## What changed
Make `ModelRequestContributor::budget_exhausted` return an `ExtensionFuture` and await budget checks before HTTP and WebSocket generation. WebSocket warmup continues to skip budget checks.
If the account changes during the post-connect budget check, rebuild the request setup and reconnect before sending the WebSocket request.
## Testing
Update tests to cover a pending budget check that resolves to exhaustion, warmup connection reuse, and an account switch while the post-connect budget check is awaiting completion.
GitOrigin-RevId: 462c74b86a46a4b2276f901c69187fc7cbc3ff81
## What changed
Add a default `ModelRequestContributor::budget_exhausted` hook and fail generation with `SessionBudgetExceeded` when any contributor reports an exhausted budget for the thread.
Check budgets before HTTP requests and before WebSocket connection setup, then check again after the connection is established. WebSocket warmup remains available when the budget is exhausted.
## Testing
Add coverage for budget changes during a tool call, verifying that exhaustion prevents the next model request while an available budget allows completion. Extend WebSocket coverage to verify that exhausted generation opens no connection and warmup still permits connection reuse once the budget becomes available.
GitOrigin-RevId: 97ce02dc7f9bd54830e4b73c4f0334a30367eebf
## 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
rhan-oai