feat(provider-contract): define materializable L2 graph blueprints

packages/external-provider-contract/providers/gelios/v8/package.mjs

@@ -138,7 +138,7 @@ value.collectionProfiles.push({
     maxCurrentEntities: 5000,
     onExceed: "require_partitioned_data_product",
   },
-  retry: { maxAttempts: 4, backoff: "exponential_with_jitter" },
+  retry: { maxAttempts: 4, backoff: "fixed_delay", delayMs: 2000 },
 });
 
 value.dataProducts.push({
@@ -232,6 +232,13 @@ value.l2Templates.push({
   ],
 });
 
+// The target Engine runtime materializes bounded fixed-delay retries exactly.
+// v8 therefore avoids promising a backoff algorithm that n8n cannot execute.
+value.collectionProfiles = value.collectionProfiles.map((profile) => ({
+  ...profile,
+  retry: { maxAttempts: 4, backoff: "fixed_delay", delayMs: 2000 },
+}));
+
 export const geliosProviderPackageV8 = deepFreeze(value);
 
 function optional(type) {