What's a senior engineer's job?
One thing that I consider to be a really important part of a senior engineer's job that's not enumerated here is: helping more junior engineers come up with estimates for difficulty and time on projects they're about to undertake. To a senior engineer, there are a large number of projects that are fairly easily scope-able, e.g. "add a new API endpoint"; "refactor this medium-large model" that a junior engineer may not have the necessary degree of confidence to estimate. While this can sometimes be the responsibility of an engineering manager, not all EMs are sufficiently technical to know how long it'll take a _junior_ engineer to take on an otherwise easily-scoped task.