[selfcontained]

Behavior

The collapsed “Your last message” overlay now puts its label and message preview on one row at desktop widths, reducing its height. Long and multiline previews truncate inside the remaining space while previous/next buttons stay visible. Narrow screens retain the preview below the label.

Expansion, jump, Escape/focus, message navigation, attachments, overlay positioning, and the Chat options visibility preference retain their existing behavior. Only request-context presentation and component regression coverage changed.

Validation

• pnpm run check — passed.
• pnpm run finalize:web — passed.
• pnpm run test:e2e — 259 passed, 13 skipped.
• Focused component tests — 7 passed; commit formatting/lint/type-check hooks passed.
• Real isolated Playwright: submitted long multiline/unbroken text through the composer; desktop 1440px and 768px (448px pane), touch 390px and 320px; verified truncation, visible controls, expand/collapse, previous/next, jump, Escape focus and persisted visibility toggle. Desktop collapsed overlay measured 36px. Screenshots posted to the Dispatch task delivery stream; browser closed and LAN preview retained.
• Mapped owners: stream-delivery-owner and frontend-react-review both reported no findings. Original review records: 4e2e9392-723e-4fcd-b0b3-e1c0cb7f733e, 46a36540-cdf7-48ad-a544-0dabeaf4947a.

Task: tsk_572184872ea6. Merge held for acceptance/approval; review-column capacity hold remains.