feat(langchain): split provider integrations into optional extras

[marcusds]

Summary

nvidia-nat-langchain currently declares every langchain provider integration as a required dependency:

langchain-aws, langchain-community, langchain-exa, langchain-huggingface, langchain-litellm, langchain-milvus, langchain-nvidia-ai-endpoints, langchain-oci, langchain-openai, langchain-tavily, plus openevals and wikipedia.

A consumer that only configures _type: openai + _type: react_agent (the minimum to run a basic ReAct agent) still pulls all of them. That blows up wheel size, slows pip resolution, and -- most painfully -- transitive langchain-aws / boto3 / botocore constraints have been triggering ResolutionTooDeep failures downstream that require manual pinning to work around.

The good news: every provider module is already lazy-imported inside the matching register_llm_client / register_function body, so the install-time deps were only nominally required. This PR promotes that reality into the package metadata.

Dependency split

Core deps (always installed), matching what is actually imported at module load time:

• langchain, langchain-classic, langchain-core, langgraph
• nvidia-nat-{core,eval,opentelemetry}
• pyopenssl (existing transitive pin)

Optional extras (provider integrations):

Extra	Pulls in
[aws]	langchain-aws
[community]	langchain-community, wikipedia
[exa]	langchain-exa
[huggingface]	langchain-huggingface
[judge]	openevals (LLM-as-judge eval)
[litellm]	langchain-litellm
[milvus]	langchain-milvus
[nvidia]	langchain-nvidia-ai-endpoints
[oci]	langchain-oci
[openai]	langchain-openai
[tavily]	langchain-tavily
[all]	All of the above

Backwards compatibility

Both the top-level nvidia-nat[langchain] and nvidia-nat[most] extras now resolve to nvidia-nat-langchain[all] == {version}, so anyone installing the toolkit via the umbrella distribution continues to get the exact same resolved tree as today. Only the bare pip install nvidia-nat-langchain install surface shrinks; users who depend on a specific provider need to add the corresponding extra (e.g. pip install \"nvidia-nat-langchain[openai]\").

uv.lock has been regenerated against the new graph.

Why this is safe today

A grep across packages/nvidia_nat_langchain/src/ confirms only langchain_core, langchain_classic, and langgraph appear in top-level from ... import ... statements. Every provider module (langchain_aws, langchain_openai, langchain_oci, langchain_huggingface, langchain_litellm, langchain_milvus, langchain_exa, langchain_tavily, langchain_community, langchain_nvidia_ai_endpoints) is imported lazily inside its registration function. openevals is already wrapped in a try/except ImportError in eval/langsmith_judge.py. So the split changes which deps pip installs, not which code paths execute.

Test plan

• CI green on develop-targeted PR (existing tests should pass unchanged because [all] is installed in the test extra)
• uv sync --extra langchain --extra most resolves the same provider set as before
• pip install "nvidia-nat-langchain[openai]" succeeds without pulling langchain-aws / boto3
• pip install "nvidia-nat-langchain" is enough to import nat.plugins.langchain and use _type: react_agent

Summary by CodeRabbit

• New Features

  • Provider-specific optional extras (aws, openai, community, etc.) available for selective integration installation.
  • New "all" extra installs all provider integrations together for full functionality.

• Chores

  • Dependency layout restructured: core packages installed by default; provider integrations moved to optional extras for flexible setup.
  • Install groups and test tooling updated so aggregated extras (e.g., "most", "langchain" and test) now pull the "all" provider bundle.

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• packages/nvidia_nat_langchain/pyproject.toml
• pyproject.toml

✅ Files skipped from review due to trivial changes (1)

• pyproject.toml

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Walkthrough

This PR separates provider integrations from core packages by moving provider langchain-* dependencies into optional extras on nvidia-nat-langchain (including an all extra) and updates the root pyproject.toml to depend on nvidia-nat-langchain[all] where appropriate.

Changes

Dependency Structure Refactoring

Layer / File(s)	Summary
nvidia-nat-langchain dependency restructuring packages/nvidia_nat_langchain/pyproject.toml	Core [tool.setuptools_dynamic_dependencies].dependencies reduced to core nvidia-nat-* and LangChain/LangGraph libs; added provider-scoped optional-dependencies (aws, community, exa, huggingface, judge, litellm, milvus, nvidia, oci, openai, tavily) and an all extra; test extra updated to include nvidia-nat-langchain[all].
Root pyproject.toml extras consumption pyproject.toml	langchain optional extra and most developer group updated to depend on nvidia-nat-langchain[all] instead of the non-[all] package.

🎯 3 (Moderate) | ⏱️ ~20 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and accurately describes the main change: splitting provider integrations from required dependencies into optional extras.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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⚠️ Outside diff range comments (1)

pyproject.toml (1)

1-1: ⚠️ Potential issue | 🟡 Minor | ⚡ Quick win

Update copyright year range for consistency.

The copyright header shows only "2026", but the root pyproject.toml almost certainly existed in 2025 (the package file at packages/nvidia_nat_langchain/pyproject.toml shows "2025-2026"). Per the guideline to "confirm that copyright years are up-to date whenever a file is changed", the range should be updated to reflect the file's history.

📅 Proposed fix

-# SPDX-FileCopyrightText: Copyright (c) 2026, NVIDIA CORPORATION & AFFILIATES.
+# SPDX-FileCopyrightText: Copyright (c) 2025-2026, NVIDIA CORPORATION & AFFILIATES.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@pyproject.toml` at line 1, Update the SPDX copyright header line that
currently reads "Copyright (c) 2026, NVIDIA CORPORATION & AFFILIATES." to the
full range "2025-2026" so it matches the repository's root/package metadata;
locate the SPDX header line in this file (the first line) and replace the
single-year value with the range "2025-2026" to keep copyright years consistent.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Outside diff comments:
In `@pyproject.toml`:
- Line 1: Update the SPDX copyright header line that currently reads "Copyright
(c) 2026, NVIDIA CORPORATION & AFFILIATES." to the full range "2025-2026" so it
matches the repository's root/package metadata; locate the SPDX header line in
this file (the first line) and replace the single-year value with the range
"2025-2026" to keep copyright years consistent.

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• packages/nvidia_nat_langchain/pyproject.toml
• pyproject.toml