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/status.go

@@ -302,6 +302,19 @@ func printStatus(asked answers) error {
 		fmt.Printf("\n  `assign <node> <holder>` meets it; reported until every machine has its holders, then refused\n\n")
 	}
 
+	if len(asked.overflowing) > 0 {
+		// **Reported, and the provider still pushed** (novox/hq ADR 0225, issue 263). Each is left
+		// out of its provider's grants, so the module holds a login nothing created; the provider's
+		// machine is sent everything else rather than refused for one consumer elsewhere.
+		fmt.Printf("%d module(s) identified too long for a provision they require, and not granted it:\n",
+			len(asked.overflowing))
+		for _, o := range asked.overflowing {
+			fmt.Printf("  %-12s %-20s %-22s %q is %d, %s keeps %d\n", o.Consumer, o.Module, o.Provision,
+				o.Identity, len(o.Identity), o.Bound.In, o.Bound.Max)
+		}
+		fmt.Printf("\n  a shorter `slug` in the module's definition fits it; `module check` refuses one before merge\n\n")
+	}
+
 	if adopted := adoptedNodes(nodes); len(adopted) > 0 {
 		// Said, because nothing forces the flip: a node left adopted is visible here rather than
 		// read as converged (novox/hq ADR 0100). Not a fault, so it does not break "all well".
@@ -419,6 +432,10 @@ func theThreeQuestions(ctx context.Context, open *stores) (answers, error) {
 			return answers{}, err
 		}
 		out.unheld = append(out.unheld, plan.Unheld...)
+		// And which of its modules a provider leaves out of its grants, for an identity too long
+		// for what the provision keeps (novox/hq ADR 0225) — judged from the consumer's own
+		// resolution, as the provider's composition judges it.
+		out.overflowing = append(out.overflowing, plan.Overflowing()...)
 	}
 	// And every consumer a provider says it keeps failing (novox/hq ADR 0224). Read from what the
 	// providers announced: nothing else in the mesh knows whether a provision is being made.
@@ -538,7 +555,7 @@ func untakenModules(ctx context.Context, inv *inventory.Inventory, nodes []inven
 func (a answers) well() bool {
 	return len(a.wrong) == 0 && len(a.quiet) == 0 && len(a.behind) == 0 &&
 		len(a.waiting) == 0 && len(a.refused) == 0 && a.network == "" && len(a.untaken) == 0 &&
-		len(a.filtered) == 0 && len(a.unheld) == 0 && len(a.failing) == 0
+		len(a.filtered) == 0 && len(a.unheld) == 0 && len(a.failing) == 0 && len(a.overflowing) == 0
 }
 
 // hostSplit is which machines report which host version, for every version more than one machine