Refactor username handling in API and v2 routes for improved normalization

api.js

@@ -270,7 +270,7 @@ app.get('/generate', async (req, res) => {
 
         const config = {
             displayName: req.query.displayName || "Anonymous",
-            username: req.query.username || "@anonymous",
+            username: normalizeUsername(req.query.username),
             avatarUrl: fixDataUri(req.query.avatarUrl) || null,
             text: req.query.text || "No text provided",
             imageUrl: fixDataUri(req.query.imageUrl) || null,
@@ -336,12 +336,22 @@ function fixDataUri(dataUri) {
     }
 }
 
+function normalizeUsername(username) {
+    if (!username) return '@anonymous';
+
+    const trimmed = username.trim();
+
+    // If empty or just "@", return default
+    if (!trimmed || trimmed === '@') return '@anonymous';
+
+    // Add @ if it doesn't start with it
+    return trimmed.startsWith('@') ? trimmed : `@${trimmed}`;
+}
+
 app.post('/generate', async (req, res) => {
     try {
         const timestamp = req.body.timestamp ? formatTimestamp(parseInt(req.body.timestamp)) : formatTimestamp(Date.now() / 1000);
 
-        const username = req.body.username?.trim();
-
         // Only include engagement if all fields are provded
         let engagement = null;
         if (req.body.engagement &&
@@ -359,7 +369,7 @@ app.post('/generate', async (req, res) => {
 
         const config = {
             displayName: req.body.displayName || "Anonymous",
-            username: (username && username !== "@") ? username : "@anonymous",
+            username: normalizeUsername(req.body.username),
             avatarUrl: fixDataUri(req.body.avatarUrl) || null,
             text: req.body.text || "No text provided",
             imageUrl: fixDataUri(req.body.imageUrl) || null,