fix(langchain): handle ToolNode in create_agent_wrapper tool extraction

[RRocaP]

Summary

Fixes #3921

Problem

When langgraph-supervisor's create_supervisor() passes a ToolNode
object to create_react_agent, the instrumentation crashes:

File "patch.py", line 489, in wrapper
    for tool in tools:
TypeError: 'ToolNode' object is not iterable

ToolNode wraps tools but does not implement __iter__. It exposes
tools via tools_by_name (a dict[str, BaseTool]).

Fix

Before iterating, check if the tools object has a tools_by_name
attribute. If so, iterate over its .values(). Otherwise, iterate
normally (preserving existing behavior for lists/tuples).

Files changed

• packages/opentelemetry-instrumentation-langchain/opentelemetry/instrumentation/langchain/patch.py

Test plan

• create_supervisor() with ToolNode no longer crashes
• Existing tests pass (list-based tools still work)

Summary by CodeRabbit

• Bug Fixes
  • Improved tool extraction logic in agent instrumentation to properly handle different types of tool wrapper implementations, ensuring consistent behavior across various agent configurations.

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: b9c226e8-a32c-4aa0-b9b6-0bfd6a4f4f9a

📥 Commits

Reviewing files that changed from the base of the PR and between 786d49f and 2a4413f.

📒 Files selected for processing (1)

• packages/opentelemetry-instrumentation-langchain/opentelemetry/instrumentation/langchain/patch.py

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📝 Walkthrough

Walkthrough

The patch updates the agent wrapper's tool extraction logic to handle ToolNode objects, which lack direct iterability. The code now checks for a tools_by_name attribute and iterates over its values when present, otherwise falling back to the original iteration behavior.

Changes

Cohort / File(s)	Summary
Tool Iteration Fix packages/opentelemetry-instrumentation-langchain/opentelemetry/instrumentation/langchain/patch.py	Added conditional logic to detect and iterate over tools.tools_by_name.values() for ToolNode-like objects that expose tools via this attribute, preventing TypeError on non-iterable tool wrappers.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related issues

• 🐛 Bug Report: TypeError: 'ToolNode' object is not iterable in patch.py when using langgraph-supervisor with create_react_agent #3841: This PR directly addresses the same issue of handling non-iterable ToolNode objects by implementing the conditional iteration pattern to access tools through the tools_by_name attribute.

Poem

🐰 A ToolNode came hopping around,
Not iterable, causing a sound,
But a clever refactor set it all right,
Now tools_by_name shines so bright! ✨
thump-thump goes the rabbit's delight! 🐇

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main fix: handling ToolNode in the tool extraction logic of create_agent_wrapper.
Linked Issues check	✅ Passed	The code changes fully implement the fix requirements from issue #3921: checking for tools_by_name attribute and iterating over its values for ToolNode, while preserving existing behavior for other iterables.
Out of Scope Changes check	✅ Passed	All changes are directly related to fixing the ToolNode handling issue described in issue #3921 with no unrelated modifications.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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