Update

backend/groups/index.js

@@ -16,6 +16,34 @@ const selectGroupsWithMembers = db.prepare(`
   ORDER BY g.name COLLATE NOCASE
 `);
 
+const selectGroupWithMembersById = db.prepare(`
+  SELECT
+    g.id,
+    g.name,
+    g.description,
+    g.created_at,
+    g.updated_at,
+    COUNT(DISTINCT u.id) AS member_count,
+    GROUP_CONCAT(u.id || '::' || u.username, '|||') AS member_pairs
+  FROM user_groups g
+  LEFT JOIN user_group_memberships m ON m.group_id = g.id
+  LEFT JOIN users u ON u.id = m.user_id
+  WHERE g.id = ?
+  GROUP BY g.id
+`);
+
+const selectGroupIdByName = db.prepare(`
+  SELECT id
+  FROM user_groups
+  WHERE lower(name) = lower(?)
+  LIMIT 1
+`);
+
+const insertGroupStatement = db.prepare(`
+  INSERT INTO user_groups (name, description, created_at, updated_at)
+  VALUES (?, ?, CURRENT_TIMESTAMP, CURRENT_TIMESTAMP)
+`);
+
 const parseMembers = (rawPairs) => {
   if (!rawPairs) {
     return [];
@@ -48,3 +76,25 @@ export function listGroups() {
   const rows = selectGroupsWithMembers.all();
   return rows.map(sanitizeGroup);
 }
+
+export function createGroup({ name, description }) {
+  const normalizedName = typeof name === 'string' ? name.trim() : '';
+  if (!normalizedName) {
+    const error = new Error('GROUP_NAME_REQUIRED');
+    error.code = 'GROUP_NAME_REQUIRED';
+    throw error;
+  }
+
+  const existing = selectGroupIdByName.get(normalizedName);
+  if (existing) {
+    const error = new Error('GROUP_NAME_TAKEN');
+    error.code = 'GROUP_NAME_TAKEN';
+    throw error;
+  }
+
+  const normalizedDescription = typeof description === 'string' ? description.trim() : null;
+  const insertResult = insertGroupStatement.run(normalizedName, normalizedDescription || null);
+  const groupId = Number(insertResult.lastInsertRowid);
+  const row = selectGroupWithMembersById.get(groupId);
+  return row ? sanitizeGroup(row) : null;
+}