Expand coverage for transport, chat, and media flows (#1056)

* Expand coverage for transport, chat, and media flows

* Stabilize transport and media coverage tests

---------

Co-authored-by: jack <jackjackbits@users.noreply.github.com>

bitchatTests/ChatViewModelExtensionsTests.swift

@@ -8,6 +8,11 @@
 import Testing
 import Foundation
 import Combine
+#if os(iOS)
+import UIKit
+#else
+import AppKit
+#endif
 @testable import bitchat
 
 // MARK: - Test Helpers
@@ -404,6 +409,274 @@ struct ChatViewModelNostrExtensionTests {
 
         #expect(!viewModel.deduplicationService.hasProcessedNostrEvent("evt-cache"))
     }
+
+    @Test @MainActor
+    func handleNostrEvent_presenceTracksParticipantWithoutTimelineMessage() async throws {
+        let (viewModel, _) = makeTestableViewModel()
+        let geohash = "u4pruydq"
+        let identity = try NostrIdentity.generate()
+
+        viewModel.switchLocationChannel(to: .location(GeohashChannel(level: .city, geohash: geohash)))
+
+        let event = NostrEvent(
+            pubkey: identity.publicKeyHex,
+            createdAt: Date(),
+            kind: .geohashPresence,
+            tags: [["g", geohash]],
+            content: ""
+        )
+        let signed = try event.sign(with: identity.schnorrSigningKey())
+
+        viewModel.handleNostrEvent(signed)
+
+        try? await Task.sleep(nanoseconds: 50_000_000)
+        #expect(viewModel.geohashParticipantCount(for: geohash) >= 1)
+        viewModel.publicMessagePipeline.flushIfNeeded()
+        #expect(viewModel.messages.isEmpty)
+    }
+
+    @Test @MainActor
+    func subscribeGiftWrap_deliveredAckUpdatesExistingMessage() async throws {
+        let (viewModel, _) = makeTestableViewModel()
+        let sender = try NostrIdentity.generate()
+        let recipient = try NostrIdentity.generate()
+        let convKey = PeerID(nostr_: sender.publicKeyHex)
+        let messageID = "geo-ack-delivered"
+
+        viewModel.privateChats[convKey] = [
+            BitchatMessage(
+                id: messageID,
+                sender: viewModel.nickname,
+                content: "Hello",
+                timestamp: Date(),
+                isRelay: false,
+                isPrivate: true,
+                recipientNickname: "Friend",
+                senderPeerID: viewModel.meshService.myPeerID,
+                deliveryStatus: .sent
+            )
+        ]
+
+        let content = try ackContent(type: .delivered, messageID: messageID, senderPeerID: PeerID(str: "0123456789abcdef"))
+        let giftWrap = try NostrProtocol.createPrivateMessage(
+            content: content,
+            recipientPubkey: recipient.publicKeyHex,
+            senderIdentity: sender
+        )
+
+        viewModel.subscribeGiftWrap(giftWrap, id: recipient)
+
+        let didUpdate = await TestHelpers.waitUntil(
+            { isDelivered(status: deliveryStatus(in: viewModel, peerID: convKey, messageID: messageID)) },
+            timeout: 0.5
+        )
+        #expect(didUpdate)
+    }
+
+    @Test @MainActor
+    func subscribeGiftWrap_readAckUpdatesExistingMessage() async throws {
+        let (viewModel, _) = makeTestableViewModel()
+        let sender = try NostrIdentity.generate()
+        let recipient = try NostrIdentity.generate()
+        let convKey = PeerID(nostr_: sender.publicKeyHex)
+        let messageID = "geo-ack-read"
+
+        viewModel.privateChats[convKey] = [
+            BitchatMessage(
+                id: messageID,
+                sender: viewModel.nickname,
+                content: "Hello",
+                timestamp: Date(),
+                isRelay: false,
+                isPrivate: true,
+                recipientNickname: "Friend",
+                senderPeerID: viewModel.meshService.myPeerID,
+                deliveryStatus: .delivered(to: "Friend", at: Date())
+            )
+        ]
+
+        let content = try ackContent(type: .readReceipt, messageID: messageID, senderPeerID: PeerID(str: "0123456789abcdef"))
+        let giftWrap = try NostrProtocol.createPrivateMessage(
+            content: content,
+            recipientPubkey: recipient.publicKeyHex,
+            senderIdentity: sender
+        )
+
+        viewModel.subscribeGiftWrap(giftWrap, id: recipient)
+
+        let didUpdate = await TestHelpers.waitUntil(
+            { isRead(status: deliveryStatus(in: viewModel, peerID: convKey, messageID: messageID)) },
+            timeout: 0.5
+        )
+        #expect(didUpdate)
+    }
+
+    @Test @MainActor
+    func handleGiftWrap_privateMessageStoresConversationAndMapping() async throws {
+        let (viewModel, _) = makeTestableViewModel()
+        let sender = try NostrIdentity.generate()
+        let recipient = try NostrIdentity.generate()
+        let messageID = "gift-private"
+        let convKey = PeerID(nostr_: sender.publicKeyHex)
+
+        let content = try privateMessageContent(
+            text: "Hello from gift wrap",
+            messageID: messageID,
+            senderPeerID: PeerID(str: "0123456789abcdef")
+        )
+        let giftWrap = try NostrProtocol.createPrivateMessage(
+            content: content,
+            recipientPubkey: recipient.publicKeyHex,
+            senderIdentity: sender
+        )
+
+        viewModel.handleGiftWrap(giftWrap, id: recipient)
+
+        let didStore = await TestHelpers.waitUntil(
+            { viewModel.privateChats[convKey]?.first?.content == "Hello from gift wrap" },
+            timeout: 0.5
+        )
+        #expect(didStore)
+        #expect(viewModel.nostrKeyMapping[convKey] == sender.publicKeyHex)
+        #expect(viewModel.sentGeoDeliveryAcks.contains(messageID))
+    }
+
+    @Test @MainActor
+    func handleGiftWrap_blockedSenderSkipsMessageStorage() async throws {
+        let (viewModel, _) = makeTestableViewModel()
+        let sender = try NostrIdentity.generate()
+        let recipient = try NostrIdentity.generate()
+        let messageID = "gift-blocked"
+        let convKey = PeerID(nostr_: sender.publicKeyHex)
+
+        viewModel.identityManager.setNostrBlocked(sender.publicKeyHex, isBlocked: true)
+
+        let content = try privateMessageContent(
+            text: "Blocked",
+            messageID: messageID,
+            senderPeerID: PeerID(str: "0123456789abcdef")
+        )
+        let giftWrap = try NostrProtocol.createPrivateMessage(
+            content: content,
+            recipientPubkey: recipient.publicKeyHex,
+            senderIdentity: sender
+        )
+
+        viewModel.handleGiftWrap(giftWrap, id: recipient)
+
+        try? await Task.sleep(nanoseconds: 50_000_000)
+        #expect(viewModel.privateChats[convKey] == nil)
+        #expect(viewModel.sentGeoDeliveryAcks.contains(messageID))
+    }
+
+    @Test @MainActor
+    func handleGiftWrap_deliveredAckUpdatesExistingMessage() async throws {
+        let (viewModel, _) = makeTestableViewModel()
+        let sender = try NostrIdentity.generate()
+        let recipient = try NostrIdentity.generate()
+        let convKey = PeerID(nostr_: sender.publicKeyHex)
+        let messageID = "gift-delivered"
+
+        viewModel.privateChats[convKey] = [
+            BitchatMessage(
+                id: messageID,
+                sender: viewModel.nickname,
+                content: "Hello",
+                timestamp: Date(),
+                isRelay: false,
+                isPrivate: true,
+                recipientNickname: "Friend",
+                senderPeerID: viewModel.meshService.myPeerID,
+                deliveryStatus: .sent
+            )
+        ]
+
+        let content = try ackContent(type: .delivered, messageID: messageID, senderPeerID: PeerID(str: "0123456789abcdef"))
+        let giftWrap = try NostrProtocol.createPrivateMessage(
+            content: content,
+            recipientPubkey: recipient.publicKeyHex,
+            senderIdentity: sender
+        )
+
+        viewModel.handleGiftWrap(giftWrap, id: recipient)
+
+        let didUpdate = await TestHelpers.waitUntil(
+            { isDelivered(status: deliveryStatus(in: viewModel, peerID: convKey, messageID: messageID)) },
+            timeout: 0.5
+        )
+        #expect(didUpdate)
+    }
+
+    @Test @MainActor
+    func findNoiseKey_matchesFavoriteStoredAsNpub() async throws {
+        let (viewModel, _) = makeTestableViewModel()
+        let identity = try NostrIdentity.generate()
+        let noiseKey = Data((0..<32).map { UInt8(($0 + 80) & 0xFF) })
+
+        FavoritesPersistenceService.shared.addFavorite(
+            peerNoisePublicKey: noiseKey,
+            peerNostrPublicKey: identity.npub,
+            peerNickname: "Alice"
+        )
+        defer { FavoritesPersistenceService.shared.removeFavorite(peerNoisePublicKey: noiseKey) }
+
+        #expect(viewModel.findNoiseKey(for: identity.publicKeyHex) == noiseKey)
+    }
+
+    @Test @MainActor
+    func findNoiseKey_matchesFavoriteStoredAsHex() async {
+        let (viewModel, _) = makeTestableViewModel()
+        let nostrHex = String(repeating: "ab", count: 32)
+        let noiseKey = Data((0..<32).map { UInt8(($0 + 112) & 0xFF) })
+
+        FavoritesPersistenceService.shared.addFavorite(
+            peerNoisePublicKey: noiseKey,
+            peerNostrPublicKey: nostrHex,
+            peerNickname: "Bob"
+        )
+        defer { FavoritesPersistenceService.shared.removeFavorite(peerNoisePublicKey: noiseKey) }
+
+        #expect(viewModel.findNoiseKey(for: nostrHex) == noiseKey)
+    }
+
+    @Test @MainActor
+    func handleFavoriteNotification_updatesFavoriteAssociation() async throws {
+        let (viewModel, _) = makeTestableViewModel()
+        let identity = try NostrIdentity.generate()
+        let noiseKey = Data((0..<32).map { UInt8(($0 + 144) & 0xFF) })
+
+        FavoritesPersistenceService.shared.addFavorite(
+            peerNoisePublicKey: noiseKey,
+            peerNostrPublicKey: identity.npub,
+            peerNickname: "Before"
+        )
+        defer { FavoritesPersistenceService.shared.removeFavorite(peerNoisePublicKey: noiseKey) }
+
+        viewModel.handleFavoriteNotification(
+            content: "FAVORITE:TRUE|NPUB:\(identity.npub)|Alice",
+            from: identity.publicKeyHex
+        )
+
+        let relationship = FavoritesPersistenceService.shared.getFavoriteStatus(for: noiseKey)
+        #expect(relationship?.peerNickname == "Alice")
+        #expect(relationship?.peerNostrPublicKey == identity.npub)
+        #expect(relationship?.isFavorite == true)
+    }
+
+    @Test @MainActor
+    func geohashDMHelpers_exposeMappingAndDisplayName() async {
+        let (viewModel, _) = makeTestableViewModel()
+        let nostrHex = String(repeating: "cd", count: 32)
+        let convKey = PeerID(nostr_: nostrHex)
+
+        viewModel.geoNicknames[nostrHex] = "Alice"
+        viewModel.startGeohashDM(withPubkeyHex: nostrHex)
+
+        #expect(viewModel.selectedPrivateChatPeer == convKey)
+        #expect(viewModel.fullNostrHex(forSenderPeerID: convKey) == nostrHex)
+        #expect(viewModel.geohashDisplayName(for: convKey).hasPrefix("Alice"))
+        #expect(viewModel.nostrPubkeyForDisplayName("Alice") == nostrHex)
+    }
 }
 
 // MARK: - Geohash Queue Tests
@@ -449,6 +722,302 @@ struct ChatViewModelGeoDMTests {
         #expect(viewModel.privateChats[convKey]?.count == 1)
         #expect(viewModel.sentGeoDeliveryAcks.contains(messageID))
     }
+
+    @Test @MainActor
+    func sendGeohashDM_requiresActiveLocationChannel() async {
+        let (viewModel, _) = makeTestableViewModel()
+        let convKey = PeerID(nostr_: "0000000000000000000000000000000000000000000000000000000000000001")
+
+        viewModel.sendGeohashDM("hello", to: convKey)
+
+        #expect(viewModel.privateChats[convKey] == nil)
+        #expect(viewModel.messages.count == 1)
+        #expect(viewModel.messages.last?.sender == "system")
+    }
+
+    @Test @MainActor
+    func sendGeohashDM_missingRecipientMapping_marksFailed() async {
+        let (viewModel, _) = makeTestableViewModel()
+        let geohash = "u4pruydq"
+        let convKey = PeerID(nostr_: "0000000000000000000000000000000000000000000000000000000000000002")
+
+        viewModel.switchLocationChannel(to: .location(GeohashChannel(level: .city, geohash: geohash)))
+        viewModel.sendGeohashDM("hello", to: convKey)
+
+        #expect(viewModel.privateChats[convKey]?.count == 1)
+        #expect(isFailed(status: viewModel.privateChats[convKey]?.last?.deliveryStatus))
+    }
+
+    @Test @MainActor
+    func sendGeohashDM_blockedRecipient_marksFailedAndAddsSystemMessage() async {
+        let (viewModel, _) = makeTestableViewModel()
+        let geohash = "u4pruydq"
+        let recipientHex = "0000000000000000000000000000000000000000000000000000000000000003"
+        let convKey = PeerID(nostr_: recipientHex)
+
+        viewModel.switchLocationChannel(to: .location(GeohashChannel(level: .city, geohash: geohash)))
+        viewModel.nostrKeyMapping[convKey] = recipientHex
+        viewModel.identityManager.setNostrBlocked(recipientHex, isBlocked: true)
+
+        viewModel.sendGeohashDM("hello", to: convKey)
+
+        #expect(viewModel.privateChats[convKey]?.count == 1)
+        #expect(isFailed(status: viewModel.privateChats[convKey]?.last?.deliveryStatus))
+        #expect(viewModel.messages.contains(where: { $0.sender == "system" }))
+    }
+
+    @Test @MainActor
+    func handlePrivateMessage_geohashViewingConversationRecordsReadReceipt() async throws {
+        let (viewModel, _) = makeTestableViewModel()
+        let geohash = "u4pruydq"
+        let senderPubkey = "0000000000000000000000000000000000000000000000000000000000000004"
+        let convKey = PeerID(nostr_: senderPubkey)
+        let messageID = "pm-viewing"
+
+        viewModel.switchLocationChannel(to: .location(GeohashChannel(level: .city, geohash: geohash)))
+        viewModel.selectedPrivateChatPeer = convKey
+
+        let identity = try viewModel.idBridge.deriveIdentity(forGeohash: geohash)
+        let packet = PrivateMessagePacket(messageID: messageID, content: "Hello")
+        let payloadData = try #require(packet.encode(), "Failed to encode private message")
+        let payload = NoisePayload(type: .privateMessage, data: payloadData)
+
+        viewModel.handlePrivateMessage(
+            payload,
+            senderPubkey: senderPubkey,
+            convKey: convKey,
+            id: identity,
+            messageTimestamp: Date()
+        )
+
+        #expect(viewModel.sentGeoDeliveryAcks.contains(messageID))
+        #expect(viewModel.sentReadReceipts.contains(messageID))
+        #expect(!viewModel.unreadPrivateMessages.contains(convKey))
+    }
+}
+
+struct ChatViewModelMediaTransferTests {
+
+    @Test @MainActor
+    func handleTransferEvent_updatesPrivateMessageProgressAndClearsMappingOnCompletion() async {
+        let (viewModel, _) = makeTestableViewModel()
+        let peerID = PeerID(str: "0102030405060708090a0b0c0d0e0f100102030405060708090a0b0c0d0e0f10")
+        let message = viewModel.enqueueMediaMessage(content: "[voice] clip.m4a", targetPeer: peerID)
+        let transferID = "transfer-1"
+
+        viewModel.registerTransfer(transferId: transferID, messageID: message.id)
+        viewModel.handleTransferEvent(.started(id: transferID, totalFragments: 4))
+        #expect(isPartiallyDelivered(status: deliveryStatus(in: viewModel, peerID: peerID, messageID: message.id), reached: 0, total: 4))
+
+        viewModel.handleTransferEvent(.updated(id: transferID, sentFragments: 2, totalFragments: 4))
+        #expect(isPartiallyDelivered(status: deliveryStatus(in: viewModel, peerID: peerID, messageID: message.id), reached: 2, total: 4))
+
+        viewModel.handleTransferEvent(.completed(id: transferID, totalFragments: 4))
+        #expect(isSent(status: deliveryStatus(in: viewModel, peerID: peerID, messageID: message.id)))
+        #expect(viewModel.messageIDToTransferId[message.id] == nil)
+        #expect(viewModel.transferIdToMessageIDs[transferID] == nil)
+    }
+
+    @Test @MainActor
+    func handleTransferEvent_cancelledRemovesOutgoingMessage() async {
+        let (viewModel, _) = makeTestableViewModel()
+        let peerID = PeerID(str: "1111111111111111111111111111111111111111111111111111111111111111")
+        let message = viewModel.enqueueMediaMessage(content: "[image] pic.jpg", targetPeer: peerID)
+        let transferID = "transfer-2"
+
+        viewModel.registerTransfer(transferId: transferID, messageID: message.id)
+        viewModel.handleTransferEvent(.cancelled(id: transferID, sentFragments: 1, totalFragments: 3))
+
+        #expect(viewModel.privateChats[peerID]?.contains(where: { $0.id == message.id }) != true)
+        #expect(viewModel.messageIDToTransferId[message.id] == nil)
+    }
+
+    @Test @MainActor
+    func sendVoiceNote_outsideAllowedContextDeletesTempFile() async throws {
+        let (viewModel, _) = makeTestableViewModel()
+        let geohash = "u4pruydq"
+        let url = FileManager.default.temporaryDirectory.appendingPathComponent("voice-\(UUID().uuidString).m4a")
+
+        try Data("voice".utf8).write(to: url)
+        viewModel.switchLocationChannel(to: .location(GeohashChannel(level: .city, geohash: geohash)))
+
+        viewModel.sendVoiceNote(at: url)
+
+        #expect(!FileManager.default.fileExists(atPath: url.path))
+        #expect(viewModel.messages.contains(where: { $0.sender == "system" }))
+    }
+
+    @Test @MainActor
+    func sendImage_outsideAllowedContextRunsCleanup() async {
+        let (viewModel, _) = makeTestableViewModel()
+        let geohash = "u4pruydq"
+        var cleanupCalled = false
+
+        viewModel.switchLocationChannel(to: .location(GeohashChannel(level: .city, geohash: geohash)))
+        viewModel.sendImage(from: URL(fileURLWithPath: "/tmp/ignored.jpg")) {
+            cleanupCalled = true
+        }
+
+        #expect(cleanupCalled)
+        #expect(viewModel.messages.contains(where: { $0.sender == "system" }))
+    }
+
+    @Test @MainActor
+    func sendVoiceNote_privateChatUsesPrivateFileTransfer() async throws {
+        let (viewModel, transport) = makeTestableViewModel()
+        let peerID = PeerID(str: "2222222222222222222222222222222222222222222222222222222222222222")
+        let url = FileManager.default.temporaryDirectory.appendingPathComponent("voice-\(UUID().uuidString).m4a")
+        try Data("voice payload".utf8).write(to: url, options: .atomic)
+        defer { try? FileManager.default.removeItem(at: url) }
+
+        viewModel.selectedPrivateChatPeer = peerID
+        viewModel.sendVoiceNote(at: url)
+
+        let didSend = await TestHelpers.waitUntil({ transport.sentPrivateFiles.count == 1 }, timeout: 0.5)
+        #expect(didSend)
+        #expect(transport.sentPrivateFiles.first?.peerID == peerID)
+        #expect(viewModel.privateChats[peerID]?.last?.content.contains("[voice]") == true)
+        #expect(viewModel.messageIDToTransferId.count == 1)
+        #expect(viewModel.transferIdToMessageIDs.count == 1)
+    }
+
+    @Test @MainActor
+    func sendVoiceNote_oversizedFileFailsAndDeletesTempFile() async throws {
+        let (viewModel, transport) = makeTestableViewModel()
+        let peerID = PeerID(str: "3333333333333333333333333333333333333333333333333333333333333333")
+        let url = FileManager.default.temporaryDirectory.appendingPathComponent("voice-too-large-\(UUID().uuidString).m4a")
+        try Data(repeating: 0x55, count: FileTransferLimits.maxVoiceNoteBytes + 1).write(to: url, options: .atomic)
+
+        viewModel.selectedPrivateChatPeer = peerID
+        viewModel.sendVoiceNote(at: url)
+
+        let didFail = await TestHelpers.waitUntil({
+            isFailed(status: viewModel.privateChats[peerID]?.last?.deliveryStatus)
+        }, timeout: 0.5)
+        #expect(didFail)
+        #expect(!FileManager.default.fileExists(atPath: url.path))
+        #expect(transport.sentPrivateFiles.isEmpty)
+    }
+
+    @Test @MainActor
+    func sendImage_privateChatProcessesAndTransfersImage() async throws {
+        let (viewModel, transport) = makeTestableViewModel()
+        let peerID = PeerID(str: "4444444444444444444444444444444444444444444444444444444444444444")
+        let sourceURL = try makeTemporaryImageURL()
+        defer { try? FileManager.default.removeItem(at: sourceURL) }
+
+        viewModel.selectedPrivateChatPeer = peerID
+        viewModel.sendImage(from: sourceURL)
+
+        let didSend = await TestHelpers.waitUntil({ transport.sentPrivateFiles.count == 1 }, timeout: 1.0)
+        #expect(didSend)
+        #expect(transport.sentPrivateFiles.first?.peerID == peerID)
+        #expect(transport.sentPrivateFiles.first?.packet.mimeType == "image/jpeg")
+        #expect(viewModel.privateChats[peerID]?.last?.content.contains("[image]") == true)
+        #expect(viewModel.messageIDToTransferId.count == 1)
+    }
+
+    @Test @MainActor
+    func sendImage_invalidSourceAddsFailureSystemMessage() async throws {
+        let (viewModel, transport) = makeTestableViewModel()
+        let peerID = PeerID(str: "5555555555555555555555555555555555555555555555555555555555555555")
+        let url = FileManager.default.temporaryDirectory.appendingPathComponent("invalid-\(UUID().uuidString).jpg")
+        try Data("not-an-image".utf8).write(to: url, options: .atomic)
+        defer { try? FileManager.default.removeItem(at: url) }
+
+        viewModel.selectedPrivateChatPeer = peerID
+        viewModel.sendImage(from: url)
+
+        let didNotify = await TestHelpers.waitUntil({
+            viewModel.messages.contains(where: { $0.sender == "system" && $0.content.contains("Failed to prepare image") })
+        }, timeout: 2.0)
+        #expect(didNotify)
+        #expect(transport.sentPrivateFiles.isEmpty)
+        #expect(viewModel.privateChats[peerID]?.isEmpty != false)
+    }
+
+    @Test @MainActor
+    func clearTransferMapping_promotesQueuedTransferForSameID() async {
+        let (viewModel, _) = makeTestableViewModel()
+        viewModel.registerTransfer(transferId: "transfer-queue", messageID: "first")
+        viewModel.registerTransfer(transferId: "transfer-queue", messageID: "second")
+
+        viewModel.clearTransferMapping(for: "first")
+
+        #expect(viewModel.messageIDToTransferId["first"] == nil)
+        #expect(viewModel.transferIdToMessageIDs["transfer-queue"] == ["second"])
+        #expect(viewModel.messageIDToTransferId["second"] == "transfer-queue")
+    }
+
+    @Test @MainActor
+    func cancelMediaSend_cancelsActiveTransferRemovesMessageAndDeletesFile() async throws {
+        let (viewModel, transport) = makeTestableViewModel()
+        let peerID = PeerID(str: "6666666666666666666666666666666666666666666666666666666666666666")
+        let fileName = "cancel-\(UUID().uuidString).m4a"
+        let fileURL = try mediaFileURL(subdirectory: "voicenotes/outgoing", fileName: fileName)
+        try Data("cancel me".utf8).write(to: fileURL, options: .atomic)
+
+        let message = BitchatMessage(
+            id: "cancel-msg",
+            sender: viewModel.nickname,
+            content: "[voice] \(fileName)",
+            timestamp: Date(),
+            isRelay: false,
+            isPrivate: true,
+            recipientNickname: "Peer",
+            senderPeerID: viewModel.meshService.myPeerID,
+            deliveryStatus: .sending
+        )
+        viewModel.privateChats[peerID] = [message]
+        viewModel.registerTransfer(transferId: "transfer-cancel", messageID: message.id)
+
+        viewModel.cancelMediaSend(messageID: message.id)
+
+        #expect(transport.cancelledTransfers == ["transfer-cancel"])
+        #expect(viewModel.privateChats[peerID] == nil)
+        #expect(!FileManager.default.fileExists(atPath: fileURL.path))
+    }
+
+    @Test @MainActor
+    func deleteMediaMessage_removesStoredMessageAndCleansImageFile() async throws {
+        let (viewModel, _) = makeTestableViewModel()
+        let peerID = PeerID(str: "7777777777777777777777777777777777777777777777777777777777777777")
+        let fileName = "delete-\(UUID().uuidString).jpg"
+        let fileURL = try mediaFileURL(subdirectory: "images/outgoing", fileName: fileName)
+        try Data("image bytes".utf8).write(to: fileURL, options: .atomic)
+
+        let message = BitchatMessage(
+            id: "delete-msg",
+            sender: viewModel.nickname,
+            content: "[image] \(fileName)",
+            timestamp: Date(),
+            isRelay: false,
+            isPrivate: true,
+            recipientNickname: "Peer",
+            senderPeerID: viewModel.meshService.myPeerID,
+            deliveryStatus: .sent
+        )
+        viewModel.privateChats[peerID] = [message]
+        viewModel.registerTransfer(transferId: "transfer-delete", messageID: message.id)
+
+        viewModel.deleteMediaMessage(messageID: message.id)
+
+        #expect(viewModel.privateChats[peerID] == nil)
+        #expect(viewModel.messageIDToTransferId[message.id] == nil)
+        #expect(!FileManager.default.fileExists(atPath: fileURL.path))
+    }
+
+    @Test @MainActor
+    func makeTransferID_isPrefixedByMessageIDAndUnique() async {
+        let (viewModel, _) = makeTestableViewModel()
+
+        let first = viewModel.makeTransferID(messageID: "base")
+        let second = viewModel.makeTransferID(messageID: "base")
+
+        #expect(first.hasPrefix("base-"))
+        #expect(second.hasPrefix("base-"))
+        #expect(first != second)
+    }
 }
 
 private func base64URLEncode(_ data: Data) -> String {
@@ -457,3 +1026,116 @@ private func base64URLEncode(_ data: Data) -> String {
         .replacingOccurrences(of: "/", with: "_")
         .replacingOccurrences(of: "=", with: "")
 }
+
+private func ackContent(type: NoisePayloadType, messageID: String, senderPeerID: PeerID) throws -> String {
+    if let content = NostrEmbeddedBitChat.encodeAckForNostrNoRecipient(
+        type: type,
+        messageID: messageID,
+        senderPeerID: senderPeerID
+    ) {
+        return content
+    }
+    throw ChatViewModelExtensionsTestError.invalidAckContent
+}
+
+private func privateMessageContent(text: String, messageID: String, senderPeerID: PeerID) throws -> String {
+    if let content = NostrEmbeddedBitChat.encodePMForNostrNoRecipient(
+        content: text,
+        messageID: messageID,
+        senderPeerID: senderPeerID
+    ) {
+        return content
+    }
+    throw ChatViewModelExtensionsTestError.invalidPrivateMessageContent
+}
+
+@MainActor
+private func deliveryStatus(in viewModel: ChatViewModel, peerID: PeerID, messageID: String) -> DeliveryStatus? {
+    viewModel.privateChats[peerID]?.first(where: { $0.id == messageID })?.deliveryStatus
+}
+
+private func isFailed(status: DeliveryStatus?) -> Bool {
+    if case .failed = status {
+        return true
+    }
+    return false
+}
+
+private func isDelivered(status: DeliveryStatus?) -> Bool {
+    if case .delivered = status {
+        return true
+    }
+    return false
+}
+
+private func isRead(status: DeliveryStatus?) -> Bool {
+    if case .read = status {
+        return true
+    }
+    return false
+}
+
+private func isSent(status: DeliveryStatus?) -> Bool {
+    if case .sent = status {
+        return true
+    }
+    return false
+}
+
+private func isPartiallyDelivered(status: DeliveryStatus?, reached: Int, total: Int) -> Bool {
+    if case .partiallyDelivered(let actualReached, let actualTotal) = status {
+        return actualReached == reached && actualTotal == total
+    }
+    return false
+}
+
+private enum ChatViewModelExtensionsTestError: Error {
+    case invalidAckContent
+    case invalidPrivateMessageContent
+}
+
+private func mediaFileURL(subdirectory: String, fileName: String) throws -> URL {
+    let base = try FileManager.default.url(
+        for: .applicationSupportDirectory,
+        in: .userDomainMask,
+        appropriateFor: nil,
+        create: true
+    ).appendingPathComponent("files", isDirectory: true)
+    let directory = base.appendingPathComponent(subdirectory, isDirectory: true)
+    try FileManager.default.createDirectory(at: directory, withIntermediateDirectories: true)
+    return directory.appendingPathComponent(fileName)
+}
+
+private func makeTemporaryImageURL() throws -> URL {
+    let url = FileManager.default.temporaryDirectory.appendingPathComponent("image-\(UUID().uuidString).png")
+    let data = try makeImageData()
+    try data.write(to: url, options: .atomic)
+    return url
+}
+
+private func makeImageData() throws -> Data {
+    #if os(iOS)
+    let image = UIGraphicsImageRenderer(size: CGSize(width: 64, height: 64)).image { context in
+        UIColor.systemTeal.setFill()
+        context.fill(CGRect(x: 0, y: 0, width: 64, height: 64))
+    }
+    guard let data = image.pngData() else {
+        throw ChatViewModelExtensionsTestError.invalidPrivateMessageContent
+    }
+    return data
+    #else
+    let image = NSImage(size: CGSize(width: 64, height: 64))
+    image.lockFocus()
+    NSColor.systemTeal.setFill()
+    NSBezierPath(rect: CGRect(x: 0, y: 0, width: 64, height: 64)).fill()
+    image.unlockFocus()
+    guard
+        let tiffData = image.tiffRepresentation,
+        let bitmap = NSBitmapImageRep(data: tiffData),
+        let data = bitmap.representation(using: .png, properties: [:])
+    else {
+        throw ChatViewModelExtensionsTestError.invalidPrivateMessageContent
+    }
+    return data
+    #endif
+}