[manuisin]

A while ago, I used this library called ts-interface-builder to generate runtime validation functions from TS types. It worked really well, I was able to use the types from my front-end without any modifications for back-end validation.

Also, used the inferred response types from endpoint functions and passed them back to the front-end to use with front-end fetch calls. This was probably the biggest improvement in terms of productivity and improving accuracy. Imagine every time you change an endpoint's response, any fetch calls that are impacted would just show errors at compile time/in your editor.