fix(langchain): add types to human_in_the_loop middleware (#34137)
The `HumanInTheLoopMiddleware` is missing a type annotation for the
context schema. Without the fix in this PR, the following code does not
type check:
```
graph = create_agent(
"gpt-5",
tools=[send_email_tool, read_email_tool],
middleware=[
HumanInTheLoopMiddleware(
interrupt_on={
# Require approval or rejection for sending emails
"send_email_tool": {
"allowed_decisions": ["approve", "reject"],
},
# Auto-approve reading emails
"read_email_tool": False,
}
),
],
context_schema=ContextSchema,
)
```
```
Argument of type "list[HumanInTheLoopMiddleware]" cannot be assigned to parameter "middleware" of type "Sequence[AgentMiddleware[StateT_co@create_agent, ContextT@create_agent]]" in function "create_agent"
"HumanInTheLoopMiddleware" is not assignable to "AgentMiddleware[AgentState[Unknown], ContextSchema | None]"
Type parameter "ContextT@AgentMiddleware" is invariant, but "None" is not the same as "ContextSchema | None"
```
langchain
4065106c - fix(langchain): add types to human_in_the_loop middleware (#34137)
