Introduction

Invariant is where a team follows the work its coding agents do. An agent plans each task, a person approves the plan before any code changes, and a fresh agent reviews the result.

What Invariant is

Invariant is an app for engineering teams who work with coding agents such as Claude Code, Codex or Cursor. It comes in two forms that show the same screens:

  • The desktop app, for macOS on Apple silicon. It runs on your computer and needs no account.
  • The web workspace at app.invariant.guru, for an organisation's members (Pro).

In both, you see your projects, the sessions in each one, what waits on you, and who is working on what.

Your agent works in its own harness

Invariant never launches an agent and never calls a language model. Your agent runs where it always runs: in your terminal, your editor or its own app. You hand it a session by pasting one line that Invariant copies for you. From then on, the agent reports through the invariant command: it says when it starts, writes its plan, ticks each step and writes a summary. The app shows each report as it arrives.

This keeps you in control of which agent works, on which machine, with which settings.

Sessions: planned by an agent, approved by a person

A session is one piece of work. It moves through a fixed path:

  1. You write the task in a few lines, or paste an issue.
  2. Your agent studies the code and writes a plan. In an interactive session it first asks you questions, round by round, until the key decisions are yours.
  3. The plan waits on you. You approve it, or send it back with a note.
  4. The agent builds it and ticks each step of the plan.
  5. The agent writes a summary for you: what changed, how it was checked, what was not tested.

An agent cannot start building before a person approves the plan: the invariant command refuses it. See Sessions.

Reviews: a fresh pair of eyes

When the work is done, you open a review. You paste its line into a new agent conversation, so the reviewer reads the change without having seen the plan. Its findings come back to the app. You keep the ones that matter and discard the rest, and the kept findings become the plan of the fix. See Reviews.

The Brain: what your project knows

Each session leaves a short note on what it learned. The Brain gathers these notes into pages about your project: its architecture, its decisions, its conventions. Agents read the Brain before they plan, so they start from what the project already knows. In an organisation, the team reads and discusses the published Brain together. See Brain.

Packages: shared instructions for every agent

A package bundles instructions, rules, skills and agents. Install one and Invariant writes its items into the files each of your agents reads (Claude Code, Codex, Cursor, Copilot, Aider). Every agent on the project then starts from the same conventions. Packages come from GitHub or from skills.sh. See Packages and skills.

Find your way in the app

The app opens on Projects, the hub that lists every project you work on, in groups. Open a project and the rail on the left leads to its pages:

PageWhat you do thereShortcut
InboxSee what waits on you: a plan to approve, questions to answer, a check-in, a mentiong i
SessionsCreate sessions and follow them on the board, from planning to doneg s
ReviewsOpen reviews and triage their findingsg r
BrainRead what the project knows, and its code mapg b
PackagesInstall packages and skills for your agentsg p
SettingsConfigure the project: agents, plans, reviews, integrationsg ,

Press ⌘ K for the command palette and ? for every shortcut of the page you are on. See Desktop and web and Hub and projects.

Free on your machine, shared in an organisation

On your own computer, everything above is free. Your projects show under This machine, and your work stays in your files.

An organisation (Pro) puts a team's projects online: members see the same sessions and reviews, comment on them, are notified when a teammate mentions them, and can require a teammate's approval on each plan. See Teams and organisations.

Where to go next