Endo

Endo is an open-source desktop app from Longsurf that works as a Higher Order Harness: it takes existing coding agents as building blocks and composes them within a single chat interface. It currently ships for macOS on Apple Silicon and can also be run from source. The README notes Endo is at 0.1.x, so breaking changes are expected.

What It Is

A conventional harness runs one agent by sending the prompt, running tools and keeping history. Endo instead treats agents as inputs and returns something that behaves like an agent: every composition answers in a thread you can talk to, dig into and schedule like any other chat. It drives Codex, Claude Code, Antigravity, Grok and OpenCode through their own CLIs, so you can use accounts you already have.

Workflows and Scheduling

A workflow is a TypeScript file in your workspace. It uses agent() to call a model from any provider, parallel() to fan calls out, and phase() to group them. A session ID lets a workflow continue an earlier agent's conversation. Running a workflow from chat shows a Workflow card with each call as it happens. Bundled workflows include /best-of-n, /multi-turn-debate, /thesis-killer and /hypothesis-race. Schedules can run any prompt later, on a cron or once.

Threads, Dig In and Memory

You can switch agents mid-thread, and each agent picks up the full history. Selecting part of an answer and choosing Dig In opens a focused side conversation, keeping the main thread clean. Sessions, runs and Dig Ins persist on your machine, so threads and branches survive a restart.

Setup and Extending

Install from the macOS disk image, or build from source with Node.js 24, Bun 1.4.2 and Just. Sign in to at least one provider, such as an existing codex, claude, Antigravity or grok login, or configure OpenCode's native providers. Developers can add Resources (typed API, agent tools and live updates from a Drizzle table and Effect Schema), agent tools, instruction segments and app pages.