nextTab / previousTab (J/K) not working in new Chromium-based OpenAI browser

Description

The Vimium commands nextTab and previousTab mapped to J and K are not functioning in the new OpenAI browser (Chromium-based). Native shortcuts such as Cmd + Shift + [ and Cmd + Shift + ] continue to work as expected, but Vimium does not appear to intercept the keystrokes for J and K.

Environment

• Browser: OpenAI Browser (Chromium build)
• OS: macOS (latest)
• Vimium Version: (latest from Chrome Web Store)
• Reproducible: Yes, across all pages (including normal web domains)

Steps to Reproduce

1. Open multiple tabs.
2. In Vimium options, ensure the mappings are set:

   map J nextTab
   map K previousTab
   

3. Try pressing J and K to navigate between tabs.

Expected Behavior

Vimium should switch to the next or previous tab when pressing J or K, consistent with its behavior in Chrome.

Actual Behavior

No action is triggered. The commands Cmd + Shift + [ and Cmd + Shift + ] (native browser shortcuts) work normally.

Notes

• The issue may be due to the OpenAI browser’s tab isolation or stricter content script permissions preventing Vimium from receiving tab context events.
• Verified that Allow access to all sites is enabled in Vimium’s permissions.

Suggested Next Steps

Check if:

• The OpenAI browser uses a restricted API for keyboard events that blocks Vimium’s tab control.
• Any recent manifest v3 or background page changes affect tab switching commands.

Start by reproducing the J/K mappings in the OpenAI Chromium-based browser and compare them with Chrome, using the listed steps and checking whether Vimium has access to all sites. Investigate keyboard-event handling, tab isolation, and manifest V3 or background-page behavior. Done means nextTab and previousTab reliably switch tabs with the custom mappings, or the browser limitation is documented.