feat(llmobs): langgraph submits agent manifest

[sabrenner]

wip

langgraph submits agentic manifest, including (at a best effort):

• name (always)
• tools (always)
• instructions (if done through create_react_agent)
• model name, provider, & settings (if done through create_react_agent)
• handoffs (always)

additionally, patches create_react_agent, which has to deal with some circular importing patching errors.

MLOB-3102

Checklist

• PR author has checked that all the criteria below are met
• The PR description includes an overview of the change
• The PR description articulates the motivation for the change
• The change includes tests OR the PR description describes a testing strategy
• The PR description notes risks associated with the change, if any
• Newly-added code is easy to change
• The change follows the library release note guidelines
• The change includes or references documentation updates if necessary
• Backport labels are set (if applicable)

Reviewer Checklist

• Reviewer has checked that all the criteria below are met
• Title is accurate
• All changes are related to the pull request's stated goal
• Avoids breaking API changes
• Testing strategy adequately addresses listed risks
• Newly-added code is easy to change
• Release note makes sense to a user of the library
• If necessary, author has acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment
• Backport labels are set in a manner that is consistent with the release branch maintenance policy

[github-actions]

CODEOWNERS have been resolved as:

ddtrace/_monkey.py                                                      @DataDog/apm-core-python
ddtrace/contrib/internal/langgraph/patch.py                             @DataDog/ml-observability
ddtrace/llmobs/_integrations/langgraph.py                               @DataDog/ml-observability

[github-actions]

Bootstrap import analysis

Comparison of import times between this PR and base.

Summary

The average import time from this PR is: 287 ± 6 ms.

The average import time from base is: 286 ± 6 ms.

The import time difference between this PR and base is: 0.4 ± 0.3 ms.

The difference is not statistically significant (z = 1.36).

Import time breakdown

The following import paths have shrunk:

ddtrace.auto 1.814 ms (0.63%)

ddtrace.bootstrap.sitecustomize 1.141 ms (0.40%)

ddtrace.bootstrap.preload 1.141 ms (0.40%)

ddtrace.internal.remoteconfig.client 0.606 ms (0.21%)

ddtrace 0.673 ms (0.23%)

ddtrace.internal._unpatched 0.029 ms (0.01%)

json 0.029 ms (0.01%)

json.decoder 0.029 ms (0.01%)

re 0.029 ms (0.01%)

enum 0.029 ms (0.01%)

types 0.029 ms (0.01%)

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-07-07 19:49:30

Comparing candidate commit 6f9fd92 in PR branch sabrenner/langgraph-agentic-model with baseline commit d4aa8cd in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 507 metrics, 3 unstable metrics.