[necubi]

Generally getting to senior is much more straightforward than moving past that. In a Google-style system, senior is the terminal level, which everyone is expected to reach. So there should be clear guidelines and a lot of examples of others who have been promoted there.

I can't speak for every company, but generally for a senior promotion you just need to prove that you are a competent developer and can be trusted to deliver medium-sized projects (e.g., 3 developers for a quarter) from design to release without much or any oversight.

If you're not getting those opportunities, you need to talk to your manager about that.

[nullsense]

That seems to be mostly it, though I've found there's a little bit more to it. Namely, not presenting your raw unfiltered thoughts and opinions as much but presenting them through more of a "party line" filter.