diff --git a/apps/frontend/src/shared/types/investigation.ts b/apps/frontend/src/shared/types/investigation.ts
index 1d0c4851..c7c20d93 100644
--- a/apps/frontend/src/shared/types/investigation.ts
+++ b/apps/frontend/src/shared/types/investigation.ts
@@ -236,6 +236,8 @@ export interface InvestigationSettings {
   labelConsentGiven?: boolean;
   /** Custom investigation label configuration */
   labelCustomization?: InvestigationLabelCustomization;
+  /** Enable Opus 4.6 Fast Mode for investigations (2.5x faster, higher cost) */
+  fastInvestigations?: boolean;
 }
 
 // ============================================