GitHub Copilot models not appearing in /models after successful OAuth authentication

Description

Description:

OS: Windows 11 (PowerShell)
OpenCode version: v1.18.5 (latest)
Steps to reproduce:

Run /connect in the TUI
Select "GitHub Copilot" and complete the device flow at github.com/login/device
Authentication succeeds — auth.json stores the OAuth token correctly
Run /models — only big-pickle appears, no copilot models listed
Tried re-authenticating, clearing auth.json, clearing models.json cache — same result
What I expected: Copilot models (e.g., copilot/claude-sonnet-4.6, copilot/gpt-5.3-codex) should appear in /models after authentication.

What happened: No copilot models appear in the model picker. Also tried setting "model": "copilot/claude-sonnet-4.6" directly in opencode.jsonc but it doesn't work (provider doesn't seem to initialize).

Evidence:

~/.local/share/opencode/auth.json contains valid OAuth token for github-copilot
~/.cache/opencode/models.json lists 27 copilot models under github-copilot key
The provider simply doesn't surface in the TUI
Additional context: GitHub Copilot subscription is active (Pro/Pro+). Authentication flow completes without errors. The issue appears to be that the copilot provider doesn't initialize or register in the TUI despite having valid credentials and model data.

Plugins

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OpenCode version

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Steps to reproduce

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Screenshot and/or share link

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Operating System

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Terminal

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