Smooth agent chat state transitions

[SergeSerb2]

Summary

• Stabilize the live agent activity dock with reserved phase, tool-tape, and timer geometry so state changes no longer make the transcript breathe sideways.
• Crossfade command completion and decision-submission states inside fixed-size regions while preserving Reduce Motion behavior.
• Track in-flight approval and user-input responses in the model to acknowledge clicks immediately and prevent duplicate provider submissions.
• Preserve the existing streaming timeline safeguards: high-frequency token and row-layout updates remain intentionally unanimated to avoid scroll jitter and LazyVStack blanking.

Area

• apps/mac — Native macOS app
• apps/server — Local server and orchestration
• apps/mobile — Expo / React Native companion
• apps/windows — Windows desktop app
• packages/* — Shared contracts, runtime, or utilities
• Other

Verification

• T3_SERVER_TEST_WORKERS=3 pnpm run verify --all
• pnpm run test:mac --filter approvalResponseState
• Mock UI probe captures inspected for approval cards, command task cards, and the live activity dock

The final full gate passed all five steps, including 1,678 TypeScript tests and 722 macOS tests. The UI probe wrote all target chat captures; its later unrelated settings cleanup exited after those captures were complete.

Screenshots / Recordings

Not attached. The target chat surfaces were inspected from the debug-only in-process UI probe captures; the visible changes are primarily transitions between states.

Release notes

Smoother agent activity, command completion, and decision-card transitions in macOS chat.