Say the terminal explicitly, only from a login session, and name the unannounced pull request (hq ADR 0272)

- commandEnvironment takes the terminal as a bool instead of reading an
  empty verb as one; every non-terminal line names its verb and is stripped
  of MESH_CLI_TERMINAL, and a test with the mark set in the serving
  environment fails when that strip is taken out.
- On the control-node the operator's account is the terminal only from a
  login session, as the node-engine reads it from the kernel's cgroup; the
  tool runner and the account's user units run as the operator too, and are
  ordinary calls. The request carries `session` (field-name tests on both
  sides).
- A pull request the forge never announced is named with its number in
  the condition's headline (hq issue 347), from the stalled line's
  `number`, which mesh-delivery sends.

cmd/mesh-controller/meshcli.go

@@ -71,8 +71,14 @@ func judgeCLI(node string, asked link.CLIAsked, nodes []inventory.Node, control
 			"terminal is the one control-node's operator account", len(control))}
 	}
 	if control[0] == node {
-		return cliVerdict{terminal: true, why: fmt.Sprintf("the controller's terminal: %s on the control-node %s",
-			asked.Account, node)}
+		// **A person at a terminal, not a service of the operator's** (review of ADR 0272): the tool runner and the
+		// account's user units run as the operator too, and only a login session is the terminal.
+		if asked.Session == "" {
+			return cliVerdict{why: fmt.Sprintf("not the controller's terminal: %s on %s asked from no login session — a "+
+				"service or a user unit running as the operator, not a person at a terminal", asked.Account, node)}
+		}
+		return cliVerdict{terminal: true, why: fmt.Sprintf("the controller's terminal: %s on the control-node %s, "+
+			"login session %s", asked.Account, node, asked.Session)}
 	}
 	return cliVerdict{why: fmt.Sprintf("not the controller's terminal: agents on %s may run as %s, so a "+
 		"terminal-only change is made from the control-node %s (novox/hq ADR 0272)", node, asked.Account, control[0])}
@@ -148,7 +154,7 @@ func runForMeshCLI(ctx context.Context, node string, asked link.CLIAsked, v cliV
 		verb, line = cliVerb, composed
 	}
 	cmd := selfCommand(ctx, line)
-	cmd.Env = commandEnvironment(fmt.Sprintf("%s through mesh-cli on %s", asked.Account, node), verb)
+	cmd.Env = commandEnvironment(fmt.Sprintf("%s through mesh-cli on %s", asked.Account, node), verb, v.terminal)
 	// No standard input: a command that reads one gets nothing, and fails saying so (ADR 0272 §5).
 	cmd.Stdin = nil
 	var stdout, stderr bytes.Buffer