perf(renderer): skip unchanged kanban task cards

src/renderer/components/team/kanban/KanbanTaskCard.test.tsx

@@ -10,6 +10,7 @@ const unreadBadgeMock = vi.hoisted(() => ({
 
 const unreadCommentCountMock = vi.hoisted(() => ({
   value: 0,
+  calls: 0,
 }));
 
 vi.mock('@renderer/components/team/MemberBadge', () => ({
@@ -71,7 +72,10 @@ vi.mock('@renderer/hooks/useTheme', () => ({
 }));
 
 vi.mock('@renderer/hooks/useUnreadCommentCount', () => ({
-  useUnreadCommentCount: () => unreadCommentCountMock.value,
+  useUnreadCommentCount: () => {
+    unreadCommentCountMock.calls += 1;
+    return unreadCommentCountMock.value;
+  },
 }));
 
 /* eslint-enable @typescript-eslint/naming-convention -- Re-enable after component mocks. */
@@ -188,6 +192,7 @@ async function rerenderStrictTaskCard(
 afterEach(() => {
   unreadBadgeMock.props.length = 0;
   unreadCommentCountMock.value = 0;
+  unreadCommentCountMock.calls = 0;
 });
 
 async function renderTaskCard(
@@ -211,6 +216,56 @@ describe('KanbanTaskCard comment badge pulse', () => {
     document.body.innerHTML = '';
   });
 
+  it('skips rerender when refreshed task objects keep the same snapshot', async () => {
+    const taskMap = new Map();
+    const memberColorMap = new Map([['alice', 'blue']]);
+    const { root } = await renderTaskCard({
+      task: { ...baseTask, comments: [] },
+      taskMap,
+      memberColorMap,
+    });
+
+    expect(unreadCommentCountMock.calls).toBeGreaterThan(0);
+    unreadCommentCountMock.calls = 0;
+
+    await rerenderTaskCard(root, {
+      task: { ...baseTask, comments: [] },
+      taskMap,
+      memberColorMap,
+    });
+
+    expect(unreadCommentCountMock.calls).toBe(0);
+
+    await act(async () => {
+      root.unmount();
+      await flushReact();
+    });
+  });
+
+  it('rerenders when a hidden task field changes so click handlers stay current', async () => {
+    const taskMap = new Map();
+    const memberColorMap = new Map([['alice', 'blue']]);
+    const { root } = await renderTaskCard({
+      task: { ...baseTask, comments: [] },
+      taskMap,
+      memberColorMap,
+    });
+
+    unreadCommentCountMock.calls = 0;
+    await rerenderTaskCard(root, {
+      task: { ...baseTask, comments: [], description: 'Updated hidden details' },
+      taskMap,
+      memberColorMap,
+    });
+
+    expect(unreadCommentCountMock.calls).toBeGreaterThan(0);
+
+    await act(async () => {
+      root.unmount();
+      await flushReact();
+    });
+  });
+
   it('does not pulse on initial render with existing comments', async () => {
     const { host, root } = await renderTaskCard({
       task: { ...baseTask, comments: [createComment('comment-1')] },

src/renderer/components/team/kanban/KanbanTaskCard.tsx

@@ -83,6 +83,30 @@ interface CommentPulseSyncAction {
 }
 
 const EMPTY_TASK_COMMENTS: readonly TaskComment[] = [];
+const taskCardSignatureCache = new WeakMap<TeamTaskWithKanban, string>();
+
+function getTaskCardSignature(task: TeamTaskWithKanban): string {
+  const cached = taskCardSignatureCache.get(task);
+  if (cached !== undefined) return cached;
+
+  const signature = JSON.stringify(task);
+  taskCardSignatureCache.set(task, signature);
+  return signature;
+}
+
+function areKanbanTaskStatesEqual(
+  prev: KanbanTaskState | undefined,
+  next: KanbanTaskState | undefined
+): boolean {
+  if (prev === next) return true;
+  if (!prev || !next) return !prev && !next;
+  return (
+    prev.column === next.column &&
+    prev.reviewer === next.reviewer &&
+    prev.errorDescription === next.errorDescription &&
+    prev.movedAt === next.movedAt
+  );
+}
 
 function createCommentPulseState(
   taskKey: string,
@@ -652,10 +676,10 @@ export const KanbanTaskCard = memo(
     );
   },
   (prev, next) =>
-    prev.task === next.task &&
+    getTaskCardSignature(prev.task) === getTaskCardSignature(next.task) &&
     prev.teamName === next.teamName &&
     prev.columnId === next.columnId &&
-    prev.kanbanTaskState === next.kanbanTaskState &&
+    areKanbanTaskStatesEqual(prev.kanbanTaskState, next.kanbanTaskState) &&
     prev.hasReviewers === next.hasReviewers &&
     prev.compact === next.compact &&
     prev.taskMap === next.taskMap &&