Adds docs/research/alknet-channels/poc-plan.md — a standalone three-step POC
plan that derisks the channels layer in isolation (no call protocol, no real
transport, no real adapters):
- Step 1: chunk format + N-channel demux/mux — generalizes TTY's 5-byte
ChunkReader/ChunkWriter to the 9-byte format, validates decompose→stream→
recompose for 3+ concurrent channels with the sync-core/async-shell split
pattern from TTY's REQ-TTY-01.
- Step 2: per-channel Connection presentation — wraps each reassembled
channel as Connection::from_stream and runs a minimal echo ProtocolHandler
through the full path. Validates the existing Connection abstraction is
sufficient; no core changes needed for the POC.
- Step 3: tunnel handler — opens a TcpStream and pumps bidirectionally,
reusing TTY's pump_session shape with two pumps. Validates the same
concepts behind the TTY crate work as a generic port proxy.
Stretch goals: WASM build of the sync core, mixed channel types on one
connection, hub relay sketch with channel_id remapping.
Adds three open questions to phase-0-findings.md:
- OQ-CH-12: unknown channel_id on demux (lenient drop vs strict error).
- OQ-CH-13: core BidiStreamSource trait — additive refactor to make
ChannelConnection a first-class peer of QUIC (many bidi streams) rather
than a bag of yield-once Connections. Likely +EV; not needed for the POC
but should be evaluated in Phase 1.
- OQ-CH-14: client-side channels endpoint — the symmetric ChannelClient
type (analogue of AlknetEndpoint vs CallClient). After the POC we're
probably going to need some light refactoring to the core to make these
easier; mostly additive and not breaking in major/pita ways.
Updates phase-0-findings.md De-risk POC section to point at the detailed
plan and adds the poc-plan to References.