Why: Process output folded on every text delta, successful tool
results disappeared after refresh, and generated files stayed plain
text instead of a card that opens a closable preview.
Evidence: npx tsc -b --noEmit (clean); npx vitest run (51 passed).
Impact: Live work stays expanded until the run ends, then folds to
one worked-time line. File cards open a per-conversation preview pane.
docx renders page by page, with mammoth if that fails.
Refs: feature/chat-timeline-preview
Co-authored-by: Cursor <cursoragent@cursor.com>
