A route is a grant, and a provider is told where its consumer is

novox/hq 08-connectivity §3, built. The mirror of a database grant: there the
consumer supplies a name and receives credentials; here it supplies a target
and receives a name. Nothing new in the vocabulary — a route is a provision
like any other.

One field was missing and it is the one that matters for anything reaching
back: a contribution now carries where the mesh says that machine is. A reverse
proxy is told to send traffic to a consumer and has to open a connection, so
without it every provider implementing a provision would have to know how the
mesh names machines — a convention leaking into every module.

The proxy itself is an example, not part of the control plane: the contract is
the file, not this program. It replaces its table whole rather than merging,
because the file is the whole truth about who has a route and merging would
keep serving a name whose module was unassigned — the stale-route fault
08-connectivity lists as open, reintroduced one level down. A name it does not
serve is refused by saying which it does: a route withdrawn and a name that
never existed are different things.

cmd/mesh-control/main.go

@@ -1415,6 +1415,17 @@ func grantsFor(ctx context.Context, inv *inventory.Inventory, node string) ([]ca
 		return nil, err
 	}
 
+	// Where each consumer is, so a provider that must reach back to one does not have to know how
+	// the mesh names machines.
+	shelf, err := inv.Catalogue(ctx)
+	if err != nil {
+		return nil, err
+	}
+	onNetwork, err := whereEveryoneIs(ctx, inv, shelf)
+	if err != nil {
+		return nil, err
+	}
+
 	// What each consumer actually asked for, taken from that machine's own resolution rather than
 	// from a record beside it. A provider told to create a password and not what to create it for
 	// can do nothing with it, and the name a consumer wants is the consumer's to say.
@@ -1432,7 +1443,7 @@ func grantsFor(ctx context.Context, inv *inventory.Inventory, node string) ([]ca
 			return nil, err
 		}
 		out = append(out, catalogue.Grant{
-			Provision: s.Name, Consumer: s.Consumer,
+			Provision: s.Name, Consumer: s.Consumer, At: onNetwork[s.Consumer],
 			From: from, Values: values, Sealed: s.ForProvider})
 	}
 	return out, nil