fix: use Optional[RunnableConfig] on all pipeline nodes to silence LangGraph warning (#776)

* fix: use Optional[RunnableConfig] on all pipeline nodes to silence LangGraph warning

LangGraph's RunnableCallable inspector only recognises RunnableConfig,
Optional[RunnableConfig], and their string equivalents as valid config
annotations. Four nodes (extract_alert, plan_actions, diagnose_root_cause,
publish_findings) were missing the config parameter entirely; the existing
resolve_integrations node used RunnableConfig | None (types.UnionType),
which also falls outside the accepted set.

Standardise all five node signatures to Optional[RunnableConfig] = None
and suppress ruff UP045 on those lines, since the stricter LangGraph
requirement takes precedence over the modern union-syntax preference.

Closes #773

* fix: use Optional[RunnableConfig] on all pipeline nodes to silence LangGraph warning

LangGraph's RunnableCallable inspector only accepts Optional[RunnableConfig]
(from typing) as a valid config annotation — not the Python 3.10+ union
syntax RunnableConfig | None. Using the union syntax causes a UserWarning
on every graph run. Suppressed ruff UP007/UP045/ARG001 since the LangGraph
interface contract takes precedence.

Closes #775

Author: udit-rawat

app/nodes/extract_alert/extract_node.py

@@ -3,8 +3,9 @@
 import json
 import logging
 import time
-from typing import Any
+from typing import Any, Optional
 
+from langchain_core.runnables import RunnableConfig
 from langsmith import traceable
 
 from app.nodes.extract_alert.extract import extract_alert_details
@@ -53,7 +54,7 @@ def _enrich_raw_alert(raw_alert: Any, details: AlertDetails) -> Any:
 
 
 @traceable(name="node_extract_alert")
-def node_extract_alert(state: InvestigationState) -> dict:
+def node_extract_alert(state: InvestigationState, config: Optional[RunnableConfig] = None) -> dict:  # noqa: ARG001,UP007,UP045
     """Classify and extract alert details from raw input (single LLM call)."""
     tracker = get_tracker()
     tracker.start("extract_alert", "Classifying and extracting alert details")

app/nodes/plan_actions/node.py

@@ -1,7 +1,8 @@
 """Plan actions node - planning only."""
 
-from typing import cast
+from typing import Optional, cast
 
+from langchain_core.runnables import RunnableConfig
 from langsmith import traceable
 from pydantic import BaseModel, Field
 
@@ -38,7 +39,7 @@ def get_retrieval_intent(self, action_name: str) -> RetrievalIntent | None:
 
 
 @traceable(name="node_plan_actions")
-def node_plan_actions(state: InvestigationState) -> dict:
+def node_plan_actions(state: InvestigationState, config: Optional[RunnableConfig] = None) -> dict:  # noqa: ARG001,UP007,UP045
     """Plan investigation actions and write plan outputs to state.
 
     Supports rerouting when new evidence changes the likely source family,

app/nodes/publish_findings/node.py

@@ -2,8 +2,9 @@
 
 import logging
 import os
-from typing import cast
+from typing import Optional, cast
 
+from langchain_core.runnables import RunnableConfig
 from langsmith import traceable
 
 from app.masking import MaskingContext
@@ -187,6 +188,9 @@ def generate_report(state: InvestigationState) -> dict:
 
 
 @traceable(name="node_publish_findings")
-def node_publish_findings(state: InvestigationState) -> dict:
+def node_publish_findings(
+    state: InvestigationState,
+    config: Optional[RunnableConfig] = None,  # noqa: ARG001,UP007,UP045
+) -> dict:
     """LangGraph node wrapper with LangSmith tracking."""
     return generate_report(state)

app/nodes/resolve_integrations/node.py

@@ -7,7 +7,7 @@
 
 import logging
 import os
-from typing import Any
+from typing import Any, Optional
 
 from langchain_core.runnables import RunnableConfig
 from langsmith import traceable
@@ -52,7 +52,8 @@ def _strip_bearer(token: str) -> str:
 
 @traceable(name="node_resolve_integrations")
 def node_resolve_integrations(
-    state: InvestigationState, config: RunnableConfig | None = None
+    state: InvestigationState,
+    config: Optional[RunnableConfig] = None,  # noqa: UP007,UP045
 ) -> dict:
     """Fetch all org integrations and classify them by service.
 

app/nodes/root_cause_diagnosis/node.py

@@ -1,7 +1,9 @@
 """Root cause diagnosis node - orchestration and entry point."""
 
 import os
+from typing import Optional
 
+from langchain_core.runnables import RunnableConfig
 from langsmith import traceable
 
 from app.investigation_constants import MAX_INVESTIGATION_LOOPS
@@ -199,6 +201,9 @@ def _handle_insufficient_evidence(state: InvestigationState, tracker) -> dict:
 
 
 @traceable(name="node_diagnose_root_cause")
-def node_diagnose_root_cause(state: InvestigationState) -> dict:
+def node_diagnose_root_cause(
+    state: InvestigationState,
+    config: Optional[RunnableConfig] = None,  # noqa: ARG001,UP007,UP045
+) -> dict:
     """LangGraph node wrapper with LangSmith tracking."""
     return diagnose_root_cause(state)