## Why
Steering an active WebSocket response previously dropped the connection and
resent the full history. Draining the response preserves the connection and
allows the follow-up request to continue with `previous_response_id`.
## What changed
- Drain WebSocket responses when steering. For models using
`use_responses_lite`, first send `response.interrupt` with
`mode: "discard_partial_items"` once the response ID is available.
- Treat `response.incomplete` with reason `interrupted` as completion with
`end_turn: false`, preserving token usage and allowing the turn to continue.
Other incomplete reasons remain errors.
## Testing
Update the steering integration test to cover completed and discarded reasoning
items, asserting connection reuse, incremental follow-up input, and token usage
from the interrupted response.
GitOrigin-RevId: bc714b713e797cf1a67e3b26ffbf7664cb92eb33
## What changed
Add `ModelRequestContributor` and `ModelResponseInterceptor` to the extension API. Contributors can add filtered `client_metadata` without overwriting existing or reserved fields and create interceptors for individual requests.
Wire contributors into HTTP and WebSocket requests, distinguishing generation from warmup. Apply response interceptors in registration order before tracing and response bookkeeping so transformed output is recorded consistently. Interceptors can inspect, buffer, or transform events, with stream ownership carrying request state and cancellation.
## Testing
Add tests for metadata protection, incremental event transformation, interceptor ordering, upstream cancellation, and consistency between delivered output, traces, and WebSocket bookkeeping. Integration tests cover output gating and interruption over HTTP and WebSocket, including a contributor that bypasses gating for warmup requests.
GitOrigin-RevId: d4bc1745d2cacf8636728dbc0a58ab9f250e9392
pakrym-oai