[FEATURE]: Add Surplus Intelligence as a built-in provider

[i-seesharp]

• I have verified this feature I’m about to request hasn’t been suggested before.

Enhancement

Add Surplus Intelligence as a built-in OpenCode provider so users can discover and connect it through /connect without writing a custom provider configuration.

Surplus Intelligence is an OpenAI-compatible inference marketplace. Its default API base URL is:

https://api.surplusintelligence.ai/v1

Authentication uses a Surplus API key as a Bearer token. The provider should use the OpenAI-compatible AI SDK integration and expose Surplus-supported models in OpenCode’s model picker.

Benefits

• Makes Surplus available through OpenCode’s standard provider onboarding flow.
• Gives OpenCode users access to marketplace-routed inference behind one API key and endpoint.
• Removes the need to manually configure baseURL, provider package, credentials, and models.

Suggested acceptance criteria

• “Surplus Intelligence” appears in /connect and accepts an API key.
• Credentials are stored and resolved through OpenCode’s normal provider auth flow.
• The provider defaults to https://api.surplusintelligence.ai/v1 and uses Bearer authentication.
• Supported models appear under a stable provider ID in /models (including any required Models.dev catalog entry).
• Chat completions work in streaming and non-streaming modes, including tool calls.
• Provider setup is documented in the providers guide.
• Provider/auth/model-selection tests cover the built-in integration.

Surplus: https://surplusintelligence.ai

[i-seesharp]

Opened in the wrong repository. Apologies for the noise.