Workflow-mode runtime hardening (needs live repro)

Static review found the /workflow draft-confirm-run-monitor-cancel shape sound but could not verify runtime behavior. Needed: live repro of any stall, orphaned child, stale count, or cancel failure, then trace and fix. Reporter path: drive /workflow until it misbehaves and paste the symptom with the run id.

Start by driving the /workflow path through draft, confirm, run, monitor, and cancel until a stall, orphaned child, stale count, or cancel failure appears. Record the symptom and run id, then trace the runtime behavior and verify the failure is fixed with a repeatable live repro.

Written by the indexing model from the issue text.