> My partner has ~300 tabs open at any point in time

I'm like this, though more so. I have hundreds of tabs open on my main desktop, a few tens on my laptop, and [deity] knows how many “open” on my phone. It is an effect of my disorganised thinking: I flit to something else and leave the tabs open for when I get back to this train of thought. Sometimes I spend some time going through them, discarding old ones that are unlikely to ever be relevant, collecting others into notes elsewhere (usually the bunch of text files I maintain for ideas/project/etc, bookmarks don't cut it with or without extensions) and leaving the rest for the next cleanup session once I get bored with the review process.

I really need to sort a proper note taking/keeping process and stop working this way though, the browser isn't the right place for it beyond the short term. I've tried various ways (extensions and such) to help with organising tabs, but none have worked any better for me in the end (the more complex ones just end up adding a level of extra work to reorganising later). Horse looks interesting, like an extension I've tried and liked but that extension had too many rough edges, though I'm not paying $20 just to try it!

As well as the organisation aspect, the other reason I want to get this sort of state management out of the browser is that all that state is locking me in a bit. Moving to a different browser doesn't solve that, I don't want to just import it all wholesale into a new one because that'll solve nothing in the backlog and I'll just do it again at later date. Chrome losing some windows occasionally after an update, or a couple of times in recent months after falling over (at least twice something in a facebook tab seems to have killed it, then when restarting that window, all the tabs in it, and some tabs/windows that were opened from facebook, don't get restored) has been a useful push towards finally making some effort to move to Firefox, but again I really want to go back to using the browser as a browser and managing research/work state elsewhere. I now have tens of tabs open in FF as well as the great many in Chrome…

Basically: I think I have an illness and tabs are enabling it :)

> Then the remaining question is, can a single product solve both user behaviors?

Probably not, the complexity required for one set of behaviours just makes it burdensome for those with simpler needs, so trying to solve both problems leads the app to needing to support to distinct but related feature sets. Especially for people like me who have multiple devices and don't want to simply sync the state between them for various reasons.

The extension model sort-of works better for this: let the main app deal with the basic needs most users have, and extensions deal with those of us who want/need something more. If only there were extensions that worked exactly the way I need/want (that there are so many options, and none of them look ideal to everyone so more are popping up all the time, tells you how varied the needs/desires are amongst people).

> Or do you need a new product to solve for the second behavior?

I think the issue is that the browser isn't the right place for this much context. It should (IMO) be how you look at the information, not how you organise it. Like my TV views my media archive via Kodi, but I organise it elsewhere (on the PC/laptop). But it is so convenient to leave a little context in tabs/windows/history, and you only discover how inconvenient it eventually becomes once you are deep into the rabbit hole.