I've always pushed back against "all IP even on my own time with my own equipment." You're right that it's common in tech employment, but it's never been a deal-breaker for me.

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edited to elobrate You can almost always reach a compromise if you aren't a jerk about it and can show you understand the company's concerns. Typically I have it modified so that if I'm using their resources at all (office, computer, pen they bought me, etc.) it's theirs. Or if it's directly related to their core business it's theirs. Note that this is separate from a non-compete.

The key thing is to find some clear dividing criteria that is 1. generous to the company and 2. within my control (like choosing to use my own machine). Same idea behind the "one person cuts, the other chooses" method of dividing a cake.

I'm never going to give a company all of my output carte blanche. I want to contribute to open source. I want to make little (unrelated) fun things on my own and not worry about being sued if it ends up becoming popular. The company has a reasonable fear of people competing against them while on their payroll. Both sides can reasonably expect some protection.

In the past, when I’ve tried to politely push back against these, the response has always been a firm “sign the agreement unmodified or GTFO.” When your employer has 500 lawyers, you do what they say or get back to the job hunt.

Yeah, if they're not going to let me have any say in matters that directly affect my ability to put food on the table for my family then I'm glad to walk. If your prospective manager isn't willing/able to go to bat for you on things like this it's a good bet they're not going to be willing/able to go to bat on lots of other things that matter while you are there. Not worth it.

Or, if they really are your only option at the moment, you can also sign with the intention of claiming you did so under duress if sued, but I'm not sure I'd be comfortable with that.

It's all about bargaining power

These "IP agreements", in my experience, include an "Invention Disclosure" section where you can submit a list of "inventions" that you developed before you took the position. It's supposed to be the blacklist of stuff explicitly excluded by the IP ownership agreement (i.e., you still own it since you "invented" it before you joined the org). Usually they give you a few lines to write these in. My approach has been to provide this as an attachment with an exhaustive list ranging from things I've actually developed all the way to mere ideas that could be realized in some form. Of course, every new time you have to sign one of these, the list should be longer. Each item should be broadly written; they can't be asburdly broad, like "Software to perform transformations on data", but you can undoubtedly find ways to make the item more specific to certain domains, and write in that annoying "cover your bases multiple times" form of legalese, e.g. "Tools, methods, and approaches in distributed and monolithic data aggregation, satisfying static and dynamic reliability constraints".

I reliably hear from HR or contracts that I'm the only one they've seen fill that section out, and certainly to the length I typically provide, but they duly accept it and execute the agreement. I've never seen them send to an IP lawyer or anyone else to screen the list for legitimacy.

Considering how challenging litigating technical IP claims is, I think this should have some amount of reasonable deterrent effect regarding threats or actual wanton IP theft litigation after leaving the org's employ.

In California, it is flat out illegal for an employer to claim stuff you've created using your own equipment on your own time. As it should be.

Many believe this is one of the reasons Silicon Valley became what it is.

...illegal, but with a loophole you can drive a truck through: if the employer thinks your project is close enough to what they do (or might one day do) it’s theirs. Beware!

But they have to prove this to a judge. The onus is now on them to prove that the thing is related enough to keep you from feeding your family.

I agree, but it’s you vs 500 lawyers. The company can afford litigation, can you?

Again, that loophole you cited is nowhere near as large as you think it is. Otherwise it would constantly be used.