Correlate private media delivery receipts

bitchat/Protocols/BitchatFilePacket.swift

@@ -154,3 +154,90 @@ struct BitchatFilePacket {
         )
     }
 }
+
+/// Wire-compatible identity for private media exchanged by clients using the
+/// current iOS entropy-bearing filenames, without extending the deployed file
+/// TLV. Android clients reject unknown file tags, so eligible senders and
+/// receivers derive the receipt key from fields already on the wire.
+///
+/// Locally-created image and voice-note filenames contain a UUID or live-voice
+/// burst ID. Including the normalized direction keeps a reused filename
+/// distinct across chats while allowing short and full Noise-key peer IDs to
+/// converge. Android and older-iOS timestamp-only names remain ineligible and
+/// retain their legacy random local IDs (transfer-compatible, no receipts).
+enum PrivateMediaMessageIdentity {
+    private static let domain = Data("bitchat-private-media-message-v1".utf8)
+    private static let idPrefix = "media-"
+    private static let digestHexLength = 32
+
+    static func isStableID(_ candidate: String) -> Bool {
+        guard candidate.hasPrefix(idPrefix) else { return false }
+        let digest = candidate.dropFirst(idPrefix.count)
+        guard digest.utf8.count == digestHexLength else { return false }
+        return digest.utf8.allSatisfy { byte in
+            (UInt8(ascii: "0")...UInt8(ascii: "9")).contains(byte)
+                || (UInt8(ascii: "a")...UInt8(ascii: "f")).contains(byte)
+        }
+    }
+
+    static func stableID(
+        senderPeerID: PeerID,
+        recipientPeerID: PeerID,
+        fileName: String?
+    ) -> String? {
+        guard let fileName, !fileName.isEmpty else { return nil }
+        let leafName = (fileName as NSString).lastPathComponent
+        guard leafName == fileName else { return nil }
+
+        let path = leafName as NSString
+        let stem = path.deletingPathExtension
+        let fileExtension = path.pathExtension.lowercased()
+        switch true {
+        case stem.hasPrefix("img_"):
+            guard fileExtension == "jpg" || fileExtension == "jpeg" else { return nil }
+        case stem.hasPrefix("voice_"):
+            guard fileExtension == "m4a" else { return nil }
+        default:
+            return nil
+        }
+        let entropyToken = stem.split(separator: "_").last.map(String.init)
+        let hasUUIDEntropy = entropyToken.flatMap(UUID.init(uuidString:)) != nil
+        let voiceBurstID = stem.hasPrefix("voice_")
+            ? String(stem.dropFirst("voice_".count))
+            : ""
+        let hasBurstEntropy = voiceBurstID.count == 16
+            && voiceBurstID.allSatisfy(\.isHexDigit)
+        guard hasUUIDEntropy || hasBurstEntropy else {
+            return nil
+        }
+
+        let fields = [
+            Data(senderPeerID.toShort().bare.utf8),
+            Data(recipientPeerID.toShort().bare.utf8),
+            Data(leafName.utf8)
+        ]
+        var input = domain
+        for field in fields {
+            guard let length = UInt32(exactly: field.count) else { return nil }
+            var bigEndianLength = length.bigEndian
+            withUnsafeBytes(of: &bigEndianLength) {
+                input.append(contentsOf: $0)
+            }
+            input.append(field)
+        }
+
+        return "\(idPrefix)\(input.sha256Hex().prefix(digestHexLength))"
+    }
+
+    static func stableID(
+        for packet: BitchatFilePacket,
+        senderPeerID: PeerID,
+        recipientPeerID: PeerID
+    ) -> String? {
+        stableID(
+            senderPeerID: senderPeerID,
+            recipientPeerID: recipientPeerID,
+            fileName: packet.fileName
+        )
+    }
+}

bitchat/Services/BLE/BLEFileTransferHandler.swift

@@ -32,17 +32,63 @@ struct BLEFileTransferHandlerEnvironment {
         _ fallbackExtension: String?,
         _ defaultPrefix: String
     ) -> URL?
+    /// Checks the authenticated sender before any private-media disk work.
+    let isPrivateMediaSenderBlocked: (PeerID) -> Bool
     /// Updates the registry last-seen timestamp for the peer (async barrier write).
     let updatePeerLastSeen: (PeerID) -> Void
+    /// Re-acknowledges a stable private-media duplicate without saving or
+    /// re-delivering it. This lets a sender recover from a lost ACK.
+    let acknowledgePrivateMediaDuplicate: (_ messageID: String, _ peerID: PeerID) -> Void
     /// Delivers `.messageReceived` to the UI as one main-actor hop.
     let deliverMessage: (BitchatMessage) -> Void
 }
 
+/// Process-lifetime reservation cache for stable private-media IDs.
+///
+/// The first arrival reserves its ID before quota enforcement and commits it
+/// only after durable save. Concurrent/retried arrivals are rejected before
+/// they can create uniquified orphan files or churn the incoming-media quota.
+private final class PrivateMediaArrivalDeduplicator {
+    enum Reservation {
+        case reserved
+        case pending
+        case accepted
+    }
+
+    private let lock = NSLock()
+    private var accepted = BoundedIDSet(capacity: 4_096)
+    private var pending: Set<String> = []
+
+    func reserve(_ messageID: String) -> Reservation {
+        lock.lock()
+        defer { lock.unlock() }
+        if accepted.contains(messageID) {
+            return .accepted
+        }
+        if pending.contains(messageID) {
+            return .pending
+        }
+
+        pending.insert(messageID)
+        return .reserved
+    }
+
+    func finish(_ messageID: String, accepted didAccept: Bool) {
+        lock.lock()
+        defer { lock.unlock() }
+        pending.remove(messageID)
+        if didAccept {
+            accepted.insert(messageID)
+        }
+    }
+}
+
 /// Orchestrates inbound file transfers: self-echo policy, sender display-name
 /// resolution, delivery planning, payload validation, quota-checked storage,
 /// and UI delivery.
 final class BLEFileTransferHandler {
     private let environment: BLEFileTransferHandlerEnvironment
+    private let privateMediaArrivals = PrivateMediaArrivalDeduplicator()
 
     init(environment: BLEFileTransferHandlerEnvironment) {
         self.environment = environment
@@ -129,6 +175,7 @@ final class BLEFileTransferHandler {
         env: BLEFileTransferHandlerEnvironment
     ) -> Bool {
 
+        let localPeerID = env.localPeerID()
         let filePacket: BitchatFilePacket
         let mime: MimeType
         switch BLEIncomingFileValidator.validate(payload: payload) {
@@ -149,6 +196,51 @@ final class BLEFileTransferHandler {
             return false
         }
 
+        if isPrivate, env.isPrivateMediaSenderBlocked(peerID) {
+            SecureLogger.debug(
+                "🚫 Dropping private media from blocked peer \(peerID.id.prefix(8))… before disk write",
+                category: .security
+            )
+            return true
+        }
+
+        let messageID = isPrivate
+            ? PrivateMediaMessageIdentity.stableID(
+                for: filePacket,
+                senderPeerID: peerID,
+                recipientPeerID: localPeerID
+            )
+            : nil
+        if let messageID {
+            switch privateMediaArrivals.reserve(messageID) {
+            case .reserved:
+                break
+            case .pending:
+                // The first arrival has not reached durable storage yet.
+                // Coalesce this retry without ACKing so a failed first save
+                // remains retryable by the sender.
+                SecureLogger.debug(
+                    "📁 Coalesced in-flight private media id=\(messageID.prefix(12))… from \(peerID.id.prefix(8))…",
+                    category: .session
+                )
+                return true
+            case .accepted:
+                env.updatePeerLastSeen(peerID)
+                env.acknowledgePrivateMediaDuplicate(messageID, peerID)
+                SecureLogger.debug(
+                    "📁 Ignored durable private media duplicate id=\(messageID.prefix(12))… from \(peerID.id.prefix(8))…",
+                    category: .session
+                )
+                return true
+            }
+        }
+        var acceptedStableMedia = false
+        defer {
+            if let messageID {
+                privateMediaArrivals.finish(messageID, accepted: acceptedStableMedia)
+            }
+        }
+
         // BCH-01-002: Enforce storage quota before saving
         env.enforceStorageQuota(filePacket.content.count)
 
@@ -167,6 +259,7 @@ final class BLEFileTransferHandler {
         }
 
         let message = BitchatMessage(
+            id: messageID,
             sender: senderNickname,
             content: "\(mime.category.messagePrefix)\(destination.lastPathComponent)",
             timestamp: timestamp,
@@ -185,6 +278,7 @@ final class BLEFileTransferHandler {
 
         SecureLogger.debug("📁 Stored incoming media from \(peerID.id.prefix(8))… -> \(destination.lastPathComponent)", category: .session)
 
+        acceptedStableMedia = messageID != nil
         env.deliverMessage(message)
         return true
     }

bitchat/Services/BLE/BLEService.swift

@@ -2342,9 +2342,30 @@ final class BLEService: NSObject {
                     defaultPrefix: defaultPrefix
                 )
             },
+            isPrivateMediaSenderBlocked: { [weak self] peerID in
+                guard let self else { return false }
+                let senderStaticKey = self.noiseService.getPeerPublicKeyData(peerID)
+                    ?? self.collectionsQueue.sync {
+                        self.peerRegistry.info(for: peerID)?.noisePublicKey
+                    }
+                guard let senderStaticKey else { return false }
+                return self.identityManager.isBlocked(
+                    fingerprint: senderStaticKey.sha256Fingerprint()
+                )
+            },
             updatePeerLastSeen: { [weak self] peerID in
                 self?.updatePeerLastSeen(peerID)
             },
+            acknowledgePrivateMediaDuplicate: { [weak self] messageID, peerID in
+                guard let self,
+                      let senderStaticKey = self.noiseService.getPeerPublicKeyData(peerID),
+                      !self.identityManager.isBlocked(
+                        fingerprint: senderStaticKey.sha256Fingerprint()
+                      ) else {
+                    return
+                }
+                self.sendDeliveryAck(for: messageID, to: peerID)
+            },
             deliverMessage: { [weak self] message in
                 // Single main-actor hop delivering `.messageReceived`.
                 self?.emitTransportEvent(.messageReceived(message))

bitchat/ViewModels/ChatLiveVoiceCoordinator.swift

@@ -10,6 +10,7 @@ import Foundation
 @MainActor
 protocol ChatLiveVoiceContext: AnyObject {
     var nickname: String { get }
+    var myPeerID: PeerID { get }
     var selectedPrivateChatPeer: PeerID? { get }
     /// Whether the public mesh timeline is what's on screen (autoplay gate
     /// for public bursts).
@@ -30,6 +31,12 @@ protocol ChatLiveVoiceContext: AnyObject {
     func upsertPublicMeshMessage(_ message: BitchatMessage)
     @discardableResult
     func removePrivateMessage(withID messageID: String) -> BitchatMessage?
+    /// Records and sends the finalized note's read receipt after a live
+    /// bubble adopts its wire-derivable message ID.
+    func hasSentReadReceipt(_ messageID: String) -> Bool
+    @discardableResult
+    func markReadReceiptSent(_ messageID: String) -> Bool
+    func sendMeshReadReceipt(_ receipt: ReadReceipt, to peerID: PeerID)
     /// Removes a message from whichever conversation holds it.
     func removeMessage(withID messageID: String, cleanupFile: Bool)
     /// Publishes who is currently talking live in the public mesh channel
@@ -257,8 +264,16 @@ final class ChatLiveVoiceCoordinator {
         guard let entry = finishedBursts.first(where: { matches($0.key) }) else { return false }
         let finished = entry.value
 
+        // A DM live bubble starts before the finalized file exists and
+        // therefore has a receiver-local random ID. Adopt the finalized
+        // message's deterministic ID so delivery/read ACKs address the same
+        // row as the sender's media placeholder. Public notes retain their
+        // live-bubble ID because public transfers have no private receipts.
+        let replacementID = finished.scope == .directMessage
+            ? message.id
+            : finished.messageID
         let replacement = BitchatMessage(
-            id: finished.messageID,
+            id: replacementID,
             sender: message.sender,
             content: message.content,
             timestamp: finished.messageTimestamp,
@@ -272,7 +287,31 @@ final class ChatLiveVoiceCoordinator {
         )
         switch finished.scope {
         case .directMessage:
+            // Capture read state before rekeying. The user may have read the
+            // live bubble and navigated away before the finalized .m4a lands.
+            let shouldSendAdoptedReadReceipt =
+                context.hasSentReadReceipt(finished.messageID)
+                || context.selectedPrivateChatPeer == finished.peerID
+
+            // Insert first so replacing the only row in a DM never
+            // transiently deletes its conversation, unread state, or current
+            // selection. Then remove the receiver-local live-bubble alias.
             context.upsertPrivateMessage(replacement, in: finished.peerID)
+            if replacementID != finished.messageID {
+                context.removePrivateMessage(withID: finished.messageID)
+            }
+            // The live bubble may already have emitted a receiver-local READ
+            // before the sender created its finalized media row. Re-emit once
+            // for the adopted stable ID now that the file has arrived.
+            if shouldSendAdoptedReadReceipt,
+               context.markReadReceiptSent(replacementID) {
+                let receipt = ReadReceipt(
+                    originalMessageID: replacementID,
+                    readerID: context.myPeerID,
+                    readerNickname: context.nickname
+                )
+                context.sendMeshReadReceipt(receipt, to: finished.peerID)
+            }
         case .publicMesh:
             context.upsertPublicMeshMessage(replacement)
         }

bitchat/ViewModels/ChatMediaTransferCoordinator.swift

@@ -171,9 +171,17 @@ final class ChatMediaTransferCoordinator {
         }
 
         let targetPeer = context.selectedPrivateChatPeer
+        let privateMessageID = targetPeer.flatMap { peerID in
+            PrivateMediaMessageIdentity.stableID(
+                senderPeerID: context.myPeerID,
+                recipientPeerID: peerID,
+                fileName: url.lastPathComponent
+            )
+        }
         let message = enqueueMediaMessage(
             content: "\(MimeType.Category.audio.messagePrefix)\(url.lastPathComponent)",
-            targetPeer: targetPeer
+            targetPeer: targetPeer,
+            messageID: privateMessageID
         )
         let messageID = message.id
         let transferId = makeTransferID(messageID: messageID)
@@ -282,9 +290,17 @@ final class ChatMediaTransferCoordinator {
 
                 await MainActor.run { [weak self] in
                     guard let self else { return }
+                    let privateMessageID = targetPeer.flatMap { peerID in
+                        PrivateMediaMessageIdentity.stableID(
+                            for: prepared.packet,
+                            senderPeerID: self.context.myPeerID,
+                            recipientPeerID: peerID
+                        )
+                    }
                     let message = self.enqueueMediaMessage(
                         content: "\(MimeType.Category.image.messagePrefix)\(prepared.outputURL.lastPathComponent)",
-                        targetPeer: targetPeer
+                        targetPeer: targetPeer,
+                        messageID: privateMessageID
                     )
                     let messageID = message.id
                     let transferId = self.makeTransferID(messageID: messageID)
@@ -316,12 +332,17 @@ final class ChatMediaTransferCoordinator {
         }
     }
 
-    func enqueueMediaMessage(content: String, targetPeer: PeerID?) -> BitchatMessage {
+    func enqueueMediaMessage(
+        content: String,
+        targetPeer: PeerID?,
+        messageID: String? = nil
+    ) -> BitchatMessage {
         let timestamp = Date()
         let message: BitchatMessage
 
         if let peerID = targetPeer {
             message = BitchatMessage(
+                id: messageID,
                 sender: context.nickname,
                 content: content,
                 timestamp: timestamp,

bitchat/ViewModels/ChatViewModel.swift

@@ -467,6 +467,12 @@ final class ChatViewModel: ObservableObject, BitchatDelegate, SynchronousMessage
         }
     }
 
+    /// Whether a read receipt has already been recorded for `messageID`.
+    @MainActor
+    func hasSentReadReceipt(_ messageID: String) -> Bool {
+        sentReadReceipts.contains(messageID)
+    }
+
     /// Records that a read receipt is being sent for `messageID`.
     /// Returns `false` when one was already recorded — the caller must skip sending.
     @MainActor

bitchatTests/ChatLiveVoiceCoordinatorTests.swift

@@ -14,6 +14,7 @@ import BitFoundation
 @MainActor
 private final class MockChatLiveVoiceContext: ChatLiveVoiceContext {
     var nickname = "me"
+    var myPeerID = PeerID(str: "0102030405060708")
     var selectedPrivateChatPeer: PeerID?
     var isViewingPublicMeshTimeline = false
     var blockedPeers: Set<PeerID> = []
@@ -23,7 +24,10 @@ private final class MockChatLiveVoiceContext: ChatLiveVoiceContext {
     private(set) var upsertedMessages: [(message: BitchatMessage, peerID: PeerID)] = []
     private(set) var upsertedPublicMessages: [BitchatMessage] = []
     private(set) var removedMessageIDs: [String] = []
+    private(set) var sentReadReceipts: [(receipt: ReadReceipt, peerID: PeerID)] = []
     private(set) var talkerUpdates: [String?] = []
+    private(set) var privateMutationLog: [String] = []
+    private var readReceiptMessageIDs: Set<String> = []
 
     func isPeerBlocked(_ peerID: PeerID) -> Bool { blockedPeers.contains(peerID) }
     func resolveNickname(for peerID: PeerID) -> String { "alice" }
@@ -31,6 +35,7 @@ private final class MockChatLiveVoiceContext: ChatLiveVoiceContext {
     func appendPublicMeshMessage(_ message: BitchatMessage) { appendedPublicMessages.append(message) }
     func upsertPrivateMessage(_ message: BitchatMessage, in peerID: PeerID) {
         upsertedMessages.append((message, peerID))
+        privateMutationLog.append("upsert:\(message.id)")
     }
     func upsertPublicMeshMessage(_ message: BitchatMessage) {
         upsertedPublicMessages.append(message)
@@ -38,8 +43,18 @@ private final class MockChatLiveVoiceContext: ChatLiveVoiceContext {
     @discardableResult
     func removePrivateMessage(withID messageID: String) -> BitchatMessage? {
         removedMessageIDs.append(messageID)
+        privateMutationLog.append("remove:\(messageID)")
         return nil
     }
+    func hasSentReadReceipt(_ messageID: String) -> Bool {
+        readReceiptMessageIDs.contains(messageID)
+    }
+    func markReadReceiptSent(_ messageID: String) -> Bool {
+        readReceiptMessageIDs.insert(messageID).inserted
+    }
+    func sendMeshReadReceipt(_ receipt: ReadReceipt, to peerID: PeerID) {
+        sentReadReceipts.append((receipt, peerID))
+    }
     func removeMessage(withID messageID: String, cleanupFile: Bool) {
         removedMessageIDs.append(messageID)
     }
@@ -151,17 +166,29 @@ struct ChatLiveVoiceCoordinatorTests {
 
     @Test func absorbsFinalizedNoteIntoLiveBubble() throws {
         let context = MockChatLiveVoiceContext()
+        context.selectedPrivateChatPeer = peer
         let coordinator = ChatLiveVoiceCoordinator(context: context, sweepsOnInit: false)
         let burstID = makeBurstID(0xB2)
         let hex = burstID.hexEncodedString()
+        let fileName = "voice_\(hex).m4a"
+        let stableMessageID = try #require(PrivateMediaMessageIdentity.stableID(
+            senderPeerID: peer,
+            recipientPeerID: context.myPeerID,
+            fileName: fileName
+        ))
 
         send(try #require(VoiceBurstPacket(burstID: burstID, seq: 1, kind: .frames([Data(repeating: 7, count: 50)]))), to: coordinator, from: peer)
         send(try #require(VoiceBurstPacket(burstID: burstID, seq: 2, kind: .end(totalDataPackets: 1, durationMs: 64))), to: coordinator, from: peer)
         let bubble = try #require(context.handledPrivateMessages.first)
+        // The user read the live bubble, then left before the finalized file
+        // arrived. Stable-ID adoption must preserve that read state.
+        #expect(context.markReadReceiptSent(bubble.id))
+        context.selectedPrivateChatPeer = nil
 
         let note = BitchatMessage(
+            id: stableMessageID,
             sender: "alice",
-            content: "[voice] voice_\(hex).m4a",
+            content: "[voice] \(fileName)",
             timestamp: Date(),
             isRelay: false,
             isPrivate: true,
@@ -170,12 +197,21 @@ struct ChatLiveVoiceCoordinatorTests {
         )
         #expect(coordinator.absorbFinalizedVoiceNote(note))
 
-        // The note replaced the live bubble in place: same message ID, new
+        // The finalized note adopts the sender-correlatable ID, removes the
-        // content, partial capture deleted.
+        // receiver-local live ID, and emits a fresh READ now that the sender
+        // has created its finalized media row.
         let replacement = try #require(context.upsertedMessages.last)
-        #expect(replacement.message.id == bubble.id)
+        #expect(replacement.message.id == stableMessageID)
         #expect(replacement.message.content == note.content)
         #expect(replacement.peerID == peer)
+        #expect(context.removedMessageIDs.contains(bubble.id))
+        #expect(Array(context.privateMutationLog.suffix(2)) == [
+            "upsert:\(stableMessageID)",
+            "remove:\(bubble.id)"
+        ])
+        #expect(context.sentReadReceipts.count == 1)
+        #expect(context.sentReadReceipts.first?.receipt.originalMessageID == stableMessageID)
+        #expect(context.sentReadReceipts.first?.peerID == peer)
         // The promoted partial capture is deleted in favor of the note.
         let url = try #require(fallbackFileURL(burstID: burstID, peerID: peer))
         #expect(!FileManager.default.fileExists(atPath: url.path))
@@ -449,7 +485,8 @@ struct ChatLiveVoiceCoordinatorTests {
             isRelay: false, isPrivate: true, recipientNickname: "me", senderPeerID: peer
         )
         #expect(coordinator.absorbFinalizedVoiceNote(dmNote))
-        #expect(try #require(context.upsertedMessages.last).message.id == dmBubble.id)
+        #expect(try #require(context.upsertedMessages.last).message.id == dmNote.id)
+        #expect(context.removedMessageIDs.contains(dmBubble.id))
     }
 
     @Test func finalizedNoteBindsToItsAuthenticatedSender() throws {
@@ -479,8 +516,9 @@ struct ChatLiveVoiceCoordinatorTests {
         )
         #expect(coordinator.absorbFinalizedVoiceNote(note))
         let replacement = try #require(context.upsertedMessages.last)
-        #expect(replacement.message.id == victimBubble.id)
+        #expect(replacement.message.id == note.id)
         #expect(replacement.peerID == peer)
+        #expect(context.removedMessageIDs.contains(victimBubble.id))
 
         // The attacker's note can only ever claim the attacker's own bubble.
         let attackerNote = BitchatMessage(
@@ -489,8 +527,9 @@ struct ChatLiveVoiceCoordinatorTests {
         )
         #expect(coordinator.absorbFinalizedVoiceNote(attackerNote))
         let attackerReplacement = try #require(context.upsertedMessages.last)
-        #expect(attackerReplacement.message.id == attackerBubble.id)
+        #expect(attackerReplacement.message.id == attackerNote.id)
         #expect(attackerReplacement.peerID == attacker)
+        #expect(context.removedMessageIDs.contains(attackerBubble.id))
 
         // Both registry entries are consumed — nothing left to hijack.
         #expect(!coordinator.absorbFinalizedVoiceNote(note))

bitchatTests/ChatMediaTransferCoordinatorContextTests.swift

@@ -15,6 +15,11 @@
 import Testing
 import Foundation
 import BitFoundation
+#if os(iOS)
+import UIKit
+#else
+import AppKit
+#endif
 @testable import bitchat
 
 // MARK: - Mock Context
@@ -84,7 +89,11 @@ private final class MockChatMediaTransferContext: ChatMediaTransferContext {
     }
 
     // Mesh file transfer
-    private(set) var privateFileSends: [(peerID: PeerID, transferId: String)] = []
+    private(set) var privateFileSends: [(
+        packet: BitchatFilePacket,
+        peerID: PeerID,
+        transferId: String
+    )] = []
     private(set) var privateFileLegacyAllowances: [Bool] = []
     private(set) var broadcastFileSends: [String] = []
     private(set) var cancelledTransfers: [String] = []
@@ -149,7 +158,7 @@ private final class MockChatMediaTransferContext: ChatMediaTransferContext {
         transferId: String,
         allowLegacyFallback: Bool
     ) {
-        privateFileSends.append((peerID, transferId))
+        privateFileSends.append((packet, peerID, transferId))
         privateFileLegacyAllowances.append(allowLegacyFallback)
     }
 
@@ -167,19 +176,8 @@ private final class PausedVoiceNotePreparer: @unchecked Sendable {
     private var started = false
     private var released = false
     private var finished = false
-    private let packet: BitchatFilePacket
 
-    init() {
+    func prepare(_ url: URL) throws -> BitchatFilePacket {
-        let content = Data("voice".utf8)
-        packet = BitchatFilePacket(
-            fileName: "paused.m4a",
-            fileSize: UInt64(content.count),
-            mimeType: "audio/mp4",
-            content: content
-        )
-    }
-
-    func prepare(_: URL) throws -> BitchatFilePacket {
         condition.lock()
         started = true
         condition.broadcast()
@@ -189,7 +187,13 @@ private final class PausedVoiceNotePreparer: @unchecked Sendable {
         finished = true
         condition.broadcast()
         condition.unlock()
-        return packet
+        let content = Data("voice".utf8)
+        return BitchatFilePacket(
+            fileName: url.lastPathComponent,
+            fileSize: UInt64(content.count),
+            mimeType: "audio/mp4",
+            content: content
+        )
     }
 
     var hasStarted: Bool {
@@ -339,6 +343,57 @@ struct ChatMediaTransferCoordinatorContextTests {
         #expect(coordinator.transferIdToMessageIDs.isEmpty)
     }
 
+    @Test @MainActor
+    func privateVoiceNoteUsesWireDerivableMessageID() async throws {
+        let context = MockChatMediaTransferContext()
+        let coordinator = ChatMediaTransferCoordinator(context: context)
+        let peerID = PeerID(str: "1122334455667788")
+        context.selectedPrivateChatPeer = peerID
+        let url = FileManager.default.temporaryDirectory
+            .appendingPathComponent("voice_receipt_\(UUID().uuidString).m4a")
+        try Data("voice".utf8).write(to: url)
+        defer { try? FileManager.default.removeItem(at: url) }
+
+        coordinator.sendVoiceNote(at: url)
+
+        #expect(await TestHelpers.waitUntil(
+            { context.privateFileSends.count == 1 },
+            timeout: TestConstants.longTimeout
+        ))
+        let message = try #require(context.privateChats[peerID]?.first)
+        let sentPacket = try #require(context.privateFileSends.first?.packet)
+        #expect(message.id == PrivateMediaMessageIdentity.stableID(
+            for: sentPacket,
+            senderPeerID: context.myPeerID,
+            recipientPeerID: peerID
+        ))
+    }
+
+    @Test @MainActor
+    func privateImageUsesWireDerivableMessageID() async throws {
+        let context = MockChatMediaTransferContext()
+        let coordinator = ChatMediaTransferCoordinator(context: context)
+        let peerID = PeerID(str: "99aabbccddeeff00")
+        context.selectedPrivateChatPeer = peerID
+        let sourceURL = try makeCoordinatorTestImageURL()
+        defer { try? FileManager.default.removeItem(at: sourceURL) }
+
+        coordinator.sendImage(from: sourceURL)
+
+        #expect(await TestHelpers.waitUntil(
+            { context.privateFileSends.count == 1 },
+            timeout: TestConstants.longTimeout
+        ))
+        let message = try #require(context.privateChats[peerID]?.first)
+        let sentPacket = try #require(context.privateFileSends.first?.packet)
+        #expect(message.id == PrivateMediaMessageIdentity.stableID(
+            for: sentPacket,
+            senderPeerID: context.myPeerID,
+            recipientPeerID: peerID
+        ))
+        coordinator.cleanupLocalFile(forMessage: message)
+    }
+
     @Test @MainActor
     func cancelVoiceNoteDuringDetachedPreparationCannotSendOrRestoreMapping() async throws {
         let context = MockChatMediaTransferContext()
@@ -584,3 +639,35 @@ struct ChatMediaTransferCoordinatorContextTests {
         #expect(context.privateFileSends.isEmpty)
     }
 }
+
+private func makeCoordinatorTestImageURL() throws -> URL {
+    let url = FileManager.default.temporaryDirectory
+        .appendingPathComponent("media-receipt-\(UUID().uuidString).png")
+    #if os(iOS)
+    let renderer = UIGraphicsImageRenderer(size: CGSize(width: 32, height: 32))
+    let image = renderer.image { context in
+        UIColor.systemBlue.setFill()
+        context.fill(CGRect(x: 0, y: 0, width: 32, height: 32))
+    }
+    guard let data = image.pngData() else {
+        throw CoordinatorMediaTestError.imageEncodingFailed
+    }
+    #else
+    let image = NSImage(size: NSSize(width: 32, height: 32))
+    image.lockFocus()
+    NSColor.systemBlue.setFill()
+    NSRect(x: 0, y: 0, width: 32, height: 32).fill()
+    image.unlockFocus()
+    guard let tiff = image.tiffRepresentation,
+          let bitmap = NSBitmapImageRep(data: tiff),
+          let data = bitmap.representation(using: .png, properties: [:]) else {
+        throw CoordinatorMediaTestError.imageEncodingFailed
+    }
+    #endif
+    try data.write(to: url, options: .atomic)
+    return url
+}
+
+private enum CoordinatorMediaTestError: Error {
+    case imageEncodingFailed
+}

bitchatTests/ChatTransportEventCoordinatorContextTests.swift

@@ -220,26 +220,64 @@ struct ChatTransportEventCoordinatorContextTests {
     func didReceiveMessage_routesPrivateAndPublic_skipsBlockedAndEmpty() async {
         let context = MockChatTransportEventContext()
         let coordinator = ChatTransportEventCoordinator(context: context)
+        let peerID = PeerID(str: "1122334455667788")
 
         // Blocked messages are dropped before any handling.
-        context.blockedMessageIDs = ["blocked"]
+        context.blockedMessageIDs = ["blocked", "blocked-private"]
         coordinator.didReceiveMessage(makeMessage(id: "blocked"))
+        coordinator.didReceiveMessage(makeMessage(
+            id: "blocked-private",
+            isPrivate: true,
+            senderPeerID: peerID
+        ))
         // Empty public content is dropped too.
         coordinator.didReceiveMessage(makeMessage(id: "empty", content: "   "))
         await drainMainActorTasks()
         #expect(context.handledPublicMessages.isEmpty)
         #expect(context.handledPrivateMessages.isEmpty)
         #expect(context.mentionCheckedMessageIDs.isEmpty)
+        #expect(context.meshDeliveryAcks.isEmpty)
 
         // Private goes to the private handler, public to the public handler;
-        // both get mention checks and haptics.
+        // both get mention checks and haptics. Only current-iOS media with a
-        coordinator.didReceiveMessage(makeMessage(id: "pm", isPrivate: true))
+        // cross-device stable ID and authenticated sender gets the
+        // durable-arrival acknowledgement. Legacy/Android-style random IDs
+        // remain transfer-compatible but cannot correlate receipts.
+        let stableMediaID = "media-\(String(repeating: "a", count: 32))"
+        coordinator.didReceiveMessage(makeMessage(
+            id: stableMediaID,
+            isPrivate: true,
+            senderPeerID: peerID
+        ))
+        coordinator.didReceiveMessage(makeMessage(
+            id: "legacy-media",
+            isPrivate: true,
+            senderPeerID: peerID
+        ))
+        coordinator.didReceiveMessage(makeMessage(id: "pm-missing-sender", isPrivate: true))
         coordinator.didReceiveMessage(makeMessage(id: "pub"))
         await drainMainActorTasks()
-        #expect(context.handledPrivateMessages.map(\.id) == ["pm"])
+        #expect(context.handledPrivateMessages.map(\.id) == [
+            stableMediaID,
+            "legacy-media",
+            "pm-missing-sender"
+        ])
         #expect(context.handledPublicMessages.map(\.id) == ["pub"])
-        #expect(context.mentionCheckedMessageIDs == ["pm", "pub"])
+        #expect(context.mentionCheckedMessageIDs == [
-        #expect(context.hapticMessageIDs == ["pm", "pub"])
+            stableMediaID,
+            "legacy-media",
+            "pm-missing-sender",
+            "pub"
+        ])
+        #expect(context.hapticMessageIDs == [
+            stableMediaID,
+            "legacy-media",
+            "pm-missing-sender",
+            "pub"
+        ])
+        #expect(context.meshDeliveryAcks.count == 1)
+        #expect(context.meshDeliveryAcks.first?.messageID == stableMediaID)
+        #expect(context.meshDeliveryAcks.first?.peerID == peerID)
     }
 
     @Test @MainActor

bitchatTests/EndToEnd/PrivateMediaEndToEndTests.swift

@@ -736,7 +736,7 @@ struct PrivateMediaEndToEndTests {
             + marker
             + Data(repeating: 0x4A, count: 6 * 1024)
         try await assertPrivateMediaRoundTrip(
-            fileName: "private.jpg",
+            fileName: "img_20260725_120000_11111111-1111-1111-1111-111111111111.jpg",
             mimeType: "image/jpeg",
             content: content,
             marker: marker,
@@ -1007,6 +1007,17 @@ struct PrivateMediaEndToEndTests {
         #expect(message.isPrivate)
         #expect(message.senderPeerID == alice.myPeerID)
         #expect(message.content.hasPrefix(expectedMessagePrefix))
+        if let stableMessageID = PrivateMediaMessageIdentity.stableID(
+            for: file,
+            senderPeerID: alice.myPeerID,
+            recipientPeerID: bob.myPeerID
+        ) {
+            #expect(message.id == stableMessageID)
+        } else {
+            // Generic/legacy filenames retain random per-arrival IDs so two
+            // unrelated "photo.jpg" transfers are never deduplicated.
+            #expect(!message.id.hasPrefix("media-"))
+        }
 
         let stored = recursivelyStoredFiles(under: bobRoot)
         #expect(stored.count == 1)

bitchatTests/Protocols/BitchatFilePacketTests.swift

@@ -1,3 +1,4 @@
+import BitFoundation
 import XCTest
 @testable import bitchat
 
@@ -73,4 +74,85 @@ final class BitchatFilePacketTests: XCTestCase {
         XCTAssertEqual(decoded.fileSize, UInt64(content.count))
         XCTAssertEqual(decoded.content, content)
     }
+
+    func testPrivateMediaMessageIdentityConvergesAcrossPeerIDAliases() throws {
+        let senderKey = Data(repeating: 0x11, count: 32)
+        let recipientKey = Data(repeating: 0x22, count: 32)
+        let senderStable = PeerID(hexData: senderKey)
+        let recipientStable = PeerID(hexData: recipientKey)
+        let fileName = "img_20260725_105708_1CC2760D-76AA-40C3-8013-C7FAA6C2EF99.jpg"
+
+        let senderID = try XCTUnwrap(PrivateMediaMessageIdentity.stableID(
+            senderPeerID: senderStable.toShort(),
+            recipientPeerID: PeerID(str: "mesh:\(recipientStable.toShort().bare)"),
+            fileName: fileName
+        ))
+        let receiverID = try XCTUnwrap(PrivateMediaMessageIdentity.stableID(
+            senderPeerID: senderStable,
+            recipientPeerID: recipientStable.toShort(),
+            fileName: fileName
+        ))
+
+        XCTAssertEqual(senderID, receiverID)
+        XCTAssertTrue(senderID.hasPrefix("media-"))
+        XCTAssertEqual(senderID.count, 38)
+        XCTAssertTrue(PrivateMediaMessageIdentity.isStableID(senderID))
+        XCTAssertFalse(PrivateMediaMessageIdentity.isStableID("media-\(String(repeating: "A", count: 32))"))
+        XCTAssertFalse(PrivateMediaMessageIdentity.isStableID("media-\(String(repeating: "a", count: 31))"))
+        XCTAssertFalse(PrivateMediaMessageIdentity.isStableID(UUID().uuidString))
+    }
+
+    func testPrivateMediaMessageIdentitySeparatesDirectionAndFilename() throws {
+        let alice = PeerID(str: "0011223344556677")
+        let bob = PeerID(str: "8899aabbccddeeff")
+        let firstName = "voice_20260725_105708_11111111-1111-1111-1111-111111111111.m4a"
+        let secondName = "voice_20260725_105709_22222222-2222-2222-2222-222222222222.m4a"
+        let first = try XCTUnwrap(PrivateMediaMessageIdentity.stableID(
+            senderPeerID: alice,
+            recipientPeerID: bob,
+            fileName: firstName
+        ))
+
+        XCTAssertNotEqual(first, PrivateMediaMessageIdentity.stableID(
+            senderPeerID: bob,
+            recipientPeerID: alice,
+            fileName: firstName
+        ))
+        XCTAssertNotEqual(first, PrivateMediaMessageIdentity.stableID(
+            senderPeerID: alice,
+            recipientPeerID: bob,
+            fileName: secondName
+        ))
+        XCTAssertNil(PrivateMediaMessageIdentity.stableID(
+            senderPeerID: alice,
+            recipientPeerID: bob,
+            fileName: nil
+        ))
+        XCTAssertNil(PrivateMediaMessageIdentity.stableID(
+            senderPeerID: alice,
+            recipientPeerID: bob,
+            fileName: "photo.jpg"
+        ))
+        XCTAssertNil(PrivateMediaMessageIdentity.stableID(
+            senderPeerID: alice,
+            recipientPeerID: bob,
+            fileName: "img_11111111-1111-1111-1111-111111111111.pdf"
+        ))
+        XCTAssertNotNil(PrivateMediaMessageIdentity.stableID(
+            senderPeerID: alice,
+            recipientPeerID: bob,
+            fileName: "voice_0011223344556677.m4a"
+        ))
+    }
+
+    func testPrivateMediaMessageIdentityMatchesVersionOneGoldenVector() {
+        XCTAssertEqual(
+            PrivateMediaMessageIdentity.stableID(
+                senderPeerID: PeerID(str: "0011223344556677"),
+                recipientPeerID: PeerID(str: "8899aabbccddeeff"),
+                fileName: "img_20260725_105708_1CC2760D-76AA-40C3-8013-C7FAA6C2EF99.jpg"
+            ),
+            "media-910bd42c65060ab76bb6406f220c4516"
+        )
+    }
 }

bitchatTests/Services/BLEFileTransferHandlerTests.swift

@@ -13,11 +13,20 @@ struct BLEFileTransferHandlerTests {
 
         var signatureVerifyCount = 0
         var signedNameQueries: [PeerID] = []
+        var blockedPeers: Set<PeerID> = []
         var trackedPackets: [BitchatPacket] = []
         var quotaReservations: [Int] = []
         var saveCalls: [(data: Data, preferredName: String?, subdirectory: String, fallbackExtension: String?, defaultPrefix: String)] = []
         var lastSeenUpdates: [PeerID] = []
+        var duplicateDeliveryAcks: [(messageID: String, peerID: PeerID)] = []
         var deliveredMessages: [BitchatMessage] = []
+        var saveOverride: ((
+            _ data: Data,
+            _ preferredName: String?,
+            _ subdirectory: String,
+            _ fallbackExtension: String?,
+            _ defaultPrefix: String
+        ) -> URL?)?
     }
 
     private let localPeerID = PeerID(str: "0102030405060708")
@@ -46,11 +55,20 @@ struct BLEFileTransferHandlerTests {
             },
             saveIncomingFile: { data, preferredName, subdirectory, fallbackExtension, defaultPrefix in
                 recorder.saveCalls.append((data, preferredName, subdirectory, fallbackExtension, defaultPrefix))
+                if let saveOverride = recorder.saveOverride {
+                    return saveOverride(data, preferredName, subdirectory, fallbackExtension, defaultPrefix)
+                }
                 return recorder.saveResult
             },
+            isPrivateMediaSenderBlocked: { peerID in
+                recorder.blockedPeers.contains(peerID)
+            },
             updatePeerLastSeen: { peerID in
                 recorder.lastSeenUpdates.append(peerID)
             },
+            acknowledgePrivateMediaDuplicate: { messageID, peerID in
+                recorder.duplicateDeliveryAcks.append((messageID, peerID))
+            },
             deliverMessage: { message in
                 recorder.deliveredMessages.append(message)
             }
@@ -284,6 +302,7 @@ struct BLEFileTransferHandlerTests {
         #expect(recorder.lastSeenUpdates == [remotePeerID])
         #expect(recorder.deliveredMessages.count == 1)
         #expect(recorder.deliveredMessages.first?.isPrivate == true)
+        #expect(recorder.deliveredMessages.first?.id.hasPrefix("media-") == false)
         // Must be explicit: BitchatMessage defaults private messages to
         // .sending, which the media views render as an in-flight send
         // (empty reveal mask, disabled reveal tap).
@@ -296,8 +315,9 @@ struct BLEFileTransferHandlerTests {
         recorder.peers = [remotePeerID: makePeerInfo(remotePeerID, nickname: "Alice", isVerified: true)]
         let handler = makeHandler(recorder: recorder)
         let content = Data([0xFF, 0xD8, 0xFF]) + Data(repeating: 0x41, count: 128)
+        let fileName = "img_20260725_105708_1CC2760D-76AA-40C3-8013-C7FAA6C2EF99.jpg"
         let file = BitchatFilePacket(
-            fileName: "secret.jpg",
+            fileName: fileName,
             fileSize: UInt64(content.count),
             mimeType: "image/jpeg",
             content: content
@@ -316,6 +336,173 @@ struct BLEFileTransferHandlerTests {
         #expect(recorder.deliveredMessages.count == 1)
         #expect(recorder.deliveredMessages.first?.isPrivate == true)
         #expect(recorder.deliveredMessages.first?.timestamp == timestamp)
+        #expect(recorder.deliveredMessages.first?.id == PrivateMediaMessageIdentity.stableID(
+            senderPeerID: remotePeerID,
+            recipientPeerID: localPeerID,
+            fileName: fileName
+        ))
+    }
+
+    @Test
+    func repeatedLegacyPrivateImageNamesKeepDistinctRandomMessageIDs() throws {
+        let recorder = Recorder()
+        recorder.peers = [remotePeerID: makePeerInfo(remotePeerID, nickname: "Alice", isVerified: true)]
+        let handler = makeHandler(recorder: recorder)
+        let content = Data([0xFF, 0xD8, 0xFF]) + Data(repeating: 0x41, count: 128)
+        let file = BitchatFilePacket(
+            fileName: "photo.jpg",
+            fileSize: UInt64(content.count),
+            mimeType: "image/jpeg",
+            content: content
+        )
+        let payload = try #require(file.encode())
+
+        #expect(handler.handlePrivatePayload(
+            payload,
+            from: remotePeerID,
+            timestamp: Date(timeIntervalSince1970: 1_234)
+        ))
+        #expect(handler.handlePrivatePayload(
+            payload,
+            from: remotePeerID,
+            timestamp: Date(timeIntervalSince1970: 1_235)
+        ))
+
+        #expect(recorder.deliveredMessages.count == 2)
+        #expect(recorder.deliveredMessages[0].id != recorder.deliveredMessages[1].id)
+        #expect(recorder.deliveredMessages.allSatisfy { !$0.id.hasPrefix("media-") })
+    }
+
+    @Test
+    func repeatedStablePrivateMediaIsAcknowledgedWithoutQuotaOrDiskWork() throws {
+        let recorder = Recorder()
+        recorder.peers = [remotePeerID: makePeerInfo(remotePeerID, nickname: "Alice", isVerified: true)]
+        let handler = makeHandler(recorder: recorder)
+        let content = Data([0xFF, 0xD8, 0xFF]) + Data(repeating: 0x41, count: 128)
+        let fileName = "img_20260725_105708_1CC2760D-76AA-40C3-8013-C7FAA6C2EF99.jpg"
+        let file = BitchatFilePacket(
+            fileName: fileName,
+            fileSize: UInt64(content.count),
+            mimeType: "image/jpeg",
+            content: content
+        )
+        let payload = try #require(file.encode())
+        let expectedID = try #require(PrivateMediaMessageIdentity.stableID(
+            senderPeerID: remotePeerID,
+            recipientPeerID: localPeerID,
+            fileName: fileName
+        ))
+
+        #expect(handler.handlePrivatePayload(
+            payload,
+            from: remotePeerID,
+            timestamp: Date(timeIntervalSince1970: 1_234)
+        ))
+        #expect(handler.handlePrivatePayload(
+            payload,
+            from: remotePeerID,
+            timestamp: Date(timeIntervalSince1970: 1_235)
+        ))
+
+        #expect(recorder.quotaReservations == [content.count])
+        #expect(recorder.saveCalls.count == 1)
+        #expect(recorder.deliveredMessages.count == 1)
+        #expect(recorder.lastSeenUpdates == [remotePeerID, remotePeerID])
+        #expect(recorder.duplicateDeliveryAcks.count == 1)
+        #expect(recorder.duplicateDeliveryAcks.first?.messageID == expectedID)
+        #expect(recorder.duplicateDeliveryAcks.first?.peerID == remotePeerID)
+    }
+
+    @Test
+    func inFlightStableDuplicateIsNotAcknowledgedAndFailedSaveRemainsRetryable() throws {
+        let recorder = Recorder()
+        recorder.peers = [remotePeerID: makePeerInfo(remotePeerID, nickname: "Alice", isVerified: true)]
+        let content = Data([0xFF, 0xD8, 0xFF]) + Data(repeating: 0x41, count: 128)
+        let file = BitchatFilePacket(
+            fileName: "img_20260725_105708_1CC2760D-76AA-40C3-8013-C7FAA6C2EF99.jpg",
+            fileSize: UInt64(content.count),
+            mimeType: "image/jpeg",
+            content: content
+        )
+        let payload = try #require(file.encode())
+        var handler: BLEFileTransferHandler!
+        var nestedResult: Bool?
+        var failFirstSave = true
+        recorder.saveOverride = { _, _, _, _, _ in
+            if failFirstSave {
+                failFirstSave = false
+                nestedResult = handler.handlePrivatePayload(
+                    payload,
+                    from: self.remotePeerID,
+                    timestamp: Date(timeIntervalSince1970: 1_235)
+                )
+                return nil
+            }
+            return recorder.saveResult
+        }
+        handler = makeHandler(recorder: recorder)
+
+        // The nested arrival sees the first reservation as pending. It is
+        // coalesced without an ACK; then the first durable save fails.
+        #expect(!handler.handlePrivatePayload(
+            payload,
+            from: remotePeerID,
+            timestamp: Date(timeIntervalSince1970: 1_234)
+        ))
+        #expect(nestedResult == true)
+        #expect(recorder.saveCalls.count == 1)
+        #expect(recorder.duplicateDeliveryAcks.isEmpty)
+        #expect(recorder.deliveredMessages.isEmpty)
+
+        // Failure released the reservation, so the sender's later retry can
+        // persist and deliver normally.
+        #expect(handler.handlePrivatePayload(
+            payload,
+            from: remotePeerID,
+            timestamp: Date(timeIntervalSince1970: 1_236)
+        ))
+        #expect(recorder.saveCalls.count == 2)
+        #expect(recorder.duplicateDeliveryAcks.isEmpty)
+        #expect(recorder.deliveredMessages.count == 1)
+    }
+
+    @Test
+    func blockedPrivateMediaIsDroppedBeforeQuotaDiskAndDedupState() throws {
+        let recorder = Recorder()
+        recorder.blockedPeers = [remotePeerID]
+        recorder.peers = [remotePeerID: makePeerInfo(remotePeerID, nickname: "Alice", isVerified: true)]
+        let handler = makeHandler(recorder: recorder)
+        let content = Data([0xFF, 0xD8, 0xFF]) + Data(repeating: 0x41, count: 128)
+        let file = BitchatFilePacket(
+            fileName: "img_20260725_105708_1CC2760D-76AA-40C3-8013-C7FAA6C2EF99.jpg",
+            fileSize: UInt64(content.count),
+            mimeType: "image/jpeg",
+            content: content
+        )
+        let payload = try #require(file.encode())
+
+        #expect(handler.handlePrivatePayload(
+            payload,
+            from: remotePeerID,
+            timestamp: Date(timeIntervalSince1970: 1_234)
+        ))
+
+        #expect(recorder.quotaReservations.isEmpty)
+        #expect(recorder.saveCalls.isEmpty)
+        #expect(recorder.lastSeenUpdates.isEmpty)
+        #expect(recorder.duplicateDeliveryAcks.isEmpty)
+        #expect(recorder.deliveredMessages.isEmpty)
+
+        // Unblocking must allow a retry through; the blocked attempt cannot
+        // poison the stable-ID dedup reservation.
+        recorder.blockedPeers = []
+        #expect(handler.handlePrivatePayload(
+            payload,
+            from: remotePeerID,
+            timestamp: Date(timeIntervalSince1970: 1_235)
+        ))
+        #expect(recorder.saveCalls.count == 1)
+        #expect(recorder.deliveredMessages.count == 1)
     }
 
     @Test
@@ -337,6 +524,7 @@ struct BLEFileTransferHandlerTests {
         #expect(recorder.quotaReservations.isEmpty)
         #expect(recorder.saveCalls.isEmpty)
         #expect(recorder.lastSeenUpdates.isEmpty)
+        #expect(recorder.duplicateDeliveryAcks.isEmpty)
         #expect(recorder.deliveredMessages.isEmpty)
     }