Split 1021-line index.ts into 10 focused modules per project conventions.
New structure:
- error-classifier.ts: error analysis with dynamic status code extraction
- agent-resolver.ts: agent detection utilities
- fallback-state.ts: state management and cooldown logic
- fallback-models.ts: model resolution from config
- auto-retry.ts: retry helpers with mutual recursion support
- event-handler.ts: session lifecycle events
- message-update-handler.ts: message.updated event handling
- chat-message-handler.ts: chat message interception
- hook.ts: main factory with proper cleanup
- types.ts: updated with HookDeps interface
- index.ts: 2-line barrel re-export
Embedded fixes:
- Fix setInterval leak with .unref()
- Replace require() with ESM import
- Add log warning on invalid model format
- Update sessionLastAccess on normal traffic
- Make extractStatusCode dynamic from config
- Remove unused SessionErrorInfo type
All 61 tests pass without modification.
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
