When triggering a CircleCI pipeline via the API, the call is fire-and-forget — there's no way for the caller to know when the pipeline has finished without polling.

What we're asking for: An optional callback_url field on the trigger pipeline API. When provided, CircleCI would POST a lightweight completion notification to that URL when the pipeline finishes — without requiring any pre-configuration or config changes.

This would be particularly useful for:

Cloud-hosted orchestration services and agents that trigger pipelines and need to continue downstream work on completion

Any system that currently has to poll the CircleCI status API in a loop to detect when a triggered pipeline is done.

This feature request is for a minimal payload — pipeline ID and terminal status. Please feel free to share any additional payload requests in the comments.

Current workaround: Poll the pipeline/workflow status API repeatedly until a terminal state is returned. This is wasteful, adds latency, and doesn't scale for long-running pipelines.