The YACO web server and the browser IDE it serves — a single-user, file-backed workspace for running coding agents on your own machine. One Node process serves the built React UI, the HTTP API, the WebSocket terminals and the SSE file/git/session watchers on a single port. There is no database: state is files under ~/.yaco and the repos you point it at.

This is layer 3 of YACO. YACO is an orchestration layer, not an agent — it never talks to a model. It starts, tracks, and attaches to the agent CLIs you already have.

It requires `yaco-cli`

The app does not own agent sessions. Session and task mutations shell out to the installed yaco binary (yaco agent …, yaco task …), and yaco-cli is what carries the workflow skills. Install both, then run the configure step:

npm install -g yaco-cli yaco-app
yaco install

yaco install merges the provider hooks into ~/.claude and ~/.codex, writes the agent wrapper script, links the skills, and finishes with yaco doctor. Re-run it after every upgrade.

Prerequisites

Linux or macOS, with:

Node.js ≥ 24.15 and npm.
tmux — every terminal in the app is a tmux session.
git.
Claude Code (claude) or Codex (codex) on your PATH — one is enough. YACO ships no agent; no session can run without one.
Linux only: make, python3, and a C/C++ compiler (sudo apt install make python3 build-essential) — this package depends on node-pty, which compiles from source on Linux.
Optional: ripgrep (rg) — cross-file text search returns 503 without it.

Run it

yaco-app

Open http://localhost:3001 and add your repo as a project. The server listens on all interfaces, so the same URL works from another machine on your LAN or tailnet — see YACO_ALLOWED_HOSTNAMES below for names that are not loopback, .local, or a private IPv4 address.

What you get

A deliberately simple IDE — editor, file explorer, cross-file search, git and diff views, terminals — plus the parts a plain IDE doesn't have:

Sessions that outlive the browser. Every terminal is a tmux session. Close the tab, restart the server, reattach later — from the app or a plain terminal.
The agent tree, and it tells you when it's your turn. Parent and child sessions rendered as the tree they are; a session that finished or is waiting on your reply reaches the notification panel, the session badge, and your browser's notifications.
The task graph under plan/, rendered live. Worksets, depends edges, per-task state, and a Gantt view — refreshed over SSE as the files change.
Git worktree isolation. Switch the whole workspace between main and any task/<slug> checkout.
The whole workspace on your phone, over your own network: touch layout, a terminal key bar, voice input.
Voice input built for prompting. Record, transcribe, auto-format the rambling into clean prose, then insert into the editor or paste straight into an agent's terminal.

Configuration

Everything above runs with zero configuration except the AI text helpers.

Variable	What it gates
`GROQ_API_KEY`	Groq voice transcription, transcript auto-formatting, and markdown inline suggestions. Absent, each of those reports itself unavailable.
`WORKFLOW_PORT`	HTTP + WebSocket port. Default `3001`.
`YACO_HOME`	Runtime state root — projects, sessions, UI state. Default `~/.yaco`.
`YACO_ALLOWED_HOSTNAMES`	Extra hostnames the CORS and WebSocket origin guard trusts, comma-separated. A leading dot covers subdomains (`.example.ts.net`). Loopback, `.local`, and private IPv4 are already trusted.
`WORKFLOW_CORS_ORIGINS`	Comma-separated exact origins. When set it replaces the allowlist entirely.
`CODEX_HOME`	Where to find the Codex CLI's OAuth file for Codex transcription. Default `~/.codex`.

Voice transcription needs either a signed-in Codex CLI or GROQ_API_KEY; formatting and inline suggestions need GROQ_API_KEY. Model selection has its own overrides — GROQ_TRANSCRIPTION_MODEL, VOICE_FORMATTER_MODELS, AUTOCOMPLETE_MODELS, VOICE_TTS_VOICE — all optional.

Set these in the server's environment, or in a .env file in the directory you start yaco-app from.

Inline suggestions are markdown-only and off by default: nothing leaves the machine until you turn them on.