style(langgraph): fml

libs/langgraph/langgraph/pregel/_loop.py

@@ -248,6 +248,7 @@ class PregelLoop:
         self.retry_policy = retry_policy
         self.cache_policy = cache_policy
         self.durability = durability
+        self.skipped_task_ids: set[str] = set()
         if self.stream is not None and CONFIG_KEY_STREAM in config[CONF]:
             self.stream = DuplexStream(self.stream, config[CONF][CONFIG_KEY_STREAM])
         scratchpad: PregelScratchpad | None = config[CONF].get(CONFIG_KEY_SCRATCHPAD)
@@ -315,15 +316,35 @@ class PregelLoop:
             ]
             writes_to_save: WritesT = [
                 w[1:] for w in self.checkpoint_pending_writes if w[0] == task_id
-            ] + list(writes)
+            ] + [(c, v) for c, v in writes if c != RESUME]
+            self.checkpoint_pending_writes.extend((task_id, c, v) for c, v in writes)
         else:
-            # remove existing writes for this task
+            # build map of existing interrupts for this task: interrupt id -> list of interrupts
+            existing_interrupts_by_id: dict[str, list[Any]] = {
+                v[0].id: v
+                for tid, ch, v in self.checkpoint_pending_writes
+                if tid == task_id and ch == INTERRUPT
+            }
+            writes_to_save = []
+            for ch, v in writes:
+                if ch == INTERRUPT:
+                    # we merge new interrupt writes with existing interrupts writes if they
+                    # occurred within the same task (which means they have the same interrupt id)
+                    new_interrupts = v if isinstance(v, list) else list(v)
+                    if new_interrupts and (
+                        existing := existing_interrupts_by_id.get(new_interrupts[0].id)
+                    ):
+                        v = existing + new_interrupts
+                    writes_to_save.append((ch, v))
+                else:
+                    # we add non-interrupt writes as-is
+                    writes_to_save.append((ch, v))
+
+            # replace all writes for this task_id with the merged writes
             self.checkpoint_pending_writes = [
                 w for w in self.checkpoint_pending_writes if w[0] != task_id
-            ]
-            writes_to_save = writes
-        # save writes
-        self.checkpoint_pending_writes.extend((task_id, c, v) for c, v in writes)
+            ] + [(task_id, c, v) for c, v in writes_to_save]
+
         if self.durability != "exit" and self.checkpointer_put_writes is not None:
             config = patch_configurable(
                 self.checkpoint_config,
@@ -471,6 +492,22 @@ class PregelLoop:
             cache_policy=self.cache_policy,
         )
 
+        resume_map = self.config.get(CONF, {}).get(CONFIG_KEY_RESUME_MAP, {})
+        if resume_map or self.input is None:
+            # do not re-execute tasks that have unresumable interrupts
+            # i.e. when the graph is invoked with None, or the interrupt id is not in the resume map
+            skipped_interrupt_ids = self._pending_interrupts() - set(resume_map)
+            self.skipped_task_ids = {
+                task_id
+                for task_id, channel, value in self.checkpoint_pending_writes
+                if channel == INTERRUPT
+                # interrupts within a task are uncovered sequentially as resumes are provided,
+                # so we only need to check the last interrupt id
+                and value[-1].id in skipped_interrupt_ids
+            }
+        else:
+            self.skipped_task_ids = set()
+
         # produce debug output
         if self._checkpointer_put_after_previous is not None:
             self._emit(
@@ -516,9 +553,45 @@ class PregelLoop:
             if task.writes:
                 self.output_writes(task.id, task.writes, cached=True)
 
+        if self.skipped_task_ids:
+            # remove tasks with writes that have been matched with previous pending writes
+            self.skipped_task_ids = {
+                task_id
+                for task_id in self.skipped_task_ids
+                if not self.tasks[task_id].writes
+            }
+            # output interrupt writes for blocked tasks so they are still visible in the stream
+            for task_id, channel, value in self.checkpoint_pending_writes:
+                if task_id in self.skipped_task_ids and channel == INTERRUPT:
+                    # find resume count for this task
+                    resumes = next(
+                        (
+                            v
+                            for tid, ch, v in self.checkpoint_pending_writes
+                            if tid == task_id and ch == RESUME
+                        ),
+                        None,
+                    )
+                    resume_count = len(resumes) if resumes is not None else 0
+                    # only output unresumed interrupts
+                    if resume_count < len(value):
+                        self.output_writes(task_id, [(INTERRUPT, value[resume_count:])])
+
         return True
 
     def after_tick(self) -> None:
+        if self.skipped_task_ids:
+            # raise early GraphInterrupt for skipped tasks.
+            # since we know len(resumes) < len(interrupts) for these tasks, we
+            # can prevent unnecessary node re-execution by raising early
+            interrupts = []
+            for task_id, channel, value in self.checkpoint_pending_writes:
+                if channel == INTERRUPT and task_id in self.skipped_task_ids:
+                    interrupts.extend(value)
+            if interrupts:
+                raise GraphInterrupt(interrupts)
+
+        self.skipped_task_ids.clear()
         # finish superstep
         writes = [w for t in self.tasks.values() for w in t.writes]
         # all tasks have finished
@@ -570,30 +643,26 @@ class PregelLoop:
 
     def _pending_interrupts(self) -> set[str]:
         """Return the set of interrupt ids that are pending without corresponding resume values."""
-        # mapping of task ids to interrupt ids
-        pending_interrupts: dict[str, str] = {}
+        # mapping of task ids to (interrupt_id, interrupt_count)
+        pending_interrupts: dict[str, tuple[str, int]] = {}
+        # mapping of task ids to resume count
+        pending_resumes: dict[str, int] = {}
 
-        # set of resume task ids
-        pending_resumes: set[str] = set()
+        for task_id, channel, value in self.checkpoint_pending_writes:
+            if channel == INTERRUPT:
+                pending_interrupts[task_id] = (
+                    value[0].id,
+                    len(value),
+                )
+            elif channel == RESUME:
+                resume_list = value if isinstance(value, list) else [value]
+                pending_resumes[task_id] = len(resume_list)
 
-        for task_id, write_type, value in self.checkpoint_pending_writes:
-            if write_type == INTERRUPT:
-                # interrupts is always a list, but there should only be one element
-                pending_interrupts[task_id] = value[0].id
-            elif write_type == RESUME:
-                pending_resumes.add(task_id)
-
-        resumed_interrupt_ids = {
-            pending_interrupts[task_id]
-            for task_id in pending_resumes
-            if task_id in pending_interrupts
-        }
-
-        # Keep only interrupts whose interrupt_id is not resumed
+        # keep only interrupt ids where resume_count < interrupt_count
         hanging_interrupts: set[str] = {
             interrupt_id
-            for interrupt_id in pending_interrupts.values()
-            if interrupt_id not in resumed_interrupt_ids
+            for task_id, (interrupt_id, interrupt_count) in pending_interrupts.items()
+            if pending_resumes.get(task_id, 0) < interrupt_count
         }
 
         return hanging_interrupts
@@ -1026,6 +1095,7 @@ class SyncPregelLoop(PregelLoop, AbstractContextManager):
 
     def put_writes(self, task_id: str, writes: WritesT) -> None:
         """Put writes for a task, to be read by the next tick."""
+
         super().put_writes(task_id, writes)
         if not writes or self.cache is None or not hasattr(self, "tasks"):
             return

libs/langgraph/langgraph/pregel/main.py

@@ -2672,7 +2672,11 @@ class Pregel(
                     for task in loop.match_cached_writes():
                         loop.output_writes(task.id, task.writes, cached=True)
                     for _ in runner.tick(
-                        [t for t in loop.tasks.values() if not t.writes],
+                        [
+                            t
+                            for t in loop.tasks.values()
+                            if not t.writes and t.id not in loop.skipped_task_ids
+                        ],
                         timeout=self.step_timeout,
                         get_waiter=get_waiter,
                         schedule_task=loop.accept_push,
@@ -2991,7 +2995,11 @@ class Pregel(
                         for task in await loop.amatch_cached_writes():
                             loop.output_writes(task.id, task.writes, cached=True)
                         async for _ in runner.atick(
-                            [t for t in loop.tasks.values() if not t.writes],
+                            [
+                                t
+                                for t in loop.tasks.values()
+                                if not t.writes and t.id not in loop.skipped_task_ids
+                            ],
                             timeout=self.step_timeout,
                             get_waiter=get_waiter,
                             schedule_task=loop.aaccept_push,

libs/langgraph/tests/test_interruption.py

@@ -1,12 +1,21 @@
+import operator
+import sys
+from typing import Annotated
+
 import pytest
 from langgraph.checkpoint.base import BaseCheckpointSaver
 from typing_extensions import TypedDict
 
 from langgraph.graph import END, START, StateGraph
-from langgraph.types import Durability
+from langgraph.types import Command, Durability, Send, interrupt
 
 pytestmark = pytest.mark.anyio
 
+NEEDS_CONTEXTVARS = pytest.mark.skipif(
+    sys.version_info < (3, 11),
+    reason="Python 3.11+ is required for async contextvars support",
+)
+
 
 def test_interruption_without_state_updates(
     sync_checkpointer: BaseCheckpointSaver, durability: Durability
@@ -90,3 +99,567 @@ async def test_interruption_without_state_updates_async(
     assert (await graph.aget_state(thread)).next == ()
     n_checkpoints = len([c async for c in graph.aget_state_history(thread)])
     assert n_checkpoints == (5 if durability != "exit" else 3)
+
+
+def test_interrupt_with_send_payloads(sync_checkpointer: BaseCheckpointSaver) -> None:
+    """Test interruption in map node with Send payloads and human-in-the-loop resume."""
+
+    # Global counter to track node executions
+    node_counter = {"entry": 0, "map_node": 0}
+
+    class State(TypedDict):
+        items: list[str]
+        processed: Annotated[list[str], operator.add]
+
+    def entry_node(state: State):
+        node_counter["entry"] += 1
+        return {}  # No state updates in entry node
+
+    def send_to_map(state: State):
+        return [Send("map_node", {"item": item}) for item in state["items"]]
+
+    def map_node(state: State):
+        node_counter["map_node"] += 1
+        if "dangerous" in state["item"]:
+            value = interrupt({"processing": state["item"]})
+            return {"processed": [f"processed_{value}"]}
+        else:
+            return {"processed": [f"processed_{state['item']}_auto"]}
+
+    builder = StateGraph(State)
+    builder.add_node("entry", entry_node)
+    builder.add_node("map_node", map_node)
+    builder.add_edge(START, "entry")
+    builder.add_conditional_edges("entry", send_to_map, ["map_node"])
+    builder.add_edge("map_node", END)
+
+    graph = builder.compile(checkpointer=sync_checkpointer)
+
+    config = {"configurable": {"thread_id": "test_interrupt_send"}}
+
+    # Run until interrupts
+    result = graph.invoke(
+        {"items": ["item1", "dangerous_item1", "dangerous_item2"]}, config=config
+    )
+
+    # Verify we have interrupts (only one for dangerous_item)
+    interrupts = result.get("__interrupt__", [])
+    assert len(interrupts) == 2
+    assert "dangerous_item" in interrupts[0].value["processing"]
+
+    # Resume with mapping of interrupt IDs to values
+    resume_map = {i.id: f"human_input_{i.value['processing']}" for i in interrupts}
+
+    final_result = graph.invoke(Command(resume=resume_map), config=config)
+
+    # Verify final result contains processed items
+    assert "processed" in final_result
+    processed_items = final_result["processed"]
+    assert len(processed_items) == 3
+    assert "processed_item1_auto" in processed_items  # item1 processed automatically
+    assert any(
+        "processed_human_input_dangerous_item1" in item for item in processed_items
+    )  # dangerous_item1 processed after interrupt
+    assert any(
+        "processed_human_input_dangerous_item2" in item for item in processed_items
+    )  # dangerous_item2 processed after interrupt
+
+    # Verify node execution counts
+    assert node_counter["entry"] == 1  # Entry node runs once
+    # Map node runs 3 times initially (item1 completes, 2 dangerous_items interrupt),
+    # then 2 times on resume
+    assert node_counter["map_node"] == 5
+
+
+@NEEDS_CONTEXTVARS
+async def test_interrupt_with_send_payloads_async(
+    async_checkpointer: BaseCheckpointSaver, durability: Durability
+) -> None:
+    """Test interruption in map node with Send payloads and human-in-the-loop resume."""
+
+    # Global counter to track node executions
+    node_counter = {"entry": 0, "map_node": 0}
+
+    class State(TypedDict):
+        items: list[str]
+        processed: Annotated[list[str], operator.add]
+
+    def entry_node(state: State):
+        node_counter["entry"] += 1
+        return {}  # No state updates in entry node
+
+    def send_to_map(state: State):
+        return [Send("map_node", {"item": item}) for item in state["items"]]
+
+    def map_node(state: State):
+        node_counter["map_node"] += 1
+        if "dangerous" in state["item"]:
+            value = interrupt({"processing": state["item"]})
+            return {"processed": [f"processed_{value}"]}
+        else:
+            return {"processed": [f"processed_{state['item']}_auto"]}
+
+    builder = StateGraph(State)
+    builder.add_node("entry", entry_node)
+    builder.add_node("map_node", map_node)
+    builder.add_edge(START, "entry")
+    builder.add_conditional_edges("entry", send_to_map, ["map_node"])
+    builder.add_edge("map_node", END)
+
+    graph = builder.compile(checkpointer=async_checkpointer)
+
+    config = {"configurable": {"thread_id": "test_interrupt_send"}}
+
+    # Run until interrupts
+    result = await graph.ainvoke(
+        {"items": ["item1", "dangerous_item1", "dangerous_item2"]}, config=config
+    )
+
+    # Verify we have interrupts (only one for dangerous_item)
+    interrupts = result.get("__interrupt__", [])
+    assert len(interrupts) == 2
+    assert "dangerous_item" in interrupts[0].value["processing"]
+
+    # Resume with mapping of interrupt IDs to values
+    resume_map = {i.id: f"human_input_{i.value['processing']}" for i in interrupts}
+
+    final_result = await graph.ainvoke(Command(resume=resume_map), config=config)
+
+    # Verify final result contains processed items
+    assert "processed" in final_result
+    processed_items = final_result["processed"]
+    assert len(processed_items) == 3
+    assert "processed_item1_auto" in processed_items  # item1 processed automatically
+    assert any(
+        "processed_human_input_dangerous_item1" in item for item in processed_items
+    )  # dangerous_item1 processed after interrupt
+    assert any(
+        "processed_human_input_dangerous_item2" in item for item in processed_items
+    )  # dangerous_item2 processed after interrupt
+
+    # Verify node execution counts
+    assert node_counter["entry"] == 1  # Entry node runs once
+    # Map node runs 3 times initially (item1 completes, 2 dangerous_items interrupt),
+    # then 2 times on resume
+    assert node_counter["map_node"] == 5
+
+
+def test_interrupt_with_send_payloads_sequential_resume(
+    sync_checkpointer: BaseCheckpointSaver,
+) -> None:
+    """Test interruption in map node with Send payloads and sequential resume."""
+
+    # Global counter to track node executions
+    node_counter = {"entry": 0, "map_node": 0}
+
+    class State(TypedDict):
+        items: list[str]
+        processed: Annotated[list[str], operator.add]
+
+    def entry_node(state: State):
+        node_counter["entry"] += 1
+        return {}  # No state updates in entry node
+
+    def send_to_map(state: State):
+        return [Send("map_node", {"item": item}) for item in state["items"]]
+
+    def map_node(state: State):
+        node_counter["map_node"] += 1
+        if "dangerous" in state["item"]:
+            value = interrupt({"processing": state["item"]})
+            return {"processed": [f"processed_{value}"]}
+        else:
+            return {"processed": [f"processed_{state['item']}_auto"]}
+
+    builder = StateGraph(State)
+    builder.add_node("entry", entry_node)
+    builder.add_node("map_node", map_node)
+    builder.add_edge(START, "entry")
+    builder.add_conditional_edges("entry", send_to_map, ["map_node"])
+    builder.add_edge("map_node", END)
+
+    graph = builder.compile(checkpointer=sync_checkpointer)
+
+    config = {"configurable": {"thread_id": "test_interrupt_send_sequential"}}
+
+    # Run until interrupts
+    result = graph.invoke(
+        {"items": ["item1", "dangerous_item1", "dangerous_item2"]}, config=config
+    )
+
+    # Verify we have interrupts
+    interrupts = result.get("__interrupt__", [])
+    assert len(interrupts) == 2
+    assert "dangerous_item" in interrupts[0].value["processing"]
+
+    # Resume first interrupt only
+    first_interrupt = interrupts[0]
+    first_resume_map = {
+        first_interrupt.id: f"human_input_{first_interrupt.value['processing']}"
+    }
+
+    partial_result = graph.invoke(Command(resume=first_resume_map), config=config)
+
+    # Verify we still have one pending interrupt
+    remaining_interrupts = partial_result.get("__interrupt__", [])
+    assert len(remaining_interrupts) == 1
+
+    # Resume second interrupt
+    second_interrupt = remaining_interrupts[0]
+    second_resume_map = {
+        second_interrupt.id: f"human_input_{second_interrupt.value['processing']}"
+    }
+
+    final_result = graph.invoke(Command(resume=second_resume_map), config=config)
+
+    # Verify final result contains processed items
+    assert "processed" in final_result
+    processed_items = final_result["processed"]
+    assert len(processed_items) == 3
+    assert "processed_item1_auto" in processed_items  # item1 processed automatically
+    assert any(
+        "processed_human_input_dangerous_item1" in item for item in processed_items
+    )  # dangerous_item1 processed after interrupt
+    assert any(
+        "processed_human_input_dangerous_item2" in item for item in processed_items
+    )  # dangerous_item2 processed after interrupt
+
+    # Verify node execution counts
+    assert node_counter["entry"] == 1  # Entry node runs once
+    # Map node runs 3 times initially (item1 completes, 2 dangerous_items interrupt),
+    # then 1 time on first resume, then 1 time on second resume
+    assert node_counter["map_node"] == 5
+
+
+@NEEDS_CONTEXTVARS
+async def test_interrupt_with_send_payloads_sequential_resume_async(
+    async_checkpointer: BaseCheckpointSaver,
+) -> None:
+    """Test interruption in map node with Send payloads and sequential resume."""
+
+    # Global counter to track node executions
+    node_counter = {"entry": 0, "map_node": 0}
+
+    class State(TypedDict):
+        items: list[str]
+        processed: Annotated[list[str], operator.add]
+
+    def entry_node(state: State):
+        node_counter["entry"] += 1
+        return {}  # No state updates in entry node
+
+    def send_to_map(state: State):
+        return [Send("map_node", {"item": item}) for item in state["items"]]
+
+    def map_node(state: State):
+        node_counter["map_node"] += 1
+        if "dangerous" in state["item"]:
+            value = interrupt({"processing": state["item"]})
+            return {"processed": [f"processed_{value}"]}
+        else:
+            return {"processed": [f"processed_{state['item']}_auto"]}
+
+    builder = StateGraph(State)
+    builder.add_node("entry", entry_node)
+    builder.add_node("map_node", map_node)
+    builder.add_edge(START, "entry")
+    builder.add_conditional_edges("entry", send_to_map, ["map_node"])
+    builder.add_edge("map_node", END)
+
+    graph = builder.compile(checkpointer=async_checkpointer)
+
+    config = {"configurable": {"thread_id": "test_interrupt_send_sequential"}}
+
+    # Run until interrupts
+    result = await graph.ainvoke(
+        {"items": ["item1", "dangerous_item1", "dangerous_item2"]}, config=config
+    )
+
+    # Verify we have interrupts
+    interrupts = result.get("__interrupt__", [])
+    assert len(interrupts) == 2
+    assert "dangerous_item" in interrupts[0].value["processing"]
+
+    # Resume first interrupt only
+    first_interrupt = interrupts[0]
+    first_resume_map = {
+        first_interrupt.id: f"human_input_{first_interrupt.value['processing']}"
+    }
+
+    partial_result = await graph.ainvoke(
+        Command(resume=first_resume_map), config=config
+    )
+
+    # Verify we still have one pending interrupt
+    remaining_interrupts = partial_result.get("__interrupt__", [])
+    assert len(remaining_interrupts) == 1
+
+    # Resume second interrupt
+    second_interrupt = remaining_interrupts[0]
+    second_resume_map = {
+        second_interrupt.id: f"human_input_{second_interrupt.value['processing']}"
+    }
+
+    final_result = await graph.ainvoke(Command(resume=second_resume_map), config=config)
+
+    # Verify final result contains processed items
+    assert "processed" in final_result
+    processed_items = final_result["processed"]
+    assert len(processed_items) == 3
+    assert "processed_item1_auto" in processed_items  # item1 processed automatically
+    assert any(
+        "processed_human_input_dangerous_item1" in item for item in processed_items
+    )  # dangerous_item1 processed after interrupt
+    assert any(
+        "processed_human_input_dangerous_item2" in item for item in processed_items
+    )  # dangerous_item2 processed after interrupt
+
+    # Verify node execution counts
+    assert node_counter["entry"] == 1  # Entry node runs once
+    # Map node runs 3 times initially (item1 completes, 2 dangerous_items interrupt),
+    # then 1 time on first resume, then 1 time on second resume
+    assert node_counter["map_node"] == 5
+
+
+def test_node_with_multiple_interrupts_requires_full_resume(
+    sync_checkpointer: BaseCheckpointSaver,
+) -> None:
+    """Test a number of different resume patterns for a node with multiple interrupts,
+
+    Ensures that a node is not re-executed until valid resume values have been provided to all
+    discovered interrupts"""
+
+    node_counter = 0
+
+    class State(TypedDict):
+        input: str
+
+    def double_interrupt_node(state: State):
+        nonlocal node_counter
+        node_counter += 1
+        first = interrupt("first")
+        second = interrupt("second")
+        third = interrupt("third")
+        return {"input": f"{first}-{second}-{third}"}
+
+    builder = StateGraph(State)
+    builder.add_node("double_interrupt", double_interrupt_node)
+    builder.add_edge(START, "double_interrupt")
+    builder.add_edge("double_interrupt", END)
+
+    graph = builder.compile(checkpointer=sync_checkpointer)
+
+    config = {"configurable": {"thread_id": "test_double_interrupt"}}
+
+    result = graph.invoke({"input": "start"}, config=config)
+
+    interrupts = result.get("__interrupt__", [])
+    assert len(interrupts) == 1
+    first_interrupt = interrupts[0]
+    assert node_counter == 1
+
+    # invoke with an interrupt map that matches double_interrupt_node.
+    # this should execute the node
+    partial = graph.invoke(
+        Command(resume={first_interrupt.id: "human_first"}), config=config
+    )
+    remaining_interrupts = partial.get("__interrupt__", [])
+    assert len(remaining_interrupts) == 1
+    assert remaining_interrupts[0].value == "second"
+    assert node_counter == 2
+
+    # invoke with an interrupt map that DOES NOT match double_interrupt_node.
+    # this should not execute the node because the optimization kicks in
+    partial = graph.invoke(
+        Command(resume={"00000000000000000000000000000000": "nothing_burger"}),
+        config=config,
+    )
+    remaining_interrupts = partial.get("__interrupt__", [])
+    assert len(remaining_interrupts) == 1
+    assert remaining_interrupts[0].value == "second"
+    assert node_counter == 2
+
+    # invoke with None resume. this should NOT execute the node
+    partial = graph.invoke(None, config=config)
+    remaining_interrupts = partial.get("__interrupt__", [])
+    assert len(remaining_interrupts) == 1
+    assert remaining_interrupts[0].value == "second"
+    assert node_counter == 2
+
+    # invoke with nonspecific resume. this should execute the node
+    partial = graph.invoke(Command(resume="human_second"), config=config)
+    remaining_interrupts = partial.get("__interrupt__", [])
+    assert len(remaining_interrupts) == 1
+    print("REMAINING INTERRUPTS: ", remaining_interrupts)
+    assert remaining_interrupts[0].value == "third"
+    assert node_counter == 3
+
+    # finally, invoke with an interrupt map that matches double_interrupt_node.
+    # this should execute the node and all interrupts should be resolved
+    final_result = graph.invoke(Command(resume="human_third"), config=config)
+    assert "input" in final_result
+    assert final_result["input"] == "human_first-human_second-human_third"
+    assert node_counter == 4
+
+
+@NEEDS_CONTEXTVARS
+async def test_node_with_multiple_interrupts_requires_full_resume_async(
+    async_checkpointer: BaseCheckpointSaver,
+) -> None:
+    """Test a number of different resume patterns for a node with multiple interrupts,
+
+    Ensures that a node is not re-executed until valid resume values have been provided to all
+    discovered interrupts"""
+
+    node_counter = 0
+
+    class State(TypedDict):
+        input: str
+
+    def double_interrupt_node(state: State):
+        nonlocal node_counter
+        node_counter += 1
+        first = interrupt("first")
+        second = interrupt("second")
+        third = interrupt("third")
+        return {"input": f"{first}-{second}-{third}"}
+
+    builder = StateGraph(State)
+    builder.add_node("double_interrupt", double_interrupt_node)
+    builder.add_edge(START, "double_interrupt")
+    builder.add_edge("double_interrupt", END)
+
+    graph = builder.compile(checkpointer=async_checkpointer)
+
+    config = {"configurable": {"thread_id": "test_double_interrupt"}}
+
+    result = await graph.ainvoke({"input": "start"}, config=config)
+
+    interrupts = result.get("__interrupt__", [])
+    assert len(interrupts) == 1
+    first_interrupt = interrupts[0]
+    assert node_counter == 1
+
+    # invoke with an interrupt map that matches double_interrupt_node.
+    # this should execute the node
+    partial = await graph.ainvoke(
+        Command(resume={first_interrupt.id: "human_first"}), config=config
+    )
+    remaining_interrupts = partial.get("__interrupt__", [])
+    assert len(remaining_interrupts) == 1
+    assert remaining_interrupts[0].value == "second"
+    assert node_counter == 2
+
+    # invoke with an interrupt map that DOES NOT match double_interrupt_node.
+    # this should not execute the node because the optimization kicks in
+    partial = await graph.ainvoke(
+        Command(resume={"00000000000000000000000000000000": "nothing_burger"}),
+        config=config,
+    )
+    remaining_interrupts = partial.get("__interrupt__", [])
+    assert len(remaining_interrupts) == 1
+    assert remaining_interrupts[0].value == "second"
+    assert node_counter == 2
+
+    # invoke with None resume. this should NOT execute the node
+    partial = await graph.ainvoke(None, config=config)
+    remaining_interrupts = partial.get("__interrupt__", [])
+    assert len(remaining_interrupts) == 1
+    assert remaining_interrupts[0].value == "second"
+    assert node_counter == 2
+
+    # invoke with nonspecific resume. this should execute the node
+    partial = await graph.ainvoke(Command(resume="human_second"), config=config)
+    remaining_interrupts = partial.get("__interrupt__", [])
+    assert len(remaining_interrupts) == 1
+    print("REMAINING INTERRUPTS: ", remaining_interrupts)
+    assert remaining_interrupts[0].value == "third"
+    assert node_counter == 3
+
+    # finally, invoke with an interrupt map that matches double_interrupt_node.
+    # this should execute the node and all interrupts should be resolved
+    final_result = await graph.ainvoke(Command(resume="human_third"), config=config)
+    assert "input" in final_result
+    assert final_result["input"] == "human_first-human_second-human_third"
+    assert node_counter == 4
+
+
+def test_invoke_interrupted_graph_with_none(
+    sync_checkpointer: BaseCheckpointSaver,
+) -> None:
+    """Test that invoking an interrupted graph with None does not duplicate interrupt writes"""
+
+    node_counter = 0
+
+    class State(TypedDict):
+        input: str
+
+    def double_interrupt_node(state: State):
+        nonlocal node_counter
+        node_counter += 1
+        first = interrupt("first")
+        second = interrupt("second")
+        return {"input": f"{first}-{second}"}
+
+    builder = StateGraph(State)
+    builder.add_node("double_interrupt", double_interrupt_node)
+    builder.add_edge(START, "double_interrupt")
+    builder.add_edge("double_interrupt", END)
+
+    graph = builder.compile(checkpointer=sync_checkpointer)
+
+    config = {"configurable": {"thread_id": "test_none_resume"}}
+
+    result = graph.invoke({"input": "start"}, config=config)
+    first_history = list(graph.get_state_history(config))
+    interrupts = result.get("__interrupt__", [])
+    assert len(interrupts) == 1
+    assert node_counter == 1
+
+    # invoke with None. this should NOT execute the node and the history should
+    # look the same as the first run
+    partial = graph.invoke(None, config=config)
+    second_history = list(graph.get_state_history(config))
+    remaining_interrupts = partial.get("__interrupt__", [])
+    assert len(remaining_interrupts) == 1
+    assert remaining_interrupts[0].value == "first"
+    assert node_counter == 1
+
+    # history should look the same for tasks and interrupts
+    print("first_history[0].interrupts: ", first_history[0].interrupts)
+    print("second_history[0].interrupts: ", second_history[0].interrupts)
+    print("first_history[0].tasks: ", first_history[0].tasks)
+    print("second_history[0].tasks: ", second_history[0].tasks)
+    assert first_history[0].interrupts == second_history[0].interrupts
+    assert first_history[0].tasks == second_history[0].tasks
+
+    # now resume the first interrupt with some value
+    partial = graph.invoke(Command(resume="weet"), config=config)
+    print("partial 3", partial)
+    third_history = list(graph.get_state_history(config))
+    remaining_interrupts = partial.get("__interrupt__", [])
+    assert len(remaining_interrupts) == 1
+    assert remaining_interrupts[0].value == "second"
+    assert node_counter == 2
+
+    # invoke with None again. the history should look the same as
+    # the third run
+    partial = graph.invoke(None, config=config)
+    print("partial 4", partial)
+    fourth_history = list(graph.get_state_history(config))
+    remaining_interrupts = partial.get("__interrupt__", [])
+    assert len(remaining_interrupts) == 1
+    assert node_counter == 2
+
+    print("\nthird_history[0].interrupts: ", third_history[0].interrupts)
+    print("fourth_history[0].interrupts: ", fourth_history[0].interrupts)
+    print("third_history[0].tasks: ", third_history[0].tasks)
+    print("fourth_history[0].tasks: ", fourth_history[0].tasks)
+    assert third_history[0].interrupts == fourth_history[0].interrupts
+    assert third_history[0].tasks == fourth_history[0].tasks
+
+    # resume the graph once more with a real value
+    partial = graph.invoke(Command(resume="bix"), config=config)
+    remaining_interrupts = partial.get("__interrupt__", [])
+    assert len(remaining_interrupts) == 0
+    assert node_counter == 3

libs/langgraph/tests/test_large_cases.py

@@ -4726,7 +4726,7 @@ def test_send_dedupe_on_resume(
     assert len(history) == (4 if durability != "exit" else 1)
 
     # resume execution
-    assert graph.invoke(None, thread1, durability=durability) == [
+    assert graph.invoke(Command(resume=""), thread1, durability=durability) == [
         "0",
         "1",
         "3.1",

libs/langgraph/tests/test_pregel_async.py

@@ -2545,7 +2545,7 @@ async def test_send_dedupe_on_resume(
     assert builder.nodes["2"].runnable.func.ticks == 3
     assert builder.nodes["flaky"].runnable.func.ticks == 1
     # resume execution
-    assert await graph.ainvoke(None, thread1, durability=durability) == [
+    assert await graph.ainvoke(Command(resume=""), thread1, durability=durability) == [
         "0",
         "1",
         "3.1",