refactor(backend): consolidate thread_id resolution into shared get_thread_id() utility (#2522)

Extract duplicated thread_id fallback logic from 11 files into a single
  deerflow.utils.runtime.get_thread_id() function with a documented 3-level
  cascade (runtime.context → runtime.config → get_config()).

  The module docstring also clarifies the __pregel_runtime injection pattern used in
  gateway mode.

backend/packages/harness/deerflow/agents/middlewares/loop_detection_middleware.py

@@ -25,6 +25,8 @@ from langchain.agents.middleware import AgentMiddleware
 from langchain_core.messages import HumanMessage
 from langgraph.runtime import Runtime
 
+from deerflow.utils.runtime import get_thread_id
+
 logger = logging.getLogger(__name__)
 
 # Defaults — can be overridden via constructor
@@ -183,10 +185,7 @@ class LoopDetectionMiddleware(AgentMiddleware[AgentState]):
 
     def _get_thread_id(self, runtime: Runtime) -> str:
         """Extract thread_id from runtime context for per-thread tracking."""
-        thread_id = runtime.context.get("thread_id") if runtime.context else None
-        if thread_id:
-            return thread_id
-        return "default"
+        return get_thread_id(runtime) or "default"
 
     def _evict_if_needed(self) -> None:
         """Evict least recently used threads if over the limit.

backend/packages/harness/deerflow/agents/middlewares/memory_middleware.py

@@ -5,12 +5,12 @@ from typing import override
 
 from langchain.agents import AgentState
 from langchain.agents.middleware import AgentMiddleware
-from langgraph.config import get_config
 from langgraph.runtime import Runtime
 
 from deerflow.agents.memory.message_processing import detect_correction, detect_reinforcement, filter_messages_for_memory
 from deerflow.agents.memory.queue import get_memory_queue
 from deerflow.config.memory_config import get_memory_config
+from deerflow.utils.runtime import get_thread_id
 
 logger = logging.getLogger(__name__)
 
@@ -57,11 +57,8 @@ class MemoryMiddleware(AgentMiddleware[MemoryMiddlewareState]):
         if not config.enabled:
             return None
 
-        # Get thread ID from runtime context first, then fall back to LangGraph's configurable metadata
-        thread_id = runtime.context.get("thread_id") if runtime.context else None
-        if thread_id is None:
-            config_data = get_config()
-            thread_id = config_data.get("configurable", {}).get("thread_id")
+        # Get thread ID from runtime context
+        thread_id = get_thread_id(runtime)
         if not thread_id:
             logger.debug("No thread_id in context, skipping memory update")
             return None

backend/packages/harness/deerflow/agents/middlewares/sandbox_audit_middleware.py

@@ -14,6 +14,7 @@ from langgraph.prebuilt.tool_node import ToolCallRequest
 from langgraph.types import Command
 
 from deerflow.agents.thread_state import ThreadState
+from deerflow.utils.runtime import get_thread_id
 
 logger = logging.getLogger(__name__)
 
@@ -218,15 +219,7 @@ class SandboxAuditMiddleware(AgentMiddleware[ThreadState]):
     # ------------------------------------------------------------------
 
     def _get_thread_id(self, request: ToolCallRequest) -> str | None:
-        runtime = request.runtime  # ToolRuntime; may be None-like in tests
-        if runtime is None:
-            return None
-        ctx = getattr(runtime, "context", None) or {}
-        thread_id = ctx.get("thread_id") if isinstance(ctx, dict) else None
-        if thread_id is None:
-            cfg = getattr(runtime, "config", None) or {}
-            thread_id = cfg.get("configurable", {}).get("thread_id")
-        return thread_id
+        return get_thread_id(request.runtime)
 
     _AUDIT_COMMAND_LIMIT = 200
 

backend/packages/harness/deerflow/agents/middlewares/summarization_middleware.py

@@ -14,6 +14,8 @@ from langgraph.config import get_config
 from langgraph.graph.message import REMOVE_ALL_MESSAGES
 from langgraph.runtime import Runtime
 
+from deerflow.utils.runtime import get_thread_id
+
 logger = logging.getLogger(__name__)
 
 
@@ -35,18 +37,6 @@ class BeforeSummarizationHook(Protocol):
     def __call__(self, event: SummarizationEvent) -> None: ...
 
 
-def _resolve_thread_id(runtime: Runtime) -> str | None:
-    """Resolve the current thread ID from runtime context or LangGraph config."""
-    thread_id = runtime.context.get("thread_id") if runtime.context else None
-    if thread_id is None:
-        try:
-            config_data = get_config()
-        except RuntimeError:
-            return None
-        thread_id = config_data.get("configurable", {}).get("thread_id")
-    return thread_id
-
-
 def _resolve_agent_name(runtime: Runtime) -> str | None:
     """Resolve the current agent name from runtime context or LangGraph config."""
     agent_name = runtime.context.get("agent_name") if runtime.context else None
@@ -334,7 +324,7 @@ class DeerFlowSummarizationMiddleware(SummarizationMiddleware):
         event = SummarizationEvent(
             messages_to_summarize=tuple(messages_to_summarize),
             preserved_messages=tuple(preserved_messages),
-            thread_id=_resolve_thread_id(runtime),
+            thread_id=get_thread_id(runtime),
             agent_name=_resolve_agent_name(runtime),
             runtime=runtime,
         )

backend/packages/harness/deerflow/agents/middlewares/thread_data_middleware.py

@@ -3,11 +3,11 @@ from typing import NotRequired, override
 
 from langchain.agents import AgentState
 from langchain.agents.middleware import AgentMiddleware
-from langgraph.config import get_config
 from langgraph.runtime import Runtime
 
 from deerflow.agents.thread_state import ThreadDataState
 from deerflow.config.paths import Paths, get_paths
+from deerflow.utils.runtime import get_thread_id
 
 logger = logging.getLogger(__name__)
 
@@ -75,11 +75,7 @@ class ThreadDataMiddleware(AgentMiddleware[ThreadDataMiddlewareState]):
 
     @override
     def before_agent(self, state: ThreadDataMiddlewareState, runtime: Runtime) -> dict | None:
-        context = runtime.context or {}
-        thread_id = context.get("thread_id")
-        if thread_id is None:
-            config = get_config()
-            thread_id = config.get("configurable", {}).get("thread_id")
+        thread_id = get_thread_id(runtime)
 
         if thread_id is None:
             raise ValueError("Thread ID is required in runtime context or config.configurable")

backend/packages/harness/deerflow/agents/middlewares/uploads_middleware.py

@@ -11,6 +11,7 @@ from langgraph.runtime import Runtime
 
 from deerflow.config.paths import Paths, get_paths
 from deerflow.utils.file_conversion import extract_outline
+from deerflow.utils.runtime import get_thread_id
 
 logger = logging.getLogger(__name__)
 
@@ -213,14 +214,7 @@ class UploadsMiddleware(AgentMiddleware[UploadsMiddlewareState]):
             return None
 
         # Resolve uploads directory for existence checks
-        thread_id = (runtime.context or {}).get("thread_id")
-        if thread_id is None:
-            try:
-                from langgraph.config import get_config
-
-                thread_id = get_config().get("configurable", {}).get("thread_id")
-            except RuntimeError:
-                pass  # get_config() raises outside a runnable context (e.g. unit tests)
+        thread_id = get_thread_id(runtime)
         uploads_dir = self._paths.sandbox_uploads_dir(thread_id) if thread_id else None
 
         # Get newly uploaded files from the current message's additional_kwargs.files