Iter 29. Wires rumqttc::MqttOptions::set_last_will so the broker
auto-publishes "offline" on ruview/<node>/bfld/availability (retained,
QoS 1) when the publisher's TCP session drops without a clean
DISCONNECT. Closes the iter-28 lifecycle loop: explicit "online" on
connect + LWT-driven "offline" on session loss + explicit "offline"
on graceful shutdown.
Added (in src/rumqttc_publisher.rs, gated on `feature = "mqtt"`):
- RumqttPublisher::connect_with_lwt(node_id, opts, capacity) -> (Self, Connection)
Convenience wrapping with_lwt(opts, node_id) then Self::connect(opts, capacity).
- with_lwt(opts, node_id) -> MqttOptions free helper for operators who
build their own opts (custom TLS, credentials) and want to opt in to
the LWT without using the connect_with_lwt shortcut.
- rumqttc 0.24 LastWill::new(topic, message, qos, retain) — 4-arg form;
retain = true so HA sees "offline" on next start even if it was down
when the session dropped.
- pub use with_lwt, RumqttPublisher from lib.rs
tests/rumqttc_lwt.rs (8 named tests, all green, gated on mqtt):
with_lwt_returns_options_without_panic
connect_with_lwt_constructs_publisher_and_connection
connect_with_lwt_uses_documented_availability_topic
(constructive proof — both LWT and discovery use the same
availability_topic() function so they can't drift)
connect_with_lwt_publisher_still_publishes_state_topics
(LWT is purely additive — state topics work as before)
publisher_trait_object_constructible_with_lwt_path
with_lwt_is_idempotent_against_double_call
(rumqttc replaces the will silently — useful for wrapper libraries)
caller_built_options_can_opt_in_via_with_lwt_then_pass_to_connect
(operator pattern: build opts with TLS/creds, attach LWT, then connect)
placeholder_topicmessage_path_unaffected_by_lwt
Test bug caught:
- Initial test asserted 4 topics for Anonymous + no zone; actual is 5
(presence + motion + person_count + confidence + identity_risk).
rf_signature_hash is a BfldEvent JSON field, not its own MQTT topic.
Fixed the assertion; documented the distinction in the test comment.
ACs progressed:
- ADR-122 §2.2 availability surface now fully operational. Three paths:
1. Explicit publish_availability_online (iter 28) on connect
2. LWT auto-publishes "offline" if connection drops (this iter)
3. Explicit publish_availability_offline (iter 28) on graceful stop
HA reads the same topic in all three cases; entities grey out
device-wide via the iter-28 discovery `availability_topic` field.
Test config:
- cargo test --no-default-features → 72 passed
- cargo test → 203 passed
- cargo test --features mqtt → 220 passed (212 + 8 new)
Out of scope (next iter target):
- GitHub Actions workflow with mosquitto Docker service. With iter
24+29 now both depending on a live broker for full coverage, the
CI lift is the next highest-value step.
- Three operator-ready HA blueprints (ADR-122 §2.6): presence-driven
lighting, motion-aware HVAC, identity-risk anomaly notification.
Co-Authored-By: claude-flow <ruv@ruv.net>
74807a60c8