fix: validate all snowball order rows upfront, reject invalid ones with 400

PATCH /api/snowball/order silently skipped rows with bad ids or invalid
snowball_order values via bare 'continue' — no feedback, partial updates.
Now validates every item before touching the DB, returning 400 on the first
bad entry. Also adds deleted_at IS NULL filter so soft-deleted bills are
skipped instead of updated silently.

routes/snowball.js

@@ -214,22 +214,44 @@ router.patch('/order', (req, res) => {
   if (!Array.isArray(items)) {
     return res.status(400).json(standardizeError('Request body must be an array', 'VALIDATION_ERROR'));
   }
+  if (items.length === 0) {
+    return res.json({ success: true, updated: 0 });
+  }
+
+  // Validate every row before touching the DB — no silent skips
+  const parsed = [];
+  for (let i = 0; i < items.length; i++) {
+    const row   = items[i];
+    const id    = parseInt(row?.id, 10);
+    const order = parseInt(row?.snowball_order, 10);
+    if (!Number.isInteger(id) || id <= 0) {
+      return res.status(400).json(standardizeError(
+        `Item at index ${i} has an invalid id: ${JSON.stringify(row?.id)}`,
+        'VALIDATION_ERROR',
+      ));
+    }
+    if (!Number.isInteger(order) || order < 0) {
+      return res.status(400).json(standardizeError(
+        `Item at index ${i} has an invalid snowball_order: ${JSON.stringify(row?.snowball_order)}`,
+        'VALIDATION_ERROR',
+      ));
+    }
+    parsed.push({ id, order });
+  }
 
   const db     = getDb();
   const userId = req.user.id;
-  const update = db.prepare('UPDATE bills SET snowball_order = ? WHERE id = ? AND user_id = ?');
+  const update = db.prepare(
+    'UPDATE bills SET snowball_order = ? WHERE id = ? AND user_id = ? AND deleted_at IS NULL'
+  );
 
-  db.transaction((rows) => {
-    for (const row of rows) {
-      const id    = parseInt(row.id, 10);
-      const order = parseInt(row.snowball_order, 10);
-      if (!Number.isInteger(id) || id <= 0) continue;
-      if (!Number.isInteger(order) || order < 0) continue;
+  db.transaction(() => {
+    for (const { id, order } of parsed) {
       update.run(order, id, userId);
     }
-  })(items);
+  })();
 
-  res.json({ success: true });
+  res.json({ success: true, updated: parsed.length });
 });
 
 // ── Snowball Plan helpers ─────────────────────────────────────────────────────