feat(release): add reversible production cutover gates

apps/api/src/canary-runtime.ts

@@ -10,8 +10,11 @@ export interface CanaryRuntimeEnvironment {
   readonly CANARY_PORT?: string;
   readonly CANARY_UPSTREAM_PORT?: string;
   readonly MULTI_SIMADMIN_GATEWAY_TOKEN?: string;
+  readonly MULTI_SIMADMIN_CUTOVER_ACK?: string;
 }
 
+export const PRODUCTION_CUTOVER_ACK = 'I ACKNOWLEDGE MULTI-SIMADMIN OWNS PORT 8788';
+
 function environmentPort(value: string | undefined, name: string, fallback: number): number {
   if (value === undefined || value === '') return fallback;
   const port = Number(value);
@@ -41,3 +44,15 @@ export function readCanaryRuntimeOptions(
     gatewayToken,
   });
 }
+
+export function readProductionGatewayRuntimeOptions(
+  environment: CanaryRuntimeEnvironment,
+): CanaryGatewayOptions {
+  if (environment.MULTI_SIMADMIN_CUTOVER_ACK !== PRODUCTION_CUTOVER_ACK) {
+    throw new Error(
+      `Production gateway requires MULTI_SIMADMIN_CUTOVER_ACK=${PRODUCTION_CUTOVER_ACK}`,
+    );
+  }
+  const options = readCanaryRuntimeOptions({ ...environment, CANARY_PORT: '8788' });
+  return Object.freeze({ ...options, ownsProductionPort: true });
+}