fix(desktop): prevent "Composer is not available" error on boot after v0.17 upgrade

[Andy365-365]

What does this PR do?

Add a defensive safeSetText wrapper around aui.composer().setText() in composer/index.tsx. When the assistant-ui composer core binding is not yet established (e.g. during boot or session switch), setText throws "Composer is not available". The wrapper catches this specific error and defers the call to the next frame via requestAnimationFrame, giving the binding time to resolve. Other errors rethrow normally.

Related Issue

Fixes #49903

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 🔒 Security fix
• 📝 Documentation update
• ✅ Tests (adding or improving test coverage)
• ♻️ Refactor (no behavior change)
• 🎯 New skill (bundled or hub)

Changes Made

File: apps/desktop/src/app/chat/composer/index.tsx (+28 lines, -5 lines)

• Added safeSetText — a useCallback wrapper that catches "Composer is not available" and retries on the next frame
• Replaced aui.composer().setText() with safeSetText() in:
  • clearDraft — clears composer on session switch
  • loadIntoComposer — restores draft text on mount / session switch
  • insertText — external text injection (defensive)
  • insertInlineRefs — inline ref insertion (defensive)
• Updated clearDraft's useCallback dependency from [aui] to [safeSetText]

How to Test

1. Upgrade from v0.16.0 to v0.17.0 (or set localStorage.setItem('hermes.desktop.composerPopout.enabled', 'true'))
2. Launch Hermes Desktop
3. Verify the composer input is responsive — no "Composer is not available" in DevTools Console
4. Switch between sessions — composer should load draft text without errors
5. Paste text, use voice input, trigger /slash commands — all interactions work normally

Checklist

Code

• I've read the Contributing Guide
• My commit messages follow Conventional Commits (fix(scope):, feat(scope):, etc.)
• I searched for existing PRs to make sure this isn't a duplicate
• My PR contains only changes related to this fix/feature (no unrelated commits)
• I've run pytest tests/ -q and all tests pass
• I've added tests for my changes (N/A: the bug requires assistant-ui core binding to be unresolved at boot, which cannot be reproduced in an isolated test environment)
• I've tested on my platform: Ubuntu 24.04

Documentation & Housekeeping

• N/A — no documentation, config, or architecture changes needed

Screenshots / Logs

N/A — the fix prevents a console error, no visual change.

[teknium1]

Thanks for the focused desktop investigation. This automated hermes-sweeper review found that the requested behavior is already implemented on current main.

• PR fix(desktop): guard composer mutations when the composer core isn't bound (#49903) #51728 merged the bug(desktop): v0.17.0 throws "Uncaught Error: Composer is not available" — input becomes unresponsive after upgrade #49903 composer-core guard as 281a439ad483e6f130c2305a5e932c652778cb3b.
• The current guarded mutation path is in apps/desktop/src/app/chat/composer/hooks/use-composer-draft.ts:65-77; draft restore, clearing, external inserts, and inline references use it at :179-191 and :264-288.
• apps/desktop/src/app/chat/composer/composer-text-guard.test.tsx:80-105 covers both the unbound no-throw case and normal bound writes.
• The additional preview-pane behavior in this PR is also present: apps/desktop/src/store/preview.ts:122-141 opens the pane before selecting the live preview tab.
• The merged composer fix shipped no later than v2026.7.1 (Hermes Agent v0.18.0).

Closing as implemented on main.