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name: core-services-and-runtime description: "Guides cereal/msgq messaging, Params, manager processes, loggerd, service timing, and runtime service diagnostics in openpilot." disable-model-invocation: true metadata: disco-role: operating license: MIT

core-services-and-runtime

Use this sub-skill for openpilot's runtime internals: cereal messaging, msgq pub/sub, Params, managed_processes, loggerd/uploader/deleter, hardware paths, service timing, and CPU-safe runtime diagnostics.

Read first

• references/messaging-and-params.md for message/Params APIs and native-extension prerequisites.
• references/service-runtime.md for manager, loggerd, service timing, and filesystem path behavior.
• references/troubleshooting.md for msgq/Params/native-extension/service failures.

Bundled helpers

• scripts/check_service_names.py: print service names, frequencies, and decimation information from SERVICE_LIST.
• scripts/params_key_probe.py: inspect known Params keys and default/type guidance without writing values.

Workflow

1. Confirm the native extension state first. If msgq.ipc_pyx or libparams_c.so is missing, fix the build before deeper analysis.
2. Use cereal.messaging tests or helper scripts to understand socket/update semantics.
3. Treat Params writes as state-mutating; prefer read-only probes and clear warnings.
4. For loggerd/uploader/deleter or service timing, choose small focused tests and temporary directories.
5. For camera/encoder or full onroad tests, check whether hardware prerequisites are present; if not, document the skip instead of claiming failure.

Boundaries

• Route route/log parsing questions to route-log-analysis.
• Route car-interface and control behavior to car-ports-and-controls.
• Route replay/simulator/GUI tools to simulator-and-visual-tools.