second = shared.subscribe()[Symbol.asyncIterator]()
+  const firstRead = first.next()
+  const secondReads = [second.next(), second.next()]
+  controller.abort()
+  expect(await firstRead).toEqual({ done: true, value: undefined })
+  expect(await first.next()).toEqual({ done: true, value: undefined })
+  expect(events.connections[0].signal.aborted).toBe(false)
+
+  await second.return!()
+  expect(await Promise.all(secondReads)).toEqual([
+    { done: true, value: undefined },
+    { done: true, value: undefined },
+  ])
+  expect(events.connections[0].signal.aborted).toBe(true)
+  await events.connections[0].closed
+  expect(await second.next()).toEqual({ done: true, value: undefined })
+})
+
+test("breaking a native for-await loop closes the last source", async () => {
+  const events = source()
+  const shared = SharedEvents.make(events.connect)
+  const consumed = (async () => {
+    for await (const event of shared.subscribe()) {
+      expect(event.type).toBe("server.connected")
+      break
+    }
+  })()
+  events.connections[0].push({ type: "server.connected" })
+  await consumed
+  expect(events.connections[0].signal.aborted).toBe(true)
+  await events.connections[0].closed
+})
+
+test("rapid resubscription opens a replacement while old cleanup finishes", async () => {
+  const cleanup = Promise.withResolvers<void>()
+  const events = source(cleanup.promise)
+  const shared = SharedEvents.make(events.connect)
+  const first = shared.subscribe()[Symbol.asyncIterator]()
+  const firstRead = first.next()
+  events.connections[0].push({ type: "server.connected", value: 1 })
+  await firstRead
+  await first.return!()
+  await events.connections[0].closing
+
+  const second = shared.subscribe()[Symbol.asyncIterator]()
+  const third = shared.subscribe()[Symbol.asyncIterator]()
+  const secondRead = second.next()
+  const thirdRead = third.next()
+  const controller = new AbortController()
+  const cancelled = shared.subscribe({ signal: controller.signal })[Symbol.asyncIterator]()
+  const cancelledRead = cancelled.next()
+  controller.abort()
+  expect(await cancelledRead).toEqual({ done: true, value: undefined })
+  expect(events.connections).toHaveLength(2)
+
+  const replacement = await events.at(1)
+  replacement.push({ type: "server.connected", value: 2 })
+  expect(await Promise.all([secondRead, thirdRead])).toEqual([
+    { done: false, value: { type: "server.connected", value: 2 } },
+    { done: false, value: { type: "server.connected", value: 2 } },
+  ])
+  cleanup.resolve()
+  await events.connections[0].closed
+  await second.return!()
+  await third.return!()
+  await replacement.closed
+})
+
+test("source EOF finishes all consumers and permits a fresh subscription without retry", async () => {
+  const events = source()
+  const shared = SharedEvents.make(events.connect)
+  const first = shared.subscribe()[Symbol.asyncIterator]()
+  const second = shared.subscribe()[Symbol.asyncIterator]()
+  const reads = [first.next(), second.next()]
+  events.connections[0].push({ type: "server.connected", value: 1 })
+  await Promise.all(reads)
+  const nextReads = [first.next(), second.next()]
+  events.connections[0].push({ type: "rpc.example.updated", value: 2 })
+  expect(await Promise.all(nextReads)).toEqual([
+    { done: false, value: { type: "rpc.example.updated", value: 2 } },
+    { done: false, value: { type: "rpc.example.updated", value: 2 } },
+  ])
+  events.connections[0].close()
+  await events.connections[0].closed
+  expect(await first.next()).toEqual({ done: true, value: undefined })
+  expect(await second.next()).toEqual({ done: true, value: undefined })
+  expect(events.connections).toHaveLength(1)
+
+  const fresh = shared.subscribe()[Symbol.asyncIterator]()
+  const next = fresh.next()
+  const replacement = await events.at(1)
+  replacement.push({ type: "server.connected", value: 3 })
+  expect(await next).toEqual({ done: false, value: { type: "server.connected", value: 3 } })
+  await fresh.return!()
+  await replacement.closed
+})
+
+test("source failures preserve error identity for every consumer and permit a new subscription", async () => {
+  const events = source()
+  const shared = SharedEvents.make(events.connect)
+  const first = shared.subscribe()[Symbol.asyncIterator]()
+  const second = shared.subscribe()[Symbol.asyncIterator]()
+  const failure = { reason: "actual source failure" }
+  const reads = Promise.allSettled([first.next(), second.next()])
+  events.connections[0].fail(failure)
+  expect(await reads).toEqual([
+    { status: "rejected", reason: failure },
+    { status: "rejected", reason: failure },
+  ])
+  await expect(first.next()).rejects.toBe(failure)
+  expect(events.connections).toHaveLength(1)
+
+  const fresh = shared.subscribe()[Symbol.asyncIterator]()
+  const next = fresh.next()
+  const replacement = await events.at(1)
+  replacement.push({ type: "server.connected" })
+  expect(await next).toEqual({ done: false, value: { type: "server.connected" } })
+  await fresh.return!()
+  await replacement.closed
+})
+
+test("synchronous source creation failures reject subscribers without automatic retry", async () => {
+  const failure = new Error("connect failed")
+  const attempts: AbortSignal[] = []
+  const shared = SharedEvents.make<Event>((signal) => {
+    attempts.push(signal)
+    throw failure
+  })
+  await expect(shared.subscribe()[Symbol.asyncIterator]().next()).rejects.toBe(failure)
+  expect(attempts).toHaveLength(1)
+  expect(attempts[0].aborted).toBe(true)
+  await expect(shared.subscribe()[Symbol.asyncIterator]().next()).rejects.toBe(failure)
+  expect(attempts).toHaveLength(2)
+})