Python: fix(google-ai): skip api_key check when use_vertexai is True

[giulio-leone]

Summary

Fixes #13483

Motivation and Context

When use_vertexai=True, users authenticate via Application Default Credentials (ADC) and don't need an API key. However, the initialization check for api_key runs unconditionally, blocking Vertex AI users with:

ServiceInitializationError: The API key is required when use_vertexai is False.

Description

Guard the api_key validation with not google_ai_settings.use_vertexai in all three Google AI service classes:

• GoogleAIChatCompletion
• GoogleAITextCompletion
• GoogleAITextEmbedding

The error message already reads "when use_vertexai is False", so the condition now matches the intent.

Before / After

# Before — fails even with use_vertexai=True
GoogleAIChatCompletion(
    use_vertexai=True,
    cloud_project_id="my-project",
    cloud_region="us-central1"
)
# → ServiceInitializationError: The API key is required when use_vertexai is False.

# After — works correctly
GoogleAIChatCompletion(
    use_vertexai=True,
    cloud_project_id="my-project",
    cloud_region="us-central1"
)
# → Initializes successfully, uses ADC for authentication

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the SK Contribution Guidelines
• The code follows the SK coding standards

[giulio-leone]

@microsoft-github-policy-service agree

[giulio-leone]

Friendly ping — CI is green and this is ready for review. Happy to address any feedback. Thanks!

[Copilot]

Pull request overview

This PR fixes Google AI connector initialization for Vertex AI usage by skipping the api_key requirement when use_vertexai=True, aligning the validation logic with the intended ADC authentication path.

Changes:

• Guard api_key validation with not use_vertexai in GoogleAIChatCompletion.
• Guard api_key validation with not use_vertexai in GoogleAITextCompletion.
• Guard api_key validation with not use_vertexai in GoogleAITextEmbedding.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
python/semantic_kernel/connectors/ai/google/google_ai/services/google_ai_chat_completion.py	Skip API key validation when using Vertex AI during initialization.
python/semantic_kernel/connectors/ai/google/google_ai/services/google_ai_text_completion.py	Skip API key validation when using Vertex AI during initialization.
python/semantic_kernel/connectors/ai/google/google_ai/services/google_ai_text_embedding.py	Skip API key validation when using Vertex AI during initialization.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[giulio-leone]

Hi! Gentle ping — this PR is rebased, CI passes, and ready for review. Happy to address any feedback. Thanks!

[giulio-leone]

Friendly ping — CI is green, tests pass, ready for review whenever convenient. Happy to address any feedback. Thanks! 🙏

[giulio-leone]

Hi — all 4 threads resolved. cloud_region validation added to all 3 service classes. Fixes #13483. Ready for review!

[giulio-leone]

Rebased this branch onto current main (bb421f67a, PR #13686) and reran local validation twice with no code changes between passes.

Local validation (Pass 1 and Pass 2)

• UV_PYTHON=3.10 uv run --frozen ruff check semantic_kernel/connectors/ai/google/google_ai/services/google_ai_chat_completion.py semantic_kernel/connectors/ai/google/google_ai/services/google_ai_text_completion.py semantic_kernel/connectors/ai/google/google_ai/services/google_ai_text_embedding.py tests/unit/connectors/ai/google/google_ai/services/test_google_ai_chat_completion.py tests/unit/connectors/ai/google/google_ai/services/test_google_ai_text_completion.py tests/unit/connectors/ai/google/google_ai/services/test_google_ai_text_embedding.py
  • both passes: All checks passed!
• UV_PYTHON=3.10 uv run --frozen pytest tests/unit/connectors/ai/google/google_ai/services/test_google_ai_chat_completion.py tests/unit/connectors/ai/google/google_ai/services/test_google_ai_text_completion.py tests/unit/connectors/ai/google/google_ai/services/test_google_ai_text_embedding.py
  • both passes: 53 passed

Direct runtime proof (real source files, not mocks)

Using the real origin/main source tree vs this rebased branch with:

• GOOGLE_AI_GEMINI_MODEL_ID=test-gemini-model-id
• GOOGLE_AI_EMBEDDING_MODEL_ID=test-embedding-model-id
• GOOGLE_AI_CLOUD_PROJECT_ID=test-project-id
• GOOGLE_AI_CLOUD_REGION=test-region
• no GOOGLE_AI_API_KEY

Results were identical across both proof passes:

Case	Chat	Text	Embedding
origin/main + use_vertexai=True + no api_key	ServiceInitializationError: The API key is required when use_vertexai is False.	same	same
PR branch + use_vertexai=True + no api_key	initializes successfully	initializes successfully	initializes successfully
PR branch + use_vertexai=True + missing cloud_region	ServiceInitializationError: Region must be provided when use_vertexai is True.	same	same

So the rebased PR still fixes the original bug on all 3 Google AI service initializers while preserving the new cloud_region validation path.

[moonbox3]

Just need the CI/CD checks to pass and we'll get this merged. We will monitor.