perf

                    it->second.recv_fin_offset = final_size;

                }

                (void)app_error;

                retireStreamIfDone(sid);

                // Deliberately not retired here: the application may still

                // need to observe this via isStreamReset()/hasStreamData()

                // before it's done with the stream. It retires (and, for a

                // peer-initiated stream, grants fresh credit) once the app

                // calls closeStream(), same as any other completed stream.

            }

            break;

                uint64_t app_error = decodeVarInt(&data[offset], bytes);

                offset += bytes;

                auto it = _streams.find(sid);

                if (it != _streams.end()) {

                    // RFC 9000 §3.5: reset the stream in response so the

                    // peer can see our send side as done and retire it

                    // promptly, instead of waiting on a response it already

                    // told us it doesn't want.

                    if (!it->second.send_fin) {

                if (it != _streams.end() && !it->second.send_fin) {

                    // RFC 9000 §3.5: reset our send side in response so the

                    // peer isn't left waiting on a response it already told

                    // us it doesn't want. This is what lets retirement (and

                    // the peer's stream-count credit) happen promptly

                    // instead of only once our send finishes naturally,

                    // which for an abandoned/redundant fetch may be slow or

                    // never happen at all. resetStream() retires this side

                    // itself once both directions are terminal.

                    resetStream(sid, app_error);

                }

                    retireStreamIfDone(sid);

                }

            }

            break;

            stream.recv_ranges.clear();

        }

    }

    // The peer's FIN just arrived on this stream. If our own side already

    // finished sending (send_fin set earlier via closeStream/resetStream),

    // this is the event that completes the pair — retire it now instead of

    // relying on the local application to call closeStream() again for a

    // stream it may already consider done.

    if (has_fin) {

        retireStreamIfDone(stream_id);

    }

    // Deliberately not retired here even once has_fin is set: the

    // application (client polling via hasStreamData/recvStreamData, or a

    // server callback not yet dispatched) may still need this stream's

    // buffered data. It retires once the app calls closeStream(), same as

    // any other completed stream.

}

// ============================================================================