About 15 years ago I worked on a command line shell that was adding a remoting feature which would allow you to execute a shell command on a remote machine. When the first cut of this came out, it seemed like it worked fine, but I decided to try it across a high latency connection - specifically setting up an inbound connection to the public internet and routing it from our office in the US to a proxy in Hong Kong and back. It performed about like a connection over a 300 baud modem. So I spent a weekend furiously creating a private build that reduced the number of handshakes and added streaming compression that ultimately increased the throughput by something like a factor of 20. On Monday I shared this work with the extended engineering team, and...crickets. I was just a tester after all, you know. The perf was improved after that, but nobody acknowledged the real world testing I'd done, much less the analysis and POC dev work. But flash forward a few years, and my career has progressed. Suddenly I am a manager in a performance review meeting where the promotion of someone I used to work with was up for discussion. I sat across the table from the person's boss when he capped off his argument for promotion with (paraphrasing), "and let's all remember, this is the genius who figured out we needed to add compression to our remoting stream."

"Imitation is the sincerest form of flattery"

Welcome to the club. As one that has been building entire enterprise platforms and adding unique features and functions for decades my vast experiences reflect that there will never be a shortage of people looking to claim others work as their own, even steal it to start another company as this happens very frequently yet just does not get as much attention as it should I believe. I have experienced this at every level even down to one claiming to have built and architected an entire company's systems which was entirely my own effort. I also have direct experience with developers stealing I.P. and starting "new" companies, being discovered, sued, losing the suit and then having their wages garnished for millions in restitution. This is sure to happen more and more as technology is built into all devices needed or not and thus business opportunities increase allowing others to apply those stolen ideas. There are A LOT of narcissist egotists out there and I would encourage everyone to avoid them at all costs as they are toxic to business.

If he took the implementation with him to Apple that's IP theft. Did you mention this to legal at your employer? They might have a case there.

Maybe we should have. This was well over a decade ago now. It wasn't something we could easily prove either. We just had strong suspicions based on the timing and his behavior.

It wouldn't surprise me at all. One of the things that we check for during technical DD is to ensure that all of the IP the company claims as theirs really is theirs. Large dumps of code into a repo just after incorporation or just after a new hire are pretty suspicious and require an explanation, such an explanation isn't always available.

Good team leads / code reviewers / laywers can be real assets because they will stop such a thing before it gets to the stage of doing significant damage to the company.

If you have a 1000x programmer on your team you may have a problem (or you've hired Fabrice).

Copyright lawsuits have one interesting property: the statue of limitations starts when you first became aware of the infringement, not when the deed was done. So you may still have a case, even today, because technically you are still unaware that the infringement happened, it may have happened, but you have no proof. If such proof ever surfaces then that would be the point in time to trigger the suit, and such proof can be obtained through the weirdest channels.

I once became aware a company had been started by an ex employee based on a large body of code that I wrote, and through sheer chance I found a tiny sliver of really hard proof. That's what set the ball rolling.

In case any case any readers don’t know who “Fabrice” is: https://en.wikipedia.org/wiki/Fabrice_Bellard