Make Vertex AI evaluation optional to avoid litellm bloat

[Vamsi-klu]

Problem

apache-airflow-providers-google pulled google-cloud-aiplatform[evaluation] into the base provider install. That extra brings in evaluation-only dependencies such as litellm, scikit-learn, huggingface-hub, and tokenizers for users who may only need unrelated Google services.

The only code path that needs vertexai.preview.evaluation is Vertex AI model evaluation through GenerativeModelHook.get_eval_task(), GenerativeModelHook.run_evaluation(), and RunEvaluationOperator.

What Changed

• Changed the base dependency to google-cloud-aiplatform>=1.155.0.
• Added an evaluation provider extra that installs google-cloud-aiplatform[evaluation]>=1.155.0.
• Added an import guard that raises AirflowOptionalProviderFeatureException with an install instruction when evaluation APIs are used without the extra.
• Added a provider changelog note for the breaking dependency split.
• Updated generated provider dependency docs and uv.lock.
• Added a follow-up regression test for the missing-extra path and documented the evaluation extra in the Vertex AI operator docs.

Why The Follow-Up Commit Exists

The feedback was correct: the original PR proved the opt-in path but did not directly test the failure mode when the extra is missing, did not document the extra next to RunEvaluationOperator, and left the lockfile inconsistent with the dependency split.

Impact

• Base Google provider installs no longer pull the evaluation dependency stack.
• Users of RunEvaluationOperator or direct Vertex AI evaluation hook methods must install apache-airflow-providers-google[evaluation].
• Users who do not use evaluation APIs should see no runtime behavior change.

Fixes: #69323

Testing

• UV_CACHE_DIR=/tmp/uv-cache-69749 uv run --python 3.11 ruff format providers/google/tests/unit/google/cloud/hooks/vertex_ai/test_generative_model_optional_evaluation.py
• UV_CACHE_DIR=/tmp/uv-cache-69749 uv run --python 3.11 ruff check --fix providers/google/tests/unit/google/cloud/hooks/vertex_ai/test_generative_model_optional_evaluation.py
• AIRFLOW_HOME=/tmp/airflow-home-69749 UV_CACHE_DIR=/tmp/uv-cache-69749 uv run --python 3.11 --project providers/google pytest providers/google/tests/unit/google/cloud/hooks/vertex_ai/test_generative_model_optional_evaluation.py --with-db-init -xvs
• Result: 2 passed, 1 warning
• AIRFLOW_HOME=/tmp/airflow-home-69749 UV_CACHE_DIR=/tmp/uv-cache-69749 uv run --python 3.11 --project providers/google --extra evaluation pytest providers/google/tests/unit/google/cloud/hooks/vertex_ai/test_generative_model.py providers/google/tests/unit/google/cloud/operators/vertex_ai/test_generative_model.py -xvs
• Result: 2 passed, 1 warning
• Commit hooks passed for the follow-up commit.

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Was generative AI tooling used to co-author this PR?

• Yes — Codex (GPT-5)

Generated-by: Codex (GPT-5) following the guidelines

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Drafted-by: Codex (GPT-5); reviewed by @Vamsi-klu before posting

[Vamsi-klu]

Reviewers: @shahar1 (google provider CODEOWNER). Breaking change: evaluation extra now optional to avoid litellm bloat. Changelog entry added, provider docs regenerated via update-providers-dependencies.

Fixes #69323

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Drafted-by: Muse Spark 1.1; reviewed by @Vamsi-klu before posting

[github-actions]

uv.lock on main just moved via #67343 ("Update Weaviate examples for client 4.16 API"), commit 424c4a7 and this PR currently conflicts.

Quickest fix:

git fetch upstream main && git rebase upstream/main
rm uv.lock && uv lock
git add uv.lock && git rebase --continue
git push --force-with-lease

Automated nudge — ignore if you're not ready to rebase. This comment is updated in place on future uv.lock bumps.

[potiuk]

@Vamsi-klu This PR has been converted to draft because it does not yet meet our Pull Request quality criteria.

Issues found:

• ❌ Merge conflicts: This PR has merge conflicts with main and cannot be merged as-is. Rebase locally and resolve them: git fetch upstream main && git rebase upstream/main, resolve the conflicts, then force-push.

Note: Your branch is 147 commits behind main. Some check failures may be caused by changes in the base branch rather than by your PR. Please rebase your branch and push again to get up-to-date CI results.

What to do next:

• Fix each issue listed above.
• Make sure static checks pass locally (prek run --from-ref main --stage pre-commit).
• Mark the PR as "Ready for review" when you're done.

Converting a PR to draft is not a rejection — it is an invitation to bring the PR up to the project's standards so that maintainer review time is spent productively. There is no rush — take your time and work at your own pace. We appreciate your contribution and are happy to wait for updates. If you have questions, feel free to ask on the Airflow Slack.

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