[Init] Initial commit - NetMesh terminal manager

domain/systemManager/pollListStable.ts

@@ -0,0 +1,50 @@
+function pollSnapshotEqual<T>(prev: T | null, next: T): boolean {
+  if (prev === next) return true;
+  if (prev === null) return false;
+  try {
+    return JSON.stringify(prev) === JSON.stringify(next);
+  } catch {
+    return false;
+  }
+}
+
+function itemSnapshotEqual<T>(a: T, b: T): boolean {
+  if (a === b) return true;
+  try {
+    return JSON.stringify(a) === JSON.stringify(b);
+  } catch {
+    return false;
+  }
+}
+
+/** Skip React state updates when polled payload is unchanged. */
+export function nextPollData<T>(prev: T | null, next: T): T {
+  return pollSnapshotEqual(prev, next) ? prev as T : next;
+}
+
+/**
+ * Merge polled list rows by key, reusing previous item references when unchanged.
+ * Keeps React.memo row components from re-rendering when other rows update.
+ */
+export function mergePollListByKey<T, K extends string | number>(
+  prev: T[] | null,
+  next: T[],
+  getKey: (item: T) => K,
+  isEqual: (a: T, b: T) => boolean = itemSnapshotEqual,
+): T[] {
+  if (prev === null) return next;
+  if (prev.length !== next.length) return next;
+
+  const nextByKey = new Map(next.map((item) => [getKey(item), item]));
+  if (prev.some((item) => !nextByKey.has(getKey(item)))) return next;
+  if (next.some((item) => !prev.some((p) => getKey(p) === getKey(item)))) return next;
+
+  let changed = false;
+  const merged = prev.map((oldItem) => {
+    const newItem = nextByKey.get(getKey(oldItem))!;
+    if (isEqual(oldItem, newItem)) return oldItem;
+    changed = true;
+    return newItem;
+  });
+  return changed ? merged : prev;
+}