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packages/app/e2e/performance/AGENTS.md

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+- Prioritize stability, then simplicity, then measurement overhead.
+- Use Playwright for scenario control, isolation, and completion checks.
+- Use Chrome Performance traces for generic browser profiling.
+- Use Electron `contentTracing` for packaged multi-process profiling.
+- Keep custom probes only for product-specific measurements.
+- Do not duplicate measurements across the harness, probes, and traces.
+- Run benchmarks serially to avoid cross-test contention.
+- Run benchmarks against production builds.
+- Keep detailed profiling opt-in when it changes workload behavior.
+- Preserve raw diagnostic data or use lossless representations.
+- Do not enforce machine-dependent performance thresholds.
+- Assert scenario completion and metric collection only.
+- Keep normal test discovery free of manual benchmarks.

packages/app/e2e/performance/README.md

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+# Manual app performance suite
+
+The app's high-volume performance diagnostics live under `packages/app/e2e/performance` and are excluded from normal local and CI Playwright discovery. The benchmark config builds the app and serves the production bundle before running scenarios serially.
+
+Run the suite explicitly from `packages/app`:
+
+```sh
+bun run test:bench
+```
+
+PowerShell:
+
+```powershell
+$env:PLAYWRIGHT_WORKERS = "1"
+bun run test:bench
+```
+
+The suite contains:
+
+- cold and hot session-tab timing
+- home-session click timing split between content and titlebar-tab paint
+- single-session tab close timing through stable home restoration
+- cached session repaint and mutation tracing
+- streaming timeline throughput, RAF-gap, long-task, geometry, and remount diagnostics
+
+All benchmarks import the shared `benchmark` fixture. Pages created through Playwright's `page` fixture automatically capture main-frame navigation history and emit a Chrome trace when `OPENCODE_PERFORMANCE_TRACE_DIR` is set. Benchmarks that need isolated browser contexts use `withBenchmarkPage`, which owns the context and the same diagnostics lifecycle.
+
+New benchmarks should look like normal Playwright tests:
+
+```ts
+import { benchmark, expect } from "../benchmark"
+
+benchmark("measures one interaction", async ({ page, report }) => {
+  // Only scenario-specific setup and interaction belong here.
+  report({ durationMs: 42 })
+})
+```
+
+The fixture requires every benchmark to call `report()`, automatically names and closes traces, captures navigation history, attaches that history when a test fails, and emits metrics as a consistent `BENCHMARK` JSON line.
+
+```text
+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.
+
+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).
+
+These Playwright benchmarks profile the shared app renderer in Chromium. A future packaged Electron benchmark that needs main-process and multi-process attribution should use Electron's official [`contentTracing`](https://www.electronjs.org/docs/latest/api/content-tracing/) API rather than extending this renderer harness with bespoke process instrumentation.
+
+CPU and high-volume visual profiling are disabled by default. Set `TIMELINE_CPU_PROFILE=1` to enable both, or additionally set `TIMELINE_VISUAL_PROFILE=0` for CPU-only profiling.
+
+The streaming scenario's 30x CPU throttle is a deterministic stress profile, not a simulated end-user device.
+
+Benchmarks do not assert machine-dependent performance budgets. Streaming processes 160 deltas by default and reports renderer-observed completion time, throughput, RAF callback-gap distributions, frame-budget equivalents, and long tasks through final geometry settlement. Delta count and delivery batch are included in result context when overridden. These are main-thread callback diagnostics, not compositor presentation or dropped-frame measurements. Visual-only and geometry metrics are `null` when their probes are disabled. Tab metrics describe sampled DOM observations. Assertions verify scenario and metric collection completion. Repeated repaint states are run-length grouped, but every original observation timestamp is retained alongside raw mutation batches and layout shifts.
+
+Committed smoke and regression tests continue to own correctness coverage for pagination, tab paint, context resize, collapse state, and composer spacing.
+
+## Chrome traces
+
+Set `OPENCODE_PERFORMANCE_TRACE_DIR` to emit a standard Chrome DevTools trace for every benchmark page automatically:
+
+```sh
+OPENCODE_PERFORMANCE_TRACE_DIR=/tmp/opencode-performance-traces \
+bunx playwright test --config e2e/performance/playwright.config.ts \
+  timeline/session-tab-switch-benchmark.spec.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.
+
+```sh
+bunx devtools-tracing stats <trace-path-from-BENCHMARK_PAGE>
+```
+
+INP analysis requires a trace with a supported navigation/interaction insight. Selector statistics require a trace captured with `OPENCODE_PERFORMANCE_SELECTOR_TRACE=1`.
+
+`e2e/performance/playwright.uncapped.config.ts` disables Chromium frame-rate limiting for explicit uncapped diagnostics. Native product benchmarks should use the default Playwright configuration.

packages/app/e2e/performance/benchmark.ts

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+import { expect, test as base, type Browser, type Page, type TestInfo } from "@playwright/test"
+import { startChromeTrace } from "./chrome-trace"
+
+type BenchmarkFixtures = {
+  report: (metrics: Record<string, unknown>, context?: Record<string, unknown>) => void
+  reportState: { payload?: { metrics: Record<string, unknown>; context: Record<string, unknown> } }
+  benchmarkResult: void
+}
+
+export type PerformancePageDiagnostics = {
+  navigations: string[]
+  stop: () => Promise<string | undefined>
+}
+
+const pages = new WeakMap<Page, PerformancePageDiagnostics>()
+
+export const benchmark = base.extend<BenchmarkFixtures>({
+  reportState: async ({}, use) => use({}),
+  report: async ({ reportState }, use) => {
+    await use((metrics, context = {}) => {
+      if (reportState.payload) throw new Error("Benchmark reported metrics more than once")
+      reportState.payload = { metrics, context }
+    })
+  },
+  benchmarkResult: [
+    async ({ reportState }, use, testInfo) => {
+      await use()
+      const missing = !reportState.payload
+      console.log(
+        `BENCHMARK ${JSON.stringify({
+          schemaVersion: 2,
+          runID: process.env.OPENCODE_PERFORMANCE_RUN_ID,
+          name: benchmarkName(testInfo),
+          status: missing ? "failed" : testInfo.status,
+          expectedStatus: testInfo.expectedStatus,
+          retry: testInfo.retry,
+          repeatEachIndex: testInfo.repeatEachIndex,
+          context: {
+            project: testInfo.project.name,
+            platform: process.platform,
+            ...reportState.payload?.context,
+          },
+          metrics: reportState.payload?.metrics ?? null,
+          error: missing ? "Benchmark did not report metrics" : undefined,
+        })}`,
+      )
+      if (missing && testInfo.status === testInfo.expectedStatus)
+        throw new Error(`Benchmark did not report metrics: ${benchmarkName(testInfo)}`)
+    },
+    { auto: true },
+  ],
+  page: async ({ page }, use, testInfo) => {
+    const name = benchmarkName(testInfo)
+    const diagnostics = await observePerformancePage(page, name)
+    try {
+      await use(page)
+    } finally {
+      try {
+        await reportPerformancePage(name, diagnostics, testInfo)
+      } finally {
+        if (testInfo.status !== testInfo.expectedStatus) {
+          await testInfo.attach("performance-navigations", {
+            body: JSON.stringify(diagnostics.navigations, null, 2),
+            contentType: "application/json",
+          })
+        }
+      }
+    }
+  },
+})
+
+function benchmarkName(testInfo: TestInfo) {
+  return testInfo.titlePath.slice(1).join(" > ")
+}
+
+export { expect }
+
+async function observePerformancePage(page: Page, name: string) {
+  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 stopping: Promise<string | undefined> | undefined
+  const diagnostics: PerformancePageDiagnostics = {
+    navigations,
+    stop() {
+      page.off("framenavigated", onNavigation)
+      return (stopping ??= stopTrace?.() ?? Promise.resolve(undefined))
+    },
+  }
+  pages.set(page, diagnostics)
+  return diagnostics
+}
+
+export async function withBenchmarkPage<T>(
+  browser: Browser,
+  name: string,
+  run: (page: Page) => Promise<T>,
+  testInfo?: TestInfo,
+) {
+  const context = await browser.newContext()
+  try {
+    const page = await context.newPage()
+    const diagnostics = await observePerformancePage(page, name)
+    try {
+      return await run(page)
+    } finally {
+      await reportPerformancePage(name, diagnostics, testInfo)
+    }
+  } finally {
+    await context.close()
+  }
+}
+
+async function reportPerformancePage(name: string, diagnostics: PerformancePageDiagnostics, testInfo?: TestInfo) {
+  const trace = await diagnostics.stop()
+  console.log(
+    `BENCHMARK_PAGE ${JSON.stringify({
+      schemaVersion: 2,
+      runID: process.env.OPENCODE_PERFORMANCE_RUN_ID,
+      name,
+      test: testInfo ? benchmarkName(testInfo) : undefined,
+      retry: testInfo?.retry,
+      repeatEachIndex: testInfo?.repeatEachIndex,
+      context: {
+        platform: process.platform,
+        trace,
+        selectorTrace: process.env.OPENCODE_PERFORMANCE_SELECTOR_TRACE === "1",
+      },
+      navigations: diagnostics.navigations,
+    })}`,
+  )
+}
+
+export function benchmarkDiagnostics(page: Page) {
+  const diagnostics = pages.get(page)
+  if (!diagnostics) throw new Error("Performance diagnostics are not installed for this page")
+  return diagnostics
+}

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

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+import type { CDPSession, Page } from "@playwright/test"
+import path from "node:path"
+import { mkdir, open, rename } from "node:fs/promises"
+import { Buffer } from "node:buffer"
+import { createHash, randomUUID } from "node:crypto"
+
+const categories = [
+  "-*",
+  "devtools.timeline",
+  "v8.execute",
+  "disabled-by-default-devtools.timeline",
+  "disabled-by-default-devtools.timeline.frame",
+  "toplevel",
+  "blink.console",
+  "blink.user_timing",
+  "latencyInfo",
+  "disabled-by-default-devtools.timeline.stack",
+  "disabled-by-default-v8.cpu_profiler",
+]
+
+export async function startChromeTrace(page: Page, name: string) {
+  const directory = process.env.OPENCODE_PERFORMANCE_TRACE_DIR
+  if (!directory) return
+
+  const selectors = process.env.OPENCODE_PERFORMANCE_SELECTOR_TRACE === "1"
+  const file = await prepareChromeTrace(directory, name, selectors)
+  const session = await page.context().newCDPSession(page)
+  try {
+    await session.send("Tracing.start", {
+      transferMode: "ReturnAsStream",
+      traceConfig: {
+        excludedCategories: categories
+          .filter((category) => category.startsWith("-"))
+          .map((category) => category.slice(1)),
+        includedCategories: [
+          ...categories.filter((category) => !category.startsWith("-")),
+          ...(selectors
+            ? ["disabled-by-default-blink.debug", "disabled-by-default-devtools.timeline.invalidationTracking"]
+            : []),
+        ],
+      },
+    })
+  } catch (error) {
+    await Promise.allSettled([session.detach()])
+    throw error
+  }
+  let stopping: Promise<string> | undefined
+
+  return () =>
+    (stopping ??= (async () => {
+      try {
+        const complete = new Promise<{ stream?: string; dataLossOccurred: boolean }>((resolve) =>
+          session.once("Tracing.tracingComplete", resolve),
+        )
+        await session.send("Tracing.end")
+        const result = await complete
+        if (!result.stream) throw new Error(`Chrome trace stream missing: ${file}`)
+        const partial = `${file}.partial`
+        await writeProtocolStream(session, result.stream, partial)
+        if (result.dataLossOccurred) throw new Error(`Chrome trace lost data; partial capture retained: ${partial}`)
+        await rename(partial, file)
+        return file
+      } finally {
+        await Promise.allSettled([session.detach()])
+      }
+    })())
+}
+
+export async function prepareChromeTrace(
+  directory: string,
+  name: string,
+  selectors: boolean,
+  nonce = randomUUID().slice(0, 8),
+) {
+  await mkdir(directory, { recursive: true })
+  const run = process.env.OPENCODE_PERFORMANCE_RUN_ID ?? "manual"
+  const hash = createHash("sha256").update(name).digest("hex").slice(0, 8)
+  return path.join(
+    directory,
+    `${run}-${name.replace(/[^a-zA-Z0-9_-]/g, "-")}-${hash}-${nonce}${selectors ? "-selectors" : ""}.json`,
+  )
+}
+
+async function writeProtocolStream(session: CDPSession, handle: string, file: string) {
+  const output = await open(file, "wx")
+  try {
+    while (true) {
+      const chunk = await session.send("IO.read", { handle })
+      await output.write(chunk.base64Encoded ? Buffer.from(chunk.data, "base64") : chunk.data)
+      if (chunk.eof) break
+    }
+  } finally {
+    await Promise.allSettled([output.close(), session.send("IO.close", { handle })])
+  }
+}

packages/app/e2e/performance/playwright.config.ts

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+import config from "../../playwright.config"
+
+const port = Number(process.env.PLAYWRIGHT_PORT ?? 3000)
+process.env.PLAYWRIGHT_SERVER_PORT = String(port)
+process.env.OPENCODE_PERFORMANCE_RUN_ID ??= `${new Date().toISOString().replace(/[:.]/g, "-")}-${process.pid}`
+
+export default {
+  ...config,
+  testDir: ".",
+  testIgnore: "unit/**",
+  outputDir: "../test-results/performance",
+  fullyParallel: false,
+  workers: 1,
+  reporter: [["html", { outputFolder: "../playwright-report/performance", open: "never" }], ["line"]],
+  webServer: {
+    ...config.webServer,
+    command: `bun run build && bun run serve -- --host 0.0.0.0 --port ${port} --strictPort`,
+    reuseExistingServer: false,
+  },
+}

packages/app/e2e/performance/playwright.uncapped.config.ts

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+import config from "./playwright.config"
+
+export default {
+  ...config,
+  outputDir: "../test-results/performance-uncapped",
+  reporter: [["html", { outputFolder: "../playwright-report/performance-uncapped", open: "never" }], ["line"]],
+  use: {
+    ...config.use,
+    launchOptions: {
+      args: ["--disable-frame-rate-limit", "--disable-gpu-vsync"],
+    },
+  },
+}

packages/app/e2e/performance/unit/session-timeline-stream-probe.test.ts

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+import { expect, test } from "bun:test"
+import { streamChunk } from "../timeline/session-timeline-benchmark.fixture"
+import { streamProgress } from "../timeline/session-timeline-stream-probe"
+
+test("classifies emitted stream markers using the fixture cycle", () => {
+  expect(streamProgress("before stream-17 after stream-18")).toEqual({ index: 18, phase: "boundary" })
+  expect(streamProgress("before stream-18 after stream-19")).toEqual({ index: 19, phase: "stream" })
+  expect(streamProgress("benchmark-complete stream-36")).toEqual({ index: 36, phase: "complete" })
+  expect(streamProgress("no marker")).toEqual({ index: -1, phase: "unknown" })
+})
+
+test("emits progress markers at fixture boundaries", () => {
+  expect(streamProgress(streamChunk(18, 160))).toEqual({ index: 18, phase: "boundary" })
+})

packages/app/e2e/performance/unit/session-timeline-visual-tracking.test.ts

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+import { expect, test } from "bun:test"
+import { layoutShiftValue, removeVisibleRow } from "../timeline/session-timeline-stream-probe"
+
+test("excludes layout shifts before the probe window and recent input", () => {
+  expect(layoutShiftValue({ startTime: 9, value: 0.1 }, 10)).toBeUndefined()
+  expect(layoutShiftValue({ startTime: 10, value: 0.2, hadRecentInput: true }, 10)).toBeUndefined()
+  expect(layoutShiftValue({ startTime: 11, value: 0.3 }, 10)).toBe(0.3)
+})
+
+test("classifies removed rows from their last painted visibility", () => {
+  const row = {}
+  const visible = new Set([row])
+
+  expect(removeVisibleRow(visible, row)).toBe(true)
+  expect(removeVisibleRow(visible, row)).toBe(false)
+})

packages/app/e2e/regression/cross-server-tab-close.spec.ts

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+import { expect, test, type Page, type Route } from "@playwright/test"
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { currentSession } from "../utils/mock-server"
+
+const serverA = "http://127.0.0.1:4096"
+const serverB = "http://127.0.0.1:4097"
+const sessionA = session("ses_server_a", "C:/server-a", "Server A session")
+const sessionB = session("ses_server_b", "/home/server-b", "Server B session")
+
+test("closing the active server's last tab opens the remaining server tab", async ({ page }) => {
+  const requests: string[] = []
+  await mockServers(page, requests)
+  await page.addInitScript(
+    ({ serverB, sessionA, sessionB }) => {
+      localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: true } }))
+      localStorage.setItem("opencode.global.dat:server", JSON.stringify({ list: [serverB] }))
+      localStorage.setItem(
+        "opencode.window.browser.dat:tabs",
+        JSON.stringify([
+          { type: "session", server: "http://127.0.0.1:4096", sessionId: sessionA },
+          { type: "session", server: serverB, sessionId: sessionB },
+        ]),
+      )
+    },
+    { serverB, sessionA: sessionA.id, sessionB: sessionB.id },
+  )
+
+  const hrefA = `/server/${base64Encode(serverA)}/session/${sessionA.id}`
+  const hrefB = `/server/${base64Encode(serverB)}/session/${sessionB.id}`
+  await page.goto(hrefA)
+  await expect(page.getByText(sessionA.title).first()).toBeVisible()
+
+  const tabA = page.locator(`[data-titlebar-tab-slot]:has(a[href="${hrefA}"])`)
+  await tabA.locator('[data-slot="tab-close"] button').click()
+
+  await expect(page).toHaveURL(new RegExp(`${hrefB.replace(/[.*+?^${}()|[\]\\]/g, "\\$&")}$`))
+  await expect.poll(() => requests.some((url) => url.startsWith(`${serverB}/api/session/${sessionB.id}`))).toBe(true)
+  await expect(page.getByText(sessionB.title).first()).toBeVisible()
+  const sessionBRequests = requests.filter((url) => url.includes(`/session/${sessionB.id}`))
+  expect(sessionBRequests.every((url) => url.startsWith(serverB))).toBe(true)
+  expect(
+    requests.some((request) => {
+      const url = new URL(request)
+      return url.origin === serverB && url.searchParams.get("directory") === sessionB.directory
+    }),
+  ).toBe(true)
+})
+
+test("legacy session routes preserve an existing tab's server", async ({ page }) => {
+  await mockServers(page, [])
+  await page.addInitScript(
+    ({ serverB, sessionB }) => {
+      localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: true } }))
+      localStorage.setItem("opencode.global.dat:server", JSON.stringify({ list: [serverB] }))
+      localStorage.setItem(
+        "opencode.window.browser.dat:tabs",
+        JSON.stringify([{ type: "session", server: serverB, sessionId: sessionB }]),
+      )
+    },
+    { serverB, sessionB: sessionB.id },
+  )
+
+  const hrefB = `/server/${base64Encode(serverB)}/session/${sessionB.id}`
+  await page.goto(`/${base64Encode(sessionB.directory)}/session/${sessionB.id}`)
+  await expect(page).toHaveURL(new RegExp(`${hrefB.replace(/[.*+?^${}()|[\]\\]/g, "\\$&")}$`))
+})
+
+function session(id: string, directory: string, title: string) {
+  return {
+    id,
+    slug: id,
+    projectID: `project-${id}`,
+    directory,
+    title,
+    version: "dev",
+    time: { created: 1, updated: 1 },
+  }
+}
+
+async function mockServers(page: Page, requests: string[]) {
+  await page.route("**/*", async (route) => {
+    const url = new URL(route.request().url())
+    if (url.origin !== serverA && url.origin !== serverB) return route.fallback()
+    requests.push(url.toString())
+    const current = url.origin === serverA ? sessionA : sessionB
+    const directory = url.searchParams.get("directory")
+    if (directory && directory !== current.directory) return json(route, { name: "InvalidDirectory" }, 500)
+    if (url.pathname === "/global/event" || url.pathname === "/event" || url.pathname === "/api/event")
+      return sse(route)
+    if (url.pathname === "/global/health") return json(route, {}, 404)
+    if (url.pathname === "/api/health") return json(route, { pid: 1 })
+    if (url.pathname === "/api/session") return json(route, { data: [currentSession(current)], cursor: {} })
+    if (url.pathname === "/api/session/active") return json(route, { data: {} })
+    if (url.pathname === `/api/session/${current.id}`) return json(route, { data: currentSession(current) })
+    if (url.pathname === `/api/session/${current.id}/message`) return json(route, { data: [], cursor: {} })
+    if (url.pathname === `/session/${current.id}`) return json(route, current)
+    if (/^\/session\/[^/]+$/.test(url.pathname)) return json(route, { name: "NotFoundError" }, 404)
+    if (url.pathname === `/session/${current.id}/message`) return json(route, [])
+    if (/^\/session\/[^/]+\/(children|todo|diff)$/.test(url.pathname)) return json(route, [])
+    if (["/skill", "/command", "/lsp", "/formatter", "/permission", "/question", "/vcs/diff"].includes(url.pathname))
+      return json(route, [])
+    if (["/global/config", "/config", "/provider/auth", "/mcp"].includes(url.pathname)) return json(route, {})
+    if (url.pathname === "/provider")
+      return json(route, { all: [], connected: [], default: { providerID: "", modelID: "" } })
+    if (url.pathname === "/agent") return json(route, [{ name: "build", mode: "primary" }])
+    if (url.pathname === "/project" || url.pathname === "/project/current") {
+      const project = {
+        id: current.projectID,
+        worktree: current.directory,
+        vcs: "git",
+        time: { created: 1, updated: 1 },
+        sandboxes: [],
+      }
+      return json(route, url.pathname === "/project" ? [project] : project)
+    }
+    if (url.pathname === "/path")
+      return json(route, {
+        state: current.directory,
+        config: current.directory,
+        worktree: current.directory,
+        directory: current.directory,
+        home: current.directory,
+      })
+    if (url.pathname === "/api/path")
+      return json(route, {
+        state: current.directory,
+        config: current.directory,
+        worktree: current.directory,
+        directory: current.directory,
+        home: current.directory,
+      })
+    if (url.pathname === "/vcs") return json(route, { branch: "main", default_branch: "main" })
+    if (url.pathname === "/api/vcs")
+      return json(route, {
+        location: { directory: current.directory },
+        data: { branch: "main", defaultBranch: "main" },
+      })
+    return json(route, {})
+  })
+}
+
+function json(route: Route, body: unknown, status = 200) {
+  return route.fulfill({
+    status,
+    contentType: "application/json",
+    headers: { "access-control-allow-origin": "*" },
+    body: JSON.stringify(body),
+  })
+}
+
+function sse(route: Route) {
+  return route.fulfill({ status: 200, contentType: "text/event-stream", body: ": ok\n\n" })
+}

packages/app/e2e/regression/file-browser-sidebar-tab-switch.spec.ts

@@ -0,0 +1,187 @@
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { expect, test, type Page } from "@playwright/test"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectSessionTitle } from "../utils/waits"
+
+const directory = "C:/OpenCode/FileBrowserSidebar"
+const projectID = "proj_file_browser_sidebar"
+const sessionID = "ses_file_browser_sidebar"
+const title = "File browser sidebar"
+const server = `http://${process.env.PLAYWRIGHT_SERVER_HOST ?? "127.0.0.1"}:${process.env.PLAYWRIGHT_SERVER_PORT ?? "4096"}`
+const files = Array.from({ length: 80 }, (_, index) => `file-${String(index).padStart(2, "0")}.ts`)
+// Marks the file-browser sidebar DOM node so a remount (fresh node) is detectable.
+const PROBE = "original"
+
+test.use({ viewport: { width: 1440, height: 900 } })
+
+// The file-browser sidebar must stay mounted across preview/pinned file-tab
+// switches. Remounting resets scroll and filter state.
+test("keeps the file-browser sidebar mounted when switching file tabs", async ({ page }) => {
+  await setup(page)
+
+  await page.goto(`/server/${base64Encode(server)}/session/${sessionID}`)
+  await expectSessionTitle(page, title)
+
+  const panel = page.locator("#review-panel")
+  await panel.getByRole("button", { name: "Open file" }).click()
+  await expect(panel.getByRole("tab", { name: "Open file" })).toHaveAttribute("data-selected", "")
+
+  const sidebar = panel.locator('[data-component="session-review-v2-sidebar-root"]')
+  await expect(sidebar).toBeVisible()
+  await expect(panel.getByRole("button", { name: "file-00.ts" })).toBeVisible()
+
+  await panel.getByRole("button", { name: "file-00.ts" }).click()
+  await expect(panel.getByRole("tab", { name: "file-00.ts" })).toHaveAttribute("data-selected", "")
+  await expect(panel.getByText("contents:file-00.ts", { exact: true })).toBeVisible()
+
+  const viewport = panel.locator('[data-slot="session-review-v2-sidebar-tree"] .scroll-view__viewport')
+  await viewport.hover()
+  await page.mouse.wheel(0, 100_000)
+  await expect
+    .poll(() => viewport.evaluate((element) => element.scrollHeight - element.clientHeight - element.scrollTop))
+    .toBeLessThanOrEqual(1)
+  const scrolled = await viewport.evaluate((element) => element.scrollTop)
+  expect(scrolled).toBeGreaterThan(0)
+  await writeProbe(page)
+
+  await panel.getByRole("button", { name: "file-79.ts" }).click()
+  await expect(panel.getByRole("tab", { name: "file-79.ts" })).toHaveAttribute("data-selected", "")
+  await expect(panel.getByText("contents:file-79.ts", { exact: true })).toBeVisible()
+  expect(await readProbe(page)).toBe(PROBE)
+  await expect.poll(() => viewport.evaluate((element) => element.scrollTop)).toBe(scrolled)
+
+  await panel.getByRole("button", { name: "file-78.ts" }).dblclick()
+  await expect(panel.getByRole("tab", { name: "file-78.ts" })).toHaveAttribute("data-selected", "")
+  await panel.getByRole("button", { name: "file-79.ts" }).click()
+  await expect(panel.getByRole("tab", { name: "file-79.ts" })).toHaveAttribute("data-selected", "")
+  await panel.getByRole("tab", { name: "file-78.ts" }).click()
+  await expect(panel.getByRole("tab", { name: "file-78.ts" })).toHaveAttribute("data-selected", "")
+  expect(await readProbe(page)).toBe(PROBE)
+  await expect.poll(() => viewport.evaluate((element) => element.scrollTop)).toBe(scrolled)
+})
+
+test("keeps previous file search results visible while the next search loads", async ({ page }) => {
+  const searchPending = Promise.withResolvers<void>()
+  await setup(page, async ({ query }) => {
+    if (query === "file-0") return ["file-00.ts"]
+    if (query === "file-7") {
+      await searchPending.promise
+      return ["file-79.ts"]
+    }
+    return []
+  })
+
+  await page.goto(`/server/${base64Encode(server)}/session/${sessionID}`)
+  await expectSessionTitle(page, title)
+
+  const panel = page.locator("#review-panel")
+  await panel.getByRole("button", { name: "Open file" }).click()
+  const filter = panel.getByRole("combobox", { name: "Filter files" })
+  await filter.fill("file-0")
+  await expect(panel.getByRole("option", { name: "file-00.ts" })).toBeVisible()
+
+  const nextSearch = page.waitForRequest((request) => {
+    const url = new URL(request.url())
+    return url.pathname === "/find/file" && url.searchParams.get("query") === "file-7"
+  })
+  await filter.fill("file-7")
+  await nextSearch
+  await expect(panel.getByRole("option", { name: "file-00.ts" })).toBeVisible()
+
+  searchPending.resolve()
+  await expect(panel.getByRole("option", { name: "file-79.ts" })).toBeVisible()
+  await expect(panel.getByRole("option", { name: "file-00.ts" })).toBeHidden()
+})
+
+type Probed = HTMLElement & { __e2eProbe?: string }
+
+async function writeProbe(page: Page) {
+  await page.locator('#review-panel [data-component="session-review-v2-sidebar-root"]').evaluate((el, probe) => {
+    ;(el as Probed).__e2eProbe = probe
+  }, PROBE)
+}
+
+async function readProbe(page: Page) {
+  return page
+    .locator('#review-panel [data-component="session-review-v2-sidebar-root"]')
+    .evaluate((el) => (el as Probed).__e2eProbe)
+}
+
+async function setup(
+  page: Page,
+  findFiles?: (input: { query: string; dirs?: string; limit?: number }) => unknown | Promise<unknown>,
+) {
+  await mockOpenCodeServer(page, {
+    directory,
+    project: {
+      id: projectID,
+      worktree: directory,
+      vcs: "git",
+      name: "file-browser-sidebar",
+      time: { created: 1700000000000, updated: 1700000000000 },
+      sandboxes: [],
+    },
+    provider: {
+      all: [
+        {
+          id: "opencode",
+          name: "OpenCode",
+          models: { test: { id: "test", name: "Test", limit: { context: 200_000 } } },
+        },
+      ],
+      connected: ["opencode"],
+      default: { providerID: "opencode", modelID: "test" },
+    },
+    sessions: [
+      {
+        id: sessionID,
+        slug: sessionID,
+        projectID,
+        directory,
+        title,
+        version: "dev",
+        time: { created: 1700000000000, updated: 1700000000000 },
+      },
+    ],
+    vcsDiff: [],
+    fileList: (path) => {
+      if (path) return []
+      return files.map((name) => ({
+        name,
+        path: name,
+        absolute: `${directory}/${name}`,
+        type: "file" as const,
+        ignored: false,
+      }))
+    },
+    fileContent: (path) => ({ type: "text", content: `contents:${path}` }),
+    findFiles,
+    pageMessages: () => ({ items: [] }),
+  })
+
+  await page.addInitScript(
+    ({ directory, server, sessionID }) => {
+      localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: true } }))
+      localStorage.setItem(
+        "opencode.global.dat:server",
+        JSON.stringify({
+          projects: { local: [{ worktree: directory, expanded: true }] },
+          lastProject: { local: directory },
+        }),
+      )
+      localStorage.setItem(
+        "opencode.global.dat:layout",
+        JSON.stringify({ review: { diffStyle: "split", panelOpened: true } }),
+      )
+      localStorage.setItem(
+        "opencode.global.dat:review-panel-v2",
+        JSON.stringify({ sidebarOpened: true, sidebarWidth: 240, expandMode: "collapse" }),
+      )
+      localStorage.setItem(
+        "opencode.window.browser.dat:tabs",
+        JSON.stringify([{ type: "session", server, sessionId: sessionID }]),
+      )
+    },
+    { directory, server, sessionID },
+  )
+}

packages/app/e2e/regression/new-session-panel-corner.spec.ts

@@ -0,0 +1,83 @@
+import { expect, test } from "@playwright/test"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectAppVisible } from "../utils/waits"
+
+const draftID = "draft_new_session_panel_corner"
+const directory = "C:/OpenCode/NewSessionPanelCorner"
+const server = `http://${process.env.PLAYWRIGHT_SERVER_HOST ?? "127.0.0.1"}:${process.env.PLAYWRIGHT_SERVER_PORT ?? "4096"}`
+
+test.use({
+  viewport: { width: 935, height: 522 },
+  deviceScaleFactor: 1,
+})
+
+test("matches the rounded panel corners to the dark new-session background", async ({ page }, testInfo) => {
+  await mockOpenCodeServer(page, {
+    directory,
+    project: {
+      id: "proj_new_session_panel_corner",
+      worktree: directory,
+      vcs: "git",
+      name: "new-session-panel-corner",
+      time: { created: 1700000000000, updated: 1700000000000 },
+      sandboxes: [],
+    },
+    provider: { all: [], connected: [], default: {} },
+    sessions: [],
+    pageMessages: () => ({ items: [] }),
+  })
+  await page.addInitScript(
+    ({ directory, draftID, server }) => {
+      localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: true } }))
+      localStorage.setItem("opencode-theme-id", "oc-2")
+      localStorage.setItem("opencode-color-scheme", "dark")
+      localStorage.setItem(
+        "opencode.global.dat:server",
+        JSON.stringify({
+          projects: { local: [{ worktree: directory, expanded: true }] },
+          lastProject: { local: directory },
+        }),
+      )
+      localStorage.setItem(
+        "opencode.window.browser.dat:tabs",
+        JSON.stringify([{ type: "draft", draftID, server, directory }]),
+      )
+    },
+    { directory, draftID, server },
+  )
+
+  await page.goto(`/new-session?draftId=${draftID}`)
+  await expectAppVisible(page.locator('[data-component="prompt-input"]'))
+  await expect(page.locator("html")).toHaveAttribute("data-color-scheme", "dark")
+  const panel = page.locator('main div[class*="rounded-[10px]"][class*="overflow-hidden"]')
+  await expect(panel).toHaveCount(1)
+  const box = await panel.boundingBox()
+  if (!box) throw new Error("New-session panel bounds are unavailable")
+
+  const screenshot = await page.screenshot({ path: testInfo.outputPath("new-session-dark.png") })
+  const corners = await page.evaluate(
+    async ({ source, points }) => {
+      const image = new Image()
+      image.src = source
+      await image.decode()
+      const canvas = document.createElement("canvas")
+      canvas.width = image.naturalWidth
+      canvas.height = image.naturalHeight
+      const context = canvas.getContext("2d")
+      if (!context) throw new Error("2D canvas is unavailable")
+      context.drawImage(image, 0, 0)
+      return points.map((point) => Array.from(context.getImageData(point.x, point.y, 1, 1).data))
+    },
+    {
+      source: `data:image/png;base64,${screenshot.toString("base64")}`,
+      points: [
+        { x: Math.floor(box.x), y: Math.floor(box.y) },
+        { x: Math.ceil(box.x + box.width) - 1, y: Math.floor(box.y) },
+        { x: Math.floor(box.x), y: Math.ceil(box.y + box.height) - 1 },
+        { x: Math.ceil(box.x + box.width) - 1, y: Math.ceil(box.y + box.height) - 1 },
+      ],
+    },
+  )
+
+  expect(corners.every(([red, green, blue, alpha]) => red <= 8 && green <= 8 && blue <= 8 && alpha === 255)).toBe(true)
+})

packages/app/e2e/regression/open-file-expand-folder.spec.ts

@@ -0,0 +1,132 @@
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { expect, test } from "@playwright/test"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectSessionTitle } from "../utils/waits"
+
+const directory = "C:/OpenCode/OpenFileExpand"
+const projectID = "proj_open_file_expand"
+const sessionID = "ses_open_file_expand"
+const title = "Open file expand"
+const server = `http://${process.env.PLAYWRIGHT_SERVER_HOST ?? "127.0.0.1"}:${process.env.PLAYWRIGHT_SERVER_PORT ?? "4096"}`
+
+test.use({ viewport: { width: 1440, height: 900 } })
+
+test("expands a folder whose path has a trailing Windows separator", async ({ page }) => {
+  await mockOpenCodeServer(page, {
+    directory,
+    project: {
+      id: projectID,
+      worktree: directory,
+      vcs: "git",
+      name: "open-file-expand",
+      time: { created: 1700000000000, updated: 1700000000000 },
+      sandboxes: [],
+    },
+    provider: {
+      all: [
+        {
+          id: "opencode",
+          name: "OpenCode",
+          models: { test: { id: "test", name: "Test", limit: { context: 200_000 } } },
+        },
+      ],
+      connected: ["opencode"],
+      default: { providerID: "opencode", modelID: "test" },
+    },
+    sessions: [
+      {
+        id: sessionID,
+        slug: sessionID,
+        projectID,
+        directory,
+        title,
+        version: "dev",
+        time: { created: 1700000000000, updated: 1700000000000 },
+      },
+    ],
+    vcsDiff: [],
+    fileList: (path) => {
+      if (path === "frontend\\" || path === "frontend") {
+        return [
+          {
+            name: "app.ts",
+            path: "frontend\\app.ts",
+            absolute: `${directory}/frontend/app.ts`,
+            type: "file" as const,
+            ignored: false,
+          },
+        ]
+      }
+      if (path) return []
+      return [
+        {
+          name: "frontend",
+          path: "frontend\\",
+          absolute: `${directory}/frontend`,
+          type: "directory" as const,
+          ignored: false,
+        },
+        {
+          name: "README.md",
+          path: "README.md",
+          absolute: `${directory}/README.md`,
+          type: "file" as const,
+          ignored: false,
+        },
+      ]
+    },
+    fileContent: (path) => ({ type: "text", content: `contents:${path}` }),
+    pageMessages: () => ({ items: [] }),
+  })
+
+  await page.addInitScript(
+    ({ directory, server, sessionID }) => {
+      localStorage.setItem(
+        "settings.v3",
+        JSON.stringify({ general: { newLayoutDesigns: true, shouldDisplayTabsToast: false } }),
+      )
+      localStorage.setItem(
+        "opencode.global.dat:server",
+        JSON.stringify({
+          projects: { local: [{ worktree: directory, expanded: true }] },
+          lastProject: { local: directory },
+        }),
+      )
+      localStorage.setItem(
+        "opencode.global.dat:layout",
+        JSON.stringify({ review: { diffStyle: "split", panelOpened: true } }),
+      )
+      localStorage.setItem(
+        "opencode.global.dat:review-panel-v2",
+        JSON.stringify({ sidebarOpened: true, sidebarWidth: 240, expandMode: "collapse" }),
+      )
+      localStorage.setItem(
+        "opencode.window.browser.dat:tabs",
+        JSON.stringify([{ type: "session", server, sessionId: sessionID }]),
+      )
+    },
+    { directory, server, sessionID },
+  )
+
+  await page.goto(`/server/${base64Encode(server)}/session/${sessionID}`)
+  await expectSessionTitle(page, title)
+
+  const panel = page.locator("#review-panel")
+  await panel.getByRole("button", { name: "Open file" }).click()
+  await expect(panel.getByRole("tab", { name: "Open file" })).toHaveAttribute("data-selected", "")
+
+  const sidebar = panel.locator('[data-component="session-review-v2-sidebar-root"]')
+  await expect(sidebar).toBeVisible()
+
+  const frontendRow = panel.locator('[data-slot="file-tree-v2-row"][data-path="frontend"]')
+  await expect(frontendRow).toBeVisible()
+  await expect(frontendRow).toHaveAttribute("aria-expanded", "false")
+  await frontendRow.click()
+  await expect(frontendRow).toHaveAttribute("aria-expanded", "true")
+
+  const appRow = panel.locator('[data-slot="file-tree-v2-row"][data-path="frontend/app.ts"]')
+  await expect(appRow).toBeVisible()
+  await appRow.click()
+  await expect(panel.getByRole("tab", { name: "app.ts" })).toHaveAttribute("data-selected", "")
+  await expect(panel.getByText("contents:frontend/app.ts", { exact: true })).toBeVisible()
+})

packages/app/e2e/regression/project-picker-recent-search.spec.ts

@@ -0,0 +1,60 @@
+import { expect, test } from "@playwright/test"
+import type { Page } from "@playwright/test"
+import { fixture, pageMessages } from "../smoke/session-timeline.fixture"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectAppVisible } from "../utils/waits"
+
+const NAMES = ["alpha-service", "bravo-web", "charlie-api", "delta-tools", "echo-infra", "foxtrot-docs"]
+const worktrees = NAMES.map((name) => `/opencode-demo/${name}`)
+
+// The sixth project sits outside the five-item recent cap, so it is only reachable if the
+// dialog hands every recent project to the list filter instead of a pre-truncated slice.
+const OUTSIDE_CAP = "foxtrot-docs"
+
+// Dialog rows carry data-directory-path; the sidebar project list does not, so this
+// scopes assertions to the picker instead of matching the sidebar entry of the same name.
+const rows = (page: Page) => page.locator("[data-directory-path]")
+const row = (page: Page, name: string) => page.locator(`[data-directory-path*="${name}"]`)
+
+async function openProjectDialog(page: Page) {
+  await mockOpenCodeServer(page, {
+    sessions: fixture.sessions,
+    provider: fixture.provider,
+    directory: fixture.directory,
+    project: fixture.project,
+    pageMessages,
+    fileList: () => [],
+    findFiles: () => [],
+  })
+  await page.addInitScript((dirs) => {
+    localStorage.setItem(
+      "opencode.global.dat:server",
+      JSON.stringify({
+        projects: { local: dirs.map((worktree: string) => ({ worktree, expanded: false })) },
+        lastProject: {},
+      }),
+    )
+  }, worktrees)
+  await page.goto("/")
+  const add = page.getByRole("button", { name: "Add project" }).first()
+  await expectAppVisible(add)
+  await add.click()
+  await expect(rows(page)).toHaveCount(5)
+  return page.getByRole("textbox").last()
+}
+
+test("searches every recent project, not just the five most recent", async ({ page }) => {
+  const search = await openProjectDialog(page)
+  await expect(row(page, OUTSIDE_CAP)).toHaveCount(0)
+
+  await search.fill("foxtrot")
+
+  await expect(row(page, OUTSIDE_CAP)).toHaveCount(1)
+})
+
+test("still caps the idle recent list at five projects", async ({ page }) => {
+  await openProjectDialog(page)
+
+  await expect(row(page, NAMES[4])).toHaveCount(1)
+  await expect(row(page, OUTSIDE_CAP)).toHaveCount(0)
+})

packages/app/e2e/regression/prompt-input-v2-command-draft.spec.ts

@@ -0,0 +1,50 @@
+import { expect, test } from "@playwright/test"
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectAppVisible } from "../utils/waits"
+
+const directory = "C:/OpenCode/PromptInputV2Editing"
+const projectID = "proj_prompt_input_v2_editing"
+const sessionID = "ses_prompt_input_v2_editing"
+
+test("preserves the draft when a populated command menu triggers a built-in", async ({ page }) => {
+  await mockOpenCodeServer(page, {
+    directory,
+    project: {
+      id: projectID,
+      worktree: directory,
+      vcs: "git",
+      name: "prompt-input-v2-editing",
+      time: { created: 1700000000000, updated: 1700000000000 },
+      sandboxes: [],
+    },
+    provider: { all: [], connected: [], default: {} },
+    sessions: [
+      {
+        id: sessionID,
+        slug: "prompt-input-v2-editing",
+        projectID,
+        directory,
+        title: "Prompt input V2 editing",
+        version: "dev",
+        time: { created: 1700000000000, updated: 1700000000000 },
+      },
+    ],
+    pageMessages: () => ({ items: [] }),
+  })
+  await page.addInitScript(() => {
+    localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: true } }))
+  })
+
+  await page.goto(`/${base64Encode(directory)}/session/${sessionID}`)
+  const composer = page.locator('[data-component="prompt-input-v2"]')
+  const input = composer.locator('[data-component="prompt-input"]')
+  await expectAppVisible(composer)
+
+  await input.fill("keep me")
+  await composer.getByRole("button", { name: "Add images and files" }).click()
+  await page.getByRole("menuitem", { name: "Commands" }).click()
+  await page.locator('[data-suggestion-id="model.choose"]').click()
+
+  await expect(input).toHaveText("keep me")
+})

packages/app/e2e/regression/prompt-thinking-level.spec.ts

@@ -0,0 +1,84 @@
+import { expect, test, type Page } from "@playwright/test"
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectAppVisible } from "../utils/waits"
+
+const directory = "C:/OpenCode/PromptThinkingLevelRegression"
+const projectID = "proj_prompt_thinking_level_regression"
+const sessionID = "ses_prompt_thinking_level_regression"
+
+test("shows the V2 thinking level control while relevant", async ({ page }) => {
+  await mockOpenCodeServer(page, {
+    directory,
+    project: {
+      id: projectID,
+      worktree: directory,
+      vcs: "git",
+      name: "prompt-thinking-level-regression",
+      time: { created: 1700000000000, updated: 1700000000000 },
+      sandboxes: [],
+    },
+    provider: {
+      all: [
+        {
+          id: "opencode",
+          name: "OpenCode",
+          models: {
+            "thinking-model": {
+              id: "thinking-model",
+              name: "Thinking Model",
+              limit: { context: 200_000 },
+              variants: { high: {} },
+            },
+          },
+        },
+      ],
+      connected: ["opencode"],
+      default: { providerID: "opencode", modelID: "thinking-model" },
+    },
+    sessions: [
+      {
+        id: sessionID,
+        slug: "prompt-thinking-level-regression",
+        projectID,
+        directory,
+        title: "Prompt thinking level regression",
+        version: "dev",
+        time: { created: 1700000000000, updated: 1700000000000 },
+      },
+    ],
+    pageMessages: () => ({ items: [] }),
+  })
+  await page.addInitScript(() => {
+    localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: true } }))
+  })
+
+  await page.goto(`/${base64Encode(directory)}/session/${sessionID}`)
+  const composer = page.locator('[data-component="prompt-input-v2"]')
+  const input = composer.locator('[data-component="prompt-input"]')
+  const control = composer.getByRole("button", { name: "Choose model variant" })
+  await expectAppVisible(composer)
+
+  await idleComposer(page)
+  await expect(control).toBeVisible()
+
+  await control.click()
+  const high = page.getByRole("menuitemradio", { name: "high" })
+  await expect(high).toBeVisible()
+  await page.mouse.move(0, 0)
+  await expect(control).toBeVisible()
+  await expect(high).toBeVisible()
+  await high.click()
+
+  await idleComposer(page)
+  await input.focus()
+  await expect(control).toBeVisible()
+
+  await idleComposer(page)
+  await expect(control).toBeVisible()
+})
+
+async function idleComposer(page: Page) {
+  await page.mouse.move(0, 0)
+  await page.evaluate(() => (document.activeElement as HTMLElement | null)?.blur())
+}

packages/app/e2e/regression/remote-session-settings.spec.ts

@@ -0,0 +1,302 @@
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { expect, test, type Page, type Route } from "@playwright/test"
+import { installSseTransport } from "../utils/sse-transport"
+import { currentSession } from "../utils/mock-server"
+
+const serverA = "http://127.0.0.1:4096"
+const serverB = "http://127.0.0.1:4097"
+const directoryA = "C:/server-a"
+const directoryB = "/home/server-b"
+const sessionA = session("ses_server_a", directoryA, "Server A session")
+const childSessionA = { ...session("ses_server_a_child", directoryA, "Server A child session"), parentID: sessionA.id }
+const sessionB = session("ses_server_b", directoryB, "Server B session")
+
+test("session settings use the remote server context", async ({ page }) => {
+  const permissionRequests: string[] = []
+  await mockServers(page, permissionRequests)
+  await configureServers(page)
+
+  await page.goto(`/server/${base64Encode(serverB)}/session/${sessionB.id}`)
+  await expect(page.getByText(sessionB.title).first()).toBeVisible()
+  await page.keyboard.press("Control+,")
+
+  const dialog = page.locator(".settings-v2-dialog")
+  const autoAccept = dialog.locator('[data-action="settings-auto-accept-permissions"]')
+  const input = autoAccept.getByRole("switch")
+  await expect(autoAccept).toBeVisible()
+  await expect(input).toBeEnabled()
+  permissionRequests.length = 0
+  await autoAccept.locator('[data-slot="switch-control"]').click()
+  await expect(input).toBeChecked()
+  await expect
+    .poll(() =>
+      permissionRequests.some((request) => {
+        const url = new URL(request)
+        return url.origin === serverB && url.searchParams.get("directory") === directoryB
+      }),
+    )
+    .toBe(true)
+  expect(permissionRequests.every((request) => new URL(request).origin === serverB)).toBe(true)
+
+  await dialog.getByRole("tab", { name: "Models" }).click()
+  await expect(dialog.getByRole("switch", { name: "Server B Model" })).toBeEnabled()
+  await expect(dialog.getByRole("switch", { name: "Server A Model" })).toHaveCount(0)
+})
+
+test("auto-accept responds for an unfocused server session", async ({ page }) => {
+  const permissionRequests: string[] = []
+  const permissionResponses: PermissionResponse[] = []
+  const transport = await installSseTransport<{ directory: string; payload: Record<string, unknown> }>(page, {
+    server: serverA,
+    retry: 20,
+  })
+  await mockServers(page, permissionRequests, permissionResponses)
+  await configureServers(page, [
+    { type: "session", server: serverA, sessionId: sessionA.id },
+    { type: "session", server: serverB, sessionId: sessionB.id },
+  ])
+
+  const hrefB = `/server/${base64Encode(serverB)}/session/${sessionB.id}`
+  await page.goto(`/server/${base64Encode(serverA)}/session/${sessionA.id}`)
+  await expect(page.getByText(sessionA.title).first()).toBeVisible()
+  await page.keyboard.press("Control+,")
+  const autoAccept = page.locator(".settings-v2-dialog").locator('[data-action="settings-auto-accept-permissions"]')
+  await autoAccept.locator('[data-slot="switch-control"]').click()
+  await expect(autoAccept.getByRole("switch")).toBeChecked()
+  await expect
+    .poll(() =>
+      permissionRequests.some((request) => {
+        const url = new URL(request)
+        return url.origin === serverA && url.searchParams.get("directory") === directoryA
+      }),
+    )
+    .toBe(true)
+  await page.keyboard.press("Escape")
+
+  await page.locator(`[data-titlebar-tab-slot]:has(a[href="${hrefB}"])`).click()
+  await expect(page).toHaveURL(new RegExp(`${hrefB.replace(/[.*+?^${}()|[\]\\]/g, "\\$&")}$`))
+  await expect(page.getByText(sessionB.title).first()).toBeVisible()
+  await transport.waitForConnection()
+
+  await transport.send({
+    directory: directoryA,
+    payload: {
+      id: "event-permission-background-a",
+      type: "permission.asked",
+      properties: {
+        id: "permission-background-a",
+        sessionID: sessionA.id,
+        permission: "bash",
+        patterns: ["git status"],
+        metadata: {},
+        always: [],
+      },
+    },
+  })
+
+  await expect
+    .poll(() => permissionResponses)
+    .toEqual([
+      {
+        origin: serverA,
+        directory: directoryA,
+        sessionID: sessionA.id,
+        permissionID: "permission-background-a",
+        body: { response: "once" },
+      },
+    ])
+
+  await transport.send({
+    directory: directoryA,
+    payload: {
+      id: "event-permission-background-a-child",
+      type: "permission.asked",
+      properties: {
+        id: "permission-background-a-child",
+        sessionID: childSessionA.id,
+        permission: "bash",
+        patterns: ["git diff"],
+        metadata: {},
+        always: [],
+      },
+    },
+  })
+
+  await expect
+    .poll(() => permissionResponses)
+    .toEqual([
+      {
+        origin: serverA,
+        directory: directoryA,
+        sessionID: sessionA.id,
+        permissionID: "permission-background-a",
+        body: { response: "once" },
+      },
+      {
+        origin: serverA,
+        directory: directoryA,
+        sessionID: childSessionA.id,
+        permissionID: "permission-background-a-child",
+        body: { response: "once" },
+      },
+    ])
+})
+
+type PermissionResponse = {
+  origin: string
+  directory?: string
+  sessionID: string
+  permissionID: string
+  body: unknown
+}
+
+async function configureServers(page: Page, tabs: { type: "session"; server: string; sessionId: string }[] = []) {
+  await page.addInitScript(
+    ({ serverB, tabs }) => {
+      localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: true } }))
+      localStorage.setItem("opencode.global.dat:server", JSON.stringify({ list: [serverB] }))
+      localStorage.setItem("opencode.window.browser.dat:tabs", JSON.stringify(tabs))
+    },
+    { serverB, tabs },
+  )
+}
+
+async function mockServers(page: Page, permissionRequests: string[], permissionResponses: PermissionResponse[] = []) {
+  await page.route("**/*", async (route) => {
+    const url = new URL(route.request().url())
+    if (url.origin !== serverA && url.origin !== serverB) return route.fallback()
+    const remote = url.origin === serverB
+    const directory = remote ? directoryB : directoryA
+    const sessions = remote ? [sessionB] : [sessionA, childSessionA]
+    const requestDirectory = url.searchParams.get("directory")
+    const response = url.pathname.match(/^\/session\/([^/]+)\/permissions\/([^/]+)$/)
+    if (route.request().method() === "POST" && response) {
+      permissionResponses.push({
+        origin: url.origin,
+        directory: requestDirectory ?? undefined,
+        sessionID: response[1]!,
+        permissionID: response[2]!,
+        body: route.request().postDataJSON(),
+      })
+      return json(route, true)
+    }
+    if (requestDirectory && requestDirectory !== directory) return json(route, { name: "InvalidDirectory" }, 500)
+    if (url.pathname === "/global/event" || url.pathname === "/event" || url.pathname === "/api/event")
+      return sse(route)
+    if (url.pathname === "/global/health") return json(route, { healthy: true })
+    if (url.pathname === "/api/provider" || url.pathname === "/api/model" || url.pathname === "/api/agent")
+      return json(route, { data: [] })
+    if (url.pathname === "/api/model/default") return json(route, { data: null })
+    if (["/api/command", "/api/reference", "/api/permission/request", "/api/question/request"].includes(url.pathname))
+      return json(route, { location: { directory }, data: [] })
+    if (url.pathname === "/api/mcp") return json(route, { location: { directory }, data: [] })
+    if (url.pathname === "/api/mcp/resource")
+      return json(route, { location: { directory }, data: { resources: [], templates: [] } })
+    if (url.pathname === "/api/project") {
+      return json(route, [
+        {
+          id: remote ? sessionB.projectID : "project-server-a",
+          worktree: directory,
+          vcs: "git",
+          time: { created: 1, updated: 1 },
+          sandboxes: [],
+        },
+      ])
+    }
+    if (url.pathname === "/api/project/current")
+      return json(route, { id: remote ? sessionB.projectID : "project-server-a", directory })
+    if (url.pathname === "/api/session") return json(route, { data: sessions.map(currentSession), cursor: {} })
+    if (url.pathname === "/api/session/active") return json(route, { data: {} })
+    const currentSessionInfo = sessions.find((session) => url.pathname === `/api/session/${session.id}`)
+    if (currentSessionInfo) return json(route, { data: currentSession(currentSessionInfo) })
+    if (sessions.some((session) => url.pathname === `/api/session/${session.id}/message`))
+      return json(route, { data: [], cursor: {} })
+    const current = sessions.find((session) => url.pathname === `/session/${session.id}`)
+    if (current) return json(route, current)
+    if (/^\/session\/[^/]+$/.test(url.pathname)) return json(route, { name: "NotFoundError" }, 404)
+    if (/^\/session\/[^/]+\/message$/.test(url.pathname)) return json(route, [])
+    if (/^\/session\/[^/]+\/(children|todo|diff)$/.test(url.pathname)) return json(route, [])
+    if (url.pathname === "/permission") {
+      permissionRequests.push(url.toString())
+      return json(route, [])
+    }
+    if (["/skill", "/command", "/lsp", "/formatter", "/question", "/vcs/diff", "/pty/shells"].includes(url.pathname))
+      return json(route, [])
+    if (["/global/config", "/config", "/provider/auth", "/mcp"].includes(url.pathname)) return json(route, {})
+    if (url.pathname === "/provider") return json(route, provider(remote ? "server-b" : "server-a"))
+    if (url.pathname === "/agent") return json(route, [{ name: "build", mode: "primary" }])
+    if (url.pathname === "/project" || url.pathname === "/project/current") {
+      const project = {
+        id: remote ? sessionB.projectID : "project-server-a",
+        worktree: directory,
+        vcs: "git",
+        time: { created: 1, updated: 1 },
+        sandboxes: [],
+      }
+      return json(route, url.pathname === "/project" ? [project] : project)
+    }
+    if (url.pathname === "/path")
+      return json(route, {
+        state: directory,
+        config: directory,
+        worktree: directory,
+        directory,
+        home: directory,
+      })
+    if (url.pathname === "/api/path")
+      return json(route, { state: directory, config: directory, worktree: directory, directory, home: directory })
+    if (url.pathname === "/vcs") return json(route, { branch: "main", default_branch: "main" })
+    if (url.pathname === "/api/vcs")
+      return json(route, { location: { directory }, data: { branch: "main", defaultBranch: "main" } })
+    if (url.pathname === "/api/pty/shells") return json(route, { location: { directory }, data: [] })
+    return json(route, {})
+  })
+}
+
+function session(id: string, directory: string, title: string) {
+  return {
+    id,
+    slug: id,
+    projectID: `project-${id}`,
+    directory,
+    title,
+    version: "dev",
+    time: { created: 1, updated: 1 },
+  }
+}
+
+function provider(id: string) {
+  const name = id === "server-b" ? "Server B" : "Server A"
+  return {
+    all: [
+      {
+        id,
+        name: `${name} Provider`,
+        models: {
+          [id]: {
+            id,
+            name: `${name} Model`,
+            family: id,
+            release_date: "2026-01-01",
+            limit: { context: 200_000 },
+          },
+        },
+      },
+    ],
+    connected: [id],
+    default: { providerID: id, modelID: id },
+  }
+}
+
+function json(route: Route, body: unknown, status = 200) {
+  return route.fulfill({
+    status,
+    contentType: "application/json",
+    headers: { "access-control-allow-origin": "*" },
+    body: JSON.stringify(body),
+  })
+}
+
+function sse(route: Route) {
+  return route.fulfill({ status: 200, contentType: "text/event-stream", body: ": ok\n\n" })
+}

packages/app/e2e/regression/remote-tab-busy.spec.ts

@@ -0,0 +1,131 @@
+import { expect, test, type Page, type Route } from "@playwright/test"
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { currentSession } from "../utils/mock-server"
+
+const serverA = "http://127.0.0.1:4096"
+const serverB = "http://127.0.0.1:4097"
+const sessionA = session("ses_server_a", "C:/server-a", "Server A session")
+const sessionB = session("ses_server_b", "/home/server-b", "Server B session")
+
+test("tab busy indicator reflects the tab server's own session status", async ({ page }) => {
+  await mockServers(page)
+  await page.addInitScript(
+    ({ serverA, serverB, sessionA, sessionB }) => {
+      localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: true } }))
+      localStorage.setItem("opencode.global.dat:server", JSON.stringify({ list: [serverB] }))
+      localStorage.setItem(
+        "opencode.window.browser.dat:tabs",
+        JSON.stringify([
+          { type: "session", server: serverA, sessionId: sessionA },
+          { type: "session", server: serverB, sessionId: sessionB },
+        ]),
+      )
+    },
+    { serverA, serverB, sessionA: sessionA.id, sessionB: sessionB.id },
+  )
+
+  const hrefA = `/server/${base64Encode(serverA)}/session/${sessionA.id}`
+  const hrefB = `/server/${base64Encode(serverB)}/session/${sessionB.id}`
+  await page.goto(hrefA)
+  await expect(page.getByText(sessionA.title).first()).toBeVisible()
+
+  // Session B is busy on server B while server A stays the active server, so the
+  // busy indicator must come from the tab server's status, not the active server's.
+  const tabB = page.locator(`[data-titlebar-tab-slot]:has(a[href="${hrefB}"])`)
+  await expect(tabB.locator('[data-component="session-progress-indicator-v2"]')).toBeVisible()
+
+  const tabA = page.locator(`[data-titlebar-tab-slot]:has(a[href="${hrefA}"])`)
+  await expect(tabA.locator("[data-titlebar-tab-title]")).toHaveText(sessionA.title)
+  await expect(tabA.locator('[data-component="session-progress-indicator-v2"]')).toHaveCount(0)
+})
+
+function session(id: string, directory: string, title: string) {
+  return {
+    id,
+    slug: id,
+    projectID: `project-${id}`,
+    directory,
+    title,
+    version: "dev",
+    time: { created: 1, updated: 1 },
+  }
+}
+
+async function mockServers(page: Page) {
+  await page.route("**/*", async (route) => {
+    const url = new URL(route.request().url())
+    if (url.origin !== serverA && url.origin !== serverB) return route.fallback()
+    const current = url.origin === serverA ? sessionA : sessionB
+    const directory = url.searchParams.get("directory")
+    if (directory && directory !== current.directory) return json(route, { name: "InvalidDirectory" }, 500)
+    if (url.pathname === "/global/event" || url.pathname === "/event" || url.pathname === "/api/event")
+      return sse(route, url.pathname === "/api/event")
+    if (url.pathname === "/global/health") return json(route, {}, 404)
+    if (url.pathname === "/api/health") return json(route, { pid: 1 })
+    if (url.pathname === "/api/session/active")
+      return json(route, { data: url.origin === serverB ? { [sessionB.id]: { type: "running" } } : {} })
+    if (url.pathname === "/api/session") return json(route, { data: [currentSession(current)], cursor: {} })
+    if (url.pathname === `/api/session/${current.id}`) return json(route, { data: currentSession(current) })
+    if (url.pathname === `/api/session/${current.id}/message`) return json(route, { data: [], cursor: {} })
+    if (url.pathname === `/session/${current.id}`) return json(route, current)
+    if (/^\/session\/[^/]+$/.test(url.pathname)) return json(route, { name: "NotFoundError" }, 404)
+    if (url.pathname === `/session/${current.id}/message`) return json(route, [])
+    if (/^\/session\/[^/]+\/(children|todo|diff)$/.test(url.pathname)) return json(route, [])
+    if (["/skill", "/command", "/lsp", "/formatter", "/permission", "/question", "/vcs/diff"].includes(url.pathname))
+      return json(route, [])
+    if (["/global/config", "/config", "/provider/auth", "/mcp"].includes(url.pathname)) return json(route, {})
+    if (url.pathname === "/provider")
+      return json(route, { all: [], connected: [], default: { providerID: "", modelID: "" } })
+    if (url.pathname === "/agent") return json(route, [{ name: "build", mode: "primary" }])
+    if (url.pathname === "/project" || url.pathname === "/project/current") {
+      const project = {
+        id: current.projectID,
+        worktree: current.directory,
+        vcs: "git",
+        time: { created: 1, updated: 1 },
+        sandboxes: [],
+      }
+      return json(route, url.pathname === "/project" ? [project] : project)
+    }
+    if (url.pathname === "/path")
+      return json(route, {
+        state: current.directory,
+        config: current.directory,
+        worktree: current.directory,
+        directory: current.directory,
+        home: current.directory,
+      })
+    if (url.pathname === "/api/path")
+      return json(route, {
+        state: current.directory,
+        config: current.directory,
+        worktree: current.directory,
+        directory: current.directory,
+        home: current.directory,
+      })
+    if (url.pathname === "/vcs") return json(route, { branch: "main", default_branch: "main" })
+    if (url.pathname === "/api/vcs")
+      return json(route, {
+        location: { directory: current.directory },
+        data: { branch: "main", defaultBranch: "main" },
+      })
+    return json(route, {})
+  })
+}
+
+function json(route: Route, body: unknown, status = 200) {
+  return route.fulfill({
+    status,
+    contentType: "application/json",
+    headers: { "access-control-allow-origin": "*" },
+    body: JSON.stringify(body),
+  })
+}
+
+function sse(route: Route, current: boolean) {
+  return route.fulfill({
+    status: 200,
+    contentType: "text/event-stream",
+    body: current ? 'data: {"id":"evt_connected","type":"server.connected","data":{}}\n\n' : ": ok\n\n",
+  })
+}

packages/app/e2e/regression/review-image-flash.spec.ts

@@ -0,0 +1,202 @@
+import { expect, test, type Page } from "@playwright/test"
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectAppVisible, expectSessionTitle } from "../utils/waits"
+
+const directory = "C:/OpenCode/ReviewImageFlashRegression"
+const sessionID = "ses_review_image_flash_regression"
+const title = "Review image flash regression"
+const imageFile = "assets/preview.png"
+
+test("clicking an image file in the v2 review pane does not blank the panel", async ({ page }) => {
+  await openReview(page)
+  await installReviewFlashProbe(page)
+
+  await page.getByRole("button", { name: /preview\.png/ }).click()
+  await waitForReviewFlashProbe(page, 400)
+  const trace = await collectReviewFlashProbe(page)
+  const bad = trace.samples.filter((sample) => sample.blank || sample.blackCenter)
+
+  expect(trace.samples.length).toBeGreaterThan(0)
+  expect(
+    bad,
+    JSON.stringify({ bad: bad.slice(0, 8), first: trace.samples.slice(0, 8), last: trace.samples.slice(-4) }, null, 2),
+  ).toEqual([])
+})
+
+async function openReview(page: Page) {
+  await page.setViewportSize({ width: 960, height: 900 })
+  await page.addInitScript(() => {
+    localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: true } }))
+  })
+  await mockOpenCodeServer(page, {
+    directory,
+    project: {
+      id: "proj_review_image_flash_regression",
+      worktree: directory,
+      vcs: "git",
+      name: "review-image-flash-regression",
+      time: { created: 1700000000000, updated: 1700000000000 },
+      sandboxes: [],
+    },
+    provider: { all: [], connected: [], default: {} },
+    sessions: [
+      {
+        id: sessionID,
+        slug: "review-image-flash-regression",
+        projectID: "proj_review_image_flash_regression",
+        directory,
+        title,
+        version: "dev",
+        time: { created: 1700000000000, updated: 1700000000000 },
+      },
+    ],
+    vcsDiff: [
+      {
+        file: "src/example.ts",
+        additions: 1,
+        deletions: 1,
+        status: "modified",
+        patch:
+          "diff --git a/src/example.ts b/src/example.ts\n--- a/src/example.ts\n+++ b/src/example.ts\n@@ -1 +1 @@\n-export const value = 'before'\n+export const value = 'after'\n",
+      },
+      {
+        file: imageFile,
+        patch: "",
+        additions: 1,
+        deletions: 0,
+        status: "added",
+      },
+    ],
+    fileContent: async (path) => {
+      if (path !== imageFile) return undefined
+      await new Promise((resolve) => setTimeout(resolve, 250))
+      return {
+        type: "binary",
+        content: "iVBORw0KGgo=",
+        encoding: "base64",
+        mimeType: "image/png",
+      }
+    },
+    fileList: (path) => {
+      if (!path) {
+        return [
+          { name: "assets", path: "assets", absolute: `${directory}/assets`, type: "directory", ignored: false },
+          { name: "src", path: "src", absolute: `${directory}/src`, type: "directory", ignored: false },
+        ]
+      }
+      if (path === "assets") {
+        return [
+          {
+            name: "preview.png",
+            path: imageFile,
+            absolute: `${directory}/${imageFile}`,
+            type: "file",
+            ignored: false,
+          },
+        ]
+      }
+      if (path === "src") {
+        return [
+          {
+            name: "example.ts",
+            path: "src/example.ts",
+            absolute: `${directory}/src/example.ts`,
+            type: "file",
+            ignored: false,
+          },
+        ]
+      }
+      return []
+    },
+    pageMessages: () => ({
+      items: [
+        {
+          info: {
+            id: "msg_review_image_flash_regression",
+            sessionID,
+            role: "user",
+            time: { created: 1700000000000 },
+            summary: { diffs: [] },
+            agent: "build",
+            model: { providerID: "opencode", modelID: "test" },
+          },
+          parts: [
+            {
+              id: "prt_review_image_flash_regression",
+              sessionID,
+              messageID: "msg_review_image_flash_regression",
+              type: "text",
+              text: "Review this change.",
+            },
+          ],
+        },
+      ],
+    }),
+  })
+
+  await page.goto(`/${base64Encode(directory)}/session/${sessionID}`)
+  await expectSessionTitle(page, title)
+  await page.getByRole("button", { name: "Toggle review" }).click()
+  await expectAppVisible(page.locator('#review-panel [data-component="session-review-v2"]'))
+  await expectAppVisible(page.getByRole("button", { name: /preview\.png/ }))
+}
+
+async function installReviewFlashProbe(page: Page) {
+  await page.evaluate(() => {
+    const samples: Array<{
+      observedAtMs: number
+      blank: boolean
+      blackCenter: boolean
+      text: string
+      background: string
+    }> = []
+    const startedAt = performance.now()
+    const sample = () => {
+      const panel = document.querySelector<HTMLElement>('#review-panel [data-component="session-review-v2"]')
+      const rect = panel?.getBoundingClientRect()
+      const center = rect
+        ? document.elementFromPoint(rect.left + rect.width / 2, rect.top + rect.height / 2)
+        : undefined
+      const background = center instanceof Element ? getComputedStyle(center).backgroundColor : ""
+      samples.push({
+        observedAtMs: performance.now() - startedAt,
+        blank: !panel || panel.textContent?.trim().length === 0,
+        blackCenter: background === "rgb(0, 0, 0)",
+        text: panel?.textContent?.trim().slice(0, 80) ?? "",
+        background,
+      })
+      if (performance.now() - startedAt < 500) requestAnimationFrame(sample)
+    }
+    document.addEventListener(
+      "click",
+      (event) => {
+        const target = event.target instanceof Element ? event.target : undefined
+        if (!target?.closest('[data-slot="file-tree-v2-row"]')) return
+        requestAnimationFrame(sample)
+      },
+      { capture: true, once: true },
+    )
+    ;(window as Window & { __reviewImageFlash?: { samples: typeof samples; startedAt: number } }).__reviewImageFlash = {
+      samples,
+      startedAt,
+    }
+  })
+}
+
+async function waitForReviewFlashProbe(page: Page, durationMs: number) {
+  await page.waitForFunction((durationMs) => {
+    const state = (window as Window & { __reviewImageFlash?: { samples: unknown[]; startedAt: number } })
+      .__reviewImageFlash
+    return !!state && state.samples.length > 0 && performance.now() - state.startedAt >= durationMs
+  }, durationMs)
+}
+
+async function collectReviewFlashProbe(page: Page) {
+  return page.evaluate(() => {
+    return (window as Window & { __reviewImageFlash?: { samples: unknown[]; startedAt: number } }).__reviewImageFlash!
+  }) as Promise<{
+    startedAt: number
+    samples: Array<{ observedAtMs: number; blank: boolean; blackCenter: boolean; text: string; background: string }>
+  }>
+}

packages/app/e2e/regression/review-line-comment.spec.ts

@@ -0,0 +1,169 @@
+import { expect, test, type Page } from "@playwright/test"
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectAppVisible, expectSessionTitle } from "../utils/waits"
+
+const directory = "C:/OpenCode/ReviewLineCommentRegression"
+const sessionID = "ses_review_line_comment_regression"
+const title = "Review line comment regression"
+
+test.beforeEach(async ({ page }) => {
+  await openReview(page)
+})
+
+test("opens the comment editor when code is clicked", async ({ page }) => {
+  const review = page.locator('[data-component="session-review"]')
+  const line = review.getByText("export const value = 'after'", { exact: true })
+  await expectAppVisible(line)
+  await line.click()
+
+  await expect(review.getByRole("textbox")).toBeVisible()
+  await expect(review.locator('[data-slot="line-comment-editor-label"]')).toHaveText("Commenting on line 2")
+})
+
+test("opens the comment editor when a line number is clicked", async ({ page }) => {
+  const review = page.locator('[data-component="session-review"]')
+  const lineNumber = review.locator('[data-column-number="1"]').last()
+  await expectAppVisible(lineNumber)
+  await lineNumber.click()
+
+  await expect(review.getByRole("textbox")).toBeVisible()
+  await expect(review.locator('[data-slot="line-comment-editor-label"]')).toHaveText("Commenting on line 1")
+})
+
+test("opens the comment editor for a line number range", async ({ page }) => {
+  const review = page.locator('[data-component="session-review"]')
+  const start = review.locator('[data-column-number="1"]').last()
+  const end = review.locator('[data-column-number="3"]').last()
+  await expectAppVisible(start)
+  await expectAppVisible(end)
+
+  await start.dragTo(end)
+
+  await expect(review.getByRole("textbox")).toBeVisible()
+  await expect(review.locator('[data-slot="line-comment-editor-label"]')).toHaveText("Commenting on lines 1-3")
+})
+
+test("shows a comment button when a line number is hovered", async ({ page }) => {
+  const review = page.locator('[data-component="session-review"]')
+  const lineNumber = review.locator('[data-column-number="1"]').last()
+  await expectAppVisible(lineNumber)
+
+  const comment = review.getByRole("button", { name: "Comment", exact: true })
+  await expect(async () => {
+    await lineNumber.hover()
+    await expect(lineNumber).toHaveAttribute("data-hovered", "")
+    await expect(comment).toHaveCount(1)
+    await expect(comment).toHaveCSS("pointer-events", "auto")
+    await comment.focus()
+    await expect(comment).toBeFocused()
+  }).toPass({ timeout: 10_000 })
+  await comment.press("Enter")
+  await expect(review.getByRole("textbox")).toBeVisible()
+  await expect(review.locator('[data-slot="line-comment-editor-label"]')).toHaveText("Commenting on line 1")
+})
+
+test("stages a submitted line comment in the prompt context", async ({ page }) => {
+  page.on("request", (request) => {
+    expect.soft(request.method(), `unexpected ${request.method()} ${new URL(request.url()).pathname}`).toBe("GET")
+  })
+
+  const review = page.locator('[data-component="session-review"]')
+  await review.getByText("export const value = 'after'", { exact: true }).click()
+  const textbox = review.getByRole("textbox")
+  await expect(textbox).toBeVisible()
+  await expect(review.locator('[data-slot="line-comment-editor-label"]')).toHaveText("Commenting on line 2")
+  await textbox.fill("Use the existing value instead")
+  const submit = review.locator('[data-slot="line-comment-action"][data-variant="primary"]')
+  await expect(submit).toBeEnabled()
+  await submit.click()
+
+  await expect(review.getByText("Use the existing value instead", { exact: true })).toBeVisible()
+  await page.getByRole("tab", { name: "Session" }).click()
+  const context = page.getByText("Use the existing value instead", { exact: true }).last()
+  await expect(context).toBeVisible()
+  await expect(context.locator("..")).toContainText("review.ts:2")
+})
+
+async function openReview(page: Page) {
+  await page.setViewportSize({ width: 700, height: 900 })
+  await mockOpenCodeServer(page, {
+    protocol: "v2",
+    directory,
+    project: {
+      id: "proj_review_line_comment_regression",
+      worktree: directory,
+      vcs: "git",
+      name: "review-line-comment-regression",
+      time: { created: 1700000000000, updated: 1700000000000 },
+      sandboxes: [],
+    },
+    provider: { all: [], connected: [], default: {} },
+    sessions: [
+      {
+        id: sessionID,
+        slug: "review-line-comment-regression",
+        projectID: "proj_review_line_comment_regression",
+        directory,
+        title,
+        version: "dev",
+        time: { created: 1700000000000, updated: 1700000000000 },
+      },
+    ],
+    vcsDiff: [
+      {
+        file: "src/review.ts",
+        additions: 1,
+        deletions: 1,
+        status: "modified",
+        patch:
+          "diff --git a/src/review.ts b/src/review.ts\n--- a/src/review.ts\n+++ b/src/review.ts\n@@ -1,3 +1,3 @@\n export const first = 1\n-export const value = 'before'\n+export const value = 'after'\n export const last = 3\n",
+      },
+    ],
+    pageMessages: () => ({
+      items: [
+        {
+          info: {
+            id: "msg_review_line_comment_regression",
+            sessionID,
+            role: "user",
+            time: { created: 1700000000000 },
+            summary: { diffs: [] },
+            agent: "build",
+            model: { providerID: "opencode", modelID: "test" },
+          },
+          parts: [
+            {
+              id: "prt_review_line_comment_regression",
+              sessionID,
+              messageID: "msg_review_line_comment_regression",
+              type: "text",
+              text: "Review this change.",
+            },
+          ],
+        },
+      ],
+    }),
+  })
+
+  await page.goto(`/${base64Encode(directory)}/session/${sessionID}`)
+  await expectSessionTitle(page, title)
+  const changes = page.getByRole("tab", { name: "Changes" })
+  const diffResponse = page.waitForResponse(
+    (response) =>
+      response.request().method() === "GET" && response.ok() && new URL(response.url()).pathname === "/api/vcs/diff",
+  )
+  await changes.click()
+  expect((await (await diffResponse).json()).data).toHaveLength(1)
+  await expect(page.getByRole("tab", { selected: true })).toHaveAccessibleName(/Files Changed/)
+
+  const review = page.locator('[data-component="session-review"]')
+  await expectAppVisible(review)
+  const file = review.locator('[data-file="src/review.ts"]')
+  await expectAppVisible(file)
+  const trigger = file.getByRole("button", { expanded: false })
+  await expect(trigger).toHaveCount(1)
+  await trigger.click()
+  await expect(file.getByRole("button", { expanded: true })).toBeVisible()
+  await expect(file.getByText("export const value = 'after'", { exact: true })).toBeVisible()
+}

packages/app/e2e/regression/review-open-file.spec.ts

@@ -0,0 +1,163 @@
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { expect, test } from "@playwright/test"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectSessionTitle } from "../utils/waits"
+
+const directory = "C:/OpenCode/ReviewOpenFile"
+const projectID = "proj_review_open_file"
+const sessionID = "ses_review_open_file"
+const title = "Review open file"
+const server = `http://${process.env.PLAYWRIGHT_SERVER_HOST ?? "127.0.0.1"}:${process.env.PLAYWRIGHT_SERVER_PORT ?? "4096"}`
+
+test.use({ viewport: { width: 1440, height: 900 } })
+
+test("opens and searches project files inline", async ({ page }) => {
+  const searches: { query: string; dirs?: string; limit?: number }[] = []
+  await mockOpenCodeServer(page, {
+    directory,
+    project: {
+      id: projectID,
+      worktree: directory,
+      vcs: "git",
+      name: "open-file-project",
+      time: { created: 1700000000000, updated: 1700000000000 },
+      sandboxes: [],
+    },
+    provider: {
+      all: [
+        {
+          id: "opencode",
+          name: "OpenCode",
+          models: { test: { id: "test", name: "Test", limit: { context: 200_000 } } },
+        },
+      ],
+      connected: ["opencode"],
+      default: { providerID: "opencode", modelID: "test" },
+    },
+    sessions: [
+      {
+        id: sessionID,
+        slug: sessionID,
+        projectID,
+        directory,
+        title,
+        version: "dev",
+        time: { created: 1700000000000, updated: 1700000000000 },
+      },
+    ],
+    vcsDiff: [fileDiff("src/changed.ts")],
+    fileList: (path) => {
+      if (path) return []
+      return [
+        fileNode("README.md"),
+        { name: "src", path: "src", absolute: `${directory}/src`, type: "directory", ignored: false },
+      ]
+    },
+    fileContent: (path) => ({ type: "text", content: `contents:${path}` }),
+    findFiles: (input) => {
+      searches.push(input)
+      return input.query === "nested" ? ["src/nested.ts"] : []
+    },
+    pageMessages: () => ({ items: [] }),
+  })
+  await page.addInitScript(
+    ({ directory, server, sessionID }) => {
+      localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: true } }))
+      localStorage.setItem(
+        "opencode.global.dat:server",
+        JSON.stringify({
+          projects: { local: [{ worktree: directory, expanded: true }] },
+          lastProject: { local: directory },
+        }),
+      )
+      localStorage.setItem(
+        "opencode.global.dat:layout",
+        JSON.stringify({ review: { diffStyle: "split", panelOpened: true } }),
+      )
+      localStorage.setItem(
+        "opencode.global.dat:review-panel-v2",
+        JSON.stringify({ sidebarOpened: false, sidebarWidth: 240, expandMode: "collapse" }),
+      )
+      localStorage.setItem(
+        "opencode.window.browser.dat:tabs",
+        JSON.stringify([{ type: "session", server, sessionId: sessionID }]),
+      )
+    },
+    { directory, server, sessionID },
+  )
+
+  await page.goto(`/server/${base64Encode(server)}/session/${sessionID}`)
+  await expectSessionTitle(page, title)
+
+  const panel = page.locator("#review-panel")
+  const sidebar = panel.locator('[data-slot="session-review-v2-sidebar"]')
+  const sidebarToggle = panel.getByRole("button", { name: "Toggle file tree" })
+  const contextButton = page.getByRole("button", { name: "View context usage" })
+  await contextButton.click()
+  await expect(panel.getByRole("tab", { name: "Context" })).toHaveAttribute("data-selected", "")
+  await panel.getByRole("button", { name: "Open file" }).click()
+  await expect(panel.getByRole("tab", { name: "Open file" })).toHaveAttribute("data-selected", "")
+  await expect(sidebarToggle).toBeDisabled()
+  await expect(sidebar).toBeVisible()
+  await contextButton.click()
+  await expect(panel.getByRole("tab", { name: "Context" })).toHaveAttribute("data-selected", "")
+  await expect(sidebar).toBeHidden()
+  await panel.getByRole("button", { name: "Open file" }).click()
+  const filter = panel.getByRole("combobox", { name: "Filter files" })
+  await expect(filter).toBeFocused()
+  await expect(panel.getByRole("tab", { name: "Open file" })).toHaveAttribute("data-selected", "")
+  await expect(panel.getByText("open-file-project", { exact: true })).toBeVisible()
+
+  await panel.getByRole("button", { name: "README.md" }).click()
+  await expect(panel.getByRole("tab", { name: "README.md" })).toHaveAttribute("data-selected", "")
+  await expect(sidebarToggle).toBeEnabled()
+  await expect(panel.getByText("contents:README.md", { exact: true })).toBeVisible()
+  await expect(sidebar).toHaveCount(0)
+
+  await panel.getByRole("button", { name: "Open file" }).click()
+  await expect(panel.getByRole("tab", { name: "README.md" })).toHaveCount(0)
+  await expect(sidebar).toBeVisible()
+  await filter.fill("nested")
+  const result = panel.getByRole("option", { name: /nested\.ts/ })
+  await expect(result).toBeVisible()
+  const resultID = await result.getAttribute("id")
+  expect(resultID).toBeTruthy()
+  await expect(filter).toHaveAttribute("aria-activedescendant", resultID!)
+  await filter.press("Enter")
+  await expect(panel.getByRole("tab", { name: "nested.ts" })).toHaveAttribute("data-selected", "")
+  await expect(sidebarToggle).toBeEnabled()
+  await expect(panel.getByText("contents:src/nested.ts", { exact: true })).toBeVisible()
+  expect(searches).toContainEqual({ query: "nested", dirs: "false", limit: 200 })
+
+  await panel.getByRole("button", { name: "Open file" }).click()
+  await expect(panel.getByRole("tab", { name: "nested.ts" })).toHaveCount(1)
+  await expect(panel.getByRole("tab", { name: "Open file" })).toHaveAttribute("data-selected", "")
+  await expect(sidebarToggle).toBeDisabled()
+  await panel.locator("#session-side-panel-review-tab").click()
+  await expect(sidebarToggle).toBeEnabled()
+  await panel.getByRole("tab", { name: "Open file" }).click()
+  await page.keyboard.press("Control+w")
+  await expect(panel.getByRole("tab", { name: "Open file" })).toHaveCount(0)
+  await expect(panel.getByRole("tab", { name: "nested.ts" })).toHaveAttribute("data-selected", "")
+})
+
+function fileNode(path: string) {
+  return {
+    name: path,
+    path,
+    absolute: `${directory}/${path}`,
+    type: "file",
+    ignored: false,
+  }
+}
+
+function fileDiff(file: string) {
+  return {
+    file,
+    before: "before\n",
+    after: "after\n",
+    additions: 1,
+    deletions: 1,
+    status: "modified",
+  }
+}

packages/app/e2e/regression/review-state-persistence.spec.ts

@@ -0,0 +1,153 @@
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { expect, test, type Page } from "@playwright/test"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectSessionTitle } from "../utils/waits"
+
+const directory = "C:/OpenCode/ReviewStatePersistence"
+const projectID = "proj_review_state_persistence"
+const sessionA = "ses_review_state_a"
+const sessionB = "ses_review_state_b"
+const titleA = "Alpha review state"
+const titleB = "Beta review state"
+const server = `http://${process.env.PLAYWRIGHT_SERVER_HOST ?? "127.0.0.1"}:${process.env.PLAYWRIGHT_SERVER_PORT ?? "4096"}`
+
+test.use({ viewport: { width: 1440, height: 900 } })
+
+test("restores review mode and selected file per session", async ({ page }) => {
+  await setup(page)
+  await page.goto(sessionHref(sessionA))
+  await expectSessionTitle(page, titleA)
+  await page.getByRole("button", { name: "Toggle review" }).click()
+
+  await selectMode(page, "Git changes", "Branch changes")
+  await selectFile(page, "beta.ts")
+
+  await switchSession(page, titleB)
+  await expect(page.getByRole("button", { name: "Git changes" })).toBeVisible()
+  await selectFile(page, "gamma.ts")
+
+  await switchSession(page, titleA)
+  await expect(page.getByRole("button", { name: "Branch changes" })).toBeVisible()
+  await expectSelectedFile(page, "beta.ts")
+  await selectMode(page, "Branch changes", "Git changes")
+  await expectSelectedFile(page, "alpha.ts")
+  await selectMode(page, "Git changes", "Branch changes")
+  await expectSelectedFile(page, "beta.ts")
+
+  await page.reload()
+  await expectSessionTitle(page, titleA)
+  await expect(page.getByRole("button", { name: "Branch changes" })).toBeVisible()
+  await expectSelectedFile(page, "beta.ts")
+
+  await switchSession(page, titleB)
+  await expect(page.getByRole("button", { name: "Git changes" })).toBeVisible()
+  await expectSelectedFile(page, "gamma.ts")
+})
+
+async function selectMode(page: Page, current: string, next: string) {
+  await page.getByRole("button", { name: current }).click()
+  await page.getByRole("option", { name: next }).dispatchEvent("click")
+}
+
+async function selectFile(page: Page, file: string) {
+  await page.getByRole("button", { name: file }).click()
+  await expectSelectedFile(page, file)
+}
+
+async function expectSelectedFile(page: Page, file: string) {
+  await expect(page.locator('[data-slot="session-review-v2-file-name"]')).toHaveText(file)
+}
+
+async function switchSession(page: Page, title: string) {
+  await page.locator("[data-titlebar-tab-slot]", { hasText: title }).click()
+  await expectSessionTitle(page, title)
+}
+
+async function setup(page: Page) {
+  await mockOpenCodeServer(page, {
+    protocol: "v1",
+    directory,
+    project: {
+      id: projectID,
+      worktree: directory,
+      vcs: "git",
+      name: "review-state-persistence",
+      time: { created: 1700000000000, updated: 1700000000000 },
+      sandboxes: [],
+    },
+    provider: {
+      all: [
+        {
+          id: "opencode",
+          name: "OpenCode",
+          models: { test: { id: "test", name: "Test", limit: { context: 200_000 } } },
+        },
+      ],
+      connected: ["opencode"],
+      default: { providerID: "opencode", modelID: "test" },
+    },
+    sessions: [session(sessionA, titleA, 1700000000000), session(sessionB, titleB, 1700000001000)],
+    pageMessages: () => ({ items: [] }),
+  })
+  await page.route(/\/vcs(?:\?.*)?$/, (route) =>
+    route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      body: JSON.stringify({ branch: "feature", default_branch: "dev" }),
+    }),
+  )
+  await page.route("**/vcs/diff**", (route) =>
+    route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      body: JSON.stringify(
+        new URL(route.request().url()).searchParams.get("mode") === "branch"
+          ? [diff("src/alpha.ts"), diff("src/beta.ts")]
+          : [diff("src/alpha.ts"), diff("src/gamma.ts")],
+      ),
+    }),
+  )
+  await page.addInitScript(
+    ({ directory, server, sessions }) => {
+      localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: true } }))
+      localStorage.setItem(
+        "opencode.global.dat:server",
+        JSON.stringify({
+          projects: { local: [{ worktree: directory, expanded: true }] },
+          lastProject: { local: directory },
+        }),
+      )
+      localStorage.setItem(
+        "opencode.window.browser.dat:tabs",
+        JSON.stringify(sessions.map((sessionId: string) => ({ type: "session", server, sessionId }))),
+      )
+    },
+    { directory, server, sessions: [sessionA, sessionB] },
+  )
+}
+
+function session(id: string, title: string, created: number) {
+  return {
+    id,
+    slug: id,
+    projectID,
+    directory,
+    title,
+    version: "dev",
+    time: { created, updated: created },
+  }
+}
+
+function diff(file: string) {
+  return {
+    file,
+    additions: 1,
+    deletions: 1,
+    status: "modified",
+    patch: `diff --git a/${file} b/${file}\n--- a/${file}\n+++ b/${file}\n@@ -1 +1 @@\n-export const value = 'before'\n+export const value = 'after'\n`,
+  }
+}
+
+function sessionHref(sessionID: string) {
+  return `/server/${base64Encode(server)}/session/${sessionID}`
+}

packages/app/e2e/regression/review-tab-switch.spec.ts

@@ -0,0 +1,147 @@
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { expect, test, type Page } from "@playwright/test"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectAppVisible, expectSessionTitle } from "../utils/waits"
+
+const directory = "C:/OpenCode/ReviewTabSwitch"
+const projectID = "proj_review_tab_switch"
+const sessionA = "ses_review_tab_a"
+const sessionB = "ses_review_tab_b"
+const titleA = "Alpha session"
+const titleB = "Beta session"
+const server = `http://${process.env.PLAYWRIGHT_SERVER_HOST ?? "127.0.0.1"}:${process.env.PLAYWRIGHT_SERVER_PORT ?? "4096"}`
+const diffs = Array.from({ length: 2_740 }, (_, index) =>
+  fileDiff(`src/generated-${String(index).padStart(4, "0")}.ts`),
+)
+// Marks the review pane DOM node so a remount (fresh node) is detectable.
+const PROBE = "original"
+
+test.use({ viewport: { width: 1440, height: 900 } })
+
+// The v2 review pane's diff data is workspace-scoped: switching between session
+// tabs in the same workspace must update its parameters reactively instead of
+// tearing the pane down and remounting it (which flickers).
+test("keeps the v2 review pane mounted when switching session tabs in a workspace", async ({ page }) => {
+  await setup(page)
+
+  await page.goto(sessionHref(sessionA))
+  await expectSessionTitle(page, titleA)
+
+  await page.getByRole("button", { name: "Toggle review" }).click()
+  const reviewTab = page.locator("#session-side-panel-review-tab")
+  const reviewTabPanel = page.locator("#session-side-panel-review-tabpanel")
+  await expect(reviewTab).toHaveAttribute("aria-controls", "session-side-panel-review-tabpanel")
+  await expect(reviewTabPanel).toHaveAttribute("id", "session-side-panel-review-tabpanel")
+  const review = page.locator('#review-panel [data-component="session-review-v2"]')
+  await expectAppVisible(review)
+  await expectAppVisible(page.getByRole("button", { name: "generated-0000.ts" }))
+  await writeProbe(page)
+
+  await switchTab(page, titleB)
+  await expectSessionTitle(page, titleB)
+  await expectAppVisible(review)
+  await expectAppVisible(page.getByRole("button", { name: "generated-0000.ts" }))
+  expect(await readProbe(page)).toBe(PROBE)
+
+  await switchTab(page, titleA)
+  await expectSessionTitle(page, titleA)
+  await expectAppVisible(review)
+  await expectAppVisible(page.getByRole("button", { name: "generated-0000.ts" }))
+  expect(await readProbe(page)).toBe(PROBE)
+
+  const viewport = page.locator('#review-panel [data-slot="session-review-v2-sidebar-tree"] .scroll-view__viewport')
+  await viewport.hover()
+  await page.mouse.wheel(0, 100_000)
+  await expect
+    .poll(() => viewport.evaluate((element) => element.scrollHeight - element.clientHeight - element.scrollTop))
+    .toBeLessThanOrEqual(1)
+  await expect(page.getByRole("button", { name: "generated-2739.ts" })).toBeVisible()
+})
+
+type Probed = HTMLElement & { __e2eProbe?: string }
+
+async function switchTab(page: Page, title: string) {
+  await page.locator("[data-titlebar-tab-slot]", { hasText: title }).click()
+}
+
+async function writeProbe(page: Page) {
+  await page.locator('#review-panel [data-component="session-review-v2"]').evaluate((el, probe) => {
+    ;(el as Probed).__e2eProbe = probe
+  }, PROBE)
+}
+
+async function readProbe(page: Page) {
+  return page.locator('#review-panel [data-component="session-review-v2"]').evaluate((el) => (el as Probed).__e2eProbe)
+}
+
+async function setup(page: Page) {
+  await mockOpenCodeServer(page, {
+    directory,
+    project: {
+      id: projectID,
+      worktree: directory,
+      vcs: "git",
+      name: "review-tab-switch",
+      time: { created: 1700000000000, updated: 1700000000000 },
+      sandboxes: [],
+    },
+    provider: {
+      all: [
+        {
+          id: "opencode",
+          name: "OpenCode",
+          models: { test: { id: "test", name: "Test", limit: { context: 200_000 } } },
+        },
+      ],
+      connected: ["opencode"],
+      default: { providerID: "opencode", modelID: "test" },
+    },
+    sessions: [session(sessionA, titleA, 1700000000000), session(sessionB, titleB, 1700000001000)],
+    vcsDiff: diffs,
+    pageMessages: () => ({ items: [] }),
+  })
+
+  await page.addInitScript(
+    ({ directory, server, sessions }) => {
+      localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: true } }))
+      localStorage.setItem(
+        "opencode.global.dat:server",
+        JSON.stringify({
+          projects: { local: [{ worktree: directory, expanded: true }] },
+          lastProject: { local: directory },
+        }),
+      )
+      localStorage.setItem(
+        "opencode.window.browser.dat:tabs",
+        JSON.stringify(sessions.map((sessionId: string) => ({ type: "session", server, sessionId }))),
+      )
+    },
+    { directory, server, sessions: [sessionA, sessionB] },
+  )
+}
+
+function session(id: string, title: string, created: number) {
+  return {
+    id,
+    slug: id,
+    projectID,
+    directory,
+    title,
+    version: "dev",
+    time: { created, updated: created },
+  }
+}
+
+function sessionHref(sessionID: string) {
+  return `/server/${base64Encode(server)}/session/${sessionID}`
+}
+
+function fileDiff(file: string) {
+  return {
+    file,
+    additions: 1,
+    deletions: 1,
+    status: "modified",
+    patch: `diff --git a/${file} b/${file}\n--- a/${file}\n+++ b/${file}\n@@ -1 +1 @@\n-export const value = 'before'\n+export const value = 'after'\n`,
+  }
+}

packages/app/e2e/regression/review-terminal-stacked.spec.ts

@@ -0,0 +1,306 @@
+import { expect, test, type Page } from "@playwright/test"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectSessionTitle } from "../utils/waits"
+
+const directory = "C:/OpenCode/ReviewTerminalStacked"
+const projectID = "proj_review_terminal_stacked"
+const sessionID = "ses_review_terminal_stacked"
+const title = "Review terminal stacked"
+const branchDiffs = [
+  fileDiff(".github/actions/setup-bun/action.yml", 7),
+  ...Array.from({ length: 2_739 }, (_, index) =>
+    fileDiff(
+      `src/branch/d${String(Math.floor(index / 100)).padStart(5, "0")}/generated-${String(index).padStart(4, "0")}.ts`,
+      100,
+      false,
+    ),
+  ),
+]
+
+test("keeps the review tree and terminal sized when both panels are open", async ({ page }) => {
+  test.setTimeout(120_000)
+  const events: Array<{ directory: string; payload: Record<string, unknown> }> = []
+  const sessionStatus = { [sessionID]: { type: "idle" as "busy" | "idle" } }
+  let detailVersion = 1
+  let detailFailures = 1
+  await page.setViewportSize({ width: 1400, height: 900 })
+  await mockOpenCodeServer(page, {
+    protocol: "v1",
+    directory,
+    project: {
+      id: projectID,
+      worktree: directory,
+      vcs: "git",
+      name: "review-terminal-stacked",
+      time: { created: 1700000000000, updated: 1700000000000 },
+      sandboxes: [],
+    },
+    provider: {
+      all: [
+        {
+          id: "opencode",
+          name: "OpenCode",
+          models: { test: { id: "test", name: "Test", limit: { context: 200_000 } } },
+        },
+      ],
+      connected: ["opencode"],
+      default: { providerID: "opencode", modelID: "test" },
+    },
+    sessions: [
+      {
+        id: sessionID,
+        slug: "review-terminal-stacked",
+        projectID,
+        directory,
+        title,
+        version: "dev",
+        time: { created: 1700000000000, updated: 1700000000000 },
+      },
+    ],
+    sessionStatus: () => sessionStatus,
+    pageMessages: () => ({ items: [] }),
+    events: () => events.splice(0, 1),
+    eventRetry: 16,
+  })
+  await page.route(/\/vcs(?:\?.*)?$/, (route) =>
+    route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      body: JSON.stringify({
+        branch: "review-pane-performance",
+        default_branch: "dev",
+      }),
+    }),
+  )
+  await page.route("**/vcs/diff**", (route) => {
+    const url = new URL(route.request().url())
+    const scope = url.searchParams.get("directory")?.replaceAll("\\", "/")
+    const detail = scope?.endsWith("/src/branch/d00027")
+    if (detail && detailFailures-- > 0) return route.fulfill({ status: 500, body: "retry detail" })
+    return route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      body: JSON.stringify(
+        url.searchParams.get("mode") === "branch"
+          ? detail
+            ? branchDiffs
+                .filter((diff) => diff.file.startsWith("src/branch/d00027/"))
+                .map((diff) => fileDiff(diff.file, diff.additions, true, detailVersion))
+            : branchDiffs
+          : Array.from({ length: 7 }, (_, index) => fileDiff(`src/git-${index}.ts`, 1)),
+      ),
+    })
+  })
+  await page.route("**/pty*", (route) =>
+    route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      body: JSON.stringify({
+        location: { directory, project: { id: projectID, directory } },
+        data: {
+          id: "pty_review_terminal",
+          title: "Terminal 1",
+          command: "cmd.exe",
+          args: [],
+          cwd: directory,
+          status: "running",
+          pid: 1,
+        },
+      }),
+    }),
+  )
+  await page.route("**/pty/pty_review_terminal*", (route) =>
+    route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      body: JSON.stringify({
+        location: { directory, project: { id: projectID, directory } },
+        data: {
+          id: "pty_review_terminal",
+          title: "Terminal 1",
+          command: "cmd.exe",
+          args: [],
+          cwd: directory,
+          status: "running",
+          pid: 1,
+        },
+      }),
+    }),
+  )
+  await page.route("**/pty/pty_review_terminal/connect-token*", (route) =>
+    route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      body: JSON.stringify({
+        location: { directory, project: { id: projectID, directory } },
+        data: { ticket: "e2e-ticket", expires_in: 60 },
+      }),
+    }),
+  )
+  await page.routeWebSocket("**/pty/pty_review_terminal/connect", () => undefined)
+  await page.addInitScript(() => {
+    localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: true } }))
+    localStorage.setItem(
+      "opencode.global.dat:layout",
+      JSON.stringify({ review: { diffStyle: "split", panelOpened: true } }),
+    )
+  })
+
+  await page.goto(`/${base64Encode(directory)}/session/${sessionID}`)
+  await expectSessionTitle(page, title)
+  await expect(page.locator("#review-panel")).toBeVisible()
+  await expectTree(page, 8, "git-0.ts")
+
+  await selectMode(page, "Git changes", "Branch changes")
+  await expect(page.locator("#session-side-panel-review-tab")).toHaveText("Files Changed 2740")
+  await page.keyboard.press("Control+Backquote")
+  await expect(page.locator("#terminal-panel")).toBeVisible()
+  await expectTree(page, 2_773, "action.yml")
+  await expectStackGeometry(page)
+
+  const treeViewport = page.locator('#review-panel [data-slot="session-review-v2-sidebar-tree"] .scroll-view__viewport')
+  await treeViewport.hover()
+  await page.mouse.wheel(0, 100_000)
+  await expect
+    .poll(() => treeViewport.evaluate((element) => element.scrollHeight - element.clientHeight - element.scrollTop))
+    .toBeLessThanOrEqual(1)
+  const lastFile = page.getByRole("button", { name: "generated-2738.ts" })
+  await expect(lastFile).toBeVisible()
+  const bottomGap = await lastFile.evaluate((element) => {
+    const viewport = element.closest<HTMLElement>(".scroll-view__viewport")!.getBoundingClientRect()
+    return viewport.bottom - element.getBoundingClientRect().bottom
+  })
+  expect(bottomGap).toBeGreaterThanOrEqual(0)
+  expect(bottomGap).toBeLessThanOrEqual(16)
+  const lazyDiff = page.waitForRequest((request) => {
+    const url = new URL(request.url())
+    return (
+      url.pathname === "/vcs/diff" &&
+      url.searchParams.get("directory")?.replaceAll("\\", "/").endsWith("/src/branch/d00027") === true
+    )
+  })
+  await lastFile.click()
+  await lazyDiff
+  const preview = page.locator('[data-slot="session-review-v2-diff-scroll"]')
+  await expect(preview).toContainText("after-1")
+  detailVersion = 2
+  sessionStatus[sessionID] = { type: "busy" }
+  events.push(statusEvent("busy"))
+  await expect(page.getByRole("button", { name: "Stop" })).toBeVisible()
+  const refreshedDiff = page.waitForRequest((request) => {
+    const url = new URL(request.url())
+    return (
+      url.pathname === "/vcs/diff" &&
+      url.searchParams.get("directory")?.replaceAll("\\", "/").endsWith("/src/branch/d00027") === true
+    )
+  })
+  sessionStatus[sessionID] = { type: "idle" }
+  events.push(statusEvent("idle"))
+  await refreshedDiff
+  await expect(preview).toContainText("after-2")
+  await selectMode(page, "Branch changes", "Git changes")
+  await expectTree(page, 8, "git-0.ts")
+  await page.getByRole("button", { name: "git-0.ts" }).click()
+  await selectMode(page, "Git changes", "Branch changes")
+  await expectTree(page, 2_773, "action.yml")
+
+  const filter = page.getByRole("searchbox", { name: "Filter files" })
+  await filter.fill("generated-2738")
+  await expectTree(page, 1, "generated-2738.ts")
+  await filter.fill("")
+  await expectTree(page, 2_773, "action.yml")
+
+  await page.getByRole("button", { name: "Toggle file tree" }).click()
+  await expect(page.locator('[data-slot="session-review-v2-sidebar"]')).toHaveCount(0)
+  await expect(page.locator('#review-panel [data-component="file-tree-v2"]')).toHaveCount(0)
+  await page.getByRole("button", { name: "Toggle file tree" }).click()
+  await expectTree(page, 2_773, "action.yml")
+
+  await page.keyboard.press("Control+Backquote")
+  await expect(page.locator("#terminal-panel")).toHaveCount(0)
+  await expectTree(page, 2_773, "action.yml")
+  await page.keyboard.press("Control+Backquote")
+  await expect(page.locator("#terminal-panel")).toBeVisible()
+  await expectTree(page, 2_773, "action.yml")
+
+  await page.getByRole("button", { name: "Toggle review" }).click()
+  await expect(page.locator("#review-panel")).toHaveCount(0)
+  await page.getByRole("button", { name: "Toggle review" }).click()
+  await expectTree(page, 2_773, "action.yml")
+  await page.setViewportSize({ width: 1_000, height: 700 })
+  await expectTree(page, 2_773, "action.yml")
+  await expectStackGeometry(page)
+  await page.setViewportSize({ width: 1_000, height: 120 })
+  await page.setViewportSize({ width: 1_400, height: 900 })
+  await expectTree(page, 2_773, "action.yml")
+  await expectStackGeometry(page)
+})
+
+async function selectMode(page: Page, current: string, next: string) {
+  await page.getByRole("button", { name: current }).click()
+  const option = page.getByRole("option", { name: next })
+  await expect(option).toBeVisible()
+  await option.click()
+}
+
+async function expectTree(page: Page, total: number, file: string) {
+  await expectMountedTree(page, total)
+  await expect(page.getByRole("button", { name: file })).toBeVisible()
+}
+
+async function expectMountedTree(page: Page, total: number) {
+  const tree = page.locator('#review-panel [data-component="file-tree-v2"]')
+  await expect(tree).toHaveAttribute("data-total-rows", String(total))
+  await expect
+    .poll(() => tree.evaluate((element) => element.querySelectorAll('[data-slot="file-tree-v2-row"]').length))
+    .toBeGreaterThan(0)
+  const state = await tree.evaluate((element) => ({
+    root: element.getBoundingClientRect().height,
+    viewport: element.closest<HTMLElement>(".scroll-view__viewport")!.getBoundingClientRect().height,
+    rows: element.querySelectorAll('[data-slot="file-tree-v2-row"]').length,
+  }))
+  expect(state.viewport).toBeGreaterThan(0)
+  expect(state.root).toBeGreaterThan(0)
+  expect(state.rows).toBeGreaterThan(0)
+  expect(state.rows).toBeLessThanOrEqual(60)
+}
+
+async function expectStackGeometry(page: Page) {
+  const geometry = await page.evaluate(() => {
+    const review = document.querySelector<HTMLElement>("#review-panel")!
+    const terminal = document.querySelector<HTMLElement>("#terminal-panel")!
+    const reviewParent = review.parentElement!.getBoundingClientRect()
+    const terminalParent = terminal.parentElement!.getBoundingClientRect()
+    return {
+      review: review.getBoundingClientRect().height,
+      reviewParent: reviewParent.height,
+      terminal: terminal.getBoundingClientRect().height,
+      terminalParent: terminalParent.height,
+    }
+  })
+  expect(Math.abs(geometry.review - geometry.reviewParent)).toBeLessThanOrEqual(1)
+  expect(Math.abs(geometry.terminal - geometry.terminalParent)).toBeLessThanOrEqual(1)
+}
+
+function base64Encode(value: string) {
+  return Buffer.from(value, "utf8").toString("base64").replace(/\+/g, "-").replace(/\//g, "_").replace(/=/g, "")
+}
+
+function statusEvent(type: "busy" | "idle") {
+  return {
+    directory,
+    payload: { type: "session.status", properties: { sessionID, status: { type } } },
+  }
+}
+
+function fileDiff(file: string, additions: number, loaded = true, version = 1) {
+  return {
+    file,
+    additions,
+    deletions: 0,
+    status: "modified",
+    patch: loaded
+      ? `diff --git a/${file} b/${file}\n--- a/${file}\n+++ b/${file}\n@@ -1 +1 @@\n-export const value = 'before'\n+export const value = 'after-${version}'\n`
+      : `diff --git a/${file} b/${file}\n--- a/${file}\n+++ b/${file}`,
+  }
+}

packages/app/e2e/regression/session-list-path-loading.spec.ts

@@ -0,0 +1,41 @@
+import { test } from "@playwright/test"
+import { fixture, pageMessages } from "../smoke/session-timeline.fixture"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectAppVisible } from "../utils/waits"
+
+test("shows loaded sessions before the directory path request resolves", async ({ page }) => {
+  await mockOpenCodeServer(page, {
+    sessions: fixture.sessions,
+    provider: fixture.provider,
+    directory: fixture.directory,
+    project: fixture.project,
+    pageMessages,
+  })
+
+  let releasePath!: () => void
+  const pathBlocked = new Promise<void>((resolve) => {
+    releasePath = resolve
+  })
+  await page.route("**/api/path?*", async (route) => {
+    if (!new URL(route.request().url()).searchParams.has("location[directory]")) return route.fallback()
+    await pathBlocked
+    return route.fallback()
+  })
+
+  await page.addInitScript((directory) => {
+    localStorage.setItem(
+      "opencode.global.dat:server",
+      JSON.stringify({
+        projects: { local: [{ worktree: directory, expanded: true }] },
+        lastProject: { local: directory },
+      }),
+    )
+  }, fixture.directory)
+
+  await page.goto("/")
+  try {
+    await expectAppVisible(page.getByText(fixture.expected.sourceTitle).first())
+  } finally {
+    releasePath()
+  }
+})

packages/app/e2e/regression/session-rename.spec.ts

@@ -0,0 +1,141 @@
+import { expect, test } from "@playwright/test"
+import { fixture, pageMessages } from "../smoke/session-timeline.fixture"
+import { mockOpenCodeServer } from "../utils/mock-server"
+
+test.beforeEach(async ({ page }) => {
+  const sessions = fixture.sessions.map((session) => ({ ...session }))
+  await mockOpenCodeServer(page, {
+    protocol: "v1",
+    sessions,
+    provider: fixture.provider,
+    directory: fixture.directory,
+    project: fixture.project,
+    pageMessages,
+  })
+  await page.route(/\/session\/[^/]+(?:\?.*)?$/, async (route) => {
+    if (route.request().method() !== "PATCH") return route.fallback()
+    const id = new URL(route.request().url()).pathname.split("/").at(-1)
+    const session = sessions.find((item) => item.id === id)
+    const payload: unknown = route.request().postDataJSON()
+    if (
+      !session ||
+      !payload ||
+      typeof payload !== "object" ||
+      !("title" in payload) ||
+      typeof payload.title !== "string"
+    )
+      throw new Error("Invalid rename request")
+    session.title = payload.title
+    await route.fulfill({ json: session, headers: { "access-control-allow-origin": "*" } })
+  })
+  await page.addInitScript((directory) => {
+    localStorage.setItem(
+      "opencode.global.dat:server",
+      JSON.stringify({
+        projects: { local: [{ worktree: directory, expanded: true }] },
+        lastProject: { local: directory },
+      }),
+    )
+  }, fixture.directory)
+  await page.goto("/")
+  await page.locator('[data-component="home-session-row"]').filter({ hasText: fixture.expected.targetTitle }).click()
+  await expect(page.getByRole("heading", { name: fixture.expected.targetTitle, exact: true })).toBeVisible()
+})
+
+for (const commit of ["Enter", "blur", "click outside"]) {
+  test(`saves the session heading on ${commit}`, async ({ page }) => {
+    await page.getByRole("heading", { name: fixture.expected.targetTitle, exact: true }).click()
+    const input = page.locator('input[data-slot="session-title-child"]')
+    await expect(input).toBeFocused()
+    await input.fill("Renamed session")
+    if (commit === "Enter") await input.press("Enter")
+    if (commit === "blur") await input.press("Tab")
+    if (commit === "click outside") await page.getByRole("textbox", { name: "Prompt", exact: true }).click()
+    await expect(page.getByRole("heading", { name: "Renamed session", exact: true })).toBeVisible()
+    await expect(page.locator('[data-slot="titlebar-tabs"] a').filter({ hasText: "Renamed session" })).toBeVisible()
+    await page.reload()
+    await expect(page.getByRole("heading", { name: "Renamed session", exact: true })).toBeVisible()
+  })
+}
+
+test("cancels the session heading with Escape", async ({ page }) => {
+  await page.getByRole("heading", { name: fixture.expected.targetTitle, exact: true }).click()
+  const input = page.locator('input[data-slot="session-title-child"]')
+  await input.fill("Discard this title")
+  await input.press("Escape")
+  await expect(page.getByRole("heading", { name: fixture.expected.targetTitle, exact: true })).toBeVisible()
+  await page.reload()
+  await expect(page.getByRole("heading", { name: fixture.expected.targetTitle, exact: true })).toBeVisible()
+})
+
+test("keeps the draft when saving the session heading fails", async ({ page }) => {
+  await page.route(/\/session\/[^/]+(?:\?.*)?$/, (route) => {
+    if (route.request().method() !== "PATCH") return route.fallback()
+    return route.fulfill({ status: 500, headers: { "access-control-allow-origin": "*" } })
+  })
+  await page.getByRole("heading", { name: fixture.expected.targetTitle, exact: true }).click()
+  const input = page.locator('input[data-slot="session-title-child"]')
+  await input.fill("Retry this title")
+  await input.press("Tab")
+  await expect(page.getByText("Request failed", { exact: true })).toBeVisible()
+  await expect(input).toBeEnabled()
+  await expect(input).toHaveValue("Retry this title")
+  await expect(
+    page.locator('[data-slot="titlebar-tabs"] a').filter({ hasText: fixture.expected.targetTitle }),
+  ).toBeVisible()
+})
+
+test("does not save an empty session heading", async ({ page }) => {
+  await page.getByRole("heading", { name: fixture.expected.targetTitle, exact: true }).click()
+  const input = page.locator('input[data-slot="session-title-child"]')
+  await input.fill("   ")
+  await input.press("Tab")
+  await expect(page.getByRole("heading", { name: fixture.expected.targetTitle, exact: true })).toBeVisible()
+  await page.reload()
+  await expect(page.getByRole("heading", { name: fixture.expected.targetTitle, exact: true })).toBeVisible()
+})
+
+test("renames and closes the session tab from its context menu", async ({ page }) => {
+  const tab = page.locator('[data-slot="titlebar-tabs"] a').filter({ hasText: fixture.expected.targetTitle })
+  await tab.click({ button: "right" })
+  await expect(page.getByRole("menuitem", { name: "Rename", exact: true })).toBeVisible()
+  await page.keyboard.press("Escape")
+  await expect(page.getByRole("menuitem", { name: "Rename", exact: true })).toBeHidden()
+  await expect(tab).toBeFocused()
+  await tab.press("Shift+F10")
+  await page.getByRole("menuitem", { name: "Rename", exact: true }).click()
+  const input = page.locator('[data-slot="tab-title"][contenteditable="true"]')
+  await expect(input).toBeFocused()
+  await input.fill("Renamed from tab")
+  await input.press("Enter")
+  await expect(page.getByRole("heading", { name: "Renamed from tab", exact: true })).toBeVisible()
+  await page.reload()
+  await expect(page.getByRole("heading", { name: "Renamed from tab", exact: true })).toBeVisible()
+  const renamed = page.locator('[data-slot="titlebar-tabs"] a').filter({ hasText: "Renamed from tab" })
+  await renamed.click({ button: "right" })
+  await page.getByRole("menuitem", { name: "Close tab", exact: true }).click()
+  await expect(renamed).toBeHidden()
+  await page.getByRole("button", { name: "Home", exact: true }).click()
+  await expect(
+    page.locator('[data-component="home-session-row"]').filter({ hasText: "Renamed from tab" }),
+  ).toBeVisible()
+})
+
+test("renames an inactive tab without switching sessions", async ({ page }) => {
+  await page.getByRole("button", { name: "Home", exact: true }).click()
+  await page.locator('[data-component="home-session-row"]').filter({ hasText: fixture.expected.sourceTitle }).click()
+  await expect(page.getByRole("heading", { name: fixture.expected.sourceTitle, exact: true })).toBeVisible()
+  const tab = page.locator('[data-slot="titlebar-tabs"] a').filter({ hasText: fixture.expected.targetTitle })
+  await tab.click({ button: "right" })
+  await page.getByRole("menuitem", { name: "Rename", exact: true }).click()
+  const input = page.locator('[data-slot="tab-title"][contenteditable="true"]')
+  await expect(input).toBeFocused()
+  await input.fill("Inactive tab renamed")
+  await input.press("Tab")
+  await expect(page.getByRole("heading", { name: fixture.expected.sourceTitle, exact: true })).toBeVisible()
+  await expect(page).toHaveURL(new RegExp(`/session/${fixture.sourceID}$`))
+  await page.locator('[data-slot="titlebar-tabs"] a').filter({ hasText: "Inactive tab renamed" }).click()
+  await expect(page.getByRole("heading", { name: "Inactive tab renamed", exact: true })).toBeVisible()
+  await page.reload()
+  await expect(page.getByRole("heading", { name: "Inactive tab renamed", exact: true })).toBeVisible()
+})

packages/app/e2e/regression/session-request-docks.spec.ts

@@ -0,0 +1,221 @@
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { expect, test, type Page } from "@playwright/test"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { installSseTransport } from "../utils/sse-transport"
+import { expectSessionTitle } from "../utils/waits"
+
+const directory = "C:/OpenCode/RequestDocks"
+const projectID = "proj_request_docks"
+const sessionID = "ses_request_docks"
+const title = "Request dock regression"
+
+test("shows a pending question dock", async ({ page }) => {
+  await mockServer(page, {
+    questions: [
+      {
+        id: "question-request",
+        sessionID,
+        questions: [
+          {
+            header: "Implementation",
+            question: "Which implementation should be used?",
+            options: [
+              { label: "Minimal", description: "Use the smallest correct change" },
+              { label: "Extended", description: "Include additional behavior" },
+            ],
+          },
+        ],
+      },
+    ],
+  })
+
+  await page.goto(`/${base64Encode(directory)}/session/${sessionID}`)
+  await expectSessionTitle(page, title)
+
+  const question = page.locator('[data-component="dock-prompt"][data-kind="question"]')
+  await expect(question).toBeVisible()
+  await expect(question.getByText("Which implementation should be used?")).toBeVisible()
+  await expect(question.getByRole("radio", { name: /Minimal/ })).toBeVisible()
+  await expect(question.getByRole("radio", { name: /Extended/ })).toBeVisible()
+  await expect(page.locator('[data-component="session-composer"]')).toHaveCount(0)
+
+  const rejectRequests: string[] = []
+  page.on("request", (request) => {
+    if (request.method() !== "POST") return
+    if (new URL(request.url()).pathname === `/api/session/${sessionID}/question/question-request/reject`)
+      rejectRequests.push(request.url())
+  })
+
+  await question.locator('[data-component="icon-button"][data-icon="chevron-down"]').click()
+  await expect(question).toBeVisible()
+  await expect(question.getByText("Which implementation should be used?")).toBeVisible()
+  await expect(question.getByText("Select one answer")).toBeHidden()
+  await expect(question.getByRole("radio", { name: /Minimal/ })).toBeHidden()
+  await expect(question.getByRole("radio", { name: /Extended/ })).toBeHidden()
+  await expect(question.getByRole("button", { name: "Dismiss" })).toBeVisible()
+  await expect(question.getByRole("button", { name: "Submit" })).toBeVisible()
+  await expect(page.locator('[data-component="question-minimized-dock"]')).toHaveCount(0)
+  expect(rejectRequests).toEqual([])
+
+  await question.locator('[data-component="icon-button"][data-icon="chevron-down"]').click()
+  await expect(question).toBeVisible()
+  await expect(question.getByText("Which implementation should be used?")).toBeVisible()
+  await expect(question.getByRole("radio", { name: /Minimal/ })).toBeVisible()
+  expect(rejectRequests).toEqual([])
+
+  await question.getByRole("radio", { name: /Minimal/ }).click()
+  const reply = page.waitForRequest(
+    (request) =>
+      request.method() === "POST" &&
+      new URL(request.url()).pathname === `/api/session/${sessionID}/question/question-request/reply`,
+  )
+  await question.getByRole("button", { name: "Submit" }).click()
+  expect((await reply).postDataJSON()).toEqual({ answers: [["Minimal"]] })
+})
+
+test("shows a pending permission dock", async ({ page }) => {
+  await mockServer(page, {
+    permissions: [
+      {
+        id: "permission-request",
+        sessionID,
+        permission: "bash",
+        patterns: ["git status", "git diff"],
+        metadata: {},
+        always: [],
+      },
+    ],
+  })
+
+  await page.goto(`/${base64Encode(directory)}/session/${sessionID}`)
+  await expectSessionTitle(page, title)
+
+  const permission = page.locator('[data-component="dock-prompt"][data-kind="permission"]')
+  await expect(permission).toBeVisible()
+  await expect(permission.getByText("git status")).toBeVisible()
+  await expect(permission.getByText("git diff")).toBeVisible()
+  await expect(permission.locator('[data-slot="permission-footer-actions"] button')).toHaveCount(3)
+  await expect(page.locator('[data-component="session-composer"]')).toHaveCount(0)
+
+  const reply = page.waitForRequest((request) => request.method() === "POST")
+  await permission.getByRole("button", { name: "Allow once" }).click()
+  const request = await reply
+  expect(new URL(request.url()).pathname).toBe(`/api/session/${sessionID}/permission/permission-request/reply`)
+  expect(request.postDataJSON()).toEqual({ reply: "once" })
+})
+
+test("restores the draft caret before typing after a request dock closes", async ({ page }) => {
+  const transport = await installSseTransport(page, {
+    server: `http://${process.env.PLAYWRIGHT_SERVER_HOST ?? "127.0.0.1"}:${process.env.PLAYWRIGHT_SERVER_PORT ?? "4096"}`,
+    retry: 20,
+  })
+  await mockServer(page, { questions: [] })
+  await page.goto(`/${base64Encode(directory)}/session/${sessionID}`)
+  await transport.waitForConnection()
+  await expectSessionTitle(page, title)
+
+  const editor = page.locator('[data-component="prompt-input"][contenteditable="true"]')
+  const draft = "keep the caret at the end"
+  await editor.fill(draft)
+  await page.evaluate(() => new Promise<void>((resolve) => requestAnimationFrame(() => resolve())))
+  for (let index = 0; index < 4; index++) await page.keyboard.press("ArrowLeft")
+  const cursor = draft.length - 4
+  await expect
+    .poll(() =>
+      editor.evaluate((element) => {
+        const selection = window.getSelection()
+        if (!selection?.rangeCount || !element.contains(selection.anchorNode)) return -1
+        const range = selection.getRangeAt(0).cloneRange()
+        range.selectNodeContents(element)
+        range.setEnd(selection.anchorNode!, selection.anchorOffset)
+        return range.toString().length
+      }),
+    )
+    .toBe(cursor)
+  await transport.send({
+    directory,
+    payload: {
+      type: "question.asked",
+      properties: {
+        id: "question-caret",
+        sessionID,
+        questions: [
+          {
+            header: "Continue",
+            question: "Continue?",
+            options: [{ label: "Yes", description: "Continue the session" }],
+          },
+        ],
+        tool: { messageID: "message-caret", callID: "call-caret" },
+      },
+    },
+  })
+  const question = page.locator('[data-component="dock-prompt"][data-kind="question"]')
+  await expect(question).toBeVisible()
+  await expect(editor).toHaveCount(0)
+
+  await transport.send({
+    directory,
+    payload: { type: "question.rejected", properties: { sessionID, requestID: "question-caret" } },
+  })
+  await expect(question).toHaveCount(0)
+  await expect(editor).toBeVisible()
+  await page.keyboard.press("x")
+
+  await expect(editor).toHaveText(`${draft.slice(0, cursor)}x${draft.slice(cursor)}`)
+})
+
+async function mockServer(
+  page: Page,
+  requests: {
+    permissions?: unknown[] | (() => unknown[])
+    questions?: unknown[] | (() => unknown[])
+  },
+) {
+  await mockOpenCodeServer(page, {
+    protocol: "v2",
+    directory,
+    project: {
+      id: projectID,
+      worktree: directory,
+      vcs: "git",
+      name: "request-docks",
+      time: { created: 1700000000000, updated: 1700000000000 },
+      sandboxes: [],
+    },
+    provider: {
+      all: [
+        {
+          id: "opencode",
+          name: "OpenCode",
+          models: {
+            "claude-opus-4-6": {
+              id: "claude-opus-4-6",
+              name: "Claude Opus 4.6",
+              limit: { context: 200_000 },
+            },
+          },
+        },
+      ],
+      connected: ["opencode"],
+      default: { providerID: "opencode", modelID: "claude-opus-4-6" },
+    },
+    sessions: [
+      {
+        id: sessionID,
+        slug: "request-docks",
+        projectID,
+        directory,
+        title,
+        version: "dev",
+        time: { created: 1700000000000, updated: 1700000000000 },
+      },
+    ],
+    pageMessages: () => ({ items: [] }),
+    permissions: requests.permissions,
+    questions: requests.questions,
+  })
+  await page.addInitScript(() => {
+    localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: true } }))
+  })
+}

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

@@ -0,0 +1,22 @@
+import { expect, test } from "@playwright/test"
+import { assistantMessage, setupTimeline, shell, userMessage } from "../performance/timeline-stability/fixture"
+
+test("space activates a focused timeline button instead of scrolling", async ({ page }) => {
+  const shellID = "prt_space_button_shell"
+  await setupTimeline(page, {
+    messages: [userMessage(), assistantMessage([shell(shellID, "completed", lines(5))])],
+    settings: { shellToolPartsExpanded: false },
+    reducedMotion: true,
+  })
+  const scroller = page.locator(".scroll-view__viewport", { has: page.locator("[data-timeline-row]") })
+  const trigger = page.locator(`[data-timeline-part-id="${shellID}"] [data-slot="collapsible-trigger"]`)
+  await trigger.focus()
+  const before = await scroller.evaluate((element) => element.scrollTop)
+  await trigger.press("Space")
+  await expect(trigger).toHaveAttribute("aria-expanded", "true")
+  expect(await scroller.evaluate((element) => element.scrollTop)).toBe(before)
+})
+
+function lines(count: number) {
+  return Array.from({ length: count }, (_, index) => `line ${index + 1}`).join("\n")
+}

packages/app/e2e/regression/session-timeline-collapse-state.spec.ts

@@ -0,0 +1,439 @@
+import { expect, test, type Locator, type Page } from "@playwright/test"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectAppVisible, expectSessionTitle } from "../utils/waits"
+
+const directory = "C:/OpenCode/TimelineStateRegression"
+const projectID = "proj_timeline_state_regression"
+const sessionID = "ses_timeline_state_regression"
+const userMessageID = "msg_user_regression"
+const assistantMessageID = "msg_assistant_regression"
+const editPartID = "prt_0001_edit"
+const textPartID = "prt_9999_text"
+const title = "Timeline collapse state regression"
+const model = { providerID: "opencode", modelID: "claude-opus-4-6", variant: "max" }
+
+type EventPayload = {
+  directory: string
+  payload: Record<string, unknown>
+}
+
+declare global {
+  interface Window {
+    __timelineDiffProbe: {
+      reset: () => void
+      shadowRoots: () => number
+    }
+  }
+}
+
+const userMessage = {
+  info: {
+    id: userMessageID,
+    sessionID,
+    role: "user",
+    time: { created: 1700000000000 },
+    summary: { diffs: [] },
+    agent: "build",
+    model,
+  },
+  parts: [
+    {
+      id: "prt_user_text",
+      sessionID,
+      messageID: userMessageID,
+      type: "text",
+      text: "Please edit the file.",
+    },
+  ],
+}
+
+const editPart = {
+  id: editPartID,
+  sessionID,
+  messageID: assistantMessageID,
+  type: "tool",
+  callID: "call_edit_regression",
+  tool: "edit",
+  state: {
+    status: "completed",
+    input: { filePath: "src/regression.ts" },
+    output: "Edited src/regression.ts",
+    title: "src/regression.ts",
+    metadata: {
+      filediff: {
+        file: "src/regression.ts",
+        additions: 1,
+        deletions: 1,
+        before: "export const value = 'before'\n",
+        after: "export const value = 'after'\n",
+      },
+      diff: "diff --git a/src/regression.ts b/src/regression.ts\n-export const value = 'before'\n+export const value = 'after'\n",
+    },
+    time: { start: 1700000001000, end: 1700000002000 },
+  },
+}
+
+const streamedTextPart = {
+  id: textPartID,
+  sessionID,
+  messageID: assistantMessageID,
+  type: "text",
+  text: "Streaming added a later assistant text part.",
+}
+
+const assistantMessage = {
+  info: {
+    id: assistantMessageID,
+    sessionID,
+    role: "assistant",
+    time: { created: 1700000001000 },
+    parentID: userMessageID,
+    modelID: model.modelID,
+    providerID: model.providerID,
+    mode: "build",
+    agent: "build",
+    path: { cwd: directory, root: directory },
+    cost: 0.01,
+    tokens: { input: 100, output: 200, reasoning: 0, cache: { read: 0, write: 0 } },
+    variant: "max",
+  },
+  parts: [editPart],
+}
+
+test.describe("regression: session timeline local row state", () => {
+  test("keeps a manually collapsed tool collapsed when later assistant content streams", async ({ page }) => {
+    const events: EventPayload[] = []
+    await mockServer(page, events)
+    await configurePage(page)
+
+    await page.goto(`/${base64Encode(directory)}/session/${sessionID}`)
+    await expectSessionTitle(page, title)
+
+    const wrapper = page.locator(`[data-timeline-part-id="${editPartID}"]`).first()
+    await expectAppVisible(wrapper)
+    await expectExpanded(wrapper, true)
+
+    await wrapper.evaluate((element) => {
+      ;(element as HTMLElement).dataset.regressionMarker = "before-stream"
+    })
+    await wrapper.locator('[data-slot="collapsible-trigger"]').first().click()
+    await expectExpanded(wrapper, false)
+
+    events.push({
+      directory,
+      payload: {
+        type: "message.part.updated",
+        properties: { part: streamedTextPart },
+      },
+    })
+
+    await expect(page.locator(`[data-timeline-part-id="${textPartID}"]`).first()).toBeVisible({ timeout: 10_000 })
+
+    expect(await readToolState(page)).toEqual({
+      expanded: false,
+      row: "AssistantPart",
+      streamedTextVisible: true,
+    })
+  })
+
+  test("does not remount an edit diff when sibling parts or diff counts update", async ({ page }) => {
+    const events: EventPayload[] = []
+    await installDiffProbe(page)
+    await mockServer(page, events)
+    await configurePage(page)
+
+    await page.goto(`/${base64Encode(directory)}/session/${sessionID}`)
+    await expectSessionTitle(page, title)
+
+    const wrapper = page.locator(`[data-timeline-part-id="${editPartID}"]`).first()
+    await expectAppVisible(wrapper)
+    const file = wrapper.locator('[data-component="file"][data-mode="diff"]').first()
+    await expectAppVisible(file)
+    await markDiffProbe(page)
+
+    events.push({
+      directory,
+      payload: {
+        type: "message.part.updated",
+        properties: { part: streamedTextPart },
+      },
+    })
+
+    await expect(page.locator(`[data-timeline-part-id="${textPartID}"]`).first()).toBeVisible({ timeout: 10_000 })
+    const siblingProbe = await readDiffProbe(page)
+    expect(siblingProbe).toEqual({
+      fileMarker: "before",
+      frameMarker: "before",
+      rowKey: `assistant-part:${userMessageID}:part:${assistantMessageID}:${editPartID}`,
+      rowMarker: "before",
+      shadowRoots: 0,
+      toolMarker: "before",
+    })
+
+    await markDiffProbe(page)
+    events.push({
+      directory,
+      payload: {
+        type: "message.part.updated",
+        properties: { part: editPartWithAdditions(2) },
+      },
+    })
+
+    await expect(wrapper.locator('[data-slot="diff-changes-additions"]').filter({ hasText: "+2" }).first()).toBeVisible(
+      { timeout: 10_000 },
+    )
+    expect(await readDiffProbe(page)).toEqual({
+      fileMarker: "before",
+      frameMarker: "before",
+      rowKey: `assistant-part:${userMessageID}:part:${assistantMessageID}:${editPartID}`,
+      rowMarker: "before",
+      shadowRoots: 0,
+      toolMarker: "before",
+    })
+  })
+
+  test("keeps a sticky edit header aligned with a multi-hunk diff", async ({ page }) => {
+    const events: EventPayload[] = []
+    const lines = Array.from({ length: 1_000 }, (_, index) => `export const value${index} = ${index}\n`).join("")
+    const after = [100, 300, 500, 700, 900].reduce(
+      (result, index) =>
+        result.replace(`export const value${index} = ${index}`, `export const value${index} = compute(${index})`),
+      lines,
+    )
+    const part = {
+      ...editPart,
+      state: {
+        ...editPart.state,
+        metadata: {
+          ...editPart.state.metadata,
+          filediff: {
+            file: "src/regression.ts",
+            additions: 1,
+            deletions: 1,
+            before: lines,
+            after,
+          },
+        },
+      },
+    }
+    await mockServer(page, events, [userMessage, { ...assistantMessage, parts: [part] }])
+    await configurePage(page)
+
+    await page.goto(`/${base64Encode(directory)}/session/${sessionID}`)
+    await expectSessionTitle(page, title)
+
+    const wrapper = page.locator(`[data-timeline-part-id="${editPartID}"]`).first()
+    const trigger = wrapper.locator('[data-slot="collapsible-trigger"]').first()
+    const diff = wrapper.locator('[data-component="edit-content"]').first()
+    await expectAppVisible(diff)
+    await expect.poll(() => wrapper.evaluate((element) => element.getBoundingClientRect().height)).toBeGreaterThan(500)
+    const samples = await wrapper.evaluate(async (element) => {
+      const root = element.closest<HTMLElement>(".scroll-view__viewport")!
+      element.scrollIntoView({ block: "start" })
+      const result = []
+      for (const offset of [0, 120, 240, 360, 480]) {
+        root.scrollBy(0, offset - (result.at(-1)?.offset ?? 0))
+        await new Promise(requestAnimationFrame)
+        const trigger = element.querySelector<HTMLElement>('[data-slot="collapsible-trigger"]')!
+        const diff = element.querySelector<HTMLElement>('[data-component="edit-content"]')!
+        result.push({
+          offset,
+          trigger: trigger.getBoundingClientRect().y,
+          diff: diff.getBoundingClientRect().y,
+          bottom: element.getBoundingClientRect().bottom,
+        })
+      }
+      return result
+    })
+
+    expect(samples[0]!.trigger).toBeLessThan(samples[0]!.diff)
+    expect(samples.every((sample) => Math.abs(sample.trigger - samples[0]!.trigger) <= 1)).toBe(true)
+    expect(samples.every((sample) => sample.trigger < sample.bottom)).toBe(true)
+  })
+})
+
+async function configurePage(page: Page) {
+  await page.addInitScript(() => {
+    localStorage.setItem(
+      "settings.v3",
+      JSON.stringify({
+        general: {
+          editToolPartsExpanded: true,
+          shellToolPartsExpanded: true,
+          showReasoningSummaries: true,
+        },
+      }),
+    )
+  })
+}
+
+async function expectExpanded(locator: Locator, expected: boolean) {
+  await expect.poll(() => locator.evaluate(readExpanded)).toBe(expected)
+}
+
+async function readToolState(page: Page) {
+  return page
+    .locator(`[data-timeline-part-id="${editPartID}"]`)
+    .first()
+    .evaluate(
+      (element, textPartID) => ({
+        expanded: (() => {
+          const trigger = element.querySelector('[data-slot="collapsible-trigger"]')
+          const aria = trigger?.getAttribute("aria-expanded")
+          if (aria === "true") return true
+          if (aria === "false") return false
+
+          const root = element.querySelector('[data-component="collapsible"]')
+          if (root?.hasAttribute("data-expanded")) return true
+          if (root?.hasAttribute("data-closed")) return false
+
+          const content = element.querySelector<HTMLElement>('[data-slot="collapsible-content"]')
+          return !!content && content.getBoundingClientRect().height > 0
+        })(),
+        row: element.closest("[data-timeline-row]")?.getAttribute("data-timeline-row"),
+        streamedTextVisible: !!document.querySelector(`[data-timeline-part-id="${textPartID}"]`),
+      }),
+      textPartID,
+    )
+}
+
+async function installDiffProbe(page: Page) {
+  await page.addInitScript(() => {
+    let shadowRootCount = 0
+    const attachShadow = Element.prototype.attachShadow
+    Element.prototype.attachShadow = function (init) {
+      shadowRootCount += 1
+      return attachShadow.call(this, init)
+    }
+    window.__timelineDiffProbe = {
+      reset: () => {
+        shadowRootCount = 0
+      },
+      shadowRoots: () => shadowRootCount,
+    }
+  })
+}
+
+async function markDiffProbe(page: Page) {
+  await page
+    .locator(`[data-timeline-part-id="${editPartID}"]`)
+    .first()
+    .evaluate((element) => {
+      const tool = element as HTMLElement
+      const file = tool.querySelector<HTMLElement>('[data-component="file"][data-mode="diff"]')
+      const row = tool.closest<HTMLElement>("[data-timeline-key]")
+      const frame = tool.closest<HTMLElement>("[data-timeline-row]")
+      if (!file) throw new Error("missing edit diff file")
+      if (!row) throw new Error("missing virtual timeline row")
+      if (!frame) throw new Error("missing timeline row frame")
+
+      tool.dataset.timelineProbe = "before"
+      file.dataset.timelineProbe = "before"
+      row.dataset.timelineProbe = "before"
+      frame.dataset.timelineProbe = "before"
+      window.__timelineDiffProbe.reset()
+    })
+}
+
+async function readDiffProbe(page: Page) {
+  return page
+    .locator(`[data-timeline-part-id="${editPartID}"]`)
+    .first()
+    .evaluate((element) => {
+      const tool = element as HTMLElement
+      const file = tool.querySelector<HTMLElement>('[data-component="file"][data-mode="diff"]')
+      const row = tool.closest<HTMLElement>("[data-timeline-key]")
+      const frame = tool.closest<HTMLElement>("[data-timeline-row]")
+      return {
+        fileMarker: file?.dataset.timelineProbe,
+        shadowRoots: window.__timelineDiffProbe.shadowRoots(),
+        toolMarker: tool.dataset.timelineProbe,
+        rowMarker: row?.dataset.timelineProbe,
+        rowKey: row?.dataset.timelineKey,
+        frameMarker: frame?.dataset.timelineProbe,
+      }
+    })
+}
+
+function editPartWithAdditions(additions: number) {
+  return {
+    ...editPart,
+    state: {
+      ...editPart.state,
+      metadata: {
+        ...editPart.state.metadata,
+        filediff: {
+          ...editPart.state.metadata.filediff,
+          additions,
+        },
+      },
+    },
+  }
+}
+
+function readExpanded(element: Element) {
+  const trigger = element.querySelector('[data-slot="collapsible-trigger"]')
+  const aria = trigger?.getAttribute("aria-expanded")
+  if (aria === "true") return true
+  if (aria === "false") return false
+
+  const root = element.querySelector('[data-component="collapsible"]')
+  if (root?.hasAttribute("data-expanded")) return true
+  if (root?.hasAttribute("data-closed")) return false
+
+  const content = element.querySelector<HTMLElement>('[data-slot="collapsible-content"]')
+  return !!content && content.getBoundingClientRect().height > 0
+}
+
+async function mockServer(page: Page, events: EventPayload[], messages = [userMessage, assistantMessage]) {
+  await mockOpenCodeServer(page, {
+    directory,
+    project: project(),
+    provider: provider(),
+    sessions: [session()],
+    pageMessages: () => ({ items: messages }),
+    events: () => events.splice(0, 1),
+    eventRetry: 16,
+  })
+}
+
+function project() {
+  return {
+    id: projectID,
+    worktree: directory,
+    vcs: "git",
+    name: "timeline-state-regression",
+    time: { created: 1700000000000, updated: 1700000000000 },
+    sandboxes: [],
+  }
+}
+
+function session() {
+  return {
+    id: sessionID,
+    slug: "timeline-state-regression",
+    projectID,
+    directory,
+    title,
+    version: "dev",
+    time: { created: 1700000000000, updated: 1700000000000 },
+  }
+}
+
+function provider() {
+  return {
+    all: [
+      {
+        id: "opencode",
+        name: "OpenCode",
+        models: { "claude-opus-4-6": { id: "claude-opus-4-6", name: "Claude Opus 4.6", limit: { context: 200_000 } } },
+      },
+    ],
+    connected: ["opencode"],
+    default: { providerID: "opencode", modelID: "claude-opus-4-6" },
+  }
+}
+
+function base64Encode(value: string) {
+  return Buffer.from(value, "utf8").toString("base64").replace(/\+/g, "-").replace(/\//g, "_").replace(/=/g, "")
+}

packages/app/e2e/regression/session-timeline-context-resize.spec.ts

@@ -0,0 +1,374 @@
+import { expect, test, type Page } from "@playwright/test"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectAppVisible, expectSessionTitle } from "../utils/waits"
+import {
+  analyzeVisualObservations,
+  defineVisualRegions,
+  startVisualProbe,
+  stopVisualProbe,
+  visualPlan,
+} from "../utils/visual-stability"
+
+const directory = "C:/OpenCode/ContextResizeRegression"
+const projectID = "proj_context_resize_regression"
+const sessionID = "ses_context_resize_regression"
+const title = "Context resize regression"
+const model = { providerID: "opencode", modelID: "claude-opus-4-6", variant: "max" }
+const contextIDs = ["prt_0100_read", "prt_0101_glob", "prt_0102_grep", "prt_0103_list"]
+const followingTextID = "prt_0104_text"
+
+type Message = {
+  info: Record<string, unknown> & { id: string; role: "user" | "assistant" }
+  parts: Record<string, unknown>[]
+}
+
+const messages = [...Array.from({ length: 8 }, (_, index) => turn(index, false)).flat(), ...turn(10, true)]
+
+test.describe("regression: session timeline context group resize", () => {
+  test("remeasures a recent explored context group before the next paint", async ({ page }) => {
+    await page.setViewportSize({ width: 1400, height: 900 })
+    await mockServer(page)
+    await configurePage(page)
+
+    await page.goto(`/${base64Encode(directory)}/session/${sessionID}`)
+    await expectSessionTitle(page, title)
+    await expectAppVisible(page.locator(`[data-timeline-part-ids="${contextIDs.join(",")}"]`).first())
+    await expectAppVisible(page.locator(`[data-timeline-part-id="${followingTextID}"]`).first())
+    await settle(page)
+
+    const samples = await sampleExpansion(page)
+    const visibleOverlap = samples.filter((sample) => sample.frame >= 1 && sample.overlap > 0.5)
+
+    expect(samples[0]?.overlap).toBe(0)
+    expect(visibleOverlap).toEqual([])
+    expect(samples.at(-1)?.expanded).toBe("true")
+  })
+
+  test("paints a stable exploring to explored transition", async ({ page }) => {
+    const events: { directory: string; payload: Record<string, unknown> }[] = []
+    await page.setViewportSize({ width: 1400, height: 900 })
+    await mockServer(page, events, [
+      ...Array.from({ length: 8 }, (_, index) => turn(index, false)).flat(),
+      ...turn(10, true, "running"),
+    ])
+    await configurePage(page)
+
+    await page.goto(`/${base64Encode(directory)}/session/${sessionID}`)
+    await expectSessionTitle(page, title)
+    const devtools = await page.context().newCDPSession(page)
+    await devtools.send("Emulation.setCPUThrottlingRate", { rate: 4 })
+    const context = page.locator(`[data-timeline-part-ids="${contextIDs.join(",")}"]`).first()
+    await expectAppVisible(context)
+    await expect(context.locator('[data-component="tool-status-title"]')).toHaveAttribute("aria-label", "Exploring")
+
+    const contextSelector = `[data-timeline-part-ids="${contextIDs.join(",")}"]`
+    const regions = defineVisualRegions({
+      status: {
+        selector: `${contextSelector} [data-component="tool-status-title"]`,
+        opacitySelectors: ['[data-slot="tool-status-active"]', '[data-slot="tool-status-done"]'],
+      },
+      context: { selector: contextSelector, closest: '[data-timeline-row="AssistantPart"]' },
+      following: {
+        selector: `[data-timeline-part-id="${followingTextID}"]`,
+        closest: '[data-timeline-row="AssistantPart"]',
+      },
+    })
+    await startVisualProbe(page, regions)
+    for (const [index, delay] of [120, 350, 80, 500].entries()) {
+      events.push({
+        directory,
+        payload: {
+          type: "message.part.updated",
+          properties: {
+            part: contextTool(
+              contextIDs[index]!,
+              id("msg_assistant", 10),
+              ["read", "glob", "grep", "list"][index]!,
+              [
+                { filePath: "src/recent-a.ts" },
+                { path: directory, pattern: "**/*.ts" },
+                { path: directory, pattern: "Explored" },
+                { path: "src" },
+              ][index]!,
+            ),
+          },
+        },
+      })
+      await page.waitForTimeout(delay)
+    }
+
+    await expect(context.locator('[data-component="tool-status-title"]')).toHaveAttribute("aria-label", "Explored")
+    await page.waitForTimeout(700)
+    const trace = await stopVisualProbe<keyof typeof regions>(page)
+    const labels = trace.samples
+      .map((sample) => sample.regions.status?.label)
+      .filter((value): value is string => !!value)
+      .filter((value, index, all) => value !== all[index - 1])
+    const issues = analyzeVisualObservations(
+      trace.samples,
+      visualPlan(regions, [
+        { type: "required", regions: ["context", "following"] },
+        { type: "opacity", regions: "all" },
+        { type: "continuity", regions: "all" },
+        { type: "motion", regions: "all" },
+        { type: "label-stability", regions: "all" },
+        { type: "flow", regions: ["context", "following"] },
+      ]),
+    )
+
+    expect(labels).toEqual(["Exploring", "Explored"])
+    expect(issues, JSON.stringify(trace.samples, null, 2)).toEqual([])
+  })
+})
+
+async function configurePage(page: Page) {
+  await page.addInitScript(() => {
+    localStorage.setItem(
+      "settings.v3",
+      JSON.stringify({
+        general: {
+          editToolPartsExpanded: true,
+          shellToolPartsExpanded: true,
+          showReasoningSummaries: true,
+        },
+      }),
+    )
+  })
+}
+
+async function sampleExpansion(page: Page) {
+  return page.evaluate(
+    ({ contextIDs, followingTextID }) =>
+      new Promise<
+        {
+          frame: number
+          label: string
+          scrollTop: number
+          scrollHeight: number
+          contextBottom: number
+          textTop: number
+          overlap: number
+          gap: number
+          expanded: string | null
+        }[]
+      >((resolve) => {
+        const context = document.querySelector<HTMLElement>(`[data-timeline-part-ids="${contextIDs.join(",")}"]`)
+        const text = document.querySelector<HTMLElement>(`[data-timeline-part-id="${followingTextID}"]`)
+        const scroller = context?.closest<HTMLElement>(".scroll-view__viewport")
+        const trigger = context?.querySelector<HTMLElement>('[data-slot="collapsible-trigger"]')
+        const contextRow = context?.closest<HTMLElement>('[data-timeline-row="AssistantPart"]')
+        const textRow = text?.closest<HTMLElement>('[data-timeline-row="AssistantPart"]')
+        if (!context || !text || !scroller || !trigger || !contextRow || !textRow)
+          throw new Error("missing regression nodes")
+
+        scroller.scrollTop = scroller.scrollHeight
+        const samples: {
+          frame: number
+          label: string
+          scrollTop: number
+          scrollHeight: number
+          contextBottom: number
+          textTop: number
+          overlap: number
+          gap: number
+          expanded: string | null
+        }[] = []
+        const capture = (frame: number, label: string) => {
+          const contextRect = contextRow.getBoundingClientRect()
+          const textRect = textRow.getBoundingClientRect()
+          samples.push({
+            frame,
+            label,
+            scrollTop: Math.round(scroller.scrollTop * 10) / 10,
+            scrollHeight: Math.round(scroller.scrollHeight * 10) / 10,
+            contextBottom: Math.round(contextRect.bottom * 10) / 10,
+            textTop: Math.round(textRect.top * 10) / 10,
+            overlap: Math.max(0, Math.round((contextRect.bottom - textRect.top) * 10) / 10),
+            gap: Math.max(0, Math.round((textRect.top - contextRect.bottom) * 10) / 10),
+            expanded: trigger.getAttribute("aria-expanded"),
+          })
+        }
+
+        capture(-1, "before")
+        trigger.click()
+        capture(0, "sync-after-click")
+
+        let frame = 1
+        const tick = () => {
+          setTimeout(() => {
+            capture(frame, "painted")
+            frame += 1
+            if (frame > 8) {
+              resolve(samples)
+              return
+            }
+            requestAnimationFrame(tick)
+          }, 0)
+        }
+        requestAnimationFrame(tick)
+      }),
+    { contextIDs, followingTextID },
+  )
+}
+
+function turn(index: number, target: boolean, status: "running" | "completed" = "completed"): Message[] {
+  const userID = id("msg_user", index)
+  const assistantID = id("msg_assistant", index)
+  return [
+    {
+      info: {
+        id: userID,
+        sessionID,
+        role: "user",
+        time: { created: 1700000000000 + index * 10_000 },
+        summary: { diffs: [] },
+        agent: "build",
+        model,
+      },
+      parts: [{ id: id("prt_user", index), sessionID, messageID: userID, type: "text", text: `User message ${index}` }],
+    },
+    {
+      info: {
+        id: assistantID,
+        sessionID,
+        role: "assistant",
+        time: { created: 1700000000000 + index * 10_000 + 1_000, completed: 1700000000000 + index * 10_000 + 2_000 },
+        parentID: userID,
+        modelID: model.modelID,
+        providerID: model.providerID,
+        mode: "build",
+        agent: "build",
+        path: { cwd: directory, root: directory },
+        cost: 0.01,
+        tokens: { input: 100, output: 200, reasoning: 0, cache: { read: 0, write: 0 } },
+        variant: "max",
+        finish: "stop",
+      },
+      parts: target
+        ? [
+            contextTool(
+              contextIDs[0]!,
+              assistantID,
+              "read",
+              { filePath: "src/recent-a.ts", offset: 0, limit: 120 },
+              status,
+            ),
+            contextTool(contextIDs[1]!, assistantID, "glob", { path: directory, pattern: "**/*.ts" }, status),
+            contextTool(
+              contextIDs[2]!,
+              assistantID,
+              "grep",
+              { path: directory, pattern: "Explored", include: "*.ts" },
+              status,
+            ),
+            contextTool(contextIDs[3]!, assistantID, "list", { path: "src" }, status),
+            {
+              id: followingTextID,
+              sessionID,
+              messageID: assistantID,
+              type: "text",
+              text: "This assistant text is immediately after the explored context group.",
+            },
+          ]
+        : [
+            {
+              id: id("prt_text", index),
+              sessionID,
+              messageID: assistantID,
+              type: "text",
+              text: `Assistant filler ${index}. ${"filler ".repeat(60)}`,
+            },
+          ],
+    },
+  ]
+}
+
+function contextTool(
+  partID: string,
+  messageID: string,
+  tool: string,
+  input: Record<string, unknown>,
+  status: "running" | "completed" = "completed",
+) {
+  return {
+    id: partID,
+    sessionID,
+    messageID,
+    type: "tool",
+    callID: `call_${partID}`,
+    tool,
+    state: {
+      status,
+      input,
+      output: `Completed ${tool}.\n${"detail line\n".repeat(8)}`,
+      title: input.filePath || input.path || input.pattern || "completed",
+      metadata: {},
+      time: { start: 1700000000000, end: 1700000000100 },
+    },
+  }
+}
+
+async function mockServer(
+  page: Page,
+  events: { directory: string; payload: Record<string, unknown> }[] = [],
+  fixtureMessages = messages,
+) {
+  await mockOpenCodeServer(page, {
+    directory,
+    project: project(),
+    provider: provider(),
+    sessions: [session()],
+    pageMessages: () => ({ items: fixtureMessages }),
+    events: () => events.splice(0, 1),
+    eventRetry: 50,
+  })
+}
+
+async function settle(page: Page) {
+  await page.evaluate(() => new Promise((resolve) => requestAnimationFrame(() => requestAnimationFrame(resolve))))
+}
+
+function id(prefix: string, index: number) {
+  return `${prefix}_${String(index).padStart(4, "0")}`
+}
+
+function project() {
+  return {
+    id: projectID,
+    worktree: directory,
+    vcs: "git",
+    name: "context-resize-regression",
+    time: { created: 1700000000000, updated: 1700000000000 },
+    sandboxes: [],
+  }
+}
+
+function session() {
+  return {
+    id: sessionID,
+    slug: "context-resize-regression",
+    projectID,
+    directory,
+    title,
+    version: "dev",
+    time: { created: 1700000000000, updated: 1700000000000 },
+  }
+}
+
+function provider() {
+  return {
+    all: [
+      {
+        id: "opencode",
+        name: "OpenCode",
+        models: { "claude-opus-4-6": { id: "claude-opus-4-6", name: "Claude Opus 4.6", limit: { context: 200_000 } } },
+      },
+    ],
+    connected: ["opencode"],
+    default: { providerID: "opencode", modelID: "claude-opus-4-6" },
+  }
+}
+
+function base64Encode(value: string) {
+  return Buffer.from(value, "utf8").toString("base64").replace(/\+/g, "-").replace(/\//g, "_").replace(/=/g, "")
+}

packages/app/e2e/regression/session-timeline-context-state.spec.ts

@@ -0,0 +1,31 @@
+import { expect, test } from "@playwright/test"
+import {
+  assistantMessage,
+  partUpdated,
+  setupTimeline,
+  toolPart,
+  userMessage,
+} from "../performance/timeline-stability/fixture"
+
+test("preserves a collapsed context group through count and status updates", async ({ page }) => {
+  const ids = ["prt_closed_01_read", "prt_closed_02_glob"]
+  const inputs = {
+    read: { filePath: "src/a.ts", offset: 0, limit: 120 },
+    glob: { path: ".", pattern: "**/*.ts" },
+  }
+  const timeline = await setupTimeline(page, {
+    messages: [
+      userMessage(),
+      assistantMessage(
+        [toolPart(ids[0]!, "read", "running", inputs.read), toolPart(ids[1]!, "glob", "running", inputs.glob)],
+        { completed: false },
+      ),
+    ],
+  })
+  const group = page.locator(`[data-timeline-part-ids="${ids.join(",")}"]`)
+  const trigger = group.locator('[data-slot="collapsible-trigger"]')
+  await expect(trigger).toHaveAttribute("aria-expanded", "false")
+  await timeline.send(partUpdated(toolPart(ids[0]!, "read", "completed", inputs.read)), 100)
+  await timeline.send(partUpdated(toolPart(ids[1]!, "glob", "completed", inputs.glob)), 300)
+  await expect(trigger).toHaveAttribute("aria-expanded", "false")
+})

packages/app/e2e/regression/session-timeline-file-projection.spec.ts

@@ -0,0 +1,52 @@
+import { expect, test } from "@playwright/test"
+import { assistantMessage, setupTimeline, toolPart, userMessage } from "../performance/timeline-stability/fixture"
+
+test("renders completed write content", async ({ page }) => {
+  const id = "prt_file_projection_write"
+  await setupTimeline(page, {
+    messages: [
+      userMessage(),
+      assistantMessage([
+        toolPart(id, "write", "completed", { filePath: "src/write.ts", content: "export const written = true\n" }),
+      ]),
+    ],
+    settings: { editToolPartsExpanded: true },
+  })
+
+  await expect(page.locator(`[data-timeline-part-id="${id}"] [data-component="write-content"]`)).toBeVisible()
+})
+
+test("renders a completed single-file patch", async ({ page }) => {
+  const id = "prt_file_projection_single_patch"
+  await setupTimeline(page, {
+    messages: [
+      userMessage(),
+      assistantMessage([
+        toolPart(
+          id,
+          "apply_patch",
+          "completed",
+          { files: ["src/a.ts"] },
+          {
+            metadata: {
+              files: [
+                {
+                  filePath: "src/a.ts",
+                  relativePath: "src/a.ts",
+                  type: "update",
+                  additions: 1,
+                  deletions: 1,
+                  before: "export const value = 1\n",
+                  after: "export const value = 2\n",
+                },
+              ],
+            },
+          },
+        ),
+      ]),
+    ],
+    settings: { editToolPartsExpanded: true },
+  })
+
+  await expect(page.locator(`[data-timeline-part-id="${id}"] [data-component="apply-patch-file-diff"]`)).toBeVisible()
+})

packages/app/e2e/regression/session-timeline-file-state.spec.ts

@@ -0,0 +1,94 @@
+import { expect, test } from "@playwright/test"
+import {
+  assistantMessage,
+  partUpdated,
+  setupTimeline,
+  toolPart,
+  userMessage,
+} from "../performance/timeline-stability/fixture"
+
+test("updates edit diagnostics without resetting manual collapse state", async ({ page }) => {
+  const editID = "prt_diagnostics_edit"
+  const base = editPart(editID, [])
+  const timeline = await setupTimeline(page, {
+    messages: [userMessage(), assistantMessage([base])],
+    settings: { editToolPartsExpanded: true },
+  })
+  const trigger = page.locator(`[data-timeline-part-id="${editID}"] [data-slot="collapsible-trigger"]`).first()
+  await trigger.click()
+  await expect(trigger).toHaveAttribute("aria-expanded", "false")
+  await timeline.send(
+    partUpdated(editPart(editID, [diagnostic("First failure", 2), diagnostic("Second failure", 4)])),
+    300,
+  )
+  await expect(trigger).toHaveAttribute("aria-expanded", "false")
+  await timeline.send(partUpdated(editPart(editID, [])), 300)
+  await expect(trigger).toHaveAttribute("aria-expanded", "false")
+})
+
+test("preserves nested patch file state through outer collapse and reopen", async ({ page }) => {
+  const patchID = "prt_nested_patch"
+  const files = [patchFile("src/a.ts", "update"), patchFile("src/b.ts", "add"), patchFile("src/old.ts", "delete")]
+  await setupTimeline(page, {
+    messages: [
+      userMessage(),
+      assistantMessage([
+        toolPart(
+          patchID,
+          "apply_patch",
+          "completed",
+          { files: files.map((file) => file.filePath) },
+          { metadata: { files } },
+        ),
+      ]),
+    ],
+    settings: { editToolPartsExpanded: true },
+  })
+  const wrapper = page.locator(`[data-timeline-part-id="${patchID}"]`)
+  const outer = wrapper.locator('[data-slot="collapsible-trigger"]').first()
+  const deleted = wrapper.locator('[data-scope="apply-patch"] [data-type="delete"]')
+  await deleted.getByRole("button").click()
+  await expect(deleted.getByRole("button")).toHaveAttribute("aria-expanded", "true")
+  await outer.click()
+  await expect(outer).toHaveAttribute("aria-expanded", "false")
+  await outer.click()
+  await expect(outer).toHaveAttribute("aria-expanded", "true")
+  await expect(deleted.getByRole("button")).toHaveAttribute("aria-expanded", "true")
+})
+
+function patchFile(filePath: string, type: "add" | "update" | "delete") {
+  return {
+    filePath,
+    relativePath: filePath,
+    type,
+    additions: type === "delete" ? 0 : 4,
+    deletions: type === "add" ? 0 : 3,
+    before: type === "add" ? undefined : source(false),
+    after: type === "delete" ? undefined : source(true),
+  }
+}
+
+function editPart(id: string, diagnostics: Record<string, unknown>[]) {
+  return toolPart(
+    id,
+    "edit",
+    "completed",
+    { filePath: "src/edit.ts" },
+    {
+      metadata: {
+        filediff: { file: "src/edit.ts", additions: 1, deletions: 1, before: source(false), after: source(true) },
+        diagnostics,
+      },
+    },
+  )
+}
+
+function diagnostic(message: string, line: number) {
+  return { message, severity: 1, range: { start: { line, character: 0 }, end: { line, character: 2 } } }
+}
+
+function source(changed: boolean) {
+  return Array.from({ length: 12 }, (_, index) => `export const value${index} = ${changed ? index + 1 : index}\n`).join(
+    "",
+  )
+}

packages/app/e2e/regression/session-timeline-history-root.spec.ts

@@ -0,0 +1,242 @@
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { expect, test, type Page } from "@playwright/test"
+import {
+  assistantMessage,
+  directory,
+  messageUpdated,
+  project,
+  session,
+  sessionID,
+  status,
+  textPart,
+  title,
+  userID,
+  userMessage,
+} from "../performance/timeline-stability/fixture"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { installSseTransport } from "../utils/sse-transport"
+import { expectSessionTitle } from "../utils/waits"
+
+const initialPageSize = 20
+const historyPageSize = 200
+const assistants = Array.from({ length: initialPageSize + 1 }, (_, index) =>
+  assistantMessage([textPart(`prt_history_root_${index}`, `Assistant response ${index}`)], {
+    id: `msg_${String(index + 1001).padStart(4, "0")}_history_root_assistant`,
+    parentID: userID,
+    created: 1700000001000 + index * 1_000,
+    completed: index < initialPageSize,
+  }),
+)
+const messages = [userMessage(), ...assistants]
+const lastAssistant = assistants.at(-1)!
+const lastPartID = assistants.at(-1)!.parts[0]!.id
+const userPartID = `prt_${userID}_text`
+const completed = {
+  ...lastAssistant.info,
+  time: { ...lastAssistant.info.time, completed: lastAssistant.info.time.created + 15_000 },
+}
+const scenarios = [
+  { name: "completion", info: completed, idleFirst: false, interrupted: false },
+  {
+    name: "interruption",
+    info: { ...completed, error: { name: "MessageAbortedError", data: { message: "Stopped" } } },
+    idleFirst: true,
+    interrupted: true,
+  },
+] as const
+
+test.use({ viewport: { width: 646, height: 1385 } })
+
+for (const scenario of scenarios) {
+  test(`keeps visible timeline content visible through ${scenario.name}`, async ({ page }) => {
+    const requests: { before?: string; phase: "start" | "end" }[] = []
+    const pages: { before?: string; limit: number }[] = []
+    const roots: { sessionID: string; messageID: string }[] = []
+    const sequence: string[] = []
+    const history = Promise.withResolvers<void>()
+    const transport = await installSseTransport<{ directory: string; payload: Record<string, unknown> }>(page, {
+      server: `http://${process.env.PLAYWRIGHT_SERVER_HOST ?? "127.0.0.1"}:${process.env.PLAYWRIGHT_SERVER_PORT ?? "4096"}`,
+      retry: 20,
+    })
+    await mockOpenCodeServer(page, {
+      directory,
+      project: project(),
+      provider: {
+        all: [
+          {
+            id: "opencode",
+            name: "OpenCode",
+            models: {
+              "claude-opus-4-6": {
+                id: "claude-opus-4-6",
+                name: "Claude Opus 4.6",
+                limit: { context: 200_000 },
+              },
+            },
+          },
+        ],
+        connected: ["opencode"],
+        default: { providerID: "opencode", modelID: "claude-opus-4-6" },
+      },
+      sessions: [session()],
+      sessionStatus: { [sessionID]: { type: "busy" } },
+      beforeMessagesResponse: (request) => (request.before ? history.promise : Promise.resolve()),
+      onMessages: (request) => {
+        requests.push(request)
+        sequence.push(`messages:${request.phase}:${request.before ?? "latest"}`)
+      },
+      onMessage: (request) => {
+        roots.push(request)
+        sequence.push(`message:${request.messageID}`)
+      },
+      message: (requestedSessionID, messageID) => {
+        if (requestedSessionID !== sessionID) return
+        return messages.find((item) => item.info.id === messageID)
+      },
+      pageMessages: (_, limit, before) => {
+        pages.push({ before, limit })
+        const end = before ? messages.findIndex((message) => message.info.id === before) : messages.length
+        const start = Math.max(0, end - limit)
+        return {
+          items: messages.slice(start, end),
+          cursor: start > 0 ? messages[start]!.info.id : undefined,
+        }
+      },
+    })
+    await page.addInitScript(() => {
+      const visibleParts = () => {
+        const virtual = document.querySelector<HTMLElement>("[data-timeline-virtual-content]")
+        const viewport = virtual?.closest<HTMLElement>(".scroll-view__viewport")
+        const view = viewport?.getBoundingClientRect()
+        if (!viewport || !view) return []
+        return [...viewport.querySelectorAll<HTMLElement>("[data-timeline-part-id]")]
+          .filter((part) => {
+            const rect = part.getBoundingClientRect()
+            return rect.width > 0 && rect.height > 0 && rect.bottom > view.top && rect.top < view.bottom
+          })
+          .flatMap((part) => (part.dataset.timelinePartId ? [part.dataset.timelinePartId] : []))
+      }
+      const state = {
+        armed: false,
+        hidden: false,
+        visibleParts: [] as string[],
+        samples: 0,
+        stop: false,
+        arm() {
+          state.visibleParts = visibleParts()
+          state.armed = true
+        },
+      }
+      ;(window as Window & { __historyRootProbe?: typeof state }).__historyRootProbe = state
+      const sample = () => {
+        if (state.armed) {
+          const virtual = document.querySelector<HTMLElement>("[data-timeline-virtual-content]")
+          const viewport = virtual?.closest<HTMLElement>(".scroll-view__viewport")
+          const view = viewport?.getBoundingClientRect()
+          const visible = (partID: string) => {
+            const part = viewport?.querySelector<HTMLElement>(`[data-timeline-part-id="${CSS.escape(partID)}"]`)
+            const rect = part?.getBoundingClientRect()
+            return (
+              !!rect && !!view && rect.width > 0 && rect.height > 0 && rect.bottom > view.top && rect.top < view.bottom
+            )
+          }
+          if (!virtual || state.visibleParts.length === 0 || state.visibleParts.some((partID) => !visible(partID)))
+            state.hidden = true
+          state.samples++
+        }
+        if (!state.stop) requestAnimationFrame(() => setTimeout(sample, 0))
+      }
+      requestAnimationFrame(() => setTimeout(sample, 0))
+    })
+
+    await page.goto(`/${base64Encode(directory)}/session/${sessionID}`)
+    await transport.waitForConnection()
+    await expectSessionTitle(page, title)
+    await expect(page.locator(`[data-timeline-part-id="${lastPartID}"]`)).toBeVisible()
+    await expect(page.locator(`[data-timeline-part-id="${userPartID}"]`)).toBeVisible()
+    await expect.poll(() => requests.filter((request) => request.phase === "start").length).toBe(2)
+    expect(requests.filter((request) => request.phase === "end")).toHaveLength(1)
+    expect(sequence.slice(0, 4)).toEqual([
+      "messages:start:latest",
+      "messages:end:latest",
+      `message:${userID}`,
+      `messages:start:${messages.at(-initialPageSize)!.info.id}`,
+    ])
+    await expect(page.locator('[data-timeline-part-id^="prt_history_root_"]')).toHaveCount(initialPageSize)
+    await page.evaluate(() => {
+      ;(
+        window as Window & {
+          __historyRootProbe?: { arm(): void }
+        }
+      ).__historyRootProbe!.arm()
+    })
+    await waitForProbeSamples(page, 0)
+    expect(await visibleContentHidden(page)).toBe(false)
+    const beforeHistory = await probeSamples(page)
+    history.resolve()
+    await expect(page.locator('[data-timeline-part-id^="prt_history_root_"]')).toHaveCount(assistants.length)
+    await expect.poll(() => requests.filter((request) => request.phase === "end").length).toBe(2)
+    await expect(page.getByRole("button", { name: "Stop" })).toBeVisible()
+    await waitForProbeSamples(page, beforeHistory)
+    expect(pages).toEqual([
+      { before: undefined, limit: initialPageSize },
+      { before: messages.at(-initialPageSize)!.info.id, limit: historyPageSize },
+    ])
+    expect(roots).toEqual([{ sessionID, messageID: userID }])
+
+    const message = messageUpdated(scenario.info)
+    const idle = status("idle")
+    for (const event of scenario.idleFirst ? [idle, message] : [message, idle]) {
+      const beforeEvent = await probeSamples(page)
+      await transport.send(event)
+      if (event === idle) await expect(page.getByRole("button", { name: "Stop" })).toHaveCount(0)
+      if (event === message && scenario.interrupted)
+        await expect(page.getByText("Interrupted", { exact: true })).toBeVisible()
+      await waitForProbeSamples(page, beforeEvent)
+      const current = await timelineState(page)
+      expect(current, JSON.stringify(current)).toMatchObject({ virtual: true })
+      expect(current.rows, JSON.stringify(current)).toBeGreaterThan(0)
+    }
+
+    expect(requests[0]).toEqual({ before: undefined, phase: "start", sessionID })
+    expect(requests[1]).toEqual({ before: undefined, phase: "end", sessionID })
+    await expect(page.getByRole("button", { name: "Stop" })).toHaveCount(0)
+    await expect(page.locator('[data-timeline-row="bottom-spacer"]')).toBeVisible()
+    if (scenario.interrupted) await expect(page.getByText("Interrupted", { exact: true })).toBeVisible()
+    expect(
+      await page.evaluate(() => {
+        const state = (window as Window & { __historyRootProbe?: { hidden: boolean; stop: boolean } })
+          .__historyRootProbe!
+        state.stop = true
+        return state.hidden
+      }),
+    ).toBe(false)
+  })
+}
+
+function timelineState(page: Page) {
+  return page.evaluate(() => ({
+    virtual: !!document.querySelector("[data-timeline-virtual-content]"),
+    rows: document.querySelectorAll("[data-timeline-key]").length,
+  }))
+}
+
+function probeSamples(page: Page) {
+  return page.evaluate(
+    () => (window as Window & { __historyRootProbe?: { samples: number } }).__historyRootProbe!.samples,
+  )
+}
+
+async function waitForProbeSamples(page: Page, after: number) {
+  await page.waitForFunction(
+    (after) =>
+      (window as Window & { __historyRootProbe?: { samples: number } }).__historyRootProbe!.samples >= after + 3,
+    after,
+  )
+}
+
+function visibleContentHidden(page: Page) {
+  return page.evaluate(
+    () => (window as Window & { __historyRootProbe?: { hidden: boolean } }).__historyRootProbe!.hidden,
+  )
+}

packages/app/e2e/regression/session-timeline-lifecycle-state.spec.ts

@@ -0,0 +1,111 @@
+import { expect, test } from "@playwright/test"
+import {
+  assistantMessage,
+  completedAssistantInfo,
+  messageUpdated,
+  partUpdated,
+  reasoningPart,
+  setupTimeline,
+  shell,
+  status,
+  textPart,
+  userMessage,
+} from "../performance/timeline-stability/fixture"
+
+for (const expanded of [false, true]) {
+  test(`preserves shell user intent from a ${expanded ? "expanded" : "collapsed"} default`, async ({ page }) => {
+    const id = `prt_shell_default_${expanded}`
+    const timeline = await setupTimeline(page, {
+      messages: [userMessage(), assistantMessage([shell(id, "completed", lines(3))])],
+      settings: { shellToolPartsExpanded: expanded },
+    })
+    const trigger = page.locator(`[data-timeline-part-id="${id}"] [data-slot="collapsible-trigger"]`)
+    await expect(trigger).toHaveAttribute("aria-expanded", String(expanded))
+    await trigger.click()
+    await expect(trigger).toHaveAttribute("aria-expanded", String(!expanded))
+
+    await timeline.send(partUpdated(shell(id, "completed", lines(6))), 180)
+    await timeline.send(partUpdated(textPart(`prt_sibling_${expanded}`, "Sibling content")), 180)
+    await timeline.send(status("busy"), 100)
+    await timeline.send(status("idle"), 250)
+    await expect(trigger).toHaveAttribute("aria-expanded", String(!expanded))
+  })
+}
+
+test("shows and expands a running shell command without shimmering it", async ({ page }) => {
+  const id = "prt_shell_running_command"
+  const command = "sleep 10 && echo done"
+  await setupTimeline(page, {
+    messages: [userMessage(), assistantMessage([shell(id, "running", "still running", command)], { completed: false })],
+    settings: { shellToolPartsExpanded: false },
+  })
+
+  const tool = page.locator(`[data-timeline-part-id="${id}"]`)
+  await expect(tool.locator('[data-component="text-shimmer"]')).toHaveAttribute("data-active", "true")
+  await expect(tool.locator('[data-component="shell-submessage"]')).toHaveText(command)
+  await expect(tool.locator('[data-component="shell-submessage"] [data-component="text-shimmer"]')).toHaveCount(0)
+  await tool.locator('[data-slot="collapsible-trigger"]').click()
+  await expect(tool.locator('[data-slot="collapsible-trigger"]')).toHaveAttribute("aria-expanded", "true")
+  await expect(tool.locator('[data-slot="bash-pre"]')).toContainText("still running")
+})
+
+test("transitions thinking and hidden reasoning through busy to idle", async ({ page }) => {
+  const reasoningID = "prt_reasoning_hidden"
+  const assistant = assistantMessage([reasoningPart(reasoningID, "## Inspecting stability")], { completed: false })
+  const timeline = await setupTimeline(page, {
+    messages: [userMessage(), assistant],
+    settings: { showReasoningSummaries: false },
+    cpuRate: 4,
+  })
+  await timeline.send(status("busy"), 150)
+
+  await expect(page.locator('[data-timeline-row="Thinking"]')).toBeVisible()
+  await expect(page.getByText("Inspecting stability", { exact: true })).toBeVisible()
+  await expect(page.locator(`[data-timeline-part-id="${reasoningID}"]`)).toHaveCount(0)
+  await timeline.send(partUpdated(shell("prt_reasoning_shell", "running")), 160)
+  await expect(page.locator('[data-timeline-row="Thinking"]')).toBeVisible()
+  await timeline.send(partUpdated(shell("prt_reasoning_shell", "completed", "done")), 180)
+  await timeline.send(messageUpdated(completedAssistantInfo(assistant.info)), 100)
+  await timeline.send(status("idle"), 300)
+  await expect(page.locator('[data-timeline-row="Thinking"]')).toHaveCount(0)
+  await expect(page.locator(`[data-timeline-part-id="${reasoningID}"]`)).toHaveCount(0)
+})
+
+test("moves busy through retry and recovery to final idle content", async ({ page }) => {
+  const assistant = assistantMessage([], { completed: false })
+  const timeline = await setupTimeline(page, {
+    messages: [
+      userMessage(undefined, {
+        summary: {
+          diffs: [
+            {
+              file: "src/retry.ts",
+              additions: 1,
+              deletions: 1,
+              patch: "@@ -1 +1 @@\n-export const retry = false\n+export const retry = true",
+            },
+          ],
+        },
+      }),
+      assistant,
+    ],
+  })
+  await timeline.send(status("busy"), 140)
+  await expect(page.locator('[data-timeline-row="Thinking"]')).toBeVisible()
+  await expect(page.locator('[data-timeline-row="DiffSummary"]')).toHaveCount(0)
+  await timeline.send(status("retry"), 180)
+  await expect(page.locator('[data-timeline-row="Retry"]')).toBeVisible()
+  await expect(page.locator('[data-timeline-row="Thinking"]')).toHaveCount(0)
+  await timeline.send(status("busy", 2), 180)
+  await expect(page.locator('[data-timeline-row="Thinking"]')).toBeVisible()
+  await timeline.send(partUpdated(textPart("prt_recovered", "Recovered response")), 140)
+  await timeline.send(messageUpdated(completedAssistantInfo(assistant.info)), 100)
+  await timeline.send(status("idle"), 350)
+  await expect(page.locator('[data-timeline-row="Retry"]')).toHaveCount(0)
+  await expect(page.locator('[data-timeline-row="Thinking"]')).toHaveCount(0)
+  await expect(page.locator('[data-timeline-row="DiffSummary"]')).toBeVisible()
+})
+
+function lines(count: number) {
+  return Array.from({ length: count }, (_, index) => `line ${index + 1}`).join("\n")
+}

packages/app/e2e/regression/session-timeline-locale-projection.spec.ts

@@ -0,0 +1,25 @@
+import { expect, test } from "@playwright/test"
+import { assistantMessage, setupTimeline, toolPart, userMessage } from "../performance/timeline-stability/fixture"
+
+for (const profile of [
+  { locale: "de", label: "Erkundung abgeschlossen" },
+  { locale: "ar", label: "تم الاستكشاف" },
+] as const) {
+  test(`projects translated context status in ${profile.locale}`, async ({ page }) => {
+    const ids = [`prt_locale_${profile.locale}_01_read`, `prt_locale_${profile.locale}_02_glob`]
+    await setupTimeline(page, {
+      messages: [
+        userMessage(),
+        assistantMessage([
+          toolPart(ids[0]!, "read", "completed", { filePath: "src/a.ts" }),
+          toolPart(ids[1]!, "glob", "completed", { path: ".", pattern: "**/*.ts" }),
+        ]),
+      ],
+      locale: profile.locale,
+    })
+
+    const group = page.locator(`[data-timeline-part-ids="${ids.join(",")}"]`)
+    await expect(group.locator('[data-component="tool-status-title"]')).toHaveAttribute("aria-label", profile.label)
+    await expect(page.locator("html")).toHaveAttribute("lang", profile.locale)
+  })
+}

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

@@ -0,0 +1,283 @@
+import { expect, test } from "@playwright/test"
+import {
+  assistantMessage,
+  setupTimeline,
+  status,
+  toolPart,
+  userMessage,
+  userText,
+  type PartSeed,
+} from "../performance/timeline-stability/fixture"
+
+test.describe("session timeline projection", () => {
+  test("renders every admitted tool family and hides timeline-only exclusions", async ({ page }) => {
+    const parts = [
+      toolPart("prt_01_read", "read", "completed", { filePath: "src/a.ts" }),
+      toolPart("prt_02_glob", "glob", "completed", { path: ".", pattern: "**/*.ts" }),
+      toolPart("prt_03_grep", "grep", "completed", { path: ".", pattern: "value" }),
+      toolPart("prt_04_list", "list", "completed", { path: "src" }),
+      toolPart("prt_webfetch", "webfetch", "completed", { url: "https://example.com" }),
+      toolPart(
+        "prt_websearch",
+        "websearch",
+        "completed",
+        { query: "timeline stability" },
+        { output: "https://example.com/result" },
+      ),
+      toolPart("prt_task", "task", "completed", { description: "Inspect timeline", subagent_type: "explore" }),
+      toolPart(
+        "prt_bash",
+        "bash",
+        "completed",
+        { command: "printf stable" },
+        { output: "stable", title: "printf stable" },
+      ),
+      editPart("prt_edit"),
+      toolPart("prt_write", "write", "completed", { filePath: "src/new.ts", content: "export const stable = true\n" }),
+      patchPart("prt_patch"),
+      toolPart("prt_todo", "todowrite", "completed", { todos: [{ content: "Hidden", status: "pending" }] }),
+      toolPart(
+        "prt_question",
+        "question",
+        "completed",
+        { questions: [{ question: "Keep stable?", header: "Stability", options: [] }] },
+        { metadata: { answers: [["Yes"]] } },
+      ),
+      toolPart("prt_skill", "skill", "completed", { name: "stability" }),
+      toolPart("prt_custom", "custom_mcp_tool", "completed", { target: "timeline", count: 2 }),
+    ]
+    await setupTimeline(page, { messages: [userMessage(), assistantMessage(parts)] })
+
+    await expect(
+      page.locator('[data-timeline-part-ids="prt_01_read,prt_02_glob,prt_03_grep,prt_04_list"]'),
+    ).toBeVisible()
+    for (const id of [
+      "prt_webfetch",
+      "prt_websearch",
+      "prt_task",
+      "prt_bash",
+      "prt_edit",
+      "prt_write",
+      "prt_patch",
+      "prt_question",
+      "prt_skill",
+      "prt_custom",
+    ]) {
+      await expect(page.locator(`[data-timeline-part-id="${id}"]`).first(), id).toBeVisible()
+    }
+    await expect(page.locator('[data-timeline-part-id="prt_todo"]')).toHaveCount(0)
+  })
+
+  test("projects gaps, dividers, assistant parts, and errors together", async ({ page }) => {
+    const firstUser = userMessage(
+      [
+        userText("The user made the following comment regarding lines 4 through 8 of src/a.ts: Keep this stable", {
+          id: "prt_comment",
+          synthetic: true,
+          metadata: {
+            opencodeComment: {
+              path: "src/a.ts",
+              selection: { startLine: 4, startChar: 0, endLine: 8, endChar: 0 },
+              comment: "Keep this stable",
+            },
+          },
+        }),
+        userText("Continue after the comment", { id: "prt_visible_user" }),
+      ],
+      { summary: { diffs: Array.from({ length: 11 }, (_, index) => summaryDiff(index)) } },
+    )
+    const aborted = assistantMessage(
+      [
+        { id: "prt_before_abort", type: "text", text: "Before interruption" },
+        { id: "prt_compaction", type: "compaction", auto: true },
+      ],
+      {
+        id: "msg_1001_assistant_aborted",
+        error: { name: "MessageAbortedError", data: { message: "Stopped" } },
+      },
+    )
+    const failed = assistantMessage([{ id: "prt_after_abort", type: "text", text: "After interruption" }], {
+      id: "msg_1002_assistant_failed",
+      error: {
+        name: "APIError",
+        data: {
+          message: JSON.stringify({ error: { type: "provider_error", message: "Visible provider failure" } }),
+          isRetryable: false,
+        },
+      },
+      created: 1700000003000,
+    })
+    const nextUser = userMessage([userText("Second turn", { id: "prt_second_user" })], {
+      id: "msg_2000_second_user",
+      created: 1700000005000,
+    })
+    const nextAssistant = assistantMessage([{ id: "prt_second_text", type: "text", text: "Second response" }], {
+      id: "msg_2001_second_assistant",
+      parentID: "msg_2000_second_user",
+      created: 1700000006000,
+    })
+    const timeline = await setupTimeline(page, { messages: [firstUser, aborted, failed, nextUser, nextAssistant] })
+    await timeline.send(status("idle"), 100)
+    const scroller = page.locator(".scroll-view__viewport", { has: page.locator("[data-timeline-row]") })
+    await scroller.evaluate((element) => (element.scrollTop = 0))
+
+    await expect(page.locator('[data-timeline-row="TurnDivider"]')).toHaveCount(1)
+    await expect(page.getByText("Session compacted", { exact: true })).toBeVisible()
+    await expect(page.getByText("Visible provider failure")).toBeVisible()
+    await scroller.evaluate((element) => (element.scrollTop = element.scrollHeight))
+    await expect(page.locator('[data-timeline-row="TurnGap"]')).toBeVisible()
+  })
+
+  test("renders inline comments and historical diff summary overflow", async ({ page }) => {
+    const user = userMessage(
+      [
+        userText("The user made the following comment regarding lines 4 through 8 of src/a.ts: Keep this stable", {
+          id: "prt_comment_only",
+          synthetic: true,
+          metadata: {
+            opencodeComment: {
+              path: "src/a.ts",
+              selection: { startLine: 4, startChar: 0, endLine: 8, endChar: 0 },
+              comment: "Keep this stable",
+            },
+          },
+        }),
+        userText("Continue after the comment", { id: "prt_comment_visible" }),
+      ],
+      { summary: { diffs: Array.from({ length: 11 }, (_, index) => summaryDiff(index)) } },
+    )
+    const nextUser = userMessage(undefined, { id: "msg_2000_diff_next_user", created: 1700000010000 })
+    const nextAssistant = assistantMessage([], {
+      id: "msg_2001_diff_next_assistant",
+      parentID: "msg_2000_diff_next_user",
+      created: 1700000011000,
+    })
+    await setupTimeline(page, { messages: [user, assistantMessage(), nextUser, nextAssistant] })
+    const scroller = page.locator(".scroll-view__viewport", { has: page.locator("[data-timeline-row]") })
+    await scroller.evaluate((element) => (element.scrollTop = 0))
+
+    await expect(page.getByText("Keep this stable", { exact: true })).toBeVisible()
+    await expect(page.locator('[data-timeline-row="DiffSummary"]')).toBeVisible()
+    await expect(page.getByText(/show all/i)).toBeVisible()
+  })
+
+  test("renders interruption independently when the turn is not compacted", async ({ page }) => {
+    const user = userMessage()
+    const before = assistantMessage([{ id: "prt_before", type: "text", text: "Before" }], {
+      id: "msg_1001_before",
+      error: { name: "MessageAbortedError", data: { message: "Stopped" } },
+    })
+    const after = assistantMessage([{ id: "prt_after", type: "text", text: "After" }], {
+      id: "msg_1002_after",
+      created: 1700000003000,
+    })
+    await setupTimeline(page, { messages: [user, before, after] })
+
+    await expect(page.getByText("Interrupted", { exact: true })).toBeVisible()
+    const rows = await page
+      .locator('[data-timeline-row="AssistantPart"], [data-timeline-row="TurnDivider"]')
+      .evaluateAll((elements) => elements.map((element) => element.getAttribute("data-timeline-row")))
+    expect(rows).toEqual(["AssistantPart", "TurnDivider", "AssistantPart"])
+  })
+
+  test("renders user image, file attachment, file reference, and agent reference", async ({ page }) => {
+    const text = "Use @explore with @src/a.ts and inspect the attachments"
+    const parts: PartSeed<"user">[] = [
+      userText(text, { id: "prt_user_rich" }),
+      {
+        id: "prt_user_image",
+        type: "file",
+        mime: "image/png",
+        filename: "pixel.png",
+        url: "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNk+M9QDwADhgGAWjR9awAAAABJRU5ErkJggg==",
+      },
+      {
+        id: "prt_user_attachment",
+        type: "file",
+        mime: "application/json",
+        filename: "tsconfig.json",
+        url: "data:application/json;base64,e30=",
+      },
+      {
+        id: "prt_user_reference",
+        type: "file",
+        mime: "text/plain",
+        filename: "a.ts",
+        url: "src/a.ts",
+        source: { type: "file", path: "src/a.ts", text: { value: "@src/a.ts", start: 18, end: 27 } },
+      },
+      {
+        id: "prt_user_agent",
+        type: "agent",
+        name: "explore",
+        source: { value: "@explore", start: 4, end: 12 },
+      },
+    ]
+    await setupTimeline(page, { messages: [userMessage(parts), assistantMessage()] })
+
+    await expect(page.getByAltText("pixel.png")).toBeVisible()
+    await expect(page.getByText("tsconfig.json")).toBeVisible()
+    await expect(page.getByText("@src/a.ts", { exact: true })).toBeVisible()
+    await expect(page.getByText("@explore", { exact: true })).toBeVisible()
+  })
+})
+
+function editPart(id: string) {
+  return toolPart(
+    id,
+    "edit",
+    "completed",
+    { filePath: "src/a.ts" },
+    {
+      metadata: {
+        filediff: {
+          file: "src/a.ts",
+          additions: 1,
+          deletions: 1,
+          before: "export const value = 1\n",
+          after: "export const value = 2\n",
+        },
+      },
+    },
+  )
+}
+
+function patchPart(id: string) {
+  return toolPart(
+    id,
+    "apply_patch",
+    "completed",
+    { files: ["src/a.ts", "src/b.ts"] },
+    {
+      metadata: {
+        files: [
+          patchFile("src/a.ts", "update"),
+          patchFile("src/b.ts", "add"),
+          patchFile("src/old.ts", "delete"),
+          { ...patchFile("src/moved.ts", "move"), move: "src/new-place.ts" },
+        ],
+      },
+    },
+  )
+}
+
+function patchFile(filePath: string, type: "add" | "update" | "delete" | "move") {
+  return {
+    filePath,
+    relativePath: filePath,
+    type,
+    additions: type === "delete" ? 0 : 1,
+    deletions: type === "add" ? 0 : 1,
+    before: type === "add" ? undefined : "export const before = true\n",
+    after: type === "delete" ? undefined : "export const after = true\n",
+  }
+}
+
+function summaryDiff(index: number) {
+  return {
+    file: `src/diff-${index}.ts`,
+    additions: 1,
+    deletions: 1,
+    patch: `@@ -1 +1 @@\n-export const value = ${index}\n+export const value = ${index + 1}`,
+  }
+}

packages/app/e2e/regression/session-timeline-reasoning-projection.spec.ts

@@ -0,0 +1,93 @@
+import { expect, test } from "@playwright/test"
+import {
+  assistantMessage,
+  reasoningPart,
+  setupTimeline,
+  status,
+  textPart,
+  toolPart,
+  userMessage,
+} from "../performance/timeline-stability/fixture"
+
+const profiles = [
+  { name: "summaries off no reasoning", summaries: false, reasoning: "", other: false, thinking: true, body: false },
+  {
+    name: "summaries off reasoning heading",
+    summaries: false,
+    reasoning: "## Inspecting stability",
+    other: false,
+    thinking: true,
+    body: false,
+  },
+  {
+    name: "summaries off with visible tool",
+    summaries: false,
+    reasoning: "## Inspecting stability",
+    other: true,
+    thinking: true,
+    body: false,
+  },
+  { name: "summaries on no content", summaries: true, reasoning: "", other: false, thinking: true, body: false },
+  {
+    name: "summaries on blank reasoning",
+    summaries: true,
+    reasoning: "   ",
+    other: false,
+    thinking: true,
+    body: false,
+  },
+  {
+    name: "summaries on visible reasoning",
+    summaries: true,
+    reasoning: "## Inspecting stability",
+    other: false,
+    thinking: false,
+    body: true,
+  },
+  {
+    name: "summaries on visible tool no reasoning",
+    summaries: true,
+    reasoning: "",
+    other: true,
+    thinking: false,
+    body: false,
+  },
+] as const
+
+for (const profile of profiles) {
+  test(`projects busy reasoning profile ${profile.name}`, async ({ page }) => {
+    const reasoningID = `prt_reasoning_matrix_${profiles.indexOf(profile)}`
+    const parts = [
+      ...(profile.reasoning ? [reasoningPart(reasoningID, profile.reasoning)] : []),
+      ...(profile.other
+        ? [toolPart(`prt_reasoning_tool_${profiles.indexOf(profile)}`, "skill", "running", { name: "inspect" })]
+        : []),
+    ]
+    const timeline = await setupTimeline(page, {
+      messages: [userMessage(), assistantMessage(parts, { completed: false })],
+      settings: { showReasoningSummaries: profile.summaries },
+    })
+    await timeline.send(status("busy"), 150)
+
+    await expect(page.locator('[data-timeline-row="Thinking"]')).toHaveCount(profile.thinking ? 1 : 0)
+    await expect(page.locator(`[data-timeline-part-id="${reasoningID}"]`)).toHaveCount(profile.body ? 1 : 0)
+    if (!profile.summaries && profile.reasoning.trim()) {
+      await expect(page.getByText("Inspecting stability", { exact: true })).toBeVisible()
+    }
+  })
+}
+
+test("does not infer reasoning visibility from provider identity", async ({ page }) => {
+  const timeline = await setupTimeline(page, {
+    messages: [
+      userMessage(),
+      assistantMessage([textPart("prt_provider_text", "No reasoning payload")], { completed: false }),
+    ],
+    settings: { showReasoningSummaries: true },
+  })
+  await timeline.send(status("busy"), 150)
+
+  await expect(page.locator('[data-timeline-row="Thinking"]')).toHaveCount(0)
+  await expect(page.locator('[data-timeline-part-id*="reasoning"]')).toHaveCount(0)
+  await expect(page.locator('[data-timeline-part-id="prt_provider_text"]')).toBeVisible()
+})

packages/app/e2e/regression/session-timeline-reducer-projection.spec.ts

@@ -0,0 +1,43 @@
+import { expect, test } from "@playwright/test"
+import {
+  assistantMessage,
+  completedAssistantInfo,
+  messageUpdated,
+  partUpdated,
+  setupTimeline,
+  shell,
+  status,
+  textPart,
+  toolPart,
+  userMessage,
+} from "../performance/timeline-stability/fixture"
+
+test("groups singleton and separated context operations at correct boundaries", async ({ page }) => {
+  const parts = [
+    toolPart("prt_boundary_01_read", "read", "completed", { filePath: "src/a.ts" }),
+    textPart("prt_boundary_02_text", "Boundary text"),
+    toolPart("prt_boundary_03_glob", "glob", "completed", { path: ".", pattern: "**/*.ts" }),
+    toolPart("prt_boundary_04_grep", "grep", "completed", { path: ".", pattern: "stable" }),
+    shell("prt_boundary_05_shell", "completed", "done"),
+    toolPart("prt_boundary_06_list", "list", "completed", { path: "src" }),
+  ]
+  await setupTimeline(page, { messages: [userMessage(), assistantMessage(parts)] })
+
+  await expect(page.locator('[data-timeline-part-ids="prt_boundary_01_read"]')).toBeVisible()
+  await expect(page.locator('[data-timeline-part-ids="prt_boundary_03_glob,prt_boundary_04_grep"]')).toBeVisible()
+  await expect(page.locator('[data-timeline-part-ids="prt_boundary_06_list"]')).toBeVisible()
+  await expect(page.locator('[data-timeline-row="AssistantPart"]')).toHaveCount(5)
+})
+
+test("reducer-hardening: converges when idle arrives before final part and message completion", async ({ page }) => {
+  const textID = "prt_event_order_text"
+  const assistant = assistantMessage([textPart(textID, "Partial")], { completed: false })
+  const timeline = await setupTimeline(page, { messages: [userMessage(), assistant] })
+  await timeline.send(status("busy"), 100)
+  await timeline.send(status("idle"), 100)
+  await timeline.send(partUpdated(textPart(textID, "Final after early idle")), 120)
+  await timeline.send(messageUpdated(completedAssistantInfo(assistant.info)), 250)
+
+  await expect(page.locator('[data-timeline-row="Thinking"]')).toHaveCount(0)
+  await expect(page.locator(`[data-timeline-part-id="${textID}"]`)).toContainText("Final after early idle")
+})

packages/app/e2e/regression/session-timeline-shell-outline.spec.ts

@@ -0,0 +1,228 @@
+import { expect, test, type Locator, type Page } from "@playwright/test"
+import {
+  assistantMessage,
+  setupTimeline,
+  shell,
+  textPart,
+  toolPart,
+  userMessage,
+} from "../performance/timeline-stability/fixture"
+
+for (const deviceScaleFactor of [1.25, 1.5]) {
+  test(`keeps the shell outline inside a fractionally short virtual row at ${deviceScaleFactor}x`, async ({ page }) => {
+    const shellID = "prt_shell_outline"
+    const timeline = await setupTimeline(page, {
+      messages: [userMessage(), assistantMessage([shell(shellID, "completed", "shell output")])],
+      settings: { newLayoutDesigns: true, shellToolPartsExpanded: true },
+      reducedMotion: true,
+      deviceScaleFactor,
+    })
+    const part = page.locator(`[data-timeline-part-id="${shellID}"]`)
+    const output = part.locator('[data-component="bash-output"]')
+    const row = page.locator("[data-timeline-key]", { has: part })
+    await expect(output).toBeVisible()
+    await timeline.settle()
+
+    const geometry = await row.evaluate((element) => {
+      const output = element.querySelector<HTMLElement>('[data-component="bash-output"]')
+      if (!output) throw new Error("Shell output is unavailable")
+      const rowRect = element.getBoundingClientRect()
+      const outputRect = output.getBoundingClientRect()
+      // Match a rounded-down measurement at a fractional device-pixel phase.
+      element.style.height = `${outputRect.bottom - rowRect.top - 0.49}px`
+      element.style.transform = "translateY(0.25px)"
+      output.style.setProperty("--v2-border-border-base", "rgb(255, 0, 255)")
+      output.style.setProperty("background", "rgb(0, 0, 0)", "important")
+      const style = getComputedStyle(output)
+      return {
+        outputWidth: outputRect.width,
+        outputHeight: outputRect.height,
+        borderColor: style.borderTopColor,
+        boxShadow: style.boxShadow,
+        clipMargin: getComputedStyle(element).overflowClipMargin,
+      }
+    })
+    await timeline.settle()
+
+    const clipped = await row.evaluate((element) => {
+      const output = element.querySelector<HTMLElement>('[data-component="bash-output"]')!
+      return output.getBoundingClientRect().bottom - element.getBoundingClientRect().bottom
+    })
+    expect(clipped).toBeCloseTo(0.49, 1)
+
+    expect(await page.evaluate(() => devicePixelRatio)).toBe(deviceScaleFactor)
+    const edges = await captureCardEdges(page, output)
+
+    expect(edges.box.width).toBeCloseTo(geometry.outputWidth, 2)
+    expect(edges.box.height).toBeCloseTo(geometry.outputHeight, 2)
+    expect(geometry.borderColor).toBe("rgb(255, 0, 255)")
+    expect(geometry.boxShadow).toBe("none")
+    expect(geometry.clipMargin).toBe("0.5px")
+    expect(edges.magenta.top).toBeGreaterThan(0.75)
+    expect(edges.magenta.bottom).toBeGreaterThan(0.75)
+    expect(edges.magenta.vertical).toBeGreaterThanOrEqual(2)
+  })
+}
+
+test("keeps the patch card inside a fractionally short virtual row", async ({ page }) => {
+  const patchID = "prt_patch_outline"
+  const file = {
+    filePath: "src/outline.ts",
+    relativePath: "src/outline.ts",
+    type: "update",
+    additions: 1,
+    deletions: 1,
+    before: "const outline = false\n",
+    after: "const outline = true\n",
+  }
+  const timeline = await setupTimeline(page, {
+    messages: [
+      userMessage(),
+      assistantMessage([
+        toolPart(patchID, "apply_patch", "completed", { files: [file.filePath] }, { metadata: { files: [file] } }),
+      ]),
+    ],
+    settings: { editToolPartsExpanded: true, newLayoutDesigns: true },
+    reducedMotion: true,
+  })
+  const part = page.locator(`[data-timeline-part-id="${patchID}"]`)
+  const card = part.locator('[data-component="accordion"][data-scope="apply-patch"]')
+  const row = page.locator("[data-timeline-key]", { has: part })
+  await expect(card).toBeVisible()
+  await timeline.settle()
+
+  const geometry = await row.evaluate((element) => {
+    const card = element.querySelector<HTMLElement>('[data-component="accordion"][data-scope="apply-patch"]')
+    if (!card) throw new Error("Patch card is unavailable")
+    const rowRect = element.getBoundingClientRect()
+    const cardRect = card.getBoundingClientRect()
+    element.style.height = `${cardRect.bottom - rowRect.top - 0.49}px`
+    const clipMargin = getComputedStyle(element).overflowClipMargin
+    const bottom = element.getBoundingClientRect().bottom
+    return {
+      overflow: card.getBoundingClientRect().bottom - bottom,
+      paintOverflow: card.getBoundingClientRect().bottom - bottom - Number.parseFloat(clipMargin),
+      clipMargin,
+      cardWidth: cardRect.width,
+      cardHeight: cardRect.height,
+    }
+  })
+  await timeline.settle()
+
+  expect(geometry.overflow).toBeCloseTo(0.49, 1)
+  expect(geometry.paintOverflow).toBeLessThanOrEqual(0)
+  const edges = await captureCardEdges(page, card)
+  expect(edges.box.width).toBeCloseTo(geometry.cardWidth, 2)
+  expect(edges.box.height).toBeCloseTo(geometry.cardHeight, 2)
+  expect(edges.luminance.top).toBeLessThan(245)
+  expect(edges.luminance.bottom).toBeLessThan(245)
+  expect(Math.abs(edges.luminance.bottom - edges.luminance.top)).toBeLessThan(10)
+  expect(geometry.clipMargin).toBe("0.5px")
+})
+
+test("allows paint rounding for every framed row but not fixed turn gaps", async ({ page }) => {
+  const secondUserID = "msg_outline_second_user"
+  await setupTimeline(page, {
+    messages: [
+      userMessage(undefined, {
+        summary: {
+          diffs: [
+            {
+              file: "src/summary.ts",
+              additions: 1,
+              deletions: 1,
+              patch: "@@ -1 +1 @@\n-export const value = 1\n+export const value = 2",
+            },
+          ],
+        },
+      }),
+      assistantMessage([textPart("prt_outline_text", "Assistant text")]),
+      userMessage(undefined, { id: secondUserID, created: 1700000010000 }),
+      assistantMessage([], {
+        id: "msg_outline_second_assistant",
+        parentID: secondUserID,
+        created: 1700000011000,
+      }),
+    ],
+  })
+  await expect(page.locator('[data-timeline-row="DiffSummary"]')).toBeVisible()
+  await expect(page.locator('[data-timeline-row="TurnGap"]')).toBeVisible()
+
+  const rows = await page.locator("[data-timeline-key]").evaluateAll((elements) =>
+    elements.map((element) => ({
+      tag: element.querySelector<HTMLElement>("[data-timeline-row]")?.dataset.timelineRow,
+      clipMargin: getComputedStyle(element).overflowClipMargin,
+    })),
+  )
+  expect(rows.filter((row) => row.tag !== "TurnGap").every((row) => row.clipMargin === "0.5px")).toBe(true)
+  expect(rows.filter((row) => row.tag === "TurnGap")).toEqual([{ tag: "TurnGap", clipMargin: "0px" }])
+})
+
+async function captureCardEdges(page: Page, card: Locator) {
+  const box = await card.boundingBox()
+  if (!box) throw new Error("Tool card bounds are unavailable")
+  const viewport = page.viewportSize()
+  if (!viewport) throw new Error("Viewport bounds are unavailable")
+  const screenshot = await page.screenshot()
+  return page.evaluate(
+    async ({ source, box, viewport }) => {
+      const image = new Image()
+      image.src = source
+      await image.decode()
+      const canvas = document.createElement("canvas")
+      canvas.width = image.naturalWidth
+      canvas.height = image.naturalHeight
+      const context = canvas.getContext("2d")
+      if (!context) throw new Error("2D canvas is unavailable")
+      context.drawImage(image, 0, 0)
+      const scale = {
+        x: image.naturalWidth / viewport.width,
+        y: image.naturalHeight / viewport.height,
+      }
+      const rows = (candidates: number[]) => {
+        const left = Math.floor((box.x + 8) * scale.x)
+        const width = Math.floor((box.width - 16) * scale.x)
+        return candidates.map((row) => {
+          const pixels = context.getImageData(left, row, width, 1).data
+          const indexes = Array.from({ length: width }, (_, index) => index * 4)
+          return {
+            luminance:
+              indexes
+                .map((index) => (pixels[index]! + pixels[index + 1]! + pixels[index + 2]!) / 3)
+                .reduce((sum, value) => sum + value, 0) / width,
+            magenta:
+              indexes.filter((index) => pixels[index]! > 200 && pixels[index + 1]! < 180 && pixels[index + 2]! > 200)
+                .length / width,
+          }
+        })
+      }
+      const pixels = context.getImageData(0, 0, image.naturalWidth, image.naturalHeight).data
+      const columns = new Uint32Array(image.naturalWidth)
+      for (let index = 0; index < pixels.length; index += 4) {
+        if (pixels[index]! <= 200 || pixels[index + 1]! >= 180 || pixels[index + 2]! <= 200) continue
+        columns[(index / 4) % image.naturalWidth] = columns[(index / 4) % image.naturalWidth]! + 1
+      }
+      const top = box.y * scale.y
+      const bottom = (box.y + box.height) * scale.y
+      const topRows = rows([Math.floor(top) - 1, Math.floor(top), Math.ceil(top)])
+      const bottomRows = rows([Math.floor(bottom) - 2, Math.floor(bottom) - 1, Math.ceil(bottom) - 1])
+      return {
+        box,
+        luminance: {
+          top: Math.min(...topRows.map((row) => row.luminance)),
+          bottom: rows([Math.ceil(bottom) - 1])[0]!.luminance,
+        },
+        magenta: {
+          top: Math.max(...topRows.map((row) => row.magenta)),
+          bottom: Math.max(...bottomRows.map((row) => row.magenta)),
+          vertical: Array.from(columns).filter((count) => count > box.height * scale.y * 0.75).length,
+        },
+      }
+    },
+    {
+      source: `data:image/png;base64,${screenshot.toString("base64")}`,
+      viewport,
+      box,
+    },
+  )
+}

packages/app/e2e/regression/session-timeline-tool-projection.spec.ts

@@ -0,0 +1,99 @@
+import { expect, test } from "@playwright/test"
+import {
+  assistantMessage,
+  partUpdated,
+  setupTimeline,
+  toolPart,
+  userMessage,
+} from "../performance/timeline-stability/fixture"
+
+test("renders every tool error outcome without leaking hidden tools", async ({ page }) => {
+  const ordinary = ["bash", "edit", "write", "apply_patch", "webfetch", "websearch", "task", "skill", "mcp_probe"]
+  const parts = ordinary.map((tool, index) =>
+    toolPart(`prt_error_${index}`, tool, "error", errorInput(tool), { error: `${tool} failed visibly` }),
+  )
+  parts.push(
+    toolPart("prt_question_dismissed", "question", "error", questionInput(), {
+      error: "The user dismissed this question",
+    }),
+    toolPart("prt_question_error", "question", "error", questionInput(), { error: "Question transport failed" }),
+    toolPart("prt_todo_error", "todowrite", "error", { todos: [] }, { error: "Hidden todo failure" }),
+  )
+  await setupTimeline(page, { messages: [userMessage(), assistantMessage(parts)] })
+
+  await expect(page.locator('[data-kind="tool-error-card"]')).toHaveCount(ordinary.length + 1)
+  await expect(page.getByText(/dismissed/i)).toBeVisible()
+  await expect(page.locator('[data-timeline-part-id="prt_todo_error"]')).toHaveCount(0)
+  for (let index = 0; index < ordinary.length; index++) {
+    await expect(page.locator(`[data-timeline-part-id="prt_error_${index}"]`)).toBeVisible()
+  }
+})
+
+test("transitions shell and question through running error outcomes", async ({ page }) => {
+  const shellID = "prt_transition_error_shell"
+  const questionID = "prt_transition_error_question"
+  const timeline = await setupTimeline(page, {
+    messages: [
+      userMessage(),
+      assistantMessage(
+        [
+          toolPart(shellID, "bash", "pending", { command: "exit 1" }),
+          toolPart(questionID, "question", "pending", questionInput()),
+        ],
+        { completed: false },
+      ),
+    ],
+  })
+  await timeline.waitForPart(shellID)
+  await expect(page.locator(`[data-timeline-part-id="${questionID}"]`)).toHaveCount(0)
+  await timeline.send(partUpdated(toolPart(shellID, "bash", "running", { command: "exit 1" })), 120)
+  await timeline.send(partUpdated(toolPart(questionID, "question", "running", questionInput())), 180)
+  await expect(page.locator(`[data-timeline-part-id="${questionID}"]`)).toHaveCount(0)
+  await timeline.send(
+    partUpdated(toolPart(shellID, "bash", "error", { command: "exit 1" }, { error: "Command exited 1" })),
+    180,
+  )
+  await timeline.send(
+    partUpdated(
+      toolPart(questionID, "question", "error", questionInput(), { error: "The user dismissed this question" }),
+    ),
+    250,
+  )
+
+  await expect(page.locator(`[data-timeline-part-id="${shellID}"] [data-kind="tool-error-card"]`)).toBeVisible()
+  await expect(page.locator(`[data-timeline-part-id="${questionID}"]`)).toContainText(/dismissed/i)
+})
+
+test("labels all web search provider variants", async ({ page }) => {
+  const parts = [
+    toolPart(
+      "prt_search_parallel",
+      "websearch",
+      "completed",
+      { query: "parallel" },
+      { metadata: { provider: "parallel" } },
+    ),
+    toolPart("prt_search_exa", "websearch", "completed", { query: "exa" }, { metadata: { provider: "exa" } }),
+    toolPart("prt_search_generic", "websearch", "completed", { query: "generic" }),
+  ]
+  await setupTimeline(page, { messages: [userMessage(), assistantMessage(parts)] })
+
+  await expect(page.getByRole("button", { name: /Parallel Web Search/ })).toBeVisible()
+  await expect(page.getByRole("button", { name: /Exa Web Search/ })).toBeVisible()
+  await expect(page.getByRole("button", { name: /^Web Search/ })).toBeVisible()
+})
+
+function questionInput() {
+  return { questions: [{ header: "Stability", question: "Keep it stable?", options: [] }] }
+}
+
+function errorInput(tool: string) {
+  if (tool === "bash") return { command: "exit 1" }
+  if (["edit", "write"].includes(tool)) return { filePath: "src/error.ts", content: "" }
+  if (tool === "apply_patch") return { files: ["src/error.ts"] }
+  if (tool === "webfetch") return { url: "https://example.com" }
+  if (tool === "websearch") return { query: "failure" }
+  if (tool === "task") return { description: "Fail task", subagent_type: "explore" }
+  if (tool === "skill") return { name: "failure" }
+  return { target: "failure" }
+}

packages/app/e2e/regression/session-timeline-tool-state.spec.ts

@@ -0,0 +1,77 @@
+import { expect, test } from "@playwright/test"
+import {
+  assistantMessage,
+  partUpdated,
+  setupTimeline,
+  toolPart,
+  userMessage,
+} from "../performance/timeline-stability/fixture"
+
+test("updates expanded web search links without resetting expansion", async ({ page }) => {
+  const searchID = "prt_websearch_mutation"
+  const input = { query: "timeline stability" }
+  const timeline = await setupTimeline(page, {
+    messages: [
+      userMessage(),
+      assistantMessage([toolPart(searchID, "websearch", "completed", input, { output: "https://example.com/one" })]),
+    ],
+  })
+  const wrapper = page.locator(`[data-timeline-part-id="${searchID}"]`)
+  const trigger = wrapper.locator('[data-slot="collapsible-trigger"]')
+  await trigger.click()
+  await expect(trigger).toHaveAttribute("aria-expanded", "true")
+  await timeline.send(
+    partUpdated(
+      toolPart(searchID, "websearch", "completed", input, {
+        output: "https://example.com/one\nhttps://example.com/two",
+      }),
+    ),
+    300,
+  )
+  await expect(trigger).toHaveAttribute("aria-expanded", "true")
+  await expect(wrapper.locator('a[href="https://example.com/two"]')).toBeVisible()
+})
+
+test("preserves an expanded tool error card across duplicate delivery", async ({ page }) => {
+  const toolID = "prt_duplicate_error"
+  const failed = toolPart(toolID, "bash", "error", { command: "exit 1" }, { error: "Command failed visibly" })
+  const timeline = await setupTimeline(page, { messages: [userMessage(), assistantMessage([failed])] })
+  const wrapper = page.locator(`[data-timeline-part-id="${toolID}"]`)
+  const trigger = wrapper.locator('[data-slot="collapsible-trigger"]')
+  await trigger.click()
+  await expect(trigger).toHaveAttribute("aria-expanded", "true")
+  await timeline.send(partUpdated(failed), 150)
+  await timeline.send(partUpdated(failed), 250)
+  await expect(trigger).toHaveAttribute("aria-expanded", "true")
+  await expect(wrapper).toContainText("Command failed visibly")
+})
+
+test("renders multiple question answers and preserves open state on answer updates", async ({ page }) => {
+  const questionID = "prt_multi_question"
+  const input = {
+    questions: [
+      { header: "First", question: "First choice?", options: [] },
+      { header: "Second", question: "Second choice?", options: [], multiple: true },
+    ],
+  }
+  const timeline = await setupTimeline(page, {
+    messages: [
+      userMessage(),
+      assistantMessage([
+        toolPart(questionID, "question", "completed", input, { metadata: { answers: [["A"], ["B", "C"]] } }),
+      ]),
+    ],
+  })
+  const wrapper = page.locator(`[data-timeline-part-id="${questionID}"]`)
+  const trigger = wrapper.locator('[data-slot="collapsible-trigger"]')
+  await expect(trigger).toHaveAttribute("aria-expanded", "true")
+  await timeline.send(
+    partUpdated(
+      toolPart(questionID, "question", "completed", input, { metadata: { answers: [["Updated"], ["B", "C"]] } }),
+    ),
+    300,
+  )
+  await expect(trigger).toHaveAttribute("aria-expanded", "true")
+  await expect(wrapper).toContainText("Updated")
+  await expect(wrapper).toContainText("B, C")
+})

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

@@ -0,0 +1,154 @@
+import { expect, test, type Page } from "@playwright/test"
+import {
+  assistantMessage,
+  partUpdated,
+  setupTimeline,
+  textPart,
+  userMessage,
+} from "../performance/timeline-stability/fixture"
+
+test("keeps one connection open while delivering multiple events", async ({ page }) => {
+  const timeline = await setupTimeline(page)
+
+  const first = await timeline.transport.send(partUpdated(textPart("prt_transport_first", "first event")))
+  const second = await timeline.transport.send(partUpdated(textPart("prt_transport_second", "second event")))
+
+  await timeline.waitForPart("prt_transport_first")
+  await timeline.waitForPart("prt_transport_second")
+  expect(first.connectionID).toBe(second.connectionID)
+  await expect.poll(async () => (await timeline.transport.connections()).length).toBe(1)
+  expect(await timeline.transport.acknowledgements()).toHaveLength(2)
+})
+
+test("delivers a burst from one stream chunk", async ({ page }) => {
+  const timeline = await setupTimeline(page)
+  const acknowledgements = await timeline.transport.burst([
+    partUpdated(textPart("prt_transport_burst_a", "burst a")),
+    partUpdated(textPart("prt_transport_burst_b", "burst b")),
+  ])
+
+  await timeline.waitForPart("prt_transport_burst_a")
+  await timeline.waitForPart("prt_transport_burst_b")
+  expect(acknowledgements.map((item) => item.chunkCount)).toEqual([1, 1])
+  expect(new Set(acknowledgements.map((item) => item.deliveryID)).size).toBe(2)
+})
+
+test("parses split JSON and a split multibyte code point", async ({ page }) => {
+  const timeline = await setupTimeline(page)
+  const payload = partUpdated(textPart("prt_transport_split", "split snowman \u2603\u2603\u2603"))
+  const encoded = new TextEncoder().encode(`data: ${JSON.stringify(payload)}\n\n`)
+  const snowman = new TextEncoder().encode("\u2603")[0]!
+  const multibyte = encoded.indexOf(snowman)
+
+  const acknowledgement = await timeline.transport.split(payload, [9, multibyte + 1, multibyte + 2])
+
+  await timeline.waitForPart("prt_transport_split")
+  await expect(page.locator('[data-timeline-part-id="prt_transport_split"]')).toContainText(
+    "split snowman \u2603\u2603\u2603",
+  )
+  expect(acknowledgement.chunkCount).toBe(4)
+})
+
+test("delivers server heartbeat without mutating the timeline", async ({ page }) => {
+  const sentinelID = "prt_transport_heartbeat_sentinel"
+  const timeline = await setupTimeline(page, {
+    messages: [userMessage(), assistantMessage([textPart("prt_transport_steady", "steady")])],
+  })
+  await timeline.waitForPart("prt_transport_steady")
+  const before = await stableTimelineRows(page)
+
+  await timeline.transport.writeRaw(": heartbeat\n\n")
+  await timeline.transport.send(partUpdated(textPart(sentinelID, "heartbeat processed")))
+  await timeline.waitForPart(sentinelID)
+
+  await expect
+    .poll(async () => {
+      const rows = await timelineRows(page)
+      return rows.filter((row) => before.some((item) => item.key === row.key))
+    })
+    .toEqual(before)
+  await expect.poll(async () => (await timeline.transport.connections()).length).toBe(1)
+})
+
+test("reconnects after a clean close", async ({ page }) => {
+  const timeline = await setupTimeline(page)
+  const first = await timeline.transport.waitForConnection()
+
+  await timeline.transport.close()
+  const second = await timeline.transport.waitForConnection({ after: first.id })
+  await timeline.transport.send(partUpdated(textPart("prt_transport_close", "after close")))
+
+  await timeline.waitForPart("prt_transport_close")
+  expect(second.id).toBeGreaterThan(first.id)
+  expect((await timeline.transport.connections())[0]?.endedBy).toBe("close")
+})
+
+test("reconnects after a stream error", async ({ page }) => {
+  const timeline = await setupTimeline(page)
+  const first = await timeline.transport.waitForConnection()
+
+  await timeline.transport.error("contract failure")
+  const second = await timeline.transport.waitForConnection({ after: first.id })
+  await timeline.transport.send(partUpdated(textPart("prt_transport_error", "after error")))
+
+  await timeline.waitForPart("prt_transport_error")
+  await expect.poll(async () => (await timeline.transport.connections()).length).toBe(2)
+  expect(second.id).toBeGreaterThan(first.id)
+  expect((await timeline.transport.connections())[0]?.endedBy).toBe("error")
+})
+
+test("does not request replay when reconnecting the volatile V2 event stream", async ({ page }) => {
+  const timeline = await setupTimeline(page, { protocol: "v2" })
+  const first = await timeline.transport.send(partUpdated(textPart("prt_transport_id", "event with id")), {
+    id: "timeline-event-7",
+  })
+  await timeline.waitForPart("prt_transport_id")
+
+  await timeline.transport.error("retry with event id")
+  const connection = await timeline.transport.waitForConnection({ after: first.connectionID })
+
+  expect(first.eventID).toBe("timeline-event-7")
+  expect(connection.headers["last-event-id"]).toBeUndefined()
+})
+
+test("passes through non-event fetches", async ({ page }) => {
+  const timeline = await setupTimeline(page)
+
+  const health = await page.evaluate(async () => {
+    const response = await fetch("/global/health")
+    return response.json()
+  })
+
+  expect(health).toEqual({ healthy: true })
+  await expect.poll(async () => (await timeline.transport.connections()).length).toBe(1)
+})
+
+async function stableTimelineRows(page: Page) {
+  let previous: Awaited<ReturnType<typeof timelineRows>> | undefined
+  let stable = 0
+  await expect
+    .poll(
+      async () => {
+        const next = await timelineRows(page)
+        stable = JSON.stringify(next) === JSON.stringify(previous) ? stable + 1 : 0
+        previous = next
+        return stable
+      },
+      { intervals: [50, 50, 100] },
+    )
+    .toBeGreaterThanOrEqual(2)
+  return previous!
+}
+
+function timelineRows(page: Page) {
+  return page.locator("[data-timeline-key]").evaluateAll((elements) =>
+    elements.map((element) => ({
+      key: element.getAttribute("data-timeline-key"),
+      row: element.querySelector("[data-timeline-row]")?.getAttribute("data-timeline-row"),
+      parts: Array.from(element.querySelectorAll("[data-timeline-part-id]"), (part) =>
+        part.getAttribute("data-timeline-part-id"),
+      ),
+      text: element.textContent,
+    })),
+  )
+}

packages/app/e2e/regression/session-todo-dock-navigation.spec.ts

@@ -0,0 +1,190 @@
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { expect, test, type Page } from "@playwright/test"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectSessionTitle } from "../utils/waits"
+
+const directory = "C:/OpenCode/TodoDockNavigation"
+const projectID = "proj_todo_dock_navigation"
+const sourceID = "ses_todo_dock_source"
+const otherID = "ses_todo_dock_other"
+const sourceTitle = "Todo dock animation"
+const otherTitle = "Separate session"
+
+const activeTodos = [
+  { id: "todo-1", content: "Receive todos in the active session", status: "completed", priority: "high" },
+  { id: "todo-2", content: "Keep the dock visible across tabs", status: "completed", priority: "high" },
+  { id: "todo-3", content: "Close after the final todo", status: "in_progress", priority: "high" },
+]
+
+type EventPayload = {
+  directory: string
+  payload: Record<string, unknown>
+}
+
+test.use({ viewport: { width: 1440, height: 900 }, reducedMotion: "no-preference" })
+
+test("animates todo lifecycle without replaying it across session tabs", async ({ page }) => {
+  test.setTimeout(90_000)
+  const events: EventPayload[] = []
+  const todos: Record<string, typeof activeTodos> = { [sourceID]: [], [otherID]: [] }
+  const sessionStatus: Record<string, { type: "busy" | "idle" }> = {}
+
+  await mockOpenCodeServer(page, {
+    directory,
+    project: {
+      id: projectID,
+      worktree: directory,
+      vcs: "git",
+      name: "todo-dock-navigation",
+      time: { created: 1700000000000, updated: 1700000000000 },
+      sandboxes: [],
+    },
+    provider: {
+      all: [
+        {
+          id: "opencode",
+          name: "OpenCode",
+          models: {
+            "claude-opus-4-6": {
+              id: "claude-opus-4-6",
+              name: "Claude Opus 4.6",
+              limit: { context: 200_000 },
+            },
+          },
+        },
+      ],
+      connected: ["opencode"],
+      default: { providerID: "opencode", modelID: "claude-opus-4-6" },
+    },
+    sessions: [session(sourceID, sourceTitle, 1700000000000), session(otherID, otherTitle, 1700000001000)],
+    sessionStatus: { [sourceID]: { type: "busy" } },
+    pageMessages: () => ({ items: [] }),
+    events: () => events.splice(0, 1),
+    eventRetry: 16,
+    sessionStatus: () => sessionStatus,
+    todos: (sessionID) => todos[sessionID] ?? [],
+  })
+  await configurePage(page)
+
+  await page.goto(sessionHref(sourceID))
+  await expectSessionTitle(page, sourceTitle)
+  const dock = page.locator('[data-component="session-todo-dock"]')
+  await expect(dock).toHaveCount(0)
+
+  sessionStatus[sourceID] = { type: "busy" }
+  events.push(statusEvent(sourceID, "busy"))
+  await expect(page.getByRole("button", { name: "Stop" })).toBeVisible()
+
+  await page.waitForTimeout(700)
+  const opening = sampleDock(page, 1_000)
+  todos[sourceID] = activeTodos
+  events.push(todoEvent(sourceID, activeTodos))
+  await expect(dock).toBeVisible()
+  await expect(dock.locator('[data-state="in_progress"]')).toHaveCount(1)
+  expect((await opening).some((sample) => sample.opacity > 0.05 && sample.opacity < 0.95)).toBe(true)
+
+  await switchSession(page, otherID, otherTitle)
+  await expect(dock).toHaveCount(0)
+
+  const returningOpen = sampleDock(page, 700)
+  await switchSession(page, sourceID, sourceTitle)
+  const openSamples = (await returningOpen).filter((sample) => sample.present)
+  expect(openSamples.length).toBeGreaterThan(0)
+  expect(openSamples[0]!.opacity).toBeGreaterThan(0.98)
+  expect(openSamples[0]!.height).toBeGreaterThan(70)
+  await expect(dock.locator('[data-state="in_progress"]')).toHaveCount(1)
+
+  const completedTodos = activeTodos.map((todo) => ({ ...todo, status: "completed" }))
+  const closing = sampleDock(page, 1_000)
+  todos[sourceID] = completedTodos
+  events.push(todoEvent(sourceID, completedTodos))
+  await expect(dock).toHaveCount(0)
+  expect((await closing).some((sample) => sample.opacity > 0.05 && sample.opacity < 0.95)).toBe(true)
+  todos[sourceID] = []
+  events.push(todoEvent(sourceID, []))
+
+  await switchSession(page, otherID, otherTitle)
+  const returningEmpty = sampleDock(page, 700)
+  await switchSession(page, sourceID, sourceTitle)
+  await expect(dock).toHaveCount(0)
+  expect((await returningEmpty).every((sample) => !sample.present)).toBe(true)
+})
+
+function session(id: string, title: string, created: number) {
+  return {
+    id,
+    slug: id,
+    projectID,
+    directory,
+    title,
+    version: "dev",
+    time: { created, updated: created },
+  }
+}
+
+function statusEvent(sessionID: string, type: "busy" | "idle"): EventPayload {
+  return {
+    directory,
+    payload: { type: "session.status", properties: { sessionID, status: { type } } },
+  }
+}
+
+function todoEvent(sessionID: string, next: typeof activeTodos): EventPayload {
+  return {
+    directory,
+    payload: { type: "todo.updated", properties: { sessionID, todos: next } },
+  }
+}
+
+async function configurePage(page: Page) {
+  const server = `http://${process.env.PLAYWRIGHT_SERVER_HOST ?? "127.0.0.1"}:${process.env.PLAYWRIGHT_SERVER_PORT ?? "4096"}`
+  await page.addInitScript(
+    ({ directory, dirBase64, server, sessionIDs }) => {
+      localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: true } }))
+      localStorage.setItem(
+        "opencode.global.dat:server",
+        JSON.stringify({
+          projects: { local: [{ worktree: directory, expanded: true }] },
+          lastProject: { local: directory },
+        }),
+      )
+      localStorage.setItem(
+        "opencode.window.browser.dat:tabs",
+        JSON.stringify(sessionIDs.map((sessionId) => ({ type: "session", server, dirBase64, sessionId }))),
+      )
+    },
+    { directory, dirBase64: base64Encode(directory), server, sessionIDs: [sourceID, otherID] },
+  )
+}
+
+function sessionHref(sessionID: string) {
+  const server = `http://${process.env.PLAYWRIGHT_SERVER_HOST ?? "127.0.0.1"}:${process.env.PLAYWRIGHT_SERVER_PORT ?? "4096"}`
+  return `/server/${base64Encode(server)}/session/${sessionID}`
+}
+
+async function switchSession(page: Page, sessionID: string, title: string) {
+  const href = sessionHref(sessionID)
+  const tab = page.locator(`[data-slot="titlebar-tabs"] a[href="${href}"]`).first()
+  await expect(tab).toBeVisible()
+  await tab.click()
+  await expectSessionTitle(page, title)
+}
+
+function sampleDock(page: Page, duration: number) {
+  return page.evaluate(async (duration) => {
+    const samples: { present: boolean; height: number; opacity: number }[] = []
+    const start = performance.now()
+    while (performance.now() - start < duration) {
+      const dock = document.querySelector<HTMLElement>('[data-component="session-todo-dock"]')
+      const clip = dock?.parentElement?.parentElement
+      const label = dock?.querySelector<HTMLElement>('[data-action="session-todo-toggle"] span[aria-label]')
+      samples.push({
+        present: !!dock,
+        height: clip?.getBoundingClientRect().height ?? 0,
+        opacity: label ? Number.parseFloat(getComputedStyle(label).opacity) : 0,
+      })
+      await new Promise(requestAnimationFrame)
+    }
+    return samples
+  }, duration)
+}

packages/app/e2e/regression/subagent-child-navigation.spec.ts

@@ -0,0 +1,203 @@
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { expect, test, type Page } from "@playwright/test"
+import { currentSession, mockOpenCodeServer } from "../utils/mock-server"
+import { expectSessionTitle } from "../utils/waits"
+
+const directory = "C:/OpenCode/SubagentNavigation"
+const projectID = "proj_subagent_navigation"
+const parentID = "ses_subagent_parent"
+const childID = "ses_subagent_child"
+const parentTitle = "Parent session"
+const childTitle = "Subagent child session"
+// Child session pages derive their heading from the task part that spawned them.
+const taskDescription = "Inspect child navigation"
+
+type EventPayload = { directory: string; payload: Record<string, unknown> }
+
+test.use({ viewport: { width: 1440, height: 900 } })
+
+test("navigates to a subagent child session missing from the session list", async ({ page }) => {
+  await setup(page)
+  await openChildFromParent(page)
+
+  await expectSessionTitle(page, taskDescription)
+  await expect(page.getByRole("heading", { name: parentTitle })).toHaveCount(0)
+
+  const titlebarRight = page.locator("#opencode-titlebar-right")
+  await expect(titlebarRight.getByRole("button", { name: "Toggle review" })).toHaveCount(1)
+})
+
+test("shows the not found fallback when the viewed session is deleted", async ({ page }) => {
+  const events: EventPayload[] = []
+  await setup(page, () => events.splice(0, 1))
+  await openChildFromParent(page)
+  await expectSessionTitle(page, taskDescription)
+
+  events.push({
+    directory,
+    payload: { type: "session.deleted", properties: { info: childSession() } },
+  })
+
+  await expect(page.getByText("This session cannot be found")).toBeVisible()
+  await expect(page.getByRole("button", { name: "Close Tab", exact: true })).toBeVisible()
+  await expect(page.getByRole("heading", { name: taskDescription })).toHaveCount(0)
+})
+
+async function setup(page: Page, events?: () => EventPayload[]) {
+  await mockOpenCodeServer(page, {
+    directory,
+    project: {
+      id: projectID,
+      worktree: directory,
+      vcs: "git",
+      name: "subagent-navigation",
+      time: { created: 1700000000000, updated: 1700000000000 },
+      sandboxes: [],
+    },
+    provider: {
+      all: [
+        {
+          id: "opencode",
+          name: "OpenCode",
+          models: {
+            "claude-opus-4-6": { id: "claude-opus-4-6", name: "Claude Opus 4.6", limit: { context: 200_000 } },
+          },
+        },
+      ],
+      connected: ["opencode"],
+      default: { providerID: "opencode", modelID: "claude-opus-4-6" },
+    },
+    sessions: [session(parentID, parentTitle, 1700000000000), childSession()],
+    pageMessages: (sessionID) => ({ items: sessionID === parentID ? parentMessages() : [] }),
+    events,
+    eventRetry: events ? 16 : undefined,
+  })
+  // The child session resolves by ID but is absent from the session list,
+  // matching a subagent session that has not been loaded into the list cache yet.
+  await page.route(
+    (url) => url.pathname === "/api/session" && url.port === (process.env.PLAYWRIGHT_SERVER_PORT ?? "4096"),
+    (route) =>
+      route.fulfill({
+        status: 200,
+        contentType: "application/json",
+        headers: { "access-control-allow-origin": "*" },
+        body: JSON.stringify({
+          data: [currentSession(session(parentID, parentTitle, 1700000000000))],
+          cursor: {},
+        }),
+      }),
+  )
+  await configurePage(page)
+}
+
+async function openChildFromParent(page: Page) {
+  await page.goto(sessionHref(parentID))
+  await expectSessionTitle(page, parentTitle)
+
+  const card = page.locator(`a[href="${sessionHref(childID)}"]`)
+  await expect(card).toBeVisible()
+  await card.click()
+
+  await expect(page).toHaveURL(new RegExp(`/server/.+/session/${childID}$`), { timeout: 15_000 })
+}
+
+function session(id: string, title: string, created: number, extra?: Record<string, unknown>) {
+  return {
+    id,
+    slug: id,
+    projectID,
+    directory,
+    title,
+    version: "dev",
+    time: { created, updated: created },
+    ...extra,
+  }
+}
+
+function childSession() {
+  return session(childID, childTitle, 1700000001000, { parentID })
+}
+
+function parentMessages() {
+  const userID = "msg_user_0001"
+  const assistantID = "msg_assistant_0001"
+  return [
+    {
+      info: {
+        id: userID,
+        sessionID: parentID,
+        role: "user",
+        time: { created: 1700000000000 },
+        agent: "build",
+        model: { providerID: "opencode", modelID: "claude-opus-4-6" },
+      },
+      parts: [
+        {
+          id: "prt_user_text_0001",
+          sessionID: parentID,
+          messageID: userID,
+          type: "text",
+          text: "Delegate work to a subagent",
+        },
+      ],
+    },
+    {
+      info: {
+        id: assistantID,
+        sessionID: parentID,
+        role: "assistant",
+        time: { created: 1700000001000, completed: 1700000002000 },
+        parentID: userID,
+        modelID: "claude-opus-4-6",
+        providerID: "opencode",
+        mode: "build",
+        agent: "build",
+        path: { cwd: directory, root: directory },
+        cost: 0.01,
+        tokens: { input: 100, output: 200, reasoning: 0, cache: { read: 0, write: 0 } },
+        finish: "stop",
+      },
+      parts: [
+        {
+          id: "prt_tool_task_0001",
+          sessionID: parentID,
+          messageID: assistantID,
+          type: "tool",
+          callID: "call_task_0001",
+          tool: "task",
+          state: {
+            status: "completed",
+            input: { description: taskDescription, subagent_type: "explore" },
+            output: "Subagent finished",
+            title: taskDescription,
+            metadata: { sessionId: childID },
+            time: { start: 1700000001000, end: 1700000002000 },
+          },
+        },
+      ],
+    },
+  ]
+}
+
+async function configurePage(page: Page) {
+  const server = `http://${process.env.PLAYWRIGHT_SERVER_HOST ?? "127.0.0.1"}:${process.env.PLAYWRIGHT_SERVER_PORT ?? "4096"}`
+  await page.addInitScript(
+    ({ directory, server, sessionId }) => {
+      localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: true } }))
+      localStorage.setItem(
+        "opencode.global.dat:server",
+        JSON.stringify({
+          projects: { local: [{ worktree: directory, expanded: true }] },
+          lastProject: { local: directory },
+        }),
+      )
+      localStorage.setItem("opencode.window.browser.dat:tabs", JSON.stringify([{ type: "session", server, sessionId }]))
+    },
+    { directory, server, sessionId: parentID },
+  )
+}
+
+function sessionHref(sessionID: string) {
+  const server = `http://${process.env.PLAYWRIGHT_SERVER_HOST ?? "127.0.0.1"}:${process.env.PLAYWRIGHT_SERVER_PORT ?? "4096"}`
+  return `/server/${base64Encode(server)}/session/${sessionID}`
+}

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

@@ -0,0 +1,159 @@
+import { expect, test, type Page, type Route } from "@playwright/test"
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { currentSession } from "../utils/mock-server"
+
+const server = "http://127.0.0.1:4096"
+const sessionA = session("ses_tab_a", "Tab A session")
+const sessionB = session("ses_tab_b", "Tab B session")
+const sessionC = session("ses_tab_c", "Tab C session")
+const unresolvedSessionID = "ses_tab_unresolved"
+
+test("pressing mouse down on a tab navigates before mouse up", async ({ page }) => {
+  await mockServer(page)
+  await page.addInitScript(
+    ({ server, sessionA, sessionB }) => {
+      localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: true } }))
+      localStorage.setItem(
+        "opencode.window.browser.dat:tabs",
+        JSON.stringify([
+          { type: "session", server, sessionId: sessionA },
+          { type: "session", server, sessionId: sessionB },
+        ]),
+      )
+    },
+    { server, sessionA: sessionA.id, sessionB: sessionB.id },
+  )
+
+  const hrefA = `/server/${base64Encode(server)}/session/${sessionA.id}`
+  const hrefB = `/server/${base64Encode(server)}/session/${sessionB.id}`
+  await page.goto(hrefA)
+  await expect(page.getByText(sessionA.title).first()).toBeVisible()
+
+  const linkB = page.locator(`a[data-titlebar-tab-link][href="${hrefB}"]`)
+  await expect(linkB).toBeVisible()
+  const box = await linkB.boundingBox()
+  if (!box) throw new Error("tab link has no bounding box")
+  await page.mouse.move(box.x + box.width / 2, box.y + box.height / 2)
+  await page.mouse.down()
+
+  // Navigation must happen on mousedown, before the button is released.
+  await expect(page).toHaveURL(new RegExp(`${hrefB.replace(/[.*+?^${}()|[\]\\]/g, "\\$&")}$`))
+  await page.mouse.up()
+  await expect(page).toHaveURL(new RegExp(`${hrefB.replace(/[.*+?^${}()|[\]\\]/g, "\\$&")}$`))
+})
+
+test("keyboard navigation follows the visible tab order", async ({ page }) => {
+  await mockServer(page)
+  await page.addInitScript(
+    ({ server, sessionA, unresolved, sessionC }) => {
+      localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: true } }))
+      localStorage.setItem(
+        "opencode.window.browser.dat:tabs",
+        JSON.stringify([
+          { type: "session", server, sessionId: sessionA },
+          { type: "session", server, sessionId: unresolved },
+          { type: "session", server, sessionId: sessionC },
+        ]),
+      )
+    },
+    { server, sessionA: sessionA.id, unresolved: unresolvedSessionID, sessionC: sessionC.id },
+  )
+
+  const hrefA = `/server/${base64Encode(server)}/session/${sessionA.id}`
+  const hrefC = `/server/${base64Encode(server)}/session/${sessionC.id}`
+  await page.goto(hrefA)
+  await expect(page.locator("[data-titlebar-tab-slot]:visible")).toHaveCount(2)
+  await expect(page.locator(`[data-titlebar-tab-slot]:has(a[href="${hrefC}"])`)).toBeVisible()
+
+  await page.keyboard.press("Control+Alt+ArrowRight")
+
+  await expect(page).toHaveURL(new RegExp(`${hrefC.replace(/[.*+?^${}()|[\]\\]/g, "\\$&")}$`))
+})
+
+function session(id: string, title: string) {
+  return {
+    id,
+    slug: id,
+    projectID: "project-tabs",
+    directory: "C:/tab-project",
+    title,
+    version: "dev",
+    time: { created: 1, updated: 1 },
+  }
+}
+
+async function mockServer(page: Page) {
+  const sessions = [sessionA, sessionB, sessionC]
+  await page.route("**/*", async (route) => {
+    const url = new URL(route.request().url())
+    if (url.origin !== server) return route.fallback()
+    if ([`/api/session/${unresolvedSessionID}`, `/session/${unresolvedSessionID}`].includes(url.pathname))
+      return new Promise(() => {})
+    if (url.pathname === "/global/event" || url.pathname === "/event" || url.pathname === "/api/event")
+      return sse(route)
+    if (url.pathname === "/global/health") return json(route, { healthy: true })
+    if (url.pathname === "/api/session") return json(route, { data: sessions.map(currentSession), cursor: {} })
+    if (url.pathname === "/api/session/active") return json(route, { data: {} })
+    const currentSessionInfo = sessions.find((item) => url.pathname === `/api/session/${item.id}`)
+    if (currentSessionInfo) return json(route, { data: currentSession(currentSessionInfo) })
+    if (sessions.some((item) => url.pathname === `/api/session/${item.id}/message`))
+      return json(route, { data: [], cursor: {} })
+    const byId = sessions.find((item) => url.pathname === `/session/${item.id}`)
+    if (byId) return json(route, byId)
+    if (/^\/session\/[^/]+$/.test(url.pathname)) return json(route, { name: "NotFoundError" }, 404)
+    if (/^\/session\/[^/]+\/message$/.test(url.pathname)) return json(route, [])
+    if (/^\/session\/[^/]+\/(children|todo|diff)$/.test(url.pathname)) return json(route, [])
+    if (["/skill", "/command", "/lsp", "/formatter", "/permission", "/question", "/vcs/diff"].includes(url.pathname))
+      return json(route, [])
+    if (["/global/config", "/config", "/provider/auth", "/mcp"].includes(url.pathname)) return json(route, {})
+    if (url.pathname === "/provider")
+      return json(route, { all: [], connected: [], default: { providerID: "", modelID: "" } })
+    if (url.pathname === "/agent") return json(route, [{ name: "build", mode: "primary" }])
+    if (url.pathname === "/project" || url.pathname === "/project/current") {
+      const project = {
+        id: sessionA.projectID,
+        worktree: sessionA.directory,
+        vcs: "git",
+        time: { created: 1, updated: 1 },
+        sandboxes: [],
+      }
+      return json(route, url.pathname === "/project" ? [project] : project)
+    }
+    if (url.pathname === "/path")
+      return json(route, {
+        state: sessionA.directory,
+        config: sessionA.directory,
+        worktree: sessionA.directory,
+        directory: sessionA.directory,
+        home: sessionA.directory,
+      })
+    if (url.pathname === "/api/path")
+      return json(route, {
+        state: sessionA.directory,
+        config: sessionA.directory,
+        worktree: sessionA.directory,
+        directory: sessionA.directory,
+        home: sessionA.directory,
+      })
+    if (url.pathname === "/vcs") return json(route, { branch: "main", default_branch: "main" })
+    if (url.pathname === "/api/vcs")
+      return json(route, {
+        location: { directory: sessionA.directory },
+        data: { branch: "main", defaultBranch: "main" },
+      })
+    return json(route, {})
+  })
+}
+
+function json(route: Route, body: unknown, status = 200) {
+  return route.fulfill({
+    status,
+    contentType: "application/json",
+    headers: { "access-control-allow-origin": "*" },
+    body: JSON.stringify(body),
+  })
+}
+
+function sse(route: Route) {
+  return route.fulfill({ status: 200, contentType: "text/event-stream", body: ": ok\n\n" })
+}

packages/app/e2e/regression/terminal-composer-focus.spec.ts

@@ -0,0 +1,227 @@
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { expect, test, type Page } from "@playwright/test"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectSessionTitle } from "../utils/waits"
+
+const directory = "C:/OpenCode/TerminalComposerFocus"
+const projectID = "proj_terminal_composer_focus"
+const sessionID = "ses_terminal_composer_focus"
+const ptyID = "pty_terminal_composer_focus"
+const newPtyID = "pty_terminal_composer_focus_new"
+
+test.use({ viewport: { width: 1440, height: 900 } })
+
+test.beforeEach(async ({ page }) => {
+  await mockOpenCodeServer(page, {
+    protocol: "v2",
+    directory,
+    project: {
+      id: projectID,
+      worktree: directory,
+      vcs: "git",
+      name: "terminal-composer-focus",
+      time: { created: 1700000000000, updated: 1700000000000 },
+      sandboxes: [],
+    },
+    provider: {
+      all: [
+        {
+          id: "opencode",
+          name: "OpenCode",
+          models: { test: { id: "test", name: "Test", limit: { context: 200_000 } } },
+        },
+      ],
+      connected: ["opencode"],
+      default: { providerID: "opencode", modelID: "test" },
+    },
+    sessions: [
+      {
+        id: sessionID,
+        slug: "terminal-composer-focus",
+        projectID,
+        directory,
+        title: "Terminal composer focus",
+        version: "dev",
+        time: { created: 1700000000000, updated: 1700000000000 },
+      },
+    ],
+    pageMessages: () => ({ items: [] }),
+  })
+  await page.route("**/api/pty*", (route) => {
+    expect(new URL(route.request().url()).searchParams.get("location[directory]")).toBe(directory)
+    return route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      body: JSON.stringify({ location: ptyLocation(), data: ptyInfo(ptyID, "Terminal 1") }),
+    })
+  })
+  await page.route(`**/api/pty/${ptyID}*`, (route) =>
+    route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      body: JSON.stringify({ location: ptyLocation(), data: ptyInfo(ptyID, "Terminal 1") }),
+    }),
+  )
+  await page.route(`**/api/pty/${ptyID}/connect-token*`, (route) =>
+    route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      headers: { "access-control-allow-origin": "*" },
+      body: JSON.stringify({ location: ptyLocation(), data: { ticket: "e2e-ticket", expires_in: 60 } }),
+    }),
+  )
+  await page.routeWebSocket(new RegExp(`/api/pty/${ptyID}/connect`), () => undefined)
+  await page.addInitScript(() => {
+    localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: true } }))
+  })
+})
+
+test("routes typing to the composer unless the open terminal is focused", async ({ page }) => {
+  await page.goto(`/${base64Encode(directory)}/session/${sessionID}`)
+  await expectSessionTitle(page, "Terminal composer focus")
+
+  const composer = page.locator('[data-component="prompt-input"]')
+  const terminal = page.locator('[data-component="terminal"]')
+  await page.keyboard.press("Control+Backquote")
+  await expect(terminal).toBeVisible()
+  await expect.poll(() => terminal.evaluate((element) => element.contains(document.activeElement))).toBe(true)
+
+  await page.keyboard.type("x")
+  await expect(composer).toHaveText("")
+
+  await page.waitForTimeout(300)
+  await page.evaluate(() => (document.activeElement as HTMLElement | null)?.blur())
+  await page.keyboard.type("a")
+
+  await expect(composer).toBeFocused()
+  await expect(composer).toHaveText("a")
+})
+
+test("keeps composer focus when a cached terminal finishes mounting", async ({ page }) => {
+  const ghostty = Promise.withResolvers<void>()
+  const release = Promise.withResolvers<void>()
+  const created = { count: 0 }
+  await page.route("**/api/pty*", (route) => {
+    created.count += 1
+    return route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      body: JSON.stringify({ location: ptyLocation(), data: ptyInfo(ptyID, "Terminal 1") }),
+    })
+  })
+  await page.route(/ghostty-web/, async (route) => {
+    ghostty.resolve()
+    await release.promise
+    await route.continue()
+  })
+  await seedCachedTerminal(page)
+
+  await page.goto(`/${base64Encode(directory)}/session/${sessionID}`, { waitUntil: "commit" })
+  await expectSessionTitle(page, "Terminal composer focus")
+
+  const composer = page.locator('[data-component="prompt-input"]')
+  const terminal = page.locator('[data-component="terminal"]')
+  await expect(terminal).toBeVisible()
+  expect(created.count).toBe(0)
+  await ghostty.promise
+  await composer.click()
+  await expect(composer).toBeFocused()
+
+  release.resolve()
+  await expect(terminal.locator("textarea")).toHaveCount(1)
+  await page.waitForTimeout(300)
+  await expect(composer).toBeFocused()
+})
+
+test("keeps newer composer focus while an explicit terminal open finishes", async ({ page }) => {
+  const ghostty = Promise.withResolvers<void>()
+  const release = Promise.withResolvers<void>()
+  await page.route(/ghostty-web/, async (route) => {
+    ghostty.resolve()
+    await release.promise
+    await route.continue()
+  })
+
+  await page.goto(`/${base64Encode(directory)}/session/${sessionID}`)
+  await expectSessionTitle(page, "Terminal composer focus")
+
+  const composer = page.locator('[data-component="prompt-input"]')
+  const terminal = page.locator('[data-component="terminal"]')
+  await page.keyboard.press("Control+Backquote")
+  await expect(terminal).toBeVisible()
+  await ghostty.promise
+  await composer.click()
+  await expect(composer).toBeFocused()
+
+  release.resolve()
+  await expect(terminal.locator("textarea")).toHaveCount(1)
+  await page.waitForTimeout(50)
+  await expect(composer).toBeFocused()
+})
+
+test("focuses a terminal created from the new-terminal button", async ({ page }) => {
+  const created = { count: 0 }
+  await page.route("**/api/pty*", (route) => {
+    created.count += 1
+    const next = created.count === 1 ? ptyInfo(ptyID, "Terminal 1") : ptyInfo(newPtyID, "Terminal 2")
+    return route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      body: JSON.stringify({ location: ptyLocation(), data: next }),
+    })
+  })
+  await page.route(`**/api/pty/${newPtyID}*`, (route) =>
+    route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      body: JSON.stringify({ location: ptyLocation(), data: ptyInfo(newPtyID, "Terminal 2") }),
+    }),
+  )
+  await page.route(`**/api/pty/${newPtyID}/connect-token*`, (route) =>
+    route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      headers: { "access-control-allow-origin": "*" },
+      body: JSON.stringify({ location: ptyLocation(), data: { ticket: "e2e-ticket", expires_in: 60 } }),
+    }),
+  )
+  await page.routeWebSocket(new RegExp(`/api/pty/${newPtyID}/connect`), () => undefined)
+
+  await page.goto(`/${base64Encode(directory)}/session/${sessionID}`)
+  await expectSessionTitle(page, "Terminal composer focus")
+
+  const composer = page.locator('[data-component="prompt-input"]')
+  const terminal = page.locator('[data-component="terminal"]')
+  await page.keyboard.press("Control+Backquote")
+  await expect(terminal.locator("textarea")).toHaveCount(1)
+  await composer.click()
+  await expect(composer).toBeFocused()
+
+  await page.getByRole("button", { name: "New terminal" }).click()
+  await expect(page.getByRole("tab", { name: "Terminal 2" })).toHaveAttribute("aria-selected", "true")
+  await expect.poll(() => terminal.evaluate((element) => element.contains(document.activeElement))).toBe(true)
+})
+
+function seedCachedTerminal(page: Page) {
+  return page.addInitScript(
+    ({ terminalKey, ptyID }) => {
+      localStorage.setItem("opencode.global.dat:layout", JSON.stringify({ terminal: { height: 320, opened: true } }))
+      localStorage.setItem(
+        terminalKey,
+        JSON.stringify({
+          active: ptyID,
+          all: [{ id: ptyID, title: "Terminal 1", titleNumber: 1 }],
+        }),
+      )
+    },
+    { terminalKey: `${base64Encode(directory)}/terminal.v1`, ptyID },
+  )
+}
+
+function ptyLocation() {
+  return { directory, project: { id: projectID, directory } }
+}
+
+function ptyInfo(id: string, title: string) {
+  return { id, title, command: "cmd.exe", args: [], cwd: directory, status: "running", pid: 1 }
+}

packages/app/e2e/regression/terminal-hidden.spec.ts

@@ -0,0 +1,117 @@
+import { expect, test } from "@playwright/test"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectSessionTitle } from "../utils/waits"
+
+const directory = "C:/OpenCode/HiddenTerminalRegression"
+const projectID = "proj_hidden_terminal_regression"
+const sessionID = "ses_hidden_terminal_regression"
+const title = "Hidden terminal regression"
+
+test("unmounts the terminal panel while it is hidden", async ({ page }) => {
+  await page.setViewportSize({ width: 1400, height: 900 })
+  await mockOpenCodeServer(page, {
+    protocol: "v2",
+    directory,
+    project: {
+      id: projectID,
+      worktree: directory,
+      vcs: "git",
+      name: "hidden-terminal-regression",
+      time: { created: 1700000000000, updated: 1700000000000 },
+      sandboxes: [],
+    },
+    provider: {
+      all: [
+        {
+          id: "opencode",
+          name: "OpenCode",
+          models: { test: { id: "test", name: "Test", limit: { context: 200_000 } } },
+        },
+      ],
+      connected: ["opencode"],
+      default: { providerID: "opencode", modelID: "test" },
+    },
+    sessions: [
+      {
+        id: sessionID,
+        slug: "hidden-terminal-regression",
+        projectID,
+        directory,
+        title,
+        version: "dev",
+        time: { created: 1700000000000, updated: 1700000000000 },
+      },
+    ],
+    pageMessages: () => ({ items: [] }),
+  })
+  await page.route("**/api/pty*", (route) =>
+    route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      body: JSON.stringify({
+        location: { directory, project: { id: projectID, directory } },
+        data: {
+          id: "pty_hidden_terminal",
+          title: "Terminal 1",
+          command: "cmd.exe",
+          args: [],
+          cwd: directory,
+          status: "running",
+          pid: 1,
+        },
+      }),
+    }),
+  )
+  await page.route("**/api/pty/pty_hidden_terminal*", (route) =>
+    route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      body: JSON.stringify({
+        location: { directory, project: { id: projectID, directory } },
+        data: {
+          id: "pty_hidden_terminal",
+          title: "Terminal 1",
+          command: "cmd.exe",
+          args: [],
+          cwd: directory,
+          status: "running",
+          pid: 1,
+        },
+      }),
+    }),
+  )
+  await page.route("**/api/pty/pty_hidden_terminal/connect-token*", (route) =>
+    route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      body: JSON.stringify({
+        location: { directory, project: { id: projectID, directory } },
+        data: { ticket: "e2e-ticket", expires_in: 60 },
+      }),
+    }),
+  )
+  await page.routeWebSocket("**/api/pty/pty_hidden_terminal/connect", () => undefined)
+
+  await page.goto(`/${base64Encode(directory)}/session/${sessionID}`)
+  await expectSessionTitle(page, title)
+
+  await page.keyboard.press("Control+Backquote")
+  const panel = page.locator("#terminal-panel")
+  await expect(panel).toHaveAttribute("aria-hidden", "false")
+  await expect(page.locator('[data-component="terminal"]')).toBeVisible()
+
+  await page.keyboard.press("Control+Backquote")
+  await expect(panel).toHaveCount(0)
+  await expect(page.locator('[data-component="terminal"]')).toHaveCount(0)
+
+  await page.setViewportSize({ width: 1200, height: 700 })
+  await expect(page.locator('[data-component="terminal"]')).toHaveCount(0)
+
+  await page.keyboard.press("Control+Backquote")
+  await expect(panel).toBeVisible()
+  await expect(page.locator('[data-component="terminal"]')).toBeVisible()
+})
+
+function base64Encode(value: string) {
+  return Buffer.from(value, "utf8").toString("base64").replace(/\+/g, "-").replace(/\//g, "_").replace(/=/g, "")
+}

packages/app/e2e/regression/terminal-tab-switch.spec.ts

@@ -0,0 +1,165 @@
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { expect, test, type Page } from "@playwright/test"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectSessionTitle } from "../utils/waits"
+
+const directory = "C:/OpenCode/TerminalTabSwitch"
+const projectID = "proj_terminal_tab_switch"
+const sessionA = "ses_terminal_tab_a"
+const sessionB = "ses_terminal_tab_b"
+const titleA = "Alpha session"
+const titleB = "Beta session"
+const ptyID = "pty_tab_switch"
+const server = `http://${process.env.PLAYWRIGHT_SERVER_HOST ?? "127.0.0.1"}:${process.env.PLAYWRIGHT_SERVER_PORT ?? "4096"}`
+// Marks the terminal DOM node so a remount (fresh node) is detectable.
+const PROBE = "original"
+
+test.use({ viewport: { width: 1440, height: 900 } })
+
+// Terminals are workspace-scoped: switching between session tabs in the same
+// workspace must keep the terminal mounted and its PTY connection open instead
+// of tearing it down and reconnecting.
+test("keeps the terminal session alive when switching session tabs in a workspace", async ({ page }) => {
+  const connections = await setup(page)
+
+  await page.goto(sessionHref(sessionA))
+  await expectSessionTitle(page, titleA)
+
+  await page.keyboard.press("Control+Backquote")
+  const terminal = page.locator('[data-component="terminal"]')
+  await expect(terminal).toBeVisible()
+  await expect.poll(() => connections.length).toBe(1)
+  const connection = new URL(connections[0]!)
+  expect(connection.pathname).toBe(`/api/pty/${ptyID}/connect`)
+  expect(connection.searchParams.get("location[directory]")).toBe(directory)
+  expect(connection.searchParams.get("ticket")).toBeNull()
+  await writeProbe(page)
+
+  await switchTab(page, titleB)
+  await expectSessionTitle(page, titleB)
+  await expect(terminal).toBeVisible()
+  expect(await readProbe(page)).toBe(PROBE)
+  expect(connections.length).toBe(1)
+
+  await switchTab(page, titleA)
+  await expectSessionTitle(page, titleA)
+  await expect(terminal).toBeVisible()
+  expect(await readProbe(page)).toBe(PROBE)
+  expect(connections.length).toBe(1)
+})
+
+type Probed = HTMLElement & { __e2eProbe?: string }
+
+async function switchTab(page: Page, title: string) {
+  await page.locator("[data-titlebar-tab-slot]", { hasText: title }).click()
+}
+
+async function writeProbe(page: Page) {
+  await page.locator('[data-component="terminal"]').evaluate((el, probe) => {
+    ;(el as Probed).__e2eProbe = probe
+  }, PROBE)
+}
+
+async function readProbe(page: Page) {
+  return page.locator('[data-component="terminal"]').evaluate((el) => (el as Probed).__e2eProbe)
+}
+
+async function setup(page: Page) {
+  await mockOpenCodeServer(page, {
+    protocol: "v2",
+    directory,
+    project: {
+      id: projectID,
+      worktree: directory,
+      vcs: "git",
+      name: "terminal-tab-switch",
+      time: { created: 1700000000000, updated: 1700000000000 },
+      sandboxes: [],
+    },
+    provider: {
+      all: [
+        {
+          id: "opencode",
+          name: "OpenCode",
+          models: { test: { id: "test", name: "Test", limit: { context: 200_000 } } },
+        },
+      ],
+      connected: ["opencode"],
+      default: { providerID: "opencode", modelID: "test" },
+    },
+    sessions: [session(sessionA, titleA, 1700000000000), session(sessionB, titleB, 1700000001000)],
+    pageMessages: () => ({ items: [] }),
+  })
+  await page.route("**/api/pty*", (route) =>
+    route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      body: JSON.stringify({ location: ptyLocation(), data: ptyInfo() }),
+    }),
+  )
+  await page.route(`**/api/pty/${ptyID}*`, (route) =>
+    route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      body: JSON.stringify({ location: ptyLocation(), data: ptyInfo() }),
+    }),
+  )
+  await page.route(`**/api/pty/${ptyID}/connect-token*`, (route) => {
+    expect(route.request().headers()["x-opencode-ticket"]).toBe("1")
+    const url = new URL(route.request().url())
+    expect(url.searchParams.get("location[directory]")).toBe(directory)
+    return route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      headers: { "access-control-allow-origin": "*" },
+      body: JSON.stringify({ location: ptyLocation(), data: { ticket: "e2e-ticket", expires_in: 60 } }),
+    })
+  })
+  const connections: string[] = []
+  await page.routeWebSocket(new RegExp(`/api/pty/${ptyID}/connect`), (ws) => {
+    connections.push(ws.url())
+  })
+
+  await page.addInitScript(
+    ({ directory, server, sessions }) => {
+      localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: true } }))
+      localStorage.setItem(
+        "opencode.global.dat:server",
+        JSON.stringify({
+          projects: { local: [{ worktree: directory, expanded: true }] },
+          lastProject: { local: directory },
+        }),
+      )
+      localStorage.setItem(
+        "opencode.window.browser.dat:tabs",
+        JSON.stringify(sessions.map((sessionId: string) => ({ type: "session", server, sessionId }))),
+      )
+    },
+    { directory, server, sessions: [sessionA, sessionB] },
+  )
+  return connections
+}
+
+function session(id: string, title: string, created: number) {
+  return {
+    id,
+    slug: id,
+    projectID,
+    directory,
+    title,
+    version: "dev",
+    time: { created, updated: created },
+  }
+}
+
+function sessionHref(sessionID: string) {
+  return `/server/${base64Encode(server)}/session/${sessionID}`
+}
+
+function ptyLocation() {
+  return { directory, project: { id: projectID, directory } }
+}
+
+function ptyInfo() {
+  return { id: ptyID, title: "Terminal 1", command: "cmd.exe", args: [], cwd: directory, status: "running", pid: 1 }
+}

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

@@ -0,0 +1,315 @@
+const words = [
+  "alpha",
+  "bravo",
+  "charlie",
+  "delta",
+  "echo",
+  "foxtrot",
+  "golf",
+  "hotel",
+  "india",
+  "juliet",
+  "kilo",
+  "lima",
+  "metro",
+  "nova",
+  "orbit",
+  "pixel",
+  "quartz",
+  "river",
+  "signal",
+  "vector",
+]
+
+const serverKey = "http://127.0.0.1:4096"
+const sourceID = "ses_smoke_source"
+const targetID = "ses_smoke_target"
+const directory = "C:/OpenCode/SmokeProject"
+const projectID = "proj_smoke_timeline"
+const model = { providerID: "opencode", modelID: "claude-opus-4-6", variant: "max" }
+
+type MessageInfo = Record<string, unknown> & { id: string; role: "user" | "assistant" }
+type MessagePart = Record<string, unknown> & { id: string; type: string; text?: string; tool?: string }
+type Message = { info: MessageInfo; parts: MessagePart[] }
+
+function lorem(seed: number, length: number) {
+  let out = ""
+  let i = seed
+  while (out.length < length) {
+    const word = words[i % words.length]
+    out += (out ? " " : "") + word
+    if (i % 17 === 0) out += ".\n\n"
+    i += 7
+  }
+  return out.slice(0, length)
+}
+
+function id(prefix: string, value: number) {
+  return `${prefix}_smoke_${String(value).padStart(4, "0")}`
+}
+
+function userMessage(sessionID: string, index: number, textLength: number, diffs: unknown[] = []): Message {
+  const messageID = id("msg_user", index)
+  return {
+    info: {
+      id: messageID,
+      sessionID,
+      role: "user",
+      time: { created: 1700000000000 + index * 10_000 },
+      summary: { diffs },
+      agent: "build",
+      model,
+    },
+    parts: [
+      {
+        id: id("prt_user_text", index),
+        sessionID,
+        messageID,
+        type: "text",
+        text: lorem(index, textLength),
+      },
+    ],
+  }
+}
+
+function assistantMessage(sessionID: string, index: number, parentID: string, parts: MessagePart[]): Message {
+  const messageID = id("msg_assistant", index)
+  return {
+    info: {
+      id: messageID,
+      sessionID,
+      role: "assistant",
+      time: { created: 1700000000000 + index * 10_000 + 1_000, completed: 1700000000000 + index * 10_000 + 8_000 },
+      parentID,
+      modelID: model.modelID,
+      providerID: model.providerID,
+      mode: "build",
+      agent: "build",
+      path: { cwd: directory, root: directory },
+      cost: 0.01,
+      tokens: { input: 100, output: 200, reasoning: 0, cache: { read: 0, write: 0 } },
+      variant: "max",
+      finish: "stop",
+    },
+    parts: parts.map((part) => ({
+      ...part,
+      sessionID,
+      messageID,
+    })),
+  }
+}
+
+function textPart(index: number, partIndex: number, length: number): MessagePart {
+  return { id: id(`prt_text_${partIndex}`, index), type: "text", text: lorem(index * 13 + partIndex, length) }
+}
+
+function reasoningPart(index: number, partIndex: number, length: number): MessagePart {
+  return {
+    id: id(`prt_reasoning_${partIndex}`, index),
+    type: "reasoning",
+    text: lorem(index * 19 + partIndex, length),
+    time: { start: 1700000000000 + index * 10_000, end: 1700000000000 + index * 10_000 + 500 },
+  }
+}
+
+function toolPart(
+  index: number,
+  partIndex: number,
+  tool: string,
+  input: Record<string, unknown>,
+  outputLength = 160,
+): MessagePart {
+  const metadata =
+    tool === "apply_patch"
+      ? { files: [patchFile(index, "update"), patchFile(index + 1, index % 2 === 0 ? "add" : "delete")] }
+      : tool === "edit" || tool === "write"
+        ? {
+            filediff: fileDiff(String(input.filePath ?? `src/generated/file-${index}.ts`), index),
+            diff: patch(index, outputLength),
+            preview: patch(index + 1, 420),
+          }
+        : tool === "question"
+          ? { answers: [["Proceed"], ["Keep sample output"]] }
+          : {}
+  return {
+    id: id(`prt_tool_${tool}_${partIndex}`, index),
+    type: "tool",
+    callID: id("call", index * 10 + partIndex),
+    tool,
+    state: {
+      status: "completed",
+      input,
+      output: lorem(index * 23 + partIndex, outputLength),
+      title: tool === "bash" ? input.command : input.filePath || input.path || input.pattern || "completed",
+      metadata,
+      time: { start: 1700000000000 + index * 10_000, end: 1700000000000 + index * 10_000 + 400 },
+    },
+  }
+}
+
+function patchFile(seed: number, type: "add" | "update" | "delete") {
+  return {
+    filePath: `src/generated/patch-${seed}.ts`,
+    relativePath: `src/generated/patch-${seed}.ts`,
+    type,
+    additions: (seed % 7) + 1,
+    deletions: type === "add" ? 0 : seed % 4,
+    patch: patch(seed, 520),
+    before: type === "add" ? undefined : code(seed, 18),
+    after: type === "delete" ? undefined : code(seed + 1, 24),
+  }
+}
+
+function fileDiff(file: string, seed: number) {
+  return {
+    file,
+    additions: (seed % 9) + 1,
+    deletions: seed % 4,
+    before: code(seed, 32),
+    after: code(seed + 1, 38),
+  }
+}
+
+function patch(seed: number, length: number) {
+  return `diff --git a/src/generated/file-${seed}.ts b/src/generated/file-${seed}.ts\n+${lorem(seed, length).replace(/\n/g, "\n+")}`
+}
+
+function code(seed: number, lines: number) {
+  return Array.from({ length: lines }, (_, index) => `export const value${index} = "${lorem(seed + index, 32)}"`).join(
+    "\n",
+  )
+}
+
+function turn(index: number): Message[] {
+  const diff = index % 9 === 0 ? [fileDiff(`src/generated/summary-${index}.ts`, index)] : []
+  const user = userMessage(targetID, index, 100 + (index % 4) * 80, diff)
+  const parts = [
+    ...(index % 5 === 0 ? [reasoningPart(index, 0, 420)] : []),
+    ...(index % 3 === 0
+      ? [
+          toolPart(index, 0, "read", { filePath: `src/generated/file-${index}.ts`, offset: 0, limit: 80 }, 220),
+          toolPart(index, 5, "glob", { path: directory, pattern: `**/*sample-${index}*.ts` }, 140),
+          toolPart(index, 1, "grep", { path: directory, pattern: `sample-${index}`, include: "*.ts" }, 180),
+          toolPart(index, 6, "list", { path: `src/generated/${index}` }, 120),
+        ]
+      : []),
+    textPart(index, 2, 160 + (index % 6) * 90),
+    ...(index % 4 === 0 ? [toolPart(index, 3, "edit", { filePath: `src/generated/file-${index}.ts` }, 700)] : []),
+    ...(index % 6 === 0
+      ? [toolPart(index, 7, "write", { filePath: `src/generated/write-${index}.ts`, content: code(index, 28) }, 560)]
+      : []),
+    ...(index % 8 === 0
+      ? [toolPart(index, 8, "apply_patch", { files: [`src/generated/patch-${index}.ts`] }, 620)]
+      : []),
+    ...(index % 7 === 0 ? [toolPart(index, 4, "bash", { command: "bun typecheck" }, 620)] : []),
+    ...(index % 10 === 0 ? [toolPart(index, 9, "webfetch", { url: "https://example.com/docs/sample" }, 120)] : []),
+    ...(index % 11 === 0 ? [toolPart(index, 10, "websearch", { query: "sample movement notes" }, 240)] : []),
+    ...(index % 13 === 0
+      ? [
+          toolPart(
+            index,
+            11,
+            "question",
+            { questions: [{ question: "Use generated fixture?" }, { question: "Keep same row shape?" }] },
+            120,
+          ),
+        ]
+      : []),
+    ...(index % 17 === 0
+      ? [toolPart(index, 12, "task", { description: "Inspect generated fixture", subagent_type: "explore" }, 160)]
+      : []),
+  ]
+  return [user, assistantMessage(targetID, index, user.info.id, parts)]
+}
+
+const targetMessages = Array.from({ length: 72 }, (_, index) => turn(index)).flat()
+const sourceMessages = Array.from({ length: 12 }, (_, index) => [
+  userMessage(sourceID, index + 1000, 120),
+  assistantMessage(sourceID, index + 1000, id("msg_user", index + 1000), [textPart(index + 1000, 0, 240)]),
+]).flat()
+
+function renderable(part: MessagePart) {
+  if (part.type === "tool" && part.tool === "todowrite") return false
+  if (part.type === "text") return !!part.text.trim()
+  if (part.type === "reasoning") return !!part.text.trim()
+  return part.type !== "step-start" && part.type !== "step-finish" && part.type !== "patch"
+}
+
+function orderedParts(message: Message) {
+  return message.parts.slice().sort((a, b) => a.id.localeCompare(b.id))
+}
+
+export const fixture = {
+  directory,
+  serverKey,
+  project: {
+    id: projectID,
+    worktree: directory,
+    vcs: "git",
+    name: "smoke-project",
+    time: { created: 1700000000000, updated: 1700000000000 },
+    sandboxes: [],
+  },
+  provider: {
+    all: [
+      {
+        id: "opencode",
+        name: "OpenCode",
+        models: { "claude-opus-4-6": { id: "claude-opus-4-6", name: "Claude Opus 4.6", limit: { context: 200_000 } } },
+      },
+    ],
+    connected: ["opencode"],
+    default: { providerID: "opencode", modelID: "claude-opus-4-6" },
+  },
+  sessions: [
+    {
+      id: sourceID,
+      slug: "source",
+      projectID,
+      directory,
+      title: "Uncommitted changes inquiry",
+      version: "dev",
+      time: { created: 1700000000000, updated: 1700000000000 },
+    },
+    {
+      id: targetID,
+      slug: "target",
+      projectID,
+      directory,
+      title: "Example Game: sample jump movement & sample physics analysis",
+      version: "dev",
+      time: { created: 1700000001000, updated: 1700000001000 },
+    },
+  ],
+  sourceID,
+  targetID,
+  messages: { [sourceID]: sourceMessages, [targetID]: targetMessages },
+  expected: {
+    sourceTitle: "Uncommitted changes inquiry",
+    targetTitle: "Example Game: sample jump movement & sample physics analysis",
+    targetMessageIDs: targetMessages
+      .filter((message) => message.info.role === "user")
+      .map((message) => message.info.id),
+    targetPartIDs: targetMessages.flatMap((message) =>
+      orderedParts(message)
+        .filter(renderable)
+        .map((part) => part.id),
+    ),
+    expandedShellPartID: targetMessages.flatMap((message) => message.parts).find((part) => part.tool === "bash")!.id,
+  },
+}
+
+export function pageMessages(sessionID: string, limit: number, before?: string) {
+  const messages = fixture.messages[sessionID as keyof typeof fixture.messages] ?? []
+  const end = before
+    ? Math.max(
+        0,
+        messages.findIndex((message) => message.info.id === before),
+      )
+    : messages.length
+  const start = Math.max(0, end - limit)
+  return {
+    items: messages.slice(start, end),
+    cursor: start > 0 ? messages[start]!.info.id : undefined,
+  }
+}

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

@@ -0,0 +1,740 @@
+import { expect, test, type Page } from "@playwright/test"
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { fixture, pageMessages } from "./session-timeline.fixture"
+import { trackPageErrors, expectNoSmokeErrors } from "../utils/errors"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { APP_READY_TIMEOUT, expectAppVisible, expectSessionTitle } from "../utils/waits"
+
+const forbiddenText = ["Load details", "Show earlier steps"]
+
+type SmokeState = {
+  ids: string[]
+  visibleIds: string[]
+  messageIds: string[]
+  visibleMessageIds: string[]
+  topVisibleId?: string
+  signature: string
+  scrollTop: number
+  scrollHeight: number
+  clientHeight: number
+  errorToasts: string[]
+  forbiddenText: string[]
+}
+
+type SmokeWindow = Window & {
+  __timelineSmokeState?: () => SmokeState
+  __timelineSmokeErrorToasts?: string[]
+  __timelineSmokeForbiddenText?: string[]
+}
+
+test.describe("smoke: session timeline", () => {
+  test.setTimeout(240_000)
+
+  test("keeps the visible message fixed while prepending history", async ({ page }) => {
+    const requests: { before?: string; phase: "start" | "end"; at: number }[] = []
+    await mockOpenCodeServer(page, {
+      sessions: fixture.sessions,
+      provider: fixture.provider,
+      directory: fixture.directory,
+      project: fixture.project,
+      pageMessages,
+      messageDelay: 3_000,
+      onMessages: (input) => requests.push({ before: input.before, phase: input.phase, at: performance.now() }),
+    })
+    await configureSmokePage(page, fixture.directory)
+
+    await navigateToSession(page, fixture.directory, fixture.targetID, fixture.expected.targetTitle)
+    await waitForTimelineStable(page)
+    const scroller = timelineScroller(page)
+    await pointAtTimeline(page)
+    const deadline = Date.now() + 120_000
+    while (!requests.some((request) => request.before && request.phase === "start")) {
+      if (Date.now() >= deadline) throw new Error("Timed out scrolling to the history boundary")
+      await page.mouse.wheel(0, -240)
+      await page.waitForTimeout(20)
+    }
+    expect(requests.some((request) => request.before && request.phase === "end")).toBe(false)
+    for (let index = 0; index < 12; index++) {
+      await page.mouse.wheel(0, -120)
+      await page.waitForTimeout(20)
+    }
+    const keys = await scroller.evaluate((element) => {
+      const view = element.getBoundingClientRect()
+      return [...element.querySelectorAll<HTMLElement>("[data-timeline-part-id]")]
+        .filter((row) => {
+          const rect = row.getBoundingClientRect()
+          return rect.bottom > view.top && rect.top < view.bottom
+        })
+        .map((row) => row.dataset.timelinePartId)
+        .filter((id): id is string => !!id)
+        .slice(0, 3)
+    })
+    expect(keys.length).toBeGreaterThan(0)
+    const positions = () =>
+      scroller.evaluate((element, keys) => {
+        const top = element.getBoundingClientRect().top
+        return Object.fromEntries(
+          keys.map((key) => {
+            const row = element.querySelector<HTMLElement>(`[data-timeline-part-id="${key}"]`)
+            if (!row) throw new Error(`Missing stable timeline key: ${key}`)
+            return [key, Math.round((row.getBoundingClientRect().top - top) * devicePixelRatio) / devicePixelRatio]
+          }),
+        )
+      }, keys)
+    const before = await positions()
+    expect(requests.some((request) => request.before && request.phase === "end")).toBe(false)
+
+    await expect.poll(() => requests.some((request) => request.before && request.phase === "end")).toBe(true)
+    await waitForTimelineStable(page)
+    await expect.poll(positions).toEqual(before)
+  })
+
+  test("preserves the timeline gap above the composer", async ({ page }) => {
+    await mockOpenCodeServer(page, {
+      sessions: fixture.sessions,
+      provider: fixture.provider,
+      directory: fixture.directory,
+      project: fixture.project,
+      pageMessages,
+    })
+    await configureSmokePage(page, fixture.directory)
+
+    await navigateToSession(page, fixture.directory, fixture.targetID, fixture.expected.targetTitle)
+    await waitForTimelineStable(page)
+    const scroller = timelineScroller(page)
+    await scroller.evaluate((element) => {
+      element.scrollTop = element.scrollHeight
+    })
+    await waitForTimelineStable(page)
+
+    const spacer = scroller.locator('[data-timeline-row="bottom-spacer"]')
+    await expect(spacer).toBeVisible()
+    expect(await spacer.evaluate((element) => element.getBoundingClientRect().height)).toBe(64)
+    await expect
+      .poll(() => scroller.evaluate((element) => element.scrollHeight - element.clientHeight - element.scrollTop))
+      .toBeLessThanOrEqual(1)
+  })
+
+  test("paints cached session tabs at the latest message", async ({ page }) => {
+    await mockOpenCodeServer(page, {
+      sessions: fixture.sessions,
+      provider: fixture.provider,
+      directory: fixture.directory,
+      project: fixture.project,
+      pageMessages: (sessionID) => ({ items: fixture.messages[sessionID as keyof typeof fixture.messages] ?? [] }),
+    })
+    await configureSmokePage(page, fixture.directory)
+    await page.addInitScript(
+      ({ dirBase64, sourceID, targetID }) => {
+        localStorage.setItem(
+          "opencode.window.browser.dat:tabs",
+          JSON.stringify(
+            [sourceID, targetID].map((sessionId) => ({
+              type: "session",
+              server: "http://127.0.0.1:4096",
+              dirBase64,
+              sessionId,
+            })),
+          ),
+        )
+      },
+      { dirBase64: base64Encode(fixture.directory), sourceID: fixture.sourceID, targetID: fixture.targetID },
+    )
+
+    await page.goto(`/${base64Encode(fixture.directory)}/session/${fixture.targetID}`)
+    await expectSessionTitle(page, fixture.expected.targetTitle)
+    await switchTitlebarSession(page, fixture.sourceID, fixture.expected.sourceTitle)
+
+    const destination = fixture.messages[fixture.targetID].map((message) => message.info.id)
+    const last = fixture.expected.targetMessageIDs.at(-1)!
+    await page.evaluate(
+      ({ destination, last }) => {
+        const ids = new Set(destination)
+        const samples: Array<{ ids: string[]; last: boolean; bottomError?: number }> = []
+        const firstPaintNodes = new WeakSet<Node>()
+        let firstPaint = false
+        let removedFirstPaintNodes = 0
+        let running = true
+        new MutationObserver((records) => {
+          if (!firstPaint || !running) return
+          records.forEach((record) =>
+            record.removedNodes.forEach((node) => {
+              if (firstPaintNodes.has(node)) removedFirstPaintNodes += 1
+              if (!(node instanceof Element)) return
+              node.querySelectorAll("*").forEach((element) => {
+                if (firstPaintNodes.has(element)) removedFirstPaintNodes += 1
+              })
+            }),
+          )
+        }).observe(document.documentElement, { childList: true, subtree: true })
+        const sample = () => {
+          if (!running) return
+          setTimeout(() => {
+            if (!running) return
+            const root = [...document.querySelectorAll<HTMLElement>(".scroll-view__viewport")].find((element) =>
+              element.querySelector("[data-timeline-row]"),
+            )
+            if (root) {
+              const view = root.getBoundingClientRect()
+              const visible = [...root.querySelectorAll<HTMLElement>("[data-message-id]")]
+                .filter((element) => {
+                  const rect = element.getBoundingClientRect()
+                  return rect.bottom > view.top && rect.top < view.bottom
+                })
+                .map((element) => element.dataset.messageId!)
+                .filter((id) => ids.has(id))
+              const bottom = root
+                .querySelector<HTMLElement>('[data-timeline-row="bottom-spacer"]')
+                ?.getBoundingClientRect()
+              samples.push({ ids: visible, last: visible.includes(last), bottomError: bottom?.bottom - view.bottom })
+              if (!firstPaint && visible.includes(last) && Math.abs((bottom?.bottom ?? Infinity) - view.bottom) <= 1) {
+                firstPaint = true
+                root.querySelectorAll<HTMLElement>("[data-timeline-key]").forEach((row) => {
+                  const rect = row.getBoundingClientRect()
+                  if (rect.bottom <= view.top || rect.top >= view.bottom) return
+                  firstPaintNodes.add(row)
+                  row.querySelectorAll("*").forEach((element) => firstPaintNodes.add(element))
+                })
+              }
+            }
+            requestAnimationFrame(sample)
+          }, 0)
+        }
+        ;(
+          window as Window & {
+            __sessionTabPaint?: { samples: typeof samples; removed: () => number; stop: () => void }
+          }
+        ).__sessionTabPaint = {
+          samples,
+          removed: () => removedFirstPaintNodes,
+          stop: () => {
+            running = false
+          },
+        }
+        requestAnimationFrame(sample)
+      },
+      { destination, last },
+    )
+
+    await switchTitlebarSession(page, fixture.targetID, fixture.expected.targetTitle)
+    await page.waitForFunction(() =>
+      (
+        window as Window & { __sessionTabPaint?: { samples: Array<{ ids: string[] }> } }
+      ).__sessionTabPaint?.samples.some((sample) => sample.ids.length > 0),
+    )
+    await page.waitForTimeout(200)
+    const first = await page.evaluate(() => {
+      const probe = (
+        window as Window & {
+          __sessionTabPaint?: {
+            samples: Array<{ ids: string[]; last: boolean; bottomError?: number }>
+            removed: () => number
+            stop: () => void
+          }
+        }
+      ).__sessionTabPaint!
+      probe.stop()
+      return { first: probe.samples.find((sample) => sample.ids.length > 0), removed: probe.removed() }
+    })
+    expect(first.first?.last).toBe(true)
+    expect(Math.abs(first.first?.bottomError ?? Infinity)).toBeLessThanOrEqual(1)
+    expect(first.removed).toBe(0)
+  })
+
+  test("paints a cold session tab at the latest message", async ({ page }) => {
+    await mockOpenCodeServer(page, {
+      sessions: fixture.sessions,
+      provider: fixture.provider,
+      directory: fixture.directory,
+      project: fixture.project,
+      pageMessages: (sessionID) => ({ items: fixture.messages[sessionID as keyof typeof fixture.messages] ?? [] }),
+    })
+    await configureSmokePage(page, fixture.directory)
+    await page.addInitScript(
+      ({ dirBase64, sourceID, targetID }) => {
+        localStorage.setItem(
+          "opencode.window.browser.dat:tabs",
+          JSON.stringify(
+            [sourceID, targetID].map((sessionId) => ({
+              type: "session",
+              server: "http://127.0.0.1:4096",
+              dirBase64,
+              sessionId,
+            })),
+          ),
+        )
+      },
+      { dirBase64: base64Encode(fixture.directory), sourceID: fixture.sourceID, targetID: fixture.targetID },
+    )
+    await page.goto(`/${base64Encode(fixture.directory)}/session/${fixture.sourceID}`)
+    await expectSessionTitle(page, fixture.expected.sourceTitle)
+    const last = fixture.expected.targetMessageIDs.at(-1)!
+    const destination = fixture.messages[fixture.targetID].map((message) => message.info.id)
+    await page.evaluate(
+      ({ destination, last }) => {
+        const ids = new Set(destination)
+        const samples: Array<{ destination: boolean; last: boolean; bottomError?: number }> = []
+        const sample = () => {
+          const root = [...document.querySelectorAll<HTMLElement>(".scroll-view__viewport")].find((element) =>
+            element.querySelector("[data-timeline-row]"),
+          )
+          if (root) {
+            const view = root.getBoundingClientRect()
+            const spacer = root
+              .querySelector<HTMLElement>('[data-timeline-row="bottom-spacer"]')
+              ?.getBoundingClientRect()
+            const messages = [...root.querySelectorAll<HTMLElement>("[data-message-id]")].filter((element) => {
+              const rect = element.getBoundingClientRect()
+              return rect.bottom > view.top && rect.top < view.bottom
+            })
+            samples.push({
+              destination: messages.some((element) => ids.has(element.dataset.messageId!)),
+              last: messages.some((element) => element.dataset.messageId === last),
+              bottomError: spacer ? spacer.bottom - view.bottom : undefined,
+            })
+          }
+          requestAnimationFrame(() => setTimeout(sample, 0))
+        }
+        ;(window as Window & { __coldTabSamples?: typeof samples }).__coldTabSamples = samples
+        requestAnimationFrame(() => setTimeout(sample, 0))
+      },
+      { destination, last },
+    )
+
+    await switchTitlebarSession(page, fixture.targetID, fixture.expected.targetTitle)
+    await page.waitForFunction(() =>
+      (window as Window & { __coldTabSamples?: Array<{ destination: boolean }> }).__coldTabSamples?.some(
+        (sample) => sample.destination,
+      ),
+    )
+    const result = await page.evaluate(() => {
+      const samples = (
+        window as Window & {
+          __coldTabSamples?: Array<{ destination: boolean; last: boolean; bottomError?: number }>
+        }
+      ).__coldTabSamples!
+      return samples.find((sample) => sample.destination)!
+    })
+    expect(result.last).toBe(true)
+    expect(Math.abs(result.bottomError ?? Infinity)).toBeLessThanOrEqual(1)
+  })
+
+  test("renders seeded timeline in order while paging through history", async ({ page }) => {
+    const errors = trackPageErrors(page)
+    await mockOpenCodeServer(page, {
+      sessions: fixture.sessions,
+      provider: fixture.provider,
+      directory: fixture.directory,
+      project: fixture.project,
+      pageMessages,
+    })
+    await configureSmokePage(page, fixture.directory)
+
+    await selectHomeProject(page, fixture.project.name)
+    await navigateToSession(page, fixture.directory, fixture.sourceID, fixture.expected.sourceTitle)
+    await expectSessionReady(page)
+    await navigateToSession(page, fixture.directory, fixture.targetID, fixture.expected.targetTitle)
+    const expectedPartIDs = fixture.expected.targetPartIDs
+    const expectedMessageIDs = fixture.expected.targetMessageIDs
+    await expectSessionTimelineReady(page, expectedPartIDs, expectedMessageIDs, errors)
+    await expectCanScrollToStart(page, expectedPartIDs, expectedMessageIDs, errors)
+
+    const shell = page.locator(`[data-timeline-part-id="${fixture.expected.expandedShellPartID}"]`)
+    const shellTrigger = shell.locator('[data-slot="collapsible-trigger"]')
+    const shellSubtitle = shell.locator('[data-slot="basic-tool-tool-subtitle"]')
+    await expect(shellSubtitle).toHaveCount(0)
+    await expect(shell.locator('[data-slot="bash-pre"]')).toContainText("$ bun typecheck")
+    await shellTrigger.click()
+    await expect(shellTrigger).toHaveAttribute("aria-expanded", "false")
+    await expect(shellSubtitle).toHaveText("bun typecheck")
+    await shellTrigger.click()
+    await expect(shellTrigger).toHaveAttribute("aria-expanded", "true")
+    await expect(shellSubtitle).toHaveCount(0)
+  })
+})
+
+async function configureSmokePage(page: Page, directory: string) {
+  await page.addInitScript(() => {
+    localStorage.setItem(
+      "settings.v3",
+      JSON.stringify({
+        general: {
+          editToolPartsExpanded: true,
+          shellToolPartsExpanded: true,
+          showReasoningSummaries: true,
+        },
+      }),
+    )
+  })
+
+  await page.addInitScript((directory) => {
+    localStorage.setItem(
+      "opencode.global.dat:server",
+      JSON.stringify({
+        projects: {
+          local: [{ worktree: directory, expanded: true }],
+        },
+        lastProject: {
+          local: directory,
+        },
+      }),
+    )
+  }, directory)
+
+  await page.addInitScript(() => {
+    const smoke = window as SmokeWindow
+    smoke.__timelineSmokeErrorToasts = []
+    smoke.__timelineSmokeForbiddenText = []
+    const partSelector = "[data-timeline-part-id], [data-timeline-part-ids]"
+    const idsOf = (el: HTMLElement) =>
+      [el.dataset.timelinePartId, ...(el.dataset.timelinePartIds?.split(",") ?? [])].filter((id): id is string => !!id)
+
+    smoke.__timelineSmokeState = () => {
+      const scroller = [...document.querySelectorAll<HTMLElement>(".scroll-view__viewport")].find((el) =>
+        el.querySelector("[data-timeline-row], [data-session-title]"),
+      )
+      if (!scroller) {
+        return {
+          ids: [],
+          visibleIds: [],
+          messageIds: [],
+          visibleMessageIds: [],
+          topVisibleId: undefined,
+          signature: "",
+          scrollTop: 0,
+          scrollHeight: 0,
+          clientHeight: 0,
+          errorToasts: smoke.__timelineSmokeErrorToasts ?? [],
+          forbiddenText: smoke.__timelineSmokeForbiddenText ?? [],
+        }
+      }
+
+      const ids: string[] = []
+      const visibleIds: string[] = []
+      const scrollerRect = scroller.getBoundingClientRect()
+      let topVisibleId: string | undefined
+      for (const el of scroller.querySelectorAll<HTMLElement>(partSelector)) {
+        const next = idsOf(el)
+        ids.push(...next)
+
+        const rect = el.getBoundingClientRect()
+        if (rect.bottom >= scrollerRect.top && rect.top <= scrollerRect.bottom) {
+          if (!topVisibleId) topVisibleId = next[0]
+          visibleIds.push(...next)
+        }
+      }
+
+      const messageIds: string[] = []
+      const visibleMessageIds: string[] = []
+      const rows = [...scroller.querySelectorAll<HTMLElement>("[data-message-id]")].map((el) => {
+        const rect = el.getBoundingClientRect()
+        const id = el.dataset.messageId
+        if (id) {
+          messageIds.push(id)
+          if (rect.bottom >= scrollerRect.top && rect.top <= scrollerRect.bottom) visibleMessageIds.push(id)
+        }
+        return {
+          id,
+          top: Math.round(rect.top),
+          bottom: Math.round(rect.bottom),
+        }
+      })
+      const signature = JSON.stringify({
+        top: Math.round(scroller.scrollTop),
+        height: Math.round(scroller.scrollHeight),
+        rows,
+        ids,
+      })
+
+      return {
+        ids,
+        visibleIds,
+        messageIds,
+        visibleMessageIds,
+        topVisibleId,
+        signature,
+        scrollTop: Math.round(scroller.scrollTop),
+        scrollHeight: Math.round(scroller.scrollHeight),
+        clientHeight: Math.round(scroller.clientHeight),
+        errorToasts: smoke.__timelineSmokeErrorToasts ?? [],
+        forbiddenText: smoke.__timelineSmokeForbiddenText ?? [],
+      }
+    }
+    let recordFrame: number | undefined
+    const record = () => {
+      for (const toast of document.querySelectorAll<HTMLElement>('[data-component="toast"][data-variant="error"]')) {
+        const text = toast.textContent?.trim()
+        if (text && !smoke.__timelineSmokeErrorToasts!.includes(text)) smoke.__timelineSmokeErrorToasts!.push(text)
+      }
+      const text = document.body?.textContent ?? ""
+      for (const value of ["Load details", "Show earlier steps"]) {
+        if (text.includes(value) && !smoke.__timelineSmokeForbiddenText!.includes(value)) {
+          smoke.__timelineSmokeForbiddenText!.push(value)
+        }
+      }
+    }
+    const start = () => {
+      const root = document.documentElement ?? document.body
+      if (!root) return
+      new MutationObserver(() => {
+        if (recordFrame) return
+        recordFrame = requestAnimationFrame(() => {
+          recordFrame = undefined
+          record()
+        })
+      }).observe(root, { childList: true, subtree: true })
+      record()
+    }
+    if (document.documentElement ?? document.body) start()
+    else document.addEventListener("DOMContentLoaded", start, { once: true })
+  })
+}
+
+async function expectCanScrollToStart(
+  page: Page,
+  expectedPartIDs: string[],
+  expectedMessageIDs: string[],
+  errors: string[],
+) {
+  await pointAtTimeline(page)
+  const seenParts = new Set<string>()
+  const seenMessages = new Set<string>()
+  const samples: TraversalSample[] = []
+  let current = await timelineState(page)
+  let unchangedAtTop = 0
+
+  for (let attempt = 0; attempt < 600; attempt++) {
+    collectSeen(current, seenParts, seenMessages)
+    samples.push(sampleTraversal(current, seenParts.size, seenMessages.size))
+    expectNoSmokeErrors(errors, current.errorToasts, current.forbiddenText)
+    expectOrderedIDs(expectedPartIDs, current.ids, "mounted part")
+    expectOrderedIDs(expectedPartIDs, current.visibleIds, "visible part")
+    expectOrderedIDs(expectedMessageIDs, unique(current.messageIds), "mounted message")
+    expectOrderedIDs(expectedMessageIDs, unique(current.visibleMessageIds), "visible message")
+
+    if (
+      current.scrollTop <= 1 &&
+      seenParts.size === expectedPartIDs.length &&
+      seenMessages.size === expectedMessageIDs.length
+    ) {
+      expectCompleteScroll(current, expectedPartIDs, expectedMessageIDs, seenParts, seenMessages, samples)
+      return
+    }
+
+    const before = current
+    const changed = await scrollTimelineUp(page, current)
+    current = await timelineState(page)
+    if (!changed && current.signature === before.signature && current.scrollTop <= 1) unchangedAtTop++
+    else unchangedAtTop = 0
+    if (unchangedAtTop >= 2) break
+  }
+
+  collectSeen(current, seenParts, seenMessages)
+  samples.push(sampleTraversal(current, seenParts.size, seenMessages.size))
+  expectCompleteScroll(current, expectedPartIDs, expectedMessageIDs, seenParts, seenMessages, samples)
+}
+
+async function timelineState(page: Page) {
+  return page.evaluate(
+    () =>
+      (window as SmokeWindow).__timelineSmokeState?.() ?? {
+        ids: [],
+        visibleIds: [],
+        messageIds: [],
+        visibleMessageIds: [],
+        topVisibleId: undefined,
+        signature: "",
+        scrollTop: 0,
+        scrollHeight: 0,
+        clientHeight: 0,
+        errorToasts: [],
+        forbiddenText: [],
+      },
+  )
+}
+
+function timelineScroller(page: Page) {
+  return page.locator(".scroll-view__viewport", { has: page.locator("[data-timeline-row]") })
+}
+
+async function pointAtTimeline(page: Page) {
+  const box = await timelineScroller(page).boundingBox()
+  if (!box) throw new Error("Timeline scroller is not visible")
+  await page.mouse.move(box.x + box.width / 2, box.y + box.height / 2)
+}
+
+async function scrollTimelineUp(page: Page, before: SmokeState) {
+  return page.evaluate(
+    (prev) =>
+      new Promise<boolean>((resolve) => {
+        const scroller = [...document.querySelectorAll<HTMLElement>(".scroll-view__viewport")].find((el) =>
+          el.querySelector("[data-timeline-row], [data-session-title]"),
+        )
+        if (!scroller) {
+          resolve(false)
+          return
+        }
+
+        scroller.dispatchEvent(new WheelEvent("wheel", { bubbles: true, cancelable: true, deltaY: -1, deltaMode: 0 }))
+        scroller.scrollTop = Math.max(0, scroller.scrollTop - Math.max(80, Math.round(scroller.clientHeight * 0.45)))
+
+        const read = () => (window as SmokeWindow).__timelineSmokeState?.().signature ?? ""
+        let frames = 0
+        let stableFrames = 0
+        let last = ""
+        let changed = false
+        const check = () => {
+          const current = read()
+          if (current !== prev) changed = true
+          if (current === last) stableFrames++
+          else {
+            stableFrames = 0
+            last = current
+          }
+          if (changed && stableFrames >= 2) {
+            resolve(true)
+            return
+          }
+          frames++
+          if (frames >= 30) {
+            resolve(changed)
+            return
+          }
+          requestAnimationFrame(check)
+        }
+        requestAnimationFrame(check)
+      }),
+    before.signature,
+  )
+}
+
+function expectOrderedIDs(expected: string[], actual: string[], label: string) {
+  expect(actual.length, `${label} ids should not be empty`).toBeGreaterThan(0)
+  const actualSet = new Set(actual)
+  expect(actual, `${label} ids`).toEqual(expected.filter((id) => actualSet.has(id)))
+}
+
+function unique(values: string[]) {
+  return values.filter((value, index) => values.indexOf(value) === index)
+}
+
+function collectSeen(state: SmokeState, seenParts: Set<string>, seenMessages: Set<string>) {
+  for (const id of state.ids) seenParts.add(id)
+  for (const id of state.visibleIds) seenParts.add(id)
+  for (const id of state.messageIds) seenMessages.add(id)
+  for (const id of state.visibleMessageIds) seenMessages.add(id)
+}
+
+type TraversalSample = ReturnType<typeof sampleTraversal>
+
+function sampleTraversal(state: SmokeState, seenParts: number, seenMessages: number) {
+  return {
+    seenParts,
+    seenMessages,
+    mounted: state.ids.length,
+    visible: state.visibleIds.length,
+    mountedMessages: unique(state.messageIds).length,
+    visibleMessages: unique(state.visibleMessageIds).length,
+    top: state.scrollTop,
+    height: state.scrollHeight,
+    first: state.ids[0],
+    last: state.ids.at(-1),
+    topVisible: state.topVisibleId,
+    visibleFirst: state.visibleIds[0],
+    visibleLast: state.visibleIds.at(-1),
+  }
+}
+
+function sampleSummary(samples: TraversalSample[]) {
+  return samples
+    .filter((_, index) => index % Math.max(1, Math.floor(samples.length / 8)) === 0 || index === samples.length - 1)
+    .map(
+      (sample, index) =>
+        `${index}: seenParts=${sample.seenParts} seenMessages=${sample.seenMessages} mounted=${sample.mounted}/${sample.mountedMessages} visible=${sample.visible}/${sample.visibleMessages} top=${sample.top}/${sample.height} first=${sample.first} last=${sample.last} topVisible=${sample.topVisible} visible=${sample.visibleFirst}..${sample.visibleLast}`,
+    )
+    .join("\n")
+}
+
+async function waitForTimelineStable(page: Page) {
+  await page.waitForFunction(
+    () =>
+      new Promise<boolean>((resolve) => {
+        requestAnimationFrame(() => {
+          const a = (window as SmokeWindow).__timelineSmokeState?.().signature ?? ""
+          requestAnimationFrame(() => {
+            const b = (window as SmokeWindow).__timelineSmokeState?.().signature ?? ""
+            requestAnimationFrame(() =>
+              resolve(!!a && a === b && b === ((window as SmokeWindow).__timelineSmokeState?.().signature ?? "")),
+            )
+          })
+        })
+      }),
+  )
+}
+
+async function expectSessionTimelineReady(
+  page: Page,
+  expectedPartIDs: string[],
+  expectedMessageIDs: string[],
+  errors: string[],
+) {
+  await waitForTimelineStable(page)
+  for (const text of forbiddenText) await expect(page.getByText(text)).toHaveCount(0)
+  const currentState = await timelineState(page)
+  expectNoSmokeErrors(errors, currentState.errorToasts, currentState.forbiddenText)
+  expectOrderedIDs(expectedPartIDs, currentState.ids, "mounted part")
+  expectOrderedIDs(expectedPartIDs, currentState.visibleIds, "visible part")
+  expectOrderedIDs(expectedMessageIDs, unique(currentState.messageIds), "mounted message")
+  expectOrderedIDs(expectedMessageIDs, unique(currentState.visibleMessageIds), "visible message")
+}
+
+function expectCompleteScroll(
+  state: SmokeState,
+  expectedPartIDs: string[],
+  expectedMessageIDs: string[],
+  seenParts: Set<string>,
+  seenMessages: Set<string>,
+  samples: TraversalSample[],
+) {
+  expect(state.scrollTop, `timeline should reach the start\n${sampleSummary(samples)}`).toBeLessThanOrEqual(1)
+  expect(
+    expectedPartIDs.filter((id) => !seenParts.has(id)),
+    `missing visible timeline parts\n${sampleSummary(samples)}`,
+  ).toEqual([])
+  expect(
+    expectedMessageIDs.filter((id) => !seenMessages.has(id)),
+    `missing visible messages\n${sampleSummary(samples)}`,
+  ).toEqual([])
+  expect(new Set(expectedPartIDs).size).toBe(expectedPartIDs.length)
+  expect(new Set(expectedMessageIDs).size).toBe(expectedMessageIDs.length)
+  expect(expectedPartIDs.length).toBe(331)
+}
+
+async function selectHomeProject(page: Page, projectName: string) {
+  await page.goto("/")
+  const row = page
+    .locator('[data-component="home-project-row"]')
+    .filter({ hasText: new RegExp(projectName, "i") })
+    .first()
+  await expectAppVisible(row)
+  await row.click()
+  await expect(row).toHaveAttribute("data-selected", "", { timeout: APP_READY_TIMEOUT })
+  await expect(page).toHaveURL(/\/$/)
+}
+
+async function navigateToSession(page: Page, directory: string, sessionId: string, expectedTitle: string) {
+  await page.goto(`/${base64Encode(directory)}/session/${sessionId}`)
+  await expectSessionTitle(page, expectedTitle)
+}
+
+async function switchTitlebarSession(page: Page, sessionID: string, title: string) {
+  const href = `/server/${base64Encode(fixture.serverKey)}/session/${sessionID}`
+  const tab = page.locator(`[data-slot="titlebar-tabs"] a[href="${href}"]`).first()
+  await expect(tab).toBeVisible()
+  await tab.click()
+  await expectSessionTitle(page, title)
+}
+
+async function expectSessionReady(page: Page) {
+  await expectAppVisible(page.getByRole("textbox", { name: "Prompt" }))
+}