Event types¶

Every event carries id, type, timestamp and metadata. The metadata keys below are in addition to the run-level metadata (run_id, backfill_id, anything the caller passed) that every event inherits.

Run¶

Emitted by the runner's RunState.

Type	When	Metadata
`run_started`	The walk begins.	`partition_or_window`, `message`
`run_completed`	Every operation completed or was skipped.	`partition_or_window`, `message`
`run_failed`	At least one operation failed, or the walk itself broke.	`partition_or_window`, `error` (walk failures only), `message`

Operation¶

Emitted by the runner's RunState with a deterministic id derived from run id, component id and type. Common metadata: component_id, component_kind, component_key, source_id, partition_or_window, message.

Type	When
`operation_queued`	At run start, for every materializable operation.
`operation_started`	The operation was submitted.
`operation_completed`	`execute()` returned.
`operation_failed`	`execute()` raised. Adds `error` and, when the operation captures tracebacks, `traceback`.
`operation_canceled`	An upstream operation failed, or the run ended early (fail-fast break, machinery abort) before the operation was submitted.

Asset data¶

Emitted by Asset.run_async() around data(). Metadata: component_id, component_kind, component_key, qualified_key, source_id, partition_or_window, message.

Type	When
`asset_data_started`	Before `data()`.
`asset_data_completed`	After `data()` returned.
`asset_data_failed`	`data()` raised. Adds `error`, `traceback`.

Destination I/O¶

Emitted around each read() and write(). Metadata as for asset data, plus destination_key.

Type	When
`dest_read_started`, `dest_read_completed`, `dest_read_failed`	Reading an upstream dependency. Failures add `error`, `traceback`.
`dest_write_started`, `dest_write_completed`, `dest_write_failed`	Writing the asset's result. Failures add `error`, `traceback`.

User logging¶

Type	When	Metadata
`log`	`context.logger.<level>(message)`, or an `EventLogger`. Also used by the framework for the empty-result warning.	`component_id`, `component_kind`, `component_key`, `source_id`, `level` (`DEBUG`, `INFO`, `WARNING`, `ERROR`), `message`

Emitted by the platform¶

Defined in the core so every consumer shares one vocabulary; produced by the scheduler, not by the core runners.

Type	Meaning
`backfill_started`, `backfill_completed`, `backfill_failed`	Lifecycle of a multi-partition backfill.
`hook_fired`, `hook_failed`	A hook's `fire()` ran, or raised.

Console rendering levels¶

ConsoleEventHandler maps types to logging levels: failures at ERROR, operation_canceled at WARNING, operation_queued and all asset-data and destination I/O events at DEBUG, everything else at INFO. log events use their own level.

Serialization¶

Event.to_dict() flattens to {"event_id", "type", "timestamp", **metadata}; to_json() encodes it. Event.from_dict() and from_json() parse it back, generating a new id only when event_id is absent. Event.from_log_line() accepts an @EVENT:{...} line or a bare JSON object and returns None for anything else. Invalid input raises EventError.