feat(tui): pulse active subagent indicator

[ajzrva-sys]

Summary

Make the existing ⛓ N subagent indicator feel alive while delegated work is running.

• pulse only the chain glyph between the theme's muted and accent colors every 700 ms
• keep the glyph, count, and display width unchanged so the status bar never jitters
• mount the timer only while the indicator is visible and clean it up on unmount
• add focused coverage for the pulse color sequence

This keeps subagent activity glanceable without adding a persistent panel or more status text.

Verification

• npm test -- --run src/__tests__/appChromeStatusRule.test.tsx — 24 passed
• full vitest run — 1,459 passed, 4 skipped
• npm run typecheck — passed
• Prettier check for both changed files — passed
• independent Codex review — no actionable issues

Related

• Builds on the status-bar subagent indicator from feat(tui): subagent spawn observability overlay #14045 / feat: workload status bar + unified Ctrl+X panel for agents and processes #5625.
• Deliberately narrower than the persistent async delegation panel proposed in feat(tui): async delegation view — docked agents panel + live steering #70899.

[teknium1]

Thanks for keeping this focused on the existing status-bar signal. The premise holds: current main renders the active-subagent marker as a static muted ⛓ N at ui-tui/src/components/appChrome.tsx:693-696, after gating it on a positive active count at :557-558.

Suggested changes

• Consider adding an Ink-rendered fake-timer lifecycle test. The added test in PR commit f513870bae97 verifies only the pure color helper; current StatusRule tests invoke StatusRule(...) directly at ui-tui/src/__tests__/appChromeStatusRule.test.tsx:108-112, which does not mount the nested pulse component or run its interval/cleanup effect. A rendered test could cover the 700 ms transition and unmount cleanup.

The implementation is otherwise a localized fit: it preserves the existing glyph/count width reservation and only mounts under the existing showSubagents condition. This is an automated hermes-sweeper review.

[ajzrva-sys]

Closing at the author's request.