I did something similar a year ago at the company which I work, I basically wrote a middleware that intercepts all the requests(express JS) and writes to a Open

I did something similar a year ago at the company which I work, I basically wrote a middleware that intercepts all the requests(express JS) and writes to a OpenAPI YAML file. It diffs previous requests to see which parts of the request path could be variables. The system isn't perfect but you are 95% there which is better than having no documentation or to hand write documentation or keep that spec file updated with changes that people introduce in the code. (got promoted to tech lead after this :-) )