diff --git a/src/app/login/page.tsx b/src/app/login/page.tsx
index eef6e31..43aa54b 100644
--- a/src/app/login/page.tsx
+++ b/src/app/login/page.tsx
@@ -1,6 +1,41 @@
+"use client";
+
 import Link from "next/link";
+import { FormEvent, useEffect, useState } from "react";
+import { useRouter } from "next/navigation";
+import { isAuthenticated, loginUser, seedDemoUser } from "../../lib/auth";
 
 export default function Login() {
+  const router = useRouter();
+  const [login, setLogin] = useState("");
+  const [password, setPassword] = useState("");
+  const [error, setError] = useState("");
+
+  useEffect(() => {
+    seedDemoUser();
+    if (isAuthenticated()) {
+      router.replace("/");
+    }
+  }, [router]);
+
+  const handleSubmit = (event: FormEvent<HTMLFormElement>) => {
+    event.preventDefault();
+    setError("");
+
+    if (!login.trim() || !password.trim()) {
+      setError("Заполните логин и пароль");
+      return;
+    }
+
+    const result = loginUser(login, password);
+    if (!result.ok) {
+      setError(result.message);
+      return;
+    }
+
+    router.push("/");
+  };
+
   return (
     <div className="min-h-screen bg-gradient-to-b from-sky-50 to-white text-gray-900">
       <div className="mx-auto flex min-h-screen max-w-4xl flex-col justify-center px-6 py-12 sm:px-10">
@@ -12,7 +47,7 @@ export default function Login() {
             Используйте телефон или почту, чтобы продолжить.
           </p>
 
-          <form className="space-y-4">
+          <form className="space-y-4" onSubmit={handleSubmit}>
             <div>
               <label className="mb-2 block text-sm font-medium text-gray-700" htmlFor="login">
                 Телефон или почта
@@ -22,6 +57,8 @@ export default function Login() {
                 name="login"
                 type="text"
                 autoComplete="username"
+                value={login}
+                onChange={(event) => setLogin(event.target.value)}
                 className="w-full rounded-lg border border-gray-200 bg-gray-50 px-4 py-3 text-sm text-gray-900 transition focus:border-sky-500 focus:bg-white focus:outline-none focus:ring-2 focus:ring-sky-100"
                 placeholder="example@mail.com"
               />
@@ -35,10 +72,13 @@ export default function Login() {
                 name="password"
                 type="password"
                 autoComplete="current-password"
+                value={password}
+                onChange={(event) => setPassword(event.target.value)}
                 className="w-full rounded-lg border border-gray-200 bg-gray-50 px-4 py-3 text-sm text-gray-900 transition focus:border-sky-500 focus:bg-white focus:outline-none focus:ring-2 focus:ring-sky-100"
                 placeholder="••••••••"
               />
             </div>
+            {error ? <p className="text-sm text-red-600">{error}</p> : null}
             <div className="flex items-center justify-between text-sm text-gray-600">
               <label className="inline-flex items-center gap-2">
                 <input
@@ -64,6 +104,7 @@ export default function Login() {
               Создать аккаунт
             </Link>
           </form>
+          <p className="mt-4 text-center text-xs text-gray-500">Демо вход: demo@corp.local / 123456</p>
           <p className="mt-6 text-center text-xs text-gray-500">
             Продолжая, вы соглашаетесь с условиями использования и подтверждаете ознакомление с политикой конфиденциальности.
           </p>
diff --git a/src/app/register/page.tsx b/src/app/register/page.tsx
index 788e8f3..83a907e 100644
--- a/src/app/register/page.tsx
+++ b/src/app/register/page.tsx
@@ -1,6 +1,67 @@
+"use client";
+
 import Link from "next/link";
+import { FormEvent, useEffect, useState } from "react";
+import { useRouter } from "next/navigation";
+import { isAuthenticated, loginUser, registerUser, seedDemoUser } from "../../lib/auth";
 
 export default function Register() {
+  const router = useRouter();
+  const [firstName, setFirstName] = useState("");
+  const [lastName, setLastName] = useState("");
+  const [login, setLogin] = useState("");
+  const [password, setPassword] = useState("");
+  const [confirmPassword, setConfirmPassword] = useState("");
+  const [accepted, setAccepted] = useState(false);
+  const [error, setError] = useState("");
+
+  useEffect(() => {
+    seedDemoUser();
+    if (isAuthenticated()) {
+      router.replace("/");
+    }
+  }, [router]);
+
+  const handleSubmit = (event: FormEvent<HTMLFormElement>) => {
+    event.preventDefault();
+    setError("");
+
+    if (!firstName.trim() || !lastName.trim() || !login.trim() || !password.trim() || !confirmPassword.trim()) {
+      setError("Заполните все поля");
+      return;
+    }
+
+    if (password.length < 6) {
+      setError("Пароль должен содержать минимум 6 символов");
+      return;
+    }
+
+    if (password !== confirmPassword) {
+      setError("Пароли не совпадают");
+      return;
+    }
+
+    if (!accepted) {
+      setError("Подтвердите согласие с условиями использования");
+      return;
+    }
+
+    const registration = registerUser({
+      firstName: firstName.trim(),
+      lastName: lastName.trim(),
+      login: login.trim(),
+      password,
+    });
+
+    if (!registration.ok) {
+      setError(registration.message);
+      return;
+    }
+
+    loginUser(login.trim(), password);
+    router.push("/");
+  };
+
   return (
     <div className="min-h-screen bg-gradient-to-b from-sky-50 to-white text-gray-900">
       <div className="mx-auto flex min-h-screen max-w-4xl flex-col justify-center px-6 py-12 sm:px-10">
@@ -12,7 +73,7 @@ export default function Register() {
             Создайте новый аккаунт, указав имя и контактные данные.
           </p>
 
-          <form className="space-y-4">
+          <form className="space-y-4" onSubmit={handleSubmit}>
             <div className="grid gap-4 sm:grid-cols-2">
               <div>
                 <label className="mb-2 block text-sm font-medium text-gray-700" htmlFor="firstName">
@@ -22,6 +83,8 @@ export default function Register() {
                   id="firstName"
                   name="firstName"
                   type="text"
+                  value={firstName}
+                  onChange={(event) => setFirstName(event.target.value)}
                   className="w-full rounded-lg border border-gray-200 bg-gray-50 px-4 py-3 text-sm text-gray-900 transition focus:border-sky-500 focus:bg-white focus:outline-none focus:ring-2 focus:ring-sky-100"
                   placeholder="Иван"
                 />
@@ -34,6 +97,8 @@ export default function Register() {
                   id="lastName"
                   name="lastName"
                   type="text"
+                  value={lastName}
+                  onChange={(event) => setLastName(event.target.value)}
                   className="w-full rounded-lg border border-gray-200 bg-gray-50 px-4 py-3 text-sm text-gray-900 transition focus:border-sky-500 focus:bg-white focus:outline-none focus:ring-2 focus:ring-sky-100"
                   placeholder="Иванов"
                 />
@@ -48,6 +113,8 @@ export default function Register() {
                 name="login"
                 type="text"
                 autoComplete="username"
+                value={login}
+                onChange={(event) => setLogin(event.target.value)}
                 className="w-full rounded-lg border border-gray-200 bg-gray-50 px-4 py-3 text-sm text-gray-900 transition focus:border-sky-500 focus:bg-white focus:outline-none focus:ring-2 focus:ring-sky-100"
                 placeholder="example@mail.com"
               />
@@ -62,6 +129,8 @@ export default function Register() {
                   name="password"
                   type="password"
                   autoComplete="new-password"
+                  value={password}
+                  onChange={(event) => setPassword(event.target.value)}
                   className="w-full rounded-lg border border-gray-200 bg-gray-50 px-4 py-3 text-sm text-gray-900 transition focus:border-sky-500 focus:bg-white focus:outline-none focus:ring-2 focus:ring-sky-100"
                   placeholder="••••••••"
                 />
@@ -75,6 +144,8 @@ export default function Register() {
                   name="confirmPassword"
                   type="password"
                   autoComplete="new-password"
+                  value={confirmPassword}
+                  onChange={(event) => setConfirmPassword(event.target.value)}
                   className="w-full rounded-lg border border-gray-200 bg-gray-50 px-4 py-3 text-sm text-gray-900 transition focus:border-sky-500 focus:bg-white focus:outline-none focus:ring-2 focus:ring-sky-100"
                   placeholder="••••••••"
                 />
@@ -83,11 +154,15 @@ export default function Register() {
             <label className="flex items-center gap-3 text-sm text-gray-700">
               <input
                 type="checkbox"
+                checked={accepted}
+                onChange={(event) => setAccepted(event.target.checked)}
                 className="h-4 w-4 rounded border-gray-300 text-sky-600 focus:ring-sky-500"
               />
               Я согласен с условиями использования
             </label>
 
+            {error ? <p className="text-sm text-red-600">{error}</p> : null}
+
             <button
               type="submit"
               className="flex w-full items-center justify-center rounded-lg bg-sky-400 px-4 py-3 text-sm font-semibold text-white shadow-sm transition hover:bg-sky-700 focus:outline-none focus:ring-2 focus:ring-sky-200"
diff --git a/src/components/AppShell.tsx b/src/components/AppShell.tsx
index 42b5e4b..3da8637 100644
--- a/src/components/AppShell.tsx
+++ b/src/components/AppShell.tsx
@@ -1,9 +1,24 @@
 "use client";
 
-import { Bell, Building2, FileSignature, FileText, Home as HomeIcon, MessageSquare, Search, Users, Wallet } from "lucide-react";
+import {
+  Bell,
+  Building2,
+  CalendarDays,
+  FileSignature,
+  FileText,
+  Home as HomeIcon,
+  LogOut,
+  Menu,
+  MessageSquare,
+  Search,
+  Users,
+  Wallet,
+  X,
+} from "lucide-react";
 import Link from "next/link";
-import { usePathname } from "next/navigation";
-import { ReactNode } from "react";
+import { usePathname, useRouter } from "next/navigation";
+import { ReactNode, useEffect, useRef, useState } from "react";
+import { isAuthenticated, logoutUser } from "../lib/auth";
 
 type AppShellProps = {
   children: ReactNode;
@@ -16,6 +31,15 @@ type PageHeaderProps = {
   eyebrow?: string;
 };
 
+type HeaderProps = {
+  onOpenLeftNav: () => void;
+  onOpenCalendar: () => void;
+};
+
+type LeftNavContentProps = {
+  onNavigate?: () => void;
+};
+
 const navItems = [
   { href: "/", label: "Лента", icon: HomeIcon },
   { href: "/messages", label: "Сообщения", icon: MessageSquare },
@@ -36,35 +60,206 @@ const calendarWeeks = [
   ["25", "26", "27", "28", "", "", ""],
 ];
 
-function Header() {
+function Header({ onOpenLeftNav, onOpenCalendar }: HeaderProps) {
+  const router = useRouter();
+
+  const [isNotificationsOpen, setIsNotificationsOpen] = useState(false);
+  const [isDesktopProfileMenuOpen, setIsDesktopProfileMenuOpen] = useState(false);
+  const [isMobileProfileMenuOpen, setIsMobileProfileMenuOpen] = useState(false);
+
+  const notificationsRef = useRef<HTMLDivElement>(null);
+  const desktopProfileRef = useRef<HTMLDivElement>(null);
+  const mobileProfileRef = useRef<HTMLDivElement>(null);
+
+  useEffect(() => {
+    const onClickOutside = (event: MouseEvent) => {
+      const target = event.target as Node;
+
+      const clickedOutsideNotifications = notificationsRef.current && !notificationsRef.current.contains(target);
+      const clickedOutsideDesktopProfile = desktopProfileRef.current && !desktopProfileRef.current.contains(target);
+      const clickedOutsideMobileProfile = mobileProfileRef.current && !mobileProfileRef.current.contains(target);
+
+      if (clickedOutsideNotifications) {
+        setIsNotificationsOpen(false);
+      }
+
+      if (clickedOutsideDesktopProfile) {
+        setIsDesktopProfileMenuOpen(false);
+      }
+
+      if (clickedOutsideMobileProfile) {
+        setIsMobileProfileMenuOpen(false);
+      }
+    };
+
+    const onEscape = (event: KeyboardEvent) => {
+      if (event.key === "Escape") {
+        setIsNotificationsOpen(false);
+        setIsDesktopProfileMenuOpen(false);
+        setIsMobileProfileMenuOpen(false);
+      }
+    };
+
+    document.addEventListener("mousedown", onClickOutside);
+    document.addEventListener("keydown", onEscape);
+
+    return () => {
+      document.removeEventListener("mousedown", onClickOutside);
+      document.removeEventListener("keydown", onEscape);
+    };
+  }, []);
+
+  const handleLogout = () => {
+    setIsNotificationsOpen(false);
+    setIsDesktopProfileMenuOpen(false);
+    setIsMobileProfileMenuOpen(false);
+    logoutUser();
+    router.push("/login");
+  };
+
   return (
-    <header className="sticky top-0 z-30 border-b border-slate-100 bg-white/90 backdrop-blur">
-      <div className="mx-auto flex h-14 max-w-6xl items-center gap-4 px-4 sm:px-8">
-        <Link href="/" className="flex items-center gap-2">
-          <img src="/logo.png" alt="Логотип" className="h-11 w-auto" />
-        </Link>
-        <div className="hidden flex-1 items-center justify-center md:flex">
-          <div className="relative w-full max-w-xl">
-            <Search size={16} className="pointer-events-none absolute left-4 top-1/2 -translate-y-1/2 text-gray-400" />
-            <input
-              type="text"
-              className="w-full rounded-full border border-gray-200 bg-gray-50 py-2.5 pl-11 pr-4 text-sm text-gray-800 transition focus:border-sky-500 focus:bg-white focus:outline-none focus:ring-2 focus:ring-sky-100"
-              placeholder="Поиск"
-            />
+    <header className="sticky top-0 z-40 border-b border-slate-100 bg-white/95 backdrop-blur">
+      <div className="mx-auto max-w-6xl px-4 sm:px-8">
+        <div className="hidden h-14 items-center gap-4 lg:flex">
+          <Link href="/" className="flex items-center gap-2">
+            <img src="/logo.png" alt="Логотип" className="h-11 w-auto" />
+          </Link>
+
+          <div className="flex flex-1 items-center justify-center">
+            <div className="relative w-full max-w-xl">
+              <Search size={16} className="pointer-events-none absolute left-4 top-1/2 -translate-y-1/2 text-gray-400" />
+              <input
+                type="text"
+                className="w-full rounded-full border border-gray-200 bg-gray-50 py-2.5 pl-11 pr-4 text-sm text-gray-800 transition focus:border-sky-500 focus:bg-white focus:outline-none focus:ring-2 focus:ring-sky-100"
+                placeholder="Поиск"
+              />
+            </div>
+          </div>
+
+          <div className="ml-auto flex items-center gap-2">
+            <div ref={notificationsRef} className="relative">
+              <button
+                type="button"
+                onClick={() => {
+                  setIsNotificationsOpen((prev) => !prev);
+                  setIsDesktopProfileMenuOpen(false);
+                }}
+                className="flex h-10 w-10 items-center justify-center rounded-full hover:bg-slate-100"
+                aria-haspopup="menu"
+                aria-expanded={isNotificationsOpen}
+                aria-label="Открыть уведомления"
+              >
+                <Bell size={18} className="text-gray-600" />
+              </button>
+
+              {isNotificationsOpen ? (
+                <div className="absolute right-0 top-12 z-40 w-56 rounded-xl bg-white p-3 text-sm text-gray-700 shadow-lg ring-1 ring-gray-100">
+                  новых уведомлений не
+                </div>
+              ) : null}
+            </div>
+
+            <div ref={desktopProfileRef} className="relative">
+              <button
+                type="button"
+                onClick={() => {
+                  setIsDesktopProfileMenuOpen((prev) => !prev);
+                  setIsNotificationsOpen(false);
+                }}
+                className="flex h-10 w-10 items-center justify-center rounded-full bg-sky-400 text-sm font-semibold text-white"
+                aria-haspopup="menu"
+                aria-expanded={isDesktopProfileMenuOpen}
+                aria-label="Открыть меню профиля"
+              >
+                КМ
+              </button>
+
+              {isDesktopProfileMenuOpen ? (
+                <div className="absolute right-0 top-12 z-40 w-44 rounded-xl bg-white p-2 shadow-lg ring-1 ring-gray-100">
+                  <button
+                    type="button"
+                    onClick={handleLogout}
+                    className="flex w-full items-center gap-2 rounded-lg px-3 py-2 text-sm text-red-600 hover:bg-red-50"
+                  >
+                    <LogOut size={16} />
+                    Выйти
+                  </button>
+                </div>
+              ) : null}
+            </div>
           </div>
         </div>
-        <div className="ml-auto flex items-center gap-1 sm:gap-2">
-          <button className="flex h-10 w-10 items-center justify-center rounded-full hover:bg-slate-100">
-            <Bell size={18} className="text-gray-600" />
-          </button>
-          <div className="ml-1 flex h-10 w-10 items-center justify-center rounded-full bg-sky-400 text-sm font-semibold text-white">КМ</div>
+
+        <div className="h-14 lg:hidden">
+          <div className="relative flex h-full items-center justify-between">
+            <button
+              type="button"
+              onClick={onOpenLeftNav}
+              className="flex h-10 w-10 items-center justify-center rounded-full hover:bg-slate-100"
+              aria-label="Открыть левое меню"
+            >
+              <Menu size={20} className="text-gray-700" />
+            </button>
+
+            <Link href="/" className="absolute left-1/2 -translate-x-1/2">
+              <img src="/logo.png" alt="Логотип" className="h-10 w-auto" />
+            </Link>
+
+            <button
+              type="button"
+              onClick={onOpenCalendar}
+              className="flex h-10 w-10 items-center justify-center rounded-full hover:bg-slate-100"
+              aria-label="Открыть календарь"
+            >
+              <CalendarDays size={20} className="text-gray-700" />
+            </button>
+          </div>
+        </div>
+
+        <div className="pb-3 lg:hidden">
+          <div className="flex items-center gap-2">
+            <div className="relative flex-1">
+              <Search size={16} className="pointer-events-none absolute left-3 top-1/2 -translate-y-1/2 text-gray-400" />
+              <input
+                type="text"
+                className="w-full rounded-full border border-gray-200 bg-gray-50 py-2.5 pl-10 pr-4 text-sm text-gray-800 transition focus:border-sky-500 focus:bg-white focus:outline-none focus:ring-2 focus:ring-sky-100"
+                placeholder="Поиск"
+              />
+            </div>
+
+            <div ref={mobileProfileRef} className="relative">
+              <button
+                type="button"
+                onClick={() => setIsMobileProfileMenuOpen((prev) => !prev)}
+                className="flex h-10 w-10 items-center justify-center rounded-full bg-sky-400 text-sm font-semibold text-white"
+                aria-haspopup="menu"
+                aria-expanded={isMobileProfileMenuOpen}
+                aria-label="Открыть меню профиля"
+              >
+                КМ
+              </button>
+
+              {isMobileProfileMenuOpen ? (
+                <div className="absolute right-0 top-12 z-40 w-44 rounded-xl bg-white p-2 shadow-lg ring-1 ring-gray-100">
+                  <button
+                    type="button"
+                    onClick={handleLogout}
+                    className="flex w-full items-center gap-2 rounded-lg px-3 py-2 text-sm text-red-600 hover:bg-red-50"
+                  >
+                    <LogOut size={16} />
+                    Выйти
+                  </button>
+                </div>
+              ) : null}
+            </div>
+          </div>
         </div>
       </div>
     </header>
   );
 }
 
-function LeftNav() {
+function LeftNavContent({ onNavigate }: LeftNavContentProps) {
   const pathname = usePathname();
 
   const navLinkClass = (href: string) =>
@@ -75,68 +270,80 @@ function LeftNav() {
   const navIconClass = (href: string) => (pathname === href ? "text-sky-700" : "text-gray-400");
 
   return (
-    <aside className="hidden w-64 flex-shrink-0 lg:block">
-      <div className="sticky top-8 space-y-4">
-        <div className="rounded-2xl bg-white p-5 shadow-sm ring-1 ring-gray-100">
-          <div className="mb-4 flex items-center gap-3">
-            <div className="flex h-11 w-11 items-center justify-center rounded-full bg-sky-400 text-sm font-semibold text-white">КМ</div>
-            <div>
-              <p className="text-sm font-semibold text-gray-900">Константин Макаев</p>
-              <p className="text-xs text-gray-500">Онлайн</p>
-            </div>
-          </div>
-          <div className="space-y-2 text-sm text-gray-700">
-            {navItems.map(({ href, label, icon: Icon }) => (
-              <Link key={href} href={href} className={navLinkClass(href)}>
-                <Icon size={18} className={navIconClass(href)} />
-                {label}
-              </Link>
-            ))}
-          </div>
+    <div className="rounded-2xl bg-white p-5 shadow-sm ring-1 ring-gray-100">
+      <div className="mb-4 flex items-center gap-3">
+        <div className="flex h-11 w-11 items-center justify-center rounded-full bg-sky-400 text-sm font-semibold text-white">КМ</div>
+        <div>
+          <p className="text-sm font-semibold text-gray-900">Константин Макаев</p>
+          <p className="text-xs text-gray-500">Онлайн</p>
         </div>
       </div>
+      <div className="space-y-2 text-sm text-gray-700">
+        {navItems.map(({ href, label, icon: Icon }) => (
+          <Link key={href} href={href} className={navLinkClass(href)} onClick={onNavigate}>
+            <Icon size={18} className={navIconClass(href)} />
+            {label}
+          </Link>
+        ))}
+      </div>
+    </div>
+  );
+}
+
+function LeftNav() {
+  return (
+    <aside className="hidden w-64 flex-shrink-0 lg:block">
+      <div className="sticky top-8 space-y-4">
+        <LeftNavContent />
+      </div>
     </aside>
   );
 }
 
+function CalendarCard() {
+  return (
+    <div className="rounded-2xl bg-white p-5 shadow-sm ring-1 ring-gray-100">
+      <div className="flex items-center justify-between text-sm font-semibold text-gray-900">
+        <span>Календарь</span>
+        <span className="text-xs font-normal text-gray-500">Февраль 2026</span>
+      </div>
+      <div className="mt-4 grid grid-cols-7 gap-1 text-center text-xs text-gray-500">
+        {weekdays.map((day) => (
+          <div key={day} className="py-1 font-medium">
+            {day}
+          </div>
+        ))}
+      </div>
+      <div className="mt-1 grid grid-cols-7 gap-1 text-sm text-gray-800">
+        {calendarWeeks.map((week, wi) =>
+          week.map((day, di) => {
+            const isToday = day === "18";
+            return (
+              <div
+                key={`${wi}-${di}`}
+                className={`flex h-9 items-center justify-center rounded-full ${
+                  day
+                    ? isToday
+                      ? "bg-sky-100 text-sky-800 font-semibold ring-1 ring-sky-200"
+                      : "hover:bg-sky-50"
+                    : ""
+                }`}
+              >
+                {day}
+              </div>
+            );
+          })
+        )}
+      </div>
+    </div>
+  );
+}
+
 function Calendar() {
   return (
     <aside className="hidden w-72 flex-shrink-0 space-y-4 lg:block">
       <div className="sticky top-8 space-y-4">
-        <div className="rounded-2xl bg-white p-5 shadow-sm ring-1 ring-gray-100">
-          <div className="flex items-center justify-between text-sm font-semibold text-gray-900">
-            <span>Календарь</span>
-            <span className="text-xs font-normal text-gray-500">Февраль 2026</span>
-          </div>
-          <div className="mt-4 grid grid-cols-7 gap-1 text-center text-xs text-gray-500">
-            {weekdays.map((day) => (
-              <div key={day} className="py-1 font-medium">
-                {day}
-              </div>
-            ))}
-          </div>
-          <div className="mt-1 grid grid-cols-7 gap-1 text-sm text-gray-800">
-            {calendarWeeks.map((week, wi) =>
-              week.map((day, di) => {
-                const isToday = day === "18";
-                return (
-                  <div
-                    key={`${wi}-${di}`}
-                    className={`flex h-9 items-center justify-center rounded-full ${
-                      day
-                        ? isToday
-                          ? "bg-sky-100 text-sky-800 font-semibold ring-1 ring-sky-200"
-                          : "hover:bg-sky-50"
-                        : ""
-                    }`}
-                  >
-                    {day}
-                  </div>
-                );
-              })
-            )}
-          </div>
-        </div>
+        <CalendarCard />
       </div>
     </aside>
   );
@@ -160,14 +367,98 @@ export function PageHeader({ title, subtitle, badge, eyebrow = "Раздел" }:
 }
 
 export function AppShell({ children }: AppShellProps) {
+  const router = useRouter();
+  const pathname = usePathname();
+
+  const [isMobileLeftNavOpen, setIsMobileLeftNavOpen] = useState(false);
+  const [isMobileCalendarOpen, setIsMobileCalendarOpen] = useState(false);
+
+  useEffect(() => {
+    if (!isAuthenticated()) {
+      router.replace("/login");
+    }
+  }, [router]);
+
+  useEffect(() => {
+    setIsMobileLeftNavOpen(false);
+    setIsMobileCalendarOpen(false);
+  }, [pathname]);
+
+  useEffect(() => {
+    if (isMobileLeftNavOpen || isMobileCalendarOpen) {
+      document.body.style.overflow = "hidden";
+      return;
+    }
+
+    document.body.style.overflow = "";
+
+    return () => {
+      document.body.style.overflow = "";
+    };
+  }, [isMobileLeftNavOpen, isMobileCalendarOpen]);
+
   return (
     <div className="min-h-screen bg-gradient-to-b from-sky-50 via-white to-white text-gray-900">
-      <Header />
-      <div className="mx-auto flex min-h-screen max-w-6xl gap-6 px-4 py-8 sm:px-8">
+      <Header onOpenLeftNav={() => setIsMobileLeftNavOpen(true)} onOpenCalendar={() => setIsMobileCalendarOpen(true)} />
+      <div className="mx-auto flex min-h-screen max-w-6xl gap-6 px-4 py-6 sm:px-8 lg:py-8">
         <LeftNav />
         <main className="flex-1 space-y-6">{children}</main>
         <Calendar />
       </div>
+
+      <div className={`fixed inset-0 z-50 lg:hidden ${isMobileLeftNavOpen ? "pointer-events-auto" : "pointer-events-none"}`}>
+        <button
+          type="button"
+          className={`absolute inset-0 bg-black/40 transition-opacity ${isMobileLeftNavOpen ? "opacity-100" : "opacity-0"}`}
+          onClick={() => setIsMobileLeftNavOpen(false)}
+          aria-label="Закрыть левое меню"
+        />
+        <div
+          className={`absolute inset-y-0 left-0 w-full overflow-y-auto bg-white p-4 transition-transform duration-300 ${
+            isMobileLeftNavOpen ? "translate-x-0" : "-translate-x-full"
+          }`}
+        >
+          <div className="mb-4 flex items-center justify-between">
+            <p className="text-sm font-semibold text-gray-900">Меню</p>
+            <button
+              type="button"
+              onClick={() => setIsMobileLeftNavOpen(false)}
+              className="flex h-10 w-10 items-center justify-center rounded-full hover:bg-slate-100"
+              aria-label="Закрыть меню"
+            >
+              <X size={20} className="text-gray-700" />
+            </button>
+          </div>
+          <LeftNavContent onNavigate={() => setIsMobileLeftNavOpen(false)} />
+        </div>
+      </div>
+
+      <div className={`fixed inset-0 z-50 lg:hidden ${isMobileCalendarOpen ? "pointer-events-auto" : "pointer-events-none"}`}>
+        <button
+          type="button"
+          className={`absolute inset-0 bg-black/40 transition-opacity ${isMobileCalendarOpen ? "opacity-100" : "opacity-0"}`}
+          onClick={() => setIsMobileCalendarOpen(false)}
+          aria-label="Закрыть календарь"
+        />
+        <div
+          className={`absolute inset-y-0 right-0 w-full overflow-y-auto bg-white p-4 transition-transform duration-300 ${
+            isMobileCalendarOpen ? "translate-x-0" : "translate-x-full"
+          }`}
+        >
+          <div className="mb-4 flex items-center justify-between">
+            <p className="text-sm font-semibold text-gray-900">Календарь</p>
+            <button
+              type="button"
+              onClick={() => setIsMobileCalendarOpen(false)}
+              className="flex h-10 w-10 items-center justify-center rounded-full hover:bg-slate-100"
+              aria-label="Закрыть календарь"
+            >
+              <X size={20} className="text-gray-700" />
+            </button>
+          </div>
+          <CalendarCard />
+        </div>
+      </div>
     </div>
   );
 }
diff --git a/src/lib/auth.ts b/src/lib/auth.ts
new file mode 100644
index 0000000..80a884c
--- /dev/null
+++ b/src/lib/auth.ts
@@ -0,0 +1,110 @@
+export type AuthUser = {
+  id: string;
+  firstName: string;
+  lastName: string;
+  login: string;
+  password: string;
+};
+
+const USERS_KEY = "corp.front.users";
+const SESSION_KEY = "corp.front.session";
+
+function isBrowser() {
+  return typeof window !== "undefined";
+}
+
+function loadUsers(): AuthUser[] {
+  if (!isBrowser()) {
+    return [];
+  }
+
+  const raw = window.localStorage.getItem(USERS_KEY);
+  if (!raw) {
+    return [];
+  }
+
+  try {
+    const parsed = JSON.parse(raw) as AuthUser[];
+    return Array.isArray(parsed) ? parsed : [];
+  } catch {
+    return [];
+  }
+}
+
+function saveUsers(users: AuthUser[]) {
+  if (!isBrowser()) {
+    return;
+  }
+
+  window.localStorage.setItem(USERS_KEY, JSON.stringify(users));
+}
+
+export function seedDemoUser() {
+  const users = loadUsers();
+  const exists = users.some((u) => u.login.toLowerCase() === "demo@corp.local");
+
+  if (exists) {
+    return;
+  }
+
+  users.push({
+    id: "demo-user",
+    firstName: "Демо",
+    lastName: "Пользователь",
+    login: "demo@corp.local",
+    password: "123456",
+  });
+
+  saveUsers(users);
+}
+
+export function registerUser(payload: Omit<AuthUser, "id">): { ok: true } | { ok: false; message: string } {
+  const users = loadUsers();
+  const normalizedLogin = payload.login.trim().toLowerCase();
+
+  const alreadyExists = users.some((u) => u.login.toLowerCase() === normalizedLogin);
+  if (alreadyExists) {
+    return { ok: false, message: "Пользователь с таким логином уже существует" };
+  }
+
+  users.push({
+    id: crypto.randomUUID(),
+    ...payload,
+    login: normalizedLogin,
+  });
+
+  saveUsers(users);
+  return { ok: true };
+}
+
+export function loginUser(login: string, password: string): { ok: true } | { ok: false; message: string } {
+  const users = loadUsers();
+  const normalizedLogin = login.trim().toLowerCase();
+
+  const user = users.find((u) => u.login.toLowerCase() === normalizedLogin && u.password === password);
+  if (!user) {
+    return { ok: false, message: "Неверный логин или пароль" };
+  }
+
+  if (isBrowser()) {
+    window.localStorage.setItem(SESSION_KEY, user.id);
+  }
+
+  return { ok: true };
+}
+
+export function logoutUser() {
+  if (!isBrowser()) {
+    return;
+  }
+
+  window.localStorage.removeItem(SESSION_KEY);
+}
+
+export function isAuthenticated() {
+  if (!isBrowser()) {
+    return false;
+  }
+
+  return Boolean(window.localStorage.getItem(SESSION_KEY));
+}