diff --git a/frontend/src/App.vue b/frontend/src/App.vue
index 64d898f..52affe7 100644
--- a/frontend/src/App.vue
+++ b/frontend/src/App.vue
@@ -1,8 +1,30 @@
 <template>
-  <div class="h-screen flex items-center justify-center">
-    <div class="text-center">
-      <h1 class="text-3xl font-bold text-[#58a6ff]">WRAITH</h1>
-      <p class="text-[#8b949e] mt-2">Desktop shell loading...</p>
+  <div class="h-screen w-screen bg-[var(--wraith-bg-primary)]">
+    <!-- Loading state -->
+    <div v-if="appStore.isLoading" class="h-full flex items-center justify-center">
+      <div class="text-center">
+        <h1 class="text-3xl font-bold text-[var(--wraith-accent-blue)]">WRAITH</h1>
+        <p class="text-[var(--wraith-text-secondary)] mt-2">Loading...</p>
+      </div>
     </div>
+
+    <!-- Unlock screen -->
+    <UnlockLayout v-else-if="!appStore.isUnlocked" />
+
+    <!-- Main application -->
+    <MainLayout v-else />
   </div>
 </template>
+
+<script setup lang="ts">
+import { onMounted } from "vue";
+import { useAppStore } from "@/stores/app.store";
+import UnlockLayout from "@/layouts/UnlockLayout.vue";
+import MainLayout from "@/layouts/MainLayout.vue";
+
+const appStore = useAppStore();
+
+onMounted(() => {
+  appStore.checkFirstRun();
+});
+</script>
diff --git a/frontend/src/env.d.ts b/frontend/src/env.d.ts
new file mode 100644
index 0000000..cd39087
--- /dev/null
+++ b/frontend/src/env.d.ts
@@ -0,0 +1,7 @@
+/// <reference types="vite/client" />
+
+declare module "*.vue" {
+  import type { DefineComponent } from "vue";
+  const component: DefineComponent<object, object, unknown>;
+  export default component;
+}
diff --git a/frontend/src/layouts/UnlockLayout.vue b/frontend/src/layouts/UnlockLayout.vue
new file mode 100644
index 0000000..8931322
--- /dev/null
+++ b/frontend/src/layouts/UnlockLayout.vue
@@ -0,0 +1,122 @@
+<template>
+  <div class="h-screen w-screen flex items-center justify-center bg-[var(--wraith-bg-primary)]">
+    <div class="w-full max-w-sm px-6">
+      <!-- Branding -->
+      <div class="text-center mb-8">
+        <h1 class="text-4xl font-bold tracking-widest text-[var(--wraith-accent-blue)]">
+          WRAITH
+        </h1>
+        <p class="text-[var(--wraith-text-secondary)] mt-2 text-sm">
+          {{ appStore.isFirstRun ? "Create a master password" : "Enter your master password" }}
+        </p>
+      </div>
+
+      <!-- Card -->
+      <form
+        class="bg-[var(--wraith-bg-secondary)] border border-[var(--wraith-border)] rounded-lg p-6 space-y-4"
+        @submit.prevent="handleSubmit"
+      >
+        <!-- Error -->
+        <div
+          v-if="appStore.error"
+          class="text-sm text-[var(--wraith-accent-red)] bg-[var(--wraith-accent-red)]/10 border border-[var(--wraith-accent-red)]/20 rounded px-3 py-2"
+        >
+          {{ appStore.error }}
+        </div>
+
+        <!-- Password -->
+        <div>
+          <label class="block text-xs text-[var(--wraith-text-secondary)] mb-1.5">
+            Master Password
+          </label>
+          <input
+            ref="passwordInput"
+            v-model="password"
+            type="password"
+            autocomplete="current-password"
+            placeholder="Enter password..."
+            class="w-full px-3 py-2 text-sm rounded bg-[var(--wraith-bg-tertiary)] border border-[var(--wraith-border)] text-[var(--wraith-text-primary)] placeholder-[var(--wraith-text-muted)] outline-none focus:border-[var(--wraith-accent-blue)] transition-colors"
+            @input="appStore.clearError()"
+          />
+        </div>
+
+        <!-- Confirm password (first run only) -->
+        <div v-if="appStore.isFirstRun">
+          <label class="block text-xs text-[var(--wraith-text-secondary)] mb-1.5">
+            Confirm Password
+          </label>
+          <input
+            v-model="confirmPassword"
+            type="password"
+            autocomplete="new-password"
+            placeholder="Confirm password..."
+            class="w-full px-3 py-2 text-sm rounded bg-[var(--wraith-bg-tertiary)] border border-[var(--wraith-border)] text-[var(--wraith-text-primary)] placeholder-[var(--wraith-text-muted)] outline-none focus:border-[var(--wraith-accent-blue)] transition-colors"
+            @input="appStore.clearError()"
+          />
+        </div>
+
+        <!-- Submit -->
+        <button
+          type="submit"
+          :disabled="submitting"
+          class="w-full py-2 text-sm font-medium rounded bg-[var(--wraith-accent-blue)] text-white hover:opacity-90 disabled:opacity-50 transition-opacity cursor-pointer disabled:cursor-not-allowed"
+        >
+          <span v-if="submitting">{{ appStore.isFirstRun ? "Creating..." : "Unlocking..." }}</span>
+          <span v-else>{{ appStore.isFirstRun ? "Create Vault" : "Unlock" }}</span>
+        </button>
+      </form>
+
+      <!-- Version -->
+      <p class="text-center text-xs text-[var(--wraith-text-muted)] mt-4">
+        v1.0.0-alpha
+      </p>
+    </div>
+  </div>
+</template>
+
+<script setup lang="ts">
+import { ref, onMounted } from "vue";
+import { useAppStore } from "@/stores/app.store";
+
+const appStore = useAppStore();
+
+const password = ref("");
+const confirmPassword = ref("");
+const submitting = ref(false);
+const passwordInput = ref<HTMLInputElement | null>(null);
+
+onMounted(() => {
+  passwordInput.value?.focus();
+});
+
+async function handleSubmit(): Promise<void> {
+  if (!password.value) {
+    appStore.error = "Password is required";
+    return;
+  }
+
+  if (appStore.isFirstRun) {
+    if (password.value.length < 8) {
+      appStore.error = "Password must be at least 8 characters";
+      return;
+    }
+    if (password.value !== confirmPassword.value) {
+      appStore.error = "Passwords do not match";
+      return;
+    }
+  }
+
+  submitting.value = true;
+  try {
+    if (appStore.isFirstRun) {
+      await appStore.createVault(password.value);
+    } else {
+      await appStore.unlock(password.value);
+    }
+  } catch {
+    // Error is set in the store
+  } finally {
+    submitting.value = false;
+  }
+}
+</script>
diff --git a/frontend/src/stores/app.store.ts b/frontend/src/stores/app.store.ts
new file mode 100644
index 0000000..6cc3d37
--- /dev/null
+++ b/frontend/src/stores/app.store.ts
@@ -0,0 +1,77 @@
+import { defineStore } from "pinia";
+import { ref } from "vue";
+
+/**
+ * Wraith application store.
+ * Manages unlock state, first-run detection, and vault operations.
+ *
+ * Once Wails v3 bindings are generated, the mock calls below will be
+ * replaced with actual WraithApp.IsFirstRun(), CreateVault(), Unlock(), etc.
+ */
+export const useAppStore = defineStore("app", () => {
+  const isUnlocked = ref(false);
+  const isFirstRun = ref(true);
+  const isLoading = ref(true);
+  const error = ref<string | null>(null);
+
+  /** Check whether the vault has been created before. */
+  async function checkFirstRun(): Promise<void> {
+    try {
+      // TODO: replace with Wails binding — WraithApp.IsFirstRun()
+      isFirstRun.value = true;
+    } catch {
+      isFirstRun.value = true;
+    } finally {
+      isLoading.value = false;
+    }
+  }
+
+  /** Create a new vault with the given master password. */
+  async function createVault(password: string): Promise<void> {
+    error.value = null;
+    try {
+      // TODO: replace with Wails binding — WraithApp.CreateVault(password)
+      void password;
+      isFirstRun.value = false;
+      isUnlocked.value = true;
+    } catch (e) {
+      error.value = e instanceof Error ? e.message : "Failed to create vault";
+      throw e;
+    }
+  }
+
+  /** Unlock an existing vault with the master password. */
+  async function unlock(password: string): Promise<void> {
+    error.value = null;
+    try {
+      // TODO: replace with Wails binding — WraithApp.Unlock(password)
+      void password;
+      isUnlocked.value = true;
+    } catch (e) {
+      error.value = e instanceof Error ? e.message : "Invalid master password";
+      throw e;
+    }
+  }
+
+  /** Lock the vault (return to unlock screen). */
+  function lock(): void {
+    isUnlocked.value = false;
+  }
+
+  /** Clear the current error message. */
+  function clearError(): void {
+    error.value = null;
+  }
+
+  return {
+    isUnlocked,
+    isFirstRun,
+    isLoading,
+    error,
+    checkFirstRun,
+    createVault,
+    unlock,
+    lock,
+    clearError,
+  };
+});
diff --git a/frontend/vite.config.ts b/frontend/vite.config.ts
index 111aca4..2896b7c 100644
--- a/frontend/vite.config.ts
+++ b/frontend/vite.config.ts
@@ -1,7 +1,13 @@
 import { defineConfig } from "vite";
 import vue from "@vitejs/plugin-vue";
 import tailwindcss from "@tailwindcss/vite";
+import { resolve } from "path";
 
 export default defineConfig({
   plugins: [vue(), tailwindcss()],
+  resolve: {
+    alias: {
+      "@": resolve(__dirname, "src"),
+    },
+  },
 });