**Highlights:**
- **Callback Chaining:** Now supports a list of before and after callbacks, as in the non-live version. Callbacks are executed in order, stopping when one returns a response.
- **Unit Tests:** Added new unit tests for before and after callbacks, async and sync versions, callback chains and mixed callbacks.
- **Sample Agent:** Introduced a new example agent with multiple callbacks showing various behaviors: audit, security, validation, and enhancement. This provides practical usage examples.
PiperOrigin-RevId: 783884562
George Weale
Hangfei Lin