Merge remote-tracking branch 'origin/main' into poteat/diff-parity-2

# Conflicts:
#	mods/diff/hooks/register.ts
#	mods/diff/hooks/views/detail/code-blocks-of/code-blocks-of.ts
#	mods/diff/tests/fixtures/git-in.ts
#	mods/diff/tests/fixtures/in-repository.ts
#	mods/diff/tests/fixtures/index.ts
#	mods/telemetry/tests/fixtures/index.ts

mods/diff/tests/ask/fitted-ask-text-of.test.ts

@@ -0,0 +1,33 @@
+import { describe, expect, test, tier } from 'claude-code/testing'
+
+import Ask from '../../hooks/ask'
+import Fixtures from '../fixtures'
+
+tier('builtin')
+
+describe('fitted-ask-text-of', () => {
+  test('an ask that fits rides whole', () => {
+    expect(
+      Ask.fittedAskTextOf(Fixtures.ASK_TEXT, Fixtures.ASK_TEXT.length),
+    ).toBe(Fixtures.ASK_TEXT)
+  })
+
+  test('an ask past the room keeps its first lines and the cut note', () => {
+    const fitted = Ask.fittedAskTextOf(
+      Fixtures.ASK_TEXT,
+      Fixtures.ROOM_FOR_TWO_LINES,
+    )
+
+    expect(fitted).toBe(
+      `${Fixtures.ASK_LINES.slice(0, 2).join('\n')}\n${Ask.ASK_CUT_NOTE}`,
+    )
+
+    expect(fitted?.length).toBeLessThanOrEqual(Fixtures.ROOM_FOR_TWO_LINES)
+  })
+
+  test('an ask whose first hunk line does not fit is not attached', () => {
+    expect(
+      Ask.fittedAskTextOf(Fixtures.ASK_TEXT, Fixtures.ROOM_FOR_ONE_LINE),
+    ).toBeUndefined()
+  })
+})

mods/diff/tests/backend/backend-of.test.ts

@@ -0,0 +1,66 @@
+import { describe, expect, test, tier } from 'claude-code/testing'
+
+import Backend from '../../hooks/backend'
+import Fixtures from '../fixtures'
+
+tier('builtin')
+
+describe('backend-of', () => {
+  test('as published: no probes, so git or nothing', async () => {
+    const inGit = Fixtures.gitHostOf()
+    const outside = Fixtures.recordingBackendHostOf({})
+
+    expect((await Backend.backendOf(inGit.host, []))?.words.lister).toBe('git')
+    expect(await Backend.backendOf(outside.host, [])).toBeNull()
+
+    expect([inGit.programs, outside.programs]).toEqual([
+      ['git', 'git'],
+      ['git'],
+    ])
+  })
+
+  test('a declining probe leaves a git working tree to git', async () => {
+    const declining = Fixtures.recordingProbeOf(null)
+    const inGit = Fixtures.gitHostOf()
+    const backend = await Backend.backendOf(inGit.host, [declining.probe])
+
+    expect(backend?.words.lister).toBe('git')
+    expect(backend?.baseModes).toEqual(['session', 'uncommitted', 'branch'])
+    expect(declining.asked).toEqual([inGit.host])
+    expect(inGit.programs).toEqual(['git', 'git'])
+  })
+
+  test('a probe that answers pins before git is asked', async () => {
+    const inGit = Fixtures.gitHostOf()
+
+    const backend = await Backend.backendOf(inGit.host, [
+      Fixtures.recordingProbeOf('/home/me/src').probe,
+    ])
+
+    expect(backend?.repository).toEqual({ toplevel: '/home/me/src' })
+    expect(inGit.programs).toEqual([])
+  })
+
+  test('the probes are asked in order and the first answer pins', async () => {
+    const declining = Fixtures.recordingProbeOf(null)
+    const first = Fixtures.recordingProbeOf('/first')
+    const second = Fixtures.recordingProbeOf('/second')
+    const { host } = Fixtures.recordingBackendHostOf({})
+
+    const backend = await Backend.backendOf(host, [
+      declining.probe,
+      first.probe,
+      second.probe,
+    ])
+
+    expect(backend?.repository).toEqual({ toplevel: '/first' })
+
+    expect([
+      declining.asked.length,
+      first.asked.length,
+      second.asked.length,
+    ]).toEqual([1, 1, 0])
+
+    expect(declining.asked[0]).toBe(host)
+  })
+})

mods/diff/tests/classify/is-noise-file.test.ts

@@ -0,0 +1,40 @@
+import { describe, expect, test, tier } from 'claude-code/testing'
+
+import Classify from '../../hooks/classify'
+
+tier('builtin')
+
+describe('is-noise-file', () => {
+  test('tests, fixtures and snapshots are noise', () => {
+    for (const path of [
+      'test/a.ts',
+      'src/x/__tests__/y.ts',
+      'lib/foo.test.tsx',
+      'pkg/bar_test.go',
+      'web/fixtures/data.json',
+      'ui/__snapshots__/a.snap',
+    ]) {
+      expect(Classify.isNoiseFile(path), path).toBe(true)
+    }
+  })
+
+  test('lockfiles, builds, minified and generated files are noise', () => {
+    for (const path of [
+      'bun.lock',
+      'package-lock.json',
+      'dist/index.js',
+      'assets/app.min.js',
+      'types/api.d.ts',
+      'src/constants/prompts.generated/x.ts',
+      'proto/service.pb.go',
+    ]) {
+      expect(Classify.isNoiseFile(path), path).toBe(true)
+    }
+  })
+
+  test('source is not, even with test inside a longer word', () => {
+    for (const path of ['src/contest/entry.ts', 'src/latest.ts', 'README.md']) {
+      expect(Classify.isNoiseFile(path), path).toBe(false)
+    }
+  })
+})

mods/diff/tests/fixtures/answers-of.ts

@@ -11,7 +11,7 @@
  * @param dirty the paths `status` lists as dirty when the session starts
  * @returns the answers by key
  */
-export const repositoryOf = (
+export const answersOf = (
   numstat: string,
   bodies: Readonly<Record<string, string>>,
   dirty: readonly string[] = Object.keys(bodies),

mods/diff/tests/fixtures/ask/ask-lines.ts

@@ -0,0 +1,12 @@
+/**
+ * The lines of an armed ask: where it came from, then one hunk long enough
+ * that two lines and the cut note take less room than the whole.
+ */
+export const ASK_LINES: readonly string[] = [
+  'The user attached the diff of a.txt from the diff pane to this prompt:',
+  '@@ -1,3 +1,3 @@',
+  '-the first old line of a.txt, long enough to take up some room',
+  '-the second old line of a.txt, long enough to take up some room',
+  '+the first new line of a.txt, long enough to take up some room',
+  '+the second new line of a.txt, long enough to take up some room',
+]

mods/diff/tests/fixtures/ask/ask-text.ts

@@ -0,0 +1,6 @@
+import { ASK_LINES } from './ask-lines.js'
+
+/**
+ * ASK_LINES as the one text an armed ask carries.
+ */
+export const ASK_TEXT = ASK_LINES.join('\n')

mods/diff/tests/fixtures/ask/index.ts

@@ -0,0 +1,6 @@
+export * from './ask-lines.js'
+export * from './ask-text.js'
+export * from './room-for-one-line.js'
+export * from './room-for-two-lines.js'
+
+export * as default from '.'

mods/diff/tests/fixtures/ask/room-for-one-line.ts

@@ -0,0 +1,8 @@
+import Ask from '../../../hooks/ask'
+import { ASK_LINES } from './ask-lines.js'
+
+/**
+ * Room for ASK_LINES' heading line and the cut note only, so no hunk line.
+ */
+export const ROOM_FOR_ONE_LINE =
+  (ASK_LINES[0]?.length ?? 0) + 1 + Ask.ASK_CUT_NOTE.length

mods/diff/tests/fixtures/ask/room-for-two-lines.ts

@@ -0,0 +1,11 @@
+import Ask from '../../../hooks/ask'
+import { ASK_LINES } from './ask-lines.js'
+
+/**
+ * Room for ASK_LINES' first two lines and the cut note, each line with its
+ * newline, and not a character more.
+ */
+export const ROOM_FOR_TWO_LINES = ASK_LINES.slice(0, 2).reduce(
+  (sum, line) => sum + line.length + 1,
+  Ask.ASK_CUT_NOTE.length,
+)

mods/diff/tests/fixtures/backend-of/backend-host-of.ts

@@ -0,0 +1,20 @@
+import type Backend from '../../../hooks/backend'
+
+/**
+ * A backend host around one runner: every other member answers nothing (no
+ * file, no mtime, no listing, time zero, a base callback that ignores).
+ *
+ * @param run the host's runner
+ * @returns the host
+ */
+export const backendHostOf = (
+  run: Backend.BackendHost['run'],
+): Backend.BackendHost => ({
+  run,
+  readFile: () => Promise.reject(new Error('ENOENT')),
+  mtimeOf: () => Promise.resolve(null),
+  entryKindsOf: () => Promise.resolve(null),
+  nowMs: () => Promise.resolve(0),
+  sessionStartMsOf: () => 0,
+  onBranchBase: () => undefined,
+})

mods/diff/tests/fixtures/backend-of/git-host-of.ts

@@ -0,0 +1,13 @@
+import Scripted from '../scripted'
+import { GIT_WORKTREE } from './git-worktree.js'
+import { recordingBackendHostOf } from './recording-backend-host-of.js'
+import type { RecordingBackendHost } from './recording-backend-host.js'
+
+/**
+ * A recording backend host inside a git working tree: `rev-parse` answers
+ * the three lines, nothing else is scripted.
+ *
+ * @returns the host and the programs it ran
+ */
+export const gitHostOf = (): RecordingBackendHost =>
+  recordingBackendHostOf({ 'rev-parse': Scripted.ok(GIT_WORKTREE) })

mods/diff/tests/fixtures/backend-of/git-worktree.ts

@@ -0,0 +1,5 @@
+/**
+ * `git rev-parse`'s three lines inside a working tree at /r: the toplevel,
+ * the git dir, the common dir.
+ */
+export const GIT_WORKTREE = '/r\n/r/.git\n/r/.git\n'

mods/diff/tests/fixtures/backend-of/index.ts

@@ -0,0 +1,10 @@
+export * from './backend-host-of.js'
+export * from './git-host-of.js'
+export * from './git-worktree.js'
+export type * from './recording-backend-host.js'
+export * from './recording-backend-host-of.js'
+export type * from './recording-probe.js'
+export * from './recording-probe-of.js'
+export * from './stub-backend-of.js'
+
+export * as default from '.'

mods/diff/tests/fixtures/backend-of/recording-backend-host-of.ts

@@ -0,0 +1,27 @@
+import type { ProcessRunResult } from 'claude-code'
+
+import Scripted from '../scripted'
+import { backendHostOf } from './backend-host-of.js'
+import type { RecordingBackendHost } from './recording-backend-host.js'
+
+/**
+ * A backend host whose runner answers from a script and notes each program
+ * it was asked to run.
+ *
+ * @param script git's answers by subcommand
+ * @returns the host and the programs it ran, in order
+ */
+export function recordingBackendHostOf(
+  script: Readonly<Record<string, ProcessRunResult>>,
+): RecordingBackendHost {
+  const programs: (string | undefined)[] = []
+  const scripted = Scripted.scriptedGitOf(script)
+
+  const host = backendHostOf(([program, ...rest]) => {
+    programs.push(program)
+
+    return scripted.run(rest)
+  })
+
+  return { host, programs }
+}

mods/diff/tests/fixtures/backend-of/recording-backend-host.ts

@@ -0,0 +1,10 @@
+import type Backend from '../../../hooks/backend'
+
+/**
+ * A backend host under test with the programs its runner was asked to run,
+ * in order.
+ */
+export type RecordingBackendHost = {
+  host: Backend.BackendHost
+  programs: readonly (string | undefined)[]
+}

mods/diff/tests/fixtures/backend-of/recording-probe-of.ts

@@ -0,0 +1,24 @@
+import type Backend from '../../../hooks/backend'
+import type { RecordingProbe } from './recording-probe.js'
+import { stubBackendOf } from './stub-backend-of.js'
+
+/**
+ * A backend probe that notes each host it is asked about and answers a stub
+ * backend at the toplevel, or declines (null) when given none.
+ *
+ * @param toplevel the working copy's root, or null to decline
+ * @returns the probe and the hosts it was asked about, in order
+ */
+export function recordingProbeOf(toplevel: string | null): RecordingProbe {
+  const asked: Backend.BackendHost[] = []
+  const answer = toplevel === null ? null : stubBackendOf(toplevel)
+
+  return {
+    asked,
+    probe: host => {
+      asked.push(host)
+
+      return Promise.resolve(answer)
+    },
+  }
+}

mods/diff/tests/fixtures/backend-of/recording-probe.ts

@@ -0,0 +1,9 @@
+import type Backend from '../../../hooks/backend'
+
+/**
+ * A backend probe under test with the hosts it was asked about, in order.
+ */
+export type RecordingProbe = {
+  probe: Backend.BackendProbe
+  asked: readonly Backend.BackendHost[]
+}

mods/diff/tests/fixtures/backend-of/stub-backend-of.ts

@@ -0,0 +1,18 @@
+import type { Backend } from '../../../hooks/backend'
+import Git from '../../../hooks/git'
+
+/**
+ * A backend that holds a working copy at a toplevel and fetches nothing,
+ * its lister word the toplevel so a test can tell which probe pinned.
+ *
+ * @param toplevel the working copy's root
+ * @returns the backend
+ */
+export const stubBackendOf = (toplevel: string): Backend => ({
+  repository: { toplevel },
+  baseModes: ['uncommitted'],
+  words: { ...Git.GIT_WORDS, lister: toplevel },
+  fetchDiff: () => Promise.resolve({ kind: 'unavailable' }),
+  fetchFileHunks: () => Promise.resolve(null),
+  headKeyOf: () => Promise.resolve(''),
+})

mods/diff/tests/fixtures/big-lines.ts

@@ -0,0 +1,4 @@
+/**
+ * A hunk length past what one turn's diff keeps whole.
+ */
+export const BIG_LINES = 1000

mods/diff/tests/fixtures/branch-base-of/feature-head.ts

@@ -0,0 +1,4 @@
+/**
+ * What `rev-parse HEAD` answers on the feature branch.
+ */
+export const FEATURE_HEAD = 'cccccccccccccccccccccccccccccccccccccccc'

mods/diff/tests/fixtures/branch-base-of/index.ts

@@ -0,0 +1,5 @@
+export * from './feature-head.js'
+export * from './local-base.js'
+export * from './origin-base.js'
+
+export * as default from '.'

mods/diff/tests/fixtures/branch-base-of/local-base.ts

@@ -0,0 +1,5 @@
+/**
+ * The merge-base of HEAD and the local default branch, when it differs
+ * from the remote's.
+ */
+export const LOCAL_BASE = 'bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb'

mods/diff/tests/fixtures/branch-base-of/origin-base.ts

@@ -0,0 +1,4 @@
+/**
+ * The merge-base of HEAD and the remote's default branch.
+ */
+export const ORIGIN_BASE = 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa'

mods/diff/tests/fixtures/checkout.ts

@@ -0,0 +1,11 @@
+import type Git from '../../hooks/git'
+
+/**
+ * Where every model and view fixture sits: a plain checkout at `/r` whose
+ * git dir is its common dir.
+ */
+export const CHECKOUT: Git.Repository = {
+  toplevel: '/r',
+  gitDir: '/r/.git',
+  commonDir: '/r/.git',
+}

mods/diff/tests/fixtures/code-blocks-of/are-contiguous.ts

@@ -0,0 +1,19 @@
+import type { ParsedHunk } from './parsed-hunk.js'
+
+/**
+ * Whether each hunk starts where the one before it ended, on both sides:
+ * the sub-hunks of one hunk split leave no line out and repeat none.
+ *
+ * @param parts the hunks in order
+ * @returns true when they abut
+ */
+export const areContiguous = (parts: readonly ParsedHunk[]): boolean =>
+  parts.slice(1).every((part, at) => {
+    const before = parts[at]
+
+    return (
+      before !== undefined &&
+      part.oldStart === before.oldStart + before.oldLines &&
+      part.newStart === before.newStart + before.newLines
+    )
+  })

mods/diff/tests/fixtures/code-blocks-of/hunks-of.ts

@@ -0,0 +1,36 @@
+import type { ParsedHunk } from './parsed-hunk.js'
+
+/**
+ * The hunks a unified-diff `Code` source holds, read as a surface reads
+ * them.
+ *
+ * Each `@@ -a,b +c,d @@` header opens one and the lines under it are its
+ * body; a source that opens with no header holds none.
+ *
+ * @param source the `Code` element's source
+ * @returns the hunks in order
+ */
+export function hunksOf(source: string): ParsedHunk[] {
+  const hunks: ParsedHunk[] = []
+
+  for (const line of source.split('\n')) {
+    const header = /^@@ -(\d+)(?:,(\d+))? \+(\d+)(?:,(\d+))? @@/.exec(line)
+    const last = hunks.at(-1)
+
+    if (header) {
+      hunks.push({
+        oldStart: Number(header[1]),
+        oldLines: Number(header[2] ?? 1),
+        newStart: Number(header[3]),
+        newLines: Number(header[4] ?? 1),
+        lines: [],
+      })
+    } else if (last) {
+      hunks[hunks.length - 1] = { ...last, lines: [...last.lines, line] }
+    } else {
+      return []
+    }
+  }
+
+  return hunks
+}

mods/diff/tests/fixtures/code-blocks-of/index.ts

@@ -0,0 +1,10 @@
+export * from './are-contiguous.js'
+export * from './hunks-of.js'
+export * from './is-within-code-cap.js'
+export * from './mathematical-bold-a.js'
+export type * from './parsed-hunk.js'
+export * from './parsed-hunks-of.js'
+export * from './wide-hunk.js'
+export * from './wide-line-letters.js'
+
+export * as default from '.'

mods/diff/tests/fixtures/code-blocks-of/is-within-code-cap.ts

@@ -0,0 +1,11 @@
+import Views from '../../../hooks/views'
+
+/**
+ * Whether a source is one a `Code` element may carry: at most
+ * MAX_CODE_CHARS, counted in UTF-16 units as the engine counts.
+ *
+ * @param source the block's source
+ * @returns true when the source fits
+ */
+export const isWithinCodeCap = (source: string): boolean =>
+  source.length <= Views.MAX_CODE_CHARS

mods/diff/tests/fixtures/code-blocks-of/mathematical-bold-a.ts

@@ -0,0 +1,7 @@
+/**
+ * U+1D400, a letter beyond the Basic Multilingual Plane: one character on
+ * screen, two UTF-16 units in a string.
+ *
+ * A `Code` source's length is charged in those units.
+ */
+export const MATHEMATICAL_BOLD_A = '\u{1D400}'

mods/diff/tests/fixtures/code-blocks-of/parsed-hunk.ts

@@ -0,0 +1,11 @@
+/**
+ * One hunk read back out of a `Code` source: its header's four numbers and
+ * the marked lines under it.
+ */
+export type ParsedHunk = {
+  oldStart: number
+  oldLines: number
+  newStart: number
+  newLines: number
+  lines: readonly string[]
+}

mods/diff/tests/fixtures/code-blocks-of/parsed-hunks-of.ts

@@ -0,0 +1,12 @@
+import type Views from '../../../hooks/views'
+import { hunksOf } from './hunks-of.js'
+import type { ParsedHunk } from './parsed-hunk.js'
+
+/**
+ * Every hunk a body's `Code` sources hold, in drawing order.
+ *
+ * @param body the file's body as `codeBlocksOf` cut it
+ * @returns the hunks read back out of each source
+ */
+export const parsedHunksOf = (body: Views.CodeBody): ParsedHunk[] =>
+  body.sources.flatMap(hunksOf)

mods/diff/tests/fixtures/code-blocks-of/wide-hunk.ts

@@ -0,0 +1,25 @@
+import type Git from '../../../hooks/git'
+import { WIDE_LINE_LETTERS } from './wide-line-letters.js'
+
+/**
+ * A hunk of wide lines cycling context, removed and added: at its defaults
+ * two share a `Code` and three do not.
+ *
+ * @param start the first line's number on both sides
+ * @param count how many lines
+ * @param letter the character each line repeats WIDE_LINE_LETTERS times
+ * @returns the hunk
+ */
+export function wideHunk(start = 1, count = 40, letter = 'x'): Git.Hunk {
+  const markers = [' ', '-', '+']
+
+  return {
+    oldStart: start,
+    newStart: start,
+    lines: Array.from(
+      { length: count },
+      (_, row) =>
+        `${markers[row % markers.length]}${letter.repeat(WIDE_LINE_LETTERS)}`,
+    ),
+  }
+}

mods/diff/tests/fixtures/code-blocks-of/wide-line-letters.ts

@@ -0,0 +1,4 @@
+/**
+ * How many letters follow each marker in a wide hunk's line.
+ */
+export const WIDE_LINE_LETTERS = 99

mods/diff/tests/fixtures/datings-of/index.ts

@@ -0,0 +1,5 @@
+export * from './root-only-budget.js'
+export * from './tracked-row.js'
+export * from './two-listings-budget.js'
+
+export * as default from '.'

mods/diff/tests/fixtures/datings-of/root-only-budget.ts

@@ -0,0 +1,4 @@
+/**
+ * A kind-walk budget that lists the repository root and nothing under it.
+ */
+export const ROOT_ONLY_BUDGET = 1

mods/diff/tests/fixtures/datings-of/tracked-row.ts

@@ -0,0 +1,14 @@
+import type Git from '../../../hooks/git'
+
+/**
+ * One row under git, a directory deep: past what a root-only walk lists.
+ */
+export const TRACKED_ROW: Git.FileStat = {
+  path: 'deep/x.ts',
+  renamedFrom: null,
+  added: 1,
+  removed: 0,
+  isBinary: false,
+  isUntracked: false,
+  isPreSession: false,
+}

mods/diff/tests/fixtures/datings-of/two-listings-budget.ts

@@ -0,0 +1,4 @@
+/**
+ * A kind-walk budget spent after the root and one directory under it.
+ */
+export const TWO_LISTINGS_BUDGET = 2

mods/diff/tests/fixtures/diff-at.ts

@@ -0,0 +1,15 @@
+import type { CommandRunInput } from 'claude-code'
+
+import { DIFF } from './diff.js'
+
+/**
+ * The command typed under the fullscreen layout on a terminal so many
+ * columns wide, as its presentation tells the hooks.
+ *
+ * @param columns the terminal's width
+ * @returns the command's input
+ */
+export const diffAt = (columns: number): CommandRunInput => ({
+  ...DIFF,
+  presentation: { isFullscreen: true, columns },
+})

mods/diff/tests/fixtures/edit-patch-of.ts

@@ -0,0 +1,12 @@
+/**
+ * An Edit tool's result record holding one hunk of one file.
+ *
+ * @param lines the hunk's lines, `-`/`+`/space prefixed
+ * @returns the record as the transcript stores it
+ */
+export const editPatchOf = (lines: string[]) => ({
+  filePath: '/r/a.ts',
+  structuredPatch: [
+    { oldStart: 1, oldLines: 1, newStart: 1, newLines: 1, lines },
+  ],
+})

mods/diff/tests/fixtures/fetch-diff/before-session-ms.ts

@@ -0,0 +1,5 @@
+/**
+ * An mtime that predates GIT_SESSION_START_MS: a file last touched before
+ * the session.
+ */
+export const BEFORE_SESSION_MS = 500

mods/diff/tests/fixtures/fetch-diff/deep-directories.ts

@@ -0,0 +1,5 @@
+/**
+ * How many top-level directories, each with a nested one, the wide layout
+ * case lists and dates.
+ */
+export const DEEP_DIRECTORIES = 100

mods/diff/tests/fixtures/fetch-diff/during-session-ms.ts

@@ -0,0 +1,4 @@
+/**
+ * An mtime past GIT_SESSION_START_MS: a file touched this session.
+ */
+export const DURING_SESSION_MS = 2_000

mods/diff/tests/fixtures/fetch-diff/fetch-repository.ts

@@ -0,0 +1,10 @@
+import type Git from '../../../hooks/git'
+
+/**
+ * The repository the fetch cases run in: a plain checkout at `/repo`.
+ */
+export const FETCH_REPOSITORY: Git.Repository = {
+  toplevel: '/repo',
+  gitDir: '/repo/.git',
+  commonDir: '/repo/.git',
+}

mods/diff/tests/fixtures/fetch-diff/files-listing.ts

@@ -0,0 +1,18 @@
+import type Git from '../../../hooks/git'
+
+/**
+ * What the working tree lists as: the files the cases name are plain
+ * files; the link, the leak and the submodule are something else.
+ */
+export const FILES_LISTING: readonly (readonly [string, Git.EntryKind])[] = [
+  ['old.ts', 'file'],
+  ['new.ts', 'file'],
+  ['scratch.txt', 'file'],
+  ['stale.txt', 'file'],
+  ['fresh.txt', 'file'],
+  ['a.ts', 'file'],
+  ['staged.ts', 'file'],
+  ['link.ts', 'other'],
+  ['leak', 'other'],
+  ['sub', 'other'],
+]

mods/diff/tests/fixtures/fetch-diff/git-session-start-ms.ts

@@ -0,0 +1,5 @@
+/**
+ * When the session began, for the git cases that date files against it by
+ * hand-picked mtimes.
+ */
+export const GIT_SESSION_START_MS = 1_000

mods/diff/tests/fixtures/fetch-diff/index.ts

@@ -0,0 +1,12 @@
+export * from './before-session-ms.js'
+export * from './deep-directories.js'
+export * from './during-session-ms.js'
+export * from './fetch-repository.js'
+export * from './files-listing.js'
+export * from './git-session-start-ms.js'
+export * from './merge-head-linked.js'
+export * from './merging.js'
+export * from './one-staged.js'
+export * from './vs-head.js'
+
+export * as default from '.'

mods/diff/tests/fixtures/fetch-diff/merge-head-linked.ts

@@ -0,0 +1,8 @@
+import type Git from '../../../hooks/git'
+
+/**
+ * A git dir listing whose MERGE_HEAD is a symbolic link, so no merge is in
+ * progress as far as the fetch is concerned.
+ */
+export const MERGE_HEAD_LINKED: readonly (readonly [string, Git.EntryKind])[] =
+  [['MERGE_HEAD', 'other']]

mods/diff/tests/fixtures/fetch-diff/merging.ts

@@ -0,0 +1,8 @@
+import type Git from '../../../hooks/git'
+
+/**
+ * A git dir listing mid-merge: MERGE_HEAD is a plain file.
+ */
+export const MERGING: readonly (readonly [string, Git.EntryKind])[] = [
+  ['MERGE_HEAD', 'file'],
+]

mods/diff/tests/fixtures/fetch-diff/one-staged.ts

@@ -0,0 +1,4 @@
+/**
+ * A shortstat line for one staged file of three insertions.
+ */
+export const ONE_STAGED = ' 1 file changed, 3 insertions(+)'

mods/diff/tests/fixtures/fetch-diff/vs-head.ts

@@ -0,0 +1,5 @@
+/**
+ * The argv fragment of the diff against HEAD, to script it as failing.
+ */
+export const VS_HEAD =
+  'diff.relative=false diff --ignore-submodules=dirty --submodule=short HEAD'

mods/diff/tests/fixtures/git-in.ts

@@ -1,21 +1,25 @@
 import type { ProcessRunResult } from 'claude-code'
 
 import { NOT_A_REPOSITORY } from './not-a-repository.js'
+import { REPOSITORY } from './repository.js'
 
 /**
- * What git answers in /work; an invocation the answers do not know fails
- * as git does outside a repository.
+ * What git answers from a script of outputs by command-line key, REPOSITORY
+ * when none is given.
+ *
+ * An invocation the script does not know fails as git does outside a
+ * repository.
  *
  * @param argv the invocation, program first
- * @param answers git's output by a key the invocation's command line holds
+ * @param script git's output for each invocation whose line holds the key
  * @returns git's exit code and output
  */
 export function gitIn(
   argv: readonly string[],
-  answers: Readonly<Record<string, string>>,
+  script: Readonly<Record<string, string>> = REPOSITORY,
 ): ProcessRunResult {
   const line = argv.join(' ')
-  const found = Object.entries(answers).find(([key]) => line.includes(key))
+  const found = Object.entries(script).find(([key]) => line.includes(key))
 
   return found
     ? { exitCode: 0, stdout: found[1], stderr: '' }

mods/diff/tests/fixtures/head-key-of/head-sha.ts

@@ -0,0 +1,4 @@
+/**
+ * What the scripted `rev-parse` answers when the key falls back to git.
+ */
+export const HEAD_SHA = '0123456789abcdef0123456789abcdef01234567'

mods/diff/tests/fixtures/head-key-of/index.ts

@@ -0,0 +1,4 @@
+export * from './head-sha.js'
+export * from './stamp.js'
+
+export * as default from '.'

mods/diff/tests/fixtures/head-key-of/stamp.ts

@@ -0,0 +1,4 @@
+/**
+ * The mtime every stat in the HEAD-key cases answers.
+ */
+export const STAMP = 42

mods/diff/tests/fixtures/header-totals-of/index.ts

@@ -0,0 +1,8 @@
+export * from './past-cap-count.js'
+export * from './pre-session-row.js'
+export * from './reported-count.js'
+export * from './session-row.js'
+export * from './stored-count.js'
+export * from './test-row.js'
+
+export * as default from '.'

mods/diff/tests/fixtures/header-totals-of/past-cap-count.ts

@@ -0,0 +1,5 @@
+/**
+ * A reported file count past the row cap: ten files git counted but the
+ * model never stored.
+ */
+export const PAST_CAP_COUNT = 60

mods/diff/tests/fixtures/header-totals-of/pre-session-row.ts

@@ -0,0 +1,14 @@
+import type Git from '../../../hooks/git'
+
+/**
+ * A file last changed before the session: its lines leave the header.
+ */
+export const PRE_SESSION_ROW: Git.FileStat = {
+  path: 'old.ts',
+  renamedFrom: null,
+  added: 5,
+  removed: 1,
+  isBinary: false,
+  isUntracked: false,
+  isPreSession: true,
+}

mods/diff/tests/fixtures/header-totals-of/reported-count.ts

@@ -0,0 +1,4 @@
+/**
+ * The file count git reported, two more than the rows stored.
+ */
+export const REPORTED_COUNT = 4

mods/diff/tests/fixtures/header-totals-of/session-row.ts

@@ -0,0 +1,14 @@
+import type Git from '../../../hooks/git'
+
+/**
+ * A source file changed this session: three added, one removed.
+ */
+export const SESSION_ROW: Git.FileStat = {
+  path: 'src/a.ts',
+  renamedFrom: null,
+  added: 3,
+  removed: 1,
+  isBinary: false,
+  isUntracked: false,
+  isPreSession: false,
+}

mods/diff/tests/fixtures/header-totals-of/stored-count.ts

@@ -0,0 +1,4 @@
+/**
+ * How many rows the model stored in the past-the-cap case.
+ */
+export const STORED_COUNT = 50

mods/diff/tests/fixtures/header-totals-of/test-row.ts

@@ -0,0 +1,14 @@
+import type Git from '../../../hooks/git'
+
+/**
+ * A test file changed this session, which the partition counts as noise.
+ */
+export const TEST_ROW: Git.FileStat = {
+  path: 'test/a.test.ts',
+  renamedFrom: null,
+  added: 3,
+  removed: 1,
+  isBinary: false,
+  isUntracked: false,
+  isPreSession: false,
+}

mods/diff/tests/fixtures/hint-at.ts

@@ -0,0 +1,15 @@
+import type { RenderInput } from 'claude-code'
+
+import { HINT } from './hint.js'
+
+/**
+ * The prompt's hint on a terminal so many columns wide: drawing it is how
+ * the plugin learns the width.
+ *
+ * @param columns the terminal's width
+ * @returns the `ui.render` input
+ */
+export const hintAt = (columns: number): RenderInput<'PromptHint'> => ({
+  ...HINT,
+  viewport: { columns, rows: HINT.viewport?.rows ?? columns },
+})

mods/diff/tests/fixtures/in-repository.ts

@@ -8,21 +8,27 @@ import { REPOSITORY } from './repository.js'
 import { startsSession } from './starts-session.js'
 
 /**
- * A session in /work (REPOSITORY), keeping each git run and each pane
- * opened or closed.
+ * A session in a repository git answers for from a script (REPOSITORY, in
+ * /work, when none is given), keeping what the plugin does there.
  *
- * The store starts empty, the clock at 0, and the engine draws the hint.
+ * Kept: each git run, ring move, pane opened or closed, status line. The clock
+ * starts at 0 and the engine draws the hint. A test that rewrites the
+ * script between calls changes what git answers next.
  *
  * @param on the test's `on`
- * @param answers git's output by invocation key; one changed file when absent
- * @returns the runs, the panes opened and closed, and the session's clock
+ * @param script git's output for each invocation whose line holds the key
+ * @param stored what the plugin's store holds at the start
+ * @returns the runs, the ring's moves, the panes opened and closed, the
+ *   statuses, the clock
  */
 export function inRepository(
   on: On,
-  answers: Readonly<Record<string, string>> = REPOSITORY,
+  script: Readonly<Record<string, string>> = REPOSITORY,
+  stored: Readonly<Record<string, unknown>> = {},
 ) {
   const runs: Args<'process.run'>[] = []
   const focused: Args<'ui.focus'>[] = []
+  const statuses: (string | undefined)[] = []
   const opened = keeping<Args<'ui.open'>>()
   const closed = keeping<Args<'ui.close'>>()
   const clock = startsSession(on)
@@ -30,7 +36,7 @@ export function inRepository(
   on('process.run', ($, e) => {
     runs.push(e)
 
-    return { value: gitIn(e.argv, answers) }
+    return { value: gitIn(e.argv, script) }
   })
 
   on('ui.focus', (_engine, e) => {
@@ -39,12 +45,25 @@ export function inRepository(
     return {}
   })
 
+  on('ui.status', ($, e) => {
+    statuses.push(e.text)
+
+    return { value: undefined }
+  })
+
   on('ui.open', opened.hook)
   on('ui.close', closed.hook)
   on('ui.invalidate', () => ({ value: undefined }))
   on('ui.render', { component: 'PromptHint' }, () => HINT_DRAWN)
   on('session.messages', () => ({ value: [] }))
-  mock.store(on)
+  mock.store(on, stored)
 
-  return { runs, focused, opened: opened.kept, closed: closed.kept, clock }
+  return {
+    runs,
+    focused,
+    opened: opened.kept,
+    closed: closed.kept,
+    statuses,
+    clock,
+  }
 }

mods/diff/tests/fixtures/index.ts

@@ -1,31 +1,58 @@
+export * from './answers-of.js'
+export * from './ask'
+export * from './backend-of'
+export * from './big-lines.js'
+export * from './branch-base-of'
 export * from './builtin-holds.js'
+export * from './checkout.js'
 export * from './clear.js'
+export * from './code-blocks-of'
+export * from './datings-of'
 export * from './dialog-diff.js'
 export * from './diff.js'
+export * from './diff-at.js'
+export * from './edit-patch-of.js'
+export * from './fetch-diff'
 export * from './git-hung.js'
 export * from './git-in.js'
+export * from './head-key-of'
+export * from './header-totals-of'
 export * from './hint.js'
+export * from './hint-at.js'
 export * from './hint-drawn.js'
 export * from './in-repository.js'
 export * from './inline-pane.js'
 export * from './keeping.js'
+export * from './kind-walk-of'
 export * from './many-file-count.js'
 export * from './many-files.js'
+export * from './mode-label-of'
 export * from './moved-in.js'
 export * from './narrow-inline-pane.js'
+export * from './no-stats.js'
 export * from './not-a-repository.js'
 export * from './old-files.js'
 export * from './pane.js'
+export * from './pane-view'
+export * from './parse-file-diff'
 export * from './renamed.js'
 export * from './repository.js'
-export * from './repository-of.js'
+export * from './repository-of'
 export * from './ring-onto.js'
+export * from './scripted'
 export * from './session.js'
 export * from './settle-ms.js'
 export * from './starts-session.js'
-export * from './text-of.js'
+export * from './todo-write-of.js'
+export * from './tree'
+export * from './truncate-start'
+export * from './turn-diffs-of'
 export * from './two-files.js'
+export * from './typed-prompt-of.js'
+export * from './vs-main.js'
 export * from './wheel-over-list.js'
 export * from './wheel-tick.js'
+export * from './worktree'
+export * from './wrapped-lines'
 
 export * as default from '.'

mods/diff/tests/fixtures/kind-walk-of/index.ts

@@ -0,0 +1,4 @@
+export * from './walk-budget.js'
+export * from './walk-depth.js'
+
+export * as default from '.'

mods/diff/tests/fixtures/kind-walk-of/walk-budget.ts

@@ -0,0 +1,4 @@
+/**
+ * How many directory listings the kind walk may spend.
+ */
+export const WALK_BUDGET = 8

mods/diff/tests/fixtures/kind-walk-of/walk-depth.ts

@@ -0,0 +1,4 @@
+/**
+ * The depth of the path that outruns any listing budget.
+ */
+export const WALK_DEPTH = 50_000

mods/diff/tests/fixtures/many-files.ts

@@ -1,11 +1,11 @@
+import { answersOf } from './answers-of.js'
 import { MANY_FILE_COUNT } from './many-file-count.js'
-import { repositoryOf } from './repository-of.js'
 
 /**
  * Git's output in /work where MANY_FILE_COUNT files changed a line each:
  * more rows than the docked list shows at once.
  */
-export const MANY_FILES = repositoryOf(
+export const MANY_FILES = answersOf(
   Array.from(
     { length: MANY_FILE_COUNT },
     (_, at) => `1\t1\tfile${at}.ts\0`,

mods/diff/tests/fixtures/mode-label-of/at-sha.ts

@@ -0,0 +1,9 @@
+import type Git from '../../../hooks/git'
+
+/**
+ * A working-tree source whose backend names its own base, a short sha.
+ */
+export const AT_SHA: Git.DiffSource = {
+  kind: 'working-tree',
+  base: '8634408015c1',
+}

mods/diff/tests/fixtures/mode-label-of/index.ts

@@ -0,0 +1,5 @@
+export * from './at-sha.js'
+export * from './one-file.js'
+export * from './working-tree.js'
+
+export * as default from '.'

mods/diff/tests/fixtures/mode-label-of/one-file.ts

@@ -0,0 +1,10 @@
+import type Git from '../../../hooks/git'
+
+/**
+ * The totals of a diff with one file of one added line.
+ */
+export const ONE_FILE: Git.DiffStats = {
+  filesCount: 1,
+  linesAdded: 1,
+  linesRemoved: 0,
+}

mods/diff/tests/fixtures/mode-label-of/working-tree.ts

@@ -0,0 +1,9 @@
+import type Git from '../../../hooks/git'
+
+/**
+ * A diff source that compares against the working tree, its base HEAD.
+ */
+export const WORKING_TREE: Git.DiffSource = {
+  kind: 'working-tree',
+  base: 'HEAD',
+}

mods/diff/tests/fixtures/moved-in.ts

@@ -1,10 +1,10 @@
-import { repositoryOf } from './repository-of.js'
+import { answersOf } from './answers-of.js'
 
 /**
  * Git's output in /work where two old files differ from HEAD: one dirty
  * before the session began, one moved into place since (not dirty then).
  */
-export const MOVED_IN = repositoryOf(
+export const MOVED_IN = answersOf(
   '1\t1\told.ts\0' + '1\t1\tmoved.ts\0',
   {
     'old.ts': '@@ -1 +1 @@\n-a\n+b\n',

mods/diff/tests/fixtures/no-stats.ts

@@ -0,0 +1,10 @@
+import type Git from '../../hooks/git'
+
+/**
+ * The totals of a diff with nothing in it.
+ */
+export const NO_STATS: Git.DiffStats = {
+  filesCount: 0,
+  linesAdded: 0,
+  linesRemoved: 0,
+}

mods/diff/tests/fixtures/pane-view/big-body-of.ts

@@ -0,0 +1,24 @@
+import type Git from '../../../hooks/git'
+import Limits from '../../../hooks/limits'
+import { LONG_LINE_CHARS } from './long-line-chars.js'
+
+/**
+ * A body of one hunk at the line cap whose every line is long: more text
+ * than the pane's whole body budget holds.
+ *
+ * @returns the body
+ */
+export const bigBodyOf = (): Git.FileHunks => ({
+  hunks: [
+    {
+      oldStart: 0,
+      newStart: 1,
+      lines: Array.from(
+        { length: Limits.MAX_LINES_PER_FILE },
+        (_, at) => `+const value${at} = ${'0'.repeat(LONG_LINE_CHARS)}`,
+      ),
+    },
+  ],
+  isTruncated: false,
+  isLarge: false,
+})

mods/diff/tests/fixtures/pane-view/bodies-of.ts

@@ -0,0 +1,14 @@
+import type Git from '../../../hooks/git'
+import type PaneState from '../../../hooks/pane-state'
+
+/**
+ * The pane's read bodies holding one body under each of the given paths.
+ *
+ * @param body the body every path reads
+ * @param paths the files that have it
+ * @returns the bodies by path
+ */
+export const bodiesOf = (
+  body: Git.FileHunks,
+  ...paths: readonly string[]
+): PaneState.Bodies => new Map(paths.map(path => [path, body]))

mods/diff/tests/fixtures/pane-view/body-rows.ts

@@ -0,0 +1,4 @@
+/**
+ * The pane's body rows in the ordinary cases: docked in a 40-row terminal.
+ */
+export const BODY_ROWS = 35

mods/diff/tests/fixtures/pane-view/builtin-headline-row.ts

@@ -0,0 +1,8 @@
+/**
+ * The panel row the built-in draws its empty headline on, docked in a
+ * 40-row terminal over one pre-session file.
+ *
+ * Its header's top pad, the close, the header's bottom pad, then half the
+ * spare rows.
+ */
+export const BUILTIN_HEADLINE_ROW = 17

mods/diff/tests/fixtures/pane-view/columns.ts

@@ -0,0 +1,4 @@
+/**
+ * The pane's body width in the ordinary cases.
+ */
+export const COLUMNS = 60

mods/diff/tests/fixtures/pane-view/config-detail-of.ts

@@ -0,0 +1,19 @@
+import type Views from '../../../hooks/views'
+import { SMALL_BODY } from './small-body.js'
+
+/**
+ * A config file as the detail view takes it: untracked with no body read,
+ * or tracked with a small body ready.
+ *
+ * @param isUntracked whether the file is untracked
+ * @returns the detail model
+ */
+export const configDetailOf = (isUntracked: boolean): Views.DetailModel => ({
+  words: { untrackedNoteOf: () => ['New file not yet staged.'] },
+  path: 'src/app/config.ts',
+  displayPath: 'src/app/config.ts',
+  isUntracked,
+  isBinary: false,
+  body: isUntracked ? undefined : SMALL_BODY,
+  isArmed: false,
+})

mods/diff/tests/fixtures/pane-view/cramped-rows.ts

@@ -0,0 +1,4 @@
+/**
+ * Body rows too few to center an empty state in, so it stacks from the top.
+ */
+export const CRAMPED_ROWS = 4

mods/diff/tests/fixtures/pane-view/dock-seat.ts

@@ -0,0 +1,10 @@
+import type Views from '../../../hooks/views'
+import { VIEW_PANE } from './view-pane.js'
+
+/**
+ * VIEW_PANE's seat: docked beside the transcript on its 160-column terminal.
+ */
+export const DOCK_SEAT: Views.PaneSeat = {
+  placement: 'dock',
+  terminalColumns: VIEW_PANE.viewport?.columns ?? null,
+}

mods/diff/tests/fixtures/pane-view/docked-pane.ts

@@ -0,0 +1,20 @@
+import type { On, RenderElement } from 'claude-code'
+import type { Engine } from 'claude-code/testing'
+
+import type PaneState from '../../../hooks/pane-state'
+import { docksPane } from './docks-pane.js'
+
+/**
+ * The pane docked beneath the plugin over one model, drawn once through the
+ * engine: the tree the engine took.
+ *
+ * @param $ the test's `$`
+ * @param on the test's `on`
+ * @param model the pane's model
+ * @returns the tree
+ */
+export const dockedPane = (
+  $: Engine,
+  on: On,
+  model: PaneState.PaneModel,
+): Promise<RenderElement> => docksPane($, on)(model)

mods/diff/tests/fixtures/pane-view/docks-pane.ts

@@ -0,0 +1,43 @@
+import type { On, RenderElement } from 'claude-code'
+import type { Engine } from 'claude-code/testing'
+
+import PaneState from '../../../hooks/pane-state'
+import Views from '../../../hooks/views'
+import { drawsPane } from './draws-pane.js'
+import { VIEW_PANE } from './view-pane.js'
+
+/**
+ * The pane seated beneath the plugin over whichever model the test hands
+ * next: docked on a 160-column terminal unless the overrides say inline.
+ *
+ * Each call draws VIEW_PANE through the engine with `paneView` over that
+ * model and answers the tree the engine took.
+ *
+ * @param $ the test's `$`
+ * @param on the test's `on`
+ * @param overrides kit members and the seat that differ from the ordinary
+ * @returns draws the pane over a model
+ */
+export function docksPane(
+  $: Engine,
+  on: On,
+  overrides: Partial<Omit<Views.Kit, 'ui'> & Views.PaneSeat> = {},
+): (model: PaneState.PaneModel) => Promise<RenderElement> {
+  const {
+    placement = 'dock',
+    terminalColumns = VIEW_PANE.viewport?.columns ?? null,
+    ...kit
+  } = overrides
+
+  const seat: Views.PaneSeat = { placement, terminalColumns }
+
+  let model = PaneState.INITIAL_MODEL
+
+  drawsPane(on, drawn => Views.paneView(drawn, model, seat), kit)
+
+  return next => {
+    model = next
+
+    return $.ui.render(VIEW_PANE)
+  }
+}

mods/diff/tests/fixtures/pane-view/draws-pane.ts

@@ -0,0 +1,39 @@
+import type { On, RenderElement } from 'claude-code'
+
+import { isOnPaneSurface } from '../../../hooks/is-on-pane-surface'
+import type Views from '../../../hooks/views'
+import { BODY_ROWS } from './body-rows.js'
+import { COLUMNS } from './columns.js'
+import { noopActionsOf } from './noop-actions-of.js'
+
+/**
+ * Draws a pane beneath the plugin with a view of the test's, handed the kit
+ * every view takes.
+ *
+ * The hook resolves the surface's elements; the body size is the view
+ * fixtures' and the actions do nothing, unless overridden.
+ *
+ * @param on the test's `on`
+ * @param view draws the tree from the kit
+ * @param overrides kit members that differ from the ordinary ones
+ */
+export const drawsPane = (
+  on: On,
+  view: (kit: Views.Kit) => RenderElement,
+  overrides: Partial<Omit<Views.Kit, 'ui'>> = {},
+) =>
+  on('ui.render', { component: 'Pane' }, async ($, e, next) => {
+    if (!isOnPaneSurface(e)) {
+      return next(e)
+    }
+
+    const { Box, Text, Button, Select, Code } = await $.ui.resolve(e)
+
+    return view({
+      ui: { Box, Text, Button, Select, Code },
+      actions: noopActionsOf(),
+      columns: COLUMNS,
+      rows: BODY_ROWS,
+      ...overrides,
+    })
+  })

mods/diff/tests/fixtures/pane-view/index.ts

@@ -0,0 +1,28 @@
+export * from './big-body-of.js'
+export * from './bodies-of.js'
+export * from './body-rows.js'
+export * from './builtin-headline-row.js'
+export * from './columns.js'
+export * from './config-detail-of.js'
+export * from './cramped-rows.js'
+export * from './dock-seat.js'
+export * from './docked-pane.js'
+export * from './docks-pane.js'
+export * from './draws-pane.js'
+export * from './long-line-chars.js'
+export * from './long-path-segments.js'
+export * from './narrow-seat.js'
+export * from './noop.js'
+export * from './noop-actions-of.js'
+export * from './row-of.js'
+export * from './row-shape-of.js'
+export * from './row-shapes-of.js'
+export * from './small-body.js'
+export * from './totals.js'
+export * from './tracked.js'
+export * from './turn-two.js'
+export * from './view-pane.js'
+export * from './vs-spoofed.js'
+export * from './whole-place.js'
+
+export * as default from '.'

mods/diff/tests/fixtures/pane-view/long-line-chars.ts

@@ -0,0 +1,5 @@
+/**
+ * How long each line of the budget case runs: four hundred of them outgrow
+ * the body's character budget.
+ */
+export const LONG_LINE_CHARS = 300

mods/diff/tests/fixtures/pane-view/long-path-segments.ts

@@ -0,0 +1,5 @@
+/**
+ * How many directory segments make a selected path longer than the engine
+ * allows one string to be.
+ */
+export const LONG_PATH_SEGMENTS = 2_500

mods/diff/tests/fixtures/pane-view/narrow-seat.ts

@@ -0,0 +1,11 @@
+import Limits from '../../../hooks/limits'
+import type Views from '../../../hooks/views'
+
+/**
+ * A pane seated inline on a terminal one column short of the built-in
+ * panel's width.
+ */
+export const NARROW_SEAT: Views.PaneSeat = {
+  placement: 'inline',
+  terminalColumns: Limits.OPEN_MIN_COLUMNS - 1,
+}

mods/diff/tests/fixtures/pane-view/noop-actions-of.ts

@@ -0,0 +1,17 @@
+import type Views from '../../../hooks/views'
+import { noop } from './noop.js'
+
+/**
+ * Pane actions that each do nothing, for a tree drawn only to be read.
+ *
+ * @returns the actions
+ */
+export const noopActionsOf = (): Views.PaneActions => ({
+  selectFile: noop,
+  toggleNoise: noop,
+  togglePreSession: noop,
+  scrollList: noop,
+  cycleBase: noop,
+  chooseSource: noop,
+  toggleAsk: noop,
+})

mods/diff/tests/fixtures/pane-view/noop.ts

@@ -0,0 +1,7 @@
+/**
+ * An action that does nothing, for a view whose actions a case never
+ * presses.
+ *
+ * @returns undefined
+ */
+export const noop = () => undefined

mods/diff/tests/fixtures/pane-view/row-of.ts

@@ -0,0 +1,22 @@
+import type Git from '../../../hooks/git'
+import { TRACKED } from './tracked.js'
+
+/**
+ * A file row at a path: two added, one removed, tracked and in session,
+ * unless the overrides say otherwise.
+ *
+ * @param path the row's path
+ * @param overrides fields that differ from the ordinary row
+ * @returns the row
+ */
+export const rowOf = (
+  path: string,
+  overrides: Partial<Git.FileStat> = {},
+): Git.FileStat => ({
+  path,
+  renamedFrom: null,
+  added: 2,
+  removed: 1,
+  ...TRACKED,
+  ...overrides,
+})

mods/diff/tests/fixtures/pane-view/row-shape-of.ts

@@ -0,0 +1,18 @@
+import Tree from '../tree'
+
+/**
+ * A pane row as the layout tests read it: `blank` for a bare one-row Box,
+ * `rule` for a line of rule characters, else its first label or its strings.
+ *
+ * @param node a row of the pane's body
+ * @returns the row's shape
+ */
+export function rowShapeOf(node: unknown) {
+  const text = Tree.jsonOf(node)
+  const strings = Tree.stringsOf(node).join('')
+  const label = /"label":"([^"]*)"/.exec(text)?.[1]
+  const isBlank = text === '{"type":"Box","props":{"height":1}}'
+  const isRule = /^─+$/.test(strings)
+
+  return isBlank ? 'blank' : isRule ? 'rule' : (label ?? strings)
+}

mods/diff/tests/fixtures/pane-view/row-shapes-of.ts

@@ -0,0 +1,12 @@
+import Tree from '../tree'
+import { rowShapeOf } from './row-shape-of.js'
+
+/**
+ * The rows of a pane's body, top to bottom, each as the layout tests read
+ * it (rowShapeOf).
+ *
+ * @param tree the pane's tree, its body the first child
+ * @returns each row's shape
+ */
+export const rowShapesOf = (tree: unknown) =>
+  Tree.childrenOf(Tree.childrenOf(tree)[0]).map(rowShapeOf)

mods/diff/tests/fixtures/pane-view/small-body.ts

@@ -0,0 +1,11 @@
+import type Git from '../../../hooks/git'
+
+/**
+ * A one-hunk body with a context line, a removal and an addition: enough
+ * to draw the word highlight.
+ */
+export const SMALL_BODY: Git.FileHunks = {
+  hunks: [{ oldStart: 1, newStart: 1, lines: [' ctx', '-old', '+new'] }],
+  isTruncated: false,
+  isLarge: false,
+}

mods/diff/tests/fixtures/pane-view/totals.ts

@@ -0,0 +1,11 @@
+import type Git from '../../../hooks/git'
+
+/**
+ * What every pane-view diff sums to; the file count is replaced by the
+ * number of rows a case gives.
+ */
+export const TOTALS: Git.DiffStats = {
+  filesCount: 1,
+  linesAdded: 9,
+  linesRemoved: 3,
+}

mods/diff/tests/fixtures/pane-view/tracked.ts

@@ -0,0 +1,8 @@
+/**
+ * The flags of an ordinary row: text, tracked, changed this session.
+ */
+export const TRACKED = {
+  isBinary: false,
+  isUntracked: false,
+  isPreSession: false,
+} as const

mods/diff/tests/fixtures/pane-view/turn-two.ts

@@ -0,0 +1,20 @@
+import type Turns from '../../../hooks/turns'
+
+/**
+ * The second turn of a session as the turns model keeps it: one created
+ * file, its hunk cut at the line cap.
+ */
+export const TURN_TWO: Turns.TurnDiff = {
+  index: 2,
+  preview: 'fix it',
+  files: [
+    {
+      path: '/r/a.ts',
+      hunks: [{ oldStart: 1, newStart: 1, lines: ['+x'] }],
+      added: 1,
+      removed: 0,
+      isNewFile: true,
+      isTruncated: true,
+    },
+  ],
+}

mods/diff/tests/fixtures/pane-view/view-pane.ts

@@ -0,0 +1,25 @@
+import type { RenderInput } from 'claude-code'
+
+import { BODY_ROWS } from './body-rows.js'
+import { COLUMNS } from './columns.js'
+
+/**
+ * A pane the plugin does not own, docked on a 160-column terminal at the
+ * view fixtures' body size.
+ *
+ * Its render passes beneath the plugin to the hook a test draws a view in.
+ */
+export const VIEW_PANE: RenderInput<'Pane'> = {
+  component: 'Pane',
+  surface: 'terminal',
+  requestId: 'view',
+  viewport: { columns: 160, rows: 40 },
+  props: {
+    title: 'View',
+    isFocused: false,
+    bodyColumns: COLUMNS,
+    placement: 'dock',
+    scroll: { offset: 0, bodyRows: BODY_ROWS },
+    view: {},
+  },
+}

mods/diff/tests/fixtures/pane-view/vs-spoofed.ts

@@ -0,0 +1,10 @@
+import type Git from '../../../hooks/git'
+
+/**
+ * A branch comparison whose base branch name hides a right-to-left
+ * override, to prove the view strips format characters.
+ */
+export const VS_SPOOFED: Pick<Git.DiffData, 'mode' | 'source'> = {
+  mode: 'branch',
+  source: { kind: 'branch', baseBranch: 'ma\u202Eniam', baseRef: 'abc' },
+}