Fix key download on Android: save to Documents instead of share sheet

src/components/InitialSyncGate.tsx

@@ -1,3 +1,4 @@
+import { Capacitor } from "@capacitor/core";
 import type { NostrEvent, NostrMetadata } from "@nostrify/nostrify";
 import { useNostr } from "@nostrify/react";
 import { useQueryClient } from "@tanstack/react-query";
@@ -279,6 +280,11 @@ function SetupQuestionnaire({
 
       await downloadTextFile(filename, nsec);
 
+      // Let the user know where the file ended up on Android
+      if (Capacitor.getPlatform() === "android") {
+        toast({ title: "Key saved", description: `Saved to Documents/${filename}` });
+      }
+
       // Log in with the new key
       login.nsec(nsec);
       next();

src/components/auth/SignupDialog.tsx

@@ -1,6 +1,7 @@
 // NOTE: This file is stable and usually should not be modified.
 // It is important that all functionality in this file is preserved, and should only be modified if explicitly requested.
 
+import { Capacitor } from '@capacitor/core';
 import React, { useState, useEffect, useRef } from 'react';
 import { Download, Eye, EyeOff, Loader2 } from 'lucide-react';
 import { Button } from '@/components/ui/button';
@@ -58,6 +59,10 @@ const SignupDialog: React.FC<SignupDialogProps> = ({ isOpen, onClose }) => {
 
       await downloadTextFile(filename, nsec);
 
+      if (Capacitor.getPlatform() === 'android') {
+        toast({ title: 'Key saved', description: `Saved to Documents/${filename}` });
+      }
+
       // Continue to profile step
       login.nsec(nsec);
       setStep('profile');

src/lib/downloadFile.ts

@@ -4,27 +4,41 @@ import { Capacitor } from '@capacitor/core';
  * Download a text file to the user's device.
  *
  * On the web this uses the classic `<a download>` trick.
- * On native (Capacitor iOS/Android) this writes to a temp file via
- * the Filesystem plugin and presents the native share sheet so the
- * user can save / AirDrop / share the file.
+ * On Android it writes directly to the app-scoped Documents directory
+ * (no extra permissions needed on Android 11+).
+ * On iOS it writes to a temp file and presents the native share sheet.
  */
 export async function downloadTextFile(filename: string, content: string): Promise<void> {
-  if (Capacitor.isNativePlatform()) {
+  const platform = Capacitor.getPlatform();
+
+  if (platform === 'android') {
+    const { Filesystem, Directory } = await import('@capacitor/filesystem');
+
+    // Write directly to the Documents directory. On Android 11+ the app can
+    // write to its own scoped area inside public Documents without needing
+    // WRITE_EXTERNAL_STORAGE permission.
+    await Filesystem.writeFile({
+      path: filename,
+      data: content,
+      directory: Directory.Documents,
+    });
+  } else if (platform === 'ios') {
     const { Filesystem, Directory } = await import('@capacitor/filesystem');
     const { Share } = await import('@capacitor/share');
 
-    // Write to the cache directory (always writable, no permissions needed)
     const result = await Filesystem.writeFile({
       path: filename,
       data: content,
       directory: Directory.Cache,
     });
 
-    // Present the native share sheet so the user can save / share the file
-    await Share.share({
-      title: filename,
-      url: result.uri,
-    });
+    // On iOS there is no user-visible Downloads folder, so present the
+    // share sheet and let the user choose where to save / send the file.
+    try {
+      await Share.share({ title: filename, url: result.uri });
+    } catch {
+      // User dismissed the share sheet — not a real failure
+    }
   } else {
     // Web: use the anchor-click download pattern
     const blob = new Blob([content], { type: 'text/plain; charset=utf-8' });