Type-safe clients and testing
Build a typed RPC client
Infer a client from route definitions and understand the repository and compilation boundaries that make it work.
9 minute lesson
A client in the same workspace gets typed paths, inputs, and outputs from the exported app type. That contrast gives us something useful to test instead of a rule to memorize.
Hono RPC shares TypeScript knowledge between server and client; it is not runtime validation and does not help an unrelated untyped consumer automatically. The useful target is not encyclopedic coverage. Make one deliberate choice, observe its consequences, and know which requirement would make you revise it.
The happy path can hide a bad design: you can publish a server-only runtime bundle to the browser merely to obtain types and still get one successful demo. Push past the demo. export type information cleanly, keep runtime dependencies separate, and preserve server-side validation, then test the condition most likely to prove the choice wrong.
The module is moving toward one outcome: Test the real Hono app and use inferred clients without pretending compile-time types validate network data at runtime. Save the before-and-after evidence now; it will make the final project review much more honest.
Create a typed client call, then send malformed raw HTTP to prove the server still rejects it. Save the evidence, then explain which requirement would force you to choose a different design.
Lesson completed