[Bug] Desktop: Pasting hundreds of files causes app hang; missing confirmation and virtualized rendering

Bug Description
Title: [BUG] Desktop: pasting hundreds of files (Ctrl+A in Finder) gets no confirmation; session then hangs the app on every load What's wrong: Accidentally copied entire Downloads folder (several hundred files) and pasted into the composer. No confirmation prompt. The app froze trying to render hundreds of attachment chips, and after restart it hung again every time the session loaded — the unsent draft persisted and re-rendered. App was effectively unusable until the session transcript (18 MB jsonl) was manually moved out of ~/.claude/projects/. Expected: A confirmation when pasting more than N files ("Attach 412 files?"), and/or virtualized rendering of attachment chips so a large draft can't hang the app. Environment: macOS, Claude Code desktop app, Claude 1.11847.5 (9692f0) 2026-06-09T17:34:27.000Z

Environment Info

• Platform: darwin
• Terminal: Apple_Terminal
• Version: 2.1.172
• Feedback ID: f3838277-9832-4a13-9164-0b8b4687b9b1

Errors

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