providers: GitHub Copilot Free lists no models (model_picker_enabled=false drops all; configured models ignored) #56434

Summary

With a connected GitHub Copilot Free account, OpenCode v2.0.27 lists zero Copilot models, so every model reference fails with Model unavailable: github-copilot/<model>. The same models work when called directly against the Copilot API with the stored credential. Explicitly declaring the models under providers.github-copilot.models does not help.

Environment

• opencode version: v2.0.27
• OS: Windows 10.0.19045.6811 (win32 x64)
• Terminal: Unavailable: terminal environment variables are not set
• Shell: PowerShell (powershell.exe) / cmd.exe
• Install/channel: latest
• Active plugins: opencode-models-discovery 1.10.0

Reproduction

1. Connect GitHub Copilot via device OAuth on a Copilot Free account. opencode auth list then shows GitHub Copilot GitHub Copilot stored.

2. Confirm the entitlement from the shell (token from opencode auth export):
   GET https://api.github.com/copilot_internal/user returns 200 with
   {"access_type_sku":"free_limited_copilot","chat_enabled":true,"cli_enabled":true,"copilot_plan":"individual","endpoints":{"api":"https://api.individual.githubcopilot.com",...}}.

3. GET https://api.githubcopilot.com/models with the stored OAuth access token returns 200 with 52 models. Every model has "model_picker_enabled": false; several have "policy":{"state":"enabled"} (for example gpt-4.1, gpt-4o, gpt-4o-mini).

4. In OpenCode, open /models (or GET /api/model): there are no github-copilot models at all.

5. Add the models to the global config anyway:

   {
     "providers": {
       "github-copilot": {
         "models": {
           "gpt-4.1": { "name": "GPT-4.1 (Copilot Free)" },
           "gpt-4o": { "name": "GPT-4o (Copilot Free)" }
         }
       }
     }
   }

   Reload and restart (the latter also with opencode service restart). GET /api/model still shows no github-copilot models.

6. opencode run --model github-copilot/gpt-4.1 "..." fails with:

   Error: Model unavailable: github-copilot/gpt-4.1
   

Expected Behavior

Models the account can actually use (gpt-4.1, gpt-4o, gpt-4o-mini) appear in /models, and/or models explicitly declared under providers.github-copilot.models are kept and selectable. The providers guide states that models "add or override" a provider's models.

Actual Behavior

• GET /api/model returns zero github-copilot models, while other providers return their models.
• Config-declared Copilot models are silently discarded. Model unavailable: github-copilot/gpt-4.1.
• The same config mechanism works for another catalog provider: adding a model under providers.groq.models makes it appear in GET /api/model, so config parsing/merging is not the problem.

The Copilot provider is reachable:

GET  /api/provider/github-copilot
=> activation: "enabled"
   package:    "@opencode/ai/providers/openai-compatible"
   settings:   { "baseURL": "https://api.githubcopilot.com" }
   (no models)

Chat completions succeed directly with the stored credential:

POST https://api.githubcopilot.com/chat/completions
Authorization: Bearer <stored token>
{"model":"gpt-4.1","messages":[{"role":"user","content":"ok?"}]}

=> 200 {"choices":[{"message":{"content":"ok",...}}]}

gpt-4o and gpt-4o-mini also return 200. gpt-4.1-2025-04-14 returns 200. Other policy.state=enabled models (gpt-5.6-luna, gpt-6-luna, mai-code-1.1-flash, claude-haiku-4.5) return 400 model_not_supported on the account.

Additional Context

• GET https://api.github.com/copilot_internal/v2/token returns 403 with an empty body for this account, even with Editor-Version, Editor-Plugin-Version and Copilot-Integration-Id headers, and for both Authorization: Bearer and Authorization: token. If the Copilot model sync depends on that exchange it would fail here. Both https://api.githubcopilot.com/models and https://api.individual.githubcopilot.com/models return 200 with the stored token directly.
• The docs say a failed sync is logged as failed to sync GitHub Copilot models. ~/.local/share/opencode/log/opencode.log contains no such line and no copilot lines other than cli starting entries, so the sync appears to either never run or fail silently.
• opencode reload and opencode service restart (with the credential present at boot) do not change the result.
• The workspace location used for /api/model was the project directory; the Copilot credential is global.
• Workaround tried: none worked. The account's entitlement and the Copilot API itself are fine.

Possible root cause: OpenCode filters Copilot models by model_picker_enabled, which GitHub sets to false for Copilot Free accounts, and the Copilot discovery path then replaces the provider's model map instead of merging configured models into it.