Judge a machine root-free only on a positive, fresh measure, and believe a verified sender only there (hq ADR 0259 §8, review H2/H3)

The agent-root probe read the sudo module's answer, given in the machine's runtime as the very account
an agent could become, and took a missing account, a missing answer or no accounts as a pass. One
judgement now decides: the machine names an agent account its node-engine judged unable to become
root within 15 minutes (agentConfined, mesh-controller #164), and the login shell's execute is not
served there; anything not read is not free. The probe raises agent-root on it, the new root-free
verb answers it live for the router, and a push composes verified-sender for a kind only while its
machine and the router's pass it.

cmd/mesh-controller/seatverbs.go

@@ -282,6 +282,8 @@ func (a *verbArguments) commandLine() ([]string, error) {
 		return nil, errors.New("tools is answered from the records, not by a command")
 	case "dead-letters":
 		return nil, errors.New("dead-letters is answered by the serving controller, on its own connection, not by a command")
+	case "root-free":
+		return nil, errors.New("root-free is judged by the serving controller, on its own connection, not by a command")
 	case "status":
 		return []string{"status", "--json"}, nil
 	case "nodes":
@@ -1093,6 +1095,9 @@ func seatToolHandlers() (map[string]link.ToolHandler, []string, error) {
 				if verb == "dead-letters" {
 					return deadLettersAnswer(ctx, a)
 				}
+				if verb == "root-free" {
+					return rootFreeAnswer(ctx, a.given["machines"], rootClock())
+				}
 				if verb == "doctor" {
 					// From the serving controller, which runs the self-check and hears the signals
 					// (novox/hq to-be 45 §4): the last verdict at once, or a run now.
@@ -1183,7 +1188,10 @@ func actsOnAPlan(args map[string]any) bool {
 var inProcess = map[string]bool{"tools": true, "calls": true, "doctor": true,
 	// What a consumer gave up on, read and changed on the serving controller's own connection (novox/hq
 	// issue 330).
-	"dead-letters": true}
+	"dead-letters": true,
+	// Whether a machine is root-free, judged live on the serving controller's store and connection (novox/hq ADR
+	// 0259 §8): the router asks it before an approval.
+	"root-free": true}
 
 // answersFirst is a command line whose caller is answered before it runs: a push, by its verb or
 // through `command`. A push sends the machine holding the bus first when its user list changed, the