feat: add cross-platform PWA install prompt

src/components/AdminShell.tsx

@@ -12,6 +12,7 @@ import {
 import { useNavigate } from "react-router-dom";
 import { useAuth } from "../lib/auth";
 import { initials, cn } from "../lib/format";
+import { InstallAppPrompt } from "./InstallAppPrompt";
 
 interface NavItem {
   to: string;
@@ -131,6 +132,9 @@ export function AdminShell() {
             </div>
             <span className="text-sm font-extrabold">Admin</span>
           </div>
+          <div className="ml-auto w-auto">
+            <InstallAppPrompt />
+          </div>
         </header>
         <main className="flex-1 overflow-y-auto">
           <Outlet key={location.pathname} />

src/components/AppShell.tsx

@@ -19,6 +19,7 @@ import {
 import { useAuth } from "../lib/auth";
 import { initials, cn } from "../lib/format";
 import { DemoSwitcher } from "./DemoSwitcher";
+import { InstallAppPrompt } from "./InstallAppPrompt";
 
 interface NavItem {
   to: string;
@@ -164,6 +165,9 @@ export function AppShell() {
             </div>
             <span className="text-sm font-extrabold">AgendaMax</span>
           </div>
+          <div className="ml-auto w-auto">
+            <InstallAppPrompt />
+          </div>
         </header>
         <main className="flex-1 overflow-y-auto">
           <Outlet key={location.pathname} />

src/components/InstallAppPrompt.tsx

@@ -0,0 +1,29 @@
+import { useState } from "react";
+import { Download, PlusSquare, Share } from "lucide-react";
+import { Modal } from "./Modal";
+import { useInstallPrompt } from "../lib/useInstallPrompt";
+
+export function InstallAppPrompt() {
+  const { state, install } = useInstallPrompt();
+  const [iosOpen, setIosOpen] = useState(false);
+
+  if (state === "unsupported" || state === "installed") return null;
+  if (state === "ios-instructions") {
+    return (
+      <>
+        <button type="button" className="btn btn-secondary w-full justify-start" onClick={() => setIosOpen(true)}>
+          <Download className="h-4 w-4" /> Instalar AgendaMax
+        </button>
+        <Modal open={iosOpen} onClose={() => setIosOpen(false)} title="Instalar AgendaMax" subtitle="Safari lo añade a tu pantalla de inicio.">
+          <div className="safe-area-bottom">
+            <ol className="space-y-3 text-sm text-slate-600">
+              <li className="flex gap-3"><Share className="mt-0.5 h-5 w-5 shrink-0 text-brand-600" /><span>Toca <strong>Compartir</strong> en la barra de Safari.</span></li>
+              <li className="flex gap-3"><PlusSquare className="mt-0.5 h-5 w-5 shrink-0 text-brand-600" /><span>Elige <strong>Añadir a pantalla de inicio</strong> y confirma.</span></li>
+            </ol>
+          </div>
+        </Modal>
+      </>
+    );
+  }
+  return <button type="button" className="btn btn-secondary w-full justify-start" onClick={() => void install()}><Download className="h-4 w-4" /> Instalar AgendaMax</button>;
+}

src/index.css

@@ -281,6 +281,9 @@ body {
 .btn-danger:hover:not(:disabled) {
   background: #fecaca;
 }
+.safe-area-bottom {
+  padding-bottom: max(0.75rem, env(safe-area-inset-bottom));
+}
 
 @layer components {
   .input,

src/lib/useInstallPrompt.ts

@@ -0,0 +1,65 @@
+import { useEffect, useState } from "react";
+
+export type InstallPromptState = "unsupported" | "available" | "ios-instructions" | "installed";
+
+interface BeforeInstallPromptEvent extends Event {
+  prompt: () => Promise<void>;
+  userChoice: Promise<{ outcome: "accepted" | "dismissed"; platform: string }>;
+}
+
+function isStandalone() {
+  return window.matchMedia("(display-mode: standalone)").matches ||
+    ("standalone" in navigator && Boolean((navigator as Navigator & { standalone?: boolean }).standalone));
+}
+
+function isIOSSafari() {
+  const ua = navigator.userAgent;
+  const ios = /iPad|iPhone|iPod/.test(ua) || (navigator.platform === "MacIntel" && navigator.maxTouchPoints > 1);
+  return ios && /Safari/i.test(ua) && !/CriOS|FxiOS|EdgiOS|OPiOS/i.test(ua);
+}
+
+export function useInstallPrompt() {
+  const [state, setState] = useState<InstallPromptState>(() => {
+    if (typeof window === "undefined") return "unsupported";
+    if (isStandalone()) return "installed";
+    return isIOSSafari() ? "ios-instructions" : "unsupported";
+  });
+  const [deferred, setDeferred] = useState<BeforeInstallPromptEvent | null>(null);
+  const [dismissed, setDismissed] = useState(false);
+
+  useEffect(() => {
+    if (isStandalone()) {
+      setState("installed");
+      return;
+    }
+
+    const onBeforeInstallPrompt = (event: Event) => {
+      event.preventDefault();
+      setDeferred(event as BeforeInstallPromptEvent);
+      setState("available");
+    };
+    const onInstalled = () => {
+      setDeferred(null);
+      setState("installed");
+    };
+
+    window.addEventListener("beforeinstallprompt", onBeforeInstallPrompt);
+    window.addEventListener("appinstalled", onInstalled);
+    return () => {
+      window.removeEventListener("beforeinstallprompt", onBeforeInstallPrompt);
+      window.removeEventListener("appinstalled", onInstalled);
+    };
+  }, []);
+
+  const install = async () => {
+    if (!deferred) return;
+    const event = deferred;
+    setDeferred(null);
+    await event.prompt();
+    const choice = await event.userChoice;
+    if (choice.outcome === "accepted") setState("installed");
+    else setDismissed(true);
+  };
+
+  return { state: dismissed ? "unsupported" : state, install, dismiss: () => setDismissed(true) };
+}

src/pages/LoginPage.tsx

@@ -4,6 +4,7 @@ import { Sparkles, ArrowRight, Mail, Lock, AlertCircle, Wand2 } from "lucide-rea
 import { useAuth } from "../lib/auth";
 import { api } from "../lib/api";
 import { Spinner } from "../components/ui";
+import { InstallAppPrompt } from "../components/InstallAppPrompt";
 
 const DEMO = import.meta.env.DEV || import.meta.env.VITE_DEMO_UI === "1";
 
@@ -156,6 +157,10 @@ export function LoginPage() {
               </button>
             </form>
 
+            <div className="mx-auto mt-4 max-w-sm">
+              <InstallAppPrompt />
+            </div>
+
             {DEMO && (
               <>
                 <div className="mt-5 flex items-center gap-2 text-xs font-medium text-slate-400">