Agents SDK adds OpenCode 2.0 support via experimental OpenCodeHarness

The Agents SDK now supports OpenCode 2.0 ↗︎ through the experimental OpenCodeHarness. Run OpenCode inside a plain Durable Object, with sessions stored in SQLite and Lifecycle jobs that wake interrupted work after eviction.

The agents/models/opencode provider connects OpenCode to Workers AI through the AI binding. OpenCode plugins extend the harness with custom tools, remote MCP servers, and skills. Refer to OpenCode's Cloudflare SDK documentation ↗︎ for the embedded host API.

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Install Agents SDK 0.28.0 or later with the OpenCode packages:

npmyarnpnpmbun

npm i agents@latest @opencode/sdk@2 @opencode/plugin@2

yarn add agents@latest @opencode/sdk@2 @opencode/plugin@2

pnpm add agents@latest @opencode/sdk@2 @opencode/plugin@2

bun add agents@latest @opencode/sdk@2 @opencode/plugin@2

Create a harness and install a Lifecycle on your Durable Object:

import { DurableObject } from "cloudflare:workers";
import { Lifecycle } from "agents/lifecycle";
import { OpenCodeWorkerd } from "@opencode/sdk/workerd";
import { OpenCodeHarness } from "agents/harness/opencode";
import { createAI } from "agents/models/opencode";
import workerTools from "./worker-tools";

export class Assistant extends DurableObject {
	ai = createAI({ binding: this.env.AI });
	harness = new OpenCodeHarness({
		opencode: ({ storage }) =>
			OpenCodeWorkerd.create({
				storage,
				models: { fetch: false },
				plugins: [this.ai.plugin, workerTools],
			}),
		defaults: {
			model: this.ai("@cf/moonshotai/kimi-k2.7-code", {
				reasoningEffort: "low",
			}),
			agent: "build",
		},
	});

	lifecycle = Lifecycle.install(this).use(this.harness);

	async ask(prompt) {
		const { status, text, reason } = await this.harness.prompt(prompt);
		return { status, text, reason };
	}
}

import { DurableObject } from "cloudflare:workers";
import { Lifecycle } from "agents/lifecycle";
import { OpenCodeWorkerd } from "@opencode/sdk/workerd";
import { OpenCodeHarness } from "agents/harness/opencode";
import { createAI } from "agents/models/opencode";
import workerTools from "./worker-tools";

export class Assistant extends DurableObject<Env> {
	ai = createAI({ binding: this.env.AI });
	harness = new OpenCodeHarness({
		opencode: ({ storage }) =>
			OpenCodeWorkerd.create({
				storage,
				models: { fetch: false },
				plugins: [this.ai.plugin, workerTools],
			}),
		defaults: {
			model: this.ai("@cf/moonshotai/kimi-k2.7-code", {
				reasoningEffort: "low",
			}),
			agent: "build",
		},
	});

	lifecycle = Lifecycle.install(this).use(this.harness);

	async ask(prompt: string) {
		const { status, text, reason } = await this.harness.prompt(prompt);
		return { status, text, reason };
	}
}

The OpenCode harness guide includes the workerTools plugin, Wrangler configuration, and session APIs. The working example ↗︎ adds a browser UI, WebSocket streaming, and persistent note tools.