Implement structured Android entry viewer (#99)

crates/storage/tests/presentation.rs

@@ -139,6 +139,32 @@ fn clipboard_races_and_cancellation_never_overwrite_newer_user_content() -> Test
     Ok(())
 }
 
+#[test]
+fn clearing_clipboard_never_reads_or_restores_previous_secrets() -> TestResult {
+    let backend = MemoryClipboard::with_text(b"previous secret");
+    let mut manager = ClipboardManager::new(backend.clone(), ClipboardTimeout::default());
+    let secret = SecretBytes::new(b"copied secret".to_vec());
+    assert_eq!(
+        manager.copy_clearing_with(&secret, |_| ClipboardWait::Elapsed)?,
+        ClipboardDisposition::Cleared
+    );
+    assert_eq!(backend.text(), None);
+    assert_eq!(
+        manager.copy_clearing_with(&secret, |_| {
+            backend.set_text(b"newer value");
+            ClipboardWait::Elapsed
+        })?,
+        ClipboardDisposition::PreservedNewer
+    );
+    assert_eq!(backend.text().as_deref(), Some(b"newer value".as_slice()));
+    assert_eq!(
+        manager.copy_clearing_with(&secret, |_| ClipboardWait::Cancelled),
+        Err(ClipboardError::Cancelled)
+    );
+    assert_eq!(backend.text(), None);
+    Ok(())
+}
+
 #[test]
 fn clipboard_validation_and_cleanup_failures_are_typed_and_redacted() -> TestResult {
     assert_eq!(