Merge pull request #27 from sudosylabs/fix/typed-error-propagation

fix(core): preserve typed transfer failures

apple/Tests/UiFeedbackTests.swift

@@ -1,4 +1,5 @@
 import XCTest
+import VnidropCore
 @testable import VniDrop
 
 /// Ports `ui/feedback/UiMessageControllerTest.kt` and `UserFacingErrorTest.kt`.
@@ -50,4 +51,15 @@ final class UserFacingErrorTests: XCTestCase {
 	func testToUiTextFallsBackToGeneric() {
 		XCTAssertEqual(InvitationError.message("something entirely unexpected").toUiText(), .resource("error_generic"))
 	}
+
+	func testToUiTextMapsTypedTransferFailures() {
+		XCTAssertEqual(VnidropError.FilesystemPermission(reason: "read-only folder").toUiText(), .resource("error_filesystem"))
+		XCTAssertEqual(VnidropError.DestinationExists(reason: "target exists").toUiText(), .resource("error_destination_exists"))
+		XCTAssertEqual(VnidropError.StorageFull(reason: "disk full").toUiText(), .resource("error_storage_full"))
+		XCTAssertEqual(VnidropError.Network(reason: "offline").toUiText(), .resource("error_network"))
+		XCTAssertEqual(VnidropError.InvalidInput(reason: "bad path").toUiText(), .resource("error_invalid_input"))
+		XCTAssertFalse(VnidropError.FilesystemPermission(reason: "read-only").canRetryWithoutChangingInput)
+		XCTAssertFalse(VnidropError.DestinationExists(reason: "target exists").canRetryWithoutChangingInput)
+		XCTAssertTrue(VnidropError.Network(reason: "offline").canRetryWithoutChangingInput)
+	}
 }

apple/VniDrop/Features/Receive/ReceiveModel.swift

@@ -192,8 +192,8 @@ final class ReceiveModel: ObservableObject {
 				messages.tryShow(UiMessage(
 					text: uiText,
 					tone: .error,
-					actionLabel: .resource("button_retry"),
+					actionLabel: error.canRetryWithoutChangingInput ? .resource("button_retry") : nil,
-					onAction: { self.receive() }
+					onAction: error.canRetryWithoutChangingInput ? { self.receive() } : nil
 				))
 			}
 		}

apple/VniDrop/Resources/Localizable.xcstrings

@@ -5109,6 +5109,66 @@
         }
       }
     },
+    "error_destination_exists": {
+      "comment": "Error: a received file would overwrite an existing destination file.",
+      "extractionState": "manual",
+      "localizations": {
+        "de": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "Am Ziel ist bereits eine Datei mit demselben Namen vorhanden. Wählen Sie einen anderen Ordner oder entfernen Sie die vorhandene Datei."
+          }
+        },
+        "en": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "A file with the same name already exists in the destination. Choose another folder or remove the existing file."
+          }
+        },
+        "es": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "Ya existe un archivo con el mismo nombre en el destino. Elija otra carpeta o elimine el archivo existente."
+          }
+        },
+        "fr": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "Un fichier portant le même nom existe déjà dans la destination. Choisissez un autre dossier ou supprimez le fichier existant."
+          }
+        },
+        "it": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "Nella destinazione esiste già un file con lo stesso nome. Scelga un’altra cartella o rimuova il file esistente."
+          }
+        },
+        "nl": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "Er staat al een bestand met dezelfde naam in de doelmap. Kies een andere map of verwijder het bestaande bestand."
+          }
+        },
+        "pl": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "W miejscu docelowym istnieje już plik o tej samej nazwie. Wybierz inny folder lub usuń istniejący plik."
+          }
+        },
+        "pt": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "Já existe um ficheiro com o mesmo nome no destino. Escolha outra pasta ou remova o ficheiro existente."
+          }
+        },
+        "ru": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "В папке назначения уже есть файл с таким именем. Выберите другую папку или удалите существующий файл."
+          }
+        }
+      }
+    },
     "error_device_info": {
       "comment": "Error: device information could not be loaded.",
       "extractionState": "manual",
@@ -5349,6 +5409,66 @@
         }
       }
     },
+    "error_invalid_input": {
+      "comment": "Error: transfer input or metadata is invalid.",
+      "extractionState": "manual",
+      "localizations": {
+        "de": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "Einige Übertragungsinformationen sind ungültig. Prüfen Sie Ihre Auswahl oder bitten Sie den Absender, erneut zu teilen."
+          }
+        },
+        "en": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "Some transfer information is invalid. Review your selection or ask the sender to share again."
+          }
+        },
+        "es": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "Parte de la información de la transferencia no es válida. Revise la selección o pida al remitente que vuelva a compartirla."
+          }
+        },
+        "fr": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "Certaines informations du transfert ne sont pas valides. Vérifiez votre sélection ou demandez à l’expéditeur de partager à nouveau."
+          }
+        },
+        "it": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "Alcune informazioni del trasferimento non sono valide. Controlli la selezione o chieda al mittente di condividere di nuovo."
+          }
+        },
+        "nl": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "Sommige overdrachtsgegevens zijn ongeldig. Controleer uw selectie of vraag de afzender opnieuw te delen."
+          }
+        },
+        "pl": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "Niektóre informacje o transferze są nieprawidłowe. Sprawdź wybór lub poproś nadawcę o ponowne udostępnienie."
+          }
+        },
+        "pt": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "Algumas informações da transferência são inválidas. Reveja a seleção ou peça ao remetente para partilhar novamente."
+          }
+        },
+        "ru": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "Некоторые данные передачи недействительны. Проверьте выбор или попросите отправителя поделиться снова."
+          }
+        }
+      }
+    },
     "error_invalid_ticket": {
       "comment": "Error: the invitation/ticket could not be parsed.",
       "extractionState": "manual",
@@ -5529,6 +5649,66 @@
         }
       }
     },
+    "error_network": {
+      "comment": "Error: the sender could not be reached over the local network.",
+      "extractionState": "manual",
+      "localizations": {
+        "de": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "VniDrop konnte den Absender nicht erreichen. Prüfen Sie die Verbindung auf beiden Geräten und versuchen Sie es erneut."
+          }
+        },
+        "en": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "VniDrop could not reach the sender. Check the connection on both devices and try again."
+          }
+        },
+        "es": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "VniDrop no pudo contactar con el remitente. Compruebe la conexión en ambos dispositivos e inténtelo de nuevo."
+          }
+        },
+        "fr": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "VniDrop n’a pas pu joindre l’expéditeur. Vérifiez la connexion sur les deux appareils et réessayez."
+          }
+        },
+        "it": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "VniDrop non è riuscito a raggiungere il mittente. Controlli la connessione su entrambi i dispositivi e riprovi."
+          }
+        },
+        "nl": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "VniDrop kon de afzender niet bereiken. Controleer de verbinding op beide apparaten en probeer het opnieuw."
+          }
+        },
+        "pl": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "VniDrop nie mógł połączyć się z nadawcą. Sprawdź połączenie na obu urządzeniach i spróbuj ponownie."
+          }
+        },
+        "pt": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "O VniDrop não conseguiu contactar o remetente. Verifique a ligação nos dois dispositivos e tente novamente."
+          }
+        },
+        "ru": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "VniDrop не удалось связаться с отправителем. Проверьте подключение на обоих устройствах и повторите попытку."
+          }
+        }
+      }
+    },
     "error_nfc": {
       "comment": "Error: the NFC tag could not be read/used.",
       "extractionState": "manual",
@@ -5949,62 +6129,122 @@
         }
       }
     },
-    "error_transfer": {
+    "error_storage_full": {
-      "comment": "Error: the transfer could not be completed.",
+      "comment": "Error: the destination does not have enough free storage.",
       "extractionState": "manual",
       "localizations": {
         "de": {
           "stringUnit": {
             "state": "needs_review",
-            "value": "Die Übertragung konnte nicht abgeschlossen werden. Überprüfen Sie Ihre Verbindung und versuchen Sie es erneut."
+            "value": "Zum Speichern dieser Übertragung ist nicht genügend Speicherplatz vorhanden. Geben Sie Speicherplatz frei und versuchen Sie es erneut."
           }
         },
         "en": {
           "stringUnit": {
             "state": "translated",
-            "value": "The transfer could not be completed. Check your connection and try again."
+            "value": "There is not enough storage space to save this transfer. Free up space and try again."
           }
         },
         "es": {
           "stringUnit": {
             "state": "needs_review",
-            "value": "No se pudo completar la transferencia. Compruebe su conexión e inténtelo de nuevo."
+            "value": "No hay suficiente espacio de almacenamiento para guardar esta transferencia. Libere espacio e inténtelo de nuevo."
           }
         },
         "fr": {
           "stringUnit": {
             "state": "needs_review",
-            "value": "Le transfert n’a pas pu être terminé. Vérifiez votre connexion et réessayez."
+            "value": "L’espace de stockage est insuffisant pour enregistrer ce transfert. Libérez de l’espace et réessayez."
           }
         },
         "it": {
           "stringUnit": {
             "state": "needs_review",
-            "value": "Impossibile completare il trasferimento. Controlli la connessione e riprovi."
+            "value": "Lo spazio di archiviazione non è sufficiente per salvare il trasferimento. Liberi spazio e riprovi."
           }
         },
         "nl": {
           "stringUnit": {
             "state": "needs_review",
-            "value": "De overdracht kon niet worden voltooid. Controleer uw verbinding en probeer het opnieuw."
+            "value": "Er is onvoldoende opslagruimte om deze overdracht op te slaan. Maak ruimte vrij en probeer het opnieuw."
           }
         },
         "pl": {
           "stringUnit": {
             "state": "needs_review",
-            "value": "Nie udało się ukończyć transferu. Sprawdź połączenie i spróbuj ponownie."
+            "value": "Brakuje miejsca na zapisanie tego transferu. Zwolnij miejsce i spróbuj ponownie."
           }
         },
         "pt": {
           "stringUnit": {
             "state": "needs_review",
-            "value": "Não foi possível concluir a transferência. Verifique a sua ligação e tente novamente."
+            "value": "Não existe espaço de armazenamento suficiente para guardar esta transferência. Liberte espaço e tente novamente."
           }
         },
         "ru": {
           "stringUnit": {
             "state": "needs_review",
-            "value": "Не удалось завершить передачу. Проверьте подключение и повторите попытку."
+            "value": "Недостаточно места для сохранения этой передачи. Освободите место и повторите попытку."
+          }
+        }
+      }
+    },
+    "error_transfer": {
+      "comment": "Error: transfer data could not be processed; network failures use error_network.",
+      "extractionState": "manual",
+      "localizations": {
+        "de": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "Die Übertragungsdaten konnten nicht verarbeitet werden. Bitten Sie den Absender, sie erneut zu teilen."
+          }
+        },
+        "en": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "The transfer data could not be processed. Ask the sender to share it again."
+          }
+        },
+        "es": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "No se pudieron procesar los datos de la transferencia. Pida al remitente que vuelva a compartirlos."
+          }
+        },
+        "fr": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "Les données du transfert n’ont pas pu être traitées. Demandez à l’expéditeur de les partager à nouveau."
+          }
+        },
+        "it": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "Non è stato possibile elaborare i dati del trasferimento. Chieda al mittente di condividerli di nuovo."
+          }
+        },
+        "nl": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "De overdrachtsgegevens konden niet worden verwerkt. Vraag de afzender ze opnieuw te delen."
+          }
+        },
+        "pl": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "Nie udało się przetworzyć danych transferu. Poproś nadawcę o ponowne udostępnienie."
+          }
+        },
+        "pt": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "Não foi possível processar os dados da transferência. Peça ao remetente para os partilhar novamente."
+          }
+        },
+        "ru": {
+          "stringUnit": {
+            "state": "needs_review",
+            "value": "Не удалось обработать данные передачи. Попросите отправителя поделиться ими снова."
           }
         }
       }

apple/VniDrop/UI/Feedback/UserFacingError.swift

@@ -13,10 +13,22 @@ extension Error {
 				return .resource("error_permission")
 			case .Filesystem:
 				return .resource("error_filesystem")
+			case .FilesystemPermission:
+				return .resource("error_filesystem")
+			case .DestinationExists:
+				return .resource("error_destination_exists")
+			case .StorageFull:
+				return .resource("error_storage_full")
+			case .Network:
+				return .resource("error_network")
 			case .Transfer(let reason):
 				return transferUiText(reason)
 			case .Repository:
 				return .resource("error_repository")
+			case .Cancelled:
+				return .resource("error_generic")
+			case .InvalidInput:
+				return .resource("error_invalid_input")
 			case .Initialization(let reason):
 				return initializationUiText(reason)
 			case .Internal(let reason):
@@ -28,6 +40,7 @@ extension Error {
 
 	/// True when the user intentionally backed out of a flow.
 	var isUserCancellation: Bool {
+		if let vni = self as? VnidropError, case .Cancelled = vni { return true }
 		let haystack = technicalDetail.lowercased()
 		if haystack.isEmpty {
 			// URLError / CocoaError cancellation without a message.
@@ -44,13 +57,23 @@ extension Error {
 	var technicalDetail: String {
 		if let vni = self as? VnidropError {
 			switch vni {
-			case .Initialization(let r), .Ticket(let r), .Filesystem(let r),
+			case .Initialization(let r), .Ticket(let r), .Filesystem(let r), .FilesystemPermission(let r),
-				 .Transfer(let r), .Permission(let r), .Repository(let r), .Internal(let r):
+				 .DestinationExists(let r), .StorageFull(let r), .Network(let r),
+				 .Transfer(let r), .Permission(let r), .Repository(let r), .Cancelled(let r),
+				 .InvalidInput(let r), .Internal(let r):
 				return r
 			}
 		}
 		return (self as? LocalizedError)?.errorDescription ?? (self as NSError).localizedDescription
 	}
+
+	var canRetryWithoutChangingInput: Bool {
+		guard let vni = self as? VnidropError else { return true }
+		switch vni {
+		case .FilesystemPermission, .DestinationExists, .InvalidInput: return false
+		default: return true
+		}
+	}
 }
 
 private func transferUiText(_ reason: String) -> UiText {

crates/vnidrop/src/error.rs

@@ -8,12 +8,24 @@ pub enum VnidropError {
     Ticket { reason: String },
     #[error("filesystem error: {reason}")]
     Filesystem { reason: String },
+    #[error("filesystem permission denied: {reason}")]
+    FilesystemPermission { reason: String },
+    #[error("destination already exists: {reason}")]
+    DestinationExists { reason: String },
+    #[error("storage is full: {reason}")]
+    StorageFull { reason: String },
+    #[error("network error: {reason}")]
+    Network { reason: String },
     #[error("transfer error: {reason}")]
     Transfer { reason: String },
     #[error("permission error: {reason}")]
     Permission { reason: String },
     #[error("repository error: {reason}")]
     Repository { reason: String },
+    #[error("operation cancelled: {reason}")]
+    Cancelled { reason: String },
+    #[error("invalid input: {reason}")]
+    InvalidInput { reason: String },
     #[error("internal error: {reason}")]
     Internal { reason: String },
 }
@@ -32,42 +44,138 @@ impl VnidropError {
     }
 
     pub(crate) fn filesystem(error: impl Into<anyhow::Error>) -> Self {
-        Self::Filesystem {
+        let error = error.into();
-            reason: error.into().to_string(),
+        Self::classify(error, |reason| Self::Filesystem { reason })
     }
+
+    pub(crate) fn network(error: impl Into<anyhow::Error>) -> Self {
+        Self::from_error(error.into(), |reason| Self::Network { reason })
     }
 
     pub(crate) fn transfer(error: impl Into<anyhow::Error>) -> Self {
-        Self::Transfer {
+        let error = error.into();
-            reason: error.into().to_string(),
+        Self::classify(error, |reason| Self::Transfer { reason })
-        }
     }
 
     pub(crate) fn permission(error: impl Into<anyhow::Error>) -> Self {
-        Self::Permission {
+        Self::classify(error.into(), |reason| Self::Permission { reason })
-            reason: error.into().to_string(),
-        }
     }
 
     pub(crate) fn repository(error: impl Into<anyhow::Error>) -> Self {
-        Self::Repository {
+        Self::from_error(error.into(), |reason| Self::Repository { reason })
-            reason: error.into().to_string(),
+    }
+
+    pub(crate) fn cancelled(reason: impl Into<String>) -> Self {
+        Self::Cancelled {
+            reason: reason.into(),
+        }
+    }
+
+    pub(crate) fn invalid_input(error: impl Into<anyhow::Error>) -> Self {
+        Self::from_error(error.into(), |reason| Self::InvalidInput { reason })
+    }
+
+    pub(crate) fn internal(error: impl Into<anyhow::Error>) -> Self {
+        Self::from_error(error.into(), |reason| Self::Internal { reason })
+    }
+
+    pub(crate) fn code(&self) -> &'static str {
+        match self {
+            Self::Initialization { .. } => "initialization",
+            Self::Ticket { .. } => "invalid_ticket",
+            Self::Filesystem { .. } => "filesystem",
+            Self::FilesystemPermission { .. } => "filesystem_permission_denied",
+            Self::DestinationExists { .. } => "destination_exists",
+            Self::StorageFull { .. } => "storage_full",
+            Self::Network { .. } => "network",
+            Self::Transfer { .. } => "transfer",
+            Self::Permission { .. } => "permission_denied",
+            Self::Repository { .. } => "repository",
+            Self::Cancelled { .. } => "cancelled",
+            Self::InvalidInput { .. } => "invalid_input",
+            Self::Internal { .. } => "internal",
+        }
+    }
+
+    pub(crate) fn reason(&self) -> &str {
+        match self {
+            Self::Initialization { reason }
+            | Self::Ticket { reason }
+            | Self::Filesystem { reason }
+            | Self::FilesystemPermission { reason }
+            | Self::DestinationExists { reason }
+            | Self::StorageFull { reason }
+            | Self::Network { reason }
+            | Self::Transfer { reason }
+            | Self::Permission { reason }
+            | Self::Repository { reason }
+            | Self::Cancelled { reason }
+            | Self::InvalidInput { reason }
+            | Self::Internal { reason } => reason,
+        }
+    }
+
+    fn classify(error: anyhow::Error, fallback: impl FnOnce(String) -> Self) -> Self {
+        let reason = error.to_string();
+        if let Some(existing) = error.chain().find_map(|cause| cause.downcast_ref::<Self>()) {
+            return existing.with_reason(reason);
+        }
+        if let Some(io_error) = error
+            .chain()
+            .find_map(|cause| cause.downcast_ref::<io::Error>())
+        {
+            return match io_error.kind() {
+                io::ErrorKind::AlreadyExists => Self::DestinationExists { reason },
+                io::ErrorKind::PermissionDenied => Self::FilesystemPermission { reason },
+                io::ErrorKind::StorageFull => Self::StorageFull { reason },
+                _ => Self::Filesystem { reason },
+            };
+        }
+        if error
+            .chain()
+            .any(|cause| cause.downcast_ref::<sqlx::Error>().is_some())
+        {
+            return Self::Repository { reason };
+        }
+        fallback(reason)
+    }
+
+    fn from_error(error: anyhow::Error, fallback: impl FnOnce(String) -> Self) -> Self {
+        let reason = error.to_string();
+        if let Some(existing) = error.chain().find_map(|cause| cause.downcast_ref::<Self>()) {
+            existing.with_reason(reason)
+        } else {
+            fallback(reason)
+        }
+    }
+
+    fn with_reason(&self, reason: String) -> Self {
+        match self {
+            Self::Initialization { .. } => Self::Initialization { reason },
+            Self::Ticket { .. } => Self::Ticket { reason },
+            Self::Filesystem { .. } => Self::Filesystem { reason },
+            Self::FilesystemPermission { .. } => Self::FilesystemPermission { reason },
+            Self::DestinationExists { .. } => Self::DestinationExists { reason },
+            Self::StorageFull { .. } => Self::StorageFull { reason },
+            Self::Network { .. } => Self::Network { reason },
+            Self::Transfer { .. } => Self::Transfer { reason },
+            Self::Permission { .. } => Self::Permission { reason },
+            Self::Repository { .. } => Self::Repository { reason },
+            Self::Cancelled { .. } => Self::Cancelled { reason },
+            Self::InvalidInput { .. } => Self::InvalidInput { reason },
+            Self::Internal { .. } => Self::Internal { reason },
         }
     }
 }
 
 impl From<anyhow::Error> for VnidropError {
     fn from(error: anyhow::Error) -> Self {
-        Self::Internal {
+        Self::classify(error, |reason| Self::Internal { reason })
-            reason: error.to_string(),
-        }
     }
 }
 
 impl From<io::Error> for VnidropError {
     fn from(error: io::Error) -> Self {
-        Self::Filesystem {
+        Self::filesystem(error)
-            reason: error.to_string(),
-        }
     }
 }

crates/vnidrop/src/filesystem.rs

@@ -69,7 +69,11 @@ impl AtomicOutputFile {
         }
         cleanup_stale_temporary_files(parent, STALE_PART_AGE)?;
         if std::fs::symlink_metadata(&target).is_ok() {
-            anyhow::bail!("destination already exists: {}", target.display());
+            return Err(io::Error::new(
+                io::ErrorKind::AlreadyExists,
+                format!("destination already exists: {}", target.display()),
+            )
+            .into());
         }
 
         let final_name = target

crates/vnidrop/src/runtime/receive.rs

@@ -21,6 +21,7 @@ use crate::{
         ReceiveOutputSink, ReceiveOutputSinkV2, ReceivedLocatorKind, TransferAccessMode,
         TransferMetadata,
     },
+    error::VnidropError,
     filesystem::{
         validated_relative_string, wait_for_writer, write_stream_to_blocking_writer,
         AtomicOutputFile,
@@ -52,7 +53,7 @@ pub(super) struct OutputSinkFile<'a> {
 impl<'a> OutputSinkFile<'a> {
     fn start(sink: &'a dyn ReceiveOutputSink, relative_path: String) -> Result<Self> {
         sink.start_file(relative_path.clone())
-            .map_err(|error| anyhow::anyhow!(error.to_string()))?;
+            .map_err(anyhow::Error::new)?;
         Ok(Self {
             sink,
             relative_path,
@@ -63,7 +64,7 @@ impl<'a> OutputSinkFile<'a> {
     fn write(&self, bytes: Vec<u8>) -> Result<()> {
         self.sink
             .write_chunk(self.relative_path.clone(), bytes)
-            .map_err(|error| anyhow::anyhow!(error.to_string()))
+            .map_err(anyhow::Error::new)
     }
 
     fn finish(mut self) -> Result<()> {
@@ -73,7 +74,7 @@ impl<'a> OutputSinkFile<'a> {
         self.terminal = true;
         self.sink
             .finish_file(self.relative_path.clone())
-            .map_err(|error| anyhow::anyhow!(error.to_string()))
+            .map_err(anyhow::Error::new)
     }
 }
 
@@ -104,7 +105,7 @@ pub(super) struct OutputSinkFileV2<'a> {
 impl<'a> OutputSinkFileV2<'a> {
     fn start(sink: &'a dyn ReceiveOutputSinkV2, relative_path: String) -> Result<Self> {
         sink.start_file(relative_path.clone())
-            .map_err(|error| anyhow::anyhow!(error.to_string()))?;
+            .map_err(anyhow::Error::new)?;
         Ok(Self {
             sink,
             relative_path,
@@ -115,14 +116,14 @@ impl<'a> OutputSinkFileV2<'a> {
     fn write(&self, bytes: Vec<u8>) -> Result<()> {
         self.sink
             .write_chunk(self.relative_path.clone(), bytes)
-            .map_err(|error| anyhow::anyhow!(error.to_string()))
+            .map_err(anyhow::Error::new)
     }
 
     fn finish(mut self) -> Result<crate::api::PublishedOutput> {
         self.terminal = true;
         self.sink
             .finish_file(self.relative_path.clone())
-            .map_err(|error| anyhow::anyhow!(error.to_string()))
+            .map_err(anyhow::Error::new)
     }
 }
 
@@ -189,7 +190,8 @@ impl CoreInner {
             .transfer_slots
             .acquire()
             .await
-            .context("transfer limiter is closed")?;
+            .context("transfer limiter is closed")
+            .map_err(VnidropError::internal)?;
         let parsed = match parse_transfer_ticket_with_limits(&ticket, &self.limits)
             .context("failed to parse transfer ticket")
         {
@@ -205,7 +207,8 @@ impl CoreInner {
         };
         let transfer_id = parsed.metadata.transfer_id;
         self.persist_receive_start(transfer_id, &parsed, receiver_name.as_deref())
-            .await?;
+            .await
+            .map_err(VnidropError::repository)?;
         // Cancellation is cooperative: it stops our receive future and marks
         // local state while lower-level Iroh work unwinds naturally.
         let (shutdown_tx, mut shutdown_rx) = oneshot::channel();
@@ -221,8 +224,10 @@ impl CoreInner {
             );
 
         let (result, cancelled) = tokio::select! {
-            result = self.receive_inner(transfer_id, parsed, target, receiver_name) => (result, false),
+            result = self.receive_inner(transfer_id, parsed, target, receiver_name) => {
-            _ = &mut shutdown_rx => (Err(anyhow::anyhow!("transfer cancelled")), true),
+                (result.map_err(VnidropError::transfer), false)
+            },
+            _ = &mut shutdown_rx => (Err(VnidropError::cancelled("transfer cancelled")), true),
         };
 
         self.active_transfers
@@ -238,7 +243,7 @@ impl CoreInner {
                     "receive",
                     "error",
                     "failed",
-                    json!({ "reason": error.to_string() }),
+                    json!({ "code": error.code(), "reason": error.reason() }),
                 );
                 let _ = self
                     .repository
@@ -250,7 +255,7 @@ impl CoreInner {
                     .await;
             }
         }
-        result
+        result.map_err(anyhow::Error::new)
     }
 
     pub(super) async fn receive_inner(
@@ -261,7 +266,9 @@ impl CoreInner {
         receiver_name: Option<String>,
     ) -> Result<()> {
         if let ReceiveTarget::Directory(output_dir) = &target {
-            tokio::fs::create_dir_all(output_dir).await?;
+            tokio::fs::create_dir_all(output_dir)
+                .await
+                .map_err(VnidropError::filesystem)?;
         }
         let sender_addr = parsed.blob_ticket.addr().clone();
 
@@ -278,14 +285,16 @@ impl CoreInner {
         let connection = self
             .endpoint
             .connect(sender_addr.clone(), iroh_blobs::ALPN)
-            .await?;
+            .await
+            .map_err(VnidropError::network)?;
         self.emit_transfer(transfer_id, "receive", "network", "connected", json!({}));
 
         let hash_and_format = parsed.blob_ticket.hash_and_format();
         let (_hash_seq, sizes) =
             get_hash_seq_and_sizes(&connection, &hash_and_format.hash, 1024 * 1024 * 32, None)
                 .await
-                .context("failed to get file sizes")?;
+                .context("failed to get file sizes")
+                .map_err(VnidropError::network)?;
         let total_size = sizes
             .iter()
             .try_fold(0u64, |total, size| total.checked_add(*size))
@@ -331,7 +340,11 @@ impl CoreInner {
                     );
                 }
                 GetProgressItem::Done(_) => break,
-                GetProgressItem::Error(error) => anyhow::bail!("download failed: {error}"),
+                GetProgressItem::Error(error) => {
+                    return Err(
+                        VnidropError::network(anyhow::anyhow!("download failed: {error}")).into(),
+                    );
+                }
             }
         }
 
@@ -344,7 +357,8 @@ impl CoreInner {
                 TransferStatus::Receiving,
                 TransferStatus::Done,
             )
-            .await?;
+            .await
+            .map_err(VnidropError::repository)?;
         drop(download_tag);
         self.emit_transfer(transfer_id, "receive", "lifecycle", "done", json!({}));
         let sender_transfer_id = delivery_receipt.transfer_id;
@@ -395,7 +409,8 @@ impl CoreInner {
                 total_size: parsed.metadata.total_size,
                 access_mode: mode_to_storage(&TransferAccessMode::ApprovalRequired),
             })
-            .await?;
+            .await
+            .map_err(VnidropError::repository)?;
         let metadata_json =
             serde_json::to_value(&parsed.metadata).unwrap_or(serde_json::Value::Null);
         self.emit_transfer(
@@ -433,8 +448,9 @@ impl CoreInner {
         match client
             .request_transfer(metadata, receiver_name)
             .await
-            .map_err(|error| anyhow::anyhow!("handshake request failed: {error}"))?
+            .map_err(|error| {
-        {
+                VnidropError::network(anyhow::anyhow!("handshake request failed: {error}"))
+            })? {
             HandshakeResponse::Approved {
                 request_id,
                 token,
@@ -456,9 +472,10 @@ impl CoreInner {
                     token,
                 })
             }
-            HandshakeResponse::Denied { reason } => {
+            HandshakeResponse::Denied { reason } => Err(VnidropError::permission(anyhow::anyhow!(
-                anyhow::bail!("transfer request was denied by sender: {reason}")
+                "transfer request was denied by sender: {reason}"
-            }
+            ))
+            .into()),
         }
     }
 
@@ -469,7 +486,11 @@ impl CoreInner {
         target: ReceiveTarget,
         collection: Collection,
     ) -> Result<()> {
-        let transfer_local_id = self.repository.transfer_local_id(transfer_id).await?;
+        let transfer_local_id = self
+            .repository
+            .transfer_local_id(transfer_id)
+            .await
+            .map_err(VnidropError::repository)?;
         let received_transfer = ReceivedTransfer {
             protocol_id: transfer_id,
             local_id: &transfer_local_id,
@@ -529,7 +550,8 @@ impl CoreInner {
                 self.limits.max_path_bytes
             );
         }
-        let (pending_file, writer) = AtomicOutputFile::create(output_dir, relative_path)?;
+        let (pending_file, writer) = AtomicOutputFile::create(output_dir, relative_path)
+            .map_err(VnidropError::filesystem)?;
         let (tx, rx) = async_channel::bounded::<io::Result<Option<Bytes>>>(2);
         let writer_task = std::thread::spawn(move || write_stream_to_blocking_writer(writer, rx));
         let mut stream = self.store.export_ranges(hash, 0..u64::MAX).stream();
@@ -572,10 +594,16 @@ impl CoreInner {
         tx.send(Ok(None))
             .await
             .map_err(|_| anyhow::anyhow!("export writer closed for {relative_path}"))?;
-        let writer = wait_for_writer(writer_task).await??;
+        let writer = wait_for_writer(writer_task)
-        tokio::task::spawn_blocking(move || writer.sync_all()).await??;
+            .await
+            .map_err(VnidropError::internal)?
+            .map_err(VnidropError::filesystem)?;
+        tokio::task::spawn_blocking(move || writer.sync_all())
+            .await
+            .map_err(VnidropError::internal)?
+            .map_err(VnidropError::filesystem)?;
         let locator = pending_file.target().to_string_lossy().to_string();
-        pending_file.commit()?;
+        pending_file.commit().map_err(VnidropError::filesystem)?;
         self.repository
             .record_received_artifact(ReceivedArtifactInsert {
                 transfer_local_id: transfer.local_id,
@@ -585,7 +613,8 @@ impl CoreInner {
                 locator: &locator,
                 logical_size: exported,
             })
-            .await?;
+            .await
+            .map_err(VnidropError::repository)?;
         Ok(())
     }
 
@@ -712,7 +741,8 @@ impl CoreInner {
                 locator: &published.locator,
                 logical_size: exported,
             })
-            .await?;
+            .await
+            .map_err(VnidropError::repository)?;
         Ok(())
     }
 }

crates/vnidrop/src/runtime/share.rs

@@ -17,6 +17,7 @@ use crate::{
     access_policy::mode_to_storage,
     api::TransferMetadata,
     api::{ShareMetadataInput, ShareResult, ShareSource},
+    error::VnidropError,
     filesystem::{
         collect_import_files_with_limits, default_collection_name,
         read_stream_from_blocking_reader, TransferImport,
@@ -37,22 +38,29 @@ impl CoreInner {
             .transfer_slots
             .acquire()
             .await
-            .context("transfer limiter is closed")?;
+            .context("transfer limiter is closed")
+            .map_err(VnidropError::internal)?;
         let transfer_id = metadata.transfer_id;
         if sources.is_empty() {
-            anyhow::bail!("at least one source is required");
+            return Err(VnidropError::invalid_input(anyhow::anyhow!(
+                "at least one source is required"
+            ))
+            .into());
         }
         if sources.len() as u64 > self.limits.max_sources {
-            anyhow::bail!(
+            return Err(VnidropError::invalid_input(anyhow::anyhow!(
                 "source count {} exceeds limit {}",
                 sources.len(),
                 self.limits.max_sources
-            );
+            ))
+            .into());
         }
         self.limits
-            .validate_metadata_text("transfer name", metadata.transfer_name.as_deref())?;
+            .validate_metadata_text("transfer name", metadata.transfer_name.as_deref())
+            .map_err(VnidropError::invalid_input)?;
         self.limits
-            .validate_metadata_text("sender name", metadata.sender_name.as_deref())?;
+            .validate_metadata_text("sender name", metadata.sender_name.as_deref())
+            .map_err(VnidropError::invalid_input)?;
         self.repository
             .insert_transfer(TransferUpsert {
                 transfer_id,
@@ -66,7 +74,8 @@ impl CoreInner {
                 total_size: 0,
                 access_mode: mode_to_storage(&metadata.access_mode),
             })
-            .await?;
+            .await
+            .map_err(VnidropError::repository)?;
         let (cancel, mut cancelled) = oneshot::channel();
         self.active_transfers
             .lock()
@@ -79,8 +88,10 @@ impl CoreInner {
                 },
             );
         let (result, was_cancelled) = tokio::select! {
-            result = self.share_files_inner(sources, metadata) => (result, false),
+            result = self.share_files_inner(sources, metadata) => {
-            _ = &mut cancelled => (Err(anyhow::anyhow!("transfer cancelled")), true),
+                (result.map_err(VnidropError::transfer), false)
+            },
+            _ = &mut cancelled => (Err(VnidropError::cancelled("transfer cancelled")), true),
         };
         self.active_transfers
             .lock()
@@ -95,7 +106,7 @@ impl CoreInner {
                     "send",
                     "error",
                     "failed",
-                    json!({ "reason": error.to_string() }),
+                    json!({ "code": error.code(), "reason": error.reason() }),
                 );
                 let _ = self
                     .repository
@@ -107,7 +118,7 @@ impl CoreInner {
                     .await;
             }
         }
-        result
+        result.map_err(anyhow::Error::new)
     }
 
     pub(super) async fn share_files_inner(
@@ -145,7 +156,8 @@ impl CoreInner {
         let local_id = self
             .repository
             .transfer_local_id(metadata.transfer_id)
-            .await?;
+            .await
+            .map_err(VnidropError::repository)?;
         let tag_name = share_tag_name(&local_id);
         self.store
             .tags()
@@ -175,7 +187,7 @@ impl CoreInner {
             .await
         {
             let _ = self.store.tags().delete(&tag_name).await;
-            return Err(error);
+            return Err(VnidropError::repository(error).into());
         }
         // Map root + every collection member so provider ACL cannot fail-open
         // on child blob hashes that are not the collection root.

crates/vnidrop/src/tests.rs

@@ -1,5 +1,7 @@
 #[path = "tests/access_policy.rs"]
 mod access_policy_tests;
+#[path = "tests/error.rs"]
+mod error_tests;
 #[path = "tests/filesystem.rs"]
 mod filesystem_tests;
 #[path = "tests/handshake.rs"]

crates/vnidrop/src/tests/error.rs

@@ -0,0 +1,54 @@
+use std::io;
+
+use crate::VnidropError;
+
+#[test]
+fn transfer_boundary_classifies_operating_system_failures() {
+    let already_exists = VnidropError::transfer(io::Error::new(
+        io::ErrorKind::AlreadyExists,
+        "target exists",
+    ));
+    let permission = VnidropError::transfer(io::Error::new(
+        io::ErrorKind::PermissionDenied,
+        "access denied",
+    ));
+    let storage = VnidropError::transfer(io::Error::new(io::ErrorKind::StorageFull, "disk full"));
+    let filesystem =
+        VnidropError::transfer(io::Error::new(io::ErrorKind::NotFound, "folder missing"));
+
+    assert!(matches!(
+        already_exists,
+        VnidropError::DestinationExists { .. }
+    ));
+    assert!(matches!(
+        permission,
+        VnidropError::FilesystemPermission { .. }
+    ));
+    assert!(matches!(storage, VnidropError::StorageFull { .. }));
+    assert!(matches!(filesystem, VnidropError::Filesystem { .. }));
+}
+
+#[test]
+fn transfer_boundary_preserves_typed_errors_through_context() {
+    let error = anyhow::Error::new(VnidropError::Network {
+        reason: "connection reset".to_string(),
+    })
+    .context("download failed");
+
+    let classified = VnidropError::transfer(error);
+
+    assert!(matches!(
+        classified,
+        VnidropError::Network { ref reason } if reason == "download failed"
+    ));
+    assert_eq!(classified.code(), "network");
+}
+
+#[test]
+fn transfer_boundary_classifies_database_failures() {
+    let transfer = VnidropError::transfer(sqlx::Error::RowNotFound);
+    let approval = VnidropError::permission(sqlx::Error::RowNotFound);
+
+    assert!(matches!(transfer, VnidropError::Repository { .. }));
+    assert!(matches!(approval, VnidropError::Repository { .. }));
+}

crates/vnidrop/tests/output_sink.rs

@@ -8,6 +8,29 @@ use support::{
     receive_with_sink_response, receive_with_sink_v2_response, share_path,
     wait_for_receiver_request, MemoryOutputSink, TestNode,
 };
+use vnidrop::{PublishedOutput, ReceiveOutputSinkV2, VnidropError};
+
+struct ExistingDestinationSink;
+
+impl ReceiveOutputSinkV2 for ExistingDestinationSink {
+    fn start_file(&self, relative_path: String) -> Result<(), VnidropError> {
+        Err(VnidropError::DestinationExists {
+            reason: format!("destination already exists: {relative_path}"),
+        })
+    }
+
+    fn write_chunk(&self, _relative_path: String, _bytes: Vec<u8>) -> Result<(), VnidropError> {
+        unreachable!("a rejected file must not be written")
+    }
+
+    fn finish_file(&self, _relative_path: String) -> Result<PublishedOutput, VnidropError> {
+        unreachable!("a rejected file must not be finished")
+    }
+
+    fn abort_file(&self, _relative_path: String, _reason: String) -> Result<(), VnidropError> {
+        unreachable!("start_file failure must not be aborted")
+    }
+}
 
 #[test]
 fn versioned_sink_records_published_locator() {
@@ -89,10 +112,45 @@ fn reports_output_sink_write_failure() {
     )
     .unwrap_err();
 
-    assert!(error.contains("sink write failed"));
+    assert!(matches!(
+        error,
+        VnidropError::Filesystem { ref reason } if reason.contains("sink write failed")
+    ));
     assert_eq!(output_sink.terminal_state("hello.txt"), Some("aborted"));
 }
 
+#[test]
+fn preserves_typed_output_sink_failure() {
+    let source_dir = tempfile::tempdir().unwrap();
+    let source_path = source_dir.path().join("existing.txt");
+    std::fs::write(&source_path, b"new content").unwrap();
+    let sender = TestNode::new();
+    let receiver = TestNode::new();
+    let share = share_path(&sender.core, &source_path, 39, "existing.txt", false);
+
+    let error = receive_with_sink_v2_response(
+        &sender.core,
+        share.transfer_id,
+        receiver.core.arc(),
+        share.ticket,
+        Arc::new(ExistingDestinationSink),
+        true,
+    )
+    .unwrap_err();
+
+    assert!(matches!(error, VnidropError::DestinationExists { .. }));
+    assert!(receiver
+        .core
+        .list_events(Some(39))
+        .unwrap()
+        .iter()
+        .any(|event| {
+            event.phase == "error"
+                && event.kind == "failed"
+                && event.data_json.contains("\"code\":\"destination_exists\"")
+        }));
+}
+
 #[test]
 fn cancellation_during_export_aborts_open_sink_file() {
     // Gate the first write so export is mid-file when cancel runs. A large

crates/vnidrop/tests/support/mod.rs

@@ -292,12 +292,10 @@ pub fn receive_with_response(
     ticket: String,
     output_dir: &Path,
     accepted: bool,
-) -> Result<(), String> {
+) -> Result<(), VnidropError> {
     let output_dir = output_dir.to_string_lossy().to_string();
     let handle = std::thread::spawn(move || {
-        receiver
+        receiver.receive(ticket, output_dir, Some("receiver".to_string()))
-            .receive(ticket, output_dir, Some("receiver".to_string()))
-            .map_err(|error| error.to_string())
     });
     respond_to_pending_request(sender, transfer_id, accepted);
     handle.join().unwrap()
@@ -310,11 +308,9 @@ pub fn receive_with_sink_response(
     ticket: String,
     output_sink: Arc<dyn ReceiveOutputSink>,
     accepted: bool,
-) -> Result<(), String> {
+) -> Result<(), VnidropError> {
     let handle = std::thread::spawn(move || {
-        receiver
+        receiver.receive_with_output_sink(ticket, output_sink, Some("receiver".to_string()))
-            .receive_with_output_sink(ticket, output_sink, Some("receiver".to_string()))
-            .map_err(|error| error.to_string())
     });
     respond_to_pending_request(sender, transfer_id, accepted);
     handle.join().unwrap()
@@ -327,11 +323,9 @@ pub fn receive_with_sink_v2_response(
     ticket: String,
     output_sink: Arc<dyn ReceiveOutputSinkV2>,
     accepted: bool,
-) -> Result<(), String> {
+) -> Result<(), VnidropError> {
     let handle = std::thread::spawn(move || {
-        receiver
+        receiver.receive_with_output_sink_v2(ticket, output_sink, Some("receiver".to_string()))
-            .receive_with_output_sink_v2(ticket, output_sink, Some("receiver".to_string()))
-            .map_err(|error| error.to_string())
     });
     respond_to_pending_request(sender, transfer_id, accepted);
     handle.join().unwrap()

crates/vnidrop/tests/transfer.rs

@@ -1,6 +1,7 @@
 mod support;
 
 use support::{receive_with_response, share_path, TestNode};
+use vnidrop::VnidropError;
 
 #[test]
 fn transfers_file_between_two_cores() {
@@ -98,7 +99,7 @@ fn receive_refuses_to_overwrite_existing_destination() {
     let receiver = TestNode::new();
     let share = share_path(&sender.core, &source_path, 27, "existing.txt", false);
 
-    assert!(receive_with_response(
+    let error = receive_with_response(
         &sender.core,
         share.transfer_id,
         receiver.core.arc(),
@@ -106,7 +107,8 @@ fn receive_refuses_to_overwrite_existing_destination() {
         output_dir.path(),
         true,
     )
-    .is_err());
+    .unwrap_err();
+    assert!(matches!(error, VnidropError::DestinationExists { .. }));
     assert_eq!(std::fs::read(&output_path).unwrap(), b"keep content");
     assert!(std::fs::read_dir(output_dir.path())
         .unwrap()
@@ -115,4 +117,22 @@ fn receive_refuses_to_overwrite_existing_destination() {
             .file_name()
             .to_string_lossy()
             .contains(".part")));
+    let transfer = receiver
+        .core
+        .list_transfers()
+        .unwrap()
+        .into_iter()
+        .find(|transfer| transfer.transfer_id == 27)
+        .unwrap();
+    assert_eq!(transfer.status, "failed");
+    assert!(receiver
+        .core
+        .list_events(Some(27))
+        .unwrap()
+        .iter()
+        .any(|event| {
+            event.phase == "error"
+                && event.kind == "failed"
+                && event.data_json.contains("\"code\":\"destination_exists\"")
+        }));
 }

localization/strings.json

@@ -1281,6 +1281,20 @@
         "ru": "Не удалось загрузить сведения об устройстве."
       }
     },
+    "error_destination_exists": {
+      "context": "Error: a received file would overwrite an existing destination file.",
+      "translations": {
+        "en": "A file with the same name already exists in the destination. Choose another folder or remove the existing file.",
+        "fr": "Un fichier portant le même nom existe déjà dans la destination. Choisissez un autre dossier ou supprimez le fichier existant.",
+        "es": "Ya existe un archivo con el mismo nombre en el destino. Elija otra carpeta o elimine el archivo existente.",
+        "it": "Nella destinazione esiste già un file con lo stesso nome. Scelga un’altra cartella o rimuova il file esistente.",
+        "de": "Am Ziel ist bereits eine Datei mit demselben Namen vorhanden. Wählen Sie einen anderen Ordner oder entfernen Sie die vorhandene Datei.",
+        "pt": "Já existe um ficheiro com o mesmo nome no destino. Escolha outra pasta ou remova o ficheiro existente.",
+        "pl": "W miejscu docelowym istnieje już plik o tej samej nazwie. Wybierz inny folder lub usuń istniejący plik.",
+        "nl": "Er staat al een bestand met dezelfde naam in de doelmap. Kies een andere map of verwijder het bestaande bestand.",
+        "ru": "В папке назначения уже есть файл с таким именем. Выберите другую папку или удалите существующий файл."
+      }
+    },
     "error_filesystem": {
       "context": "Error: the selected files/folder could not be accessed.",
       "translations": {
@@ -1323,6 +1337,20 @@
         "ru": "VniDrop не удалось завершить запуск. Закройте приложение и повторите попытку."
       }
     },
+    "error_invalid_input": {
+      "context": "Error: transfer input or metadata is invalid.",
+      "translations": {
+        "en": "Some transfer information is invalid. Review your selection or ask the sender to share again.",
+        "fr": "Certaines informations du transfert ne sont pas valides. Vérifiez votre sélection ou demandez à l’expéditeur de partager à nouveau.",
+        "es": "Parte de la información de la transferencia no es válida. Revise la selección o pida al remitente que vuelva a compartirla.",
+        "it": "Alcune informazioni del trasferimento non sono valide. Controlli la selezione o chieda al mittente di condividere di nuovo.",
+        "de": "Einige Übertragungsinformationen sind ungültig. Prüfen Sie Ihre Auswahl oder bitten Sie den Absender, erneut zu teilen.",
+        "pt": "Algumas informações da transferência são inválidas. Reveja a seleção ou peça ao remetente para partilhar novamente.",
+        "pl": "Niektóre informacje o transferze są nieprawidłowe. Sprawdź wybór lub poproś nadawcę o ponowne udostępnienie.",
+        "nl": "Sommige overdrachtsgegevens zijn ongeldig. Controleer uw selectie of vraag de afzender opnieuw te delen.",
+        "ru": "Некоторые данные передачи недействительны. Проверьте выбор или попросите отправителя поделиться снова."
+      }
+    },
     "error_invalid_ticket": {
       "context": "Error: the invitation/ticket could not be parsed.",
       "translations": {
@@ -1365,6 +1393,20 @@
         "ru": "В этой сборке отсутствует нативная библиотека VniDrop."
       }
     },
+    "error_network": {
+      "context": "Error: the sender could not be reached over the local network.",
+      "translations": {
+        "en": "VniDrop could not reach the sender. Check the connection on both devices and try again.",
+        "fr": "VniDrop n’a pas pu joindre l’expéditeur. Vérifiez la connexion sur les deux appareils et réessayez.",
+        "es": "VniDrop no pudo contactar con el remitente. Compruebe la conexión en ambos dispositivos e inténtelo de nuevo.",
+        "it": "VniDrop non è riuscito a raggiungere il mittente. Controlli la connessione su entrambi i dispositivi e riprovi.",
+        "de": "VniDrop konnte den Absender nicht erreichen. Prüfen Sie die Verbindung auf beiden Geräten und versuchen Sie es erneut.",
+        "pt": "O VniDrop não conseguiu contactar o remetente. Verifique a ligação nos dois dispositivos e tente novamente.",
+        "pl": "VniDrop nie mógł połączyć się z nadawcą. Sprawdź połączenie na obu urządzeniach i spróbuj ponownie.",
+        "nl": "VniDrop kon de afzender niet bereiken. Controleer de verbinding op beide apparaten en probeer het opnieuw.",
+        "ru": "VniDrop не удалось связаться с отправителем. Проверьте подключение на обоих устройствах и повторите попытку."
+      }
+    },
     "error_nfc": {
       "context": "Error: the NFC tag could not be read/used.",
       "translations": {
@@ -1463,18 +1505,32 @@
         "ru": "VniDrop ещё запускается. Откройте приглашение снова через мгновение."
       }
     },
-    "error_transfer": {
+    "error_storage_full": {
-      "context": "Error: the transfer could not be completed.",
+      "context": "Error: the destination does not have enough free storage.",
       "translations": {
-        "en": "The transfer could not be completed. Check your connection and try again.",
+        "en": "There is not enough storage space to save this transfer. Free up space and try again.",
-        "fr": "Le transfert n’a pas pu être terminé. Vérifiez votre connexion et réessayez.",
+        "fr": "L’espace de stockage est insuffisant pour enregistrer ce transfert. Libérez de l’espace et réessayez.",
-        "es": "No se pudo completar la transferencia. Compruebe su conexión e inténtelo de nuevo.",
+        "es": "No hay suficiente espacio de almacenamiento para guardar esta transferencia. Libere espacio e inténtelo de nuevo.",
-        "it": "Impossibile completare il trasferimento. Controlli la connessione e riprovi.",
+        "it": "Lo spazio di archiviazione non è sufficiente per salvare il trasferimento. Liberi spazio e riprovi.",
-        "de": "Die Übertragung konnte nicht abgeschlossen werden. Überprüfen Sie Ihre Verbindung und versuchen Sie es erneut.",
+        "de": "Zum Speichern dieser Übertragung ist nicht genügend Speicherplatz vorhanden. Geben Sie Speicherplatz frei und versuchen Sie es erneut.",
-        "pt": "Não foi possível concluir a transferência. Verifique a sua ligação e tente novamente.",
+        "pt": "Não existe espaço de armazenamento suficiente para guardar esta transferência. Liberte espaço e tente novamente.",
-        "pl": "Nie udało się ukończyć transferu. Sprawdź połączenie i spróbuj ponownie.",
+        "pl": "Brakuje miejsca na zapisanie tego transferu. Zwolnij miejsce i spróbuj ponownie.",
-        "nl": "De overdracht kon niet worden voltooid. Controleer uw verbinding en probeer het opnieuw.",
+        "nl": "Er is onvoldoende opslagruimte om deze overdracht op te slaan. Maak ruimte vrij en probeer het opnieuw.",
-        "ru": "Не удалось завершить передачу. Проверьте подключение и повторите попытку."
+        "ru": "Недостаточно места для сохранения этой передачи. Освободите место и повторите попытку."
+      }
+    },
+    "error_transfer": {
+      "context": "Error: transfer data could not be processed; network failures use error_network.",
+      "translations": {
+        "en": "The transfer data could not be processed. Ask the sender to share it again.",
+        "fr": "Les données du transfert n’ont pas pu être traitées. Demandez à l’expéditeur de les partager à nouveau.",
+        "es": "No se pudieron procesar los datos de la transferencia. Pida al remitente que vuelva a compartirlos.",
+        "it": "Non è stato possibile elaborare i dati del trasferimento. Chieda al mittente di condividerli di nuovo.",
+        "de": "Die Übertragungsdaten konnten nicht verarbeitet werden. Bitten Sie den Absender, sie erneut zu teilen.",
+        "pt": "Não foi possível processar os dados da transferência. Peça ao remetente para os partilhar novamente.",
+        "pl": "Nie udało się przetworzyć danych transferu. Poproś nadawcę o ponowne udostępnienie.",
+        "nl": "De overdrachtsgegevens konden niet worden verwerkt. Vraag de afzender ze opnieuw te delen.",
+        "ru": "Не удалось обработать данные передачи. Попросите отправителя поделиться ими снова."
       }
     },
     "field_receiver_name": {

shared/src/androidMain/kotlin/com/vnidrop/app/core/FileSystemService.android.kt

@@ -7,6 +7,8 @@ import android.os.Build
 import android.os.Environment
 import android.provider.DocumentsContract
 import android.provider.MediaStore
+import android.system.ErrnoException
+import android.system.OsConstants
 import android.webkit.MimeTypeMap
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.remember
@@ -15,7 +17,9 @@ import androidx.core.net.toUri
 import uniffi.vnidrop.PublishedOutput
 import uniffi.vnidrop.ReceiveOutputSinkV2
 import uniffi.vnidrop.ReceivedLocatorKind
+import uniffi.vnidrop.VnidropException
 import java.io.File
+import java.io.IOException
 import java.io.OutputStream
 import java.net.URLConnection
 import java.util.UUID
@@ -248,6 +252,32 @@ private fun Context.expandShareDirectory(folder: PickedShareFile): List<PickedSh
 	return out
 }
 
+private inline fun <T> receiveSinkCall(block: () -> T): T =
+	try {
+		block()
+	} catch (error: VnidropException) {
+		throw error
+	} catch (error: Throwable) {
+		throw error.toReceiveSinkException()
+	}
+
+private fun Throwable.toReceiveSinkException(): VnidropException {
+	val reason = message ?: toString()
+	var current: Throwable? = this
+	while (current != null) {
+		if (current is ErrnoException && current.errno == OsConstants.ENOSPC) {
+			return VnidropException.StorageFull(reason)
+		}
+		current = current.cause
+	}
+	return when (this) {
+		is SecurityException -> VnidropException.FilesystemPermission(reason)
+		is IllegalArgumentException -> VnidropException.InvalidInput(reason)
+		is IOException, is IllegalStateException -> VnidropException.Filesystem(reason)
+		else -> VnidropException.Internal(reason)
+	}
+}
+
 /**
  * Writes into the shared system Downloads collection via MediaStore.
  *
@@ -266,6 +296,7 @@ private class AndroidMediaStoreDownloadsSink(
 	private val resolver = context.contentResolver
 
 	override fun startFile(relativePath: String) {
+		receiveSinkCall {
 			check(Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
 				"MediaStore Downloads requires Android 10 or newer"
 			}
@@ -273,8 +304,8 @@ private class AndroidMediaStoreDownloadsSink(
 			val parts = requireSafeRelativePathParts(relativePath)
 			val finalName = parts.last()
 			val relativeDir = mediaStoreRelativePath(parts.dropLast(1))
-		check(!mediaStoreItemExists(finalName, relativeDir)) {
+			if (mediaStoreItemExists(finalName, relativeDir)) {
-			"Destination already exists: $relativePath"
+				throw VnidropException.DestinationExists("Destination already exists: $relativePath")
 			}
 
 			val values = ContentValues().apply {
@@ -295,13 +326,16 @@ private class AndroidMediaStoreDownloadsSink(
 				}
 			pending[relativePath] = PendingDocument(stream, uri)
 		}
+	}
 
 	override fun writeChunk(relativePath: String, bytes: ByteArray) {
+		receiveSinkCall {
 			val document = pending[relativePath] ?: error("Output stream is not open for $relativePath")
 			document.stream.write(bytes)
 		}
+	}
 
-	override fun finishFile(relativePath: String): PublishedOutput {
+	override fun finishFile(relativePath: String): PublishedOutput = receiveSinkCall {
 		val document = pending.remove(relativePath) ?: error("Output stream is not open for $relativePath")
 		try {
 			document.stream.flush()
@@ -316,14 +350,16 @@ private class AndroidMediaStoreDownloadsSink(
 			resolver.delete(document.uri, null, null)
 			throw error
 		}
-		return PublishedOutput(ReceivedLocatorKind.ANDROID_MEDIA_STORE, document.uri.toString())
+		PublishedOutput(ReceivedLocatorKind.ANDROID_MEDIA_STORE, document.uri.toString())
 	}
 
 	override fun abortFile(relativePath: String, reason: String) {
-		val document = pending.remove(relativePath) ?: return
+		receiveSinkCall {
+			val document = pending.remove(relativePath) ?: return@receiveSinkCall
 			runCatching { document.stream.close() }
 			resolver.delete(document.uri, null, null)
 		}
+	}
 
 	private fun downloadsCollection(): Uri =
 		MediaStore.Downloads.getContentUri(MediaStore.VOLUME_EXTERNAL_PRIMARY)
@@ -390,11 +426,14 @@ private class AndroidTreeReceiveOutputSink(
 	private val pending = mutableMapOf<String, PendingDocument>()
 
 	override fun startFile(relativePath: String) {
+		receiveSinkCall {
 			check(relativePath !in pending) { "Output stream is already open for $relativePath" }
 			// Defense in depth: Rust also validates, but sinks must reject traversal alone.
 			requireSafeRelativePathParts(relativePath)
 			val (parent, finalName) = resolveParent(relativePath)
-		check(findChild(parent, finalName) == null) { "Destination already exists: $relativePath" }
+			if (findChild(parent, finalName) != null) {
+				throw VnidropException.DestinationExists("Destination already exists: $relativePath")
+			}
 			val temporaryName = ".$finalName.vnidrop-${UUID.randomUUID()}.part"
 			val temporaryUri = DocumentsContract.createDocument(
 				context.contentResolver,
@@ -406,17 +445,22 @@ private class AndroidTreeReceiveOutputSink(
 				?: error("Could not open output stream for $relativePath")
 			pending[relativePath] = PendingDocument(stream, temporaryUri, parent, finalName)
 		}
+	}
 
 	override fun writeChunk(relativePath: String, bytes: ByteArray) {
+		receiveSinkCall {
 			val document = pending[relativePath] ?: error("Output stream is not open for $relativePath")
 			document.stream.write(bytes)
 		}
+	}
 
-	override fun finishFile(relativePath: String): PublishedOutput {
+	override fun finishFile(relativePath: String): PublishedOutput = receiveSinkCall {
 		val document = pending.remove(relativePath) ?: error("Output stream is not open for $relativePath")
 		try {
 			document.stream.close()
-			check(findChild(document.parentUri, document.finalName) == null) { "Destination already exists: $relativePath" }
+			if (findChild(document.parentUri, document.finalName) != null) {
+				throw VnidropException.DestinationExists("Destination already exists: $relativePath")
+			}
 			val finalUri = checkNotNull(
 				DocumentsContract.renameDocument(
 					context.contentResolver,
@@ -424,7 +468,7 @@ private class AndroidTreeReceiveOutputSink(
 					document.finalName,
 				),
 			) { "Could not commit received file $relativePath" }
-			return PublishedOutput(ReceivedLocatorKind.ANDROID_DOCUMENT, finalUri.toString())
+			PublishedOutput(ReceivedLocatorKind.ANDROID_DOCUMENT, finalUri.toString())
 		} catch (error: Throwable) {
 			runCatching { document.stream.close() }
 			DocumentsContract.deleteDocument(context.contentResolver, document.temporaryUri)
@@ -433,10 +477,12 @@ private class AndroidTreeReceiveOutputSink(
 	}
 
 	override fun abortFile(relativePath: String, reason: String) {
-		val document = pending.remove(relativePath) ?: return
+		receiveSinkCall {
+			val document = pending.remove(relativePath) ?: return@receiveSinkCall
 			runCatching { document.stream.close() }
 			DocumentsContract.deleteDocument(context.contentResolver, document.temporaryUri)
 		}
+	}
 
 	private fun resolveParent(relativePath: String): Pair<Uri, String> {
 		val parts = requireSafeRelativePathParts(relativePath)

shared/src/commonMain/composeResources/values-de/strings.xml

@@ -84,12 +84,15 @@
     <string name="diagnostics_title">Diagnosedaten teilen</string>
     <string name="error_camera">Für das Scannen eines QR-Codes ist Kamerazugriff erforderlich.</string>
     <string name="error_device_info">Geräteinformationen konnten nicht geladen werden.</string>
+    <string name="error_destination_exists">Am Ziel ist bereits eine Datei mit demselben Namen vorhanden. Wählen Sie einen anderen Ordner oder entfernen Sie die vorhandene Datei.</string>
     <string name="error_filesystem">VniDrop konnte nicht auf die ausgewählten Dateien oder den Ordner zugreifen. Überprüfen Sie die Berechtigungen und versuchen Sie es erneut.</string>
     <string name="error_generic">Etwas ist schiefgelaufen. Versuchen Sie es erneut.</string>
     <string name="error_initialization">VniDrop konnte den Start nicht abschließen. Schließen Sie die App und versuchen Sie es erneut.</string>
+    <string name="error_invalid_input">Einige Übertragungsinformationen sind ungültig. Prüfen Sie Ihre Auswahl oder bitten Sie den Absender, erneut zu teilen.</string>
     <string name="error_invalid_ticket">Diese Einladung konnte nicht gelesen werden. Bitten Sie den Absender um eine neue.</string>
     <string name="error_invitation_empty">Diese Einladung ist leer. Versuchen Sie, sie erneut zu öffnen.</string>
     <string name="error_missing_native_library">Die native VniDrop-Bibliothek fehlt in diesem Build.</string>
+    <string name="error_network">VniDrop konnte den Absender nicht erreichen. Prüfen Sie die Verbindung auf beiden Geräten und versuchen Sie es erneut.</string>
     <string name="error_nfc">Dieses NFC-Tag konnte nicht verwendet werden. Versuchen Sie ein anderes.</string>
     <string name="error_permission">Der Absender hat diese Übertragung nicht genehmigt oder sie wurde abgelehnt.</string>
     <string name="error_repository">VniDrop konnte die Übertragungsdaten auf diesem Gerät nicht speichern.</string>
@@ -97,7 +100,8 @@
     <string name="error_share_empty">Wählen Sie mindestens ein Objekt zum Teilen aus.</string>
     <string name="error_socket_bind">VniDrop konnte seine Netzwerk-Sockets auf diesem Gerät nicht öffnen.</string>
     <string name="error_starting_up">VniDrop startet noch. Öffnen Sie die Einladung gleich erneut.</string>
-    <string name="error_transfer">Die Übertragung konnte nicht abgeschlossen werden. Überprüfen Sie Ihre Verbindung und versuchen Sie es erneut.</string>
+    <string name="error_storage_full">Zum Speichern dieser Übertragung ist nicht genügend Speicherplatz vorhanden. Geben Sie Speicherplatz frei und versuchen Sie es erneut.</string>
+    <string name="error_transfer">Die Übertragungsdaten konnten nicht verarbeitet werden. Bitten Sie den Absender, sie erneut zu teilen.</string>
     <string name="field_receiver_name">Empfängername</string>
     <string name="field_sender_name">Absendername</string>
     <string name="field_transfer_name">Übertragungsname</string>

shared/src/commonMain/composeResources/values-es/strings.xml

@@ -84,12 +84,15 @@
     <string name="diagnostics_title">Compartir diagnósticos</string>
     <string name="error_camera">Se necesita acceso a la cámara para escanear un código QR.</string>
     <string name="error_device_info">No se pudo cargar la información del dispositivo.</string>
+    <string name="error_destination_exists">Ya existe un archivo con el mismo nombre en el destino. Elija otra carpeta o elimine el archivo existente.</string>
     <string name="error_filesystem">VniDrop no pudo acceder a los archivos o la carpeta seleccionados. Compruebe los permisos e inténtelo de nuevo.</string>
     <string name="error_generic">Algo salió mal. Inténtelo de nuevo.</string>
     <string name="error_initialization">VniDrop no pudo terminar de iniciarse. Cierre la app e inténtelo de nuevo.</string>
+    <string name="error_invalid_input">Parte de la información de la transferencia no es válida. Revise la selección o pida al remitente que vuelva a compartirla.</string>
     <string name="error_invalid_ticket">No se pudo leer esta invitación. Pida al remitente una nueva.</string>
     <string name="error_invitation_empty">Esa invitación está vacía. Intente abrirla de nuevo.</string>
     <string name="error_missing_native_library">Falta la biblioteca nativa de VniDrop en esta versión.</string>
+    <string name="error_network">VniDrop no pudo contactar con el remitente. Compruebe la conexión en ambos dispositivos e inténtelo de nuevo.</string>
     <string name="error_nfc">No se pudo usar esta etiqueta NFC. Pruebe con otra.</string>
     <string name="error_permission">El remitente no ha aprobado esta transferencia, o fue rechazada.</string>
     <string name="error_repository">VniDrop no pudo guardar los datos de la transferencia en este dispositivo.</string>
@@ -97,7 +100,8 @@
     <string name="error_share_empty">Seleccione al menos un elemento para compartir.</string>
     <string name="error_socket_bind">VniDrop no pudo abrir sus sockets de red en este dispositivo.</string>
     <string name="error_starting_up">VniDrop todavía se está iniciando. Vuelva a abrir la invitación en un momento.</string>
-    <string name="error_transfer">No se pudo completar la transferencia. Compruebe su conexión e inténtelo de nuevo.</string>
+    <string name="error_storage_full">No hay suficiente espacio de almacenamiento para guardar esta transferencia. Libere espacio e inténtelo de nuevo.</string>
+    <string name="error_transfer">No se pudieron procesar los datos de la transferencia. Pida al remitente que vuelva a compartirlos.</string>
     <string name="field_receiver_name">Nombre del destinatario</string>
     <string name="field_sender_name">Nombre del remitente</string>
     <string name="field_transfer_name">Nombre de la transferencia</string>

shared/src/commonMain/composeResources/values-fr/strings.xml

@@ -84,12 +84,15 @@
     <string name="diagnostics_title">Partager les diagnostics</string>
     <string name="error_camera">L’accès à la caméra est nécessaire pour scanner un QR code.</string>
     <string name="error_device_info">Impossible de charger les informations de l’appareil.</string>
+    <string name="error_destination_exists">Un fichier portant le même nom existe déjà dans la destination. Choisissez un autre dossier ou supprimez le fichier existant.</string>
     <string name="error_filesystem">VniDrop n’a pas pu accéder aux fichiers ou au dossier sélectionnés. Vérifiez les autorisations et réessayez.</string>
     <string name="error_generic">Une erreur est survenue. Réessayez.</string>
     <string name="error_initialization">VniDrop n’a pas pu terminer son démarrage. Fermez l’app et réessayez.</string>
+    <string name="error_invalid_input">Certaines informations du transfert ne sont pas valides. Vérifiez votre sélection ou demandez à l’expéditeur de partager à nouveau.</string>
     <string name="error_invalid_ticket">Cette invitation n’a pas pu être lue. Demandez-en une nouvelle à l’expéditeur.</string>
     <string name="error_invitation_empty">Cette invitation est vide. Essayez de l’ouvrir à nouveau.</string>
     <string name="error_missing_native_library">La bibliothèque native de VniDrop est absente de cette version.</string>
+    <string name="error_network">VniDrop n’a pas pu joindre l’expéditeur. Vérifiez la connexion sur les deux appareils et réessayez.</string>
     <string name="error_nfc">Ce tag NFC n’a pas pu être utilisé. Essayez-en un autre.</string>
     <string name="error_permission">L’expéditeur n’a pas approuvé ce transfert, ou il a été refusé.</string>
     <string name="error_repository">VniDrop n’a pas pu enregistrer les données de transfert sur cet appareil.</string>
@@ -97,7 +100,8 @@
     <string name="error_share_empty">Sélectionnez au moins un élément à partager.</string>
     <string name="error_socket_bind">VniDrop n’a pas pu ouvrir ses sockets réseau sur cet appareil.</string>
     <string name="error_starting_up">VniDrop démarre encore. Rouvrez l’invitation dans un instant.</string>
-    <string name="error_transfer">Le transfert n’a pas pu être terminé. Vérifiez votre connexion et réessayez.</string>
+    <string name="error_storage_full">L’espace de stockage est insuffisant pour enregistrer ce transfert. Libérez de l’espace et réessayez.</string>
+    <string name="error_transfer">Les données du transfert n’ont pas pu être traitées. Demandez à l’expéditeur de les partager à nouveau.</string>
     <string name="field_receiver_name">Nom du destinataire</string>
     <string name="field_sender_name">Nom de l’expéditeur</string>
     <string name="field_transfer_name">Nom du transfert</string>

shared/src/commonMain/composeResources/values-it/strings.xml

@@ -84,12 +84,15 @@
     <string name="diagnostics_title">Condividi dati diagnostici</string>
     <string name="error_camera">Per scansionare un codice QR è necessario l’accesso alla fotocamera.</string>
     <string name="error_device_info">Impossibile caricare le informazioni sul dispositivo.</string>
+    <string name="error_destination_exists">Nella destinazione esiste già un file con lo stesso nome. Scelga un’altra cartella o rimuova il file esistente.</string>
     <string name="error_filesystem">VniDrop non ha potuto accedere ai file o alla cartella selezionati. Controlli le autorizzazioni e riprovi.</string>
     <string name="error_generic">Qualcosa è andato storto. Riprovi.</string>
     <string name="error_initialization">VniDrop non ha potuto completare l’avvio. Chiuda l’app e riprovi.</string>
+    <string name="error_invalid_input">Alcune informazioni del trasferimento non sono valide. Controlli la selezione o chieda al mittente di condividere di nuovo.</string>
     <string name="error_invalid_ticket">Impossibile leggere questo invito. Ne chieda uno nuovo al mittente.</string>
     <string name="error_invitation_empty">Questo invito è vuoto. Provi ad aprirlo di nuovo.</string>
     <string name="error_missing_native_library">La libreria nativa di VniDrop non è presente in questa build.</string>
+    <string name="error_network">VniDrop non è riuscito a raggiungere il mittente. Controlli la connessione su entrambi i dispositivi e riprovi.</string>
     <string name="error_nfc">Impossibile usare questo tag NFC. Ne provi un altro.</string>
     <string name="error_permission">Il mittente non ha approvato questo trasferimento, oppure è stato rifiutato.</string>
     <string name="error_repository">VniDrop non ha potuto salvare i dati del trasferimento su questo dispositivo.</string>
@@ -97,7 +100,8 @@
     <string name="error_share_empty">Selezioni almeno un elemento da condividere.</string>
     <string name="error_socket_bind">VniDrop non ha potuto aprire i suoi socket di rete su questo dispositivo.</string>
     <string name="error_starting_up">VniDrop è ancora in fase di avvio. Riapra l’invito tra un momento.</string>
-    <string name="error_transfer">Impossibile completare il trasferimento. Controlli la connessione e riprovi.</string>
+    <string name="error_storage_full">Lo spazio di archiviazione non è sufficiente per salvare il trasferimento. Liberi spazio e riprovi.</string>
+    <string name="error_transfer">Non è stato possibile elaborare i dati del trasferimento. Chieda al mittente di condividerli di nuovo.</string>
     <string name="field_receiver_name">Nome del destinatario</string>
     <string name="field_sender_name">Nome del mittente</string>
     <string name="field_transfer_name">Nome del trasferimento</string>

shared/src/commonMain/composeResources/values-nl/strings.xml

@@ -84,12 +84,15 @@
     <string name="diagnostics_title">Diagnostische gegevens delen</string>
     <string name="error_camera">Voor het scannen van een QR-code is toegang tot de camera vereist.</string>
     <string name="error_device_info">Apparaatgegevens konden niet worden geladen.</string>
+    <string name="error_destination_exists">Er staat al een bestand met dezelfde naam in de doelmap. Kies een andere map of verwijder het bestaande bestand.</string>
     <string name="error_filesystem">VniDrop kon geen toegang krijgen tot de geselecteerde bestanden of map. Controleer de machtigingen en probeer het opnieuw.</string>
     <string name="error_generic">Er is iets misgegaan. Probeer het opnieuw.</string>
     <string name="error_initialization">VniDrop kon het opstarten niet voltooien. Sluit de app en probeer het opnieuw.</string>
+    <string name="error_invalid_input">Sommige overdrachtsgegevens zijn ongeldig. Controleer uw selectie of vraag de afzender opnieuw te delen.</string>
     <string name="error_invalid_ticket">Deze uitnodiging kon niet worden gelezen. Vraag de afzender om een nieuwe.</string>
     <string name="error_invitation_empty">Die uitnodiging is leeg. Probeer deze opnieuw te openen.</string>
     <string name="error_missing_native_library">De native VniDrop-bibliotheek ontbreekt in deze build.</string>
+    <string name="error_network">VniDrop kon de afzender niet bereiken. Controleer de verbinding op beide apparaten en probeer het opnieuw.</string>
     <string name="error_nfc">Deze NFC-tag kon niet worden gebruikt. Probeer een andere.</string>
     <string name="error_permission">De afzender heeft deze overdracht niet goedgekeurd, of deze is geweigerd.</string>
     <string name="error_repository">VniDrop kon de overdrachtsgegevens niet op dit apparaat bewaren.</string>
@@ -97,7 +100,8 @@
     <string name="error_share_empty">Selecteer minstens één item om te delen.</string>
     <string name="error_socket_bind">VniDrop kon zijn netwerksockets niet openen op dit apparaat.</string>
     <string name="error_starting_up">VniDrop is nog aan het opstarten. Open de uitnodiging zo meteen opnieuw.</string>
-    <string name="error_transfer">De overdracht kon niet worden voltooid. Controleer uw verbinding en probeer het opnieuw.</string>
+    <string name="error_storage_full">Er is onvoldoende opslagruimte om deze overdracht op te slaan. Maak ruimte vrij en probeer het opnieuw.</string>
+    <string name="error_transfer">De overdrachtsgegevens konden niet worden verwerkt. Vraag de afzender ze opnieuw te delen.</string>
     <string name="field_receiver_name">Naam van ontvanger</string>
     <string name="field_sender_name">Naam van afzender</string>
     <string name="field_transfer_name">Naam van overdracht</string>

shared/src/commonMain/composeResources/values-pl/strings.xml

@@ -84,12 +84,15 @@
     <string name="diagnostics_title">Udostępniaj diagnostykę</string>
     <string name="error_camera">Do zeskanowania kodu QR wymagany jest dostęp do aparatu.</string>
     <string name="error_device_info">Nie udało się wczytać informacji o urządzeniu.</string>
+    <string name="error_destination_exists">W miejscu docelowym istnieje już plik o tej samej nazwie. Wybierz inny folder lub usuń istniejący plik.</string>
     <string name="error_filesystem">VniDrop nie mógł uzyskać dostępu do wybranych plików lub folderu. Sprawdź uprawnienia i spróbuj ponownie.</string>
     <string name="error_generic">Coś poszło nie tak. Spróbuj ponownie.</string>
     <string name="error_initialization">VniDrop nie mógł dokończyć uruchamiania. Zamknij aplikację i spróbuj ponownie.</string>
+    <string name="error_invalid_input">Niektóre informacje o transferze są nieprawidłowe. Sprawdź wybór lub poproś nadawcę o ponowne udostępnienie.</string>
     <string name="error_invalid_ticket">Nie udało się odczytać tego zaproszenia. Poproś nadawcę o nowe.</string>
     <string name="error_invitation_empty">To zaproszenie jest puste. Spróbuj otworzyć je ponownie.</string>
     <string name="error_missing_native_library">W tej kompilacji brakuje natywnej biblioteki VniDrop.</string>
+    <string name="error_network">VniDrop nie mógł połączyć się z nadawcą. Sprawdź połączenie na obu urządzeniach i spróbuj ponownie.</string>
     <string name="error_nfc">Nie udało się użyć tego tagu NFC. Spróbuj innego.</string>
     <string name="error_permission">Nadawca nie zatwierdził tego transferu lub został on odrzucony.</string>
     <string name="error_repository">VniDrop nie mógł zapisać danych transferu na tym urządzeniu.</string>
@@ -97,7 +100,8 @@
     <string name="error_share_empty">Wybierz co najmniej jeden element do udostępnienia.</string>
     <string name="error_socket_bind">VniDrop nie mógł otworzyć gniazd sieciowych na tym urządzeniu.</string>
     <string name="error_starting_up">VniDrop jeszcze się uruchamia. Otwórz zaproszenie ponownie za chwilę.</string>
-    <string name="error_transfer">Nie udało się ukończyć transferu. Sprawdź połączenie i spróbuj ponownie.</string>
+    <string name="error_storage_full">Brakuje miejsca na zapisanie tego transferu. Zwolnij miejsce i spróbuj ponownie.</string>
+    <string name="error_transfer">Nie udało się przetworzyć danych transferu. Poproś nadawcę o ponowne udostępnienie.</string>
     <string name="field_receiver_name">Nazwa odbiorcy</string>
     <string name="field_sender_name">Nazwa nadawcy</string>
     <string name="field_transfer_name">Nazwa transferu</string>

shared/src/commonMain/composeResources/values-pt/strings.xml

@@ -84,12 +84,15 @@
     <string name="diagnostics_title">Partilhar diagnósticos</string>
     <string name="error_camera">É necessário acesso à câmara para ler um código QR.</string>
     <string name="error_device_info">Não foi possível carregar as informações do dispositivo.</string>
+    <string name="error_destination_exists">Já existe um ficheiro com o mesmo nome no destino. Escolha outra pasta ou remova o ficheiro existente.</string>
     <string name="error_filesystem">O VniDrop não conseguiu aceder aos ficheiros ou à pasta selecionados. Verifique as permissões e tente novamente.</string>
     <string name="error_generic">Algo correu mal. Tente novamente.</string>
     <string name="error_initialization">O VniDrop não conseguiu concluir o arranque. Feche a app e tente novamente.</string>
+    <string name="error_invalid_input">Algumas informações da transferência são inválidas. Reveja a seleção ou peça ao remetente para partilhar novamente.</string>
     <string name="error_invalid_ticket">Não foi possível ler este convite. Peça um novo ao remetente.</string>
     <string name="error_invitation_empty">Esse convite está vazio. Tente abri-lo novamente.</string>
     <string name="error_missing_native_library">A biblioteca nativa do VniDrop está em falta nesta compilação.</string>
+    <string name="error_network">O VniDrop não conseguiu contactar o remetente. Verifique a ligação nos dois dispositivos e tente novamente.</string>
     <string name="error_nfc">Não foi possível utilizar esta etiqueta NFC. Tente outra.</string>
     <string name="error_permission">O remetente não aprovou esta transferência, ou foi recusada.</string>
     <string name="error_repository">O VniDrop não conseguiu guardar os dados da transferência neste dispositivo.</string>
@@ -97,7 +100,8 @@
     <string name="error_share_empty">Selecione pelo menos um item para partilhar.</string>
     <string name="error_socket_bind">O VniDrop não conseguiu abrir os seus sockets de rede neste dispositivo.</string>
     <string name="error_starting_up">O VniDrop ainda está a iniciar. Abra o convite novamente dentro de momentos.</string>
-    <string name="error_transfer">Não foi possível concluir a transferência. Verifique a sua ligação e tente novamente.</string>
+    <string name="error_storage_full">Não existe espaço de armazenamento suficiente para guardar esta transferência. Liberte espaço e tente novamente.</string>
+    <string name="error_transfer">Não foi possível processar os dados da transferência. Peça ao remetente para os partilhar novamente.</string>
     <string name="field_receiver_name">Nome do destinatário</string>
     <string name="field_sender_name">Nome do remetente</string>
     <string name="field_transfer_name">Nome da transferência</string>

shared/src/commonMain/composeResources/values-ru/strings.xml

@@ -84,12 +84,15 @@
     <string name="diagnostics_title">Делиться диагностикой</string>
     <string name="error_camera">Для сканирования QR-кода требуется доступ к камере.</string>
     <string name="error_device_info">Не удалось загрузить сведения об устройстве.</string>
+    <string name="error_destination_exists">В папке назначения уже есть файл с таким именем. Выберите другую папку или удалите существующий файл.</string>
     <string name="error_filesystem">VniDrop не удалось получить доступ к выбранным файлам или папке. Проверьте разрешения и повторите попытку.</string>
     <string name="error_generic">Что-то пошло не так. Повторите попытку.</string>
     <string name="error_initialization">VniDrop не удалось завершить запуск. Закройте приложение и повторите попытку.</string>
+    <string name="error_invalid_input">Некоторые данные передачи недействительны. Проверьте выбор или попросите отправителя поделиться снова.</string>
     <string name="error_invalid_ticket">Не удалось прочитать это приглашение. Попросите отправителя прислать новое.</string>
     <string name="error_invitation_empty">Это приглашение пустое. Попробуйте открыть его снова.</string>
     <string name="error_missing_native_library">В этой сборке отсутствует нативная библиотека VniDrop.</string>
+    <string name="error_network">VniDrop не удалось связаться с отправителем. Проверьте подключение на обоих устройствах и повторите попытку.</string>
     <string name="error_nfc">Не удалось использовать эту NFC-метку. Попробуйте другую.</string>
     <string name="error_permission">Отправитель не одобрил эту передачу, или она была отклонена.</string>
     <string name="error_repository">VniDrop не удалось сохранить данные передачи на этом устройстве.</string>
@@ -97,7 +100,8 @@
     <string name="error_share_empty">Выберите хотя бы один объект для отправки.</string>
     <string name="error_socket_bind">VniDrop не удалось открыть сетевые сокеты на этом устройстве.</string>
     <string name="error_starting_up">VniDrop ещё запускается. Откройте приглашение снова через мгновение.</string>
-    <string name="error_transfer">Не удалось завершить передачу. Проверьте подключение и повторите попытку.</string>
+    <string name="error_storage_full">Недостаточно места для сохранения этой передачи. Освободите место и повторите попытку.</string>
+    <string name="error_transfer">Не удалось обработать данные передачи. Попросите отправителя поделиться ими снова.</string>
     <string name="field_receiver_name">Имя получателя</string>
     <string name="field_sender_name">Имя отправителя</string>
     <string name="field_transfer_name">Название передачи</string>

shared/src/commonMain/composeResources/values/strings.xml

@@ -84,12 +84,15 @@
     <string name="diagnostics_title">Share diagnostics</string>
     <string name="error_camera">Camera access is required to scan a QR code.</string>
     <string name="error_device_info">Could not load device information.</string>
+    <string name="error_destination_exists">A file with the same name already exists in the destination. Choose another folder or remove the existing file.</string>
     <string name="error_filesystem">VniDrop could not access the selected files or folder. Check permissions and try again.</string>
     <string name="error_generic">Something went wrong. Try again.</string>
     <string name="error_initialization">VniDrop could not finish starting up. Close the app and try again.</string>
+    <string name="error_invalid_input">Some transfer information is invalid. Review your selection or ask the sender to share again.</string>
     <string name="error_invalid_ticket">This invitation could not be read. Ask the sender for a new one.</string>
     <string name="error_invitation_empty">That invitation is empty. Try opening it again.</string>
     <string name="error_missing_native_library">The native VniDrop library is missing from this build.</string>
+    <string name="error_network">VniDrop could not reach the sender. Check the connection on both devices and try again.</string>
     <string name="error_nfc">This NFC tag could not be used. Try another tag.</string>
     <string name="error_permission">The sender has not approved this transfer, or it was refused.</string>
     <string name="error_repository">VniDrop could not save transfer data on this device.</string>
@@ -97,7 +100,8 @@
     <string name="error_share_empty">Select at least one item to share.</string>
     <string name="error_socket_bind">VniDrop could not open its network sockets on this device.</string>
     <string name="error_starting_up">VniDrop is still starting. Open the invitation again in a moment.</string>
-    <string name="error_transfer">The transfer could not be completed. Check your connection and try again.</string>
+    <string name="error_storage_full">There is not enough storage space to save this transfer. Free up space and try again.</string>
+    <string name="error_transfer">The transfer data could not be processed. Ask the sender to share it again.</string>
     <string name="field_receiver_name">Receiver name</string>
     <string name="field_sender_name">Sender name</string>
     <string name="field_transfer_name">Transfer name</string>

shared/src/commonMain/kotlin/com/vnidrop/app/feature/receive/ReceiveViewModel.kt

@@ -16,6 +16,7 @@ import com.vnidrop.app.ui.feedback.UiMessage
 import com.vnidrop.app.ui.feedback.UiMessageController
 import com.vnidrop.app.ui.feedback.UiMessageTone
 import com.vnidrop.app.ui.feedback.UiText
+import com.vnidrop.app.ui.feedback.canRetryWithoutChangingInput
 import com.vnidrop.app.ui.feedback.isUserCancellation
 import com.vnidrop.app.ui.feedback.toUiText
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -206,8 +207,12 @@ class ReceiveViewModel(
 						UiMessage(
 							text = uiText,
 							tone = UiMessageTone.Error,
-							actionLabel = UiText.Resource(Res.string.button_retry),
+							actionLabel = if (error.canRetryWithoutChangingInput()) {
-							onAction = { receive() },
+								UiText.Resource(Res.string.button_retry)
+							} else {
+								null
+							},
+							onAction = if (error.canRetryWithoutChangingInput()) ({ receive() }) else null,
 						),
 					)
 				},

shared/src/commonMain/kotlin/com/vnidrop/app/ui/feedback/UserFacingError.kt

@@ -3,9 +3,11 @@ package com.vnidrop.app.ui.feedback
 import uniffi.vnidrop.VnidropException
 import vnidrop.shared.generated.resources.Res
 import vnidrop.shared.generated.resources.error_device_info
+import vnidrop.shared.generated.resources.error_destination_exists
 import vnidrop.shared.generated.resources.error_filesystem
 import vnidrop.shared.generated.resources.error_generic
 import vnidrop.shared.generated.resources.error_initialization
+import vnidrop.shared.generated.resources.error_invalid_input
 import vnidrop.shared.generated.resources.error_invalid_ticket
 import vnidrop.shared.generated.resources.error_invitation_empty
 import vnidrop.shared.generated.resources.error_missing_native_library
@@ -15,8 +17,10 @@ import vnidrop.shared.generated.resources.error_selection_failed
 import vnidrop.shared.generated.resources.error_socket_bind
 import vnidrop.shared.generated.resources.error_camera
 import vnidrop.shared.generated.resources.error_nfc
+import vnidrop.shared.generated.resources.error_network
 import vnidrop.shared.generated.resources.error_share_empty
 import vnidrop.shared.generated.resources.error_starting_up
+import vnidrop.shared.generated.resources.error_storage_full
 import vnidrop.shared.generated.resources.error_transfer
 
 /**
@@ -29,8 +33,14 @@ fun Throwable.toUiText(): UiText =
 		is VnidropException.Ticket -> UiText.Resource(Res.string.error_invalid_ticket)
 		is VnidropException.Permission -> UiText.Resource(Res.string.error_permission)
 		is VnidropException.Filesystem -> UiText.Resource(Res.string.error_filesystem)
+		is VnidropException.FilesystemPermission -> UiText.Resource(Res.string.error_filesystem)
+		is VnidropException.DestinationExists -> UiText.Resource(Res.string.error_destination_exists)
+		is VnidropException.StorageFull -> UiText.Resource(Res.string.error_storage_full)
+		is VnidropException.Network -> UiText.Resource(Res.string.error_network)
 		is VnidropException.Transfer -> transferUiText(reason)
 		is VnidropException.Repository -> UiText.Resource(Res.string.error_repository)
+		is VnidropException.Cancelled -> UiText.Resource(Res.string.error_generic)
+		is VnidropException.InvalidInput -> UiText.Resource(Res.string.error_invalid_input)
 		is VnidropException.Initialization -> initializationUiText(reason)
 		is VnidropException.Internal -> reasonHints(reason) ?: UiText.Resource(Res.string.error_generic)
 		else -> reasonHints(technicalDetail()) ?: UiText.Resource(Res.string.error_generic)
@@ -38,6 +48,7 @@ fun Throwable.toUiText(): UiText =
 
 /** User intentionally backed out of a flow — do not treat as a failure snackbar. */
 fun Throwable.isUserCancellation(): Boolean {
+	if (this is VnidropException.Cancelled) return true
 	val haystack = technicalDetail().lowercase()
 	if (haystack.isBlank()) return false
 	return haystack.contains("cancelled") ||
@@ -46,15 +57,26 @@ fun Throwable.isUserCancellation(): Boolean {
 		haystack.contains("user canceled")
 }
 
+fun Throwable.canRetryWithoutChangingInput(): Boolean =
+	this !is VnidropException.FilesystemPermission &&
+		this !is VnidropException.DestinationExists &&
+		this !is VnidropException.InvalidInput
+
 /** Prefer [VnidropException.reason] when present; else [Throwable.message]. */
 fun Throwable.technicalDetail(): String =
 	when (this) {
 		is VnidropException.Initialization -> reason
 		is VnidropException.Ticket -> reason
 		is VnidropException.Filesystem -> reason
+		is VnidropException.FilesystemPermission -> reason
+		is VnidropException.DestinationExists -> reason
+		is VnidropException.StorageFull -> reason
+		is VnidropException.Network -> reason
 		is VnidropException.Transfer -> reason
 		is VnidropException.Permission -> reason
 		is VnidropException.Repository -> reason
+		is VnidropException.Cancelled -> reason
+		is VnidropException.InvalidInput -> reason
 		is VnidropException.Internal -> reason
 		else -> message.orEmpty()
 	}

shared/src/commonTest/kotlin/com/vnidrop/app/feature/ViewModelsTest.kt

@@ -50,9 +50,11 @@ import kotlin.test.assertContentEquals
 import kotlin.test.assertFalse
 import kotlin.test.assertNotNull
 import kotlin.test.assertTrue
+import uniffi.vnidrop.VnidropException
 import vnidrop.shared.generated.resources.Res
 import vnidrop.shared.generated.resources.button_show_in_files
 import vnidrop.shared.generated.resources.error_permission
+import vnidrop.shared.generated.resources.error_destination_exists
 import vnidrop.shared.generated.resources.receive_open_files_failed
 
 @OptIn(ExperimentalCoroutinesApi::class)
@@ -560,6 +562,29 @@ class ViewModelsTest {
 		)
 	}
 
+	@Test
+	fun receiveViewModelDoesNotOfferBlindRetryForDestinationCollision() = runTest {
+		Dispatchers.setMain(StandardTestDispatcher(testScheduler))
+		val core = FakeCoreGateway().apply {
+			mutableState.value = mutableState.value.copy(isInitialized = true)
+			inspectionResult = Result.success(sampleTicketInspection())
+			receiveResult = Result.failure(VnidropException.DestinationExists("target exists"))
+		}
+		val messages = UiMessageController()
+		val viewModel = ReceiveViewModel(core, FakeFileSystemService(folder), preferences(), messages)
+		advanceUntilIdle()
+		viewModel.onInvitationResult(com.vnidrop.app.feature.receive.ReceiveMethod.QrCode, Result.success("ticket"))
+		advanceUntilIdle()
+
+		viewModel.receive()
+		advanceUntilIdle()
+		val message = messages.messages.first()
+
+		assertEquals(UiText.Resource(Res.string.error_destination_exists), message.text)
+		assertEquals(null, message.actionLabel)
+		assertEquals(null, message.onAction)
+	}
+
 	@Test
 	fun receiveViewModelCancelUsesActiveTransferId() = runTest {
 		Dispatchers.setMain(StandardTestDispatcher(testScheduler))

shared/src/commonTest/kotlin/com/vnidrop/app/ui/feedback/UserFacingErrorTest.kt

@@ -7,8 +7,10 @@ import kotlin.test.assertTrue
 import uniffi.vnidrop.VnidropException
 import vnidrop.shared.generated.resources.Res
 import vnidrop.shared.generated.resources.error_filesystem
+import vnidrop.shared.generated.resources.error_destination_exists
 import vnidrop.shared.generated.resources.error_generic
 import vnidrop.shared.generated.resources.error_initialization
+import vnidrop.shared.generated.resources.error_invalid_input
 import vnidrop.shared.generated.resources.error_invalid_ticket
 import vnidrop.shared.generated.resources.error_invitation_empty
 import vnidrop.shared.generated.resources.error_missing_native_library
@@ -18,8 +20,10 @@ import vnidrop.shared.generated.resources.error_selection_failed
 import vnidrop.shared.generated.resources.error_socket_bind
 import vnidrop.shared.generated.resources.error_camera
 import vnidrop.shared.generated.resources.error_nfc
+import vnidrop.shared.generated.resources.error_network
 import vnidrop.shared.generated.resources.error_share_empty
 import vnidrop.shared.generated.resources.error_starting_up
+import vnidrop.shared.generated.resources.error_storage_full
 import vnidrop.shared.generated.resources.error_transfer
 
 class UserFacingErrorTest {
@@ -37,6 +41,26 @@ class UserFacingErrorTest {
 			UiText.Resource(Res.string.error_filesystem),
 			VnidropException.Filesystem("permission denied opening path").toUiText(),
 		)
+		assertEquals(
+			UiText.Resource(Res.string.error_filesystem),
+			VnidropException.FilesystemPermission("folder is read-only").toUiText(),
+		)
+		assertEquals(
+			UiText.Resource(Res.string.error_destination_exists),
+			VnidropException.DestinationExists("destination already exists").toUiText(),
+		)
+		assertEquals(
+			UiText.Resource(Res.string.error_storage_full),
+			VnidropException.StorageFull("no space left").toUiText(),
+		)
+		assertEquals(
+			UiText.Resource(Res.string.error_network),
+			VnidropException.Network("connection reset").toUiText(),
+		)
+		assertEquals(
+			UiText.Resource(Res.string.error_invalid_input),
+			VnidropException.InvalidInput("invalid collection name").toUiText(),
+		)
 		assertEquals(
 			UiText.Resource(Res.string.error_transfer),
 			VnidropException.Transfer("connection reset").toUiText(),
@@ -119,6 +143,15 @@ class UserFacingErrorTest {
 		assertTrue(IllegalStateException("QR scanning was cancelled").isUserCancellation())
 		assertTrue(IllegalStateException("NFC writing was cancelled").isUserCancellation())
 		assertTrue(VnidropException.Transfer("transfer cancelled by user").isUserCancellation())
+		assertTrue(VnidropException.Cancelled("cancel requested").isUserCancellation())
 		assertFalse(IllegalStateException("sender refused").isUserCancellation())
 	}
+
+	@Test
+	fun retryRequiresChangingCollisionOrInvalidInput() {
+		assertFalse(VnidropException.FilesystemPermission("read-only").canRetryWithoutChangingInput())
+		assertFalse(VnidropException.DestinationExists("target exists").canRetryWithoutChangingInput())
+		assertFalse(VnidropException.InvalidInput("bad path").canRetryWithoutChangingInput())
+		assertTrue(VnidropException.Network("offline").canRetryWithoutChangingInput())
+	}
 }