fix: Enrich attachment-only task descriptions for title generation

[charlesvien]

Problem

Tasks created with only file attachments (pasted text or images) produce generic titles because the LLM has no meaningful text to work with.

Changes

1. Add enrichDescriptionWithFileContent to read attached file contents and build a meaningful description for the title generator
2. Fire onEmptyChange when attachments change so the editor correctly tracks emptiness
3. Move title generation from the creation saga to useChatTitleGenerator hook, generating on the first prompt instead
4. Pass a plain-text fallback as title on task creation so titles are never blank
5. Cap generated titles to 255 chars and skip the manual-set check on first generation
6. Add comprehensive tests for enrichDescriptionWithFileContent

How did you test this?

Manually

[charlesvien]

• fix: Downscale large images before attaching #1987
• feat: Show PR and diff status icons on task list items #1986
• fix: Reduce update check interval from 24h to 1h #1985
• fix: Debounce releases and skip empty tags in code workflow #1983
• fix: Fix stacked chevrons in project select dropdowns #1981
• fix: Enrich attachment-only task descriptions for title generation #1980 👈 (View in Graphite)
• main

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[greptile-apps]

Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 1
apps/code/src/renderer/utils/generateTitle.test.ts:75-94
**Prefer parameterised tests for fallback cases**

These three tests all verify that the `[Attached: <filename>]` hint is returned, and differ only in the setup (binary extension, read throws, read returns null). Per the project's testing conventions, these should be collapsed into a single `it.each` table.

```ts
it.each([
  {
    label: "binary file",
    description: '1. <file path="/tmp/screenshot.png" />',
    setup: () => {},
    expected: "[Attached: screenshot.png]",
  },
  {
    label: "read throws",
    description: '1. <file path="/tmp/missing.ts" />',
    setup: () => mockReadAbsoluteFile.mockRejectedValue(new Error("ENOENT")),
    expected: "[Attached: missing.ts]",
  },
  {
    label: "read returns null",
    description: '1. <file path="/tmp/empty.ts" />',
    setup: () => mockReadAbsoluteFile.mockResolvedValue(null),
    expected: "[Attached: empty.ts]",
  },
])(
  "falls back to filename hint — $label",
  async ({ description, setup, expected }) => {
    setup();
    expect(await enrichDescriptionWithFileContent(description)).toBe(expected);
  },
);
```

_{Reviews (1): Last reviewed commit: "Add tests for enrichDescriptionWithFileC..." | Re-trigger Greptile}

[charlesvien]

Merge activity

• May 4, 6:05 PM UTC: A user started a stack merge that includes this pull request via Graphite.
• May 4, 6:05 PM UTC: @charlesvien merged this pull request with Graphite.