## What changed
- Add an optional `turnTrigger` field to app-server `turn/start` requests and
expose it in the generated protocol schemas.
- Propagate non-empty trigger values to Responses request metadata as the
reserved `turn_trigger` field, while preserving the original value when a
request steers an active turn.
- Classify turns started by queue dispatch, goal continuation, retry recovery,
and realtime handoff.
## Testing
- Cover HTTP and WebSocket metadata forwarding, steering behavior, reserved
metadata handling, and the built-in trigger classifications.
GitOrigin-RevId: c12fe2c522286db21b76081ae6154fbf6bfb3639
pakrym-oai
538900ee76