Foundry /openai/v1 endpoint only supports preview api-version (2025-11-15-preview)

[achandmsft]

Summary

The OpenAI /v1 API at api.openai.com doesn't use an api-version query parameter — the Responses API is GA on OpenAI's platform. However, the Foundry /openai/v1 endpoint requires api-version as a mandatory query parameter, and only accepts 2025-11-15-preview. There is no GA api-version for this route yet.

Current Behavior

• Without api-version: 400 Missing required query parameter: api-version
• With any non-preview version (e.g. 2024-10-21, 2025-03-01, 2025-06-01): 400 API version not supported
• Only 2025-11-15-preview works

Distinction

Component	Status
OpenAI Responses API	GA (stable, no versioning needed on openai.com)
OpenAI SDKs (Python, TS, C#, Java, Go)	Stable releases
Foundry /openai/v1 endpoint api-version	Only 2025-11-15-preview supported — no GA version exists yet

Impact

All examples in this repo must pass api-version=2025-11-15-preview as a query parameter. This adds language-specific complexity (e.g. C# requires a custom PipelinePolicy). Once a GA api-version ships, we should update all examples and documentation.

Action Items

• Monitor for a GA api-version on the Foundry /openai/v1 endpoint
• When available, update all 5 language examples to use the GA version
• Update README and copilot-instructions.md accordingly

[achandmsft]

Resolved. All examples now use the /openai/v1 base URL path, which is GA and does not require an api-version query parameter at all. The previous workaround of passing api-version=2025-11-15-preview is no longer needed. See commit cd64acc.