- Add GatewayMessage and JsonPayload interfaces to gateway.ts
- Type WebSocket message parsing with GatewayMessage instead of any
- Use ReturnType<typeof setTimeout> for timer refs
- Type chat event payload destructuring explicitly
- Add ChatPayloadMessage interface for extractText()
- Replace any casts in loadSessions/loadHistory with typed assertions
- Add str() helper in ToolCall.tsx for safe unknown→string extraction
- Use Extract<MessageBlock, ...> type guards instead of `as any` casts
- Type CodeBlock children prop properly