Consolidate markdown rendering logic into dedicated assistant-ui components and update syntax highlighting to use Shiki with GitHub themes. Removes dependency on react-markdown and react-syntax-highlighter in favor of @assistant-ui/react-markdown with Shiki-based highlighting.
- Refactor HappyComposer settings overlay to conditionally render permission and model settings based on their availability
- Add showPermissionSettings and showModelSettings flags for cleaner conditional rendering
- Enhance ToolMessage fallback UI with styled card layout and code blocks for arguments and results
- Improve type validation in isToolCallBlock with comprehensive property checks
- Add safeStringify utility for robust JSON serialization with fallback handling
weishu