diff --git a/_headers b/_headers
index e9c45ca..ca7e0c7 100644
--- a/_headers
+++ b/_headers
@@ -1,3 +1,14 @@
+/*
+  Content-Security-Policy: default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline' https://fonts.googleapis.com; font-src 'self' https://fonts.gstatic.com; img-src 'self' data:; connect-src 'self'; manifest-src 'self'; worker-src 'self'; frame-ancestors 'none'; base-uri 'self'; form-action 'self'; object-src 'none'; upgrade-insecure-requests
+  X-Frame-Options: DENY
+  X-Content-Type-Options: nosniff
+  Referrer-Policy: no-referrer
+  Permissions-Policy: accelerometer=(), camera=(), geolocation=(), gyroscope=(), magnetometer=(), microphone=(), payment=(), usb=(), interest-cohort=()
+  Strict-Transport-Security: max-age=31536000; includeSubDomains; preload
+  Cross-Origin-Opener-Policy: same-origin
+  Cross-Origin-Resource-Policy: same-origin
+  Cross-Origin-Embedder-Policy: credentialless
+
 /sw.js
   Cache-Control: no-cache, no-store, must-revalidate
   Service-Worker-Allowed: /
diff --git a/app.js b/app.js
index 602fcfa..b296e45 100644
--- a/app.js
+++ b/app.js
@@ -559,29 +559,57 @@ document.addEventListener('DOMContentLoaded', () => {
   window.addEventListener('pagehide', saveProgress);
   window.addEventListener('beforeunload', saveProgress);
 
+  const ALLOWED_SPECIES = ['green', 'loggerhead', 'leatherback'];
+  function clampStat(n) {
+    const v = Number(n);
+    if (!Number.isFinite(v)) return 0;
+    return Math.max(0, Math.min(100, v));
+  }
+  function sanitizeName(n) {
+    if (typeof n !== 'string') return 'Shelly';
+    // Strip control chars and HTML-relevant punctuation; cap at 12 like the input.
+    const cleaned = n.replace(/[ -<>"'`\\]/g, '').trim().slice(0, 12);
+    return cleaned.length ? cleaned : 'Shelly';
+  }
+
   function loadProgress() {
     const saved = localStorage.getItem('tortugotchi_save');
     if (!saved) return false;
-    try {
-      const data = JSON.parse(saved);
-      turtleName = data.name || 'Shelly';
-      turtleSpecies = data.species || 'green';
-      turtleAge = data.age || 0;
-      stats = data.stats || { health: 100, hunger: 80, joy: 80, clean: 100 };
-      isSick = data.isSick || false;
-
-      // Offline progression: apply the time the player was away.
-      // Capped at 24h of decay so a multi-week absence doesn't kill the turtle.
-      if (data.savedAt) {
-        const elapsedSec = Math.max(0, (Date.now() - data.savedAt) / 1000);
-        const cappedSec = Math.min(elapsedSec, 24 * 60 * 60);
-        applyOfflineProgression(cappedSec);
-      }
-      return true;
-    } catch (e) {
-      console.error("Failed to load save file, resetting.", e);
+    // Reject obviously oversized payloads (defends against extension-planted bloat).
+    if (saved.length > 4096) {
+      console.warn('Save file rejected: oversized.');
+      localStorage.removeItem('tortugotchi_save');
       return false;
     }
+    let data;
+    try { data = JSON.parse(saved); } catch (e) {
+      console.error('Failed to parse save file, resetting.', e);
+      return false;
+    }
+    if (!data || typeof data !== 'object' || Array.isArray(data)) return false;
+
+    turtleName = sanitizeName(data.name);
+    turtleSpecies = ALLOWED_SPECIES.includes(data.species) ? data.species : 'green';
+    const ageNum = Number(data.age);
+    turtleAge = Number.isFinite(ageNum) && ageNum >= 0 ? Math.floor(ageNum) : 0;
+
+    const s = data.stats && typeof data.stats === 'object' && !Array.isArray(data.stats)
+      ? data.stats : {};
+    stats = {
+      health: clampStat(s.health ?? 100),
+      hunger: clampStat(s.hunger ?? 80),
+      joy:    clampStat(s.joy    ?? 80),
+      clean:  clampStat(s.clean  ?? 100)
+    };
+    isSick = data.isSick === true;
+
+    const savedAt = Number(data.savedAt);
+    if (Number.isFinite(savedAt) && savedAt > 0 && savedAt <= Date.now()) {
+      const elapsedSec = Math.max(0, (Date.now() - savedAt) / 1000);
+      const cappedSec = Math.min(elapsedSec, 24 * 60 * 60);
+      applyOfflineProgression(cappedSec);
+    }
+    return true;
   }
 
   function applyOfflineProgression(seconds) {
@@ -2307,12 +2335,8 @@ document.addEventListener('DOMContentLoaded', () => {
   });
 
   btnSaveRename.addEventListener('click', () => {
-    const inputName = document.getElementById('input-turtle-name').value.trim();
-    if (inputName.length > 0) {
-      turtleName = inputName;
-    } else {
-      turtleName = 'Shelly';
-    }
+    const raw = document.getElementById('input-turtle-name').value;
+    turtleName = sanitizeName(raw);
     
     modals.rename.classList.add('hidden');
     
diff --git a/sw.js b/sw.js
index 4f05b21..8f10c80 100644
--- a/sw.js
+++ b/sw.js
@@ -1,4 +1,4 @@
-const CACHE_NAME = 'tortugotchi-v10';
+const CACHE_NAME = 'tortugotchi-v11';
 const ASSETS = [
   './',
   './index.html',
@@ -9,43 +9,40 @@ const ASSETS = [
   './icon-512.png'
 ];
 
-// Install Event
 self.addEventListener('install', (e) => {
   e.waitUntil(
-    caches.open(CACHE_NAME).then((cache) => {
-      console.log('[Service Worker] Caching all app shell assets');
-      return cache.addAll(ASSETS);
-    }).then(() => self.skipWaiting())
+    caches.open(CACHE_NAME)
+      .then((cache) => cache.addAll(ASSETS))
+      .then(() => self.skipWaiting())
   );
 });
 
-// Activate Event
 self.addEventListener('activate', (e) => {
   e.waitUntil(
-    caches.keys().then((keys) => {
-      return Promise.all(
-        keys.map((key) => {
-          if (key !== CACHE_NAME) {
-            console.log('[Service Worker] Removing old cache', key);
-            return caches.delete(key);
-          }
-        })
-      );
-    }).then(() => self.clients.claim())
+    caches.keys()
+      .then((keys) => Promise.all(
+        keys.filter((k) => k !== CACHE_NAME).map((k) => caches.delete(k))
+      ))
+      .then(() => self.clients.claim())
   );
 });
 
-// Fetch Event
 self.addEventListener('fetch', (e) => {
+  const req = e.request;
+
+  // Only handle GETs over http(s) to our own origin. Skip POST/PUT/DELETE,
+  // chrome-extension://, data:, blob:, ws:, and cross-origin requests so the
+  // worker can never be coerced into serving the wrong response.
+  if (req.method !== 'GET') return;
+  let url;
+  try { url = new URL(req.url); } catch { return; }
+  if (url.protocol !== 'https:' && url.protocol !== 'http:') return;
+  if (url.origin !== self.location.origin) return;
+
   e.respondWith(
-    caches.match(e.request).then((cachedResponse) => {
-      // Return cached version or fetch from network
-      return cachedResponse || fetch(e.request).catch(() => {
-        // Fallback for document requests if completely offline
-        if (e.request.destination === 'document') {
-          return caches.match('./index.html');
-        }
-      });
-    })
+    caches.match(req).then((cached) => cached || fetch(req).catch(() => {
+      if (req.destination === 'document') return caches.match('./index.html');
+      return new Response('', { status: 504, statusText: 'Offline' });
+    }))
   );
 });