fix(gateway): prevent 400 error when client sends context with configurable (#1660)

* fix(gateway): prevent 400 error when client sends context with configurable

Fixes #1290

LangGraph >= 0.6.0 rejects requests that include both 'configurable' and
'context' in the run config. If the client (e.g. useStream hook) sends
a 'context' key, we now honour it and skip creating our own
'configurable' dict to avoid the conflict.

When no 'context' is provided, we fall back to the existing
'configurable' behaviour with thread_id.

* fix(gateway): address review feedback — warn on dual keys, fix runtime injection, add tests

- Log a warning when client sends both 'context' and 'configurable' so
  it's no longer silently dropped (reviewer feedback)
- Ensure thread_id is available in config['context'] when present so
  middlewares can find it there too
- Add test coverage for the context path, the both-keys-present case,
  passthrough of other keys, and the no-config fallback

* style: ruff format services.py

---------

Co-authored-by: JasonOA888 <JasonOA888@users.noreply.github.com>
Co-authored-by: Willem Jiang <willem.jiang@gmail.com>

backend/packages/harness/deerflow/runtime/runs/worker.py

@@ -90,6 +90,11 @@ async def run_agent(
         # Inject runtime context so middlewares can access thread_id
         # (langgraph-cli does this automatically; we must do it manually)
         runtime = Runtime(context={"thread_id": thread_id}, store=store)
+        # If the caller already set a ``context`` key (LangGraph >= 0.6.0
+        # prefers it over ``configurable`` for thread-level data), make
+        # sure ``thread_id`` is available there too.
+        if "context" in config and isinstance(config["context"], dict):
+            config["context"].setdefault("thread_id", thread_id)
         config.setdefault("configurable", {})["__pregel_runtime"] = runtime
 
         runnable_config = RunnableConfig(**config)