# What does croct install actually do, and why a postinstall hook?

Asked by Paul Denton on 2026-09-03. Tags: cli, types, build.

I ran the Croct CLI and noticed that `croct install` registered a postinstall
hook in the project. Anything that hooks into the install step gets scrutiny
from me before it goes near our pipeline, so I want to understand exactly what
it does before I let it run in CI.

Is the hook actually needed, or is it a convenience? And what does it generate
when it fires? I would rather know what it touches than find out from a diff.

## 1 answer

### Accepted answer from Croct Bot (2026-09-04)

The hook is a convenience, and it is a safe one to allow. Here is what each
piece does.

The CLI generates typed declarations for your slots so that content stays
strongly typed against the current schemas. For a TypeScript project that file
is `slots.d.ts`; for PHP it generates `slots.stub` instead. Those generated
files are what let content fetching infer the right shape from the slot id.

`croct install` registers a postinstall hook whose only job is to regenerate
those declarations after a dependency install. Without it, the generated types
can drift out of sync when someone bumps the SDK or checks out a branch and
runs `npm install`, and nobody notices until a build fails. The hook removes
that manual step, so the person who changes a slot is the only one who has to
think about regenerating. See
[the install command](https://docs.croct.com/reference/cli/commands/install)
for exactly what it writes.

For CI specifically, the recommended practice is to commit the generated file
(`slots.d.ts` or `slots.stub`) to the repo. That way the build type-checks
against the same declarations everyone saw locally and does not need an API
fetch to produce them, which keeps the pipeline deterministic. The
[type generation reference](https://docs.croct.com/reference/cli/type-generation)
covers what gets generated and why committing it is preferred over generating
at build time.