OpenCode setup
Use Project Zero inside OpenCode, with no plugin, no fork and no pasted key.
OpenCode talks to Tessen as an OpenAI-compatible provider. The Tessen CLI writes that provider for you and hands OpenCode the credential your device sign-in produced.
curl -fsSL https://github.com/TessenLab/zero/releases/latest/download/install.sh | sh
tessen auth:login
tessen opencode
opencode --model tessen/project-zeroThe installer requires Node.js 20 or newer, on macOS, Linux or WSL. It downloads the CLI from Tessen's GitHub release, checks its SHA-256, and installs into ~/.tessen/cli without sudo. Re-run it to upgrade; remove ~/.tessen/cli and ~/.local/bin/tessen to uninstall.
What gets written
The provider goes into OpenCode's config (~/.config/opencode/opencode.json, or your existing opencode.jsonc). Other providers in that file are kept. The credential goes into OpenCode's own credential store (~/.local/share/opencode/auth.json, mode 0600) — never into the config file.
{
"$schema": "https://opencode.ai/config.json",
"provider": {
"tessen": {
"npm": "@ai-sdk/openai-compatible",
"name": "Tessen",
"options": { "baseURL": "https://api.tessen.ai/v1" },
"models": {
"project-zero": {
"name": "Project Zero",
"options": { "program": "project_zero" }
}
}
}
}
}Choosing Project Zero
In OpenCode, select tessen/project-zero — from the model picker, or with --model on the command line.
When a request is refused
| Status · code | Meaning |
|---|---|
| 401 | The credential is missing, revoked or expired. Run tessen auth:login, then tessen opencode. |
| 403 · zero_entitlement_required | This account does not have Project Zero access. tessen zero shows your access. |
| 503 · zero_capacity_unavailable | No zero-cost capacity can serve the request right now, or today's pool is used. Retry after the reset the response names. |
| 503 · zero_program_disabled | Project Zero is switched off by Tessen. It is not your account and not the pool; normal Tessen is unaffected. |