Support opencode v2?

[eoleedi]

Feature Description
As stated in the title

[marcelokarval]

I can reproduce the V2 incompatibility with oc-codex-multi-auth@6.23.0 and the published @opencode/cli@2.0.16.

When the V2 loader reaches the plugin's built dist entry, registration fails with:

Plugin must export a default definition with an id and an effect or setup function.

The package currently default-exports the V1 OpenAIOAuthPlugin function. V2 resolves a server entry (falling back to the root entry) and expects an identified setup/effect definition. Merely changing the export shape is not sufficient: auth registration, request interception, retry/rotation, tools, and lifecycle cleanup need their actual V2 contracts.

Native V2 baseline

I also ran six controlled scenarios against the real 2.0.16 executable with the built-in OpenAI provider, two synthetic OAuth credential records and a local Responses/SSE fixture. No external plugins, real accounts, or subscription quota were used. Transport was explicitly HTTP, not WebSocket.

• Credential A and B each succeeded independently.
• 429 insufficient_quota on A failed without trying B.
• Explicitly activating B and resending recovered the same failed session.
• Synthetic 429 usage_limit_reached and 429 rate_limit_exceeded each made 11 requests (initial + 10 retries), all using A, then failed. B was never selected.

These are controlled HTTP observations, not a real ChatGPT login/refresh or default-WebSocket acceptance test. They distinguish native multiple-credential storage/selection from automatic rotation; they should not be generalized to every possible provider response or future V2 release.

Proposed contribution scope

I am investigating an additive V2 server adapter, keeping the V1 entry intact and reusing the existing account/storage/request logic rather than replacing it with a second account manager. Proposed acceptance gates:

1. V2 loader registration and unload cleanup.
2. Existing V1 build/typecheck/tests remain valid.
3. Isolated positive and negative tests for credential selection, bounded retries, account isolation and cancellation, respecting existing cooldowns/provider limits.
4. Explicit HTTP versus WebSocket support boundaries; no silent claim of full parity.
5. Documentation and package entry points that do not rewrite an existing user's configuration unexpectedly.

I will keep implementation linked to this issue rather than opening a duplicate. If there is already an unpublished V2 branch or a preferred adapter direction, please point me to it before overlapping work grows. This is an investigation/contribution start, not a claim that V2 support is implemented or ready to release.

[lubshad]

OpenCode V2 support was added in merged PR #269, which directly addresses this request