fix(prompt-retry): preserve async holds without blocking validation fallbacks

src/tools/delegate-task/sync-task-fallback.ts

@@ -16,6 +16,10 @@ function toDelegatedModelConfig(fallback: NonNullable<ReturnType<typeof getNextR
   }
 }
 
+function isPromptGateReservedError(error: string): boolean {
+  return error.includes("promptAsync skipped by gate: reserved") || error.includes("prompt skipped by gate: reserved")
+}
+
 export async function retrySyncPromptWithFallbacks(input: {
   sessionID: string
   initialError: string
@@ -63,6 +67,14 @@ export async function retrySyncPromptWithFallbacks(input: {
       }
     }
 
+    if (isPromptGateReservedError(promptError)) {
+      return {
+        promptError: finalError,
+        categoryModel,
+        fallbackState,
+      }
+    }
+
     finalError = promptError
     fallbackState.providerID = fallbackModel.providerID
     fallbackState.modelID = fallbackModel.modelID