feat(harness): add local session repository

harness/tests/test_local_identity.py

@@ -0,0 +1,17 @@
+import json
+import uuid
+
+from tht.session.models import local_principal
+
+
+def test_local_identity_uuid_is_stable_across_restarts(tmp_path):
+    first = local_principal(tmp_path)
+    restarted = local_principal(tmp_path)
+
+    assert first == restarted
+    assert first.issuer == "local"
+    assert uuid.UUID(first.subject, version=4).version == 4
+    assert json.loads((tmp_path / "identity.json").read_text()) == {
+        "issuer": "local",
+        "subject": first.subject,
+    }