Add the Install the app bottom sheet for mobile browsers

- New InstallSheet mounted in the root layout: appears ~1s after load on
  iOS/Android phones and tablets, over any screen including the key gate,
  with a dimmed backdrop. Never on desktop, never in standalone mode, and
  at most once per 7 days after a dismissal (localStorage).
- Platform/browser detection (lib/install.ts): iPhone/iPad incl. iPadOS
  reporting as Mac with touch, Android, Safari vs Chrome vs other vs
  in-app browsers, with step 1 adapted accordingly.
- iOS: numbered steps with chips (Safari, Share, ... , More, Add to Home
  Screen) and the accent Add pill. Android: captured beforeinstallprompt
  turns into a native Install button; fallback steps use Install app /
  Add to Home screen chips and an accent Install pill.
- Close via X, backdrop, Escape or swipe-down on the handle; the site is
  untouched afterwards. Anchored to 100dvh so browser toolbars never hide
  the last step; pb-safe respects the home indicator.
- Dark sheet by default; light only when the app theme was explicitly set
  to light. Settings gains a mobile-only Install app row that reopens it.
- The inline head script captures beforeinstallprompt before hydration and
  records appinstalled. Old InstallHint banner removed.
- Tests: new install-sheet suite (45 checks across iPhone Safari/Chrome/
  in-app, Android Chrome/Samsung, desktop, prompt path, dismissal, 7-day
  expiry, standalone, Settings row, both themes); pwa suite updated.

README.md

@@ -395,13 +395,18 @@ Decks are organised into folders — the same way you'd file paper notes.
 
 Freezmo ships as an installable Progressive Web App with iOS in mind.
 
-**iOS / iPadOS (Safari):** open the app → **Share** → **Add to Home Screen**. The app shows a
+Phones and tablets get an **"Install the app" bottom sheet** about a second after load (never on
-one-time hint explaining exactly this. It launches full-screen in standalone mode (no browser
+desktop, never when already installed, and at most once per 7 days after a dismissal). It is a
-chrome), respects the notch/home-indicator safe areas, and has an iOS-style bottom tab bar
+native-feeling sheet with the Freezmo card, numbered steps and chips for the exact buttons to tap,
-(Library · New deck · Settings) with sheet-style dialogs.
+plus an accent confirmation pill. Close it with the X, the backdrop, Escape, or a swipe down — the
+site keeps working normally. On iOS the steps adapt to the browser (Safari, Chrome, in-app), and
+on Android Chrome a captured `beforeinstallprompt` turns into a real **Install** button. The sheet
+can be reopened any time from **Settings → Install app** (mobile only).
 
-**Android (Chrome):** Chrome offers "Install app" from the ⋮ menu; Freezmo also works offline for
+It launches full-screen in standalone mode (no browser chrome), respects the notch/home-indicator
-the parts that don't need a model.
+safe areas, and has an iOS-style bottom tab bar (Library · New deck · Settings) with sheet-style
+dialogs. Android Chrome also offers "Install app" from the ⋮ menu; Freezmo works offline for the
+parts that don't need a model.
 
 What's included:
 
@@ -430,8 +435,9 @@ self-hosted study app with no accounts, no database and no server-side state.
   production `.next` output for a test key, and by restarting the server (which remembers nothing).
 - **No server-side injection surface.** The Ollama endpoint and model names come only from the
   server's `.env`; the client cannot point the server at another host. Model output is validated with
-  zod and rendered as text — there is no `dangerouslySetInnerHTML` except one static theme script,
+  zod and rendered as text — there is no `dangerouslySetInnerHTML` except two static inline scripts
-  so a deck cannot inject markup or script (React escapes everything).
+  (the pre-paint theme choice and the `beforeinstallprompt` capture), so a deck cannot inject markup
+  or script (React escapes everything).
 - **Key-header sanitisation.** Keys from the client are stripped of control characters/whitespace
   and capped at 512 chars before they are used in an outbound header, so a crafted key cannot inject
   headers. Verified with a raw-socket CRLF attempt.
@@ -540,7 +546,7 @@ components/
     Flashcard.tsx MultipleChoice.tsx TrueFalse.tsx FillBlank.tsx
     Matching.tsx Ordering.tsx ShortAnswer.tsx shared.tsx index.tsx
   UploadScreen.tsx StudyFeed.tsx ResultsScreen.tsx DeckCard.tsx ApiKeyGate.tsx
-  TabBar.tsx InstallHint.tsx ServiceWorkerRegistrar.tsx FolderBar.tsx
+  InstallSheet.tsx TabBar.tsx ServiceWorkerRegistrar.tsx FolderBar.tsx
   LibraryScreen.tsx SettingsDialog.tsx AppHeader.tsx ThemeToggle.tsx icons.tsx ui.tsx
 lib/
   ollama.ts        server-only HTTP client (timeouts, auth, error mapping)
@@ -550,6 +556,7 @@ lib/
   config.ts        env config, cloud/direct model-name normalisation
   documents.ts     client-side PDF/DOCX/PPTX/ODT/text extraction
   folders.ts       folder library (create/rename/delete) in localStorage
+  install.ts       install-prompt platform/browser detection + 7-day dismissal
   settings.ts      browser-side settings (the user's API key) + auth headers
   use-health.ts    client hook for /api/health, re-runs when the key changes
   rate-limit.ts    in-memory sliding-window limiter for the API routes
@@ -760,6 +767,12 @@ Things I chose while building, with the reasoning:
     `/api/health`, so an invalid key and an unreachable Ollama are worded differently. The old
     dashboard banner is gone; key management stays in Settings, and removing the key brings the
     gate back. The gate covers `/`, `/create` and deck study, but never `/offline`.
+29. **The install prompt is a teaching sheet, not a nag.** It appears once, phones/tablets only,
+    a second after load, and never in standalone mode; dismissing it silences it for 7 days. It
+    detects iOS vs Android and Safari vs Chrome vs an in-app browser so step 1 always matches the
+    device, uses Chrome's deferred `beforeinstallprompt` for a one-tap install where available, and
+    stays reachable from Settings. It is mounted in the root layout, so it can appear over any
+    screen — including the key gate — without blocking the page underneath.
 14. **`gpt-oss:120b` does all content work — but it cannot read images** (`this model does not
     support image input`), so `VISION_MODEL` has to stay a multimodal model (`gemma4:31b-cloud`).
     Text-only inputs — pasted text, PDFs with a text layer, DOCX/PPTX/ODT — never touch the vision

app/layout.tsx

@@ -1,5 +1,6 @@
 import type { Metadata, Viewport } from "next";
 
+import { InstallSheet } from "@/components/InstallSheet";
 import { ServiceWorkerRegistrar } from "@/components/ServiceWorkerRegistrar";
 import "./globals.css";
 
@@ -51,15 +52,26 @@ export const viewport: Viewport = {
 /** Applies the saved theme before paint to avoid a flash. */
 const themeScript = `(function(){try{var s=localStorage.getItem('freezmo.theme');var d=s?s==='dark':window.matchMedia('(prefers-color-scheme: dark)').matches;if(d)document.documentElement.classList.add('dark');}catch(e){}})();`;
 
+/**
+ * Captures Chrome's `beforeinstallprompt` (it can fire before React hydrates)
+ * and records an install so the prompt never comes back. Static, no user data.
+ */
+const installScript = `(function(){try{
+window.addEventListener('beforeinstallprompt',function(e){e.preventDefault();window.__freezmoInstallPrompt=e;window.dispatchEvent(new Event('freezmo:installprompt'));});
+window.addEventListener('appinstalled',function(){try{localStorage.setItem('freezmo.install.installed','1')}catch(e){}window.dispatchEvent(new Event('freezmo:installed'));});
+}catch(e){}})();`;
+
 export default function RootLayout({ children }: { children: React.ReactNode }) {
   return (
     <html lang="en" suppressHydrationWarning>
       <head>
         <script dangerouslySetInnerHTML={{ __html: themeScript }} />
+        <script dangerouslySetInnerHTML={{ __html: installScript }} />
       </head>
       <body className="min-h-full antialiased">
         <div className="app-backdrop" aria-hidden />
         {children}
+        <InstallSheet />
         <ServiceWorkerRegistrar />
       </body>
     </html>

app/page.tsx

@@ -1,6 +1,5 @@
 import { ApiKeyGate } from "@/components/ApiKeyGate";
 import { AppHeader } from "@/components/AppHeader";
-import { InstallHint } from "@/components/InstallHint";
 import { LibraryScreen } from "@/components/LibraryScreen";
 import { MobileSidebar, Sidebar, SidebarOffset } from "@/components/Sidebar";
 import { TabBar } from "@/components/TabBar";
@@ -15,9 +14,6 @@ export default function HomePage() {
         <main className="min-w-0 flex-1">
           <AppHeader />
           <div className="mx-auto w-full max-w-6xl px-4 pb-tabbar lg:px-10 lg:pb-16">
-            <div className="mb-6">
-              <InstallHint />
-            </div>
             <LibraryScreen />
           </div>
           <TabBar />

components/InstallHint.tsx

@@ -1,64 +0,0 @@
-"use client";
-
-import { useEffect, useState } from "react";
-
-import { ShareIcon } from "@/components/icons";
-
-const DISMISS_KEY = "freezmo.installHintDismissed";
-
-/**
- * iOS has no `beforeinstallprompt`, so the only way to explain installing the
- * PWA is to point at the Share sheet. Shown once, only in iOS Safari, only
- * outside standalone mode.
- */
-export function InstallHint() {
-  const [visible, setVisible] = useState(false);
-
-  useEffect(() => {
-    try {
-      if (window.localStorage.getItem(DISMISS_KEY) === "1") return;
-      const ua = window.navigator.userAgent;
-      const isIos = /iPad|iPhone|iPod/.test(ua) || (ua.includes("Macintosh") && "ontouchend" in document);
-      const isSafari = /Safari/.test(ua) && !/CriOS|FxiOS|EdgiOS|OPiOS/.test(ua);
-      const standalone =
-        window.matchMedia("(display-mode: standalone)").matches ||
-        (window.navigator as unknown as { standalone?: boolean }).standalone === true;
-      if (isIos && isSafari && !standalone) setVisible(true);
-    } catch {
-      /* private mode */
-    }
-  }, []);
-
-  if (!visible) return null;
-
-  const dismiss = () => {
-    setVisible(false);
-    try {
-      window.localStorage.setItem(DISMISS_KEY, "1");
-    } catch {
-      /* ignore */
-    }
-  };
-
-  return (
-    <div className="glass-panel animate-rise flex items-start gap-3 rounded-[1.35rem] p-3.5 text-sm">
-      <ShareIcon className="mt-0.5 size-5 shrink-0 text-accent-600 dark:text-accent-300" />
-      <div className="flex-1">
-        <p className="font-semibold text-frost-950 dark:text-frost-50">Install Freezmo</p>
-        <p className="text-frost-600 dark:text-frost-300">
-          Tap <span className="font-medium">Share</span> then{" "}
-          <span className="font-medium">Add to Home Screen</span> for a full-screen, app-like
-          experience that works without the browser chrome.
-        </p>
-      </div>
-      <button
-        type="button"
-        onClick={dismiss}
-        aria-label="Dismiss install hint"
-        className="rounded-lg px-2 py-1 text-frost-400 transition-colors hover:bg-[var(--surface-sunken)]"
-      >
-        ✕
-      </button>
-    </div>
-  );
-}

components/InstallSheet.tsx

@@ -0,0 +1,348 @@
+"use client";
+
+import { AnimatePresence, motion, useDragControls, useReducedMotion } from "framer-motion";
+import { useCallback, useEffect, useState } from "react";
+
+import {
+  AddToHomeIcon,
+  ChromeIcon,
+  CompassIcon,
+  DownloadIcon,
+  EllipsisIcon,
+  MoreIcon,
+  PlusIcon,
+  ShareIcon,
+  SnowflakeIcon,
+  XIcon,
+} from "@/components/icons";
+import { Spinner } from "@/components/ui";
+import {
+  detectBrowser,
+  detectPlatform,
+  dismissInstallPrompt,
+  INSTALL_PROMPT_EVENT,
+  INSTALLED_EVENT,
+  installSheetTheme,
+  isDismissed,
+  isInstalled,
+  isStandalone,
+  markInstalled,
+  OPEN_INSTALL_EVENT,
+  type BeforeInstallPromptEvent,
+  type InstallBrowser,
+  type InstallPlatform,
+} from "@/lib/install";
+import { cn } from "@/lib/utils";
+
+type SheetInfo = {
+  platform: InstallPlatform;
+  browser: InstallBrowser;
+  theme: "dark" | "light";
+};
+
+/**
+ * "Install the app" bottom sheet. Mounted once in the root layout so it can
+ * appear over any screen (including the API-key gate) about a second after
+ * load. Phones/tablets only, never when already installed, and at most once
+ * per 7 days after a dismissal. Closing it leaves the site exactly as it was.
+ */
+export function InstallSheet() {
+  const [info, setInfo] = useState<SheetInfo | null>(null);
+  const [open, setOpen] = useState(false);
+  const [promptEvent, setPromptEvent] = useState<BeforeInstallPromptEvent | null>(null);
+  const [installing, setInstalling] = useState(false);
+  const dragControls = useDragControls();
+  const reduceMotion = useReducedMotion();
+  const domain = typeof window === "undefined" ? "" : window.location.host;
+
+  /** Everything needed to render the sheet, or null if it shouldn't appear. */
+  const prepare = useCallback((): SheetInfo | null => {
+    const platform = detectPlatform();
+    if (platform === "other" || isInstalled()) return null;
+    return { platform, browser: detectBrowser(platform), theme: installSheetTheme() };
+  }, []);
+
+  // Automatic prompt: about a second after load, unless dismissed recently.
+  useEffect(() => {
+    if (isStandalone()) {
+      markInstalled();
+      return;
+    }
+    const next = prepare();
+    if (!next || isDismissed()) return;
+    const timer = window.setTimeout(() => {
+      setInfo(next);
+      setOpen(true);
+    }, 1000);
+    return () => window.clearTimeout(timer);
+  }, [prepare]);
+
+  // Manual open from the Settings row (ignores the 7-day window).
+  useEffect(() => {
+    const onOpen = () => {
+      const next = prepare();
+      if (!next) return;
+      setInfo(next);
+      setOpen(true);
+    };
+    window.addEventListener(OPEN_INSTALL_EVENT, onOpen);
+    return () => window.removeEventListener(OPEN_INSTALL_EVENT, onOpen);
+  }, [prepare]);
+
+  // Chrome's deferred install prompt + the "installed" signal.
+  useEffect(() => {
+    const sync = () => setPromptEvent(window.__freezmoInstallPrompt ?? null);
+    const onInstalled = () => {
+      markInstalled();
+      setPromptEvent(null);
+      setInstalling(false);
+      setOpen(false);
+    };
+    window.addEventListener(INSTALL_PROMPT_EVENT, sync);
+    window.addEventListener(INSTALLED_EVENT, onInstalled);
+    window.addEventListener("appinstalled", onInstalled);
+    sync();
+    return () => {
+      window.removeEventListener(INSTALL_PROMPT_EVENT, sync);
+      window.removeEventListener(INSTALLED_EVENT, onInstalled);
+      window.removeEventListener("appinstalled", onInstalled);
+    };
+  }, []);
+
+  const close = useCallback(() => {
+    dismissInstallPrompt();
+    setOpen(false);
+    setInstalling(false);
+  }, []);
+
+  // Escape closes, like every other sheet in the app.
+  useEffect(() => {
+    if (!open) return;
+    const onKey = (event: KeyboardEvent) => {
+      if (event.key === "Escape") close();
+    };
+    window.addEventListener("keydown", onKey);
+    return () => window.removeEventListener("keydown", onKey);
+  }, [open, close]);
+
+  const runPrompt = async () => {
+    if (!promptEvent || installing) return;
+    setInstalling(true);
+    try {
+      await promptEvent.prompt();
+      const choice = await promptEvent.userChoice;
+      if (choice.outcome === "accepted") {
+        markInstalled();
+        setOpen(false);
+        setInstalling(false);
+        return;
+      }
+    } catch {
+      /* the native prompt can fail; the steps below still work */
+    }
+    setInstalling(false);
+  };
+
+  const steps: React.ReactNode[] = [];
+  if (info?.platform === "ios") {
+    if (info.browser !== "safari") {
+      steps.push(
+        <>
+          Open this page in <Chip icon={<CompassIcon className="size-3.5" />}>Safari</Chip>.
+        </>,
+      );
+    }
+    steps.push(
+      <>
+        Tap <Chip icon={<ShareIcon className="size-3.5" />}>Share</Chip> in the browser bar — in
+        some browsers it&rsquo;s under <Chip icon={<EllipsisIcon className="size-3.5" />}>⋯</Chip>.
+      </>,
+    );
+    steps.push(
+      <>
+        Tap <Chip icon={<MoreIcon className="size-3.5" />}>More</Chip> in the share sheet.
+      </>,
+    );
+    steps.push(
+      <>
+        Choose <Chip icon={<AddToHomeIcon className="size-3.5" />}>Add to Home Screen</Chip>.
+      </>,
+    );
+    steps.push(
+      <>
+        Tap <AccentPill icon={<PlusIcon className="size-3.5" />}>Add</AccentPill> to confirm.
+      </>,
+    );
+  } else if (info?.platform === "android") {
+    if (info.browser !== "chrome") {
+      steps.push(
+        <>
+          Open this page in <Chip icon={<ChromeIcon className="size-3.5" />}>Chrome</Chip>.
+        </>,
+      );
+    }
+    steps.push(
+      <>
+        Tap <Chip icon={<EllipsisIcon className="size-3.5" />}>⋯</Chip> in the top right of the
+        browser.
+      </>,
+    );
+    steps.push(
+      <>
+        Choose <Chip icon={<DownloadIcon className="size-3.5" />}>Install app</Chip> or{" "}
+        <Chip icon={<AddToHomeIcon className="size-3.5" />}>Add to Home screen</Chip>.
+      </>,
+    );
+    steps.push(
+      <>
+        Tap <AccentPill icon={<DownloadIcon className="size-3.5" />}>Install</AccentPill> to confirm.
+      </>,
+    );
+  }
+
+  const showNativePrompt = info?.platform === "android" && Boolean(promptEvent);
+
+  return (
+    // The sheet is dark by default; only an explicit light choice in the app
+    // switches the palette (the wrapper scopes the app's .dark tokens).
+    <div className={info?.theme === "light" ? undefined : "dark"}>
+      <AnimatePresence>
+        {open && info ? (
+          <div className="fixed inset-x-0 top-0 z-[60] h-dvh">
+            <motion.div
+              aria-hidden
+              onClick={close}
+              initial={{ opacity: 0 }}
+              animate={{ opacity: 1 }}
+              exit={{ opacity: 0 }}
+              transition={{ duration: 0.25 }}
+              className="absolute inset-0 bg-black/45 backdrop-blur-[2px]"
+            />
+            <motion.div
+              role="dialog"
+              aria-modal="true"
+              aria-labelledby="install-sheet-title"
+              drag="y"
+              dragControls={dragControls}
+              dragListener={false}
+              dragConstraints={{ top: 0, bottom: 0 }}
+              dragElastic={{ top: 0, bottom: 0.55 }}
+              onDragEnd={(_, gesture) => {
+                if (gesture.offset.y > 90 || gesture.delta.y > 140 || gesture.velocity.y > 700) close();
+              }}
+              initial={reduceMotion ? { opacity: 0 } : { y: "100%" }}
+              animate={reduceMotion ? { opacity: 1 } : { y: 0 }}
+              exit={reduceMotion ? { opacity: 0 } : { y: "100%" }}
+              transition={{ duration: 0.34, ease: [0.22, 1, 0.36, 1] }}
+              className="absolute inset-x-0 bottom-0 mx-auto w-full rounded-t-[28px] border border-b-0 border-[var(--hairline)] bg-[var(--surface)] shadow-[0_-20px_60px_-28px_rgb(0_0_0/0.5)] sm:max-w-xl"
+            >
+              <div className="thin-scroll max-h-[88dvh] overflow-y-auto px-5 pb-safe pt-2">
+                <div
+                  aria-hidden
+                  onPointerDown={(event) => dragControls.start(event)}
+                  className="mx-auto flex h-6 w-full cursor-grab touch-none items-center justify-center active:cursor-grabbing"
+                >
+                  <span className="h-1.5 w-10 rounded-full bg-[var(--text-subtle)] opacity-40" />
+                </div>
+
+                <div className="flex items-center justify-between gap-4">
+                  <h2
+                    id="install-sheet-title"
+                    className="text-[17px] font-semibold tracking-[-0.01em] text-[var(--text)]"
+                  >
+                    {info.platform === "ios"
+                      ? "Install Freezmo on iPhone"
+                      : "Install Freezmo on Android"}
+                  </h2>
+                  <button
+                    type="button"
+                    onClick={close}
+                    aria-label="Close"
+                    className="grid size-10 shrink-0 place-items-center rounded-full text-[var(--text-muted)] transition hover:bg-[var(--hover)] hover:text-[var(--text)]"
+                  >
+                    <XIcon className="size-[18px]" />
+                  </button>
+                </div>
+
+                {/* app card */}
+                <div className="mt-1 flex items-center gap-3 rounded-2xl border border-[var(--hairline)] bg-[var(--surface-sunken)] p-3">
+                  <span
+                    aria-hidden
+                    className="grid size-11 shrink-0 place-items-center rounded-xl bg-[var(--text)] text-[var(--page)]"
+                  >
+                    <SnowflakeIcon className="size-5" />
+                  </span>
+                  <span className="min-w-0">
+                    <span className="block text-[15px] font-semibold leading-tight text-[var(--text)]">
+                      Freezmo
+                    </span>
+                    <span className="block truncate text-[12.5px] text-[var(--text-subtle)]">
+                      {domain}
+                    </span>
+                  </span>
+                </div>
+
+                {showNativePrompt ? (
+                  <button
+                    type="button"
+                    onClick={() => void runPrompt()}
+                    disabled={installing}
+                    className="btn-primary mt-4 h-12 w-full rounded-[14px] text-[15px] font-medium disabled:cursor-not-allowed disabled:opacity-60"
+                  >
+                    {installing ? (
+                      <>
+                        <Spinner className="size-4" /> Installing…
+                      </>
+                    ) : (
+                      <>
+                        <DownloadIcon className="size-4" /> Install
+                      </>
+                    )}
+                  </button>
+                ) : null}
+
+                {showNativePrompt ? (
+                  <p className="mt-4 text-center text-[11.5px] text-[var(--text-subtle)]">
+                    Or install manually:
+                  </p>
+                ) : null}
+
+                <ol className={cn("space-y-3", showNativePrompt ? "mt-3" : "mt-4")}>
+                  {steps.map((step, index) => (
+                    <li
+                      key={index}
+                      className="flex items-start gap-2.5 text-[13.5px] leading-relaxed text-[var(--text-muted)]"
+                    >
+                      <span className="font-bold tabular-nums text-[var(--text)]">{index + 1}.</span>
+                      <span className="min-w-0 flex-1">{step}</span>
+                    </li>
+                  ))}
+                </ol>
+              </div>
+            </motion.div>
+          </div>
+        ) : null}
+      </AnimatePresence>
+    </div>
+  );
+}
+
+/** Small pill for a UI element the user has to tap. */
+function Chip({ icon, children }: { icon: React.ReactNode; children: React.ReactNode }) {
+  return (
+    <span className="mx-0.5 inline-flex translate-y-[1px] items-center gap-1 rounded-full border border-[var(--field-border)] bg-[var(--field)] px-2 py-[3px] text-[12px] font-semibold leading-none text-[var(--text)]">
+      <span aria-hidden>{icon}</span>
+      {children}
+    </span>
+  );
+}
+
+/** The one coloured element: the final confirmation button. */
+function AccentPill({ icon, children }: { icon: React.ReactNode; children: React.ReactNode }) {
+  return (
+    <span className="mx-0.5 inline-flex translate-y-[1px] items-center gap-1 rounded-full bg-accent-600 px-2.5 py-[3px] text-[12px] font-semibold leading-none text-white">
+      <span aria-hidden>{icon}</span>
+      {children}
+    </span>
+  );
+}

components/SettingsDialog.tsx

@@ -4,13 +4,15 @@ import { AnimatePresence, motion } from "framer-motion";
 import { useEffect, useState } from "react";
 
 import { cn } from "@/lib/utils";
+import { openInstallSheet, useInstallAvailable } from "@/lib/install";
 import { clearApiKey, saveSettings } from "@/lib/settings";
 import { useHealth } from "@/lib/use-health";
-import { AlertTriangleIcon, CheckCircleIcon, XCircleIcon } from "@/components/icons";
+import { AlertTriangleIcon, CheckCircleIcon, ChevronRightIcon, DownloadIcon, XCircleIcon } from "@/components/icons";
 import { Button, Spinner } from "@/components/ui";
 
 export function SettingsDialog({ open, onClose }: { open: boolean; onClose: () => void }) {
   const { health, loading, error, refresh, apiKey } = useHealth();
+  const installAvailable = useInstallAvailable();
   const [keyDraft, setKeyDraft] = useState(apiKey);
   const [reveal, setReveal] = useState(false);
   const [saved, setSaved] = useState(false);
@@ -145,6 +147,36 @@ export function SettingsDialog({ open, onClose }: { open: boolean; onClose: () =
               </div>
             </section>
 
+            {/* ------------------------------------------------ install */}
+            {installAvailable ? (
+              <section className="mb-4 rounded-2xl border border-[var(--hairline)] bg-[var(--surface-sunken)] p-1.5">
+                <button
+                  type="button"
+                  onClick={() => {
+                    onClose();
+                    openInstallSheet();
+                  }}
+                  className="flex w-full items-center gap-3 rounded-xl px-2.5 py-2 text-left transition hover:bg-[var(--hover)]"
+                >
+                  <span
+                    aria-hidden
+                    className="grid size-9 shrink-0 place-items-center rounded-xl border border-[var(--hairline)] bg-[var(--surface)] text-[var(--text-muted)]"
+                  >
+                    <DownloadIcon className="size-4" />
+                  </span>
+                  <span className="min-w-0 flex-1">
+                    <span className="block text-sm font-semibold text-frost-950 dark:text-frost-50">
+                      Install app
+                    </span>
+                    <span className="block text-[12px] text-[var(--text-subtle)]">
+                      Add Freezmo to your home screen
+                    </span>
+                  </span>
+                  <ChevronRightIcon className="size-4 shrink-0 text-[var(--text-subtle)]" />
+                </button>
+              </section>
+            ) : null}
+
             {loading && !health ? (
               <div className="flex items-center gap-3 py-6 text-sm text-slate-600 dark:text-slate-300">
                 <Spinner className="size-5" /> Checking Ollama…

components/icons.tsx

@@ -285,3 +285,54 @@ export function ExternalLinkIcon({ className }: IconProps) {
     </Svg>
   );
 }
+
+/* --- Install-sheet chips ------------------------------------------------ */
+
+export function CompassIcon({ className }: IconProps) {
+  return (
+    <Svg className={className}>
+      <circle cx="12" cy="12" r="9" />
+      <path d="m15.6 8.4-2.3 5.3-5.3 2.3 2.3-5.3 5.3-2.3Z" />
+    </Svg>
+  );
+}
+
+export function EllipsisIcon({ className }: IconProps) {
+  return (
+    <Svg className={className}>
+      <circle cx="5.5" cy="12" r="1.4" fill="currentColor" stroke="none" />
+      <circle cx="12" cy="12" r="1.4" fill="currentColor" stroke="none" />
+      <circle cx="18.5" cy="12" r="1.4" fill="currentColor" stroke="none" />
+    </Svg>
+  );
+}
+
+export function MoreIcon({ className }: IconProps) {
+  return (
+    <Svg className={className}>
+      <rect x="3.5" y="3.5" width="17" height="17" rx="5" />
+      <circle cx="8.4" cy="12" r="1.2" fill="currentColor" stroke="none" />
+      <circle cx="12" cy="12" r="1.2" fill="currentColor" stroke="none" />
+      <circle cx="15.6" cy="12" r="1.2" fill="currentColor" stroke="none" />
+    </Svg>
+  );
+}
+
+export function AddToHomeIcon({ className }: IconProps) {
+  return (
+    <Svg className={className}>
+      <rect x="4" y="4" width="16" height="16" rx="4.5" />
+      <path d="M12 8.8v6.4M8.8 12h6.4" />
+    </Svg>
+  );
+}
+
+export function ChromeIcon({ className }: IconProps) {
+  return (
+    <Svg className={className}>
+      <circle cx="12" cy="12" r="9" />
+      <circle cx="12" cy="12" r="3.4" />
+      <path d="M12 8.6V3M9.05 13.7 4.2 16.5M14.95 13.7l4.85 2.8" />
+    </Svg>
+  );
+}

lib/install.ts

@@ -0,0 +1,165 @@
+"use client";
+
+import { useEffect, useState } from "react";
+
+/**
+ * "Install the app" helpers: platform/browser detection plus the small amount
+ * of persistence the bottom sheet needs.
+ *
+ * Everything here is browser-only and side-effect free until called. The
+ * install prompt is never shown on desktop, never inside an installed app, and
+ * at most once per 7 days after a dismissal.
+ */
+
+export type InstallPlatform = "ios" | "android" | "other";
+export type InstallBrowser = "safari" | "chrome" | "other" | "in-app";
+
+/** Chrome's `beforeinstallprompt` event (not in the DOM typings). */
+export type BeforeInstallPromptEvent = Event & {
+  prompt: () => Promise<void>;
+  userChoice: Promise<{ outcome: "accepted" | "dismissed"; platform: string }>;
+};
+
+declare global {
+  interface Window {
+    __freezmoInstallPrompt?: BeforeInstallPromptEvent;
+  }
+}
+
+const DISMISS_KEY = "freezmo.install.dismissedAt";
+const INSTALLED_KEY = "freezmo.install.installed";
+const THEME_KEY = "freezmo.theme";
+
+/** How long a dismissal silences the automatic prompt. */
+export const INSTALL_REMIND_MS = 7 * 24 * 60 * 60 * 1000;
+
+/** Fired by Settings to open the sheet manually (ignores the dismissal). */
+export const OPEN_INSTALL_EVENT = "freezmo:open-install";
+/** Fired by the inline head script when Chrome offers an install prompt. */
+export const INSTALL_PROMPT_EVENT = "freezmo:installprompt";
+/** Fired by the inline head script when the app gets installed. */
+export const INSTALLED_EVENT = "freezmo:installed";
+
+/**
+ * iPhone/iPad (including iPadOS 13+, which reports itself as a Mac — a Mac
+ * with more than one touch point is really an iPad) or Android. Everything
+ * else is desktop/unknown and never sees the prompt.
+ */
+export function detectPlatform(
+  ua: string = typeof navigator === "undefined" ? "" : navigator.userAgent,
+  maxTouchPoints: number = typeof navigator === "undefined" ? 0 : navigator.maxTouchPoints || 0,
+): InstallPlatform {
+  if (/iPhone|iPad|iPod/i.test(ua)) return "ios";
+  if (/Macintosh/i.test(ua) && maxTouchPoints > 1) return "ios";
+  if (/Android/i.test(ua)) return "android";
+  return "other";
+}
+
+/** Embedded webviews (Instagram, Facebook, …) can't install anything. */
+const IN_APP_PATTERN =
+  /(FBAN|FBAV|FB_IAB|Instagram|Line\/|Twitter|TikTok|SnapChat|Pinterest|MicroMessenger|GSA\/|; wv\))/i;
+
+/**
+ * Which browser is this? Used to adapt step 1 of the instructions:
+ * iOS outside Safari (and Android outside Chrome) has to switch browsers
+ * first, and in-app browsers can't install at all.
+ */
+export function detectBrowser(
+  platform: InstallPlatform,
+  ua: string = typeof navigator === "undefined" ? "" : navigator.userAgent,
+): InstallBrowser {
+  if (IN_APP_PATTERN.test(ua)) return "in-app";
+  if (platform === "ios") {
+    const otherIos = /(CriOS|FxiOS|EdgiOS|OPiOS|DuckDuckGo)/.test(ua);
+    return /Safari\//.test(ua) && !otherIos ? "safari" : "other";
+  }
+  if (platform === "android") {
+    const otherAndroid = /(SamsungBrowser|OPR\/|Firefox|EdgA|DuckDuckGo|YaBrowser|Vivaldi)/.test(ua);
+    return /Chrome\//.test(ua) && !otherAndroid ? "chrome" : "other";
+  }
+  return "other";
+}
+
+/** True when the app is already running from the home screen / app switcher. */
+export function isStandalone(): boolean {
+  if (typeof window === "undefined") return false;
+  try {
+    const displayMode = window.matchMedia("(display-mode: standalone)").matches;
+    const iosStandalone =
+      (window.navigator as Navigator & { standalone?: boolean }).standalone === true;
+    return displayMode || iosStandalone;
+  } catch {
+    return false;
+  }
+}
+
+export function markInstalled(): void {
+  try {
+    window.localStorage.setItem(INSTALLED_KEY, "1");
+  } catch {
+    /* private mode */
+  }
+}
+
+export function isMarkedInstalled(): boolean {
+  try {
+    return window.localStorage.getItem(INSTALLED_KEY) === "1";
+  } catch {
+    return false;
+  }
+}
+
+/** Installed now, or recorded as installed earlier in this browser. */
+export function isInstalled(): boolean {
+  return isStandalone() || isMarkedInstalled();
+}
+
+/** True while a previous dismissal is still within its 7-day window. */
+export function isDismissed(now: number = Date.now()): boolean {
+  try {
+    const raw = window.localStorage.getItem(DISMISS_KEY);
+    if (!raw) return false;
+    const at = Number.parseInt(raw, 10);
+    return Number.isFinite(at) && now - at < INSTALL_REMIND_MS;
+  } catch {
+    return false;
+  }
+}
+
+export function dismissInstallPrompt(now: number = Date.now()): void {
+  try {
+    window.localStorage.setItem(DISMISS_KEY, String(now));
+  } catch {
+    /* private mode */
+  }
+}
+
+/** Opens the sheet manually (used by the Settings row). */
+export function openInstallSheet(): void {
+  if (typeof window === "undefined") return;
+  window.dispatchEvent(new CustomEvent(OPEN_INSTALL_EVENT));
+}
+
+/**
+ * The sheet follows the app's *explicit* theme choice: dark unless the user
+ * picked light in the app (a system preference alone doesn't count).
+ */
+export function installSheetTheme(): "dark" | "light" {
+  try {
+    return window.localStorage.getItem(THEME_KEY) === "light" ? "light" : "dark";
+  } catch {
+    return "dark";
+  }
+}
+
+/**
+ * Settings helper: is the "Install app" row relevant here? (Mobile platform
+ * and not installed yet.) Starts false so server rendering never mismatches.
+ */
+export function useInstallAvailable(): boolean {
+  const [available, setAvailable] = useState(false);
+  useEffect(() => {
+    setAvailable(detectPlatform() !== "other" && !isInstalled());
+  }, []);
+  return available;
+}