How do I know if I'm good at programming?

Coding is not enough. Is your code maintainable, interoperable? Did you ship?

What are the priorities of the project? Is your code formally verified not to have bugs? ETH just had such a bug. Has it been tested at scale? Twitter used to have fail whales.

Does your product have a community? Do you manage teammates well?

People live lives, companies build products. Ask yourself, "is my company building a good product?"

To me, someone who is "good" is just someone who has learned the language and main paradigms / tools for it, and can pick up new stuff fast. It's like a native speaker of English who can understand what you're saying and write a book on a new topic that goes over well.

Good means less bugs, maintainable code and playing well with others.

The first is the “rockstar” developer type who is great at prototyping, hitting deadlines no matter what and delivering functionality, albeit full of bugs. They will write 80% of the code and will drive the support team up the wall by breaking the build, causing customer issues in production, security holes and basically seriously degrading the code base. But their boss will love them because they deliver the shiny when required.

The second type are the ones who can sort out the mess created by the first type without making things even worse. They tend to be less visible, less well paid and less in demand but every company needs them.

The whizz kids and the grown-ups basically. Companies who only have the first will burn bright but not be able to scale. Companies who have only the second type tend to move too slowly to get to market or pivot.

So ideally there is a symbiotic relationship between the two types and someone who is a combination of the two is very rare indeed, because the first either needs an ability to place limitations on awareness of the big picture (and it’s very difficult to create a blind spot on demand once you have experience) or they need to be incredible at both analysis and full stack execution. Those people are few and far between so a process that gets the best out of the two types is, in my experience, the way that most companies work.