Create and trigger an asset sensor in Dagster to launch a downstream job when an upstream asset materializes

Steps

1. Decorate a function with @asset_sensor(asset_key=AssetKey([...]), job=downstream_job) to create a sensor that monitors a specific asset for new materialization events
2. Inside the sensor function, receive the AssetMaterializationEvent and return RunRequest() to trigger the downstream job; return SkipReason('...') if no action is needed for this materialization
3. Include the sensor in your Definitions object alongside the monitored asset and the downstream job so Dagster can resolve all references at load time
4. Start the sensor from the Dagster UI or via CLI (dagster sensor start --name my_sensor) so the Dagster daemon begins polling for new materialization events
5. For multi-asset monitoring, use the @multi_asset_sensor decorator, which accumulates events across multiple asset keys and allows you to emit one RunRequest covering all new materializations since the last cursor advance