How Custard works.

Custard is a Mac app for macOS 13 or later, built for Apple silicon. It works with the coding agents you already have, so install at least one of them first: Claude Code, Codex, OpenCode or Antigravity.

1. Download Custard and drag it into Applications.
2. Open it. Custard finds the coding agents on your Mac and shows which are ready, which need a sign-in, and which aren't installed.
3. Pick a Project folder. You land in an Agent's Home, ready to go.

A handful of words, and they mean the same thing everywhere in the app.

Agent

A named coding agent with a role and a face. It stays around and remembers your decisions from one task to the next.

Home

An Agent's page: what needs you, what's working, and what's done. Give the Agent a task from here.

Thread

One piece of work. It runs in the background and brings its Result back to Home.

Project

A folder on your Mac that your Agents work in.

Runtime

The coding agent that does the work in a Thread: Claude Code, Codex, OpenCode or Antigravity.

Result

The summary a finished Thread brings back to Home.

Groupie

Several Agents on one task, each taking the part it suits best, for a better result than one alone.

1. In an Agent's Home, write the task in the box and send it. That starts a Thread.
2. The Thread shows in Home with its live status while it runs. You can carry on with something else.
3. When it's done, its Result lands in Home: what changed and what to look at.
4. Open the Thread to watch, steer or stop it, review its Changes, or use its terminal.

Home never does the work itself. Every reply lives in a Thread, so you can always trace a change back to the task that made it.

Each coding agent keeps its own sign-in and the plan you already pay for. There's no Custard account. Pick a Runtime per task, or let the Agent use its usual one. Custard records which Runtime and model did each piece of work.

Claude Code

Anthropic's Claude models, on your Anthropic API key. Paste the key in Settings; Custard keeps it in a file only you can read.

Codex

OpenAI's models, on your ChatGPT or OpenAI sign-in.

OpenCode

Models from any provider you've signed in to through OpenCode.

Antigravity

Google's Gemini models, on your Google sign-in.

A Groupie puts several Agents on one task, each taking the part it suits best, for a better result than one alone. Start one like any other task: pick who's in it and who leads, then write one prompt.

1. The lead plans the job and hands out the parts.
2. Each Agent builds its part at the same time, in its own copy of the Project, on its own Runtime.
3. Custard brings the parts together and runs your tests itself.
4. You get one set of Changes to review, with who did what. Your Project isn't touched until you apply them.

A Groupie needs a Project that's a Git repository. Use one when a job has a few parts, or you'd like a second pair of eyes. For quick things, one Agent is plenty.

Custard runs on your Mac, next to your code. Your code and file paths stay there. The only traffic to a model goes through the coding agent you picked, straight to its own provider. There's no Custard cloud in the middle.

Custard stores one secret, your Anthropic API key for Claude Code, in a file only your user can read. Every other sign-in stays with its own coding agent.

Checking on your Agents from your iPhone is built and being tested on real devices. It arrives once it's proven. Windows and Linux aren't planned yet.