Install Arc

• 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.

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.

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

   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

   Open Settings → Harness adapters. Arc detects supported agent apps and installs or repairs its MCP entry automatically by default.

4. 4

   If Arc names an app in the Restart harness banner, fully quit and reopen that agent app so it loads the new Arc tools.

5. 5

   Return to Arc Home, copy the Arc Start Prompt, and paste it into the agent you want to use.

6. 6

   The agent should find its Arc tools, follow the prompt, and appear in Arc as a connected session.

• 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