github-copilot plugin does not see Enterprise BYOK models

Description

Github Copilot API is hiding models unless a specific set of headers are provided.

• https://api.githubcopilot.com/models does not list the model
• https://api.githubcopilot.com/chat/completions does not recognize the model as supported

The specific header missing is:

Copilot-Integration-Id: vscode-chat

This header should be provided to /models and /chat/completions.

This header was provided in the past, but that change got squashed as a result of this refactor:

• a433766a31fbf5c0597aec757de59a3d882c02fa

As the API mostly works, this limitations has gone unnoticed.

In my testing, the issue can be resolved by changing packages/opencode/src/plugin/github-copilot/copilot.ts, function CopilotAuthPlugin:

         return CopilotModels.get(
           base(auth.enterpriseUrl),
           {
             ...(provider.options?.headers as Record<string, string> | undefined),
             Authorization: `Bearer ${auth.refresh}`,
             "User-Agent": `opencode/${InstallationVersion}`,
             "X-GitHub-Api-Version": API_VERSION,
+            "Copilot-Integration-Id": "vscode-chat",
           },
           provider.models,
         )

I tested the fix on dev. There may be other fixes to github-copilot that are queued on dev, not yet released in 2.0.10, that are also necessary to resolved this problem.

Plugins

github-copilot

OpenCode version

2.0.10

Steps to reproduce

1. Enable Github Copilot Enterprise BYOK with one or more custom models.
2. Confirm the models shows up in VS Code.
3. Confirm the models are absent from OpenCode after /connect.

After the fix, the models should be listed and selectable without any customization to opencode.json.

Screenshot and/or share link

Not useful.

Operating System

EL 8

Terminal

Xfce4

Start in packages/opencode/src/plugin/github-copilot/copilot.ts at CopilotAuthPlugin and inspect how headers are passed to CopilotModels.get for /models and /chat/completions. Reproduce with an Enterprise BYOK custom model, then verify the model is listed and selectable after connecting without opencode.json customization.