LangGraph graphs with checkpointed/multi-turn state fail the spawn-safety probe

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
58/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Quiet
Tech stack
python
Domain
backend, distributed-systems

Research direction

Start with _register_passthrough_worker in src/conductor/ai/agents/runtime/runtime.py and probe_spawn_safety in src/conductor/ai/agents/runtime/_worker_entries.py, then reproduce the failure with examples/agents/langgraph/03_memory.py. Compare the checkpointed and multi-turn examples with a passing LangGraph example, and verify that 03_memory.py, 13_multi_turn.py, and 27_persistent_memory.py run successfully without the spawn-safety failure.

Written by the indexing model from the issue text.

Description

bug

Files: src/conductor/ai/agents/runtime/runtime.py (_register_passthrough_worker), src/conductor/ai/agents/runtime/_worker_entries.py (probe_spawn_safety)

Symptom: python examples/agents/langgraph/03_memory.py fails in <1s, client-side, before any server call:

SpawnSafetyError: worker 'memory_agent' is not spawn-safe
  AttributeError("Can't get local object 'CompiledStateGraph.attach_node.<locals>._get_updates'")
Define the callable at module level (importable by qualified name).

Cause: The passthrough worker pickles the compiled graph. LangGraph's CompiledStateGraph contains a local closure, so it can never be picklable. The error's advice is unfollowable — the object belongs to LangGraph, not to user code.

Fix: Either avoid pickling the compiled graph in the framework passthrough path, or detect this graph shape and fail with a message naming a supported alternative.

Verify: python examples/agents/langgraph/03_memory.py runs. Same for 13_multi_turn.py and 27_persistent_memory.py.

Scope: 3 of 46 langgraph examples. All three use checkpointed or multi-turn state; the other 43 pass.

Dominant language
Python
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