fix(vertex): convert Claude format to Gemini when RequestMode is Gemini

[JimmaaBinyamin]

Problem

When using Vertex AI with model redirection from Claude model names to Gemini models, /v1/messages requests failed with 400 error because ConvertClaudeRequest always returned Claude format regardless of RequestMode.

Solution

Added check for RequestModeGemini in ConvertClaudeRequest to delegate to Gemini adaptor's ConvertClaudeRequest method. This follows the same pattern already used in ConvertOpenAIRequest.

Changes

• relay/channel/vertex/adaptor.go: +7 lines

Testing

• go vet: Pass
• Local testing with Docker: Vertex AI + Claude format to Gemini redirection works correctly

Summary by CodeRabbit

• Refactor
  • Optimized request routing for improved handling between Claude and Gemini models.

[coderabbitai]

Walkthrough

Added an early conditional in ConvertClaudeRequest within the Vertex adaptor to route Claude requests destined for Gemini to the Gemini adaptor's handler. This delegates the Claude-to-Gemini conversion responsibility rather than handling it in-house, while preserving the original Vertex AI Claude path for non-Gemini targets.

Changes

Cohort / File(s)	Summary
Vertex Adaptor Request Routing relay/channel/vertex/adaptor.go	Added conditional branch to route Claude requests with Gemini target mode to gemini.Adaptor.ConvertClauseRequest, delegating conversion logic instead of handling internally.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• feat: deepseek claude endpoint #1832: Modifies ConvertClauseRequest to delegate Claude handling to a different adaptor by changing target adaptor routing.
• fix: volcengine claude DoResponse #2296: Delegates Claude requests to a different adaptor based on context (target mode or channel base URL) in ConvertClauseRequest.
• feat: Claude to gemini （适配claude格式调用gemini渠道模型） #1443: Implements the gemini.Adaptor.ConvertClauseRequest method that this PR routes Claude-to-Gemini conversions to.

Suggested reviewers

• seefs001

Poem

🐰 A Claude hops to Gemini's door,
No need to translate anymore,
Vertex says "go to your kin,"
The delegation wins,
Cleaner code and so much more! ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically describes the main change: adding a conversion from Claude format to Gemini when RequestMode is Gemini in the Vertex adaptor.

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✨ Finishing touches

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• Post copyable unit tests in a comment

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