Pressing ArrowUp on an empty #message composer restores the last sent user text, matching common chat-app UX (Slack, Discord, ChatGPT).
- Read from #chat-history .msg-user dataset.raw (same path as resend/regenerate), not session sidebar metadata
- Literal empty check (whitespace-only drafts are preserved); ignore Shift/Alt/Ctrl/Meta and IME composition
- Extract wiring to composerArrowUpRecall.js; rAF + 250ms retry only (no global MutationObserver)
- Add tests/test_composer_arrow_up_recall_js.py
Co-authored-by: Cursor <cursoragent@cursor.com>
