mesh-grants publishes only a first or an additive membership, and holds no lock across the bus (review of 1ff5049)

Composed without a root-free judgement, a membership would drop a kind's verified-sender and the
operator's channel approvals would stop being honoured; any loss now stays a shadow difference,
named. A tool no longer waits on a pass's round trip. compose-now says the controller serves no
verb to write a module's grant again.

modules/mesh-grants/cmd/mesh-grants/tools.go

@@ -67,7 +67,8 @@ func toolsOf(p *grants.Part) []stdio.Tool {
 			Run:   func(a map[string]any) (any, error) { return p.Grants(grants.Answer(a, "module")) }},
 		{Name: grants.ToolMembership, Description: "One module's membership on one node (ADR 0547 clause 6): as composed now from the " +
 			"bus's records with the bus composer, and what the part's process published of it at its last pass (published, " +
-			"unchanged, or why not), with what the composition cannot read. Read-only.",
+			"unchanged, or why not: a shadow difference names what publishing would lose), with what the composition cannot " +
+			"read. Read-only.",
 			Input: schema(map[string]string{"node": "the machine", "module": "the module"}, "node", "module"),
 			Run: func(a map[string]any) (any, error) {
 				return p.MembershipOf(grants.Answer(a, "node"), grants.Answer(a, "module"))
@@ -81,8 +82,10 @@ func toolsOf(p *grants.Part) []stdio.Tool {
 			"the part's process (which alone holds the grant to publish a membership) to compose the memberships, the user list and " +
 			"the assertions, publish each membership that differs from the one last published, and keep what changed in its own " +
 			"state (one revision when an input changed, none when not), saying user-list-changed and membership-changed. Answers " +
-			"the ask and the last pass; grants_user_list shows the pass that answers it. The user list, assertions and grants stay " +
-			"in shadow.",
+			"the ask and the last pass; grants_user_list shows the pass that answers it. A membership is published only when it is " +
+			"the first or only adds to the last one; any loss stays a shadow difference, named. The user list, assertions and " +
+			"grants stay in shadow. It cannot ask the controller to write a module's grant again: the controller serves no such " +
+			"verb, and the answer says so.",
 			Run: func(a map[string]any) (any, error) { return p.AskCompose(stdio.CallerOf(a)) }},
 		{Name: grants.ToolAssert, Description: "One module's buckets, logs and streams (ADR 0547 clause 6), composed from its manifest at " +
 			"the indexer's trunk with their limits, beside what the bus holds (through the bus module's nats_streams). In shadow it " +