diff --git a/configurator/src/App.svelte b/configurator/src/App.svelte
index 5cd8b467..49aca477 100644
--- a/configurator/src/App.svelte
+++ b/configurator/src/App.svelte
@@ -48,10 +48,17 @@
   let canUndo = $derived(past.length > 0);
   let canRedo = $derived(future.length > 0);
 
+  // Shallow equality for flat string records — much cheaper than JSON.stringify on every tick.
+  function shallowEq(a: Record<string, string>, b: Record<string, string>): boolean {
+    const ak = Object.keys(a);
+    if (ak.length !== Object.keys(b).length) return false;
+    return ak.every((k) => a[k] === b[k]);
+  }
+
   // Save state — hasPendingChanges is derived so undo/redo update it automatically.
-  let lastSavedSnapshot = $state(JSON.stringify(overrides));
+  let lastSavedOverrides = $state<Record<string, string>>({ ...overrides });
   let saveState = $state<'idle' | 'saving' | 'saved'>('idle');
-  let hasPendingChanges = $derived(JSON.stringify(overrides) !== lastSavedSnapshot);
+  let hasPendingChanges = $derived(!shallowEq(overrides, lastSavedOverrides));
   let saveStateTimer: ReturnType<typeof setTimeout> | null = null;
 
   // Live CSS preview on every change — actual persistence only on explicit save.
@@ -60,7 +67,7 @@
   function setOverrides(updater: ((prev: Record<string, string>) => Record<string, string>) | Record<string, string>) {
     const prev = overrides;
     const next = typeof updater === "function" ? updater(prev) : updater;
-    if (JSON.stringify(prev) !== JSON.stringify(next)) {
+    if (!shallowEq(prev, next)) {
       past = [...past.slice(-49), prev];
       future = [];
       if (saveState === 'saved') saveState = 'idle';
@@ -70,13 +77,13 @@
 
   async function handleSave() {
     if (!hasPendingChanges || saveState === 'saving') return;
-    const snapshot = JSON.stringify(overrides);
+    const snapshot = { ...overrides };
     saveState = 'saving';
     try {
       await saveOverrides(overrides);
       // Only mark clean if overrides haven't changed since save started.
-      if (JSON.stringify(overrides) === snapshot) {
-        lastSavedSnapshot = snapshot;
+      if (shallowEq(overrides, snapshot)) {
+        lastSavedOverrides = snapshot;
         saveState = 'saved';
         if (saveStateTimer) clearTimeout(saveStateTimer);
         saveStateTimer = setTimeout(() => {
diff --git a/configurator/src/components/shell/StudioHeader.svelte b/configurator/src/components/shell/StudioHeader.svelte
index 66eb22d7..3004fb3c 100644
--- a/configurator/src/components/shell/StudioHeader.svelte
+++ b/configurator/src/components/shell/StudioHeader.svelte
@@ -1,4 +1,5 @@
 <script lang="ts">
+  import { tick } from 'svelte';
   import { Undo2, Redo2, Trash2, Share2, FolderOpen, Check, Save, Loader2 } from 'lucide-svelte';
 
   const version = typeof __SLASHED_VERSION__ !== "undefined" ? __SLASHED_VERSION__ : "";
@@ -18,6 +19,15 @@
   } = $props();
 
   let shareFeedback = $state(false);
+  let showResetConfirm = $state(false);
+  let resetCancelBtn = $state<HTMLButtonElement | null>(null);
+  let resetConfirmBtn = $state<HTMLButtonElement | null>(null);
+
+  $effect(() => {
+    if (showResetConfirm) {
+      tick().then(() => resetCancelBtn?.focus());
+    }
+  });
 
   async function handleShare() {
     try {
@@ -28,6 +38,19 @@
       // ignore
     }
   }
+
+  function handleResetAllClick() {
+    showResetConfirm = true;
+  }
+
+  function confirmReset() {
+    showResetConfirm = false;
+    onResetAll();
+  }
+
+  function cancelReset() {
+    showResetConfirm = false;
+  }
 </script>
 
 <header class="h-[52px] bg-[#0d0d14] border-b border-white/8 flex items-center px-3 gap-3 shrink-0 z-20">
@@ -60,6 +83,31 @@
   <div class="flex-1"></div>
 
   <div class="flex items-center gap-1.5">
+    <button
+      onclick={onSave}
+      disabled={!hasPendingChanges || saveState === 'saving'}
+      title={hasPendingChanges ? "Save changes (Ctrl+S)" : "No unsaved changes"}
+      class={[
+        "flex items-center gap-1.5 px-3 py-1.5 rounded-lg text-[11px] font-bold transition-colors cursor-pointer",
+        saveState === 'saved'
+          ? "bg-emerald-900/40 border border-emerald-500/30 text-emerald-300"
+          : hasPendingChanges
+            ? "bg-emerald-600 hover:bg-emerald-500 text-white shadow-sm shadow-emerald-600/30"
+            : "bg-white/5 text-slate-500 disabled:opacity-40 disabled:pointer-events-none",
+      ].join(' ')}
+    >
+      {#if saveState === 'saving'}
+        <Loader2 class="w-3.5 h-3.5 animate-spin" />
+        Saving…
+      {:else if saveState === 'saved'}
+        <Check class="w-3.5 h-3.5" />
+        Saved
+      {:else}
+        <Save class="w-3.5 h-3.5" />
+        Save
+      {/if}
+    </button>
+
     <button
       onclick={onUndo}
       disabled={!canUndo}
@@ -100,39 +148,55 @@
     </button>
 
     <button
-      onclick={onResetAll}
+      onclick={handleResetAllClick}
       disabled={overridesCount === 0}
       title="Reset all overrides"
       class="p-1.5 rounded-lg text-rose-400 hover:text-rose-300 hover:bg-rose-500/10 disabled:opacity-25 disabled:pointer-events-none transition-all cursor-pointer"
     >
       <Trash2 class="w-3.5 h-3.5" />
     </button>
-
-    <div class="w-px h-4 bg-white/10 mx-1"></div>
-
-    <button
-      onclick={onSave}
-      disabled={!hasPendingChanges || saveState === 'saving'}
-      title={hasPendingChanges ? "Save changes (Ctrl+S)" : "No unsaved changes"}
-      class={[
-        "flex items-center gap-1.5 px-3 py-1.5 rounded-lg text-[11px] font-bold transition-all cursor-pointer",
-        saveState === 'saved'
-          ? "bg-emerald-900/40 border border-emerald-500/30 text-emerald-300"
-          : hasPendingChanges
-            ? "bg-emerald-600 hover:bg-emerald-500 text-white shadow-sm shadow-emerald-600/30"
-            : "bg-white/5 text-slate-500 disabled:opacity-40 disabled:pointer-events-none",
-      ].join(' ')}
-    >
-      {#if saveState === 'saving'}
-        <Loader2 class="w-3.5 h-3.5 animate-spin" />
-        Saving…
-      {:else if saveState === 'saved'}
-        <Check class="w-3.5 h-3.5" />
-        Saved
-      {:else}
-        <Save class="w-3.5 h-3.5" />
-        Save
-      {/if}
-    </button>
   </div>
 </header>
+
+{#if showResetConfirm}
+  <div
+    class="fixed inset-0 z-50 flex items-center justify-center bg-black/60 backdrop-blur-sm"
+    role="dialog"
+    aria-modal="true"
+    aria-labelledby="reset-confirm-title"
+    onclick={(e) => { if (e.target === e.currentTarget) cancelReset(); }}
+    onkeydown={(e) => {
+      if (e.key === 'Escape') { e.stopPropagation(); cancelReset(); }
+      if (e.key === 'Tab') {
+        e.preventDefault();
+        const focused = document.activeElement;
+        if (focused === resetCancelBtn) resetConfirmBtn?.focus();
+        else resetCancelBtn?.focus();
+      }
+    }}
+  >
+    <div class="bg-[#1a1a2e] border border-white/10 rounded-xl p-6 max-w-sm w-full mx-4 shadow-2xl">
+      <h3 id="reset-confirm-title" class="text-white font-bold text-sm mb-2">Reset all overrides?</h3>
+      <p class="text-slate-400 text-xs mb-5">
+        This will clear all {overridesCount} customisation{overridesCount !== 1 ? 's' : ''}.
+        You can still undo this before saving.
+      </p>
+      <div class="flex gap-2 justify-end">
+        <button
+          bind:this={resetCancelBtn}
+          onclick={cancelReset}
+          class="px-3 py-1.5 text-xs rounded-lg bg-white/8 text-slate-300 hover:bg-white/12 transition-colors cursor-pointer"
+        >
+          Cancel
+        </button>
+        <button
+          bind:this={resetConfirmBtn}
+          onclick={confirmReset}
+          class="px-3 py-1.5 text-xs rounded-lg bg-rose-600 hover:bg-rose-500 text-white font-bold transition-colors cursor-pointer"
+        >
+          Reset all
+        </button>
+      </div>
+    </div>
+  </div>
+{/if}