===== OnAirScreen: Make OnAirScreen Application executable under macOS =====

<WRAP round tip 60%>
When you download **OnAirScreen** as a `.dmg` from the internet (AstraStudio Customer Portal, our online shop), macOS marks the app with a **quarantine flag**. Gatekeeper then blocks the app on first launch — often with a message like *"OnAirScreen can't be opened because Apple cannot check it for malicious software"* or *"the developer cannot be verified"*.
</WRAP>

OnAirScreen is **not signed with an Apple Developer ID certificate**, so macOS treats every downloaded copy as untrusted until you explicitly allow it.

==== Why is this necessary? ====

  * **Gatekeeper** checks apps before they run.
  * Downloaded files get the extended attribute ''com.apple.quarantine''.
  * Without a trusted signature, macOS refuses to start the app.
  * Removing the quarantine flag tells macOS you trust this copy.

This is normal for unsigned open-source macOS apps — not a sign that OnAirScreen is broken.

==== Remove the quarantine flag ====

**Option A — Terminal (recommended)**

Open **Terminal** (''Applications → Utilities → Terminal'') and run:

<code bash>
sudo xattr -d com.apple.quarantine /Applications/OnAirScreen.app
</code>

Enter your Mac password (nothing appears while typing — that is normal).

Then start OnAirScreen from **Applications** or Launchpad.

**Option B — Finder (without Terminal)**

  - Drag **OnAirScreen.app** from the DMG to **Applications**
  - Right-click (or Control-click) **OnAirScreen.app** → **Open**
  - In the dialog, click **Open** again to confirm
  - macOS remembers this choice for future launches

==== Verify (optional) ====

Check whether the quarantine flag is still set:

<code bash>
xattr -l /Applications/OnAirScreen.app
</code>

If removal worked, ''com.apple.quarantine'' should **not** appear in the output.

==== Troubleshooting ====

**"No such xattr: com.apple.quarantine"**  
The flag is already removed — try launching the app normally.

**"Operation not permitted"**  
  * Confirm the path: ''/Applications/OnAirScreen.app''
  * Use ''sudo'' as shown above
  * On corporate Macs, admin rights or MDM policies may block this

**App still won't start**  
  * ''System Settings → Privacy & Security'' — look for **Open Anyway**
  * Ensure you copied the app to **Applications**, not running it directly from the DMG

<WRAP round tip 60%>
Only remove the quarantine flag for OnAirScreen copies you obtained from a **trusted source** (official website or your own CI build).
</WRAP>