Use reverse-domain capability keys
A capability key does not match reverse-domain format (e.g. dev.ucp.shopping.checkout).
Why it matters
Capability namespaces use reverse-domain identifiers to avoid collisions when stores extend the spec. "checkout" is ambiguous; "dev.ucp.shopping.checkout" is unambiguous.
Show fix
"capabilities": {
"dev.ucp.shopping.checkout": [...]
}
