## Why
Terminal probes and other bootstrap work can leave keys or partial control
sequences buffered before an interactive startup screen is visible. Those
inputs must not accidentally select or confirm an action, while typeahead
intended for the composer should survive terminal initialization.
## What changed
- Replay user input consumed by Unix startup probes through Crossterm while
filtering completed terminal color replies, and avoid consuming the Windows
console input queue when detecting default colors.
- Drain decoded and unread input after rendering actionable startup screens,
including onboarding trust, migration, update, provider, resume, and hooks
prompts. Keep incomplete control sequences quarantined and fail closed when
an input boundary cannot be resolved.
- Restore terminal modes if initialization exits early and bound terminal probe
reads by time and byte limits.
## Testing
Add parser, boundary, onboarding, and PTY coverage for preserved typeahead,
split escape sequences, bracketed paste, delayed input, and fresh input after
an interactive screen becomes ready.
GitOrigin-RevId: 321198996cdd88fe9b43c4a762e750bff450482c
Charlie Marsh
58d2daba45