feat(langchain): improved HITL patterns (#32996)

# Main changes / new features

## Better support for parallel tool calls

1. Support for multiple tool calls requiring human input
2. Support for combination of tool calls requiring human input + those
that are auto-approved
3. Support structured output w/ tool calls requiring human input
4. Support structured output w/ standard tool calls

## Shortcut for allowed actions

Adds a shortcut where tool config can be specified as a `bool`, meaning
"all actions allowed"

```py
HumanInTheLoopMiddleware(tool_configs={"expensive_tool": True})
```

## A few design decisions here
* We only raise one interrupt w/ all `HumanInterrupt`s, currently we
won't be able to execute all tools until all of these are resolved. This
isn't super blocking bc we can't re-invoke the model until all tools
have finished execution. That being said, if you have a long running
auto-approved tool, this could slow things down.

## TODOs

* Ideally, we would rename `accept` -> `approve`
* Ideally, we would rename `respond` -> `reject`
* Docs update (@sydney-runkle to own)
* In another PR I'd like to refactor testing to have one file for each
prebuilt middleware :)

Fast follow to https://github.com/langchain-ai/langchain/pull/32962
which was deemed as too breaking

libs/langchain_v1/langchain/agents/interrupt.py

@@ -1,97 +0,0 @@
-"""Interrupt types to use with agent inbox like setups."""
-
-from typing import Literal
-
-from typing_extensions import TypedDict
-
-
-class HumanInterruptConfig(TypedDict):
-    """Configuration that defines what actions are allowed for a human interrupt.
-
-    This controls the available interaction options when the graph is paused for human input.
-
-    Attributes:
-        allow_ignore: Whether the human can choose to ignore/skip the current step
-        allow_respond: Whether the human can provide a text response/feedback
-        allow_edit: Whether the human can edit the provided content/state
-        allow_accept: Whether the human can accept/approve the current state
-    """
-
-    allow_ignore: bool
-    allow_respond: bool
-    allow_edit: bool
-    allow_accept: bool
-
-
-class ActionRequest(TypedDict):
-    """Represents a request for human action within the graph execution.
-
-    Contains the action type and any associated arguments needed for the action.
-
-    Attributes:
-        action: The type or name of action being requested (e.g., "Approve XYZ action")
-        args: Key-value pairs of arguments needed for the action
-    """
-
-    action: str
-    args: dict
-
-
-class HumanInterrupt(TypedDict):
-    """Represents an interrupt triggered by the graph that requires human intervention.
-
-    This is passed to the `interrupt` function when execution is paused for human input.
-
-    Attributes:
-        action_request: The specific action being requested from the human
-        config: Configuration defining what actions are allowed
-        description: Optional detailed description of what input is needed
-
-    Example:
-        ```python
-        # Extract a tool call from the state and create an interrupt request
-        request = HumanInterrupt(
-            action_request=ActionRequest(
-                action="run_command",  # The action being requested
-                args={"command": "ls", "args": ["-l"]},  # Arguments for the action
-            ),
-            config=HumanInterruptConfig(
-                allow_ignore=True,  # Allow skipping this step
-                allow_respond=True,  # Allow text feedback
-                allow_edit=False,  # Don't allow editing
-                allow_accept=True,  # Allow direct acceptance
-            ),
-            description="Please review the command before execution",
-        )
-        # Send the interrupt request and get the response
-        response = interrupt([request])[0]
-        ```
-    """
-
-    action_request: ActionRequest
-    config: HumanInterruptConfig
-    description: str | None
-
-
-class HumanResponse(TypedDict):
-    """Human response.
-
-    The response provided by a human to an interrupt,
-    which is returned when graph execution resumes.
-
-    Attributes:
-        type: The type of response:
-
-            - "accept": Approves the current state without changes
-            - "ignore": Skips/ignores the current step
-            - "response": Provides text feedback or instructions
-            - "edit": Modifies the current state/content
-        args: The response payload:
-
-            - None: For ignore/accept actions
-            - str: For text responses
-            - ActionRequest: For edit actions with updated content
-    """
-
-    type: Literal["accept", "ignore", "response", "edit"]
-    args: None | str | ActionRequest

libs/langchain_v1/langchain/agents/middleware/_utils.py

@@ -1,11 +0,0 @@
-"""Utility functions for middleware."""
-
-from typing import Any
-
-
-def _generate_correction_tool_messages(content: str, tool_calls: list) -> list[dict[str, Any]]:
-    """Generate tool messages for model behavior correction."""
-    return [
-        {"role": "tool", "content": content, "tool_call_id": tool_call["id"]}
-        for tool_call in tool_calls
-    ]

libs/langchain_v1/langchain/agents/middleware/human_in_the_loop.py

@@ -1,19 +1,110 @@
 """Human in the loop middleware."""
 
-from typing import Any
+from typing import Any, Literal
 
-from langgraph.prebuilt.interrupt import (
-    ActionRequest,
-    HumanInterrupt,
-    HumanInterruptConfig,
-    HumanResponse,
-)
+from langchain_core.messages import AIMessage, ToolCall, ToolMessage
 from langgraph.types import interrupt
+from typing_extensions import NotRequired, TypedDict
 
-from langchain.agents.middleware._utils import _generate_correction_tool_messages
 from langchain.agents.middleware.types import AgentMiddleware, AgentState
 
-ToolInterruptConfig = dict[str, HumanInterruptConfig]
+
+class HumanInTheLoopConfig(TypedDict):
+    """Configuration that defines what actions are allowed for a human interrupt.
+
+    This controls the available interaction options when the graph is paused for human input.
+    """
+
+    allow_accept: NotRequired[bool]
+    """Whether the human can approve the current action without changes."""
+    allow_edit: NotRequired[bool]
+    """Whether the human can approve the current action with edited content."""
+    allow_respond: NotRequired[bool]
+    """Whether the human can reject the current action with feedback."""
+
+
+class ActionRequest(TypedDict):
+    """Represents a request with a name and arguments."""
+
+    action: str
+    """The type or name of action being requested (e.g., "add_numbers")."""
+    args: dict
+    """Key-value pairs of arguments needed for the action (e.g., {"a": 1, "b": 2})."""
+
+
+class HumanInTheLoopRequest(TypedDict):
+    """Represents an interrupt triggered by the graph that requires human intervention.
+
+    Example:
+        ```python
+        # Extract a tool call from the state and create an interrupt request
+        request = HumanInterrupt(
+            action_request=ActionRequest(
+                action="run_command",  # The action being requested
+                args={"command": "ls", "args": ["-l"]},  # Arguments for the action
+            ),
+            config=HumanInTheLoopConfig(
+                allow_accept=True,  # Allow approval
+                allow_respond=True,  # Allow rejection with feedback
+                allow_edit=False,  # Don't allow approval with edits
+            ),
+            description="Please review the command before execution",
+        )
+        # Send the interrupt request and get the response
+        response = interrupt([request])[0]
+        ```
+    """
+
+    action_request: ActionRequest
+    """The specific action being requested from the human."""
+    config: HumanInTheLoopConfig
+    """Configuration defining what response types are allowed."""
+    description: str | None
+    """Optional detailed description of what input is needed."""
+
+
+class AcceptPayload(TypedDict):
+    """Response when a human approves the action."""
+
+    type: Literal["accept"]
+    """The type of response when a human approves the action."""
+
+
+class ResponsePayload(TypedDict):
+    """Response when a human rejects the action."""
+
+    type: Literal["response"]
+    """The type of response when a human rejects the action."""
+
+    args: NotRequired[str]
+    """The message to be sent to the model explaining why the action was rejected."""
+
+
+class EditPayload(TypedDict):
+    """Response when a human edits the action."""
+
+    type: Literal["edit"]
+    """The type of response when a human edits the action."""
+
+    args: ActionRequest
+    """The action request with the edited content."""
+
+
+HumanInTheLoopResponse = AcceptPayload | ResponsePayload | EditPayload
+"""Aggregated response type for all possible human in the loop responses."""
+
+
+class ToolConfig(TypedDict):
+    """Configuration for a tool requiring human in the loop."""
+
+    allow_accept: NotRequired[bool]
+    """Whether the human can approve the current action without changes."""
+    allow_edit: NotRequired[bool]
+    """Whether the human can approve the current action with edited content."""
+    allow_respond: NotRequired[bool]
+    """Whether the human can reject the current action with feedback."""
+    description: NotRequired[str]
+    """The description attached to the request for human input."""
 
 
 class HumanInTheLoopMiddleware(AgentMiddleware):
@@ -21,18 +112,36 @@ class HumanInTheLoopMiddleware(AgentMiddleware):
 
     def __init__(
         self,
-        tool_configs: ToolInterruptConfig,
-        message_prefix: str = "Tool execution requires approval",
+        tool_configs: dict[str, bool | ToolConfig],
+        *,
+        description_prefix: str = "Tool execution requires approval",
     ) -> None:
         """Initialize the human in the loop middleware.
 
         Args:
-            tool_configs: The tool interrupt configs to use for the middleware.
-            message_prefix: The message prefix to use when constructing interrupt content.
+            tool_configs: Mapping of tool name to allowed actions.
+                If a tool doesn't have an entry, it's auto-approved by default.
+                * `True` indicates all actions are allowed: accept, edit, and respond.
+                * `False` indicates that the tool is auto-approved.
+                * ToolConfig indicates the specific actions allowed for this tool.
+            description_prefix: The prefix to use when constructing action requests.
+                This is used to provide context about the tool call and the action being requested.
+                Not used if a tool has a description in its ToolConfig.
         """
         super().__init__()
-        self.tool_configs = tool_configs
-        self.message_prefix = message_prefix
+        resolved_tool_configs: dict[str, ToolConfig] = {}
+        for tool_name, tool_config in tool_configs.items():
+            if isinstance(tool_config, bool):
+                if tool_config is True:
+                    resolved_tool_configs[tool_name] = ToolConfig(
+                        allow_accept=True,
+                        allow_edit=True,
+                        allow_respond=True,
+                    )
+            else:
+                resolved_tool_configs[tool_name] = tool_config
+        self.tool_configs = resolved_tool_configs
+        self.description_prefix = description_prefix
 
     def after_model(self, state: AgentState) -> dict[str, Any] | None:
         """Trigger HITL flows for relevant tool calls after an AIMessage."""
@@ -40,96 +149,105 @@ class HumanInTheLoopMiddleware(AgentMiddleware):
         if not messages:
             return None
 
-        last_message = messages[-1]
-
-        if not hasattr(last_message, "tool_calls") or not last_message.tool_calls:
+        last_ai_msg = next((msg for msg in messages if isinstance(msg, AIMessage)), None)
+        if not last_ai_msg or not last_ai_msg.tool_calls:
             return None
 
         # Separate tool calls that need interrupts from those that don't
-        interrupt_tool_calls = []
+        hitl_tool_calls: list[ToolCall] = []
         auto_approved_tool_calls = []
 
-        for tool_call in last_message.tool_calls:
-            tool_name = tool_call["name"]
-            if tool_name in self.tool_configs:
-                interrupt_tool_calls.append(tool_call)
-            else:
-                auto_approved_tool_calls.append(tool_call)
+        for tool_call in last_ai_msg.tool_calls:
+            hitl_tool_calls.append(tool_call) if tool_call[
+                "name"
+            ] in self.tool_configs else auto_approved_tool_calls.append(tool_call)
 
         # If no interrupts needed, return early
-        if not interrupt_tool_calls:
+        if not hitl_tool_calls:
             return None
 
-        approved_tool_calls = auto_approved_tool_calls.copy()
+        # Process all tool calls that require interrupts
+        approved_tool_calls: list[ToolCall] = auto_approved_tool_calls.copy()
+        artificial_tool_messages: list[ToolMessage] = []
 
-        # Right now, we do not support multiple tool calls with interrupts
-        if len(interrupt_tool_calls) > 1:
-            tool_names = [t["name"] for t in interrupt_tool_calls]
-            msg = (
-                f"Called the following tools which require interrupts: {tool_names}\n\n"
-                "You may only call ONE tool that requires an interrupt at a time"
+        # Create interrupt requests for all tools that need approval
+        hitl_requests: list[HumanInTheLoopRequest] = []
+        for tool_call in hitl_tool_calls:
+            tool_name = tool_call["name"]
+            tool_args = tool_call["args"]
+            config = self.tool_configs[tool_name]
+            description = (
+                config.get("description")
+                or f"{self.description_prefix}\n\nTool: {tool_name}\nArgs: {tool_args}"
             )
-            return {
-                "messages": _generate_correction_tool_messages(msg, last_message.tool_calls),
-                "jump_to": "model",
-            }
 
-        # Right now, we do not support interrupting a tool call if other tool calls exist
-        if auto_approved_tool_calls:
-            tool_names = [t["name"] for t in interrupt_tool_calls]
+            request: HumanInTheLoopRequest = {
+                "action_request": ActionRequest(
+                    action=tool_name,
+                    args=tool_args,
+                ),
+                "config": config,
+                "description": description,
+            }
+            hitl_requests.append(request)
+
+        responses: list[HumanInTheLoopResponse] = interrupt(hitl_requests)
+
+        # Validate that the number of responses matches the number of interrupt tool calls
+        if (responses_len := len(responses)) != (hitl_tool_calls_len := len(hitl_tool_calls)):
             msg = (
-                f"Called the following tools which require interrupts: {tool_names}. "
-                "You also called other tools that do not require interrupts. "
-                "If you call a tool that requires and interrupt, you may ONLY call that tool."
+                f"Number of human responses ({responses_len}) does not match "
+                f"number of hanging tool calls ({hitl_tool_calls_len})."
             )
-            return {
-                "messages": _generate_correction_tool_messages(msg, last_message.tool_calls),
-                "jump_to": "model",
-            }
-
-        # Only one tool call will need interrupts
-        tool_call = interrupt_tool_calls[0]
-        tool_name = tool_call["name"]
-        tool_args = tool_call["args"]
-        description = f"{self.message_prefix}\n\nTool: {tool_name}\nArgs: {tool_args}"
-        tool_config = self.tool_configs[tool_name]
-
-        request: HumanInterrupt = {
-            "action_request": ActionRequest(
-                action=tool_name,
-                args=tool_args,
-            ),
-            "config": tool_config,
-            "description": description,
-        }
-
-        responses: list[HumanResponse] = interrupt([request])
-        response = responses[0]
-
-        if response["type"] == "accept":
-            approved_tool_calls.append(tool_call)
-        elif response["type"] == "edit":
-            edited: ActionRequest = response["args"]  # type: ignore[assignment]
-            new_tool_call = {
-                "type": "tool_call",
-                "name": tool_call["name"],
-                "args": edited["args"],
-                "id": tool_call["id"],
-            }
-            approved_tool_calls.append(new_tool_call)
-        elif response["type"] == "ignore":
-            return {"jump_to": "__end__"}
-        elif response["type"] == "response":
-            tool_message = {
-                "role": "tool",
-                "tool_call_id": tool_call["id"],
-                "content": response["args"],
-            }
-            return {"messages": [tool_message], "jump_to": "model"}
-        else:
-            msg = f"Unknown response type: {response['type']}"
             raise ValueError(msg)
 
-        last_message.tool_calls = approved_tool_calls
+        for i, response in enumerate(responses):
+            tool_call = hitl_tool_calls[i]
+            config = self.tool_configs[tool_call["name"]]
 
-        return {"messages": [last_message]}
+            if response["type"] == "accept" and config.get("allow_accept"):
+                approved_tool_calls.append(tool_call)
+            elif response["type"] == "edit" and config.get("allow_edit"):
+                edited_action = response["args"]
+                approved_tool_calls.append(
+                    ToolCall(
+                        type="tool_call",
+                        name=edited_action["action"],
+                        args=edited_action["args"],
+                        id=tool_call["id"],
+                    )
+                )
+            elif response["type"] == "response" and config.get("allow_respond"):
+                # Create a tool message with the human's text response
+                content = response.get("args") or (
+                    f"User rejected the tool call for `{tool_call['name']}` "
+                    f"with id {tool_call['id']}"
+                )
+                tool_message = ToolMessage(
+                    content=content,
+                    name=tool_call["name"],
+                    tool_call_id=tool_call["id"],
+                    status="error",
+                )
+                artificial_tool_messages.append(tool_message)
+            else:
+                allowed_actions = [
+                    action
+                    for action in ["accept", "edit", "response"]
+                    if config.get(f"allow_{'respond' if action == 'response' else action}")
+                ]
+                msg = (
+                    f"Unexpected human response: {response}. "
+                    f"Response action '{response.get('type')}' "
+                    f"is not allowed for tool '{tool_call['name']}'. "
+                    f"Expected one of {allowed_actions} based on the tool's configuration."
+                )
+                raise ValueError(msg)
+
+        # Update the AI message to only include approved tool calls
+        last_ai_msg.tool_calls = approved_tool_calls
+
+        if len(approved_tool_calls) > 0:
+            return {"messages": [last_ai_msg, *artificial_tool_messages]}
+
+        return {"jump_to": "model", "messages": artificial_tool_messages}

libs/langchain_v1/langchain/agents/middleware_agent.py

@@ -2,14 +2,15 @@
 
 import itertools
 from collections.abc import Callable, Sequence
-from typing import Any
+from typing import Any, cast
 
 from langchain_core.language_models.chat_models import BaseChatModel
-from langchain_core.messages import AIMessage, SystemMessage, ToolMessage
+from langchain_core.messages import AIMessage, AnyMessage, SystemMessage, ToolMessage
 from langchain_core.runnables import Runnable
 from langchain_core.tools import BaseTool
 from langgraph.constants import END, START
 from langgraph.graph.state import StateGraph
+from langgraph.types import Send
 from langgraph.typing import ContextT
 from typing_extensions import TypedDict, TypeVar
 
@@ -211,15 +212,13 @@ def create_agent(  # noqa: PLR0915
         context_schema=context_schema,
     )
 
-    def _handle_model_output(state: dict[str, Any], output: AIMessage) -> dict[str, Any]:
+    def _handle_model_output(output: AIMessage) -> dict[str, Any]:
         """Handle model output including structured responses."""
         # Handle structured output with native strategy
         if isinstance(response_format, ProviderStrategy):
             if not output.tool_calls and native_output_binding:
                 structured_response = native_output_binding.parse(output)
                 return {"messages": [output], "response": structured_response}
-            if state.get("response") is not None:
-                return {"messages": [output], "response": None}
             return {"messages": [output]}
 
         # Handle structured output with tools strategy
@@ -297,9 +296,6 @@ def create_agent(  # noqa: PLR0915
                         ],
                     }
 
-        # Standard response handling
-        if state.get("response") is not None:
-            return {"messages": [output], "response": None}
         return {"messages": [output]}
 
     def _get_bound_model(request: ModelRequest) -> Runnable:
@@ -346,7 +342,7 @@ def create_agent(  # noqa: PLR0915
             messages = [SystemMessage(request.system_prompt), *messages]
 
         output = model_.invoke(messages)
-        return _handle_model_output(state, output)
+        return _handle_model_output(output)
 
     async def amodel_request(state: dict[str, Any]) -> dict[str, Any]:
         """Async model request handler with sequential middleware processing."""
@@ -373,7 +369,7 @@ def create_agent(  # noqa: PLR0915
             messages = [SystemMessage(request.system_prompt), *messages]
 
         output = await model_.ainvoke(messages)
-        return _handle_model_output(state, output)
+        return _handle_model_output(output)
 
     # Use sync or async based on model capabilities
     from langgraph._internal._runnable import RunnableCallable
@@ -417,12 +413,12 @@ def create_agent(  # noqa: PLR0915
     if tool_node is not None:
         graph.add_conditional_edges(
             "tools",
-            _make_tools_to_model_edge(tool_node, first_node),
+            _make_tools_to_model_edge(tool_node, first_node, structured_output_tools),
             [first_node, END],
         )
         graph.add_conditional_edges(
             last_node,
-            _make_model_to_tools_edge(first_node, structured_output_tools),
+            _make_model_to_tools_edge(first_node, structured_output_tools, tool_node),
             [first_node, "tools", END],
         )
     elif last_node == "model_request":
@@ -481,27 +477,48 @@ def _resolve_jump(jump_to: JumpTo | None, first_node: str) -> str | None:
     return None
 
 
+def _fetch_last_ai_and_tool_messages(
+    messages: list[AnyMessage],
+) -> tuple[AIMessage, list[ToolMessage]]:
+    last_ai_index: int
+    last_ai_message: AIMessage
+
+    for i in range(len(messages) - 1, -1, -1):
+        if isinstance(messages[i], AIMessage):
+            last_ai_index = i
+            last_ai_message = cast("AIMessage", messages[i])
+            break
+
+    tool_messages = [m for m in messages[last_ai_index + 1 :] if isinstance(m, ToolMessage)]
+    return last_ai_message, tool_messages
+
+
 def _make_model_to_tools_edge(
-    first_node: str, structured_output_tools: dict[str, OutputToolBinding]
-) -> Callable[[AgentState], str | None]:
-    def model_to_tools(state: AgentState) -> str | None:
+    first_node: str, structured_output_tools: dict[str, OutputToolBinding], tool_node: ToolNode
+) -> Callable[[AgentState], str | list[Send] | None]:
+    def model_to_tools(state: AgentState) -> str | list[Send] | None:
         if jump_to := state.get("jump_to"):
             return _resolve_jump(jump_to, first_node)
 
-        message = state["messages"][-1]
+        last_ai_message, tool_messages = _fetch_last_ai_and_tool_messages(state["messages"])
+        tool_message_ids = [m.tool_call_id for m in tool_messages]
 
-        # Check if this is a ToolMessage from structured output - if so, end
-        if isinstance(message, ToolMessage) and message.name in structured_output_tools:
-            return END
+        pending_tool_calls = [
+            c
+            for c in last_ai_message.tool_calls
+            if c["id"] not in tool_message_ids and c["name"] not in structured_output_tools
+        ]
 
-        # Check for tool calls
-        if isinstance(message, AIMessage) and message.tool_calls:
-            # If all tool calls are for structured output, don't go to tools
-            non_structured_calls = [
-                tc for tc in message.tool_calls if tc["name"] not in structured_output_tools
+        if pending_tool_calls:
+            # imo we should not be injecting state, store here,
+            # this should be done by the tool node itself ideally but this is a consequence
+            # of using Send w/ tool calls directly which allows more intuitive interrupt behavior
+            # largely internal so can be fixed later
+            pending_tool_calls = [
+                tool_node.inject_tool_args(call, state, None)  # type: ignore[arg-type]
+                for call in pending_tool_calls
             ]
-            if non_structured_calls:
-                return "tools"
+            return [Send("tools", [tool_call]) for tool_call in pending_tool_calls]
 
         return END
 
@@ -509,17 +526,21 @@ def _make_model_to_tools_edge(
 
 
 def _make_tools_to_model_edge(
-    tool_node: ToolNode, next_node: str
+    tool_node: ToolNode, next_node: str, structured_output_tools: dict[str, OutputToolBinding]
 ) -> Callable[[AgentState], str | None]:
     def tools_to_model(state: AgentState) -> str | None:
-        ai_message = [m for m in state["messages"] if isinstance(m, AIMessage)][-1]
+        last_ai_message, tool_messages = _fetch_last_ai_and_tool_messages(state["messages"])
+
         if all(
             tool_node.tools_by_name[c["name"]].return_direct
-            for c in ai_message.tool_calls
+            for c in last_ai_message.tool_calls
             if c["name"] in tool_node.tools_by_name
         ):
             return END
 
+        if any(t.name in structured_output_tools for t in tool_messages):
+            return END
+
         return next_node
 
     return tools_to_model

libs/langchain_v1/tests/unit_tests/agents/test_middleware_agent.py

@@ -4,6 +4,7 @@ from unittest.mock import patch
 
 from syrupy.assertion import SnapshotAssertion
 
+from pydantic import BaseModel, Field
 from langchain_core.language_models import BaseChatModel
 from langchain_core.language_models.chat_models import BaseChatModel
 from langchain_core.messages import (
@@ -14,19 +15,23 @@ from langchain_core.messages import (
     ToolMessage,
 )
 from langchain_core.tools import tool
+from langgraph.types import Command
 
 from langchain.agents.middleware_agent import create_agent
-from langchain.agents.middleware.human_in_the_loop import HumanInTheLoopMiddleware
+from langchain.agents.middleware.human_in_the_loop import (
+    HumanInTheLoopMiddleware,
+    HumanInTheLoopConfig,
+    ActionRequest,
+)
 from langchain.agents.middleware.prompt_caching import AnthropicPromptCachingMiddleware
 from langchain.agents.middleware.summarization import SummarizationMiddleware
 from langchain.agents.middleware.types import AgentMiddleware, ModelRequest, AgentState
-from langchain_core.tools import BaseTool
 
 from langgraph.checkpoint.base import BaseCheckpointSaver
 from langgraph.checkpoint.memory import InMemorySaver
 from langgraph.constants import END
 from langgraph.graph.message import REMOVE_ALL_MESSAGES
-from langgraph.prebuilt.interrupt import ActionRequest, HumanInterruptConfig
+from langchain.agents.structured_output import ToolStrategy
 
 from .messages import _AnyIdHumanMessage, _AnyIdToolMessage
 from .model import FakeToolCallingModel
@@ -355,27 +360,28 @@ def test_create_agent_jump(
 # Tests for HumanInTheLoopMiddleware
 def test_human_in_the_loop_middleware_initialization() -> None:
     """Test HumanInTheLoopMiddleware initialization."""
-    tool_configs = {
-        "test_tool": HumanInterruptConfig(
-            allow_ignore=True, allow_respond=True, allow_edit=True, allow_accept=True
-        )
+
+    middleware = HumanInTheLoopMiddleware(
+        tool_configs={
+            "test_tool": {"allow_accept": True, "allow_edit": True, "allow_respond": True}
+        },
+        description_prefix="Custom prefix",
+    )
+
+    assert middleware.tool_configs == {
+        "test_tool": {"allow_accept": True, "allow_edit": True, "allow_respond": True}
     }
-
-    middleware = HumanInTheLoopMiddleware(tool_configs=tool_configs, message_prefix="Custom prefix")
-
-    assert middleware.tool_configs == tool_configs
-    assert middleware.message_prefix == "Custom prefix"
+    assert middleware.description_prefix == "Custom prefix"
 
 
 def test_human_in_the_loop_middleware_no_interrupts_needed() -> None:
     """Test HumanInTheLoopMiddleware when no interrupts are needed."""
-    tool_configs = {
-        "test_tool": HumanInterruptConfig(
-            allow_ignore=True, allow_respond=True, allow_edit=True, allow_accept=True
-        )
-    }
 
-    middleware = HumanInTheLoopMiddleware(tool_configs=tool_configs)
+    middleware = HumanInTheLoopMiddleware(
+        tool_configs={
+            "test_tool": {"allow_respond": True, "allow_edit": True, "allow_accept": True}
+        }
+    )
 
     # Test with no messages
     state: dict[str, Any] = {"messages": []}
@@ -397,15 +403,14 @@ def test_human_in_the_loop_middleware_no_interrupts_needed() -> None:
     assert result is None
 
 
-def test_human_in_the_loop_middleware_interrupt_responses() -> None:
-    """Test HumanInTheLoopMiddleware with different interrupt response types."""
-    tool_configs = {
-        "test_tool": HumanInterruptConfig(
-            allow_ignore=True, allow_respond=True, allow_edit=True, allow_accept=True
-        )
-    }
+def test_human_in_the_loop_middleware_single_tool_accept() -> None:
+    """Test HumanInTheLoopMiddleware with single tool accept response."""
 
-    middleware = HumanInTheLoopMiddleware(tool_configs=tool_configs)
+    middleware = HumanInTheLoopMiddleware(
+        tool_configs={
+            "test_tool": {"allow_respond": True, "allow_edit": True, "allow_accept": True}
+        }
+    )
 
     ai_message = AIMessage(
         content="I'll help you",
@@ -413,55 +418,443 @@ def test_human_in_the_loop_middleware_interrupt_responses() -> None:
     )
     state = {"messages": [HumanMessage(content="Hello"), ai_message]}
 
-    # Test accept response
     def mock_accept(requests):
         return [{"type": "accept", "args": None}]
 
     with patch("langchain.agents.middleware.human_in_the_loop.interrupt", side_effect=mock_accept):
         result = middleware.after_model(state)
         assert result is not None
+        assert "messages" in result
+        assert len(result["messages"]) == 1
         assert result["messages"][0] == ai_message
         assert result["messages"][0].tool_calls == ai_message.tool_calls
 
-    # Test edit response
+
+def test_human_in_the_loop_middleware_single_tool_edit() -> None:
+    """Test HumanInTheLoopMiddleware with single tool edit response."""
+    middleware = HumanInTheLoopMiddleware(
+        tool_configs={
+            "test_tool": {"allow_respond": True, "allow_edit": True, "allow_accept": True}
+        }
+    )
+
+    ai_message = AIMessage(
+        content="I'll help you",
+        tool_calls=[{"name": "test_tool", "args": {"input": "test"}, "id": "1"}],
+    )
+    state = {"messages": [HumanMessage(content="Hello"), ai_message]}
+
     def mock_edit(requests):
         return [
-            {"type": "edit", "args": ActionRequest(action="test_tool", args={"input": "edited"})}
+            {
+                "type": "edit",
+                "args": ActionRequest(
+                    action="test_tool",
+                    args={"input": "edited"},
+                ),
+            }
         ]
 
     with patch("langchain.agents.middleware.human_in_the_loop.interrupt", side_effect=mock_edit):
         result = middleware.after_model(state)
         assert result is not None
+        assert "messages" in result
+        assert len(result["messages"]) == 1
         assert result["messages"][0].tool_calls[0]["args"] == {"input": "edited"}
+        assert result["messages"][0].tool_calls[0]["id"] == "1"  # ID should be preserved
 
-    # Test ignore response
-    def mock_ignore(requests):
-        return [{"type": "ignore", "args": None}]
 
-    with patch("langchain.agents.middleware.human_in_the_loop.interrupt", side_effect=mock_ignore):
-        result = middleware.after_model(state)
-        assert result is not None
-        assert result["jump_to"] == "__end__"
+def test_human_in_the_loop_middleware_single_tool_response() -> None:
+    """Test HumanInTheLoopMiddleware with single tool response with custom message."""
+
+    middleware = HumanInTheLoopMiddleware(
+        tool_configs={
+            "test_tool": {"allow_respond": True, "allow_edit": True, "allow_accept": True}
+        }
+    )
+
+    ai_message = AIMessage(
+        content="I'll help you",
+        tool_calls=[{"name": "test_tool", "args": {"input": "test"}, "id": "1"}],
+    )
+    state = {"messages": [HumanMessage(content="Hello"), ai_message]}
 
-    # Test response type
     def mock_response(requests):
-        return [{"type": "response", "args": "Custom response"}]
+        return [{"type": "response", "args": "Custom response message"}]
 
     with patch(
         "langchain.agents.middleware.human_in_the_loop.interrupt", side_effect=mock_response
     ):
         result = middleware.after_model(state)
         assert result is not None
-        assert result["jump_to"] == "model"
-        assert result["messages"][0]["role"] == "tool"
-        assert result["messages"][0]["content"] == "Custom response"
+        assert "messages" in result
+        assert len(result["messages"]) == 1  # Only tool message when no approved tool calls
+        assert isinstance(result["messages"][0], ToolMessage)
+        assert result["messages"][0].content == "Custom response message"
+        assert result["messages"][0].name == "test_tool"
+        assert result["messages"][0].tool_call_id == "1"
+
+
+def test_human_in_the_loop_middleware_multiple_tools_mixed_responses() -> None:
+    """Test HumanInTheLoopMiddleware with multiple tools and mixed response types."""
+
+    middleware = HumanInTheLoopMiddleware(
+        tool_configs={
+            "get_forecast": {"allow_accept": True, "allow_edit": True, "allow_respond": True},
+            "get_temperature": {"allow_accept": True, "allow_edit": True, "allow_respond": True},
+        }
+    )
+
+    ai_message = AIMessage(
+        content="I'll help you with weather",
+        tool_calls=[
+            {"name": "get_forecast", "args": {"location": "San Francisco"}, "id": "1"},
+            {"name": "get_temperature", "args": {"location": "San Francisco"}, "id": "2"},
+        ],
+    )
+    state = {"messages": [HumanMessage(content="What's the weather?"), ai_message]}
+
+    def mock_mixed_responses(requests):
+        return [
+            {"type": "accept", "args": None},
+            {"type": "response", "args": "User rejected this tool call"},
+        ]
+
+    with patch(
+        "langchain.agents.middleware.human_in_the_loop.interrupt", side_effect=mock_mixed_responses
+    ):
+        result = middleware.after_model(state)
+        assert result is not None
+        assert "messages" in result
+        assert (
+            len(result["messages"]) == 2
+        )  # AI message with accepted tool call + tool message for rejected
+
+        # First message should be the AI message with updated tool calls
+        updated_ai_message = result["messages"][0]
+        assert len(updated_ai_message.tool_calls) == 1  # Only accepted tool call
+        assert updated_ai_message.tool_calls[0]["name"] == "get_forecast"  # Accepted
+
+        # Second message should be the tool message for the rejected tool call
+        tool_message = result["messages"][1]
+        assert isinstance(tool_message, ToolMessage)
+        assert tool_message.content == "User rejected this tool call"
+        assert tool_message.name == "get_temperature"
+
+
+def test_human_in_the_loop_middleware_multiple_tools_edit_responses() -> None:
+    """Test HumanInTheLoopMiddleware with multiple tools and edit responses."""
+
+    middleware = HumanInTheLoopMiddleware(
+        tool_configs={
+            "get_forecast": {"allow_accept": True, "allow_edit": True, "allow_respond": True},
+            "get_temperature": {"allow_accept": True, "allow_edit": True, "allow_respond": True},
+        }
+    )
+
+    ai_message = AIMessage(
+        content="I'll help you with weather",
+        tool_calls=[
+            {"name": "get_forecast", "args": {"location": "San Francisco"}, "id": "1"},
+            {"name": "get_temperature", "args": {"location": "San Francisco"}, "id": "2"},
+        ],
+    )
+    state = {"messages": [HumanMessage(content="What's the weather?"), ai_message]}
+
+    def mock_edit_responses(requests):
+        return [
+            {
+                "type": "edit",
+                "args": ActionRequest(
+                    action="get_forecast",
+                    args={"location": "New York"},
+                ),
+            },
+            {
+                "type": "edit",
+                "args": ActionRequest(
+                    action="get_temperature",
+                    args={"location": "New York"},
+                ),
+            },
+        ]
+
+    with patch(
+        "langchain.agents.middleware.human_in_the_loop.interrupt", side_effect=mock_edit_responses
+    ):
+        result = middleware.after_model(state)
+        assert result is not None
+        assert "messages" in result
+        assert len(result["messages"]) == 1
+
+        updated_ai_message = result["messages"][0]
+        assert updated_ai_message.tool_calls[0]["args"] == {"location": "New York"}
+        assert updated_ai_message.tool_calls[0]["id"] == "1"  # ID preserved
+        assert updated_ai_message.tool_calls[1]["args"] == {"location": "New York"}
+        assert updated_ai_message.tool_calls[1]["id"] == "2"  # ID preserved
+
+
+def test_human_in_the_loop_middleware_edit_with_modified_args() -> None:
+    """Test HumanInTheLoopMiddleware with edit action that includes modified args."""
+
+    middleware = HumanInTheLoopMiddleware(
+        tool_configs={
+            "test_tool": {"allow_accept": True, "allow_edit": True, "allow_respond": True}
+        }
+    )
+
+    ai_message = AIMessage(
+        content="I'll help you",
+        tool_calls=[{"name": "test_tool", "args": {"input": "test"}, "id": "1"}],
+    )
+    state = {"messages": [HumanMessage(content="Hello"), ai_message]}
+
+    def mock_edit_with_args(requests):
+        return [
+            {
+                "type": "edit",
+                "args": ActionRequest(
+                    action="test_tool",
+                    args={"input": "modified"},
+                ),
+            }
+        ]
+
+    with patch(
+        "langchain.agents.middleware.human_in_the_loop.interrupt",
+        side_effect=mock_edit_with_args,
+    ):
+        result = middleware.after_model(state)
+        assert result is not None
+        assert "messages" in result
+        assert len(result["messages"]) == 1
+
+        # Should have modified args
+        updated_ai_message = result["messages"][0]
+        assert updated_ai_message.tool_calls[0]["args"] == {"input": "modified"}
+        assert updated_ai_message.tool_calls[0]["id"] == "1"  # ID preserved
+
+
+def test_human_in_the_loop_middleware_unknown_response_type() -> None:
+    """Test HumanInTheLoopMiddleware with unknown response type."""
+    middleware = HumanInTheLoopMiddleware(
+        tool_configs={
+            "test_tool": {"allow_accept": True, "allow_edit": True, "allow_respond": True}
+        }
+    )
+
+    ai_message = AIMessage(
+        content="I'll help you",
+        tool_calls=[{"name": "test_tool", "args": {"input": "test"}, "id": "1"}],
+    )
+    state = {"messages": [HumanMessage(content="Hello"), ai_message]}
 
-    # Test unknown response type
     def mock_unknown(requests):
         return [{"type": "unknown", "args": None}]
 
     with patch("langchain.agents.middleware.human_in_the_loop.interrupt", side_effect=mock_unknown):
-        with pytest.raises(ValueError, match="Unknown response type: unknown"):
+        with pytest.raises(
+            ValueError,
+            match=r"Unexpected human response: {'type': 'unknown', 'args': None}. Response action 'unknown' is not allowed for tool 'test_tool'. Expected one of \['accept', 'edit', 'response'\] based on the tool's configuration.",
+        ):
+            middleware.after_model(state)
+
+
+def test_human_in_the_loop_middleware_disallowed_action() -> None:
+    """Test HumanInTheLoopMiddleware with action not allowed by tool config."""
+
+    # edit is not allowed by tool config
+    middleware = HumanInTheLoopMiddleware(
+        tool_configs={
+            "test_tool": {"allow_respond": True, "allow_edit": False, "allow_accept": True}
+        }
+    )
+
+    ai_message = AIMessage(
+        content="I'll help you",
+        tool_calls=[{"name": "test_tool", "args": {"input": "test"}, "id": "1"}],
+    )
+    state = {"messages": [HumanMessage(content="Hello"), ai_message]}
+
+    def mock_disallowed_action(requests):
+        return [
+            {
+                "type": "edit",
+                "args": ActionRequest(
+                    action="test_tool",
+                    args={"input": "modified"},
+                ),
+            }
+        ]
+
+    with patch(
+        "langchain.agents.middleware.human_in_the_loop.interrupt",
+        side_effect=mock_disallowed_action,
+    ):
+        with pytest.raises(
+            ValueError,
+            match=r"Unexpected human response: {'type': 'edit', 'args': {'action': 'test_tool', 'args': {'input': 'modified'}}}. Response action 'edit' is not allowed for tool 'test_tool'. Expected one of \['accept', 'response'\] based on the tool's configuration.",
+        ):
+            middleware.after_model(state)
+
+
+def test_human_in_the_loop_middleware_mixed_auto_approved_and_interrupt() -> None:
+    """Test HumanInTheLoopMiddleware with mix of auto-approved and interrupt tools."""
+
+    middleware = HumanInTheLoopMiddleware(
+        tool_configs={
+            "interrupt_tool": {"allow_respond": True, "allow_edit": True, "allow_accept": True}
+        }
+    )
+
+    ai_message = AIMessage(
+        content="I'll help you",
+        tool_calls=[
+            {"name": "auto_tool", "args": {"input": "auto"}, "id": "1"},
+            {"name": "interrupt_tool", "args": {"input": "interrupt"}, "id": "2"},
+        ],
+    )
+    state = {"messages": [HumanMessage(content="Hello"), ai_message]}
+
+    def mock_accept(requests):
+        return [{"type": "accept", "args": None}]
+
+    with patch("langchain.agents.middleware.human_in_the_loop.interrupt", side_effect=mock_accept):
+        result = middleware.after_model(state)
+        assert result is not None
+        assert "messages" in result
+        assert len(result["messages"]) == 1
+
+        updated_ai_message = result["messages"][0]
+        # Should have both tools: auto-approved first, then interrupt tool
+        assert len(updated_ai_message.tool_calls) == 2
+        assert updated_ai_message.tool_calls[0]["name"] == "auto_tool"
+        assert updated_ai_message.tool_calls[1]["name"] == "interrupt_tool"
+
+
+def test_human_in_the_loop_middleware_interrupt_request_structure() -> None:
+    """Test that interrupt requests are structured correctly."""
+
+    middleware = HumanInTheLoopMiddleware(
+        tool_configs={
+            "test_tool": {"allow_accept": True, "allow_edit": True, "allow_respond": True}
+        },
+        description_prefix="Custom prefix",
+    )
+
+    ai_message = AIMessage(
+        content="I'll help you",
+        tool_calls=[{"name": "test_tool", "args": {"input": "test", "location": "SF"}, "id": "1"}],
+    )
+    state = {"messages": [HumanMessage(content="Hello"), ai_message]}
+
+    captured_requests = []
+
+    def mock_capture_requests(requests):
+        captured_requests.extend(requests)
+        return [{"type": "accept", "args": None}]
+
+    with patch(
+        "langchain.agents.middleware.human_in_the_loop.interrupt", side_effect=mock_capture_requests
+    ):
+        middleware.after_model(state)
+
+        assert len(captured_requests) == 1
+        request = captured_requests[0]
+
+        assert "action_request" in request
+        assert "config" in request
+        assert "description" in request
+
+        assert request["action_request"]["action"] == "test_tool"
+        assert request["action_request"]["args"] == {"input": "test", "location": "SF"}
+        expected_config = {"allow_accept": True, "allow_edit": True, "allow_respond": True}
+        assert request["config"] == expected_config
+        assert "Custom prefix" in request["description"]
+        assert "Tool: test_tool" in request["description"]
+        assert "Args: {'input': 'test', 'location': 'SF'}" in request["description"]
+
+
+def test_human_in_the_loop_middleware_boolean_configs() -> None:
+    """Test HITL middleware with boolean tool configs."""
+    middleware = HumanInTheLoopMiddleware(tool_configs={"test_tool": True})
+
+    ai_message = AIMessage(
+        content="I'll help you",
+        tool_calls=[{"name": "test_tool", "args": {"input": "test"}, "id": "1"}],
+    )
+    state = {"messages": [HumanMessage(content="Hello"), ai_message]}
+
+    # Test accept
+    with patch(
+        "langchain.agents.middleware.human_in_the_loop.interrupt",
+        return_value=[{"type": "accept", "args": None}],
+    ):
+        result = middleware.after_model(state)
+        assert result is not None
+        assert "messages" in result
+        assert len(result["messages"]) == 1
+        assert result["messages"][0].tool_calls == ai_message.tool_calls
+
+    # Test edit
+    with patch(
+        "langchain.agents.middleware.human_in_the_loop.interrupt",
+        return_value=[
+            {
+                "type": "edit",
+                "args": ActionRequest(
+                    action="test_tool",
+                    args={"input": "edited"},
+                ),
+            }
+        ],
+    ):
+        result = middleware.after_model(state)
+        assert result is not None
+        assert "messages" in result
+        assert len(result["messages"]) == 1
+        assert result["messages"][0].tool_calls[0]["args"] == {"input": "edited"}
+
+    middleware = HumanInTheLoopMiddleware(tool_configs={"test_tool": False})
+
+    result = middleware.after_model(state)
+    # No interruption should occur
+    assert result is None
+
+
+def test_human_in_the_loop_middleware_sequence_mismatch() -> None:
+    """Test that sequence mismatch in resume raises an error."""
+    middleware = HumanInTheLoopMiddleware(tool_configs={"test_tool": True})
+
+    ai_message = AIMessage(
+        content="I'll help you",
+        tool_calls=[{"name": "test_tool", "args": {"input": "test"}, "id": "1"}],
+    )
+    state = {"messages": [HumanMessage(content="Hello"), ai_message]}
+
+    # Test with too few responses
+    with patch(
+        "langchain.agents.middleware.human_in_the_loop.interrupt",
+        return_value=[],  # No responses for 1 tool call
+    ):
+        with pytest.raises(
+            ValueError,
+            match=r"Number of human responses \(0\) does not match number of hanging tool calls \(1\)\.",
+        ):
+            middleware.after_model(state)
+
+    # Test with too many responses
+    with patch(
+        "langchain.agents.middleware.human_in_the_loop.interrupt",
+        return_value=[
+            {"type": "accept", "args": None},
+            {"type": "accept", "args": None},
+        ],  # 2 responses for 1 tool call
+    ):
+        with pytest.raises(
+            ValueError,
+            match=r"Number of human responses \(2\) does not match number of hanging tool calls \(1\)\.",
+        ):
             middleware.after_model(state)
 
 
@@ -733,3 +1126,78 @@ def test_modify_model_request() -> None:
     assert (
         result["messages"][2].content == "You are a helpful assistant.-Hello-remember to be nice!"
     )
+
+
+def test_tools_to_model_edge_with_structured_and_regular_tool_calls():
+    """Test that when there are both structured and regular tool calls, we execute regular and jump to END."""
+
+    class WeatherResponse(BaseModel):
+        """Weather response."""
+
+        temperature: float = Field(description="Temperature in fahrenheit")
+        condition: str = Field(description="Weather condition")
+
+    @tool
+    def regular_tool(query: str) -> str:
+        """A regular tool that returns a string."""
+        return f"Regular tool result for: {query}"
+
+    # Create a fake model that returns both structured and regular tool calls
+    class FakeModelWithBothToolCalls(FakeToolCallingModel):
+        def __init__(self):
+            super().__init__()
+            self.tool_calls = [
+                [
+                    ToolCall(
+                        name="WeatherResponse",
+                        args={"temperature": 72.0, "condition": "sunny"},
+                        id="structured_call_1",
+                    ),
+                    ToolCall(
+                        name="regular_tool", args={"query": "test query"}, id="regular_call_1"
+                    ),
+                ]
+            ]
+
+    # Create agent with both structured output and regular tools
+    agent = create_agent(
+        model=FakeModelWithBothToolCalls(),
+        tools=[regular_tool],
+        response_format=ToolStrategy(schema=WeatherResponse),
+    )
+
+    # Compile and invoke the agent
+    compiled_agent = agent.compile()
+    result = compiled_agent.invoke(
+        {"messages": [HumanMessage("What's the weather and help me with a query?")]}
+    )
+
+    # Verify that we have the expected messages:
+    # 1. Human message
+    # 2. AI message with both tool calls
+    # 3. Tool message from structured tool call
+    # 4. Tool message from regular tool call
+
+    messages = result["messages"]
+    assert len(messages) >= 4
+
+    # Check that we have the AI message with both tool calls
+    ai_message = messages[1]
+    assert isinstance(ai_message, AIMessage)
+    assert len(ai_message.tool_calls) == 2
+
+    # Check that we have a tool message from the regular tool
+    tool_messages = [m for m in messages if isinstance(m, ToolMessage)]
+    assert len(tool_messages) >= 1
+
+    # The regular tool should have been executed
+    regular_tool_message = next((m for m in tool_messages if m.name == "regular_tool"), None)
+    assert regular_tool_message is not None
+    assert "Regular tool result for: test query" in regular_tool_message.content
+
+    # Verify that the structured response is available in the result
+    assert "response" in result
+    assert result["response"] is not None
+    assert hasattr(result["response"], "temperature")
+    assert result["response"].temperature == 72.0
+    assert result["response"].condition == "sunny"