diff --git a/backend/openmlr/db/operations.py b/backend/openmlr/db/operations.py
index 2ea72a1..7bafae0 100644
--- a/backend/openmlr/db/operations.py
+++ b/backend/openmlr/db/operations.py
@@ -385,7 +385,7 @@ async def upsert_paper_resource(
 async def upsert_resource(
     db: AsyncSession, conv_id: int,
     resource_id: str, title: str, resource_type: str,
-    content: str = None, url: str = None,
+    content: str | None = None, url: str | None = None,
 ) -> ConversationResource:
     """Create or update a resource by resource_id."""
     existing = await get_resource_by_id(db, resource_id)
@@ -478,7 +478,7 @@ async def update_job_status(
 
 # ---- User Settings ----
 
-async def get_user_settings(db: AsyncSession, user_id: int, category: str = None) -> dict:
+async def get_user_settings(db: AsyncSession, user_id: int, category: str | None = None) -> dict:
     """Get user settings as a dict. Optionally filter by category."""
     query = select(UserSetting).where(UserSetting.user_id == user_id)
     if category:
diff --git a/backend/openmlr/services/session_manager.py b/backend/openmlr/services/session_manager.py
index d59d7b1..825d779 100644
--- a/backend/openmlr/services/session_manager.py
+++ b/backend/openmlr/services/session_manager.py
@@ -86,11 +86,13 @@ async def get_or_create_session(
 
         session = Session(config=config, conversation_id=conversation_id)
 
+        # Import here (not at module level) to avoid circular imports
+        from ..db import operations as ops
+
         # Determine effective compute node
         effective_node = None
         if user_id and db:
             try:
-                from ..db import operations as ops
                 # Check conversation override
                 conv = await ops.get_conversation_by_id(db, conversation_id)
                 if conv and conv.extra:
@@ -130,7 +132,6 @@ async def get_or_create_session(
         # Load MCP servers from user settings if available
         if user_id and db:
             try:
-                from ..db import operations as ops
                 user_settings = await ops.get_all_settings(db, user_id, category="mcp")
                 mcp_settings = user_settings.get("mcp", {})
                 mcp_servers = mcp_settings.get("servers", {})
diff --git a/backend/openmlr/tools/compute_tools.py b/backend/openmlr/tools/compute_tools.py
index 2d6c0c9..7ccc6b0 100644
--- a/backend/openmlr/tools/compute_tools.py
+++ b/backend/openmlr/tools/compute_tools.py
@@ -67,6 +67,7 @@ async def _handle_probe(node_name: str, user_id: int = None, db=None, **kwargs):
     from ..compute import WorkspaceManager
     from ..sandbox.manager import SandboxManager
 
+    sm = None
     try:
         wm = WorkspaceManager()
         sm = SandboxManager(workspace_manager=wm)
@@ -115,7 +116,8 @@ async def _handle_probe(node_name: str, user_id: int = None, db=None, **kwargs):
 
     except Exception as e:
         try:
-            await sm.destroy()
+            if sm is not None:
+                await sm.destroy()
         except Exception:
             pass
         await ops.update_compute_node(
diff --git a/backend/tests/test_agent_loop.py b/backend/tests/test_agent_loop.py
index dab8179..a430bf3 100644
--- a/backend/tests/test_agent_loop.py
+++ b/backend/tests/test_agent_loop.py
@@ -343,8 +343,6 @@ async def test_cancelled_returns_none(self, mock_session):
 
         async def mock_stream(messages, config, tools):
             yield "Hello"
-            if False:
-                yield
 
         with patch("openmlr.agent.loop.LLMProvider.generate_stream") as mock_str:
             mock_str.return_value = mock_stream(None, None, None)
diff --git a/qodana.yaml b/qodana.yaml
index 9a4826a..66eac95 100644
--- a/qodana.yaml
+++ b/qodana.yaml
@@ -4,7 +4,11 @@
 
 version: "1.0"
 linter: jetbrains/qodana-python-community:2025.3
+projectJDK: "python3.12"
 profile:
   name: qodana.recommended
+bootstrap: |
+  # Ensure Qodana uses Python 3.12+ for correct type hint inspection (PEP 604, PEP 585)
+  python3.12 --version 2>/dev/null || python3 --version
 include:
   - name: CheckDependencyLicenses