diff --git a/CLAUDE.md b/CLAUDE.md
index 17ac4af..f3078e2 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -8,3 +8,6 @@ As an example, we have as high of a bar as a product team like Linear, which out
 
 ### Package Manager
 - Use **yarn** (not npm) for all dependency management
+
+### Design system
+Whenever possible, we should use the design system components. If we need to add a new component from the available ones in [shadcn](https://ui.shadcn.com/docs/components), we should add it to the design system (using `shadcn add _`) and use it in the app.
diff --git a/js/package.json b/js/package.json
index 98304f1..260732d 100644
--- a/js/package.json
+++ b/js/package.json
@@ -54,6 +54,7 @@
     "shadcn": "^3.8.5",
     "tailwind-merge": "^3.5.0",
     "tailwindcss": "^4.2.0",
-    "tw-animate-css": "^1.4.0"
+    "tw-animate-css": "^1.4.0",
+    "zustand": "^5.0.11"
   }
 }
diff --git a/js/src/App.tsx b/js/src/App.tsx
index 7d8c3c2..c495695 100644
--- a/js/src/App.tsx
+++ b/js/src/App.tsx
@@ -1,27 +1,29 @@
-import { useEffect, useState } from 'react';
-import { Button } from '@/components/ui/button';
-import { P, H1 } from '@/components/ui/typography';
+import { useEffect } from "react";
+import { useAuthStore } from "@/stores/auth-store";
+import { LoginPage } from "@/features/auth/login-page";
+import { HomePage } from "@/pages/home-page";
 
 const App = () => {
-  useEffect(
-    () => {
-      console.log('loaded');
-    },
-    []
-  );
-  const [state, updateState] = useState(1);
+  const status = useAuthStore((s) => s.status);
+  const restoreSession = useAuthStore((s) => s.restoreSession);
 
-  return (
-    <div>
-      <H1>Hello World!</H1>
-      <P>Welcome to your Electron application.</P>
-      <P>What is the purpose of this app</P>
-      <Button onClick={() => {
-        console.log(state);
-        updateState(state + 1);
-      }}>Click me</Button>
-    </div>
-  );
+  useEffect(() => {
+    restoreSession();
+  }, [restoreSession]);
+
+  if (status === "idle" || status === "restoring") {
+    return (
+      <div className="flex min-h-screen items-center justify-center">
+        <p className="text-muted-foreground text-sm">Loading...</p>
+      </div>
+    );
+  }
+
+  if (status === "authenticated") {
+    return <HomePage />;
+  }
+
+  return <LoginPage />;
 };
 
 export default App;
diff --git a/js/src/api/client.ts b/js/src/api/client.ts
new file mode 100644
index 0000000..d294bd1
--- /dev/null
+++ b/js/src/api/client.ts
@@ -0,0 +1,95 @@
+import { useSessionStore } from "@/stores/session-store";
+import type {
+  Human,
+  RequestCodeRequest,
+  SignInRequest,
+  SignInResponse,
+  StartupResponse,
+} from "./types";
+
+export class ApiError extends Error {
+  constructor(
+    public status: number,
+    message: string,
+  ) {
+    super(message);
+    this.name = "ApiError";
+  }
+}
+
+interface ApiClientConfig {
+  baseUrl: string;
+  getToken: () => string | null;
+  onUnauthorized: () => void;
+}
+
+class ApiClient {
+  private config: ApiClientConfig;
+
+  constructor(config: ApiClientConfig) {
+    this.config = config;
+  }
+
+  private async request<T>(
+    method: string,
+    path: string,
+    body?: unknown,
+  ): Promise<T> {
+    const headers: Record<string, string> = {
+      "Content-Type": "application/json",
+    };
+
+    const token = this.config.getToken();
+    if (token) {
+      headers["Authorization"] = `Bearer ${token}`;
+    }
+
+    const response = await fetch(`${this.config.baseUrl}${path}`, {
+      method,
+      headers,
+      body: body ? JSON.stringify(body) : undefined,
+    });
+
+    if (response.status === 401) {
+      this.config.onUnauthorized();
+      throw new ApiError(401, "Unauthorized");
+    }
+
+    if (!response.ok) {
+      const text = await response.text().catch(() => "Unknown error");
+      throw new ApiError(response.status, text);
+    }
+
+    if (response.status === 204) {
+      return undefined as T;
+    }
+
+    return response.json() as Promise<T>;
+  }
+
+  async requestCode(data: RequestCodeRequest): Promise<void> {
+    await this.request<void>("POST", "/auth/request-code", data);
+  }
+
+  async signIn(data: SignInRequest): Promise<SignInResponse> {
+    return this.request<SignInResponse>("POST", "/auth/sign-in", data);
+  }
+
+  async me(): Promise<Human> {
+    return this.request<Human>("GET", "/auth/me");
+  }
+
+  async signOut(): Promise<void> {
+    await this.request<void>("POST", "/auth/sign-out");
+  }
+
+  async startup(): Promise<StartupResponse> {
+    return this.request<StartupResponse>("GET", "/startup");
+  }
+}
+
+export const apiClient = new ApiClient({
+  baseUrl: "https://orion.dev.flowy.live",
+  getToken: () => useSessionStore.getState().token,
+  onUnauthorized: () => useSessionStore.getState().clearToken(),
+});
diff --git a/js/src/api/types.ts b/js/src/api/types.ts
new file mode 100644
index 0000000..12f03ab
--- /dev/null
+++ b/js/src/api/types.ts
@@ -0,0 +1,25 @@
+export interface Human {
+  id: string;
+  email: string;
+  email_prefix: string;
+  created_at: string;
+  updated_at: string;
+}
+
+export interface RequestCodeRequest {
+  email: string;
+}
+
+export interface SignInRequest {
+  email: string;
+  code: string;
+}
+
+export interface SignInResponse {
+  human: Human;
+  token: string;
+}
+
+export interface StartupResponse {
+  networks: unknown[];
+}
diff --git a/js/src/components/ui/input.tsx b/js/src/components/ui/input.tsx
new file mode 100644
index 0000000..d591c47
--- /dev/null
+++ b/js/src/components/ui/input.tsx
@@ -0,0 +1,19 @@
+import * as React from "react"
+
+import { cn } from "@/lib/utils"
+
+function Input({ className, type, ...props }: React.ComponentProps<"input">) {
+  return (
+    <input
+      type={type}
+      data-slot="input"
+      className={cn(
+        "dark:bg-input/30 border-input focus-visible:border-ring focus-visible:ring-ring/50 aria-invalid:ring-destructive/20 dark:aria-invalid:ring-destructive/40 aria-invalid:border-destructive dark:aria-invalid:border-destructive/50 disabled:bg-input/50 dark:disabled:bg-input/80 h-8 rounded-lg border bg-transparent px-2.5 py-1 text-base transition-colors file:h-6 file:text-sm file:font-medium focus-visible:ring-3 aria-invalid:ring-3 md:text-sm file:text-foreground placeholder:text-muted-foreground w-full min-w-0 outline-none file:inline-flex file:border-0 file:bg-transparent disabled:pointer-events-none disabled:cursor-not-allowed disabled:opacity-50",
+        className
+      )}
+      {...props}
+    />
+  )
+}
+
+export { Input }
diff --git a/js/src/components/ui/label.tsx b/js/src/components/ui/label.tsx
new file mode 100644
index 0000000..33dc071
--- /dev/null
+++ b/js/src/components/ui/label.tsx
@@ -0,0 +1,22 @@
+import * as React from "react"
+import { Label as LabelPrimitive } from "radix-ui"
+
+import { cn } from "@/lib/utils"
+
+function Label({
+  className,
+  ...props
+}: React.ComponentProps<typeof LabelPrimitive.Root>) {
+  return (
+    <LabelPrimitive.Root
+      data-slot="label"
+      className={cn(
+        "gap-2 text-sm leading-none font-medium group-data-[disabled=true]:opacity-50 peer-disabled:opacity-50 flex items-center select-none group-data-[disabled=true]:pointer-events-none peer-disabled:cursor-not-allowed",
+        className
+      )}
+      {...props}
+    />
+  )
+}
+
+export { Label }
diff --git a/js/src/features/auth/code-step.tsx b/js/src/features/auth/code-step.tsx
new file mode 100644
index 0000000..087ec1b
--- /dev/null
+++ b/js/src/features/auth/code-step.tsx
@@ -0,0 +1,69 @@
+import { type FormEvent, useState } from "react";
+import { Button } from "@/components/ui/button";
+import { Input } from "@/components/ui/input";
+import { Label } from "@/components/ui/label";
+import { H3, Muted } from "@/components/ui/typography";
+import { useAuthStore } from "@/stores/auth-store";
+
+interface CodeStepProps {
+  email: string;
+  onBack: () => void;
+}
+
+export function CodeStep({ email, onBack }: CodeStepProps) {
+  const [code, setCode] = useState("");
+  const isSigningIn = useAuthStore((s) => s.isSigningIn);
+  const error = useAuthStore((s) => s.error);
+  const signIn = useAuthStore((s) => s.signIn);
+  const clearError = useAuthStore((s) => s.clearError);
+
+  const handleSubmit = async (e: FormEvent) => {
+    e.preventDefault();
+    try {
+      await signIn(email, code);
+    } catch {
+      // Error is set in the store
+    }
+  };
+
+  return (
+    <form onSubmit={handleSubmit} className="flex flex-col gap-4">
+      <div className="flex flex-col gap-2">
+        <H3>Check your email</H3>
+        <Muted>
+          We sent a code to <strong className="text-foreground">{email}</strong>.
+        </Muted>
+      </div>
+
+      <div className="flex flex-col gap-1.5">
+        <Label htmlFor="code">Code</Label>
+        <Input
+          id="code"
+          type="text"
+          inputMode="numeric"
+          placeholder="Enter code"
+          value={code}
+          onChange={(e) => {
+            setCode(e.target.value);
+            if (error) clearError();
+          }}
+          required
+          autoFocus
+        />
+      </div>
+
+      {error && (
+        <p className="text-sm text-destructive">{error}</p>
+      )}
+
+      <div className="flex flex-col gap-2">
+        <Button type="submit" disabled={isSigningIn || !code}>
+          {isSigningIn ? "Signing in..." : "Sign in"}
+        </Button>
+        <Button type="button" variant="ghost" onClick={onBack}>
+          Back
+        </Button>
+      </div>
+    </form>
+  );
+}
diff --git a/js/src/features/auth/email-step.tsx b/js/src/features/auth/email-step.tsx
new file mode 100644
index 0000000..9008cb7
--- /dev/null
+++ b/js/src/features/auth/email-step.tsx
@@ -0,0 +1,61 @@
+import { type FormEvent, useState } from "react";
+import { Button } from "@/components/ui/button";
+import { Input } from "@/components/ui/input";
+import { Label } from "@/components/ui/label";
+import { H3, Muted } from "@/components/ui/typography";
+import { useAuthStore } from "@/stores/auth-store";
+
+interface EmailStepProps {
+  onCodeSent: (email: string) => void;
+}
+
+export function EmailStep({ onCodeSent }: EmailStepProps) {
+  const [email, setEmail] = useState("");
+  const isRequestingCode = useAuthStore((s) => s.isRequestingCode);
+  const error = useAuthStore((s) => s.error);
+  const requestCode = useAuthStore((s) => s.requestCode);
+  const clearError = useAuthStore((s) => s.clearError);
+
+  const handleSubmit = async (e: FormEvent) => {
+    e.preventDefault();
+    try {
+      await requestCode(email);
+      onCodeSent(email);
+    } catch {
+      // Error is set in the store
+    }
+  };
+
+  return (
+    <form onSubmit={handleSubmit} className="flex flex-col gap-4">
+      <div className="flex flex-col gap-2">
+        <H3>Sign in</H3>
+        <Muted>Enter your email to receive a sign-in code.</Muted>
+      </div>
+
+      <div className="flex flex-col gap-1.5">
+        <Label htmlFor="email">Email</Label>
+        <Input
+          id="email"
+          type="email"
+          placeholder="you@example.com"
+          value={email}
+          onChange={(e) => {
+            setEmail(e.target.value);
+            if (error) clearError();
+          }}
+          required
+          autoFocus
+        />
+      </div>
+
+      {error && (
+        <p className="text-sm text-destructive">{error}</p>
+      )}
+
+      <Button type="submit" disabled={isRequestingCode || !email}>
+        {isRequestingCode ? "Sending..." : "Continue"}
+      </Button>
+    </form>
+  );
+}
diff --git a/js/src/features/auth/login-page.tsx b/js/src/features/auth/login-page.tsx
new file mode 100644
index 0000000..c4b2686
--- /dev/null
+++ b/js/src/features/auth/login-page.tsx
@@ -0,0 +1,30 @@
+import { useState } from "react";
+import { EmailStep } from "./email-step";
+import { CodeStep } from "./code-step";
+
+type Step = "email" | "code";
+
+export function LoginPage() {
+  const [step, setStep] = useState<Step>("email");
+  const [email, setEmail] = useState("");
+
+  return (
+    <div className="flex min-h-screen items-center justify-center p-4">
+      <div className="w-full max-w-sm">
+        {step === "email" ? (
+          <EmailStep
+            onCodeSent={(submittedEmail) => {
+              setEmail(submittedEmail);
+              setStep("code");
+            }}
+          />
+        ) : (
+          <CodeStep
+            email={email}
+            onBack={() => setStep("email")}
+          />
+        )}
+      </div>
+    </div>
+  );
+}
diff --git a/js/src/main.ts b/js/src/main.ts
index f4f001e..8ca5c0f 100644
--- a/js/src/main.ts
+++ b/js/src/main.ts
@@ -1,4 +1,4 @@
-import { app, BrowserWindow } from 'electron';
+import { app, BrowserWindow, session } from 'electron';
 import path from 'node:path';
 import started from 'electron-squirrel-startup';
 
@@ -33,7 +33,28 @@ const createWindow = () => {
 // This method will be called when Electron has finished
 // initialization and is ready to create browser windows.
 // Some APIs can only be used after this event occurs.
-app.on('ready', createWindow);
+app.on('ready', () => {
+  // Allow CORS for API requests from the renderer process.
+  // The server doesn't handle OPTIONS preflight, so we intercept at the
+  // Electron network layer: inject CORS headers and return 200 for preflight.
+  session.defaultSession.webRequest.onHeadersReceived(
+    { urls: ['https://orion.dev.flowy.live/*'] },
+    (details, callback) => {
+      const headers = { ...details.responseHeaders };
+      headers['access-control-allow-origin'] = ['*'];
+      headers['access-control-allow-headers'] = ['Content-Type', 'Authorization'];
+      headers['access-control-allow-methods'] = ['GET', 'POST', 'PUT', 'DELETE', 'OPTIONS'];
+
+      if (details.method === 'OPTIONS') {
+        callback({ responseHeaders: headers, statusLine: 'HTTP/1.1 200 OK' });
+      } else {
+        callback({ responseHeaders: headers });
+      }
+    },
+  );
+
+  createWindow();
+});
 
 // Quit when all windows are closed, except on macOS. There, it's common
 // for applications and their menu bar to stay active until the user quits
diff --git a/js/src/pages/home-page.tsx b/js/src/pages/home-page.tsx
new file mode 100644
index 0000000..2e6d9a7
--- /dev/null
+++ b/js/src/pages/home-page.tsx
@@ -0,0 +1,26 @@
+import { useEffect } from "react";
+import { Button } from "@/components/ui/button";
+import { H1, Muted } from "@/components/ui/typography";
+import { useAuthStore } from "@/stores/auth-store";
+import { useAppStore } from "@/stores/app-store";
+
+export function HomePage() {
+  const user = useAuthStore((s) => s.user);
+  const isSigningOut = useAuthStore((s) => s.isSigningOut);
+  const signOut = useAuthStore((s) => s.signOut);
+  const fetchStartup = useAppStore((s) => s.fetchStartup);
+
+  useEffect(() => {
+    fetchStartup();
+  }, [fetchStartup]);
+
+  return (
+    <div className="flex min-h-screen flex-col items-center justify-center gap-4 p-4">
+      <H1>Welcome, {user?.email_prefix}</H1>
+      <Muted>{user?.email}</Muted>
+      <Button variant="outline" onClick={signOut} disabled={isSigningOut}>
+        {isSigningOut ? "Signing out..." : "Sign out"}
+      </Button>
+    </div>
+  );
+}
diff --git a/js/src/stores/app-store.ts b/js/src/stores/app-store.ts
new file mode 100644
index 0000000..822cf87
--- /dev/null
+++ b/js/src/stores/app-store.ts
@@ -0,0 +1,24 @@
+import { create } from "zustand";
+import { apiClient } from "@/api/client";
+import type { StartupResponse } from "@/api/types";
+
+interface AppState {
+  startupData: StartupResponse | null;
+  isLoading: boolean;
+  fetchStartup: () => Promise<void>;
+}
+
+export const useAppStore = create<AppState>((set) => ({
+  startupData: null,
+  isLoading: false,
+
+  fetchStartup: async () => {
+    set({ isLoading: true });
+    try {
+      const data = await apiClient.startup();
+      set({ startupData: data });
+    } finally {
+      set({ isLoading: false });
+    }
+  },
+}));
diff --git a/js/src/stores/auth-store.ts b/js/src/stores/auth-store.ts
new file mode 100644
index 0000000..252b5bd
--- /dev/null
+++ b/js/src/stores/auth-store.ts
@@ -0,0 +1,109 @@
+import { create } from "zustand";
+import { apiClient, ApiError } from "@/api/client";
+import type { Human } from "@/api/types";
+import { useSessionStore } from "./session-store";
+
+type AuthStatus = "idle" | "restoring" | "unauthenticated" | "authenticated";
+
+interface AuthState {
+  status: AuthStatus;
+  user: Human | null;
+  isRequestingCode: boolean;
+  isSigningIn: boolean;
+  isSigningOut: boolean;
+  error: string | null;
+  restoreSession: () => Promise<void>;
+  requestCode: (email: string) => Promise<void>;
+  signIn: (email: string, code: string) => Promise<void>;
+  signOut: () => Promise<void>;
+  clearError: () => void;
+}
+
+export const useAuthStore = create<AuthState>((set) => ({
+  status: "idle",
+  user: null,
+  isRequestingCode: false,
+  isSigningIn: false,
+  isSigningOut: false,
+  error: null,
+
+  restoreSession: async () => {
+    const token = useSessionStore.getState().token;
+    if (!token) {
+      set({ status: "unauthenticated" });
+      return;
+    }
+
+    set({ status: "restoring" });
+    try {
+      const user = await apiClient.me();
+      set({ status: "authenticated", user });
+    } catch {
+      useSessionStore.getState().clearToken();
+      set({ status: "unauthenticated", user: null });
+    }
+  },
+
+  requestCode: async (email: string) => {
+    set({ isRequestingCode: true, error: null });
+    try {
+      await apiClient.requestCode({ email });
+    } catch (e) {
+      const message =
+        e instanceof ApiError ? e.message : "Failed to send code";
+      set({ error: message });
+      throw e;
+    } finally {
+      set({ isRequestingCode: false });
+    }
+  },
+
+  signIn: async (email: string, code: string) => {
+    set({ isSigningIn: true, error: null });
+    try {
+      const { human, token } = await apiClient.signIn({ email, code });
+      useSessionStore.getState().setToken(token);
+      set({ status: "authenticated", user: human });
+    } catch (e) {
+      const message =
+        e instanceof ApiError ? e.message : "Failed to sign in";
+      set({ error: message });
+      throw e;
+    } finally {
+      set({ isSigningIn: false });
+    }
+  },
+
+  signOut: async () => {
+    set({ isSigningOut: true });
+    try {
+      await apiClient.signOut();
+    } catch {
+      // Best-effort — sign out locally regardless
+    } finally {
+      useSessionStore.getState().clearToken();
+      set({
+        status: "unauthenticated",
+        user: null,
+        isSigningOut: false,
+        error: null,
+      });
+    }
+  },
+
+  clearError: () => set({ error: null }),
+}));
+
+// React to token being cleared externally (e.g. 401 from API client)
+useSessionStore.subscribe((state, prevState) => {
+  if (prevState.token && !state.token) {
+    const authState = useAuthStore.getState();
+    if (authState.status === "authenticated") {
+      useAuthStore.setState({
+        status: "unauthenticated",
+        user: null,
+        error: null,
+      });
+    }
+  }
+});
diff --git a/js/src/stores/session-store.ts b/js/src/stores/session-store.ts
new file mode 100644
index 0000000..b00e154
--- /dev/null
+++ b/js/src/stores/session-store.ts
@@ -0,0 +1,23 @@
+import { create } from "zustand";
+
+const AUTH_TOKEN_KEY = "auth_token";
+
+interface SessionState {
+  token: string | null;
+  setToken: (token: string) => void;
+  clearToken: () => void;
+}
+
+export const useSessionStore = create<SessionState>((set) => ({
+  token: localStorage.getItem(AUTH_TOKEN_KEY),
+
+  setToken: (token: string) => {
+    localStorage.setItem(AUTH_TOKEN_KEY, token);
+    set({ token });
+  },
+
+  clearToken: () => {
+    localStorage.removeItem(AUTH_TOKEN_KEY);
+    set({ token: null });
+  },
+}));
diff --git a/js/yarn.lock b/js/yarn.lock
index d30332a..4da0b37 100644
--- a/js/yarn.lock
+++ b/js/yarn.lock
@@ -8003,3 +8003,8 @@ zod@^3.24.1:
   version "4.3.6"
   resolved "https://registry.yarnpkg.com/zod/-/zod-4.3.6.tgz#89c56e0aa7d2b05107d894412227087885ab112a"
   integrity sha512-rftlrkhHZOcjDwkGlnUtZZkvaPHCsDATp4pGpuOOMDaTdDDXF91wuVDJoWoPsKX/3YPQ5fHuF3STjcYyKr+Qhg==
+
+zustand@^5.0.11:
+  version "5.0.11"
+  resolved "https://registry.yarnpkg.com/zustand/-/zustand-5.0.11.tgz#99f912e590de1ca9ce6c6d1cab6cdb1f034ab494"
+  integrity sha512-fdZY+dk7zn/vbWNCYmzZULHRrss0jx5pPFiOuMZ/5HJN6Yv3u+1Wswy/4MpZEkEGhtNH+pwxZB8OKgUBPzYAGg==