test: cover user-owned session security boundaries

harness/tests/test_session_repository.py

@@ -5,7 +5,7 @@ import pytest
 from tht.config import DatabaseConfig, load_config
 from tht.decisions import DecisionInput
 from tht.session.filesystem_repository import FilesystemSessionRepository
-from tht.session.models import PrincipalContext, SessionManifest
+from tht.session.models import PrincipalContext, SessionManifest, local_principal
 from tht.session.repository import build_session_repository, resolve_principal
 from tht.session.store import SessionError
 from tht.session.store import create_session
@@ -105,6 +105,25 @@ def test_filesystem_repository_keeps_preferences_per_principal(tmp_path):
     assert bob.get_preferences() == {}
 
 
+def test_two_local_homes_have_independent_identities_sessions_and_preferences(tmp_path):
+    alice_home = tmp_path / "alice-home"
+    bob_home = tmp_path / "bob-home"
+    alice = FilesystemSessionRepository(alice_home, "demo", local_principal(alice_home))
+    bob = FilesystemSessionRepository(bob_home, "demo", local_principal(bob_home))
+    session_id = str(uuid.uuid4())
+
+    alice.create(_manifest(session_id))
+    alice.set_preferences({"model": "glm"})
+
+    assert alice.principal.subject != bob.principal.subject
+    assert (alice.root / session_id / "session_manifest.yaml").exists()
+    assert not (bob.root / session_id).exists()
+    assert bob.list() == []
+    assert bob.get_preferences() == {}
+    with pytest.raises(SessionError, match="Sessione non trovata"):
+        bob.get(session_id)
+
+
 @pytest.mark.parametrize("session_id", ["2026-01-01-000000-test", "2026-01-01-000000-x", "s1"])
 def test_filesystem_repository_reads_safe_legacy_session_ids(tmp_path, session_id):
     repository = FilesystemSessionRepository(