feat: Auto-load saved user and remember last visited room

- JoinForm now pre-populates name/emoji from localStorage and shows
  a "Quick Join as [name]" button for returning users
- Home page shows "Rejoin /[room]" button when user has visited before
- Room slug saved to localStorage on every visit for quick rejoin

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/app/[slug]/page.tsx

@@ -46,6 +46,8 @@ export default function RoomPage() {
     const stored = localStorage.getItem('rmaps_user');
     if (stored) {
       setCurrentUser(JSON.parse(stored));
+      // Save this as the last visited room
+      localStorage.setItem('rmaps_last_room', slug);
       // Check if user had location sharing enabled for this room
       const sharingPref = localStorage.getItem(`rmaps_sharing_${slug}`);
       if (sharingPref === 'true') {
@@ -61,6 +63,7 @@ export default function RoomPage() {
   const handleJoin = (name: string, emoji: string) => {
     const user = { name, emoji };
     localStorage.setItem('rmaps_user', JSON.stringify(user));
+    localStorage.setItem('rmaps_last_room', slug);
     setCurrentUser(user);
     setNeedsJoin(false);
   };

src/app/page.tsx

@@ -20,6 +20,7 @@ export default function HomePage() {
   const [emoji, setEmoji] = useState('');
   const [roomName, setRoomName] = useState('');
   const [isLoaded, setIsLoaded] = useState(false);
+  const [lastRoom, setLastRoom] = useState<string | null>(null);
 
   // Load saved user info from localStorage on mount
   useEffect(() => {
@@ -34,6 +35,11 @@ export default function HomePage() {
           loadedEmoji = user.emoji;
         }
       }
+      // Load last visited room
+      const lastVisited = localStorage.getItem('rmaps_last_room');
+      if (lastVisited) {
+        setLastRoom(lastVisited);
+      }
     } catch {
       // Ignore parse errors
     }
@@ -53,6 +59,7 @@ export default function HomePage() {
 
     // Store user info in localStorage for the session
     localStorage.setItem('rmaps_user', JSON.stringify({ name, emoji }));
+    localStorage.setItem('rmaps_last_room', slug);
 
     // Navigate to the room (will create it if it doesn't exist)
     router.push(`/${slug}`);
@@ -65,9 +72,16 @@ export default function HomePage() {
 
     // Clean the slug
     const cleanSlug = joinSlug.toLowerCase().replace(/[^a-z0-9-]/g, '');
+    localStorage.setItem('rmaps_last_room', cleanSlug);
     router.push(`/${cleanSlug}`);
   };
 
+  const handleRejoinLastRoom = () => {
+    if (!name.trim() || !lastRoom) return;
+    localStorage.setItem('rmaps_user', JSON.stringify({ name, emoji }));
+    router.push(`/${lastRoom}`);
+  };
+
   return (
     <main className="min-h-screen flex flex-col items-center justify-center p-4">
       <div className="max-w-md w-full space-y-8">
@@ -79,6 +93,23 @@ export default function HomePage() {
           <p className="text-white/60">Find your friends at events</p>
         </div>
 
+        {/* Quick Rejoin Card - show when user has saved info and last room */}
+        {isLoaded && name && lastRoom && (
+          <div className="room-panel rounded-2xl p-6">
+            <p className="text-white/60 text-sm text-center mb-4">Welcome back, {name}!</p>
+            <button
+              onClick={handleRejoinLastRoom}
+              className="btn-primary w-full text-lg py-3 flex items-center justify-center gap-2"
+            >
+              <span className="text-xl">{emoji}</span>
+              <span>Rejoin /{lastRoom}</span>
+            </button>
+            <p className="text-white/40 text-xs text-center mt-3">
+              Or create/join a different room below
+            </p>
+          </div>
+        )}
+
         {/* Main Card */}
         <div className="room-panel rounded-2xl p-6 space-y-6">
           {/* User Setup */}

src/components/room/JoinForm.tsx

@@ -1,6 +1,6 @@
 'use client';
 
-import { useState } from 'react';
+import { useState, useEffect } from 'react';
 
 const EMOJIS = ['😀', '😎', '🤓', '🥳', '🦊', '🐱', '🐶', '🦄', '🌟', '🔥', '💜', '🎮'];
 
@@ -11,7 +11,31 @@ interface JoinFormProps {
 
 export default function JoinForm({ roomSlug, onJoin }: JoinFormProps) {
   const [name, setName] = useState('');
-  const [emoji, setEmoji] = useState(EMOJIS[Math.floor(Math.random() * EMOJIS.length)]);
+  const [emoji, setEmoji] = useState('');
+  const [isLoaded, setIsLoaded] = useState(false);
+
+  // Load saved user info from localStorage
+  useEffect(() => {
+    let loadedEmoji = '';
+    try {
+      const stored = localStorage.getItem('rmaps_user');
+      if (stored) {
+        const user = JSON.parse(stored);
+        if (user.name) setName(user.name);
+        if (user.emoji) {
+          setEmoji(user.emoji);
+          loadedEmoji = user.emoji;
+        }
+      }
+    } catch {
+      // Ignore parse errors
+    }
+    // Set random emoji if none loaded
+    if (!loadedEmoji) {
+      setEmoji(EMOJIS[Math.floor(Math.random() * EMOJIS.length)]);
+    }
+    setIsLoaded(true);
+  }, []);
 
   const handleSubmit = (e: React.FormEvent) => {
     e.preventDefault();
@@ -30,6 +54,24 @@ export default function JoinForm({ roomSlug, onJoin }: JoinFormProps) {
           </p>
         </div>
 
+        {/* Quick join option if user already has saved info */}
+        {isLoaded && name && (
+          <div className="mb-6 p-4 bg-rmaps-primary/10 border border-rmaps-primary/30 rounded-lg">
+            <p className="text-white/60 text-sm mb-3 text-center">Welcome back!</p>
+            <button
+              type="button"
+              onClick={() => onJoin(name.trim(), emoji)}
+              className="w-full btn-primary py-3 flex items-center justify-center gap-2"
+            >
+              <span className="text-xl">{emoji}</span>
+              <span>Join as {name}</span>
+            </button>
+            <p className="text-white/40 text-xs text-center mt-2">
+              Or customize below
+            </p>
+          </div>
+        )}
+
         <form onSubmit={handleSubmit} className="space-y-4">
           {/* Emoji picker */}
           <div>