Finish Knative reef admission workplan

tests/test_admission_freshness.py

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+import datetime as dt
+import importlib.util
+from pathlib import Path
+
+MODULE = Path(__file__).parents[1] / "tools/check_admission_freshness.py"
+spec = importlib.util.spec_from_file_location("freshness", MODULE)
+freshness = importlib.util.module_from_spec(spec)
+spec.loader.exec_module(freshness)
+
+
+def record(state="verified", status="pass", risk="open"):
+    return {
+        "checked_at": "2026-07-26T18:00:00Z",
+        "readiness_state": state,
+        "checks": {"compatibility": {"status": status}},
+        "residual_risks": [{"risk": "single node", "status": risk}],
+    }
+
+
+def test_verified_may_retain_explicit_open_risk():
+    now = dt.datetime(2026, 7, 26, 19, tzinfo=dt.timezone.utc)
+    assert freshness.assess(record(), now, 24) == []
+
+
+def test_production_approval_fails_closed():
+    now = dt.datetime(2026, 7, 26, 19, tzinfo=dt.timezone.utc)
+    failures = freshness.assess(record("production-approved", "unknown"), now, 24)
+    assert len(failures) == 2
+
+
+def test_stale_evidence_fails():
+    now = dt.datetime(2026, 7, 28, 19, tzinfo=dt.timezone.utc)
+    assert "evidence is stale" in freshness.assess(record(), now, 24)