V2: GitHub Copilot login and per-request headers not supported

[kitlangton]

Summary

On the v2 branch, GitHub Copilot is catalog/SDK-only: there is no Copilot login method, and none of the required per-request headers / token handling that V1 injects. Copilot requests will not work correctly (and cannot authenticate via the Copilot OAuth flow).

Part of the systemic V2 provider-login gap (see #34765).

Evidence

• packages/core/src/plugin/provider/github-copilot.ts only does a catalog tweak (hide gpt-5-chat-latest) and picks responses vs chat via shouldUseResponses. No ctx.integration.transform, no login method, no request-header injection, no Copilot token exchange.
• Only openai and opencode register OAuth methods in packages/core/src/plugin/provider/.

How V1 does it (reference)

packages/opencode/src/plugin/github-copilot/copilot.ts:

• Registers a GitHub OAuth device-code login; exchanges the GitHub token for a Copilot token.
• Endpoint selection: https://api.githubcopilot.com (or https://copilot-api.<enterprise-domain> for enterprise).
• loader custom fetch that, for OAuth credentials, on every request:
  • inspects the body to classify vision/agent requests,
  • sets Authorization: Bearer <copilot-token>, User-Agent: opencode/<version>, Openai-Intent: conversation-edits, x-initiator: agent|user, and Copilot-Vision-Request: true when images are present,
  • strips inbound x-api-key / authorization.
• A chat.headers hook also sets X-GitHub-Api-Version, X-Interaction-Type, and anthropic-beta for Claude-via-Copilot models.

These headers are required by the Copilot backend; without them requests are rejected or mis-attributed.

What V2 needs

1. Register the Copilot login method (GitHub OAuth device flow + Copilot token exchange/refresh) in github-copilot.ts.
2. Request-time header injection: Authorization (Copilot token), Editor-Version/User-Agent, X-GitHub-Api-Version, Openai-Intent, x-initiator, and conditional Copilot-Vision-Request; strip inbound x-api-key/authorization.
3. Correct base URL (api.githubcopilot.com / enterprise variant).

Some of this (vision/agent classification from the request body) is genuinely dynamic and needs the fetch/Auth.custom escape hatch, but the static headers and endpoint should go through the shared credential-aware request hook proposed in #34765 so both the AI SDK and native @opencode-ai/llm paths are covered.

Environment

• Branch: v2
• Status: verified against source; not runtime-reproduced.

[opencode-agent]

Tracker update from V2 TODO LIST audit (2026-07-02):

This is part of the broader V2 provider-login / credential-aware request-routing gap. Please coordinate with:

• V2: ChatGPT subscription (OpenAI OAuth) not routed to codex backend — HTTP 401 missing api.responses.write #34765 for the ChatGPT/OpenAI OAuth case and shared request-routing discussion
• feat(llm): add native provider packages #33689 / feat(core): load native provider packages #33925 / feat: flatten provider config and load native packages #34462 for the native provider package loading/config stack

The likely durable fix should live at the native provider package / provider-resolution seam so OAuth credential metadata and per-provider request headers/base URLs work across the native @opencode-ai/llm path, instead of re-porting one-off V1 fetch monkey-patches.

[opencode-agent]

Audit update (2026-07-08): #34843 only fixed ChatGPT/OpenAI OAuth routing (#34765); it did not add GitHub Copilot login or per-request auth/header handling. This issue remains open and is not resolved by that cross-reference.

[opencode-agent]

Addressed by #36336 and completed by #38184. V2 now provides GitHub and GitHub Enterprise device OAuth, credential-aware Copilot request authentication and required headers, remote model syncing, endpoint selection, and account-specific API endpoint discovery. That covers the login, per-request header/token handling, and base-URL requirements described here. Closing as resolved on the v2 branch.