Insequent
It works very well now, and the Android client is pretty great too, but there are still some gaps. Mainly, the surrounding ecosystem is quite sparse, e.g.: - There is basically only a single web client for it (node-based, which is a con from my perspective) - There are only a handful of semi-functional log searching/browsing utilities around
IANAL, but I'm fairly certain that essentially means "anything we require you to introduce is specifically defined to not be a systemic weakness". What do we need reality for when we've got doublespeak?
Apple have already essentially stated they will not make use of Aus tech products if this goes through, as have a few other big players. I'm not sure if EU companies will be able to use Aus tech products and also comply with the GDPR, so there's a rather large chance that our nascent tech industry immediately implodes.
Although: I once investigated a soft freeze on a realtime-patched Linux system that turned out to be caused by a vendor's software somehow managing to indefinitely stall an RCU grace period, eventually consuming all available memory on the system. The kernel core dump being over 4GB in size was a bit of a give-away.
Why? If the user already has a malicious 'external application' running on their system with sufficient privileges to do any of this, then they're already screwed, and they have bigger problems to worry about than malicious WebExtensions.
More generally, I don't think we should hold applications responsible for the security or behaviour of parts of the software/hardware stack at equal or higher privilege level to them, including other applications. Mostly because, well, they can't do anything truly effective in that regard.
I see you're worried about average users unknowingly installing random malicious crap, and I've seen a lot of that myself. I think the way forward is pretty much what is being done on mobile platforms currently: universally applied application sandboxing, usage of existing fine-grained access control models (and also the development of ones that are saner to use), and better communication to the user about what their applications are doing and what the permissions they are requesting actually mean. Yes, it's still a clusterfuck, but it's an improvement.
A security model involving applications in an arms-war with one another, using increasingly byzantine restictions in an attempt to prevent external manipulation, feels less like something I would want any part of, and more like something out of a dystopian sci-fi novel.
: Although I think Google went too far on the "lock things down completely" side of things when they made it outright impossible to, say, use rsync to backup or sync the entire contents of a phone's sd card to/from the network