feat: compare accountability update deltas

tests/test_accountability_root_adapters.py

@@ -5,6 +5,7 @@ from railiance_fabric.accountability_roots import (
     AccountabilityEvidenceStore,
     build_identity_projection,
     build_ownership_review,
+    build_update_delta,
     collect_accountability_root_evidence,
     load_accountability_root_manifest,
 )
@@ -191,6 +192,78 @@ def test_review_identity_cli_persists_decision_for_ownership_review(tmp_path: Pa
     assert repo_item["decision"]["reviewer"] == "tester"
 
 
+def test_update_delta_detects_ownership_changes_and_unchanged_runs(tmp_path: Path) -> None:
+    manifest_path = _fixture_manifest(tmp_path)
+    manifest = load_accountability_root_manifest(manifest_path)
+    projection = build_identity_projection(collect_accountability_root_evidence(manifest_path), manifest)
+    review = build_ownership_review(projection, manifest)
+
+    unchanged = build_update_delta(
+        projection,
+        review,
+        previous_identity_projection=projection,
+        previous_ownership_review=review,
+    )
+    validator = draft202012_validator(Path("schemas/accountability-update-delta.schema.yaml"))
+    assert list(validator.iter_errors(unchanged)) == []
+    assert unchanged["summary"]["promotion_needed"] is False
+    assert unchanged["node_delta"]["unchanged"]
+
+    store = AccountabilityEvidenceStore(tmp_path / "evidence.sqlite3")
+    store.add_review_decision(
+        stable_key="identity:repository:fixture-repo",
+        decision="accept",
+        reviewer="tester",
+        owner_actor_id="actor.fixture.lord",
+        fabric_id="fabric.fixture.primary",
+    )
+    accepted_review = build_ownership_review(
+        projection,
+        manifest,
+        review_decisions=store.latest_review_decisions(),
+    )
+    changed = build_update_delta(
+        projection,
+        accepted_review,
+        previous_identity_projection=projection,
+        previous_ownership_review=review,
+    )
+    assert changed["summary"]["promotion_needed"] is True
+    assert "identity:repository:fixture-repo" in changed["change_sets"]["ownership"]
+    assert "identity:repository:fixture-repo" in changed["change_sets"]["review_state"]
+
+
+def test_discover_roots_cli_can_emit_delta(tmp_path: Path, capsys) -> None:
+    manifest = _fixture_manifest(tmp_path)
+    manifest_data = load_accountability_root_manifest(manifest)
+    projection = build_identity_projection(collect_accountability_root_evidence(manifest), manifest_data)
+    review = build_ownership_review(projection, manifest_data)
+    projection_path = tmp_path / "previous-identities.json"
+    review_path = tmp_path / "previous-ownership.json"
+    projection_path.write_text(json.dumps(projection), encoding="utf-8")
+    review_path.write_text(json.dumps(review), encoding="utf-8")
+
+    assert (
+        cli_main(
+            [
+                "discover-roots",
+                "--manifest",
+                str(manifest),
+                "--delta",
+                "--previous-identity-projection",
+                str(projection_path),
+                "--previous-ownership-review",
+                str(review_path),
+            ]
+        )
+        == 0
+    )
+
+    payload = json.loads(capsys.readouterr().out)
+    assert payload["kind"] == "AccountabilityUpdateDelta"
+    assert payload["summary"]["promotion_needed"] is False
+
+
 def _fixture_manifest(tmp_path: Path) -> Path:
     workspace = tmp_path / "workspace"
     repo = workspace / "fixture-repo"