## What changed
- Add optional `websocketRequestId` to `environment/add` and send it as `X-Request-ID` on direct WebSocket upgrades, including reconnects. It requires a secure transport or a loopback destination.
- Echo a supplied `X-Request-ID` in the exec-server WebSocket upgrade response.
## Testing
Add coverage for `websocketRequestId` serialization and for handshake header forwarding and echoing, both with and without a request ID.
GitOrigin-RevId: 235303ff7e1150405b7e1158d6024223144e0cc3