fix(cli): restore debounced static UI refresh on terminal width changes - #29644

Summary

Restores the debounced refreshStatic() effect on terminalWidth changes in AppContainer.tsx (using a 100ms debounce) so that horizontal terminal resize events in default inline rendering mode clear wrapped frame remnants (ansiEscapes.clearTerminal) and remount the <Static> history region at the updated column width.

Details

• packages/cli/src/ui/AppContainer.tsx:
  • In default inline mode (ui.useAlternateBuffer: false and ui.terminalBuffer: false), narrowing the terminal width causes full-width lines in the dynamic Composer region (────, ▄▄▄▄, ▀▀▀▀) to soft-wrap across multiple physical terminal rows. Because Ink's log-update renderer erases previousLineCount logical lines rather than the wrapped physical row count, the top portion of the previous dynamic frame remains in scrollback during resize events.
  • Restores isInitialMount (useRef(true)) and a 100ms debounced useEffect watching [terminalWidth, refreshStatic] to clear the terminal and increment historyRemountKey once horizontal resizing settles.
  • Scopes the dependency array strictly to terminalWidth (excluding terminalHeight) so vertical-only terminal dimension changes (such as mobile virtual keyboard toggles) do not trigger <Static> remounts.
• packages/cli/src/ui/AppContainer.test.tsx:
  • Adds unit test coverage verifying that AppContainer skips refreshStatic() on initial mount and on height-only dimension changes, debounces rapid terminalWidth updates by 100ms, and writes ansiEscapes.clearTerminal while incrementing historyRemountKey in default inline mode.

Related Issues

How to Validate

1. Run the AppContainer unit test suite:

   npm test -w @google/gemini-cli -- src/ui/AppContainer.test.tsx

2. Manually start Gemini CLI in default inline mode, type a prompt into the input box, resize the terminal window horizontally, and verify that after 100ms the terminal clears any wrapped line remnants and re-renders cleanly at the new width.

Pre-Merge Checklist

• Updated relevant documentation and README (if needed)
• [ x] Added/updated tests (if needed)
• Noted breaking changes (if any)
• [ x] Validated on required platforms/methods:
  • MacOS
    • npm run
    • npx
    • Docker
    • Podman
    • Seatbelt
  • Windows
    • npm run
    • npx
    • Docker
  • [ x] Linux
    • [ x] npm run
    • npx
    • Docker