OpenCode agent provider

Install OpenCode as an optional NanoClaw runtime. The payload is included in this skill; it needs no separate provider branch. It uses the upstream runtime, instructions, host, and setup metadata contracts. The host contract remains at version 1; the container owns its non-secret ChatGPT placeholder file.

OpenCode is offered by the standard setup provider picker. Existing installs can add or authenticate it with pnpm exec tsx setup/index.ts --step provider-auth opencode. To replace an installed payload and update its pins, append --refresh; back up local payload edits first. Ordinary re-authentication leaves installed files and the container image alone. Backend defaults are installation-wide; model and reasoning effort can be overridden per group through the existing container configuration. Per-group backend/auth selection is separate work. Channel attachments reach the agent as a prompt line naming the staged file; the agent opens it with OpenCode's read tool, which hands images and PDFs to models that accept them (a custom model declares that with OPENCODE_MODEL_INPUT_MODALITIES).

Authentication checks the installed files, registration lines, and exact pins against this skill's declarations without launching a subprocess or container. Install and refresh run the existing provider contract verification; the build step owns image freshness. Model selection does not repeat installation checks. A working backend and account are checked separately by sending a real request.

Install