[Cleanup] Extract duplicate mention tabs array in ChatInput handleKeyDown

[samzong]

Problem

ChatInput/index.tsx constructs the exact same tabs array twice in handleKeyDown — once for ArrowRight/Tab and once for ArrowLeft:

Location

File: packages/desktop/src/renderer/components/ChatInput/index.tsx:240-257

// Line 240-245 (Tab/ArrowRight handler)
const tabs: MentionTab[] = [
  ...(mentionAgents.length > 0 ? (['agents'] as const) : []),
  ...(contextFolders.length > 0 ? (['local'] as const) : []),
  'tasks', 'files',
];
setMentionTab((cur) => tabs[(tabs.indexOf(cur) + 1) % tabs.length]);

// Line 252-257 (ArrowLeft handler) — IDENTICAL array
const tabs: MentionTab[] = [
  ...(mentionAgents.length > 0 ? (['agents'] as const) : []),
  ...(contextFolders.length > 0 ? (['local'] as const) : []),
  'tasks', 'files',
];
setMentionTab((cur) => tabs[(tabs.indexOf(cur) - 1 + tabs.length) % tabs.length]);

Fix Approach

Extract to a useMemo constant outside handleKeyDown:

const mentionTabs = useMemo<MentionTab[]>(() => [
  ...(mentionAgents.length > 0 ? (['agents'] as const) : []),
  ...(contextFolders.length > 0 ? (['local'] as const) : []),
  'tasks', 'files',
], [mentionAgents.length, contextFolders.length]);

Then reference mentionTabs in both handlers.

Verification

1. Run pnpm check — must pass
2. Open mention picker, Tab/ArrowRight/ArrowLeft between tabs — should cycle correctly

Context

• WG: UI & Design System
• Priority: Low (good first issue)
• Estimated effort: ~10 minutes

[github-actions]

Hi @samzong,
Thanks for opening an issue!
We will look into it as soon as possible.

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[reverb256]

I'd like to pick this up. Planning to submit a PR shortly.