Fix Amber login for ZapStore/Capacitor app

- LoginDialog now uses openAmberForLogin() which sends the proper
  intent:// URL with a callbackUrl instead of the old nostrsigner:
  scheme that only copies to clipboard (broken on most setups)
- Add polling loop (500ms, 3min timeout) for amber_pending_pubkey
  written by AmberCallbackPage — works even when Amber opens the
  callback in a new browser tab (GrapheneOS/Android behaviour)
- visibilitychange listener now waits for app to regain focus before
  attempting clipboard read, fixing race condition
- DeepLinkHandler pre-captures ?event= param into sessionStorage
  when Amber fires appUrlOpen deep link in Capacitor, so
  AmberCallbackPage can always find the result
- Add 'paste' to amberStep union type (was missing, caused TS error)

Co-authored-by: shakespeare.diy <assistant@shakespeare.diy>

src/components/DeepLinkHandler.tsx

@@ -45,6 +45,16 @@ export function DeepLinkHandler() {
     AppPlugin.addListener('appUrlOpen', (event) => {
       try {
         const url = new URL(event.url);
+        // Pre-capture Amber callback event param into sessionStorage so
+        // AmberCallbackPage can find it after React Router renders the route.
+        const eventParam = url.searchParams.get('event');
+        if (eventParam) {
+          try {
+            sessionStorage.setItem('amber_callback_event', eventParam);
+            sessionStorage.setItem('amber_callback_url', event.url);
+            sessionStorage.setItem('amber_callback_timestamp', Date.now().toString());
+          } catch { /* ignore storage errors */ }
+        }
         // Extract path + query + fragment from the deep link URL
         const path = url.pathname + url.search + url.hash;
         if (path && path !== '/') {

src/components/auth/LoginDialog.tsx

@@ -2,6 +2,11 @@
 // It is important that all functionality in this file is preserved, and should only be modified if explicitly requested.
 
 import React, { useState, useEffect } from 'react';
+
+// Extend window with a cleanup ref for Amber visibilitychange listener
+declare global {
+  interface Window { __amberUnsubRef?: () => void; }
+}
 import { Shield, UserPlus, Sparkles, Cloud, Smartphone, Check, Loader2, KeyRound } from 'lucide-react';
 import { Button } from '@/components/ui/button';
 import { Input } from '@/components/ui/input';
@@ -10,6 +15,7 @@ import { Tabs, TabsContent, TabsList, TabsTrigger } from '@/components/ui/tabs';
 import { useLoginActions } from '@/hooks/useLoginActions';
 import { useToast } from '@/hooks/useToast';
 import { cn } from '@/lib/utils';
+import { openAmberForLogin, subscribeToAmberReturn } from '@/lib/amber';
 
 
 interface LoginDialogProps {
@@ -27,7 +33,7 @@ export const LoginDialog: React.FC<LoginDialogProps> = ({ isOpen, onClose, onLog
   const [nsecError, setNsecError] = useState('');
 
   // Amber NIP-55 state
-  const [amberStep, setAmberStep] = useState<'idle' | 'loading' | 'done' | 'error'>('idle');
+  const [amberStep, setAmberStep] = useState<'idle' | 'loading' | 'paste' | 'done' | 'error'>('idle');
   const [amberError, setAmberError] = useState('');
 
   const login = useLoginActions();
@@ -35,43 +41,91 @@ export const LoginDialog: React.FC<LoginDialogProps> = ({ isOpen, onClose, onLog
 
   const isAndroid = /Android/i.test(navigator.userAgent);
 
-  // Step 1: open Amber with no callbackUrl → Amber copies pubkey to clipboard
-  // This is confirmed correct from Amber's IntentUtils.kt source:
-  //   - Strips "nostrsigner:" prefix
-  //   - URLDecodes the rest  
-  //   - Parses ?type=get_public_key&... query params
-  //   - No callbackUrl → copies result to clipboard
+  // Detect if running inside a Capacitor native app
+  const isCapacitor = !!(window as unknown as { Capacitor?: { isNativePlatform?: () => boolean } }).Capacitor?.isNativePlatform?.();
+
+  // Step 1: open Amber via proper intent:// URL with a callbackUrl so Amber
+  // redirects back to the app after approval (works in both web PWA and Capacitor APK).
+  // openAmberForLogin() handles building the correct intent: URL with the callback.
   const handleAmberLogin = () => {
     setAmberStep('loading');
-    // Exact format from Amber source: nostrsigner:?type=X&compressionType=none&returnType=signature
-    // No callbackUrl = Amber copies pubkey to clipboard
-    window.location.href = 'nostrsigner:?type=get_public_key&compressionType=none&returnType=signature';
-    // After navigation, app will lose focus. When user comes back, visibilitychange fires.
-    setTimeout(() => setAmberStep('paste'), 500);
+    // Store return path before navigating away
+    const currentPath = window.location.hash.replace(/^#/, '') || '/';
+    localStorage.setItem('amber_return_path', currentPath);
+    // On Capacitor the deep-link fires appUrlOpen, not a page redirect, so we
+    // also need to poll localStorage for the pubkey written by AmberCallbackPage.
+    if (isCapacitor) {
+      // Listen for when app regains focus — Amber will have fired the deep link
+      const unsub = subscribeToAmberReturn(() => {
+        // Give DeepLinkHandler 300 ms to process the URL and write to localStorage
+        setTimeout(checkAmberPendingPubkey, 300);
+      });
+      // Store unsub so we can clean up (store in ref-like closure)
+      window.__amberUnsubRef = unsub;
+    }
+    openAmberForLogin();
+    // Fallback: if somehow we stay on the same page (no redirect happened),
+    // switch to the manual paste step after the dialog loses/regains focus.
+    if (!isCapacitor) {
+      const unsub = subscribeToAmberReturn(() => {
+        checkAmberPendingPubkey();
+      });
+      window.__amberUnsubRef = unsub;
+    }
   };
 
-  // Step 2: when app regains focus, try clipboard auto-read first
-  useEffect(() => {
-    if (amberStep !== 'paste') return;
-    const tryClipboard = async () => {
-      try {
-        const text = (await navigator.clipboard.readText()).trim();
-        // Amber returns hex pubkey OR npub — handle both
-        if (/^[0-9a-f]{64}$/i.test(text)) {
-          completeAmberLogin(text.toLowerCase());
+  // Check if AmberCallbackPage already wrote a pubkey to localStorage
+  // (happens when Amber opens the callback in a new browser tab on Android)
+  const checkAmberPendingPubkey = () => {
+    const storedPubkey = localStorage.getItem('amber_pending_pubkey');
+    if (storedPubkey && /^[0-9a-f]{64}$/i.test(storedPubkey)) {
+      localStorage.removeItem('amber_pending_pubkey');
+      completeAmberLogin(storedPubkey.toLowerCase());
+      return;
+    }
+    // Also try clipboard as fallback
+    tryClipboardForPubkey();
+  };
+
+  // Try reading the pubkey from clipboard (Amber may have copied it there)
+  const tryClipboardForPubkey = async () => {
+    try {
+      const text = (await navigator.clipboard.readText()).trim();
+      if (/^[0-9a-f]{64}$/i.test(text)) {
+        completeAmberLogin(text.toLowerCase());
+        return;
+      }
+      if (text.startsWith('npub1')) {
+        const { nip19 } = await import('nostr-tools');
+        const decoded = nip19.decode(text);
+        if (decoded.type === 'npub') {
+          completeAmberLogin(decoded.data as string);
           return;
         }
-        if (text.startsWith('npub1')) {
-          const { nip19 } = await import('nostr-tools');
-          const decoded = nip19.decode(text);
-          if (decoded.type === 'npub') {
-            completeAmberLogin(decoded.data as string);
-            return;
-          }
-        }
-      } catch { /* clipboard denied — user will paste manually */ }
-    };
-    tryClipboard();
+      }
+    } catch { /* clipboard denied — fall through to manual paste */ }
+    // Couldn't auto-detect — show the manual paste UI
+    setAmberStep('paste');
+  };
+
+  // Poll for amber_pending_pubkey (written by AmberCallbackPage in a separate tab)
+  useEffect(() => {
+    if (amberStep !== 'loading') return;
+    const interval = setInterval(() => {
+      const storedPubkey = localStorage.getItem('amber_pending_pubkey');
+      if (storedPubkey && /^[0-9a-f]{64}$/i.test(storedPubkey)) {
+        localStorage.removeItem('amber_pending_pubkey');
+        clearInterval(interval);
+        completeAmberLogin(storedPubkey.toLowerCase());
+      }
+    }, 500);
+    // Stop polling after 3 minutes
+    const timeout = setTimeout(() => {
+      clearInterval(interval);
+      if (amberStep === 'loading') setAmberStep('paste');
+    }, 180_000);
+    return () => { clearInterval(interval); clearTimeout(timeout); };
+  // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [amberStep]);
 
   const completeAmberLogin = (pubkey: string) => {
@@ -114,6 +168,9 @@ export const LoginDialog: React.FC<LoginDialogProps> = ({ isOpen, onClose, onLog
   // Reset when dialog closes
   useEffect(() => {
     if (!isOpen) {
+      // Clean up any pending Amber visibilitychange listener
+      window.__amberUnsubRef?.();
+      window.__amberUnsubRef = undefined;
       setAmberStep('idle');
       setAmberError('');
       setPubkeyInput('');