Make it fail (optional but satisfying)

File validation with expectations + attestations

Open:

app/data/items/resources.yaml

Change:

id: 10

to:

id: "oops"

Then run:

npm run attest
npm run check

Now you should see:

• 🔴 failed

With a small, calm error sample like:

Item.id expected integer, got string

This is where it clicks: your files are now governed by declared truth.