fix(gate): F6 approves each CTE by name, not 'phase:6'

reviewer_confirm kind:'cte_result' registered cte_approved --subject
phase:6, which decision_cmd rejects (exit 5) and next_cte never
recognizes — dead-ending F6. Derive the CTE name from 'tht cte next'
(plan-order single source of truth) and approve by name. sql path
(sql_approved:phase:N) unchanged.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

harness/.pi/extensions/tht-gate.js

@@ -620,8 +620,31 @@ export default function (pi) {
 					`CTE plan approvato (${names.length} CTE, sessione ${session}).`,
 				);
 			}
-			if (kind === "cte_result" || kind === "sql") {
+			if (kind === "cte_result") {
-				const dt = kind === "sql" ? "sql_approved" : "cte_approved";
+				// The CTE under review is always next_cte (plan order is enforced by
+				// `tht cte test`). Approve it BY NAME: `cte_approved` keys on the CTE
+				// name (phase.approved_ctes / next_cte); a `phase:N` subject is rejected
+				// by `decision add` (exit 5) and never satisfies F6's advance prereq.
+				const cteName = tht(ctx, [
+					"cte",
+					"next",
+					"--session",
+					session,
+				]).trim();
+				if (!cteName) {
+					return textResult(
+						`Nessun CTE in attesa di approvazione (sessione ${session}).`,
+					);
+				}
+				const err = relayIfThtFails(
+					ctx,
+					["decision", "add", "--session", session, "--type", "cte_approved", "--subject", cteName],
+					"",
+				);
+				if (err) return err;
+				return textResult(`CTE '${cteName}' approvato (sessione ${session}).`);
+			}
+			if (kind === "sql") {
 				const err = relayIfThtFails(
 					ctx,
 					[
@@ -630,14 +653,14 @@ export default function (pi) {
 						"--session",
 						session,
 						"--type",
-						dt,
+						"sql_approved",
 						"--subject",
 						`phase:${currentPhase(ctx, session)}`,
 					],
 					"",
 				);
 				if (err) return err;
-				return textResult(`${kind} approvato (sessione ${session}).`);
+				return textResult(`SQL approvato (sessione ${session}).`);
 			}
 			return textResult(`Approvato (kind=${kind}, sessione ${session}).`);
 		},