POC at /workspace/alktunnels-reverse-poc (14 tests, clippy/fmt clean,
repeat-run stable) over alkcall 0.6.0:
- The review 007 non-finding trace confirmed by execution: the hub
(accept side) opens tunnel channels toward a connect-side worker
serving its own open op (from_connection_with_serving +
ChannelOperations::register_on + post-hoc openable registration)
- ADR-047 §5 exercised in the Pub-like orientation: the worker
(connect side) allocates odd IDs; the hub adopts
- R-01 plan flow under concurrency: two same-resource opens, distinct
channels, distinct dialed handles — the forward POC's handoff race
is structurally gone
- OQ-TN-03's last open thread closed: no advertisement op needed —
the listener is the initiator's own local resource; a far-side
listener is a producer-side listen establisher over the same open op
- W4 EOF sentinel propagation validated (half-close semantics);
W3 adopter self-reaping pinned as a TunnelSession spec requirement;
W2 post-hoc registration viable
Findings:
- F-1: ChannelPlan's Send+Sync bound constrains plan payloads
(socket halves carry + Sync; spec should pin the constraint)
- F-2: empty UDP datagrams collide with the EOF sentinel in raw
pass-through (pinned by an executable test) — the length-framed
codec is mandatory for UDP; raw pass-through stays
stream-substrate-only. Second validation of the codec decision;
OQ-TN-02 mandate strengthened
W1 (connect-side serving path resolves caller identity only via
payload auth_token) filed upstream as alkcall consumer-findings
ledger CF-005 (alkcall 0d287a9).
Verification: cargo test 14/14, clippy --all-targets -D warnings,
fmt --check — all clean, repeat-run stable
17 tests pass (7 codec + 10 integration). The producer/consumer
shape, ADR-049 establishment integration, codec decision, and typed
establishment errors all validated over alkcall 0.5.0 channels.
Key findings folded into the ledger:
- OQ-TN-05 resolved for stream substrates: no backend trait —
pump_halves generic over boxed halves (TCP into_split, UDP
UdpHalf adapter); remaining thread is only the hub re-produce
composition question
- OQ-TN-06 convergence test satisfied: producer pump and consumer
pump are the same shape modulo channel side; extraction decidable
in Phase 1
- New finding for the alkcall ledger: OpenHandler JoinHandle
semantics are load-bearing and undocumented — a handler that
returns before the data plane starts tears the channel down at
birth (the POC found this by hanging; the pump must be awaited
inline). Plus: Establishment should carry the channel plan
(the reserved extension point) to kill the establisher handoff
side-channel
- UdpHalf truncation semantics flagged for the Phase 1 ADR
(recommend fail-loud over silent truncation)
POC crate: /workspace/alktunnels-udp-poc (db224cc).