feat: normalize OpenAI base URL to support both formats

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Related GitHub Issue

Closes: #10337

Description

This PR attempts to address Issue #10337 by implementing the suggestion from @politsin to support both URL formats for custom OpenAI base URLs.

The Problem:
When using the "Use a custom base URL" checkbox, users were confused about whether to include /v1 in their base URL. Some OpenAI-compatible APIs expect the URL without /v1 (they append it themselves), while others expect the full URL including /v1.

The Solution:

1. URL Normalization Utility: Added normalizeOpenAiBaseUrl() function that handles both formats:

   • https://my-host.example -> https://my-host.example
   • https://my-host.example/v1 -> https://my-host.example
   • Strips trailing slashes and /v1 suffix to normalize the URL

2. Backend Integration: Updated openai-native.ts to use the normalization function in both:

   • OpenAI SDK client initialization
   • Manual SSE fallback request URL construction

3. UI Guidance: Added a hint text below the custom base URL field explaining that both formats are supported.

Test Procedure

1. Unit Tests: Run cd src && npx vitest run utils/__tests__/normalizeOpenAiBaseUrl.spec.ts

   • 25 tests covering various URL formats and edge cases

2. Manual Testing:

   • Enable "Use custom base URL" checkbox for OpenAI provider
   • Enter URL without /v1: https://api.openai.com
   • Enter URL with /v1: https://api.openai.com/v1
   • Both should work correctly without double /v1/v1 in the request path

Pre-Submission Checklist

• Issue Linked: This PR is linked to an approved GitHub Issue (see "Related GitHub Issue" above).
• Scope: My changes are focused on the linked issue (one major feature/fix per PR).
• Self-Review: I have performed a thorough self-review of my code.
• Testing: New and/or updated tests have been added to cover my changes (if applicable).
• Documentation Impact: I have considered if my changes require documentation updates (see "Documentation Updates" section below).
• Contribution Guidelines: I have read and agree to the Contributor Guidelines.

Documentation Updates

• No documentation updates are required.

Additional Notes

Feedback and guidance are welcome!

---

Important

Introduces normalizeOpenAiBaseUrl() to standardize OpenAI base URLs, updating backend and UI components, with comprehensive tests.

• Behavior:
  • Added normalizeOpenAiBaseUrl() function in normalizeOpenAiBaseUrl.ts to normalize OpenAI base URLs by removing /v1 suffix and trailing slashes.
  • Updated openai-native.ts to use normalizeOpenAiBaseUrl() for SDK client initialization and SSE fallback request URL.
  • Added UI hint in OpenAI.tsx to inform users that both URL formats are supported.
• Testing:
  • Added unit tests in normalizeOpenAiBaseUrl.spec.ts to cover various URL formats and edge cases.

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Rooviewer   See task on Roo Cloud

Review complete. No issues found.

The implementation correctly normalizes OpenAI base URLs to support both formats (with and without /v1 suffix). The utility function is well-tested with 25 comprehensive test cases covering various edge cases.

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