iterate-agent-harness — Failure → Durable Guard

When an agent run ends wrong, the fix is not just to redo the task — it is to change the harness so the whole class of failure cannot recur silently. This skill converts a single failure into a durable guard plus a regression check.

A failure you cannot reproduce, you cannot prove you fixed. Capture the failure mode, add a check that fails on it, then make the check pass with the smallest durable change.

Phase 0 — Capture the failure precisely