OpenCode Zen & Go

OpenCode Zen (pay-per-use) and OpenCode Go (subscription) are model gateways run by the OpenCode team. Both are supported through the ModelConfig::opencode_zen() and ModelConfig::opencode_go() presets.

The gateways serve different model families over different protocols. The presets select the protocol automatically from the model id:

Gemini models on Zen are not supported — Zen serves them over a Google-native endpoint shape yoagent does not target. A gemini-* id falls through to Chat Completions (with a warning logged) and will fail at request time.

Jev models (jev-*) are not supported either — Zen serves them on its /systemone evaluation endpoint. They fall through the same way, with a warning.

claude-* ids get the same compat flags as the matching ModelConfig::claude_* preset, inferred from the version in the id (AnthropicCompat::for_claude_id): budget-based thinking before Claude 4.6 (e.g. Haiku 4.5), adaptive thinking from 4.6, and native structured outputs from 4.5 — so prompt_structured works on models that reject forced tool choice, such as Opus 5.5 and Fable 5.1.

The routing table mirrors the Zen/Go endpoint docs as of September 2026. OpenCode can change gateway-side routing at any time — if a model errors, verify its protocol against {base}/models.

Usage

Agent::from_config selects the built-in provider from the preset's protocol (config.api) and resolves the key from OPENCODE_API_KEY, so the same call works whichever model family you pick:

#![allow(unused)]
fn main() {
use yoagent::provider::ModelConfig;
use yoagent::Agent;

// Chat-completions model (GLM, Kimi, DeepSeek, ...)
let agent = Agent::from_config(ModelConfig::opencode_zen("glm-5.2"));

// Claude/Qwen model — Anthropic Messages protocol
let agent = Agent::from_config(ModelConfig::opencode_zen("claude-sonnet-5"));
}

For OpenCode Go, use ModelConfig::opencode_go("kimi-k2.7-code") — the base URL and protocol map differ, the usage pattern is identical.

Authentication

Both gateways use Authorization: Bearer {api_key}. For the Anthropic-protocol models the presets set AnthropicCompat::bearer_auth, so the Anthropic provider sends Bearer auth instead of its native x-api-key header. To do the same for another Messages-protocol gateway:

#![allow(unused)]
fn main() {
use yoagent::provider::{AnthropicCompat, ModelConfig};

let mut config = ModelConfig::anthropic("claude-sonnet-5", "Claude Sonnet 5");
config.base_url = "https://gateway.example.com/v1".into();
// Keep the options inferred from the id; switch only the auth header.
config.anthropic = Some(AnthropicCompat::for_claude_id("claude-sonnet-5").with_bearer_auth(true));
}

Get an API key by signing in at opencode.ai (Zen) or subscribing to Go.

Defaults

The presets use conservative defaults (128K context window, 16K max output). Override the fields for models with larger limits:

#![allow(unused)]
fn main() {
let mut config = ModelConfig::opencode_zen("kimi-k2.7-code");
config.context_window = 256_000;
}

Endpoints

• Zen: https://opencode.ai/zen/v1/{chat/completions | messages | responses}
• Go: https://opencode.ai/zen/go/v1/{chat/completions | messages | responses}

Model list and metadata: https://opencode.ai/zen/v1/models and https://opencode.ai/zen/go/v1/models.