bugfix

		// If a stream has terminated in both directions (FIN/RESET on both

		// send and recv sides), erase it and — for a peer-initiated stream —

		// grant the peer fresh stream-count credit via MAX_STREAMS. Called

		// from every place a stream's send_fin/recv_fin can flip to true

		// (closeStream, resetStream, and STOP_SENDING/RESET_STREAM/STREAM

		// frame processing) so retirement fires as soon as both sides agree

		// the stream is done, regardless of which side notices last.

		// only from closeStream() and resetStream() — i.e. once the

		// application itself is done with the stream — never from passive

		// incoming-frame processing, since the application may still need

		// to read buffered data or check isStreamReset()/hasStreamData()

		// after a STREAM/RESET_STREAM frame updates send_fin/recv_fin.

		void retireStreamIfDone(uint64_t stream_id);

		// Loss detection and retransmission