This has been a long time coming, actually, and recent developments just put the final nail in the coffin. I am ending all development and support for my "extension"-type add-ons effective immediately.
This affects (daily user numbers according to addons.mozilla.org):
If anyone is interested in taking over development and maintenance of any of those, please let me know and I'm happy to convert their repositories over to github for easier working with them, and and the new developer to their administration on AMO and/or move them over to you completely.
I will leave them listed on AMO for a little while so people who want to take over can take a look, but I will hide them from the site in the near future if nobody is interested.
The reasons for this step are multiple:
For one thing, I just don't have the time for updating their code or improving them. My job is stressful enough that my head is overflowing with Mozilla-related things all the time, and my employer is apparently not willing to give me any relief (in terms of hiring someone to supplement me) that would give me back sanity, so I need to remove some Mozilla- and software-related thing from my non-work time to gain back a little sanity so that I don't burn out.
I am also really sad that apparently nobody finds the time or energy to make decent managing and notification mechanisms available for UI code around the new-style web storage mechanisms like indexedDB, appCache, or ServiceWorkers caching, while we do have quite nice APIs there for long-standing things like cookies. For getting Tahoe Data Manager (which was my most interesting add-on) to work decently, I would have needed decent APIs there as well.
Then, my interest for experimenting with code has moved more and more away from the browser, which keeps changing around me all the time, and towards actual web development, where existing code doesn't get broken all the time and your code is more isolated. As a bonus, I can develop things that run on my (Firefox OS) phone and that I can show other people when I'm somewhere. And even there, I don't get as much time to dig into stuff as I would like to, see above.
And finally, and that's why this culminates right now, I disagree with some pieces of Mozilla's add-on strategies
right now, and I don't want to be part of that as an add-on developer.
For one, I think add-on signing is a good idea in principle, but not enabling developers to test their code in any way in the same builds that users get is against everything I learned in terms of quality assurance. Then, requiring developers and other users of unbranded (or early pre-release) builds to turn off security for everything just to use/test one or two unsigned add-ons just feels plainly wrong to me (and don't tell me it can't be done otherwise, as I know there are perfectly good ways to solve this without undermining signing and preserving more safety). And I also fear that, while add-on signing brings a lot of pain to add-on developers and will make us lose some of them and their users, we will not reduce the malware/adware problem in the mid to long term, but rather make it worse, as they will resort to injecting binary DLLs into the Firefox process, which is the primary cause of startup crashes on updates, and I will have more grief in my actual job due to this, next to Firefox losing users that see those crashes.
And on the deprecation of "the permissive add-on model" as they call it in the post, I think that the Firefox UI being written in web (CSS/JS/HTML) or web-like (XUL) technologies and the ability to write add-ons that can use those to do anything in Firefox, including prototyping and inventing new functionality and UI paradigms, is the main thing that sets Firefox apart product-wise from all its competitors. If we take that away, there is no product reason for using Firefox over any other browser, the only reasons will be the philosophy behind Mozilla (which is what I'm signed up for anyhow)and the specific reflection of those in some internals of the browser, like respecting privacy and choice a little bit more than others - but most people consider that details, and it's hard to win them over with those. Don't get me wrong, I think that the WebExtensions API is a great idea (and it would be awesome to standardize some bits of it across browsers), and add-ons being sandboxed by default is long overdue. But we also would need to require less signing and review for add-ons that are confined to the safe APIs provided there, and I think we'd still, with heavy review, signing, and whatnot, need to allow people to go fully into the guts of Firefox, with full permissions, to provide the basis for the really ground-breaking add-ons that set us apart from the rest of the world. Even though almost all of the code of my add-ons ran within their own browser tab, they required a good reach into high-permission areas, which probably the new WebExtensions API will not allow that way. But I also do not even have the time to investigate how I could adapt my add-ons to any of this, so I decided to better pull the plug right now.
So, all in all, I probably have waited too long with this anyhow, mostly because I really like Tahoe Data Manager, but I just can't go on pretending that I will still develop or even maintain those add-ons.
Again, if anyone is interested in taking over, either fully or with a few patches here and there, please contact me and I'll help to make it happen.
(Note that this does not affect my language packs, dictionaries, or themes at this point, I'm continuing to maintain and develop them, at least for now.)