feat(android): pass-the-app card (QR + share sheet + NFC tag)

About page renders ShareAppCard on Android only: a QR of the Zapstore listing,
a share-sheet button for the install link, and NfcWriteButton to write it to a
tag. Single-sourced APP_INSTALL_URL in lib/platform.ts (also used by the About
download button). No peer-to-peer APK transfer (needs native Wi-Fi Direct/BLE +
PackageInstaller + device QA); Zapstore handles install/update.

AGENTS.md

@@ -1537,6 +1537,14 @@ session with **no other memory of this project**. So:
     auto-opened welcome modal. ⚠️ `SignupDialog` is a **default-only** export, so
     lazy-load it as
     `lazy(() => import('…/SignupDialog'))`.
+  - **Pass the app on — Android only (2026-10-26):** the About page renders
+    `ShareAppCard` when `getPlatform() === 'android'` (APK/Zapstore; hidden on
+    web/iOS): a **QR of the Zapstore listing** (`APP_INSTALL_URL` in
+    `lib/platform.ts`, single-sourced), a **share-sheet** button (Nearby
+    Share/SMS/etc.), and `NfcWriteButton` to write the install URL to an NFC tag.
+    ⚠️ Deliberately **no peer-to-peer APK transfer** — that needs native Wi‑Fi
+    Direct/BLE + a `PackageInstaller` flow and real-device QA; Zapstore handles
+    installs/updates. (Not visually verified on-device yet.)
   - **First-run checklist + backup-reminder gating (fixed 2026-10-12).** Two
     onboarding prompts nagged returning users:
     1. `FirstRunChecklist` (map) showed for **any logged-in user** until they

src/components/ShareAppCard.tsx

@@ -0,0 +1,78 @@
+import { useState } from 'react';
+import { Check, Share2 } from 'lucide-react';
+import { Card, CardContent } from '@/components/ui/card';
+import { Button } from '@/components/ui/button';
+import { QRCodeCanvas } from '@/components/ui/qrcode';
+import { NfcWriteButton } from '@/components/NfcWriteButton';
+import { useTranslation } from '@/contexts/language';
+import { useToast } from '@/hooks/useToast';
+import { APP_INSTALL_URL, getPlatform } from '@/lib/platform';
+
+/**
+ * "Pass the app on" — Android only (APK / Zapstore).
+ *
+ * The QR carries the **Zapstore listing** for this app; scanning it on another
+ * Android phone opens the store page and installs/updates via Zapstore. The
+ * share button hands the same link to Android's share sheet (Nearby Share,
+ * Bluetooth, messages…), and — where the device supports NFC writing — the link
+ * can be written to a tag for a genuine tap-to-open handoff.
+ *
+ * We deliberately do NOT move APK bytes peer-to-peer: that needs native
+ * Wi‑Fi Direct/BLE + a PackageInstaller flow and real-device QA, and Zapstore
+ * already handles installs/updates. Renders nothing off Android (iOS can't
+ * sideload; desktop has no use for it).
+ */
+export function ShareAppCard() {
+  const { t } = useTranslation();
+  const { toast } = useToast();
+  const [copied, setCopied] = useState(false);
+
+  if (getPlatform() !== 'android') return null;
+
+  const share = async () => {
+    try {
+      if (navigator.share) {
+        await navigator.share({
+          title: 'SkateSpots',
+          text: t('settingsUi.about.downloadAppDesc'),
+          url: APP_INSTALL_URL,
+        });
+        return;
+      }
+      await navigator.clipboard.writeText(APP_INSTALL_URL);
+      setCopied(true);
+      toast({ title: t('common.copied'), description: APP_INSTALL_URL });
+      window.setTimeout(() => setCopied(false), 1600);
+    } catch {
+      // Share sheet cancelled — nothing to report.
+    }
+  };
+
+  return (
+    <Card className="bg-black/90 border border-white/10 mt-4">
+      <CardContent className="space-y-3 p-5">
+        <div className="space-y-1 text-center">
+          <p className="text-xs font-black uppercase tracking-widest text-gray-300">
+            {t('common.share')} SkateSpots
+          </p>
+          <p className="text-xs text-gray-500">{t('settingsUi.about.downloadAppDesc')}</p>
+        </div>
+
+        <div className="mx-auto w-fit rounded-xl bg-white p-3">
+          <QRCodeCanvas value={APP_INSTALL_URL} size={180} level="M" />
+        </div>
+
+        <Button
+          className="w-full gap-2 bg-[#ccff00] font-bold text-black hover:bg-[#ccff00]/90"
+          onClick={() => void share()}
+        >
+          {copied ? <Check className="h-4 w-4" /> : <Share2 className="h-4 w-4" />}
+          {copied ? t('common.copied') : t('common.share')}
+        </Button>
+
+        {/* Tap-to-open: write the install link to an NFC tag (no-op where unsupported). */}
+        <NfcWriteButton url={APP_INSTALL_URL} />
+      </CardContent>
+    </Card>
+  );
+}

src/lib/platform.ts

@@ -27,6 +27,9 @@ export function getPlatform(): string {
   }
 }
 
+/** Canonical Zapstore listing for this app (install + updates). Android only. */
+export const APP_INSTALL_URL = 'https://zapstore.dev/apps/org.skatespots.app';
+
 /**
  * SkateSpots platform Lightning address. Receives Sasquatch Pro passes AND
  * marketplace listing fees — the same address, deliberately. Single source of

src/pages/AboutPage.tsx

@@ -2,6 +2,8 @@ import { useSeoMeta } from '@unhead/react';
 import { Link } from 'react-router-dom';
 import { Card, CardContent } from '@/components/ui/card';
 import { Button } from '@/components/ui/button';
+import { ShareAppCard } from '@/components/ShareAppCard';
+import { APP_INSTALL_URL } from '@/lib/platform';
 import { useCurrentUser } from '@/hooks/useCurrentUser';
 import { useToast } from '@/hooks/useToast';
 import {
@@ -233,7 +235,7 @@ Version: v0.1.0`;
                 </p>
               </div>
               <a
-                href="https://zapstore.dev/apps/org.skatespots.app"
+                href={APP_INSTALL_URL}
                 target="_blank"
                 rel="noopener noreferrer"
                 className="flex-shrink-0"
@@ -247,6 +249,9 @@ Version: v0.1.0`;
           </CardContent>
         </Card>
 
+        {/* Pass the app on (Android only) — QR / share sheet / NFC tag. */}
+        <ShareAppCard />
+
         {/* Credits */}
         <Card className="bg-black/90 border-2 border-gray-700 mt-8">
           <CardContent className="p-6">