Stream errors

Streams have two failure phases: establishment, returned from Client.Stream, and consumption, returned by StreamReader.Next.

Reader

StreamReader returns StreamReaderError for a nil reader, missing Next, or invalid framing adapter. A non-EOF error from the underlying reader moves it to a failed terminal state after draining what was already decoded: chunks buffered from an earlier frame, or returned alongside the error itself, are delivered first, and every later Next then returns that same latched error without reading another frame. A StreamResultError means the codec’s terminal-metadata producer itself failed, so the stream did not reach clean EOF and Result is unavailable. Terminal usage is not validated.

chunk, err := reader.Next()
if err != nil && !errors.Is(err, io.EOF) {
	var resultErr *stream.StreamResultError
	if errors.As(err, &resultErr) {
		// Terminal metadata was not authorized.
	}
	return err
}
_ = chunk

Provider

After a successful HTTP status, a dialect may emit StreamAPIError from an in-stream error event. It is terminal and is not converted into a clean result. Malformed or unknown events are skipped only where that codec documents tolerant event decoding; a missing terminal marker leaves Result unavailable.

Source and proof

• stream/result.go
• stream/stream.go
• openairesponses/errors.go
• anthropicapi/stream.go

Run go test ./stream ./codec/....