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Closes #8038 ## Description The `ensure_config` merge introduced in #7926 caused a child graph invoked inside a parent node to inherit the parent task's `checkpoint_ns` from the ambient run context (`var_child_runnable_config`), so the child's checkpoints were written under an unreadable namespace and re-ran from scratch each turn (#8038). The first explicitly passed `configurable` that carries a checkpoint coordinate (a `thread_id`, or any `checkpoint_ns`/`checkpoint_id`/`checkpoint_map`) now replaces the ambient one, while subsequent explicit configs still shallow-merge — preserving #7926's `with_config(...)` semantics. ## Contract `ensure_config` merges an explicit `configurable` over the ambient run context (`var_child_runnable_config`) with one rule: **an explicit `configurable` that supplies its own checkpoint coordinate addresses its own checkpoint lineage, so the ambient `configurable` is dropped rather than merged over.** Coordinate keys are `thread_id`, `checkpoint_ns`, `checkpoint_id`, and `checkpoint_map` (grouped as `_CHECKPOINT_COORDINATE_KEYS`). A non-coordinate `configurable` keeps the ambient and shallow-merges over it. Below, each case shows the parent/child graph wiring that triggers it and the resulting namespacing. The child is always a compiled subgraph invoked from inside a parent node. ### 1. Subgraph invoked with no new config → ambient inherited ```python child = StateGraph(ChildState).add_node("n", child_node).add_edge(START, "n").compile(checkpointer=checkpointer) def parent_node(state): child.invoke({}, config=None) # no explicit configurable return {"result": "ok"} parent = StateGraph(ParentState).add_node("p", parent_node).add_edge(START, "p").compile(checkpointer=checkpointer) parent.invoke({"result": ""}, config={"configurable": {"thread_id": "parent"}}) ``` Child inherits the parent task's `checkpoint_ns` (`p:<parent-task>`); its checkpoints are written as a discoverable child of the parent run. Pre-#7926 behavior, unchanged. ### 2. Subgraph invoked with a new thread_id → ambient dropped ```python child = StateGraph(ChildState).add_node("n", child_node).add_edge(START, "n").compile(checkpointer=checkpointer) child_config = {"configurable": {"thread_id": str(uuid4())}} def parent_node(state): child.invoke({}, config=child_config) # explicit new thread_id return {"result": "ok"} parent = StateGraph(ParentState).add_node("p", parent_node).add_edge(START, "p").compile(checkpointer=checkpointer) parent.invoke({"result": ""}, config={"configurable": {"thread_id": "parent"}}) ``` Child starts its own lineage on `child_config`'s thread; `checkpoint_ns == ""`; `child.get_state(child_config)` reads back state across repeated parent turns. Fixes #8038. ### 3. Subgraph invoked with the same thread_id as parent → ambient still dropped ```python child = StateGraph(ChildState).add_node("n", child_node).add_edge(START, "n").compile(checkpointer=checkpointer) def parent_node(state): # reuses the parent's thread_id as the child's own child.invoke({}, config={"configurable": {"thread_id": state["parent_thread"]}}) return {"result": "ok"} parent = StateGraph(ParentState).add_node("p", parent_node).add_edge(START, "p").compile(checkpointer=checkpointer) parent_thread = str(uuid4()) parent.invoke({"parent_thread": parent_thread, "result": ""}, config={"configurable": {"thread_id": parent_thread}}) ``` Child addresses its own root namespace on the shared thread; `checkpoint_ns == ""`. The parent task's `checkpoint_ns` must not leak in, or `child.get_state({"configurable": {"thread_id": parent_thread}})` returns empty state and the child re-runs from scratch each turn. ### 4. Subagent invoked with a non-coordinate key only → ambient inherited ```python child = StateGraph(ChildState).add_node("n", child_node).add_edge(START, "n").compile(checkpointer=checkpointer) def parent_node(state): # ls_agent_type is not a checkpoint coordinate, so ambient is kept child.invoke({}, config={"configurable": {"ls_agent_type": "subagent"}}) return {"result": "ok"} parent = StateGraph(ParentState).add_node("p", parent_node).add_edge(START, "p").compile(checkpointer=checkpointer) parent.invoke({"result": ""}, config={"configurable": {"thread_id": "parent"}}) ``` Child remains a discoverable child of the parent run; ambient `thread_id` and `checkpoint_ns` preserved (deepagents `task` tool pattern). ### 5. with_config(...) + invoke-time thread_id → ambient dropped, then merged ```python # child compiled with a non-coordinate configurable via with_config child = ( StateGraph(ChildState) .add_node("n", child_node) .add_edge(START, "n") .compile(checkpointer=checkpointer) .with_config({"configurable": {"ls_agent_type": "root"}}) ) def parent_node(state): # invoke-time config supplies the thread_id; with_config's ls_agent_type survives child.invoke({}, config={"configurable": {"thread_id": "child"}}) return {"result": "ok"} parent = StateGraph(ParentState).add_node("p", parent_node).add_edge(START, "p").compile(checkpointer=checkpointer) parent.invoke({"result": ""}, config={"configurable": {"thread_id": "parent"}}) ``` First coordinate-bearing config (`thread_id`) drops the ambient; subsequent explicit configs still shallow-merge, so `ls_agent_type` survives alongside `thread_id`. Preserves #7926 `with_config(...)` semantics. ### Regression note Cases 1, 4, and 5 are the pre-#7926 behavior and are preserved unchanged. Cases 2 and 3 fix the regression introduced by #7926: an explicit `thread_id` resets the ambient even when it equals the ambient thread id, because a child reusing the parent's thread id still addresses its own root namespace on that thread, not the parent task's. ## Self-Hosted Release Note Fix regression where a nested subgraph with its own `thread_id` invoked inside a parent node lost its persisted state across turns. ## Test Plan - [x] `pytest tests/test_subgraph_persistence.py -k test_child_with_own_thread_id_keeps_namespace` (case 2) - [x] `pytest tests/test_utils.py -k ensure_config_explicit_configurable_replaces_ambient` (case 2) - [x] `pytest tests/test_utils.py -k ensure_config_ambient_inherited_when_no_explicit_configurable` (case 1) - [x] `pytest tests/test_utils.py -k ensure_config_non_coordinate_config_keeps_ambient_checkpoint_ns` (case 4) - [x] `pytest tests/test_utils.py -k ensure_config_explicit_configurables_still_merge_over_ambient` (case 5) - [x] `pytest tests/test_utils.py -k ensure_config_same_thread_id_still_clears_ambient` (case 3) Made by [Open SWE](https://openswe.vercel.app) --------- Co-authored-by: Nick Hollon <274035459+nick-hollon-lc@users.noreply.github.com> Co-authored-by: open-swe[bot] <open-swe@users.noreply.github.com>