- docs/architecture/README.md: add Roles and Composition section with
the four roles (producer, consumer, hub, spoke), dependency layering
diagram, protocol crate pattern, and the two-path adapter model
- docs/architecture/channels-overview.md: fix stale alknet ADR numbers
(071/072/073/074/075/076/077/078/079/080/081 -> 034-044), update
relationship section for post-extraction world, update crate
dependencies to reflect single-crate alkcall
- src/lib.rs: add Downstream composition section with role table and
protocol crate pattern, linking to the architecture README
Verification: cargo test (483 passed), cargo clippy (clean),
cargo fmt (clean), cargo doc (no warnings)
C-04 [critical]: route_payload is now async — uses send().await instead
of try_send, so the demux stalls on a full buffer instead of dropping
chunks. Lossless bounded-buffer backpressure per ADR-040 REQ-CH-05.
C-05 [critical]: DEFAULT_BUFFER_CAP changed from 1,048,576 (messages)
to 64 (messages). The old value counted messages, not bytes, giving a
~16 TiB per-channel bound instead of the intended 1 MiB. The new value
is a reasonable message-count bound; the actual memory bound is
enforced by the 16 MiB MAX_CHUNK_LEN per message.
C-07 [critical]: demux loop now skips the payload bytes on
ChunkError::TooLarge before continuing. The parsed length is in the
error variant; the demux reads and discards that many bytes, then
resyncs on the next 8-byte header. Previously it continued without
skipping, causing permanent stream desync.
C-16 [major]: MpscSendStream switched from tokio::sync::mpsc to
futures::channel::mpsc, which exposes poll_ready for proper async
backpressure in poll_write. The ~50 lines of abandoned deliberation
comments are removed. The mux pump now uses futures::StreamExt::next
instead of tokio recv.
C-17 [major]: mux pump writes an EOF chunk when the receiver ends
without a sentinel (handler dropped without shutdown). Previously
the pump exited silently on recv→None, leaving the remote handler
hanging until full transport close.
Tests added:
- C-25 #2: demux_resyncs_after_oversized_chunk
- C-25 #3: backpressure_slow_reader_no_data_loss_other_channel_unaffected
- C-25 #6: mux_pump_writes_eof_on_implicit_close
Verification: 441 tests pass (was 439; +3), clippy clean, fmt clean,
doc warnings unchanged (2 pre-existing, Unit 6 long-tail).
deepseek-v4-pro