test: hard-fail the suite when the tenant resolves to production

Session-scoped autouse guard in tests/conftest.py refuses to run any
test (pytest.exit, returncode 1) when the effective tenant resolves
to the production tenant jpmschweitzer - the same guard library-desk
applies on its side. _initialize_app now depends on the guard so the
refusal happens before any initialization.

Suite-level assertions pin that the live session runs under the
llm_tester namespaces: Qdrant memories_llm_tester collection and
Redis session:llm_tester:* keys. The biographer/memory unit tests
already run fully mocked (no shared-service writes); the e2e
isolation tests already used llm_tester - their constants now derive
from the shared TEST_TENANT/PRODUCTION_TENANT config constants so a
drift fails loudly instead of silently splitting.

Verified: ENVIRONMENT=production pytest run exits 1 with the TENANT
GUARD message and zero tests executed.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/conftest.py

@@ -12,11 +12,51 @@ from src.main import app
 
 
 @pytest.fixture(scope="session", autouse=True)
-def _initialize_app():
+def _tenant_guard():
+    """
+    Hard-fail the whole suite if the effective tenant resolves to the
+    production tenant ("jpmschweitzer").
+
+    Isolation is tenant-based: tests that touch shared services
+    (Qdrant memories collections, Wiki.js via library-desk, Neo4j,
+    Redis) must run under the reserved test tenant "llm_tester" (or a
+    test_-prefixed namespace). This mirrors the guard library-desk
+    applies on its side.
+    """
+    from src.core.config import PRODUCTION_TENANT, config
+    from src.core.context import get_default_user
+    from src.core.multi_tenancy import get_memory_collection_name
+
+    effective = get_default_user()
+    if (
+        effective == PRODUCTION_TENANT
+        or config.effective_default_user == PRODUCTION_TENANT
+    ):
+        pytest.exit(
+            f"TENANT GUARD: refusing to run the test suite - the effective "
+            f"tenant resolves to the production tenant '{PRODUCTION_TENANT}' "
+            f"(ENVIRONMENT={config.ENVIRONMENT.value}, "
+            f"DEFAULT_USER={config.DEFAULT_USER}). Tests must run under "
+            f"'llm_tester' or a test_-prefixed tenant.",
+            returncode=1,
+        )
+
+    # The Qdrant memories namespace derived from the effective tenant
+    # must never be the production collection.
+    assert get_memory_collection_name(effective) != get_memory_collection_name(
+        PRODUCTION_TENANT
+    ), "test suite would target the production memories collection"
+
+
+@pytest.fixture(scope="session", autouse=True)
+def _initialize_app(_tenant_guard):
     """
     Run application lifespan (Claude health check, household registration, etc.)
     once per test session. ASGITransport doesn't trigger lifespan events,
     so we call it explicitly.
+
+    Depends on _tenant_guard so the suite refuses to start under the
+    production tenant before any initialization happens.
     """
     from src.core.startup import initialize_application
     asyncio.run(initialize_application())