Cancel a run

Requests cancellation. Cancellation is cooperative, not immediate.

• A run that has not started yet stops at once, state CANCELLED.
• A running run keeps going to its next round boundary, then stops. Expect it to keep reporting a running and still-advancing state for 5–15 minutes, sometimes ~20.
• Cancelling during the early setup phases takes longer still, since the request is not observed until the first round check.
• A finished run returns 409.

Round wall-clock is dominated by fixed overhead, not by the size of your data, so a small dataset does not cancel any faster.

Never assume the run has stopped. Poll GET /{featureRefinementKey}/progress until the state is terminal. A CANCELLED entry appears on recentActivities as soon as the request is accepted, which is observable before the top-level state flips.