Persist private media delivery receipts

bitchatTests/ChatMediaTransferCoordinatorContextTests.swift

@@ -8,7 +8,7 @@
 // `ChatPrivateConversationCoordinatorContextTests` exemplars.
 //
 // Real file/codec work remains covered by `ChatMediaPreparationTests`. These
-// tests inject a paused voice-note preparer to exercise cancellation ownership
+// tests inject paused media preparers to exercise cancellation ownership
 // across the detached-preparation/MainActor boundary deterministically.
 //
 
@@ -216,6 +216,65 @@ private final class PausedVoiceNotePreparer: @unchecked Sendable {
     }
 }
 
+private final class PausedImagePreparer: @unchecked Sendable {
+    private let condition = NSCondition()
+    private var started = false
+    private var released = false
+    private var finished = false
+    let outputURL: URL
+
+    init(outputURL: URL) {
+        self.outputURL = outputURL
+    }
+
+    func prepare(_ sourceURL: URL) throws -> ChatPreparedImage {
+        condition.lock()
+        started = true
+        condition.broadcast()
+        while !released {
+            condition.wait()
+        }
+        condition.unlock()
+
+        let content = Data([0xFF, 0xD8, 0xFF, 0xD9])
+        try content.write(to: outputURL, options: .atomic)
+        let prepared = ChatPreparedImage(
+            outputURL: outputURL,
+            packet: BitchatFilePacket(
+                fileName: outputURL.lastPathComponent,
+                fileSize: UInt64(content.count),
+                mimeType: "image/jpeg",
+                content: content
+            )
+        )
+
+        condition.lock()
+        finished = true
+        condition.broadcast()
+        condition.unlock()
+        return prepared
+    }
+
+    var hasStarted: Bool {
+        condition.lock()
+        defer { condition.unlock() }
+        return started
+    }
+
+    var hasFinished: Bool {
+        condition.lock()
+        defer { condition.unlock() }
+        return finished
+    }
+
+    func release() {
+        condition.lock()
+        released = true
+        condition.broadcast()
+        condition.unlock()
+    }
+}
+
 // MARK: - Coordinator Tests Against Mock Context
 
 /// Exercises `ChatMediaTransferCoordinator` against
@@ -409,6 +468,54 @@ struct ChatMediaTransferCoordinatorContextTests {
         coordinator.cleanupLocalFile(forMessage: message)
     }
 
+    @Test @MainActor
+    func panicDuringImagePreparationDeletesStaleOutputWithoutSideEffects() async throws {
+        let context = MockChatMediaTransferContext()
+        let peerID = PeerID(str: "99aabbccddeeff00")
+        context.selectedPrivateChatPeer = peerID
+        let sourceURL = try makeCoordinatorTestImageURL()
+        let outputURL = FileManager.default.temporaryDirectory
+            .appendingPathComponent(
+                "panic-stale-image-\(UUID().uuidString).jpg"
+            )
+        let preparer = PausedImagePreparer(outputURL: outputURL)
+        let coordinator = ChatMediaTransferCoordinator(
+            context: context,
+            prepareImagePacket: { url in try preparer.prepare(url) }
+        )
+        defer {
+            preparer.release()
+            try? FileManager.default.removeItem(at: sourceURL)
+            try? FileManager.default.removeItem(at: outputURL)
+        }
+
+        coordinator.sendImage(from: sourceURL)
+        #expect(await TestHelpers.waitUntil(
+            { preparer.hasStarted },
+            timeout: TestConstants.longTimeout
+        ))
+
+        coordinator.resetForPanic()
+        preparer.release()
+
+        #expect(await TestHelpers.waitUntil(
+            { preparer.hasFinished },
+            timeout: TestConstants.longTimeout
+        ))
+        #expect(await TestHelpers.waitUntil(
+            { !FileManager.default.fileExists(atPath: outputURL.path) },
+            timeout: TestConstants.longTimeout
+        ))
+        #expect(context.privateChats[peerID]?.isEmpty != false)
+        #expect(context.appendedPublicMessages.isEmpty)
+        #expect(context.privateFileSends.isEmpty)
+        #expect(context.broadcastFileSends.isEmpty)
+        #expect(context.systemMessages.isEmpty)
+        #expect(context.deliveryStatusUpdates.isEmpty)
+        #expect(coordinator.transferIdToMessageIDs.isEmpty)
+        #expect(coordinator.messageIDToTransferId.isEmpty)
+    }
+
     @Test @MainActor
     func cancelVoiceNoteDuringDetachedPreparationCannotSendOrRestoreMapping() async throws {
         let context = MockChatMediaTransferContext()