Dogfood run on t-578: dev agent returned success without creating the requested change, but loop auto-promoted status from in-progress to review. Promotion should require either explicit status update by agent or branch SHA change (new/amended commit).
Fixed in run_single_task: auto-promotion to review now requires a branch commit SHA change. If no commit change is produced, status remains open/in-progress and a comment is added instead of false promotion.