Haiku 4.5 occasionally wraps its JSON response in a markdown code
fence even with response_format={"type":"json_object"} enforced:
```json
{"clean": true, "reason": "polished read"}
```
Live testing the new reviewer caught this — every verdict was being
dropped as "reviewer returned non-JSON". Strip a single leading
trailing fence before json.loads. Defensive for any model that does
the same (Claude variants commonly fence JSON even when told not to).
Adds a unit test covering fenced output.
Giorgio Gilestro
385c5fdc60