Add ConnectionKind::Stream: a single read/write pair behind a
Mutex<Option<...>> that accept_bi yields once (then ConnectionClosed).
Add Connection::from_stream(send, recv, alpn, remote_addr) and
Connection::from_bidi(stream, alpn, remote_addr) constructors.
Rename the stream-level SendStreamKind::Mock / RecvStreamKind::Mock to
::Stream (they were already generic Box<dyn AsyncRead/Write> — the
wrong name). Rename from_mock to from_stream.
Remove MockConnection trait + ConnectionKind::Mock entirely. Migrate
all alknet-call test StubConnections to use from_stream with
tokio::io::sink() + tokio::io::empty() (immediate EOF on the read side
causes handle_stream to exit cleanly, then accept_bi returns
ConnectionClosed and the run_loop exits).
The yield-once accept_bi contract: QUIC yields many streams, everything
else yields one. Handlers that loop (TtyAdapter) get one iteration per
single-stream connection; handlers that call once (HttpAdapter) get the
stream directly. Both correct, no branching on transport.
This unblocks TCP+TLS listeners, SSH channel dispatch, WebTransport
streams, and wasm — all via from_stream, all through the same
HandlerRegistry, zero handler code changes.
See docs/research/transport-generalization/findings.md for the full
trace and the yield-once contract.
glm-5.2
865fef6210