mesh-cli lines are calls, followed to their answer; the terminal does not follow assign (review of hq ADR 0272)

- A line ran past the bus's one-minute window for an answer and its answer
  was refused; mesh-cli then said nothing ran of a line that had. Every
  line is now a call (calls.go): answered within AnswerWithin that it is
  running, with its call, and followed by the same account on the same
  node until it ends. Its record keeps the command word only, and its
  answer stays in the memory of the controller that ran it — never on the
  bus, never in `calls`, which answers anyone who may call the seat. Each
  line is said in the journal with its call, who asked where, and how.
- Lines running at once are bounded (8); one over is answered busy.
- An ordinary `settings` line is composed as the settings verb composes
  its own and meets that verb's refusals, the terminal-only keys among
  them, instead of the generic command's blanket refusal.
- The controller's module is assigned and unassigned at the terminal only:
  where it runs is the control-node, whose operator is the terminal.
- mesh.control.*.cli is in the writers table as the machine's own.

cmd/mesh-controller/acts.go

@@ -51,6 +51,9 @@ func assignWith(ctx context.Context, open *stores, node string, opts assignOptio
 	if len(modules) == 0 {
 		return "", fmt.Errorf("assign %s names no module", node)
 	}
+	if err := refusedMovingTheController(modules); err != nil {
+		return "", err
+	}
 	// Held while it is recorded, so it cannot land between a converge's preview and its flip and
 	// be taken without ever having been previewed (novox/hq ADR 0100).
 	ctx, release, err := holdNodes(ctx, open, []string{node})
@@ -209,6 +212,9 @@ func seatDependenciesOnAssign(ctx context.Context, open *stores, node string, mo
 // (novox/hq ADR 0207) — the other side of refusing that module's assignment without one. Several
 // modules in one act are judged together, so a holder and its dependents come off in one command.
 func unassign(ctx context.Context, open *stores, node string, modules ...string) (string, error) {
+	if err := refusedMovingTheController(modules); err != nil {
+		return "", err
+	}
 	if len(modules) == 0 {
 		return "", fmt.Errorf("unassign %s names no module", node)
 	}
@@ -360,3 +366,17 @@ func issueOnAssign(ctx context.Context, open *stores, node, module string) strin
 	}
 	return fmt.Sprintf("its bus credential is issued and sealed to %s, and arrives with the push", node)
 }
+
+// refusedMovingTheController refuses assigning or unassigning the controller's module through a verb (review of
+// novox/hq ADR 0272): the node it is assigned to is the control-node, and the control-node's operator account is
+// the controller's terminal, so whoever moves the module chooses the terminal. At the terminal alone, as every
+// change that says who may change what.
+func refusedMovingTheController(modules []string) error {
+	verb, through := throughAVerb()
+	if !through || !slices.Contains(modules, controllerModule) {
+		return nil
+	}
+	return fmt.Errorf("%s is assigned and unassigned at the controller's terminal only (mesh-cli on the control-node), "+
+		"never through a verb (this came through %q): the node it runs on is the control-node, whose operator is the "+
+		"terminal (novox/hq ADR 0272). Nothing was assigned", controllerModule, verb)
+}