diff --git a/src/features/background-agent/types.ts b/src/features/background-agent/types.ts
index 8c384211..795ca89b 100644
--- a/src/features/background-agent/types.ts
+++ b/src/features/background-agent/types.ts
@@ -28,10 +28,13 @@ export interface BackgroundTask {
   progress?: TaskProgress
   parentModel?: { providerID: string; modelID: string }
   model?: { providerID: string; modelID: string; variant?: string }
-  /** Agent name used for concurrency tracking */
+  /** Active concurrency slot key */
   concurrencyKey?: string
+  /** Persistent key for re-acquiring concurrency on resume */
+  concurrencyGroup?: string
   /** Parent session's agent name for notification */
   parentAgent?: string
+
   /** Last message count for stability detection */
   lastMsgCount?: number
   /** Number of consecutive polls with stable message count */