[BUG] MV3 userscript injection fails in active Vivaldi window after session restoration #2711

Environment

• Violentmonkey 2.49.0 (MV3)
• Vivaldi (Chromium 152)
• Debian 13, GNOME

Steps to reproduce
Prerequisite: An enabled userscript matching https://chatgpt.com/*, with Violentmonkey's default injection settings.
Test 1 — Single window

1. Open Vivaldi with chatgpt.com and an active matching userscript.
2. Exit Vivaldi using File → Exit.
3. Relaunch with Startup with: Last Session.
4. The script is crossed out with the warning: "Violentmonkey was restarted. Please reload the tab to run userscripts."
5. Hard reload does not fix it.
6. Open ChatGPT in a new tab — the script runs normally.

Test 2 — Two windows

1. Keep the original window (script inactive) and a new window (script active).
2. With either window focused, select File → Exit.
3. Relaunch with both windows restored.
4. The window active when exiting now has the script inactive; the other window has it active.
5. Repeat with the opposite window active at exit — the inactive state switches accordingly.
6. Waiting 10–15 seconds does not change the outcome.

Additional observations

• Restoring a non-matching website (e.g. Google), then navigating to ChatGPT in the same tab works.
• DevTools captured TypeError: Cannot read properties of undefined (reading 'addListener') in Violentmonkey's injected.js.
• The extension service worker was running normally when inspected.

Expected behaviour
Matching userscripts should run in all restored windows, including the initially active one.

Possible cause (AI-generated hypothesis)
A race condition involving MV3 extension messaging during Vivaldi's foreground-window restoration. However, the evidence doesn't yet identify whether Vivaldi or Violentmonkey is responsible.