# Streaming failures

Detect incomplete SSE streams and terminal errors after HTTP headers are sent.

An SSE request can receive HTTP `200` and still fail later. Once headers are sent, HTTP does not allow the server to replace the status line with `502` or `504`.

## Detect completion

- Chat Completions should reach a terminal choice and `[DONE]`.
- Responses should reach `response.completed`; `response.failed` or an error event is terminal failure.
- Anthropic Messages should reach `message_stop`.

If the socket closes without the protocol's normal terminal event, mark the result incomplete. Do not silently treat accumulated text as a complete answer.

## Retry decisions

Retrying a pure text request is usually safe but can return different content. For tool workflows, track whether a complete tool call was received and whether the tool executed. Never execute partial JSON arguments.

Use an application deadline long enough for reasoning pauses, while keeping a separate idle timeout to detect dead connections. Preserve the response request ID when available.