fix(core): require desktop inbox tab counts

Generated-By: PostHog Code
Task-Id: c1bbe3cf-742b-4b24-bf96-d11a18b4cf22

Author: richardsolomou

packages/core/src/inbox/engagement.ts

@@ -199,19 +199,27 @@ export type InboxViewedFilterState =
   | DesktopInboxViewedFilterState
   | MobileInboxViewedFilterState;
 
-export interface BuildInboxViewedInput {
+interface BuildInboxViewedInputBase {
   /**
    * Reports currently visible to the user (after reviewer scope + search), used
    * for `report_count`, `ready_count`, and the priority/actionability breakdown.
    */
   visibleReports: SignalReport[];
   /** Server-reported total of reports matching the active query — the headline inbox number. */
   totalCount: number;
-  /** Tab badge counts shown in the v2 header (the numbers the user actually sees). */
-  tabCounts?: { pulls: number; reports: number };
-  filters: InboxViewedFilterState;
 }
 
+export type BuildInboxViewedInput =
+  | (BuildInboxViewedInputBase & {
+      filters: DesktopInboxViewedFilterState;
+      /** Tab badge counts shown in the desktop header. */
+      tabCounts: { pulls: number; reports: number };
+    })
+  | (BuildInboxViewedInputBase & {
+      filters: MobileInboxViewedFilterState;
+      tabCounts?: never;
+    });
+
 /**
  * Build the property payload for the `Inbox viewed` analytics event from the
  * v2 inbox state. Pure so it can be unit-tested and reused across hosts.