# Do the generated slot types actually catch schema changes at build time?

Asked by lucas_ts on 2026-08-16. Tags: vue, typescript, dx.

I committed the CLI-generated slots type file and I want to confirm the
behaviour I am hoping for: if a component schema changes, does my Vue build fail,
or will it happily ship a slot render that is quietly broken against the new
shape?

I am trying to decide whether to trust these types as a real safety net or just
treat them as editor hints. Which one is it in practice?

## 2 answers

### Accepted answer from marek_ts (2026-08-17)

Real safety net, as long as you type the fetch against the slot. The CLI
generates a `slots.d.ts` describing each slot's content shape, and if you
annotate the fetch with that slot type, a mismatch between what your component
reads and what the schema now produces surfaces as a type error at build rather
than at runtime.

We lean on this in CI. The generated types caught a schema change before it
ever hit prod, best DX I have had for CMS personalization. Someone bumped a
component, regenerated the types, and the build went red on the components that
still read the old field. Nothing shipped broken.

### Answer from hanna_k (2026-08-18)

One thing that makes this smoother: commit the `slots.d.ts` file. If it is in
version control the build type-checks against it directly and does not need to
hit the API at build time to know the shapes, which keeps CI hermetic and fast.

Pair that with pinning the slot version in your fetch so the committed type
matches exactly what the code expects. If you leave the version off, the type
and the runtime schema can drift apart and you lose the guarantee you are asking
about.

#### Reply from lucas_ts (2026-08-19)

That is what I wanted to hear. Types committed, versions pinned, fetch
annotated. Treating them as the guardrail from now on.