Local data includes metadata (timestamp, source)

Stored records without timestamps or source markers make it impossible for the app to determine whether cached data is fresh, which copy won a conflict, or whether a local edit has been synced. ISO 25010:2011 reliability.recoverability requires that the system can determine the state of data after a failure — impossible without creation and modification timestamps. Without a source marker, merge logic cannot distinguish local-only edits from server-authoritative records. This undermines every higher-order pattern in this bundle: cache invalidation, conflict resolution, and sync-on-reconnect all require metadata to make correct decisions.

Add createdAt, updatedAt, source, and version fields to every data model written to local storage. Populate them at the point of save, not at the point of display.

interface StoredRecord {
  id: string;
  // ... domain fields ...
  createdAt: number;          // Unix ms
  updatedAt: number;          // Unix ms
  source: 'local' | 'remote'; // origin of last write
  version: number;            // schema version for migrations
}

export async function saveRecord(
  record: Omit<StoredRecord, 'createdAt' | 'updatedAt' | 'source' | 'version'>
) {
  const now = Date.now();
  const stored: StoredRecord = { ...record, createdAt: now, updatedAt: now, source: 'local', version: 1 };
  await AsyncStorage.setItem(`record_${record.id}`, JSON.stringify(stored));
}

export async function updateRecord(id: string, patch: Partial<StoredRecord>) {
  const existing = await loadRecord(id);
  if (!existing) return;
  await AsyncStorage.setItem(
    `record_${id}`,
    JSON.stringify({ ...existing, ...patch, updatedAt: Date.now() })
  );
}

Review all existing AsyncStorage.setItem call sites and add the four metadata fields to any schema that stores mutable domain data.