fix(langgraph): validate ID-mapped resumes before committing them

A resume passed as Command(resume={interrupt_id: value}) is already in
the scratchpad when interrupt() runs, so it took the replay branch, which
queued the RESUME write before validation. A rejected value was therefore
persisted and every later correction re-validated it.

libs/langgraph/langgraph/types.py

@@ -982,9 +982,10 @@ def interrupt(
     # find previous resume values
     if scratchpad.resume:
         if idx < len(scratchpad.resume):
-            conf[CONFIG_KEY_SEND]([(RESUME, scratchpad.resume)])
             v = scratchpad.resume[idx]
-            return adapter.validate_python(v) if adapter else v
+            validated = adapter.validate_python(v) if adapter else v
+            conf[CONFIG_KEY_SEND]([(RESUME, scratchpad.resume)])
+            return validated
     # find current resume value
     v = scratchpad.get_null_resume(True)
     if v is not None:

libs/langgraph/tests/test_interruption.py

@@ -163,8 +163,9 @@ def test_interrupt_response_schema(
     }
 
 
+@pytest.mark.parametrize("resume_style", ["null", "map"])
 def test_interrupt_response_schema_rejects_invalid_resume(
-    sync_checkpointer: BaseCheckpointSaver,
+    sync_checkpointer: BaseCheckpointSaver, resume_style: str
 ) -> None:
     class State(TypedDict):
         answer: Any
@@ -180,10 +181,14 @@ def test_interrupt_response_schema_rejects_invalid_resume(
     )
     config = {"configurable": {"thread_id": "1"}}
     graph.invoke({"answer": None}, config)
+    [pending] = graph.get_state(config).tasks[0].interrupts
+
+    def resume(value: dict[str, Any]) -> Command:
+        return Command(resume=value if resume_style == "null" else {pending.id: value})
 
     with pytest.raises(ValidationError, match="approved"):
-        graph.invoke(Command(resume={"approved": "nope"}), config)
+        graph.invoke(resume({"approved": "nope"}), config)
 
-    assert graph.invoke(Command(resume={"approved": False}), config) == {
+    assert graph.invoke(resume({"approved": False}), config) == {
         "answer": Decision(approved=False)
     }