feat(apple): collect transfers held for this device

Adds the opt-in foreground check and an explicit Check now, the waiting-to-
be-delivered list on the sender side, and honest reporting when a send could
not be delivered: a closed app is a delay, not a success nobody received.

The setting is off by default and its footer states that checking reveals
app-open times to remembered devices, since that is the reason it is a
setting at all.

Records in the design doc that this shipped as one global toggle rather than
the per-contact opt-in originally specified.

apple/VniDrop/Features/Contacts/ContactsModel.swift

@@ -32,6 +32,10 @@ struct ContactsState: Equatable {
 	var busyEndpoints: Set<String> = []
 	var busyOfferIds: Set<String> = []
 	var suggestions: [PairingSuggestion] = []
+	/// Transfers this device is holding for contacts that were not running.
+	var heldOffers: [HeldOfferModel] = []
+	var checkForOffersOnOpen = false
+	var isCheckingForOffers = false
 	var selectedEndpointId: String?
 
 	var selected: DeviceContact? {
@@ -75,6 +79,7 @@ final class ContactsModel: ObservableObject {
 		self.preferences = preferences
 		self.fileSystemService = fileSystemService
 		state.grantLifetime = preferences.preferences.grantLifetime
+		state.checkForOffersOnOpen = preferences.preferences.checkForOffersOnOpen
 
 		repository.signals
 			.sink { [weak self] signal in
@@ -130,6 +135,9 @@ final class ContactsModel: ObservableObject {
 		if case .success(let blocked) = await repository.blockedContacts() {
 			state.blocked = blocked
 		}
+		if case .success(let held) = await repository.heldOffers() {
+			state.heldOffers = held
+		}
 		state.pendingPairings = await repository.pendingPairings()
 		await refreshOffers()
 	}
@@ -205,6 +213,40 @@ final class ContactsModel: ObservableObject {
 		preferences.declinePairingSuggestion(suggestion.endpointId)
 	}
 
+	// MARK: - Collecting waiting transfers
+
+	func setCheckForOffersOnOpen(_ enabled: Bool) {
+		state.checkForOffersOnOpen = enabled
+		preferences.setCheckForOffersOnOpen(enabled)
+	}
+
+	/// Called when the app comes to the foreground.
+	///
+	/// Opt-in, because asking every contact whether they have something waiting
+	/// also tells them the app was opened. Never runs in the background.
+	func checkForOffersOnForeground() async {
+		guard state.checkForOffersOnOpen else { return }
+		_ = await collectWaitingOffers()
+	}
+
+	/// Explicit "check now". Returns how many transfers were collected so the
+	/// caller can report an empty result, which a silent refresh cannot.
+	@discardableResult
+	func collectWaitingOffers() async -> UInt64 {
+		guard !state.isCheckingForOffers else { return 0 }
+		state.isCheckingForOffers = true
+		defer { state.isCheckingForOffers = false }
+
+		switch await repository.pollContactsForOffers() {
+		case .success(let collected):
+			await refreshOffers()
+			return collected
+		case .failure(let error):
+			messages.error(error)
+			return 0
+		}
+	}
+
 	// MARK: - Selection
 
 	func select(_ endpointId: String?) { state.selectedEndpointId = endpointId }
@@ -290,8 +332,13 @@ final class ContactsModel: ObservableObject {
 		)
 		await fileSystemService.discardPickedFiles(files)
 		switch result {
-		case .success:
-			messages.tryShow(UiMessage(text: .resource(L10n.Send.transferCreated), tone: .success))
+		case .success(let outcome):
+			// A closed app is a delay, not a failure: say so rather than
+			// reporting success for something nobody has received.
+			let text: UiText = outcome.delivered
+				? .resource(L10n.Send.transferCreated)
+				: .resource(L10n.Contacts.offerHeld)
+			messages.tryShow(UiMessage(text: text, tone: outcome.delivered ? .success : .info))
 			await refresh()
 		case .failure(let error):
 			messages.error(error)

apple/VniDrop/Features/Contacts/ContactsScreen.swift

@@ -7,6 +7,8 @@ import SwiftUI
 /// not part of the send/receive flow.
 struct ContactsScreen: View {
 	@ObservedObject var model: ContactsModel
+	/// Reports an empty result, which a silent refresh cannot convey.
+	let onNothingWaiting: () -> Void
 
 	var body: some View {
 		Form {
@@ -30,6 +32,24 @@ struct ContactsScreen: View {
 				}
 			}
 
+			if !model.state.heldOffers.isEmpty {
+				Section(String(localized: L10n.Contacts.waitingTitle)) {
+					ForEach(model.state.heldOffers) { offer in
+						VStack(alignment: .leading, spacing: 2) {
+							Text(offer.transferName)
+							Text(String(offer.endpointId.prefix(16)))
+								.font(.caption.monospaced())
+								.foregroundStyle(.secondary)
+								.lineLimit(1)
+								.truncationMode(.middle)
+						}
+					}
+					Text(String(localized: L10n.Contacts.waitingHint))
+						.font(.footnote)
+						.foregroundStyle(.secondary)
+				}
+			}
+
 			if !model.state.blocked.isEmpty {
 				Section(String(localized: L10n.Contacts.blockedTitle)) {
 					ForEach(model.state.blocked, id: \.self) { endpointId in
@@ -43,6 +63,18 @@ struct ContactsScreen: View {
 				}
 			}
 
+			CollectOffersSection(
+				enabled: model.state.checkForOffersOnOpen,
+				isChecking: model.state.isCheckingForOffers,
+				onToggle: model.setCheckForOffersOnOpen,
+				onCheckNow: {
+					Task {
+						let collected = await model.collectWaitingOffers()
+						if collected == 0 { onNothingWaiting() }
+					}
+				}
+			)
+
 			GrantLifetimeSection(
 				selection: model.state.grantLifetime,
 				onSelect: model.setGrantLifetime
@@ -129,6 +161,36 @@ private struct BlockedRow: View {
 	}
 }
 
+private struct CollectOffersSection: View {
+	let enabled: Bool
+	let isChecking: Bool
+	let onToggle: (Bool) -> Void
+	let onCheckNow: () -> Void
+
+	var body: some View {
+		Section {
+			Toggle(
+				String(localized: L10n.Contacts.checkOnOpen),
+				isOn: Binding(get: { enabled }, set: onToggle)
+			)
+			Button(action: onCheckNow) {
+				HStack {
+					Text(String(localized: L10n.Contacts.checkNow))
+					if isChecking {
+						Spacer()
+						ProgressView().controlSize(.small)
+					}
+				}
+			}
+			.disabled(isChecking)
+		} footer: {
+			// The privacy cost is the point of the setting, so it is stated
+			// where the switch is, not buried elsewhere.
+			Text(String(localized: L10n.Contacts.checkOnOpenHint))
+		}
+	}
+}
+
 private struct GrantLifetimeSection: View {
 	let selection: GrantLifetimeOption
 	let onSelect: (GrantLifetimeOption) -> Void