feat(dbc): CAN message flows as AADL ports + bus-bound connections (REQ-INGEST-DBC-FLOWS-001)

[avrabe]

What

First feature of the v0.20.0 ingest track. Extends DBC ingest (REQ-INGEST-DBC-001, v0.17.0) to model per-message dataflow on top of the existing bus + devices + frame-data-types model.

Each CAN frame now becomes:

• an out event data port on its BO_ transmitter node,
• an in event data port on every SG_ receiver node (union of the frame's signal receiver lists),
• joined by port connections, each carrying Deployment_Properties::Actual_Connection_Binding => (reference (can_bus)).

Event-data ports model the discrete, data-carrying CAN frame; one broadcast out port fanning out to several in ports mirrors CAN's one-to-many. A frame is wired only when it has both a known transmitter and ≥1 known receiver (the Vector__XXX placeholder and unknown names are dropped) — so no port is left dangling. Frames lacking either end still emit their data type, unchanged.

Scope — faithful CAN modelling, not a network-calculus feeder

These connections are for traceability, diagrams and codegen. They are not wired into spar's FIFO TFA/PLP network-calculus engine: CAN is priority-arbitrated, not FIFO, so a FIFO bound over it would be unsound. The CAN bus carries no Spar_Network::Switch_Type, so extract_network_graph correctly ignores it (consistent with REQ-NC-BRIDGE-001, which already excludes CAN). CAN response-time analysis remains a separate Tindell track behind its own soundness gate.

Oracle

The spar-dbc round-trip test is the oracle: the emitted AADL (ports, connections, bus binding) must parse → item-tree → scope → SystemInstance::instantiate with zero diagnostics. New test sample_dbc_emits_message_flows pins the EngineData (EngineECU → Gateway+System) and Status (Gateway → EngineECU) flows, the bus binding, and that the Vector__XXX Broadcast frame yields its data type but no flow ports.

Traceability

• REQ-INGEST-DBC-FLOWS-001 → implemented (description corrected to the faithful-modelling, not-NC-feeder scope).
• TEST-INGEST-DBC-FLOWS added in verification.yaml, satisfies the requirement.

🤖 Generated with Claude Code

[github-actions]

Rivet verification gate

✅ 20/20 passed

	count
Passed	20
Failed	0
Skipped (no steps)	0

Filter: (and (= type "feature") (or (has-tag "v093") (has-tag "v0100")))

Failed artifacts

(none)

_{Updated automatically by tools/post_verification_comment.py. Source of truth: artifacts/verification.yaml.}

[codecov]

Codecov Report

❌ Patch coverage is 97.36842% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
crates/spar-dbc/src/lib.rs	97.33%	2 Missing ⚠️

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