Finish KG-WP-0003: stream completeness and live qonto observation

Classify evidence as load-bearing or attributive, draft the emission-cadence
declaration for Taxonomy, treat silence as a stream finding, keep completeness
separate from record richness, forbid immune memory as a state plane, and make
containment proposals reconstructable to their origin. Observe real
qonto-assistant audit events; deny-class completeness stays unknown until the
source publishes a heartbeat.

Assistant: grok
Assistant-Session: 01a05ef1-9e5a-70f2-b0ff-0b05d6b38ae9

tests/test_evidence_class.py

@@ -0,0 +1,91 @@
+import pytest
+
+from kings_guard.adapters import observation_from_audit_event
+from kings_guard.contracts import DeclaredEvidenceSource, EvidenceClass
+
+from helpers import load_pilot, observation_from_fixture
+
+
+def test_genome_declares_both_evidence_classes() -> None:
+    genome = load_pilot().genome
+    classes = {source.event_class: source.evidence_class for source in genome.evidence_sources}
+
+    assert classes["audit.deny"] is EvidenceClass.LOAD_BEARING
+    assert classes["audit.allow"] is EvidenceClass.ATTRIBUTIVE
+    assert classes["audit.heartbeat"] is EvidenceClass.LOAD_BEARING
+
+
+def test_observation_copies_declared_class_and_does_not_infer_it() -> None:
+    fixture = load_pilot()
+    observation = observation_from_fixture(fixture)
+
+    declared = fixture.genome.source_for("audit.deny")
+    assert declared is not None
+    assert observation.evidence_class is declared.evidence_class
+    assert observation.evidence_class is EvidenceClass.LOAD_BEARING
+    joined = " ".join(fixture.evidence_class_reasoning)
+    assert "source declares" in joined
+    assert "does not infer" in joined
+    assert all(source.reasoning for source in fixture.genome.evidence_sources)
+
+
+def test_allow_event_is_attributive_because_the_source_said_so() -> None:
+    fixture = load_pilot()
+    event = dict(fixture.audit_event)
+    event["decision"] = "allow"
+    event["deny_reason"] = None
+    event["request_id"] = "req-allow"
+
+    observation = observation_from_audit_event(
+        event,
+        subject_id=fixture.normalization_hints["subject_id"],
+        capability_scope=fixture.normalization_hints["capability_scope"],
+        identity_binding=fixture.normalization_hints["identity_binding"],
+        egress_destination=fixture.normalization_hints["egress_destination"],
+        genome=fixture.genome,
+    )
+
+    assert observation.event_class == "audit.allow"
+    assert observation.evidence_class is EvidenceClass.ATTRIBUTIVE
+
+
+def test_class_mismatch_with_source_declaration_is_rejected() -> None:
+    fixture = load_pilot()
+    with pytest.raises(ValueError, match="does not match source declaration"):
+        observation_from_audit_event(
+            fixture.audit_event,
+            subject_id=fixture.normalization_hints["subject_id"],
+            capability_scope=fixture.normalization_hints["capability_scope"],
+            identity_binding=fixture.normalization_hints["identity_binding"],
+            egress_destination=fixture.normalization_hints["egress_destination"],
+            genome=fixture.genome,
+            evidence_class=EvidenceClass.ATTRIBUTIVE,
+        )
+
+
+def test_class_cannot_be_inferred_from_event_contents() -> None:
+    fixture = load_pilot()
+    with pytest.raises(ValueError, match="does not infer"):
+        observation_from_audit_event(
+            fixture.audit_event,
+            subject_id=fixture.normalization_hints["subject_id"],
+            capability_scope=fixture.normalization_hints["capability_scope"],
+            identity_binding=fixture.normalization_hints["identity_binding"],
+            egress_destination=fixture.normalization_hints["egress_destination"],
+        )
+
+
+def test_declared_source_is_expressible_on_genome_and_observation() -> None:
+    source = DeclaredEvidenceSource(
+        source_id="example.audit.deny",
+        source_system="example",
+        event_class="audit.deny",
+        evidence_class=EvidenceClass.LOAD_BEARING,
+        reasoning="denials are load-bearing by statute §9.6",
+        cadence_form="heartbeat-or-reconciliation",
+    )
+    assert source.evidence_class is EvidenceClass.LOAD_BEARING
+    assert observation_from_fixture().evidence_class in {
+        EvidenceClass.LOAD_BEARING,
+        EvidenceClass.ATTRIBUTIVE,
+    }