Eugene Yurtsev c2435eeca5 chore(langchain_v1): update on_tool_call to regular callbacks (#33364) ...

Refactor tool call middleware from generator-based to handler-based
pattern

Simplifies on_tool_call middleware by replacing the complex generator
protocol with a straightforward handler pattern. Instead of yielding
requests and receiving results via .send(),
handlers now receive an execute callable that can be invoked multiple
times for retry logic.


Before vs. After

Before (Generator):
```python
class RetryMiddleware(AgentMiddleware):
    def on_tool_call(self, request, state, runtime):
        for attempt in range(3):
            response = yield request  # Yield request, receive result via .send()
            if is_valid(response) or attempt == 2:
                return  # Final result is last value sent to generator
```

After (Handler):

```python
class RetryMiddleware(AgentMiddleware):
    def on_tool_call(self, request, handler):
        for attempt in range(3):
            result = handler(request)  # Direct function call
            if is_valid(result):
                return result
        return result
```


Follow up after this PR:

* Rename the interceptor to wrap_tool_call
* Fix the async path for the ToolNode

2025-10-08 21:46:03 -04:00

..

__init__.py

…

test_imports.py

chore(langchain_v1): move tool node to tools namespace (#33132)

2025-09-26 15:23:57 -04:00

test_on_tool_call.py

chore(langchain_v1): update on_tool_call to regular callbacks (#33364)

2025-10-08 21:46:03 -04:00