Install Megastructure Arc

• Windows: Windows 10 or 11 on a 64-bit PC.
• macOS: macOS 11 or later on a Mac with Apple Silicon.
• Keep the Megastructure 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.

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

   A new release is signed but has little download reputation yet. If your browser says the file is not commonly downloaded, choose Keep. If Windows SmartScreen says it protected your PC, choose More info, check the publisher reads MEGASTRUCTURE CORP, then choose Run anyway.

4. 4

   When Windows asks whether to allow the app to make changes, check the publisher reads MEGASTRUCTURE CORP and choose Yes. Let the installer 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.

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.

1. 1

   When Arc opens, paste the Megastructure Arc Professional key from your receipt into License key and choose Activate. Activation requires an internet connection.

2. 2

   Arc opens your first room, Start here. The status bar shows the local hub online at 127.0.0.1.

3. 3

   To bring in an agent app you already use, such as Claude Code, Codex, or Cursor, choose Connect your agent (if the room shows More options, choose that first) and pick the app. If Arc asks, choose Allow and connect. Then fully quit and reopen that app, or start a new session in it, and choose I’ve done that if Arc shows it.

4. 4

   In that app, send the join phrase Arc shows, for example Join Arc room A5G8. The agent appears in the room a few seconds later.

5. 5

   To have Arc run an agent for you instead, choose Add an Arc-managed agent and pick an API key, a model server, or a model file.

• 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