WebLibre Android Browser Extension

[FaFre]

Hi! I am opening this on behalf of a user who requested Floccus support (FaFre/WebLibre#414) for the WebLibre Browser (an Android, Gecko-based browser): https://github.com/FaFre/WebLibre

While I don't have the time right now to build and maintain third-party integrations natively, I could offer a custom or bridged bookmark extension API (likely compatible with the standard desktop API) that Floccus could consume.

Let me know if this is something you'd be interested in and willing to support on your end! If so, I'd be happy to discuss the technical details to make it work.

[marcelklehr]

Hi @FaFre
Thank you for opening this discussion! It would indeed be nice if floccus would work on WebLibre. For now, I'm trying to avoid venturing out of the WebExtensions semi-standard, so a WebLibre specific extension would not be something I'm interested in at the moment. If you can support the webextension APIs that floccus uses (see https://github.com/floccusaddon/floccus/blob/develop/manifest.firefox.json#L22) on the WebLibre side then floccus (along with many other extensions) should work out of the box.

[FaFre]

I did some research and the bookmark API calls that floccus is currently using can be ported/made available — I can patch the engine to make this subset available. Are there any plans to use other bookmark API functionality in the near future, or is the current usage mostly settled?
But I found other issues:

chrome.identity.getRedirectURL() is used in GoogleDrive.ts and Dropbox.ts.
browser.identity.launchWebAuthFlow() is used to run the OAuth flow.

Both are seemingly not exposed by Gecko Mobile, and I would refrain from modifying anything regarding auth flows. Would the extension still work without exposing those calls?

[FaFre]

A few hours later... ;)

I ran some tests syncing via Git with my desktop, and it works in both directions! However, the extension UI has some issues (probably because it was developed exclusively for desktop): For the sync to trigger, you must make at least one local bookmark change on the mobile device. Otherwise, the sync doesn't work (even if the desktop synced changes in the meantime):

2026-06-01 16:00:06.124 29546-29613 WebExtensions           eu.weblibre.gecko.alpha              I  Waiting for service worker readiness                                                              
2026-06-01 16:00:06.126 29546-29613 WebExtensions           eu.weblibre.gecko.alpha              I  Sending message to service worker:  [object Object]                                               
2026-06-01 16:00:06.130 29546-29613 WebExtensions           eu.weblibre.gecko.alpha              E  [JavaScript Error: "Error: Could not establish connection. Receiving end does not exist." {file:  
  "moz-extension://bcef3107-16c1-40ff-9376-c5ad316890a4/dist/js/1188.js" line: 1}]    

Additionally, there are no animations on mobile for actions like pull/push/sync, which is probably related to the error above. I suspect it has to do with extension processes and background workers behaving differently on mobile.

So, based on some rough testing, the bookmark API is working, but the UI needs some polishing for mobile.

You can get the test APK here: https://github.com/FaFre/WebLibre/releases (requires version >= 0.20.0-alpha-6, which is not yet built). The floccus extension can be installed directly via the WebLibre store by switching to Desktop extensions. Btw, WebLibre allows the installation of unsigned extensions (this must be enabled via Settings -> Extensions).

One thing worth noting: Firefox Desktop hides the Mobile/WebLibre root folder by default in the bookmark manager.

cc @TheDidek

[marcelklehr]

This is really awesome! Thank you for working on this! I'll get to work on making the UI mobile ready :)

For the sync to trigger, you must make at least one local bookmark change on the mobile device. Otherwise, the sync doesn't work (even if the desktop synced changes in the meantime)

Mmh, is weblibre perhaps also missing the alarms API?

[FaFre]

I did some research and it seems browser.alarms can only work while the Gecko/WebExtension runtime is alive, but it is not a reliable mobile background scheduler. This might even apply if WebLibre is open but in background = alarms only reliably work if the browser is in use. So it could be possible that scheduled syncs are getting dropped when the browser was not active at the scheduled time. I won't change something here, since this expected behavior on mobile/Android how alarms was implemented (based on my research...). I guess missed syncs could be easily caught during extension initialization by writing down some timestamps.

I found other features that will also not work on mobile:

• History click-count sync is unavailable: browser.history.onVisited in BrowserController.js:137.
• “Sync browser tabs” is not mobile-compatible: LocalTabs.ts uses browser.windows, browser.tabGroups, browser.tabs.move, browser.tabs.group, etc.

The reason is that under the hood different backends are used for mobile/desktop. For the bookmarks API I wrote a kotlin bridge (had as well some code already in place I wrote for WebLibre). The history namespace could be possibly bridged as well, but I would postpone it for now. Sync browser tabs is out of scope for now (WebLibre uses it's own container implementation), it is possible but a major effort. Maybe in the future.

[marcelklehr]

Just committed a patch to make the profile overview responsive :)

[FaFre]

Amazing! Will wait for the next release to test it out