Verify scroll-to-bottom on message submit across all edge cases

[BunsDev]

Summary

Auto-scroll to bottom is implemented (ChatView.tsx lines 2526-2527 call forceStickToBottom() on submit), but edge cases may not be covered. Needs verification in browser tests.

Scenarios to verify

• User scrolled up, then submits a message → should scroll to bottom
• Optimistic message renders → should scroll to bottom
• Streaming response starts → should stick to bottom if user hasn't scrolled up
• Long message that extends past viewport → should scroll fully to bottom
• Multiple rapid submissions → should scroll to bottom after each

Current implementation

• chat-scroll.ts — isScrollContainerNearBottom() with threshold logic
• ChatView.tsx — shouldAutoScrollRef.current = true + forceStickToBottom() on submit
• scheduleStickToBottom() using requestAnimationFrame

Context

From TODO.md — "Submitting new messages should scroll to bottom". Implementation exists but needs edge-case validation. Consider adding Playwright browser tests.

🤖 Filed by Claude Code