diff --git a/src/components/AppMenu.vue b/src/components/AppMenu.vue
index 736c816dc..5e8db6aaf 100644
--- a/src/components/AppMenu.vue
+++ b/src/components/AppMenu.vue
@@ -174,10 +174,11 @@ const topMenus = [
 <template>
   <div class="shrink-0 border-b border-border">
     <div class="flex items-center gap-2 px-2 py-1.5">
-      <img src="/favicon-32.png" class="size-4" alt="OpenPencil" />
+      <img data-test-id="app-logo" src="/favicon-32.png" class="size-4" alt="OpenPencil" />
       <input
         v-if="editingName"
         data-doc-name-edit
+        data-test-id="app-document-name-input"
         class="min-w-0 flex-1 rounded border border-accent bg-input px-1 py-0.5 text-xs text-surface outline-none"
         :value="store.state.documentName"
         @blur="commitRename($event.target as HTMLInputElement)"
@@ -186,11 +187,13 @@ const topMenus = [
       />
       <span
         v-else
+        data-test-id="app-document-name"
         class="min-w-0 flex-1 cursor-default truncate rounded px-1 py-0.5 text-xs text-surface hover:bg-hover"
         @dblclick="startRename"
         >{{ store.state.documentName }}</span
       >
       <button
+        data-test-id="app-toggle-ui"
         class="flex size-6 shrink-0 cursor-pointer items-center justify-center rounded text-muted transition-colors hover:bg-hover hover:text-surface"
         title="Toggle UI (⌘\)"
         @click="store.state.showUI = !store.state.showUI"
@@ -202,6 +205,7 @@ const topMenus = [
       <MenubarRoot class="flex items-center gap-0.5 overflow-x-auto scrollbar-none">
         <MenubarMenu v-for="menu in topMenus" :key="menu.label">
           <MenubarTrigger
+            :data-test-id="`menubar-${menu.label.toLowerCase()}`"
             class="flex cursor-pointer items-center rounded px-2 py-1 text-xs text-muted transition-colors select-none hover:bg-hover hover:text-surface data-[state=open]:bg-hover data-[state=open]:text-surface"
           >
             {{ menu.label }}
diff --git a/src/components/AppSelect.vue b/src/components/AppSelect.vue
index 06418a6de..b0fa64ba8 100644
--- a/src/components/AppSelect.vue
+++ b/src/components/AppSelect.vue
@@ -22,6 +22,7 @@ const modelValue = defineModel<T>({ required: true })
 <template>
   <SelectRoot v-model="modelValue">
     <SelectTrigger
+      data-test-id="app-select-trigger"
       class="flex min-w-0 flex-1 cursor-pointer items-center justify-between rounded border border-border bg-input px-1.5 py-1 text-xs text-surface outline-none hover:bg-hover"
     >
       <SelectValue :placeholder="placeholder" />
diff --git a/src/components/AppToast.vue b/src/components/AppToast.vue
index 87275f69e..5b1f15b40 100644
--- a/src/components/AppToast.vue
+++ b/src/components/AppToast.vue
@@ -13,6 +13,7 @@ const { copy, copied } = useClipboard({ copiedDuring: 1500 })
     <ToastRoot
       v-for="t in toast.toasts.value"
       :key="t.id"
+      data-test-id="toast-item"
       :duration="t.variant === 'error' ? 0 : toast.TOAST_DURATION"
       class="flex max-w-sm items-start gap-1.5 rounded-md px-2.5 py-1.5 text-xs text-white shadow-md data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=open]:fade-in data-[state=open]:slide-in-from-top-1 data-[state=closed]:fade-out data-[state=closed]:slide-out-to-top-1 data-[swipe=move]:translate-y-[var(--reka-toast-swipe-move-y)] data-[swipe=cancel]:translate-y-0 data-[swipe=cancel]:transition-transform"
       :class="t.variant === 'error' ? 'bg-red-600' : 'bg-blue-600'"
@@ -27,6 +28,7 @@ const { copy, copied } = useClipboard({ copiedDuring: 1500 })
       <ToastDescription class="min-w-0 flex-1 select-text">{{ t.message }}</ToastDescription>
       <button
         v-if="t.variant === 'error'"
+        data-test-id="toast-copy-error"
         class="mt-0.5 shrink-0 cursor-pointer rounded p-0.5 opacity-70 hover:opacity-100"
         :title="copied ? 'Copied!' : 'Copy error'"
         @click="copy(t.message)"
@@ -36,6 +38,7 @@ const { copy, copied } = useClipboard({ copiedDuring: 1500 })
       </button>
       <ToastClose
         v-if="t.variant === 'error'"
+        data-test-id="toast-close"
         class="mt-0.5 shrink-0 cursor-pointer rounded p-0.5 opacity-70 hover:opacity-100"
       >
         <icon-lucide-x class="size-3" />
diff --git a/src/components/ChatPanel.vue b/src/components/ChatPanel.vue
index adfd2f0b7..0e1ae0afa 100644
--- a/src/components/ChatPanel.vue
+++ b/src/components/ChatPanel.vue
@@ -40,7 +40,7 @@ function handleStop() {
 </script>
 
 <template>
-  <div class="flex min-w-0 flex-1 flex-col overflow-hidden">
+  <div data-test-id="chat-panel" class="flex min-w-0 flex-1 flex-col overflow-hidden">
     <APIKeySetup v-if="!isConfigured" />
 
     <template v-else>
@@ -49,6 +49,7 @@ function handleStop() {
           <!-- Empty state -->
           <div
             v-if="messages.length === 0"
+            data-test-id="chat-empty-state"
             class="flex h-full flex-col items-center justify-center gap-3 text-muted"
           >
             <icon-lucide-message-circle class="size-8 opacity-50" />
@@ -56,11 +57,15 @@ function handleStop() {
           </div>
 
           <!-- Messages -->
-          <div v-else class="flex flex-col gap-3">
+          <div v-else data-test-id="chat-messages" class="flex flex-col gap-3">
             <ChatMessage v-for="msg in messages" :key="msg.id" :message="msg" />
 
             <!-- Typing indicator -->
-            <div v-if="status === 'submitted'" class="flex gap-2">
+            <div
+              v-if="status === 'submitted'"
+              data-test-id="chat-typing-indicator"
+              class="flex gap-2"
+            >
               <div
                 class="flex size-6 shrink-0 items-center justify-center rounded-full bg-muted/20 text-[10px] font-bold text-muted"
               >
diff --git a/src/components/CodePanel.vue b/src/components/CodePanel.vue
index e82ce0e49..931f5cee3 100644
--- a/src/components/CodePanel.vue
+++ b/src/components/CodePanel.vue
@@ -38,14 +38,22 @@ watch(jsxCode, () => {
 </script>
 
 <template>
-  <div v-if="!jsxCode" class="flex flex-1 items-center justify-center px-4 text-center">
+  <div
+    v-if="!jsxCode"
+    data-test-id="code-panel-empty"
+    class="flex flex-1 items-center justify-center px-4 text-center"
+  >
     <span class="text-xs text-muted">Select a layer to see its JSX code</span>
   </div>
 
-  <div v-else class="flex min-h-0 flex-1 flex-col">
-    <div class="flex shrink-0 items-center justify-between border-b border-border px-3 py-1.5">
+  <div v-else data-test-id="code-panel" class="flex min-h-0 flex-1 flex-col">
+    <div
+      data-test-id="code-panel-header"
+      class="flex shrink-0 items-center justify-between border-b border-border px-3 py-1.5"
+    >
       <span class="text-[11px] text-muted">JSX</span>
       <button
+        data-test-id="code-panel-copy"
         class="flex items-center gap-1 rounded px-1.5 py-0.5 text-[11px] text-muted hover:bg-hover hover:text-surface"
         @click="copyCode"
       >
diff --git a/src/components/CollabPanel.vue b/src/components/CollabPanel.vue
index 3ede64471..68705b05a 100644
--- a/src/components/CollabPanel.vue
+++ b/src/components/CollabPanel.vue
@@ -92,6 +92,7 @@ function initials(name: string): string {
         <TooltipRoot>
           <TooltipTrigger as-child>
             <div
+              data-test-id="collab-local-avatar"
               class="flex size-6 items-center justify-center rounded-full border-2 border-panel text-[10px] font-semibold text-white"
               :style="{ background: colorToCSS(state.localColor) }"
             >
@@ -111,6 +112,7 @@ function initials(name: string): string {
         <TooltipRoot v-for="peer in peers" :key="peer.clientId">
           <TooltipTrigger as-child>
             <div
+              data-test-id="collab-peer-avatar"
               class="flex size-6 cursor-pointer items-center justify-center rounded-full border-2 text-[10px] font-semibold text-white transition-all"
               :class="
                 followingPeer === peer.clientId
@@ -145,6 +147,7 @@ function initials(name: string): string {
     <PopoverRoot v-model:open="popoverOpen">
       <PopoverTrigger as-child>
         <button
+          data-test-id="collab-share-button"
           class="flex h-7 cursor-pointer items-center gap-1.5 rounded-md border-none px-3 text-xs font-medium transition-colors"
           :class="
             state.connected
@@ -161,6 +164,7 @@ function initials(name: string): string {
 
       <PopoverPortal>
         <PopoverContent
+          data-test-id="collab-popover"
           class="z-50 w-72 rounded-lg border border-border bg-panel p-3 shadow-xl"
           :side-offset="8"
           side="bottom"
@@ -173,10 +177,12 @@ function initials(name: string): string {
               <input
                 :value="shareUrl"
                 readonly
+                data-test-id="collab-room-link"
                 class="min-w-0 flex-1 rounded border border-border bg-input px-2 py-1 text-xs text-surface"
                 @focus="($event.target as HTMLInputElement).select()"
               />
               <button
+                data-test-id="collab-copy-link"
                 class="flex h-7 cursor-pointer items-center gap-1 rounded border-none bg-accent px-2 text-xs text-white hover:bg-accent/90"
                 @click="copyLink"
               >
@@ -191,6 +197,7 @@ function initials(name: string): string {
             </div>
 
             <button
+              data-test-id="collab-disconnect"
               class="flex h-7 w-full cursor-pointer items-center justify-center rounded border border-border bg-transparent text-xs text-muted hover:bg-hover hover:text-surface"
               @click="emit('disconnect')"
             >
@@ -209,6 +216,7 @@ function initials(name: string): string {
               <label class="mb-1 block text-xs text-muted">Your name</label>
               <input
                 v-model="nameDraft"
+                data-test-id="collab-name-input"
                 class="w-full rounded border border-border bg-input px-2 py-1 text-xs text-surface"
                 placeholder="Enter your name"
                 autofocus
@@ -217,6 +225,7 @@ function initials(name: string): string {
             </div>
 
             <button
+              data-test-id="collab-join-button"
               class="flex h-8 w-full cursor-pointer items-center justify-center gap-1.5 rounded border-none bg-accent text-xs font-medium text-white hover:bg-accent/90 disabled:opacity-50"
               :disabled="!nameDraft.trim()"
               @click="onJoin"
@@ -232,6 +241,7 @@ function initials(name: string): string {
               <label class="mb-1 block text-xs text-muted">Your name</label>
               <input
                 v-model="nameDraft"
+                data-test-id="collab-name-input"
                 class="w-full rounded border border-border bg-input px-2 py-1 text-xs text-surface"
                 placeholder="Enter your name"
                 @keydown.enter="onShare"
@@ -239,6 +249,7 @@ function initials(name: string): string {
             </div>
 
             <button
+              data-test-id="collab-share-file"
               class="mb-3 flex h-8 w-full cursor-pointer items-center justify-center gap-1.5 rounded border-none bg-accent text-xs font-medium text-white hover:bg-accent/90 disabled:opacity-50"
               :disabled="!nameDraft.trim()"
               @click="onShare"
@@ -256,11 +267,13 @@ function initials(name: string): string {
             <div class="flex items-center gap-1.5">
               <input
                 v-model="joinInput"
+                data-test-id="collab-join-input"
                 class="min-w-0 flex-1 rounded border border-border bg-input px-2 py-1 text-xs text-surface"
                 placeholder="Paste room link or ID"
                 @keydown.enter="onJoin"
               />
               <button
+                data-test-id="collab-join-room-button"
                 class="flex h-7 cursor-pointer items-center rounded border-none bg-accent px-3 text-xs text-white hover:bg-accent/90 disabled:opacity-50"
                 :disabled="!joinInput.trim() || !nameDraft.trim()"
                 @click="onJoin"
diff --git a/src/components/ColorInput.vue b/src/components/ColorInput.vue
index bb499b1ef..9943f824f 100644
--- a/src/components/ColorInput.vue
+++ b/src/components/ColorInput.vue
@@ -28,6 +28,7 @@ function onHexChange(e: Event) {
     <ColorPicker :color="color" @update="emit('update', $event)" />
     <input
       v-if="editable"
+      data-test-id="color-hex-input"
       class="min-w-0 flex-1 border-none bg-transparent font-mono text-xs text-surface outline-none"
       :value="colorToHexRaw(color)"
       maxlength="6"
diff --git a/src/components/ColorPicker.vue b/src/components/ColorPicker.vue
index 5210eadb2..2727637d4 100644
--- a/src/components/ColorPicker.vue
+++ b/src/components/ColorPicker.vue
@@ -24,6 +24,7 @@ const swatchColor = computed(() => {
   <PopoverRoot>
     <PopoverTrigger as-child>
       <button
+        data-test-id="color-picker-swatch"
         class="size-5 shrink-0 cursor-pointer rounded border border-border p-0"
         :style="{ background: swatchColor }"
       />
@@ -31,6 +32,7 @@ const swatchColor = computed(() => {
 
     <PopoverPortal>
       <PopoverContent
+        data-test-id="color-picker-popover"
         class="z-[100] w-56 rounded-lg border border-border bg-panel p-2 shadow-xl"
         :side-offset="4"
         side="left"
diff --git a/src/components/DesignPanel.vue b/src/components/DesignPanel.vue
index 9e82fa995..1b14bc388 100644
--- a/src/components/DesignPanel.vue
+++ b/src/components/DesignPanel.vue
@@ -28,8 +28,15 @@ const isComponentType = computed(() => {
 
 <template>
   <!-- Multi-select summary -->
-  <div v-if="multiCount > 1" class="flex-1 overflow-x-hidden overflow-y-auto scrollbar-thin pb-4">
-    <div class="flex items-center gap-1.5 border-b border-border px-3 py-2">
+  <div
+    v-if="multiCount > 1"
+    data-test-id="design-panel-multi"
+    class="flex-1 overflow-x-hidden overflow-y-auto scrollbar-thin pb-4"
+  >
+    <div
+      data-test-id="design-multi-header"
+      class="flex items-center gap-1.5 border-b border-border px-3 py-2"
+    >
       <span class="text-[11px] text-muted">Mixed</span>
       <span class="text-xs font-semibold">{{ multiCount }} layers</span>
     </div>
@@ -41,9 +48,15 @@ const isComponentType = computed(() => {
   </div>
 
   <!-- Single selection -->
-  <div v-else-if="node" class="flex-1 overflow-x-hidden overflow-y-auto scrollbar-thin pb-4">
-    <!-- Node header -->
-    <div class="flex items-center gap-1.5 border-b border-border px-3 py-2">
+  <div
+    v-else-if="node"
+    data-test-id="design-panel-single"
+    class="flex-1 overflow-x-hidden overflow-y-auto scrollbar-thin pb-4"
+  >
+    <div
+      data-test-id="design-node-header"
+      class="flex items-center gap-1.5 border-b border-border px-3 py-2"
+    >
       <span class="text-[11px]" :class="isComponentType ? 'text-[#9747ff]' : 'text-muted'">{{
         node.type
       }}</span>
@@ -56,12 +69,14 @@ const isComponentType = computed(() => {
       class="flex flex-col gap-1 border-b border-border px-3 py-2"
     >
       <button
+        data-test-id="design-go-to-component"
         class="rounded bg-[#9747ff]/10 px-2 py-1 text-left text-[11px] text-[#9747ff] hover:bg-[#9747ff]/20"
         @click="store.goToMainComponent()"
       >
         Go to Main Component
       </button>
       <button
+        data-test-id="design-detach-instance"
         class="rounded px-2 py-1 text-left text-[11px] text-muted hover:bg-hover"
         @click="store.detachInstance()"
       >
@@ -80,7 +95,11 @@ const isComponentType = computed(() => {
     <ExportSection />
   </div>
 
-  <div v-else class="flex-1 overflow-x-hidden overflow-y-auto scrollbar-thin pb-4">
+  <div
+    v-else
+    data-test-id="design-panel-empty"
+    class="flex-1 overflow-x-hidden overflow-y-auto scrollbar-thin pb-4"
+  >
     <PageSection />
     <VariablesSection @open-dialog="variablesOpen = true" />
   </div>
diff --git a/src/components/EditorCanvas.vue b/src/components/EditorCanvas.vue
index f8e97df3d..6b9d9ae7a 100644
--- a/src/components/EditorCanvas.vue
+++ b/src/components/EditorCanvas.vue
@@ -40,11 +40,20 @@ const cursor = computed(() => {
 
 <template>
   <CanvasContextMenu>
-    <div class="canvas-area relative flex-1 min-w-0 min-h-0 overflow-hidden">
-      <canvas ref="canvasRef" :style="{ cursor }" class="block size-full touch-none" />
+    <div
+      data-test-id="canvas-area"
+      class="canvas-area relative flex-1 min-w-0 min-h-0 overflow-hidden"
+    >
+      <canvas
+        ref="canvasRef"
+        data-test-id="canvas-element"
+        :style="{ cursor }"
+        class="block size-full touch-none"
+      />
       <Transition leave-active-class="transition-opacity duration-300" leave-to-class="opacity-0">
         <div
           v-if="store.state.loading"
+          data-test-id="canvas-loading"
           class="absolute inset-0 z-50 flex items-center justify-center bg-canvas"
         >
           <svg
diff --git a/src/components/FillPicker.vue b/src/components/FillPicker.vue
index 235f7ed35..3f594ea38 100644
--- a/src/components/FillPicker.vue
+++ b/src/components/FillPicker.vue
@@ -231,6 +231,7 @@ function stopSwatchColor(stop: GradientStop) {
   <PopoverRoot>
     <PopoverTrigger as-child>
       <button
+        data-test-id="fill-picker-swatch"
         class="size-5 shrink-0 cursor-pointer rounded border border-border p-0"
         :style="{ background: swatchBackground }"
       />
@@ -247,6 +248,7 @@ function stopSwatchColor(stop: GradientStop) {
           <button
             class="flex size-6 cursor-pointer items-center justify-center rounded border-none p-0 text-muted transition-colors hover:bg-hover hover:text-surface"
             :class="{ 'bg-hover text-surface': fillCategory === 'SOLID' }"
+            data-test-id="fill-picker-tab-solid"
             title="Solid"
             @click="setCategory('SOLID')"
           >
@@ -257,6 +259,7 @@ function stopSwatchColor(stop: GradientStop) {
           <button
             class="flex size-6 cursor-pointer items-center justify-center rounded border-none p-0 text-muted transition-colors hover:bg-hover hover:text-surface"
             :class="{ 'bg-hover text-surface': fillCategory === 'GRADIENT' }"
+            data-test-id="fill-picker-tab-gradient"
             title="Gradient"
             @click="setCategory('GRADIENT')"
           >
@@ -273,6 +276,7 @@ function stopSwatchColor(stop: GradientStop) {
           <button
             class="flex size-6 cursor-pointer items-center justify-center rounded border-none p-0 text-muted transition-colors hover:bg-hover hover:text-surface"
             :class="{ 'bg-hover text-surface': fillCategory === 'IMAGE' }"
+            data-test-id="fill-picker-tab-image"
             title="Image"
             @click="setCategory('IMAGE')"
           >
@@ -319,6 +323,7 @@ function stopSwatchColor(stop: GradientStop) {
         <div
           v-if="isGradient && fill.gradientStops?.length"
           ref="gradientStopBarRef"
+          data-test-id="fill-picker-gradient-bar"
           class="relative mb-2 h-6 rounded"
           :style="{ background: gradientBarBackground }"
           @pointermove="onStopBarPointerMove"
@@ -343,6 +348,7 @@ function stopSwatchColor(stop: GradientStop) {
             <span class="text-[11px] text-muted">Stops</span>
             <button
               class="flex size-4 cursor-pointer items-center justify-center rounded border-none bg-transparent p-0 text-muted hover:text-surface"
+              data-test-id="fill-picker-add-stop"
               title="Add stop"
               @click="addStop"
             >
@@ -399,6 +405,7 @@ function stopSwatchColor(stop: GradientStop) {
         <!-- Image placeholder -->
         <div
           v-if="fill.type === 'IMAGE'"
+          data-test-id="fill-picker-image-placeholder"
           class="flex h-24 items-center justify-center rounded border border-dashed border-border text-xs text-muted"
         >
           Image fill (coming soon)
diff --git a/src/components/FontPicker.vue b/src/components/FontPicker.vue
index 1478b8f8b..0a0fdb1bf 100644
--- a/src/components/FontPicker.vue
+++ b/src/components/FontPicker.vue
@@ -50,6 +50,7 @@ function onSelect(val: string) {
   <PopoverRoot v-model:open="open">
     <PopoverAnchor>
       <button
+        data-test-id="font-picker-trigger"
         class="flex w-full cursor-pointer items-center justify-between rounded border border-border bg-input px-2 py-1 text-xs text-surface hover:bg-hover"
         @click="open = !open"
       >
@@ -69,6 +70,7 @@ function onSelect(val: string) {
           <ListboxFilter
             ref="filterRef"
             v-model="searchTerm"
+            data-test-id="font-picker-search"
             class="min-w-0 flex-1 border-none bg-transparent text-xs text-surface outline-none placeholder:text-muted"
             placeholder="Search fonts…"
             autocomplete="off"
@@ -86,6 +88,7 @@ function onSelect(val: string) {
           >
             <ListboxItem
               :value="option"
+              data-test-id="font-picker-item"
               class="flex w-full cursor-pointer items-center gap-2 px-2 py-2 text-sm text-surface outline-none data-[highlighted]:bg-hover"
               :style="{ fontFamily: `'${option}', sans-serif` }"
             >
diff --git a/src/components/HsvColorArea.vue b/src/components/HsvColorArea.vue
index ef304945f..450fac8fb 100644
--- a/src/components/HsvColorArea.vue
+++ b/src/components/HsvColorArea.vue
@@ -131,6 +131,7 @@ const hueColor = computed(() => {
   <!-- SV area -->
   <div
     ref="svAreaRef"
+    data-test-id="hsv-sv-area"
     class="relative h-[140px] w-full cursor-crosshair overflow-hidden rounded"
     :style="{ background: hueColor }"
     @pointerdown="onSvPointerDown"
@@ -146,7 +147,15 @@ const hueColor = computed(() => {
 
   <!-- Hue slider -->
   <div class="mt-2">
-    <input type="range" class="hue-slider" :value="hue" min="0" max="360" @input="onHueInput" />
+    <input
+      type="range"
+      data-test-id="hsv-hue-slider"
+      class="hue-slider"
+      :value="hue"
+      min="0"
+      max="360"
+      @input="onHueInput"
+    />
   </div>
 
   <!-- Alpha slider -->
@@ -157,6 +166,7 @@ const hueColor = computed(() => {
     />
     <input
       type="range"
+      data-test-id="hsv-alpha-slider"
       class="alpha-slider"
       :value="alpha * 100"
       min="0"
@@ -170,6 +180,7 @@ const hueColor = computed(() => {
     <span class="text-[11px] text-muted">#</span>
     <input
       type="text"
+      data-test-id="hsv-hex-input"
       class="min-w-0 flex-1 rounded border border-border bg-input px-1.5 py-0.5 font-mono text-xs text-surface"
       :value="hexValue"
       maxlength="6"
@@ -177,6 +188,7 @@ const hueColor = computed(() => {
     />
     <input
       type="number"
+      data-test-id="hsv-alpha-input"
       class="w-10 rounded border border-border bg-input px-1 py-0.5 text-right text-xs text-surface"
       :value="Math.round(alpha * 100)"
       min="0"
diff --git a/src/components/LayersPanel.vue b/src/components/LayersPanel.vue
index a24b9c0dd..30a39befa 100644
--- a/src/components/LayersPanel.vue
+++ b/src/components/LayersPanel.vue
@@ -260,6 +260,7 @@ function updateDropTarget(ev: PointerEvent) {
 
 <template>
   <aside
+    data-test-id="layers-panel"
     class="flex min-w-0 flex-1 flex-col overflow-hidden border-r border-border bg-panel"
     style="contain: paint layout style"
   >
@@ -279,12 +280,19 @@ function updateDropTarget(ev: PointerEvent) {
         />
       </SplitterResizeHandle>
       <SplitterPanel :default-size="70" :min-size="20" class="flex flex-col overflow-hidden">
-        <header class="shrink-0 px-3 py-2 text-[11px] uppercase tracking-wider text-muted">
+        <header
+          data-test-id="layers-header"
+          class="shrink-0 px-3 py-2 text-[11px] uppercase tracking-wider text-muted"
+        >
           Layers
         </header>
         <ContextMenuRoot :modal="false">
           <ContextMenuTrigger as-child @contextmenu="onLayerRightClick">
-            <div ref="listRef" class="relative flex-1 overflow-y-auto scrollbar-thin px-1">
+            <div
+              ref="listRef"
+              data-test-id="layers-tree"
+              class="relative flex-1 overflow-y-auto scrollbar-thin px-1"
+            >
               <TreeRoot
                 :key="treeKey"
                 v-slot="{ flattenItems }"
@@ -301,6 +309,7 @@ function updateDropTarget(ev: PointerEvent) {
                 >
                   <TreeItem v-slot="{ isExpanded }" v-bind="item.bind" as-child @select="onSelect">
                     <button
+                      data-test-id="layers-item"
                       class="group/row flex w-full cursor-pointer items-center gap-1 rounded border-none py-1 text-left text-xs"
                       :class="[
                         store.state.selectedIds.has(item.value.id)
diff --git a/src/components/NodeContextMenuContent.vue b/src/components/NodeContextMenuContent.vue
index 5b0fa451b..1e6463351 100644
--- a/src/components/NodeContextMenuContent.vue
+++ b/src/components/NodeContextMenuContent.vue
@@ -72,6 +72,7 @@ const menuClass =
 <template>
   <ContextMenuContent :class="menuClass" :side-offset="2" align="start">
     <ContextMenuItem
+      data-test-id="context-copy"
       :class="itemClass"
       :disabled="!hasSelection"
       @select="document.execCommand('copy')"
@@ -80,6 +81,7 @@ const menuClass =
       <span class="text-[11px] text-muted">⌘C</span>
     </ContextMenuItem>
     <ContextMenuItem
+      data-test-id="context-cut"
       :class="itemClass"
       :disabled="!hasSelection"
       @select="document.execCommand('cut')"
@@ -87,11 +89,16 @@ const menuClass =
       <span>Cut</span>
       <span class="text-[11px] text-muted">⌘X</span>
     </ContextMenuItem>
-    <ContextMenuItem :class="itemClass" @select="document.execCommand('paste')">
+    <ContextMenuItem
+      data-test-id="context-paste"
+      :class="itemClass"
+      @select="document.execCommand('paste')"
+    >
       <span>Paste here</span>
       <span class="text-[11px] text-muted">⌘V</span>
     </ContextMenuItem>
     <ContextMenuItem
+      data-test-id="context-duplicate"
       :class="itemClass"
       :disabled="!hasSelection"
       @select="store.duplicateSelected()"
@@ -99,7 +106,12 @@ const menuClass =
       <span>Duplicate</span>
       <span class="text-[11px] text-muted">⌘D</span>
     </ContextMenuItem>
-    <ContextMenuItem :class="itemClass" :disabled="!hasSelection" @select="store.deleteSelected()">
+    <ContextMenuItem
+      data-test-id="context-delete"
+      :class="itemClass"
+      :disabled="!hasSelection"
+      @select="store.deleteSelected()"
+    >
       <span>Delete</span>
       <span class="text-[11px] text-muted">⌫</span>
     </ContextMenuItem>
@@ -107,7 +119,7 @@ const menuClass =
     <ContextMenuSeparator class="my-1 h-px bg-border" />
 
     <ContextMenuSub v-if="otherPages.length > 0 && hasSelection">
-      <ContextMenuSubTrigger :class="itemClass">
+      <ContextMenuSubTrigger data-test-id="context-move-to-page" :class="itemClass">
         <span>Move to page</span>
         <span class="text-sm text-muted">›</span>
       </ContextMenuSubTrigger>
@@ -125,26 +137,51 @@ const menuClass =
       </ContextMenuPortal>
     </ContextMenuSub>
 
-    <ContextMenuItem :class="itemClass" :disabled="!hasSelection" @select="store.bringToFront()">
+    <ContextMenuItem
+      data-test-id="context-bring-to-front"
+      :class="itemClass"
+      :disabled="!hasSelection"
+      @select="store.bringToFront()"
+    >
       <span>Bring to front</span>
       <span class="text-[11px] text-muted">]</span>
     </ContextMenuItem>
-    <ContextMenuItem :class="itemClass" :disabled="!hasSelection" @select="store.sendToBack()">
+    <ContextMenuItem
+      data-test-id="context-send-to-back"
+      :class="itemClass"
+      :disabled="!hasSelection"
+      @select="store.sendToBack()"
+    >
       <span>Send to back</span>
       <span class="text-[11px] text-muted">[</span>
     </ContextMenuItem>
 
     <ContextMenuSeparator class="my-1 h-px bg-border" />
 
-    <ContextMenuItem :class="itemClass" :disabled="multiCount < 2" @select="store.groupSelected()">
+    <ContextMenuItem
+      data-test-id="context-group"
+      :class="itemClass"
+      :disabled="multiCount < 2"
+      @select="store.groupSelected()"
+    >
       <span>Group</span>
       <span class="text-[11px] text-muted">⌘G</span>
     </ContextMenuItem>
-    <ContextMenuItem v-if="isGroup" :class="itemClass" @select="store.ungroupSelected()">
+    <ContextMenuItem
+      v-if="isGroup"
+      data-test-id="context-ungroup"
+      :class="itemClass"
+      @select="store.ungroupSelected()"
+    >
       <span>Ungroup</span>
       <span class="text-[11px] text-muted">⇧⌘G</span>
     </ContextMenuItem>
-    <ContextMenuItem v-if="hasSelection" :class="itemClass" @select="store.wrapInAutoLayout()">
+    <ContextMenuItem
+      v-if="hasSelection"
+      data-test-id="context-auto-layout"
+      :class="itemClass"
+      @select="store.wrapInAutoLayout()"
+    >
       <span>Add auto layout</span>
       <span class="text-[11px] text-muted">⇧A</span>
     </ContextMenuItem>
@@ -152,6 +189,7 @@ const menuClass =
     <ContextMenuSeparator class="my-1 h-px bg-border" />
 
     <ContextMenuItem
+      data-test-id="context-create-component"
       :class="componentItemClass"
       :disabled="!hasSelection"
       @select="store.createComponentFromSelection()"
@@ -161,6 +199,7 @@ const menuClass =
     </ContextMenuItem>
     <ContextMenuItem
       v-if="canCreateComponentSet"
+      data-test-id="context-create-component-set"
       :class="componentItemClass"
       @select="store.createComponentSetFromComponents()"
     >
@@ -169,6 +208,7 @@ const menuClass =
     </ContextMenuItem>
     <ContextMenuItem
       v-if="isComponent"
+      data-test-id="context-create-instance"
       :class="componentItemClass"
       @select="store.createInstanceFromComponent(singleNode!.id)"
     >
@@ -176,12 +216,18 @@ const menuClass =
     </ContextMenuItem>
     <ContextMenuItem
       v-if="isInstance"
+      data-test-id="context-go-to-component"
       :class="componentItemClass"
       @select="store.goToMainComponent()"
     >
       <span>Go to main component</span>
     </ContextMenuItem>
-    <ContextMenuItem v-if="isInstance" :class="itemClass" @select="store.detachInstance()">
+    <ContextMenuItem
+      v-if="isInstance"
+      data-test-id="context-detach-instance"
+      :class="itemClass"
+      @select="store.detachInstance()"
+    >
       <span>Detach instance</span>
       <span class="text-[11px] text-muted">⌥⌘B</span>
     </ContextMenuItem>
@@ -189,18 +235,30 @@ const menuClass =
     <template v-if="hasSelection">
       <ContextMenuSeparator class="my-1 h-px bg-border" />
 
-      <ContextMenuItem :class="itemClass" @select="store.toggleVisibility()">
+      <ContextMenuItem
+        data-test-id="context-toggle-visibility"
+        :class="itemClass"
+        @select="store.toggleVisibility()"
+      >
         <span>{{ isVisible ? 'Hide' : 'Show' }}</span>
         <span class="text-[11px] text-muted">⇧⌘H</span>
       </ContextMenuItem>
-      <ContextMenuItem :class="itemClass" @select="store.toggleLock()">
+      <ContextMenuItem
+        data-test-id="context-toggle-lock"
+        :class="itemClass"
+        @select="store.toggleLock()"
+      >
         <span>{{ isLocked ? 'Unlock' : 'Lock' }}</span>
         <span class="text-[11px] text-muted">⇧⌘L</span>
       </ContextMenuItem>
 
       <ContextMenuSeparator class="my-1 h-px bg-border" />
 
-      <ContextMenuItem :class="itemClass" @select="store.exportSelection(1, 'PNG')">
+      <ContextMenuItem
+        data-test-id="context-export-png"
+        :class="itemClass"
+        @select="store.exportSelection(1, 'PNG')"
+      >
         <span>Export as PNG</span>
         <span class="text-[11px] text-muted">⇧⌘E</span>
       </ContextMenuItem>
diff --git a/src/components/PagesPanel.vue b/src/components/PagesPanel.vue
index 534a45c60..ecde18b9f 100644
--- a/src/components/PagesPanel.vue
+++ b/src/components/PagesPanel.vue
@@ -44,10 +44,13 @@ function onKeydown(e: KeyboardEvent, pageId: string) {
 </script>
 
 <template>
-  <div class="flex min-h-0 flex-1 flex-col">
+  <div data-test-id="pages-panel" class="flex min-h-0 flex-1 flex-col">
     <div class="flex shrink-0 items-center justify-between px-3 py-1.5">
-      <span class="text-[11px] uppercase tracking-wider text-muted">Pages</span>
+      <span data-test-id="pages-header" class="text-[11px] uppercase tracking-wider text-muted"
+        >Pages</span
+      >
       <button
+        data-test-id="pages-add"
         class="cursor-pointer rounded border-none bg-transparent px-1 text-base leading-none text-muted hover:bg-hover hover:text-surface"
         title="Add page"
         @click="store.addPage()"
@@ -60,6 +63,7 @@ function onKeydown(e: KeyboardEvent, pageId: string) {
         <input
           v-if="editingPageId === pg.id"
           data-page-edit
+          data-test-id="pages-item-input"
           class="w-full rounded border border-accent bg-input px-2 py-1 text-xs text-surface outline-none"
           :value="pg.name"
           @blur="commitRename(pg.id, $event.target as HTMLInputElement)"
@@ -74,6 +78,7 @@ function onKeydown(e: KeyboardEvent, pageId: string) {
         </div>
         <button
           v-else
+          data-test-id="pages-item"
           class="flex w-full cursor-pointer items-center gap-1.5 rounded border-none px-2 py-1 text-left text-xs"
           :class="
             pg.id === store.state.currentPageId
diff --git a/src/components/PropertiesPanel.vue b/src/components/PropertiesPanel.vue
index a2353beff..31a2bf0a8 100644
--- a/src/components/PropertiesPanel.vue
+++ b/src/components/PropertiesPanel.vue
@@ -14,6 +14,7 @@ const { activeTab } = useAIChat()
 
 <template>
   <aside
+    data-test-id="properties-panel"
     class="flex min-w-0 flex-1 flex-col overflow-hidden border-l border-border bg-panel"
     style="contain: paint layout style"
   >
@@ -21,12 +22,14 @@ const { activeTab } = useAIChat()
       <TabsList class="flex h-10 shrink-0 items-center gap-1 border-b border-border px-2">
         <TabsTrigger
           value="design"
+          data-test-id="properties-tab-design"
           class="rounded px-2.5 py-1 text-xs text-muted hover:text-surface data-[state=active]:font-semibold data-[state=active]:text-surface"
         >
           Design
         </TabsTrigger>
         <TabsTrigger
           value="code"
+          data-test-id="properties-tab-code"
           class="flex items-center gap-1 rounded px-2.5 py-1 text-xs text-muted hover:text-surface data-[state=active]:font-semibold data-[state=active]:text-surface"
         >
           <icon-lucide-code class="size-3" />
@@ -34,6 +37,7 @@ const { activeTab } = useAIChat()
         </TabsTrigger>
         <TabsTrigger
           value="ai"
+          data-test-id="properties-tab-ai"
           class="flex items-center gap-1 rounded px-2.5 py-1 text-xs text-muted hover:text-surface data-[state=active]:font-semibold data-[state=active]:text-surface"
         >
           <icon-lucide-sparkles class="size-3" />
@@ -41,6 +45,7 @@ const { activeTab } = useAIChat()
         </TabsTrigger>
         <span
           v-if="activeTab === 'design'"
+          data-test-id="properties-zoom"
           class="ml-auto cursor-pointer rounded px-1.5 py-0.5 text-[11px] text-muted hover:bg-hover"
         >
           {{ Math.round(store.state.zoom * 100) }}%
diff --git a/src/components/SafariBanner.vue b/src/components/SafariBanner.vue
index bc75d8d7e..4dfdfd468 100644
--- a/src/components/SafariBanner.vue
+++ b/src/components/SafariBanner.vue
@@ -10,6 +10,7 @@ const show = !IS_TAURI && typeof window !== 'undefined' && !window.showSaveFileP
 <template>
   <div
     v-if="show && !dismissed"
+    data-test-id="safari-banner"
     class="flex items-center gap-2 border-b border-amber-500/30 bg-amber-500/10 px-3 py-1.5 text-xs text-amber-200"
   >
     <span class="flex-1">
@@ -19,6 +20,7 @@ const show = !IS_TAURI && typeof window !== 'undefined' && !window.showSaveFileP
       Edge for full support.
     </span>
     <button
+      data-test-id="safari-banner-dismiss"
       class="shrink-0 rounded px-1.5 py-0.5 text-amber-300 transition-colors hover:bg-amber-500/20"
       @click="dismissed = true"
     >
diff --git a/src/components/ScrubInput.vue b/src/components/ScrubInput.vue
index 8e4bb22f8..4b506d693 100644
--- a/src/components/ScrubInput.vue
+++ b/src/components/ScrubInput.vue
@@ -111,6 +111,7 @@ function onKeydown(e: KeyboardEvent) {
 
 <template>
   <div
+    data-test-id="scrub-input"
     class="flex min-w-0 flex-1 items-center rounded border border-border bg-input h-[26px] focus-within:border-accent"
     :style="{ cursor: editing ? 'auto' : 'ew-resize' }"
     @pointerdown="!editing && startScrub($event)"
@@ -127,6 +128,7 @@ function onKeydown(e: KeyboardEvent) {
       v-if="editing"
       ref="inputRef"
       type="number"
+      data-test-id="scrub-input-field"
       class="min-w-0 flex-1 cursor-text border-none bg-transparent pr-1.5 font-[inherit] text-xs text-surface outline-none"
       :value="isMixed ? '' : displayValue"
       :placeholder="placeholder"
diff --git a/src/components/TabBar.vue b/src/components/TabBar.vue
index 697d5257f..c5a5e24bf 100644
--- a/src/components/TabBar.vue
+++ b/src/components/TabBar.vue
@@ -36,12 +36,14 @@ function onClose(e: MouseEvent, tabId: string) {
         v-for="tab in tabs"
         :key="tab.id"
         :value="tab.id"
+        data-test-id="tabbar-tab"
         class="group/tab flex h-full max-w-48 min-w-0 cursor-pointer items-center gap-1.5 border-r border-border px-3 text-xs transition-colors select-none outline-none focus-visible:ring-1 focus-visible:ring-accent data-[state=active]:bg-panel data-[state=active]:text-surface data-[state=inactive]:text-muted data-[state=inactive]:hover:text-surface"
         @mousedown="onMiddleClick($event, tab.id)"
       >
         <icon-lucide-file class="size-3 shrink-0 opacity-50" />
         <span class="min-w-0 flex-1 truncate">{{ tab.name }}</span>
         <button
+          data-test-id="tabbar-close"
           class="flex size-4 shrink-0 cursor-pointer items-center justify-center rounded opacity-0 transition-opacity hover:bg-hover group-hover/tab:opacity-100 data-[state=active]:opacity-100"
           :class="tab.isActive ? 'opacity-100' : ''"
           :title="`Close ${tab.name}`"
@@ -54,6 +56,7 @@ function onClose(e: MouseEvent, tabId: string) {
       </TabsTrigger>
     </TabsList>
     <button
+      data-test-id="tabbar-new"
       class="flex size-9 shrink-0 cursor-pointer items-center justify-center text-muted transition-colors hover:text-surface"
       title="New tab"
       aria-label="New tab"
diff --git a/src/components/Toolbar.vue b/src/components/Toolbar.vue
index 23b4df6ad..f57f4bc0a 100644
--- a/src/components/Toolbar.vue
+++ b/src/components/Toolbar.vue
@@ -81,11 +81,15 @@ function activeKeyForTool(tool: (typeof TOOLS)[number]): Tool {
 
 <template>
   <div class="absolute bottom-4 left-1/2 z-10 flex -translate-x-1/2 items-center">
-    <div class="flex gap-0.5 rounded-xl border border-border bg-panel p-1 shadow-lg">
+    <div
+      data-test-id="toolbar"
+      class="flex gap-0.5 rounded-xl border border-border bg-panel p-1 shadow-lg"
+    >
       <template v-for="tool in TOOLS" :key="tool.key">
         <!-- Tool with flyout: split button + chevron -->
         <div v-if="tool.flyout && tool.flyout.length > 1" class="flex items-center">
           <button
+            :data-test-id="`toolbar-tool-${activeKeyForTool(tool).toLowerCase()}`"
             class="flex size-8 cursor-pointer items-center justify-center rounded-lg border-none transition-colors"
             :class="
               isActive(tool)
@@ -101,6 +105,7 @@ function activeKeyForTool(tool: (typeof TOOLS)[number]): Tool {
           <DropdownMenuRoot>
             <DropdownMenuTrigger as-child>
               <button
+                :data-test-id="`toolbar-flyout-${tool.key.toLowerCase()}`"
                 class="flex h-8 w-3 cursor-pointer items-center justify-center rounded-lg border-none transition-colors"
                 :class="
                   isActive(tool)
@@ -122,6 +127,7 @@ function activeKeyForTool(tool: (typeof TOOLS)[number]): Tool {
                 <DropdownMenuItem
                   v-for="sub in tool.flyout"
                   :key="sub"
+                  :data-test-id="`toolbar-flyout-item-${sub.toLowerCase()}`"
                   class="flex cursor-pointer items-center gap-2 rounded-md px-2 py-1.5 text-xs outline-none transition-colors"
                   :class="
                     store.state.activeTool === sub
@@ -144,6 +150,7 @@ function activeKeyForTool(tool: (typeof TOOLS)[number]): Tool {
         <!-- Simple tool button -->
         <button
           v-else
+          :data-test-id="`toolbar-tool-${tool.key.toLowerCase()}`"
           class="flex size-8 cursor-pointer items-center justify-center rounded-lg border-none transition-colors"
           :class="
             isActive(tool)
diff --git a/src/components/VariablesDialog.vue b/src/components/VariablesDialog.vue
index 45709303a..4e3428d6d 100644
--- a/src/components/VariablesDialog.vue
+++ b/src/components/VariablesDialog.vue
@@ -378,6 +378,7 @@ const table = useVueTable({
     <DialogPortal>
       <DialogOverlay class="fixed inset-0 z-40 bg-black/50" />
       <DialogContent
+        data-test-id="variables-dialog"
         class="fixed left-1/2 top-1/2 z-50 flex h-[75vh] w-[800px] max-w-[90vw] -translate-x-1/2 -translate-y-1/2 flex-col rounded-xl border border-border bg-panel shadow-2xl outline-none"
       >
         <div v-if="collections.length === 0" class="flex flex-1 flex-col">
@@ -393,6 +394,7 @@ const table = useVueTable({
             <div class="text-center">
               <p class="text-sm text-muted">No variable collections</p>
               <button
+                data-test-id="variables-create-collection"
                 class="mt-2 cursor-pointer rounded bg-hover px-3 py-1.5 text-xs text-surface hover:bg-border"
                 @click="addCollection"
               >
@@ -420,6 +422,7 @@ const table = useVueTable({
                   <TabsTrigger
                     v-else
                     :value="col.id"
+                    data-test-id="variables-collection-tab"
                     class="cursor-pointer whitespace-nowrap rounded border-none px-2.5 py-1 text-xs text-muted data-[state=active]:bg-hover data-[state=active]:text-surface"
                     @dblclick="startRenameCollection(col.id)"
                   >
@@ -438,6 +441,7 @@ const table = useVueTable({
                   />
                 </div>
                 <button
+                  data-test-id="variables-add-collection"
                   class="flex size-6 cursor-pointer items-center justify-center rounded border-none bg-transparent text-muted hover:bg-hover hover:text-surface"
                   title="Add collection"
                   @click="addCollection"
@@ -521,6 +525,7 @@ const table = useVueTable({
 
               <!-- Footer -->
               <button
+                data-test-id="variables-add-variable"
                 class="flex w-full shrink-0 cursor-pointer items-center gap-1.5 border-t border-border bg-transparent px-4 py-2 text-xs text-muted hover:bg-hover hover:text-surface"
                 @click="addVariable"
               >
diff --git a/src/components/chat/APIKeySetup.vue b/src/components/chat/APIKeySetup.vue
index 0dd9c3263..e7ac18ff2 100644
--- a/src/components/chat/APIKeySetup.vue
+++ b/src/components/chat/APIKeySetup.vue
@@ -14,18 +14,23 @@ function save() {
 </script>
 
 <template>
-  <div class="flex flex-1 flex-col items-center justify-center gap-4 px-4">
+  <div
+    data-test-id="api-key-setup"
+    class="flex flex-1 flex-col items-center justify-center gap-4 px-4"
+  >
     <icon-lucide-key-round class="size-8 text-muted" />
     <p class="text-center text-xs text-muted">Enter your OpenRouter API key to start chatting.</p>
     <form class="flex w-full gap-1.5" @submit.prevent="save">
       <input
         v-model="input"
         type="password"
+        data-test-id="api-key-input"
         placeholder="sk-or-…"
         class="min-w-0 flex-1 rounded border border-border bg-input px-2 py-1 text-xs text-surface outline-none focus:border-accent"
       />
       <button
         type="submit"
+        data-test-id="api-key-save"
         class="shrink-0 rounded bg-accent px-2.5 py-1 text-xs font-medium text-white hover:bg-accent/90"
         :disabled="!input.trim()"
       >
@@ -35,6 +40,7 @@ function save() {
     <a
       href="https://openrouter.ai/keys"
       target="_blank"
+      data-test-id="api-key-get-link"
       class="text-[10px] text-muted underline hover:text-surface"
     >
       Get an API key →
diff --git a/src/components/chat/ChatInput.vue b/src/components/chat/ChatInput.vue
index 69fb9392b..09730fadf 100644
--- a/src/components/chat/ChatInput.vue
+++ b/src/components/chat/ChatInput.vue
@@ -51,6 +51,7 @@ function handleSubmit(e: Event) {
       <div class="mb-1.5 flex items-center">
         <SelectRoot v-model="modelId">
           <SelectTrigger
+            data-test-id="chat-model-selector"
             class="flex items-center gap-1 rounded px-1.5 py-0.5 text-[10px] text-muted hover:bg-hover hover:text-surface"
           >
             <icon-lucide-bot class="size-3" />
@@ -90,6 +91,7 @@ function handleSubmit(e: Event) {
         <input
           v-model="input"
           type="text"
+          data-test-id="chat-input"
           placeholder="Describe a change…"
           class="min-w-0 flex-1 rounded border border-border bg-input px-2.5 py-1.5 text-xs text-surface outline-none placeholder:text-muted focus:border-accent"
           :disabled="status === 'submitted'"
@@ -98,6 +100,7 @@ function handleSubmit(e: Event) {
           <TooltipTrigger as-child>
             <button
               type="button"
+              data-test-id="chat-stop-button"
               class="shrink-0 rounded border border-border px-2 py-1.5 text-xs text-muted hover:bg-hover"
               @click="emit('stop')"
             >
@@ -118,6 +121,7 @@ function handleSubmit(e: Event) {
           <TooltipTrigger as-child>
             <button
               type="submit"
+              data-test-id="chat-send-button"
               class="shrink-0 rounded bg-accent px-2.5 py-1.5 text-xs font-medium text-white hover:bg-accent/90"
               :disabled="!input.trim()"
             >
diff --git a/src/components/chat/ChatMessage.vue b/src/components/chat/ChatMessage.vue
index b6f521552..4f80f548a 100644
--- a/src/components/chat/ChatMessage.vue
+++ b/src/components/chat/ChatMessage.vue
@@ -55,11 +55,15 @@ function toolState(part: ToolPart): 'pending' | 'done' | 'error' {
 </script>
 
 <template>
-  <div :class="message.role === 'user' ? 'flex justify-end' : ''">
+  <div
+    :data-test-id="`chat-message-${message.role}`"
+    :class="message.role === 'user' ? 'flex justify-end' : ''"
+  >
     <div class="min-w-0 space-y-1.5" :class="message.role === 'user' ? 'max-w-[85%]' : ''">
       <!-- Tool timeline -->
       <div
         v-if="message.role === 'assistant' && getToolParts(message).length > 0"
+        data-test-id="chat-tool-timeline"
         class="space-y-0.5 rounded-lg border border-border bg-canvas p-2"
       >
         <CollapsibleRoot v-for="tool in getToolParts(message)" :key="tool.toolCallId">
@@ -114,6 +118,7 @@ function toolState(part: ToolPart): 'pending' | 'done' | 'error' {
       <!-- Text bubble -->
       <div
         v-if="getTextContent(message)"
+        data-test-id="chat-text-bubble"
         class="rounded-xl px-3 py-2 text-xs leading-relaxed"
         :class="
           message.role === 'user'
diff --git a/src/components/properties/AppearanceSection.vue b/src/components/properties/AppearanceSection.vue
index 57284aa78..d86312a00 100644
--- a/src/components/properties/AppearanceSection.vue
+++ b/src/components/properties/AppearanceSection.vue
@@ -147,10 +147,11 @@ const cornerRadiusValue = computed(() => {
 </script>
 
 <template>
-  <div v-if="active" class="border-b border-border px-3 py-2">
+  <div v-if="active" data-test-id="appearance-section" class="border-b border-border px-3 py-2">
     <div class="mb-1.5 flex items-center justify-between">
       <label class="text-[11px] text-muted">Appearance</label>
       <button
+        data-test-id="appearance-visibility"
         class="flex cursor-pointer items-center justify-center rounded border-none bg-transparent p-0.5 text-muted hover:bg-hover hover:text-surface"
         :class="{ 'text-accent': visibilityState === 'hidden' }"
         title="Toggle visibility"
diff --git a/src/components/properties/EffectsSection.vue b/src/components/properties/EffectsSection.vue
index 3ba7522bd..ddd9fbc4c 100644
--- a/src/components/properties/EffectsSection.vue
+++ b/src/components/properties/EffectsSection.vue
@@ -143,10 +143,11 @@ function toggleExpand(index: number) {
 </script>
 
 <template>
-  <div v-if="active" class="border-b border-border px-3 py-2">
+  <div v-if="active" data-test-id="effects-section" class="border-b border-border px-3 py-2">
     <div class="flex items-center justify-between">
       <label class="mb-1 block text-[11px] text-muted">Effects</label>
       <button
+        data-test-id="effects-section-add"
         class="flex size-5 cursor-pointer items-center justify-center rounded border-none bg-transparent text-sm leading-none text-muted hover:bg-hover hover:text-surface"
         @click="add"
       >
@@ -156,7 +157,12 @@ function toggleExpand(index: number) {
 
     <p v-if="effectsAreMixed" class="text-[11px] text-muted">Click + to replace mixed effects</p>
 
-    <div v-for="(effect, i) in effectsAreMixed ? [] : ((node ?? nodes[0])?.effects ?? [])" :key="i">
+    <div
+      v-for="(effect, i) in effectsAreMixed ? [] : ((node ?? nodes[0])?.effects ?? [])"
+      :key="i"
+      data-test-id="effects-item"
+      :data-test-index="i"
+    >
       <!-- Collapsed row: color swatch | type dropdown | eye | minus -->
       <div class="group flex items-center gap-1.5 py-0.5">
         <button
diff --git a/src/components/properties/ExportSection.vue b/src/components/properties/ExportSection.vue
index 3d9536b82..1c4ec9145 100644
--- a/src/components/properties/ExportSection.vue
+++ b/src/components/properties/ExportSection.vue
@@ -95,10 +95,11 @@ onUnmounted(() => {
 </script>
 
 <template>
-  <div class="border-b border-border px-3 py-2">
+  <div data-test-id="export-section" class="border-b border-border px-3 py-2">
     <div class="flex items-center justify-between">
       <label class="mb-1 block text-[11px] text-muted">Export</label>
       <button
+        data-test-id="export-section-add"
         class="flex size-5 cursor-pointer items-center justify-center rounded border-none bg-transparent text-sm leading-none text-muted hover:bg-hover hover:text-surface"
         @click="addSetting"
       >
@@ -106,7 +107,13 @@ onUnmounted(() => {
       </button>
     </div>
 
-    <div v-for="(setting, i) in settings" :key="i" class="flex items-center gap-1.5 py-0.5">
+    <div
+      v-for="(setting, i) in settings"
+      :key="i"
+      data-test-id="export-item"
+      :data-test-index="i"
+      class="flex items-center gap-1.5 py-0.5"
+    >
       <AppSelect
         :model-value="setting.scale"
         :options="SCALE_OPTIONS"
@@ -128,6 +135,7 @@ onUnmounted(() => {
 
     <button
       v-if="settings.length > 0"
+      data-test-id="export-button"
       class="mt-1.5 w-full cursor-pointer truncate rounded bg-blue-600 px-3 py-1.5 text-xs font-medium text-white hover:bg-blue-700 disabled:cursor-default disabled:opacity-50"
       :disabled="exporting"
       @click="doExport"
@@ -137,6 +145,7 @@ onUnmounted(() => {
 
     <button
       v-if="settings.length > 0"
+      data-test-id="export-preview-toggle"
       class="mt-1 flex w-full cursor-pointer items-center gap-1 rounded border-none bg-transparent px-0 py-1 text-[11px] text-muted hover:text-surface"
       @click="showPreview = !showPreview"
     >
diff --git a/src/components/properties/FillSection.vue b/src/components/properties/FillSection.vue
index f468318f1..51754403f 100644
--- a/src/components/properties/FillSection.vue
+++ b/src/components/properties/FillSection.vue
@@ -116,10 +116,11 @@ const filteredVariables = computed(() => {
 </script>
 
 <template>
-  <div v-if="active" class="border-b border-border px-3 py-2">
+  <div v-if="active" data-test-id="fill-section" class="border-b border-border px-3 py-2">
     <div class="flex items-center justify-between">
       <label class="mb-1 block text-[11px] text-muted">Fill</label>
       <button
+        data-test-id="fill-section-add"
         class="flex size-5 cursor-pointer items-center justify-center rounded border-none bg-transparent text-sm leading-none text-muted hover:bg-hover hover:text-surface"
         @click="add"
       >
@@ -130,6 +131,8 @@ const filteredVariables = computed(() => {
     <div
       v-for="(fill, i) in fillsAreMixed ? [] : (activeNode?.fills ?? [])"
       :key="i"
+      data-test-id="fill-item"
+      :data-test-index="i"
       class="group flex items-center gap-1.5 py-0.5"
     >
       <FillPicker :fill="fill" @update="updateFill(i, $event)" />
@@ -142,6 +145,7 @@ const filteredVariables = computed(() => {
           {{ getBoundVariable(i)!.name }}
         </span>
         <button
+          data-test-id="fill-unbind-variable"
           class="cursor-pointer border-none bg-transparent p-0 text-violet-400 hover:text-surface"
           title="Detach variable"
           @click="unbindVariable(i)"
diff --git a/src/components/properties/LayoutSection.vue b/src/components/properties/LayoutSection.vue
index 3ba1a6152..637c85586 100644
--- a/src/components/properties/LayoutSection.vue
+++ b/src/components/properties/LayoutSection.vue
@@ -126,7 +126,7 @@ function setAlignment(primary: LayoutAlign, counter: LayoutCounterAlign) {
 </script>
 
 <template>
-  <div v-if="node" class="border-b border-border px-3 py-2">
+  <div v-if="node" data-test-id="layout-section" class="border-b border-border px-3 py-2">
     <label class="mb-1.5 block text-[11px] text-muted">Layout</label>
     <div class="flex gap-1.5">
       <!-- Width -->
@@ -147,6 +147,7 @@ function setAlignment(primary: LayoutAlign, counter: LayoutCounterAlign) {
         </button>
         <div
           v-if="widthSizingOpen"
+          data-test-id="layout-width-sizing-dropdown"
           class="absolute top-full left-0 right-0 z-10 min-w-40 rounded-md border border-border bg-panel p-1 shadow-lg"
         >
           <button
@@ -194,6 +195,7 @@ function setAlignment(primary: LayoutAlign, counter: LayoutCounterAlign) {
         </button>
         <div
           v-if="heightSizingOpen"
+          data-test-id="layout-height-sizing-dropdown"
           class="absolute top-full left-0 right-0 z-10 min-w-40 rounded-md border border-border bg-panel p-1 shadow-lg"
         >
           <button
@@ -233,6 +235,7 @@ function setAlignment(primary: LayoutAlign, counter: LayoutCounterAlign) {
       <button
         v-if="node.layoutMode === 'NONE'"
         class="cursor-pointer rounded border-none bg-transparent px-1 text-base leading-none text-muted hover:bg-hover hover:text-surface"
+        data-test-id="layout-add-auto"
         title="Add auto layout (Shift+A)"
         @click="store.setLayoutMode(node.id, 'VERTICAL')"
       >
@@ -241,6 +244,7 @@ function setAlignment(primary: LayoutAlign, counter: LayoutCounterAlign) {
       <button
         v-else
         class="cursor-pointer rounded border-none bg-transparent px-1 text-base leading-none text-muted hover:bg-hover hover:text-surface"
+        data-test-id="layout-remove-auto"
         title="Remove auto layout"
         @click="store.setLayoutMode(node.id, 'NONE')"
       >
@@ -258,6 +262,7 @@ function setAlignment(primary: LayoutAlign, counter: LayoutCounterAlign) {
               ? 'border-accent bg-accent text-white'
               : 'border-border bg-input text-muted hover:bg-hover hover:text-surface'
           "
+          data-test-id="layout-direction-vertical"
           title="Vertical layout"
           @click="store.setLayoutMode(node.id, 'VERTICAL')"
         >
@@ -274,6 +279,7 @@ function setAlignment(primary: LayoutAlign, counter: LayoutCounterAlign) {
               ? 'border-accent bg-accent text-white'
               : 'border-border bg-input text-muted hover:bg-hover hover:text-surface'
           "
+          data-test-id="layout-direction-horizontal"
           title="Horizontal layout"
           @click="store.setLayoutMode(node.id, 'HORIZONTAL')"
         >
@@ -290,6 +296,7 @@ function setAlignment(primary: LayoutAlign, counter: LayoutCounterAlign) {
               ? 'border-accent bg-accent text-white'
               : 'border-border bg-input text-muted hover:bg-hover hover:text-surface'
           "
+          data-test-id="layout-direction-wrap"
           title="Wrap"
           @click="updateProp('layoutWrap', node.layoutWrap === 'WRAP' ? 'NO_WRAP' : 'WRAP')"
         >
@@ -303,7 +310,10 @@ function setAlignment(primary: LayoutAlign, counter: LayoutCounterAlign) {
 
       <!-- Alignment grid + Gap -->
       <div class="mt-1.5 flex items-center gap-2">
-        <div class="grid grid-cols-3 gap-0.5 rounded border border-border bg-input p-1">
+        <div
+          data-test-id="layout-alignment-grid"
+          class="grid grid-cols-3 gap-0.5 rounded border border-border bg-input p-1"
+        >
           <button
             v-for="(a, i) in ALIGN_GRID"
             :key="i"
diff --git a/src/components/properties/PageSection.vue b/src/components/properties/PageSection.vue
index f9d434ff1..b78b08d8f 100644
--- a/src/components/properties/PageSection.vue
+++ b/src/components/properties/PageSection.vue
@@ -13,7 +13,7 @@ function updateColor(color: Color) {
 </script>
 
 <template>
-  <div class="border-b border-border px-3 py-2">
+  <div data-test-id="page-section" class="border-b border-border px-3 py-2">
     <label class="mb-1.5 block text-[11px] text-muted">Page</label>
     <ColorInput :color="store.state.pageColor" editable @update="updateColor" />
   </div>
diff --git a/src/components/properties/PositionSection.vue b/src/components/properties/PositionSection.vue
index 06dd08bca..23490d914 100644
--- a/src/components/properties/PositionSection.vue
+++ b/src/components/properties/PositionSection.vue
@@ -124,7 +124,7 @@ function rotate90() {
 </script>
 
 <template>
-  <div v-if="active" class="border-b border-border px-3 py-2">
+  <div v-if="active" data-test-id="position-section" class="border-b border-border px-3 py-2">
     <label class="mb-1.5 block text-[11px] text-muted">Position</label>
 
     <!-- Alignment buttons -->
@@ -132,6 +132,7 @@ function rotate90() {
       <div class="flex gap-0.5">
         <button
           class="flex size-7 cursor-pointer items-center justify-center rounded border border-border bg-input text-muted hover:bg-hover hover:text-surface"
+          data-test-id="position-align-left"
           title="Align left"
           @click="alignHorizontal('left')"
         >
@@ -139,6 +140,7 @@ function rotate90() {
         </button>
         <button
           class="flex size-7 cursor-pointer items-center justify-center rounded border border-border bg-input text-muted hover:bg-hover hover:text-surface"
+          data-test-id="position-align-center-h"
           title="Align center horizontally"
           @click="alignHorizontal('center')"
         >
@@ -146,6 +148,7 @@ function rotate90() {
         </button>
         <button
           class="flex size-7 cursor-pointer items-center justify-center rounded border border-border bg-input text-muted hover:bg-hover hover:text-surface"
+          data-test-id="position-align-right"
           title="Align right"
           @click="alignHorizontal('right')"
         >
@@ -155,6 +158,7 @@ function rotate90() {
       <div class="flex gap-0.5">
         <button
           class="flex size-7 cursor-pointer items-center justify-center rounded border border-border bg-input text-muted hover:bg-hover hover:text-surface"
+          data-test-id="position-align-top"
           title="Align top"
           @click="alignVertical('top')"
         >
@@ -162,6 +166,7 @@ function rotate90() {
         </button>
         <button
           class="flex size-7 cursor-pointer items-center justify-center rounded border border-border bg-input text-muted hover:bg-hover hover:text-surface"
+          data-test-id="position-align-center-v"
           title="Align center vertically"
           @click="alignVertical('center')"
         >
@@ -169,6 +174,7 @@ function rotate90() {
         </button>
         <button
           class="flex size-7 cursor-pointer items-center justify-center rounded border border-border bg-input text-muted hover:bg-hover hover:text-surface"
+          data-test-id="position-align-bottom"
           title="Align bottom"
           @click="alignVertical('bottom')"
         >
@@ -228,6 +234,7 @@ function rotate90() {
       </ScrubInput>
       <button
         class="flex size-7 shrink-0 cursor-pointer items-center justify-center rounded border border-border bg-input text-muted hover:bg-hover hover:text-surface"
+        data-test-id="position-flip-horizontal"
         title="Flip horizontal"
         @click="flipHorizontal"
       >
@@ -235,6 +242,7 @@ function rotate90() {
       </button>
       <button
         class="flex size-7 shrink-0 cursor-pointer items-center justify-center rounded border border-border bg-input text-muted hover:bg-hover hover:text-surface"
+        data-test-id="position-flip-vertical"
         title="Flip vertical"
         @click="flipVertical"
       >
@@ -242,6 +250,7 @@ function rotate90() {
       </button>
       <button
         class="flex size-7 shrink-0 cursor-pointer items-center justify-center rounded border border-border bg-input text-muted hover:bg-hover hover:text-surface"
+        data-test-id="position-rotate-90"
         title="Rotate 90°"
         @click="rotate90"
       >
diff --git a/src/components/properties/StrokeSection.vue b/src/components/properties/StrokeSection.vue
index 83a3c362a..11db52091 100644
--- a/src/components/properties/StrokeSection.vue
+++ b/src/components/properties/StrokeSection.vue
@@ -231,18 +231,16 @@ const borderWeights = computed(() => {
 </script>
 
 <template>
-  <div v-if="active" class="border-b border-border px-3 py-2">
-    <!-- Header: label + add button -->
+  <div v-if="active" data-test-id="stroke-section" class="border-b border-border px-3 py-2">
     <div class="flex items-center justify-between">
       <label class="mb-1 block text-[11px] text-muted">Stroke</label>
-      <div class="flex items-center gap-0.5">
-        <button
-          class="flex size-5 cursor-pointer items-center justify-center rounded border-none bg-transparent text-sm leading-none text-muted hover:bg-hover hover:text-surface"
-          @click="add"
-        >
-          +
-        </button>
-      </div>
+      <button
+        data-test-id="stroke-section-add"
+        class="flex size-5 cursor-pointer items-center justify-center rounded border-none bg-transparent text-sm leading-none text-muted hover:bg-hover hover:text-surface"
+        @click="add"
+      >
+        +
+      </button>
     </div>
 
     <p v-if="strokesAreMixed" class="text-[11px] text-muted">Click + to replace mixed strokes</p>
@@ -251,6 +249,8 @@ const borderWeights = computed(() => {
     <div
       v-for="(stroke, i) in strokesAreMixed ? [] : (activeNode?.strokes ?? [])"
       :key="i"
+      data-test-id="stroke-item"
+      :data-test-index="i"
       class="group flex items-center gap-1.5 py-0.5"
     >
       <ColorInput
diff --git a/src/components/properties/TypographySection.vue b/src/components/properties/TypographySection.vue
index f10e381dd..0e9c1a5aa 100644
--- a/src/components/properties/TypographySection.vue
+++ b/src/components/properties/TypographySection.vue
@@ -73,13 +73,14 @@ onMounted(async () => {
 </script>
 
 <template>
-  <div v-if="node" class="border-b border-border px-3 py-2">
+  <div v-if="node" data-test-id="typography-section" class="border-b border-border px-3 py-2">
     <label class="mb-1.5 block text-[11px] text-muted">Typography</label>
 
     <div class="mb-1.5 flex items-center gap-1.5">
       <FontPicker class="min-w-0 flex-1" :model-value="node.fontFamily" @select="selectFamily" />
       <icon-lucide-alert-triangle
         v-if="hasMissingFonts"
+        data-test-id="typography-missing-font"
         class="size-3.5 shrink-0 text-amber-400"
         :title="
           'Missing font' + (missingFonts.length > 1 ? 's' : '') + ': ' + missingFonts.join(', ')
diff --git a/src/components/properties/VariablesSection.vue b/src/components/properties/VariablesSection.vue
index 12a828146..94059382e 100644
--- a/src/components/properties/VariablesSection.vue
+++ b/src/components/properties/VariablesSection.vue
@@ -18,10 +18,11 @@ const variableCount = computed(() => {
 </script>
 
 <template>
-  <div class="border-b border-border px-3 py-2">
+  <div data-test-id="variables-section" class="border-b border-border px-3 py-2">
     <div class="flex items-center justify-between">
       <label class="text-[11px] font-medium text-surface">Variables</label>
       <button
+        data-test-id="variables-section-open"
         class="flex size-5 cursor-pointer items-center justify-center rounded border-none bg-transparent text-muted hover:bg-hover hover:text-surface"
         title="Open variables"
         @click="emit('openDialog')"
diff --git a/src/views/EditorView.vue b/src/views/EditorView.vue
index 556601526..6d1ba9da0 100644
--- a/src/views/EditorView.vue
+++ b/src/views/EditorView.vue
@@ -66,7 +66,7 @@ function onDisconnect() {
 </script>
 
 <template>
-  <div class="flex h-screen w-screen flex-col">
+  <div data-test-id="editor-root" class="flex h-screen w-screen flex-col">
     <SafariBanner />
     <TabBar />
     <SplitterGroup
@@ -122,8 +122,11 @@ function onDisconnect() {
           class="absolute left-7 top-7 z-10 flex items-center gap-2 rounded-lg border border-border bg-panel px-2 py-1 shadow-sm"
         >
           <img src="/favicon-32.png" class="size-4" alt="OpenPencil" />
-          <span class="text-xs text-surface">{{ store.state.documentName }}</span>
+          <span data-test-id="editor-document-name" class="text-xs text-surface">{{
+            store.state.documentName
+          }}</span>
           <button
+            data-test-id="editor-show-ui"
             class="ml-1 flex size-6 cursor-pointer items-center justify-center rounded text-muted transition-colors hover:bg-hover hover:text-surface"
             title="Show UI (⌘\)"
             @click="store.state.showUI = true"