When encoding types for requests like this, I'm exactly as strict as I need to be: no more, no less. Any assumption about the shape of the data that my code will make is encoded in the parser, but the parser is very generous with everything else.
For example, if a request has a field I didn't expect, that's not an error, I simply ignore that field because I obviously didn't need it. Likewise if requests start using a more specific schema, such as now sending only positive integers. If, however, the schema changes such that a field I rely on is dropped or changes type, my code will eventually fail anyway as soon as it makes an assumption about the data. Why not fail at the point of entry instead of saving it for later?
That sounds like it might work. I was commenting based on my experience of people deciding there had to be a single representation for an idea/type no matter what it was used for, across multiple projects and repositories. I was not dismissing appropriate validation at a boundary, just trying to pointing out that, at least in my experience, people get way too wound up about enforcing unnecessary consistency.
For example, if a request has a field I didn't expect, that's not an error, I simply ignore that field because I obviously didn't need it. Likewise if requests start using a more specific schema, such as now sending only positive integers. If, however, the schema changes such that a field I rely on is dropped or changes type, my code will eventually fail anyway as soon as it makes an assumption about the data. Why not fail at the point of entry instead of saving it for later?