fix(chat): defer turn diff details and localize resolution times

2026-09-29 08:03:20 +00:00 · 2026-09-07 00:06:35 -07:00
parent edaa1bc8a6
commit 35fe0cfc90
15 changed files with 585 additions and 152 deletions
@@ -2,10 +2,13 @@

 import '@testing-library/jest-dom/vitest'

-import { cleanup, render } from '@testing-library/react'
+import { cleanup, fireEvent, render, screen } from '@testing-library/react'
 import { afterEach, describe, expect, it, vi } from 'vitest'
 import type * as NativeChatProseModule from './native-chat-prose'
 import type { NativeChatMessage } from '../../../../shared/native-chat-types'
+import { projectStructuredAgentSessionMessages } from '../../../../shared/structured-agent-session-message-projection'
+import type { AgentJournalRenderItem } from '../../../../shared/agent-session-journal-types'
+import type * as UnifiedPatchModule from '../../../../shared/native-chat-unified-patch'
 import type { NativeChatLiveSession } from './use-native-chat-live-session'

 // Counting real per-row work rather than a render counter: a future refactor could keep the
@@ -22,6 +25,22 @@ vi.mock('./native-chat-prose', async (importOriginal) => {
  }
 })

+const patchCalls = vi.hoisted(() => ({ detailed: 0, summary: 0 }))
+vi.mock('../../../../shared/native-chat-unified-patch', async (importOriginal) => {
+  const actual = await importOriginal<typeof UnifiedPatchModule>()
+  return {
+    ...actual,
+    editLinesFromUnifiedPatch: (...args: Parameters<typeof actual.editLinesFromUnifiedPatch>) => {
+      patchCalls.detailed += 1
+      return actual.editLinesFromUnifiedPatch(...args)
+    },
+    summarizeUnifiedPatch: (...args: Parameters<typeof actual.summarizeUnifiedPatch>) => {
+      patchCalls.summary += 1
+      return actual.summarizeUnifiedPatch(...args)
+    }
+  }
+})
+
 const { NativeChatMessageList } = await import('./NativeChatMessageList')

 afterEach(cleanup)
@@ -88,4 +107,68 @@ describe('native chat transcript re-render cost during a streaming turn', () =>
    // rows keep their block identity, so only the streaming tail should rebuild.
    expect(perFrame).toBeLessThan(TRANSCRIPT_LENGTH / 10)
  })
+
+  it('keeps structured diff rows lazy and reuses counts across journal updates', () => {
+    patchCalls.detailed = 0
+    patchCalls.summary = 0
+    const user: AgentJournalRenderItem = {
+      itemId: 'user',
+      revision: 1,
+      sequence: 1,
+      observedAt: 1000,
+      body: { kind: 'message', role: 'user', blocks: [{ type: 'text', text: 'Edit a file' }] }
+    }
+    const diff: AgentJournalRenderItem = {
+      itemId: 'diff',
+      revision: 1,
+      sequence: 2,
+      observedAt: 2000,
+      body: {
+        kind: 'diff',
+        path: 'src/a.ts',
+        patch: {
+          head: '@@ -1 +1 @@\n-old\n+new',
+          truncated: false,
+          digest: 'fixture',
+          byteLength: 25
+        }
+      }
+    }
+    const view = (items: AgentJournalRenderItem[]) => (
+      <NativeChatMessageList
+        session={sessionWith(projectStructuredAgentSessionMessages(items, [], []))}
+        journalItems={items}
+        isWorking={false}
+        expandSignal={false}
+        fontScale={1}
+      />
+    )
+    const { rerender } = render(view([user, diff]))
+    expect(patchCalls).toEqual({ summary: 1, detailed: 0 })
+    for (let frame = 0; frame < 20; frame += 1) {
+      rerender(
+        view([
+          user,
+          diff,
+          {
+            itemId: 'tail',
+            revision: frame + 1,
+            sequence: 3,
+            observedAt: 3000,
+            body: {
+              kind: 'message',
+              role: 'assistant',
+              blocks: [{ type: 'text', text: `Token ${frame}` }]
+            }
+          }
+        ])
+      )
+    }
+    expect(patchCalls).toEqual({ summary: 1, detailed: 0 })
+    fireEvent.click(screen.getByRole('button', { name: /1 changed file/ }))
+    expect(patchCalls.detailed).toBe(0)
+    fireEvent.click(screen.getByRole('button', { name: /src\/a.ts/ }))
+    expect(patchCalls).toEqual({ summary: 1, detailed: 1 })
+    expect(screen.getByText('new')).toBeInTheDocument()
+  })
 })
@@ -80,6 +80,8 @@ describe('turn history presentation', () => {
    expect(screen.getByText('after')).toBeInTheDocument()
    expect(screen.getByText('before')).toBeInTheDocument()
    expect(scrollTo).toHaveBeenCalled()
+    fireEvent.click(screen.getByRole('button', { name: /1× Diff/ }))
+    expect(screen.queryByText('Edited file')).toBeNull()
    fireEvent.click(header)
    expect(header).toHaveAttribute('aria-expanded', 'false')
    fireEvent.click(header)
@@ -0,0 +1,61 @@
+// @vitest-environment happy-dom
+import '@testing-library/jest-dom/vitest'
+import { act, cleanup, render, screen } from '@testing-library/react'
+import { afterEach, describe, expect, it } from 'vitest'
+import { i18n } from '@/i18n/i18n'
+import { NativeChatMessageTimestamp } from './NativeChatMessageTimestamp'
+
+afterEach(async () => {
+  cleanup()
+  await i18n.changeLanguage('en')
+})
+
+describe('NativeChatMessageTimestamp', () => {
+  it.each([null, Number.NaN, Infinity, -Infinity, 8.64e15 + 1])(
+    'omits missing or invalid time %s',
+    (timestamp) => {
+      const { container } = render(<NativeChatMessageTimestamp timestamp={timestamp} focusable />)
+      expect(container).toBeEmptyDOMElement()
+    }
+  )
+
+  it.each([0, Date.parse('2026-09-06T19:04:05Z')])(
+    'renders absolute time and full metadata for %s',
+    (timestamp) => {
+      render(<NativeChatMessageTimestamp timestamp={timestamp} />)
+      const time = screen.getByRole('time')
+      expect(time).toHaveAttribute('datetime', new Date(timestamp).toISOString())
+      expect(time).toHaveTextContent(
+        new Intl.DateTimeFormat('en', { hour: 'numeric', minute: '2-digit' }).format(timestamp)
+      )
+      expect(time).toHaveAccessibleName(
+        new Intl.DateTimeFormat('en', { dateStyle: 'full', timeStyle: 'long' }).format(timestamp)
+      )
+      expect(time).not.toHaveAttribute('tabindex')
+    }
+  )
+
+  it('provides a focus target only when requested for user metadata', () => {
+    render(<NativeChatMessageTimestamp timestamp={0} focusable />)
+    const time = screen.getByRole('time')
+    time.focus()
+    expect(time).toHaveFocus()
+    expect(time).toHaveAttribute('tabindex', '0')
+  })
+
+  it('updates settled time when the UI language changes without a parent rerender', async () => {
+    const timestamp = Date.parse('2026-09-06T19:04:05Z')
+    render(<NativeChatMessageTimestamp timestamp={timestamp} />)
+    await act(async () => {
+      await i18n.changeLanguage('fr')
+    })
+    const time = screen.getByRole('time')
+    expect(time).toHaveTextContent(
+      new Intl.DateTimeFormat('fr', { hour: 'numeric', minute: '2-digit' }).format(timestamp)
+    )
+    expect(time).toHaveAccessibleName(
+      new Intl.DateTimeFormat('fr', { dateStyle: 'full', timeStyle: 'long' }).format(timestamp)
+    )
+    expect(time).toHaveAttribute('datetime', new Date(timestamp).toISOString())
+  })
+})
@@ -0,0 +1,55 @@
+import { useTranslation } from 'react-i18next'
+import { getIntlLocale } from '@/i18n/i18n'
+import { cn } from '@/lib/utils'
+
+let cached: {
+  locale: string
+  time: Intl.DateTimeFormat
+  full: Intl.DateTimeFormat
+} | null = null
+
+function getTimestampFormatters(): NonNullable<typeof cached> {
+  const locale = getIntlLocale()
+  if (!cached || cached.locale !== locale) {
+    cached = {
+      locale,
+      time: new Intl.DateTimeFormat(locale, { hour: 'numeric', minute: '2-digit' }),
+      full: new Intl.DateTimeFormat(locale, { dateStyle: 'full', timeStyle: 'long' })
+    }
+  }
+  return cached
+}
+
+export function NativeChatMessageTimestamp({
+  timestamp,
+  focusable = false,
+  className
+}: {
+  timestamp: number | null
+  focusable?: boolean
+  className?: string
+}): React.JSX.Element | null {
+  useTranslation()
+  if (timestamp === null) {
+    return null
+  }
+  const date = new Date(timestamp)
+  if (Number.isNaN(date.getTime())) {
+    return null
+  }
+  const formatters = getTimestampFormatters()
+
+  return (
+    <time
+      dateTime={date.toISOString()}
+      aria-label={formatters.full.format(date)}
+      tabIndex={focusable ? 0 : undefined}
+      className={cn(
+        'rounded-md text-xs whitespace-nowrap text-muted-foreground tabular-nums focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring',
+        className
+      )}
+    >
+      {formatters.time.format(date)}
+    </time>
+  )
+}
@@ -1,7 +1,8 @@
 // @vitest-environment happy-dom
 import '@testing-library/jest-dom/vitest'
-import { cleanup, render, screen } from '@testing-library/react'
+import { act, cleanup, render, screen } from '@testing-library/react'
 import { afterEach, describe, expect, it } from 'vitest'
+import { i18n } from '@/i18n/i18n'
 import type { AgentJournalQuestionItem } from '../../../../shared/agent-session-journal-types'
 import { encodeAgentSessionQuestionAnswers } from '../../../../shared/agent-session-question-answer'
 import { NativeChatResolutionReceipt } from './NativeChatResolutionReceipt'
@@ -10,7 +11,10 @@ import {
  type NativeChatResolvedPrompt
 } from './native-chat-resolution-receipt'

-afterEach(cleanup)
+afterEach(async () => {
+  cleanup()
+  await i18n.changeLanguage('en')
+})
 const approval: NativeChatResolvedPrompt = {
  kind: 'approval',
  title: 'Run command?',
@@ -28,6 +32,19 @@ const approval: NativeChatResolvedPrompt = {
 }

 describe('resolution receipts', () => {
+  it('localizes the resolved time when the UI language changes', async () => {
+    render(<NativeChatResolutionReceipt body={approval} />)
+    await act(async () => {
+      await i18n.changeLanguage('fr')
+    })
+    expect(screen.getByRole('time')).toHaveTextContent(
+      new Intl.DateTimeFormat('fr', { hour: 'numeric', minute: '2-digit' }).format(1000)
+    )
+    expect(screen.getByRole('time')).toHaveAccessibleName(
+      new Intl.DateTimeFormat('fr', { dateStyle: 'full', timeStyle: 'long' }).format(1000)
+    )
+  })
+
  it.each([
    ['yes', 'Allow once'],
    ['no', 'Deny']
@@ -1,5 +1,5 @@
 import { translate } from '@/i18n/i18n'
-import { formatShortTimeAgo } from '@/lib/short-time-ago'
+import { NativeChatMessageTimestamp } from './NativeChatMessageTimestamp'
 import {
  nativeChatReceiptAnswers,
  type NativeChatResolvedPrompt
@@ -26,7 +26,7 @@ export function NativeChatResolutionReceipt({
        <p className="line-clamp-3 whitespace-pre-wrap break-words">{body.detail}</p>
      ) : null}
      {answers.map((answer, index) => (
-        <div key={index}>
+        <div key={body.kind === 'question' ? (body.questions?.[index]?.id ?? 'answer') : 'answer'}>
          {answer.question ? <p>{answer.question}</p> : null}
          <p className="line-clamp-3 whitespace-pre-wrap break-words">
            {answer.answer ??
@@ -54,12 +54,7 @@ export function NativeChatResolutionReceipt({
                })}
          </span>
        ) : null}
-        {resolution.resolvedAt !== null &&
-        Number.isFinite(new Date(resolution.resolvedAt).getTime()) ? (
-          <time dateTime={new Date(resolution.resolvedAt).toISOString()}>
-            {formatShortTimeAgo(resolution.resolvedAt)}
-          </time>
-        ) : null}
+        <NativeChatMessageTimestamp timestamp={resolution.resolvedAt} />
      </div>
    </div>
  )
@@ -1,4 +1,4 @@
-import { useEffect, useMemo, useState } from 'react'
+import { useMemo, useState } from 'react'
 import { Check, ChevronRight } from 'lucide-react'
 import { cn } from '@/lib/utils'
 import { translate } from '@/i18n/i18n'
@@ -152,15 +152,23 @@ export function NativeChatToolRun({
  activeTurnIsWorking?: boolean
  structuredActivityUi?: boolean
 }): React.JSX.Element | null {
-  const [open, setOpen] = useState(expandOverride ?? expandSignal)
-  // Re-sync when the global toolbar toggle flips.
-  useEffect(() => setOpen(expandOverride ?? expandSignal), [expandOverride, expandSignal])
-
-  useEffect(() => {
-    if (revealedDiff) {
+  const [open, setOpen] = useState(revealedDiff ? true : (expandOverride ?? expandSignal))
+  const [controls, setControls] = useState({ expandOverride, expandSignal, revealedDiff })
+  if (
+    controls.expandOverride !== expandOverride ||
+    controls.expandSignal !== expandSignal ||
+    controls.revealedDiff !== revealedDiff
+  ) {
+    setControls({ expandOverride, expandSignal, revealedDiff })
+    if (revealedDiff && controls.revealedDiff !== revealedDiff) {
      setOpen(true)
+    } else if (
+      controls.expandOverride !== expandOverride ||
+      controls.expandSignal !== expandSignal
+    ) {
+      setOpen(expandOverride ?? expandSignal)
    }
-  }, [revealedDiff])
+  }

  const callCount = countToolCalls(blocks) || blocks.length
  const summary = summarizeToolRun(blocks)
@@ -171,7 +179,7 @@ export function NativeChatToolRun({
  // The turn caret opens the activity group, while each child tool remains
  // collapsed. The global expand toolbar still opens child details together.
  const expandToolLines = expandOverride === undefined ? open : false
-  // Other edits remain lazy; journal diffs reuse the rollup's normalized files.
+  // Rollups cache counts only; detailed diff rows are built when the run opens.
  const { editCards, consumedResults } = useMemo(
    () => (open ? buildEditCards(blocks) : NO_EDIT_CARDS),
    [open, blocks]
@@ -4,6 +4,10 @@ import {
  isEditToolName
 } from '../../../../shared/native-chat-edit-normalize'
 import type { NativeChatEditFile } from '../../../../shared/native-chat-edit-model'
+import {
+  editFilesFromPatchText,
+  type NativeChatEditFileSummary
+} from '../../../../shared/native-chat-edit-patch-files'
 import { pairToolBlocks } from './native-chat-tool-fold'

 const normalizedEdits = new WeakMap<
@@ -39,12 +43,12 @@ export const NO_EDIT_CARDS: EditCardModel = { editCards: new Map(), consumedResu
 /** An edit renders as one card, so its result block is folded into the call. The
 *  model decides which calls have landed; a call that has not keeps the generic
 *  tool view, its result still visible as the provider's own error. */
-export function buildEditCards(blocks: NativeChatBlock[], diffOnly = false): EditCardModel {
+export function buildEditCards(blocks: NativeChatBlock[]): EditCardModel {
  const editCards: EditCardModel['editCards'] = new Map()
  const consumedResults: EditCardModel['consumedResults'] = new Set()
  for (const [index, pair] of pairToolBlocks(blocks).entries()) {
    const call = pair.call
-    if (!call || !isEditToolName(call.name) || (diffOnly && call.name !== 'Diff')) {
+    if (!call || !isEditToolName(call.name)) {
      continue
    }
    const files = normalizedEditFiles(call, pair.result, () =>
@@ -73,3 +77,56 @@ export function buildEditCards(blocks: NativeChatBlock[], diffOnly = false): Edi
  }
  return { editCards, consumedResults }
 }
+
+const diffSummaries = new WeakMap<
+  NativeChatBlock,
+  {
+    result: NativeChatBlock | undefined
+    files: NativeChatEditFileSummary[] | null
+  }
+>()
+
+// Only the journal's path-only Diff envelope has counts that can be read without tool normalization.
+export function buildDiffSummaries(blocks: NativeChatBlock[]): Map<
+  NativeChatBlock,
+  {
+    files: NativeChatEditFileSummary[]
+    key: string
+  }
+> {
+  const summaries = new Map<NativeChatBlock, { files: NativeChatEditFileSummary[]; key: string }>()
+  for (const [index, pair] of pairToolBlocks(blocks).entries()) {
+    const { call, result } = pair
+    if (
+      !call ||
+      call.name !== 'Diff' ||
+      call.state === 'running' ||
+      call.state === 'failed' ||
+      result?.isError ||
+      result?.editPatch ||
+      !result?.output
+    ) {
+      continue
+    }
+    const input = call.input
+    if (
+      !input ||
+      typeof input !== 'object' ||
+      !('path' in input) ||
+      typeof input.path !== 'string' ||
+      Object.keys(input).some((key) => key !== 'path')
+    ) {
+      continue
+    }
+    const cached = diffSummaries.get(call)
+    let files = cached?.result === result ? cached.files : undefined
+    if (files === undefined) {
+      files = editFilesFromPatchText(result.output, input.path, true)
+      diffSummaries.set(call, { result, files })
+    }
+    if (files?.length) {
+      summaries.set(call, { files, key: `${call.name}:${index}` })
+    }
+  }
+  return summaries
+}
@@ -1,7 +1,8 @@
+import { MAX_EDIT_LINES } from '../../../../shared/native-chat-edit-model'
 import { describe, expect, it } from 'vitest'
 import type { NativeChatBlock, NativeChatMessage } from '../../../../shared/native-chat-types'
 import { foldToolMessages } from './native-chat-tool-fold'
-import { buildEditCards } from './native-chat-edit-cards'
+import { buildDiffSummaries, buildEditCards } from './native-chat-edit-cards'
 import { nativeChatTurnDiffs } from './native-chat-turn-diffs'

 function diff(id: string, path: string, patch = '@@ -1 +1 @@\n-old\n+new'): NativeChatMessage {
@@ -103,9 +104,20 @@ describe('turn diff rollups', () => {
    ).toBe(0)
  })

-  it('reuses parsed file identity across rollup/card consumers and refreshes new results', () => {
+  it('leaves non-journal Diff envelopes to the deferred tool card', () => {
+    for (const input of [{ path: 'x', patch: '@@\n+override' }, { file_path: 'x' }, null]) {
+      const message = diff('generic', 'x')
+      message.blocks[0] = { type: 'tool-call', name: 'Diff', input }
+      expect(buildDiffSummaries(message.blocks).size).toBe(0)
+    }
+  })
+
+  it('caches counts and deferred card models separately and refreshes new results', () => {
    const message = diff('a', 'a.ts')
-    const first = [...buildEditCards(message.blocks, true).editCards.values()][0]!.files
+    const summary = [...buildDiffSummaries(message.blocks).values()][0]!.files
+    expect([...buildDiffSummaries([...message.blocks]).values()][0]!.files).toBe(summary)
+    expect(summary[0]).not.toHaveProperty('lines')
+    const first = [...buildEditCards(message.blocks).editCards.values()][0]!.files
    expect([...buildEditCards([...message.blocks]).editCards.values()][0]!.files).toBe(first)
    message.blocks = [
      message.blocks[0]!,
@@ -114,5 +126,25 @@ describe('turn diff rollups', () => {
    const updated = [...buildEditCards(message.blocks).editCards.values()][0]!.files
    expect(updated).not.toBe(first)
    expect(updated[0]?.added).toBe(2)
+    const updatedSummary = [...buildDiffSummaries(message.blocks).values()][0]!.files
+    expect(updatedSummary).not.toBe(summary)
+    expect(updatedSummary[0]?.added).toBe(2)
+  })
+
+  it.each([
+    '@@ -1 +1 @@\n-old\n+new',
+    '@@\n--- content\n+++ content\n\\ No newline at end of file',
+    '@@ -1 +1 @@\n-old\n+new\n@@ -5 +5 @@\n-again\n+again',
+    'diff --git a/a.ts b/b.ts\nrename from a.ts\nrename to b.ts',
+    `@@ -0,0 +1,2500 @@\n${'+new\n'.repeat(MAX_EDIT_LINES + 1)}`,
+    `@@ -0,0 +1,2500 @@\n${'+new\n'.repeat(MAX_EDIT_LINES - 1)}@@ -1 +1 @@\n+last`,
+    '@@ -1 +1 @@\n-old\n+new\n… (9999 bytes)'
+  ])('keeps lightweight counts identical to the expanded card (case %#)', (patch) => {
+    const message = diff('parity', 'a.ts', patch)
+    const summary = [...buildDiffSummaries(message.blocks).values()][0]!.files
+    const detailed = [...buildEditCards(message.blocks).editCards.values()][0]!.files
+    expect(summary).toEqual(
+      detailed.map(({ lines: _lines, lineNumbersKnown: _known, ...file }) => file)
+    )
  })
 })
@@ -1,5 +1,5 @@
 import type { NativeChatMessage } from '../../../../shared/native-chat-types'
-import { buildEditCards } from './native-chat-edit-cards'
+import { buildDiffSummaries } from './native-chat-edit-cards'

 export type NativeChatDiffTarget = {
  messageId: string
@@ -35,7 +35,7 @@ export function nativeChatTurnDiffs(
    if (!turnKey) {
      continue
    }
-    for (const edit of buildEditCards(message.blocks, true).editCards.values()) {
+    for (const edit of buildDiffSummaries(message.blocks).values()) {
      let files = turns.get(turnKey)
      if (!files) {
        files = new Map()
@@ -6,13 +6,8 @@ import {
  type NativeChatEditFile,
  type NativeChatEditLine
 } from './native-chat-edit-model'
-import { stripBoundedTextMarker } from './structured-agent-session-projection'
-import {
-  editLinesFromUnifiedPatch,
-  editLinesFromWholeFile,
-  unifiedPatchSections,
-  type UnifiedPatchSection
-} from './native-chat-unified-patch'
+import { editFilesFromPatchText, splitMoveMarker } from './native-chat-edit-patch-files'
+import { editLinesFromUnifiedPatch, editLinesFromWholeFile } from './native-chat-unified-patch'
 import type { NativeChatEditPatch } from './native-chat-types'

 // `NotebookEdit` is deliberately absent: its input carries only the new cell
@@ -25,9 +20,6 @@ const COMMAND_PATCH_TOOLS = new Set(['exec', 'shell', 'local_shell'])
 /** Tools whose input may wrap a `*** Begin Patch` envelope. The dedicated patch
 *  tool applies whatever it is given; a command tool must say that it is. */
 const PATCH_ENVELOPE_TOOLS = new Set(['apply_patch', ...COMMAND_PATCH_TOOLS])
-/** A count standing in for a path, from a producer that joined several files'
- *  patches and kept no per-file path. */
-const FILE_COUNT_PATH = /^\d+ files?$/
 /** Tools whose whole payload is patch text. `Diff` reaches its patch only
 *  through the result, because the structured journal projects a diff item as a
 *  call carrying just the path. */
@@ -172,22 +164,6 @@ function claudeEditFiles(
  ]
 }

-/** A move is appended to the patch body as prose rather than a header field, on
- *  every lane that carries the body as text. Left in place it renders as a
- *  numbered line of the file it moved.
- *
- *  Anchored to the start of the final line: unanchored, a row whose own content
- *  mentions a move was cut in half and the file it names claimed as a rename
- *  that never happened. */
-const MOVE_MARKER = /(?:^|\n)Moved to: (.+)$/
-
-function splitMoveMarker(patch: string): { body: string; movedTo: string | null } {
-  const match = MOVE_MARKER.exec(patch)
-  return match
-    ? { body: patch.slice(0, match.index), movedTo: match[1]!.trim() }
-    : { body: patch, movedTo: null }
-}
-
 function codexChangeFiles(changes: unknown[]): NativeChatEditFile[] {
  return changes.flatMap((entry) => {
    const change = record(entry)
@@ -298,52 +274,5 @@ export function editFilesFromToolPair(pair: {
  if (!patchText) {
    return null
  }
-  // The body carries its own marker when the journal clipped it. Read as
-  // content it becomes a numbered line of the file, and the rows that follow
-  // are reported complete.
-  const bounded = stripBoundedTextMarker(patchText)
-  const moved = splitMoveMarker(bounded.text)
-  // One card per file the patch touches: run together, the later files' rows
-  // and gutter numbers sit under the first file's name.
-  const split = unifiedPatchSections(moved.body)
-  const callerPath = text(input?.path) ?? text(input?.file_path)
-  if (callerPath !== null && FILE_COUNT_PATH.test(callerPath)) {
-    // The producer joined several files' patches and kept a count in place of a
-    // path, so nothing here can name a file. Naming the card after the count
-    // would assert a file that does not exist.
-    return null
-  }
-  // A patch that names one file is the file the call is reporting on, so the
-  // call's own path wins — it is the provider's, where the header's is relative
-  // to the patch. A patch naming several has no one path, and a rename's
-  // destination is only ever in the header. Sections that name nothing are
-  // preamble and must not change that count.
-  const namedSections = split.sections.filter((section) => section.path !== null).length
-  const named = (section: UnifiedPatchSection): string =>
-    (namedSections <= 1 && section.oldPath === null
-      ? (callerPath ?? section.path)
-      : (section.path ?? callerPath)) ?? 'file'
-  const files = split.sections.flatMap((section) => {
-    const parsed = editLinesFromUnifiedPatch(section.body)
-    if (!parsed && section.path === null) {
-      return []
-    }
-    return [
-      finalizeEditFile({
-        path: named(section),
-        oldPath: section.oldPath,
-        changeKind: section.changeKind,
-        lines: parsed?.lines ?? [],
-        lineNumbersKnown: parsed?.lineNumbersKnown ?? false,
-        truncated: bounded.truncated || split.truncated || (parsed?.truncated ?? false)
-      })
-    ]
-  })
-  // The move marker names where the whole patch moved, so it can only speak for
-  // a patch describing one file.
-  if (moved.movedTo !== null && files.length === 1 && files[0]) {
-    const only = files[0]
-    return [{ ...only, path: moved.movedTo, oldPath: only.path, changeKind: 'renamed' }]
-  }
-  return files.length > 0 ? files : null
+  return editFilesFromPatchText(patchText, text(input?.path) ?? text(input?.file_path))
 }
@@ -0,0 +1,106 @@
+import { finalizeEditFile, type NativeChatEditFile } from './native-chat-edit-model'
+import { stripBoundedTextMarker } from './structured-agent-session-projection'
+import {
+  editLinesFromUnifiedPatch,
+  summarizeUnifiedPatch,
+  unifiedPatchSections,
+  type UnifiedPatchSection
+} from './native-chat-unified-patch'
+
+const FILE_COUNT_PATH = /^\d+ files?$/
+
+/** A move is appended to the patch body as prose rather than a header field, on
+ *  every lane that carries the body as text. Left in place it renders as a
+ *  numbered line of the file it moved.
+ *
+ *  Anchored to the start of the final line: unanchored, a row whose own content
+ *  mentions a move was cut in half and the file it names claimed as a rename
+ *  that never happened. */
+const MOVE_MARKER = /(?:^|\n)Moved to: (.+)$/
+
+export function splitMoveMarker(patch: string): { body: string; movedTo: string | null } {
+  const match = MOVE_MARKER.exec(patch)
+  return match
+    ? { body: patch.slice(0, match.index), movedTo: match[1]!.trim() }
+    : { body: patch, movedTo: null }
+}
+
+export type NativeChatEditFileSummary = Pick<
+  NativeChatEditFile,
+  'path' | 'oldPath' | 'changeKind' | 'added' | 'removed' | 'truncated'
+>
+
+export function editFilesFromPatchText(
+  patchText: string,
+  callerPath: string | null
+): NativeChatEditFile[] | null
+export function editFilesFromPatchText(
+  patchText: string,
+  callerPath: string | null,
+  summaryOnly: true
+): NativeChatEditFileSummary[] | null
+export function editFilesFromPatchText(
+  patchText: string,
+  callerPath: string | null,
+  summaryOnly = false
+): NativeChatEditFileSummary[] | null {
+  // The body carries its own marker when the journal clipped it. Read as
+  // content it becomes a numbered line of the file, and the rows that follow
+  // are reported complete.
+  const bounded = stripBoundedTextMarker(patchText)
+  const moved = splitMoveMarker(bounded.text)
+  // One card per file the patch touches: run together, the later files' rows
+  // and gutter numbers sit under the first file's name.
+  const split = unifiedPatchSections(moved.body)
+  if (callerPath !== null && FILE_COUNT_PATH.test(callerPath)) {
+    // The producer joined several files' patches and kept a count in place of a
+    // path, so nothing here can name a file. Naming the card after the count
+    // would assert a file that does not exist.
+    return null
+  }
+  // A patch that names one file is the file the call is reporting on, so the
+  // call's own path wins — it is the provider's, where the header's is relative
+  // to the patch. A patch naming several has no one path, and a rename's
+  // destination is only ever in the header. Sections that name nothing are
+  // preamble and must not change that count.
+  const namedSections = split.sections.filter((section) => section.path !== null).length
+  const named = (section: UnifiedPatchSection): string =>
+    (namedSections <= 1 && section.oldPath === null
+      ? (callerPath ?? section.path)
+      : (section.path ?? callerPath)) ?? 'file'
+  const files = split.sections.flatMap((section) => {
+    const parsed = summaryOnly
+      ? summarizeUnifiedPatch(section.body)
+      : editLinesFromUnifiedPatch(section.body)
+    if (!parsed && section.path === null) {
+      return []
+    }
+    const metadata = {
+      path: named(section),
+      oldPath: section.oldPath,
+      changeKind: section.changeKind,
+      truncated: bounded.truncated || split.truncated || (parsed?.truncated ?? false)
+    }
+    return [
+      summaryOnly
+        ? {
+            ...metadata,
+            added: parsed && 'added' in parsed ? parsed.added : 0,
+            removed: parsed && 'removed' in parsed ? parsed.removed : 0
+          }
+        : finalizeEditFile({
+            ...metadata,
+            lines: parsed && 'lines' in parsed ? parsed.lines : [],
+            lineNumbersKnown:
+              parsed && 'lineNumbersKnown' in parsed ? parsed.lineNumbersKnown : false
+          })
+    ]
+  })
+  // The move marker names where the whole patch moved, so it can only speak for
+  // a patch describing one file.
+  if (moved.movedTo !== null && files.length === 1 && files[0]) {
+    const only = files[0]
+    return [{ ...only, path: moved.movedTo, oldPath: only.path, changeKind: 'renamed' }]
+  }
+  return files.length > 0 ? files : null
+}
@@ -1,5 +1,5 @@
 import { FILE_SECTION_START, isFileHeaderPair } from './native-chat-diff'
-import { pushEditGap, splitEditContent, type NativeChatEditLine } from './native-chat-edit-model'
+import { MAX_EDIT_LINES, splitEditContent, type NativeChatEditLine } from './native-chat-edit-model'

 const HUNK_RANGES = /^@@+ -(\d+)(?:,(\d+))? \+(\d+)(?:,(\d+))? @@/

@@ -22,9 +22,52 @@ export function editLinesFromUnifiedPatch(
  text: string,
  options?: { implicitFirstHunk?: boolean }
 ): UnifiedPatchLines | null {
+  const lines: NativeChatEditLine[] = []
+  const metadata = visitUnifiedPatch(
+    text,
+    (kind, raw, oldLineNumber, newLineNumber) => {
+      lines.push({ kind, text: raw, oldLineNumber, newLineNumber })
+    },
+    options
+  )
+  return metadata ? { lines, ...metadata } : null
+}
+
+/** Counts the same capped rows as a card without allocating its line models. */
+export function summarizeUnifiedPatch(text: string): {
+  added: number
+  removed: number
+  truncated: boolean
+} | null {
+  let added = 0
+  let removed = 0
+  let rowCount = 0
+  const metadata = visitUnifiedPatch(text, (kind) => {
+    rowCount += 1
+    if (rowCount <= MAX_EDIT_LINES) {
+      added += Number(kind === 'add')
+      removed += Number(kind === 'del')
+    }
+  })
+  return metadata
+    ? { added, removed, truncated: metadata.truncated || rowCount > MAX_EDIT_LINES }
+    : null
+}
+
+function visitUnifiedPatch(
+  text: string,
+  visit: (
+    kind: NativeChatEditLine['kind'],
+    text: string,
+    oldLineNumber: number | null,
+    newLineNumber: number | null
+  ) => void,
+  options?: { implicitFirstHunk?: boolean }
+): Omit<UnifiedPatchLines, 'lines'> | null {
  const source = splitEditContent(text)
  const rows = source.lines
-  const lines: NativeChatEditLine[] = []
+  let rowCount = 0
+  let lastWasGap = false
  let oldNo: number | null = null
  let newNo: number | null = null
  let sawHunk = options?.implicitFirstHunk === true
@@ -37,15 +80,15 @@ export function editLinesFromUnifiedPatch(
      const match = HUNK_RANGES.exec(raw)
      oldNo = match ? Number(match[1]) : null
      newNo = match ? Number(match[3]) : null
-      // Successive hunks are separate regions of the file; concatenated with no
-      // break the gutter jumps and the reader sees one continuous block.
-      pushEditGap(lines)
+      if (rowCount > 0 && !lastWasGap) {
+        visit('gap', '', null, null)
+        rowCount += 1
+        lastWasGap = true
+      }
      sawHunk = true
      inHunk = true
      continue
    }
-    // `\ No newline at end of file` sits mid-hunk, between the removed old last
-    // line and the added new one, so it ends nothing.
    if (raw.startsWith('\\')) {
      continue
    }
@@ -60,43 +103,22 @@ export function editLinesFromUnifiedPatch(
    if (!inHunk) {
      continue
    }
-    // Read off the rows rather than the header, so a body that opened with no
-    // header is reported as unlocatable just like a rangeless `@@`.
    ranged &&= oldNo !== null || newNo !== null
+    rowCount += 1
+    lastWasGap = false
    if (raw.startsWith('+')) {
-      lines.push({
-        kind: 'add',
-        text: raw.slice(1),
-        oldLineNumber: null,
-        newLineNumber: newNo
-      })
+      visit('add', raw.slice(1), null, newNo)
      newNo = newNo === null ? null : newNo + 1
-      continue
-    }
-    if (raw.startsWith('-')) {
-      lines.push({
-        kind: 'del',
-        text: raw.slice(1),
-        oldLineNumber: oldNo,
-        newLineNumber: null
-      })
+    } else if (raw.startsWith('-')) {
+      visit('del', raw.slice(1), oldNo, null)
      oldNo = oldNo === null ? null : oldNo + 1
-      continue
+    } else {
+      visit('context', raw.startsWith(' ') ? raw.slice(1) : raw, oldNo, newNo)
+      oldNo = oldNo === null ? null : oldNo + 1
+      newNo = newNo === null ? null : newNo + 1
    }
-    lines.push({
-      kind: 'context',
-      text: raw.startsWith(' ') ? raw.slice(1) : raw,
-      oldLineNumber: oldNo,
-      newLineNumber: newNo
-    })
-    oldNo = oldNo === null ? null : oldNo + 1
-    newNo = newNo === null ? null : newNo + 1
  }
-
-  if (!sawHunk || lines.length === 0) {
-    return null
-  }
-  return { lines, lineNumbersKnown: ranged, truncated: source.truncated }
+  return sawHunk && rowCount > 0 ? { lineNumbersKnown: ranged, truncated: source.truncated } : null
 }

 const GIT_DIFF_HEADER = 'diff --git '
@@ -20,6 +20,64 @@ function item(
 }

 describe('structured agent session status projection', () => {
+  it('reuses immutable item projections and refreshes revisions and resolved prompts', () => {
+    const original = item('diff', 1, {
+      kind: 'diff',
+      path: 'a.ts',
+      patch: {
+        head: '@@\n+first',
+        digest: 'one',
+        byteLength: 10,
+        truncated: false
+      }
+    })
+    const first = projectStructuredItemToNativeChat(original)
+    expect(projectStructuredItemToNativeChat(original)).toBe(first)
+    const revised = {
+      ...original,
+      revision: 2,
+      observedAt: 2000,
+      body: {
+        kind: 'diff' as const,
+        path: 'a.ts',
+        patch: {
+          head: '@@\n+second',
+          digest: 'two',
+          byteLength: 11,
+          truncated: false
+        }
+      }
+    }
+    const second = projectStructuredItemToNativeChat(revised)
+    expect(second).not.toBe(first)
+    expect(second).toMatchObject({
+      timestamp: 2000,
+      blocks: [{ type: 'tool-call' }, { type: 'tool-result', output: '@@\n+second' }]
+    })
+    const pending = item('approval', 2, {
+      kind: 'approval',
+      title: 'Allow?',
+      options: [],
+      resolution: { state: 'pending', selectedOptionId: null, resolvedBy: null, resolvedAt: null }
+    })
+    expect(projectStructuredItemToNativeChat(pending)).toBeNull()
+    if (pending.body.kind !== 'approval') {
+      throw new Error('fixture')
+    }
+    const resolved = {
+      ...pending,
+      revision: 2,
+      body: {
+        ...pending.body,
+        resolution: { ...pending.body.resolution, state: 'resolved' as const }
+      }
+    }
+    expect(projectStructuredItemToNativeChat(resolved)).toMatchObject({
+      id: 'approval',
+      role: 'system'
+    })
+  })
+
  it('projects running, attention, and completed lifecycle states', () => {
    const running = item('running', 1, {
      kind: 'status',
@@ -108,29 +108,37 @@ function itemBlocks(item: AgentJournalRenderItem): {
  }
 }

+const projectedItems = new WeakMap<AgentJournalRenderItem, NativeChatMessage | null>()
+
 export function projectStructuredItemsToNativeChat(
  items: readonly AgentJournalRenderItem[]
 ): NativeChatMessage[] {
  return items.flatMap((item) => {
-    const projected = itemBlocks(item)
-    return projected
-      ? [
-          {
-            id: item.itemId,
-            role: projected.role,
-            blocks: projected.blocks,
-            timestamp: item.observedAt,
-            source: 'transcript'
-          }
-        ]
-      : []
+    const projected = projectStructuredItemToNativeChat(item)
+    return projected ? [projected] : []
  })
 }

 export function projectStructuredItemToNativeChat(
  item: AgentJournalRenderItem
 ): NativeChatMessage | null {
-  return projectStructuredItemsToNativeChat([item])[0] ?? null
+  const cached = projectedItems.get(item)
+  if (cached !== undefined) {
+    return cached
+  }
+  // Reducer updates replace journal items, so unchanged rows keep their render caches.
+  const projected = itemBlocks(item)
+  const message: NativeChatMessage | null = projected
+    ? {
+        id: item.itemId,
+        role: projected.role,
+        blocks: projected.blocks,
+        timestamp: item.observedAt,
+        source: 'transcript'
+      }
+    : null
+  projectedItems.set(item, message)
+  return message
 }

 export function activeStructuredAgentSessionTurnId(