[bburda]

Pull Request

Summary

The SSE fault handler reads fault events from FaultEventSource, a ROS-free interface built on the shared fault types from #736. The ROS side implements it with a subscription to the fault event topic. Fault JSON keeps 64-bit seconds.

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Issue

• part of Build the gateway HTTP layer into gateway_core #737

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Type

• Bug fix
• New feature or tests
• Breaking change
• Documentation only

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Testing

• ./scripts/test.sh test_sse_fault_handler
• ./scripts/test.sh integ --packages-select ros2_medkit_integration_tests covers the fault stream end to end (test_sse_fault_stream, test_aggregator_fault_stream, test_scenario_fault_lifecycle).

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Checklist

• Breaking changes are clearly described (and announced in docs / changelog if needed)
• Tests were added or updated if needed
• Docs were updated if behavior or public API changed

[mfaferek93]

subscribe() replaces the single callback and unsubscribe() clears it for everyone. A second SSEFaultHandler on the same services takes the stream from the first one, and when either is destroyed the other stops getting events. Before this PR each handler had its own subscription. The test fixture already hits this: GatewayNode's own handler, then handler_, then limited_handler/fast_handler. Have subscribe() return an owned handle that removes only its own callback, and add a test where two handlers both receive an event and one survives the other's destruction.