Bound a consumer's identity by the provision it requires (hq issue 263)

The one global 20-character bound made every consumer pay an object
store's key length, even for provisions that keep no name, and a single
overflow refused the provider's whole declaration. An offer now states
its own bound (identity: {max, in} or false); unsaid, a provider told its
consumers keeps 20 and one told nothing keeps none. module check judges
every identity on the longest machine name before merge, and a provider
leaves an overflowing consumer out of its grants and composes, with the
consumer named by push, plan and status (ADR 0225).

cmd/mesh-controller/check.go

@@ -25,7 +25,17 @@ import (
 // mesh seat is judged fully only at registration. A seat another module declares is unknown unless
 // that module's manifest is passed too. Both are printed as a note, not as a problem — a check that
 // refused what it could not see would teach people to ignore it.
+//
+// **And every identity against every bound it meets** (novox/hq ADR 0225, issue 263): each module's
+// identity, on a machine whose name is `longestMachine` characters, against the bound of every
+// provision it wants that a manifest given here offers. An overflow is refused in the pull request
+// that introduces it — a new requirement, a lowered bound, a longer slug — instead of on the
+// provider's machine when a real machine's name first meets the module's.
 func moduleCheck(paths []string, out io.Writer) error {
+	return moduleCheckFor(paths, catalogue.DefaultLongestMachine, out)
+}
+
+func moduleCheckFor(paths []string, longestMachine int, out io.Writer) error {
 	if len(paths) == 0 {
 		return errors.New("module check <manifest.json>... — one file per module; pass every " +
 			"manifest of a repository together so the rules between them are checked too")
@@ -74,6 +84,15 @@ func moduleCheck(paths []string, out io.Writer) error {
 	}
 	failed += len(problems)
 
+	// Between the manifests too: an identity against the bounds of the provisions it wants, which
+	// only the provider's manifest states.
+	identities := catalogue.IdentityProblems(shelf, longestMachine)
+	sort.Strings(identities)
+	for _, p := range identities {
+		fmt.Fprintln(out, p)
+	}
+	failed += len(identities)
+
 	var names []string
 	for name := range shelf {
 		names = append(names, name)
@@ -109,7 +128,8 @@ func moduleCheck(paths []string, out io.Writer) error {
 	}
 	fmt.Fprintf(out, "%d manifest(s) checked. Judged against the seats this binary carries; a claim on "+
 		"one of the mesh's own seats is judged fully at registration, and a seat declared by a "+
-		"module not given here reads as unknown\n", len(paths))
+		"module not given here reads as unknown. Identities judged on a %d-character machine name, "+
+		"against the bounds of the providers given here\n", len(paths), longestMachine)
 	return nil
 }