# `Journey.Scheduler.Heartbeat`

Sends periodic heartbeat updates for a running computation.

Runs as a linked sibling to the worker process. Uses `trap_exit` to receive
EXIT messages when the worker exits (normal or crash), allowing immediate
cleanup without waiting for the next heartbeat interval.

Exit conditions:
- Worker exits → receives {:EXIT, pid, reason} → exits immediately
- Worker crashes → heartbeat process receives EXIT, worker is already dead
- Heartbeat process crashes → worker receives exit signal and dies (not trapping)
- Computation state changes → `update_heartbeat` returns 0 rows → checks state
- Deadline exceeded → marks as abandoned, exits non-normally to kill worker

# `run`

Runs the heartbeat loop for a computation.

Spawned as a linked sibling to the worker - exits when:
- Worker exits (link causes termination)
- Computation state changes (update_heartbeat returns 0 rows)

## Arguments
  - computation_id: The ID of the computation to heartbeat
  - interval_seconds: How often to send heartbeats
  - timeout_seconds: The heartbeat timeout (used to calculate new deadline)

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*Consult [api-reference.md](api-reference.md) for complete listing*