- Split 1504-line monolithic main.tsx into 5 utility modules: - src/utils/tool-maps.ts (TOOL_GROUPS, TOOL_TO_UI, MODEL_OPTIONS, QUICK_PROMPTS) - src/utils/input-handling.ts (keyboard shortcuts, textarea, event listeners) - src/utils/thread-management.ts (deduplication, thread helpers) - src/utils/message-rendering.ts (tool call extraction, UI matching) - src/utils/api-client.ts (LangGraph API client operations) - Add missing deps: unist-util-visit, hast - Update agent model configs (opus for backend, haiku for tester) Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>