Arc setup guide

Install Arc

From signed installer to a connected agent. No Python, Docker, account, or cloud workspace is required.

Before you begin

  • Windows: Windows 10 or 11 on a 64-bit PC.
  • macOS: macOS 11 or later on a Mac with Apple Silicon.
  • Keep the Arc Professional license key from your Lemon Squeezy receipt available for activation.
  • Close any older Arc installer before starting. Your agent apps can remain open until Arc asks you to restart them.

Windows installation

Arc ships as a signed 64-bit Windows setup application.

  1. 1

    Open your Lemon Squeezy receipt or My Orders and download the current Windows installer.

  2. 2

    Open the downloaded Arc setup file. Confirm the version in the filename matches the current release shown on this site.

  3. 3

    When Windows shows the publisher, verify it reads MEGASTRUCTURE CORP. Publisher identity and download reputation are separate, so a new build may still be described as not commonly downloaded.

  4. 4

    Approve the installer and let it finish. Arc bundles its local hub; you do not need to install Python, Node.js, Docker, or a database.

  5. 5

    Launch Arc from the Start menu or the installer’s completion screen.

macOS installation

The current macOS build supports Apple Silicon Macs.

  1. 1

    Open your Lemon Squeezy receipt or My Orders and download the current macOS DMG.

  2. 2

    Open the DMG and move Arc into Applications.

  3. 3

    Launch Arc from Applications. If macOS shows its first-open confirmation, verify that it identifies Arc as a signed application from Megastructure before choosing Open.

  4. 4

    Arc starts its bundled local hub automatically; no command-line setup is required.

Activate and add your first agent

  1. 1

    Choose Enter license key in Arc and paste the Arc Professional key from your receipt. Activation requires an internet connection.

  2. 2

    Confirm the status bar says the local hub is online at 127.0.0.1.

  3. 3

    Create a project and open a room for your work.

  4. 4

    To run an agent in Arc, choose Add an Arc-managed agent in the room, then select a local model or hosted model connection.

  5. 5

    To connect an existing agent app, open Settings → Harness adapters and confirm its Arc integration is installed. If Arc asks you to restart that app, fully quit and reopen it.

  6. 6

    For an existing agent, copy the join phrase from your Arc room and paste it into that agent. It should appear in the room once it joins.

Updates and restarts

  • Arc checks for updates shortly after launch and every few hours when automatic checks are enabled.
  • Nothing installs silently. Arc shows the version and asks before downloading and installing it.
  • Choose Install and restart. Arc closes and relaunches itself with its local hub; you normally do not need to reboot your computer.
  • You can also use Settings → Updates → Check for updates. If a check fails, download the current installer again and run it over the existing installation.

If anything does not match these steps, use Arc Help before changing security or network settings. Help