[FEATURE]: Add query parameter support for custom OpenAI-compatible providers #7198

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Describe the enhancement you want to request

Problem:
When configuring custom OpenAI-compatible providers, there's currently no way to add query parameters to API requests. Some OpenAI-compatible APIs require query parameters (e.g., ?api-version=2024-01-01) rather than or in addition to headers for configuration.
Currently, the @ai-sdk/openai-compatible package only supports:

• baseURL
• apiKey
• headers
• fetch (custom function)

Use Case:
Some providers like Azure OpenAI Service variants or custom enterprise APIs require query parameters for:

• API versioning (api-version)
• Tenant/workspace identifiers
• Feature flags or capabilities
• Authentication tokens in query string format

Current Workaround:
The only workaround is implementing a custom fetch function that intercepts requests and manually appends query parameters, which is not straightforward or well-documented.

Proposed Solution:
Add a queryParams option to provider configuration:

{
  provider: {
    custom-provider: {
      npm: @ai-sdk/openai-compatible,
      api: https://api.example.com/v1,
      options: {
        apiKey: your-key,
        queryParams: {
          api-version: 2024-01-01,
          tenant: my-org
        }
      }
    }
  }
}

These parameters would be automatically appended to all requests made to the provider.

Benefits:

• Cleaner configuration for APIs requiring query parameters
• No need for custom fetch implementations
• Consistent with how headers are already handled
• Enables support for more OpenAI-compatible API variants

Implementation Location:
The change would likely need to be made in:

• packages/opencode/src/provider/provider.ts (lines 892-975, where SDK options are processed)
• packages/opencode/src/provider/sdk/openai-compatible/src/openai-compatible-provider.ts (where URLs are constructed)