A served value may name the consumer it is served to (hq ADR 0188)

${consumer:as} and ${consumer:as:dns} in a serves block are filled per
consumer at resolution, and the one filled value reaches both ends: the
consumer's binding and its ${bound:...} substitutions, and the provider's
contributions entry as `derived`. A fact or alphabet the mesh does not have
is refused at parse; a consumer whose own file already holds the derived
value is refused at resolution, naming the placeholder to write instead.

internal/catalogue/manifest.go

@@ -1360,6 +1360,10 @@ func ParseManifest(raw []byte) (Manifest, error) {
 				"%s serves %q to whoever requires it, and does not provide it", m.Module, to))
 		}
 	}
+	// A served value may be derived for the consumer it is served to (novox/hq ADR 0188). Read
+	// here, where the definition is, rather than when somebody first requires it: a rule that
+	// would be refused at the first consumer is wrong from the moment it is written.
+	problems = append(problems, CheckServes(m)...)
 	for to, where := range m.Binds {
 		if !placedOrAbsolute(where) {
 			problems = append(problems, fmt.Sprintf(