Disable inbox nesting on mobile

ui/src/lib/inbox.test.ts

@@ -24,6 +24,7 @@ import {
   loadLastInboxTab,
   normalizeInboxIssueColumns,
   RECENT_ISSUES_LIMIT,
+  resolveInboxNestingEnabled,
   resolveIssueWorkspaceName,
   resolveInboxSelectionIndex,
   saveInboxIssueColumns,
@@ -520,6 +521,19 @@ describe("inbox helpers", () => {
     expect(loadLastInboxTab()).toBe("all");
   });
 
+  it("keeps nesting enabled on desktop when the saved preference is on", () => {
+    expect(resolveInboxNestingEnabled(true, false)).toBe(true);
+  });
+
+  it("forces nesting off on mobile even when the saved preference is on", () => {
+    expect(resolveInboxNestingEnabled(true, true)).toBe(false);
+  });
+
+  it("keeps nesting off when the saved preference is off", () => {
+    expect(resolveInboxNestingEnabled(false, false)).toBe(false);
+    expect(resolveInboxNestingEnabled(false, true)).toBe(false);
+  });
+
   it("defaults issue columns to the current inbox layout", () => {
     expect(loadInboxIssueColumns()).toEqual(DEFAULT_INBOX_ISSUE_COLUMNS);
   });

ui/src/lib/inbox.ts

@@ -169,6 +169,10 @@ export function saveInboxNesting(enabled: boolean) {
   }
 }
 
+export function resolveInboxNestingEnabled(preferenceEnabled: boolean, isMobile: boolean): boolean {
+  return preferenceEnabled && !isMobile;
+}
+
 export function loadLastInboxTab(): InboxTab {
   try {
     const raw = localStorage.getItem(INBOX_LAST_TAB_KEY);