feat(app): make session timelines much faster AND without flicker or scroll jumps (#32331)

2026-06-16 18:53:57 +02:00
parent e772664389
commit 3b811bd019
49 changed files with 2822 additions and 843 deletions
@@ -147,7 +147,8 @@ test.describe("regression: session timeline local row state", () => {

    const wrapper = page.locator(`[data-timeline-part-id="${editPartID}"]`).first()
    await expectAppVisible(wrapper)
-    await expectAppVisible(wrapper.locator('[data-component="file"][data-mode="diff"]').first())
+    const file = wrapper.locator('[data-component="file"][data-mode="diff"]').first()
+    await expectAppVisible(file)
    await markDiffProbe(page)

    events.push({
@@ -159,7 +160,15 @@ test.describe("regression: session timeline local row state", () => {
    })

    await expect(page.locator(`[data-timeline-part-id="${textPartID}"]`).first()).toBeVisible({ timeout: 10_000 })
-    expect(await readDiffProbe(page)).toEqual({ fileMarker: "before", shadowRoots: 0, toolMarker: "before" })
+    const siblingProbe = await readDiffProbe(page)
+    expect(siblingProbe).toEqual({
+      fileMarker: "before",
+      frameMarker: "before",
+      rowKey: `assistant-part:${userMessageID}:part:${assistantMessageID}:${editPartID}`,
+      rowMarker: "before",
+      shadowRoots: 0,
+      toolMarker: "before",
+    })

    await markDiffProbe(page)
    events.push({
@@ -173,7 +182,72 @@ test.describe("regression: session timeline local row state", () => {
    await expect(wrapper.locator('[data-slot="diff-changes-additions"]').filter({ hasText: "+2" }).first()).toBeVisible(
      { timeout: 10_000 },
    )
-    expect(await readDiffProbe(page)).toEqual({ fileMarker: "before", shadowRoots: 0, toolMarker: "before" })
+    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)
  })
 })

@@ -247,10 +321,16 @@ async function markDiffProbe(page: Page) {
    .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()
    })
 }
@@ -262,10 +342,15 @@ async function readDiffProbe(page: Page) {
    .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,
      }
    })
 }
@@ -300,14 +385,19 @@ function readExpanded(element: Element) {
  return !!content && content.getBoundingClientRect().height > 0
 }

-async function mockServer(page: Page, events: EventPayload[]) {
+async function mockServer(
+  page: Page,
+  events: EventPayload[],
+  messages = [userMessage, assistantMessage],
+) {
  await mockOpenCodeServer(page, {
    directory,
    project: project(),
    provider: provider(),
    sessions: [session()],
-    pageMessages: () => ({ items: [userMessage, assistantMessage] }),
-    events: () => events.splice(0),
+    pageMessages: () => ({ items: messages }),
+    events: () => events.splice(0, 1),
+    eventRetry: 16,
  })
 }

@@ -32,8 +32,6 @@ test.describe("regression: session timeline context group resize", () => {
    const samples = await sampleExpansion(page)
    const visibleOverlap = samples.filter((sample) => sample.frame >= 1 && sample.overlap > 0.5)

-    console.log("context resize samples", JSON.stringify(samples, null, 2))
-
    expect(samples[0]?.overlap).toBe(0)
    expect(visibleOverlap).toEqual([])
    expect(samples.at(-1)?.expanded).toBe("true")
@@ -115,13 +113,15 @@ async function sampleExpansion(page: Page) {

        let frame = 1
        const tick = () => {
-          capture(frame, "raf")
-          frame += 1
-          if (frame > 8) {
-            resolve(samples)
-            return
-          }
-          requestAnimationFrame(tick)
+          setTimeout(() => {
+            capture(frame, "painted")
+            frame += 1
+            if (frame > 8) {
+              resolve(samples)
+              return
+            }
+            requestAnimationFrame(tick)
+          }, 0)
        }
        requestAnimationFrame(tick)
      }),
@@ -30,6 +30,271 @@ type SmokeWindow = Window & {
 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 = ["prt_user_text_smoke_0032", "prt_text_2_smoke_0032", "prt_tool_apply_patch_8_smoke_0032"]
+    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.global.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.global.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, {
@@ -427,6 +692,14 @@ async function navigateToSession(page: Page, directory: string, sessionId: strin
  await expectSessionTitle(page, expectedTitle)
 }

+async function switchTitlebarSession(page: Page, sessionID: string, title: string) {
+  const href = `/${base64Encode(fixture.directory)}/session/${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: /Ask anything/i }))
 }
@@ -18,7 +18,10 @@ export interface MockServerConfig {
  project: unknown
  sessions: ({ id: string } & Record<string, unknown>)[]
  pageMessages: (sessionId: string, limit: number, before?: string) => { items: unknown[]; cursor?: string }
+  messageDelay?: number
+  onMessages?: (input: { sessionID: string; before?: string; phase: "start" | "end" }) => void
  events?: () => unknown[]
+  eventRetry?: number
 }

 export async function mockOpenCodeServer(page: Page, config: MockServerConfig) {
@@ -44,7 +47,7 @@ export async function mockOpenCodeServer(page: Page, config: MockServerConfig) {
    if (url.port !== targetPort) return route.fallback()

    const path = url.pathname
-    if (path === "/global/event" || path === "/event") return sse(route, config.events?.())
+    if (path === "/global/event" || path === "/event") return sse(route, config.events?.(), config.eventRetry)
    if (path === "/global/health") return json(route, { healthy: true })
    if (emptyObject.has(path)) return json(route, {})
    if (emptyList.has(path)) return json(route, [])
@@ -60,9 +63,12 @@ export async function mockOpenCodeServer(page: Page, config: MockServerConfig) {

    const messagesMatch = path.match(/^\/session\/([^/]+)\/message$/)
    if (messagesMatch) {
-      const limit = Number(url.searchParams.get("limit") ?? 80)
      const before = url.searchParams.get("before") ?? undefined
+      config.onMessages?.({ sessionID: messagesMatch[1], before, phase: "start" })
+      if (config.messageDelay) await new Promise((resolve) => setTimeout(resolve, config.messageDelay))
+      const limit = Number(url.searchParams.get("limit") ?? 80)
      const pageData = config.pageMessages(messagesMatch[1], limit, before)
+      config.onMessages?.({ sessionID: messagesMatch[1], before, phase: "end" })
      return json(route, pageData.items, pageData.cursor ? { "x-next-cursor": pageData.cursor } : undefined)
    }

@@ -83,10 +89,10 @@ function json(route: Route, body: unknown, headers?: Record<string, string>) {
  })
 }

-function sse(route: Route, events?: unknown[]) {
+function sse(route: Route, events?: unknown[], retry?: number) {
  return route.fulfill({
    status: 200,
    contentType: "text/event-stream",
-    body: events?.map((event) => `data: ${JSON.stringify(event)}\n\n`).join("") || ": ok\n\n",
+    body: `${retry === undefined ? "" : `retry: ${retry}\n\n`}${events?.map((event) => `data: ${JSON.stringify(event)}\n\n`).join("") || ": ok\n\n"}`,
  })
 }