The `@shielded` decorator in async callback managers was not preserving
context variables, breaking OpenTelemetry instrumentation and other
context-dependent functionality.
## Problem
When using async callbacks with the `@shielded` decorator (applied to
methods like `on_llm_end`, `on_chain_end`, etc.), context variables were
not being preserved across the shield boundary. This caused issues with:
- OpenTelemetry span context propagation
- Other instrumentation that relies on context variables
- Inconsistent context behavior between sync and async execution
The issue was reproducible with:
```python
from contextvars import copy_context
import asyncio
from langgraph.graph import StateGraph
# Sync case: context remains consistent
print("SYNC")
print(copy_context()) # Same object
graph.invoke({"result": "init"})
print(copy_context()) # Same object
# Async case: context was inconsistent (before fix)
print("ASYNC")
asyncio.run(graph.ainvoke({"result": "init"}))
print(copy_context()) # Different object than expected
```
## Root Cause
The original `shielded` decorator implementation:
```python
async def wrapped(*args: Any, **kwargs: Any) -> Any:
return await asyncio.shield(func(*args, **kwargs))
```
Used `asyncio.shield()` directly without preserving the current
execution context, causing context variables to be lost.
## Solution
Modified the `shielded` decorator to:
1. Capture the current context using `copy_context()`
2. Create a task with explicit context using `asyncio.create_task(coro,
context=ctx)` for Python 3.11+
3. Shield the context-aware task
4. Fallback to regular task creation for Python < 3.11
```python
async def wrapped(*args: Any, **kwargs: Any) -> Any:
# Capture the current context to preserve context variables
ctx = copy_context()
coro = func(*args, **kwargs)
try:
# Create a task with the captured context to preserve context variables
task = asyncio.create_task(coro, context=ctx)
return await asyncio.shield(task)
except TypeError:
# Python < 3.11 fallback
task = asyncio.create_task(coro)
return await asyncio.shield(task)
```
## Testing
- Added comprehensive test
`test_shielded_callback_context_preservation()` that validates context
variables are preserved across shielded callback boundaries
- Verified the fix resolves the original LangGraph context consistency
issue
- Confirmed all existing callback manager tests still pass
- Validated OpenTelemetry-like instrumentation scenarios work correctly
The fix is minimal, maintains backward compatibility, and ensures proper
context preservation for both modern Python versions and older ones.
Fixes#31398.
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---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: mdrxy <61371264+mdrxy@users.noreply.github.com>
Co-authored-by: Mason Daugherty <github@mdrxy.com>
Co-authored-by: Mason Daugherty <mason@langchain.dev>
# Description
This submission is a part of a school project from our team of 4
@EminGul @williamzhu54 @annay54 @donttouch22.
Our pull request fixes the issue with RunnableParallel scheme being
empty by returning the correct schema output when children runnable
input schemas use TypedDicts.
# Issue
Fixes#24326
# Dependencies
No extra dependencies required for this fix.
# Feedback
Any feedback and advice is gladly welcomed. Please feel free to let us
know what we can change or improve upon regarding this issue.
---------
Co-authored-by: Mason Daugherty <mason@langchain.dev>
Co-authored-by: Mason Daugherty <github@mdrxy.com>
- standardize on using model IDs, no more aliases - makes future
maintenance easier
- use latest models in docstrings to highlight support
- remove remaining sonnet 3-7 usage due to deprecation
Depends on #33751
* Fix detection of support of context in `asyncio.create_task`
* Fix: in Python 3.14 `asyncio.get_event_loop()` raises an exception if
there's no running loop
* Bump pydantic to version 2.12
* Skips tests with pydantic v1 models as they are not supported with
Python 3.14
* Run core tests with Python 3.14 in CI.
---------
Co-authored-by: Mason Daugherty <mason@langchain.dev>
Co-authored-by: Sydney Runkle <54324534+sydney-runkle@users.noreply.github.com>
