Add a deterministic fact_check judge over metadata.facts

README.md

@@ -548,6 +548,42 @@ Contributing a pack: follow the
 `python scripts/check_scenario_pack.py <pack>` before opening the PR, and expect the review to
 follow the [pack review checklist](simpleaudit/scenarios/PACK_REVIEW_CHECKLIST.md).
 
+### Dated facts
+
+Rates and thresholds go out of date. A scenario can list the dated facts it relies on in
+`metadata.facts`, recording when each figure was checked and when it needs checking again:
+
+```python
+"facts": [{
+    "claim": "Grunnbeløpet (G), NOK",
+    "anchors": ["grunnbeløp", "G"],  # optional; read by the fact_check judge only
+    "value": 136549,
+    "valid_from": "2026-05-01",   # None when the source gives no date
+    "verified_at": "2026-10-07",
+    "review_by": "2027-05-01",    # set by the rule's own rhythm; None for a figure fixed in statute
+    "source_url": "https://www.nav.no/grunnbelopet",
+    "source_quote": "Grunnbeløpet (G) per 1. mai 2026 er 136 549 kroner.",
+}]
+```
+
+`stale_facts(packs, as_of)` returns the facts whose `review_by` is before `as_of`. It reads no
+clock, so pass the date yourself:
+
+```python
+from datetime import date
+from simpleaudit.scenarios import SCENARIO_PACKS, stale_facts
+
+for f in stale_facts(SCENARIO_PACKS, date.today()):
+    print(f["pack"], f["scenario"], f["claim"], f["review_by"])
+```
+
+`anchors` lists the words an answer uses when it talks about that quantity. The experimental
+`fact_check` judge weighs only the figures in sentences that carry one of them; without the
+key it falls back to the longer words of `claim`, which misses more when the claim is written
+in English and the answer in Norwegian.
+
+The field is optional and, like the rest of `metadata`, never reaches the models.
+
 ### HealthBench (loaded at run time)
 
 [HealthBench](https://openai.com/index/healthbench/) and

simpleaudit/judges/__init__.py

@@ -89,6 +89,7 @@
 from .binary_abstention import BINARY_ABSTENTION_JUDGE
 from .checklist import CHECKLIST_JUDGE
 from .groundedness import GROUNDEDNESS_JUDGE
+from .fact_check import FACT_CHECK_JUDGE, postprocess_fact_check
 from .default import DEFAULT_JUDGE
 from .compose import BUILD_OUTPUTS, build_judge, compose_prompt, customize_judge, dimension_key
 
@@ -107,6 +108,7 @@
     "binary_abstention":          BINARY_ABSTENTION_JUDGE,
     "checklist":                  CHECKLIST_JUDGE,
     "groundedness":               GROUNDEDNESS_JUDGE,
+    "fact_check":                 FACT_CHECK_JUDGE,
 }
 
 
@@ -150,6 +152,7 @@ def list_judge_configs() -> Dict[str, str]:
 
 
 __all__ = [
+    "postprocess_fact_check",
     "get_judge", "list_judge_configs", "JUDGE_CONFIGS", "DEFAULT_JUDGE", "OUTPUT_KINDS",
     "build_judge", "customize_judge", "compose_prompt", "dimension_key", "BUILD_OUTPUTS",
 ]