mods: revert two changes (agents-md truncated reads, diff forced colors) (#98018)

* Revert "agents-md: the truncated-read tests laid out as the formatter lays them"

* Revert "fix(agents-md): retain instructions after truncated reads"

* Revert "diff: the shared diff arguments' doc says what --no-color pins"

* Revert "fix(diff): preserve hunks when Git forces colored output"

mods/agents-md/hooks/register.ts

@@ -223,14 +223,7 @@ export function register(on: On, options: PluginOptions): void {
       ...Files.filesOf(claude),
     ]).filter(file => !sent.has(file.path))
     const attached = fresh.filter(file => !Frames.isFileAt(file, read))
-    const output = result.result
-    const isPartialText =
-      output?.type === 'text' &&
-      (output.file.truncatedByTokenCap ||
-        output.file.startLine !== 1 ||
-        output.file.numLines < output.file.totalLines)
-    const isWholeRead =
-      e.offset === undefined && e.limit === undefined && !isPartialText
+    const isWholeRead = e.offset === undefined && e.limit === undefined
 
     for (const file of fresh) {
       const isSent =

mods/agents-md/tests/register.test.ts

@@ -1,4 +1,4 @@
-import { describe, expect, mock, test, tier } from 'claude-code/testing'
+import { describe, expect, test, tier } from 'claude-code/testing'
 
 import Hooks from '../hooks'
 import Fixtures from './fixtures'
@@ -84,79 +84,6 @@ describe('register', () => {
     ).toEqual({ blocks: BLOCKS, instructionFiles: [] })
   })
 
-  for (const [name, args, file, attaches] of [
-    [
-      'an auto-paginated read',
-      {},
-      { content: '# head\nfollow', truncatedByTokenCap: true },
-      true,
-    ],
-    ['an incomplete line range', {}, { content: '# head', numLines: 1 }, true],
-    ['a complete read', {}, {}, false],
-    [
-      'an explicit limit',
-      { limit: 1 },
-      { content: '# head', numLines: 1 },
-      true,
-    ],
-    [
-      'an explicit offset',
-      { offset: 2 },
-      { content: 'follow the tail rule', numLines: 1, startLine: 2 },
-      true,
-    ],
-    ['an unstructured result', {}, undefined, false],
-  ] as const) {
-    test(`a nested AGENTS.md after ${name}`, async ($, on) => {
-      const dir = `${Fixtures.SESSION.cwd}/nested`
-      const path = `${dir}/AGENTS.md`
-      const content = '# head\nfollow the tail rule'
-      const started = Fixtures.projectOf(
-        on,
-        [Fixtures.ancestorOf(dir, 'AGENTS.md', content)],
-        [],
-      )
-
-      mock.env(on, {})
-      on('session.cwd', () => ({ value: Fixtures.SESSION.cwd }))
-      on('tool.call', ($, e) => ({
-        result:
-          e.tool === 'Read' && file !== undefined
-            ? {
-                type: 'text',
-                file: Object.assign(
-                  {
-                    filePath: e.file_path,
-                    content,
-                    numLines: 2,
-                    startLine: 1,
-                    totalLines: 2,
-                  },
-                  file,
-                ),
-              }
-            : 'read',
-      }))
-
-      const direct = await $.tool.call({
-        tool: 'Read',
-        file_path: path,
-        ...args,
-      })
-      const source = { tool: 'Read', file_path: `${dir}/source.ts` } as const
-      const after = await $.tool.call(source)
-      const repeated = await $.tool.call(source)
-
-      expect(direct.context).toBeUndefined()
-      expect(after.context).toEqual(
-        attaches ? [`Contents of ${path}:\n\n${content}`] : undefined,
-      )
-      expect(repeated.context).toBeUndefined()
-
-      await started.clock.settle()
-    })
-  }
-
   test(
     'the start sends the mode row alone: no walk, no toast',
     { plugins: [Fixtures.RECORDING] },

mods/diff/hooks/git/argv/diff-leading-args.ts

@@ -4,9 +4,7 @@
  *
  * Root-relative paths whatever `diff.relative` says, non-ASCII paths as
  * their own bytes, no optional locks, no child `git status` in a dirty
- * submodule, no external diff or textconv driver even on a stats pass, and
- * no color escapes whatever `color.ui` or `color.diff` says, so a hunk
- * header parses where either is set to `always`.
+ * submodule, and no external diff or textconv driver even on a stats pass.
  */
 export const DIFF_LEADING_ARGS = [
   '--no-optional-locks',
@@ -15,7 +13,6 @@ export const DIFF_LEADING_ARGS = [
   '-c',
   'core.quotePath=false',
   'diff',
-  '--no-color',
   '--no-ext-diff',
   '--no-textconv',
   '--ignore-submodules=dirty',

mods/diff/tests/git/fetch-diff.test.ts

@@ -148,42 +148,6 @@ describe('fetch-diff', () => {
     ).toBe(true)
   })
 
-  test("forced git colors do not hide a changed file's hunks", async () => {
-    const deps = depsOf({
-      'HEAD --shortstat': Fixtures.ok(
-        ' 1 file changed, 1 insertion(+), 1 deletion(-)',
-      ),
-      'HEAD --numstat': Fixtures.ok('1\t1\ta.ts\0'),
-      'ls-files': Fixtures.ok(),
-    })
-
-    const git = Fixtures.scriptedGitOf({
-      '--no-color': Fixtures.ok('@@ -1 +1 @@\n-old\n+new\n'),
-      diff: Fixtures.ok(
-        '\x1b[36m@@ -1 +1 @@\x1b[m\n\x1b[31m-old\x1b[m\n' +
-          '\x1b[32m+\x1b[m\x1b[32mnew\x1b[m\n',
-      ),
-    })
-
-    const outcome = await Git.fetchDiff(deps, 'uncommitted')
-    const data = outcome.kind === 'data' ? outcome.data : null
-    const [row] = data?.files ?? []
-
-    expect(data?.stats).toEqual({
-      filesCount: 1,
-      linesAdded: 1,
-      linesRemoved: 1,
-    })
-
-    expect(
-      data && row ? await Git.fetchFileHunks(git.run, data, row) : null,
-    ).toEqual({
-      hunks: [{ oldStart: 1, newStart: 1, lines: ['-old', '+new'] }],
-      isTruncated: false,
-      isLarge: false,
-    })
-  })
-
   test('uncommitted mode drops pre-session untracked files', async () => {
     const outcome = await Git.fetchDiff(
       depsOf(