[flamboh]

Fix for the redesign stack, targets layer 2 (#28840).

Note

🤖 GPT-6.1 Sol on behalf of Oliver

Typing or backspacing in the @ menu drops file results while each search runs, briefly collapsing the menu and moving the highlight. Keep the last result list during the next search, replace it when the response settles, and preserve the highlighted item when it remains available. Mention groups keep the same order across queries.

The retained list clears when the mention, environment, workspace, thread, or question attachment changes. Shared web and desktop composer behavior is covered; native mobile and the wire contracts are unchanged. This touches the menu section of ChatComposer, away from the footer measurement changes in #31401 and spacer sizing in #30568.

Validation

• Failing-first regressions for pending results, group order, and highlight retention; all five focused tests pass.
• vp run check:changed origin/maria/redesign/2-composer-timeline.
• Integrated browser verification remains pending: Boat was at capacity; local pairing navigation was rejected by automatic approval review, and the plain dev URL returned HTTP 431. The isolated server was stopped.
• Independent reviews remain for the coordinating parent agent.

Before / after

Captures pending.

Implemented with GPT-6.1 Sol through the Codex harness.