fix: resolve multiple critical bugs identified in code review

- fix(engine): resolve aria2 port TOCTOU race and secure conf file

- fix(server): eliminate main queue deadlock risk in local extension server

- fix(controller): ensure synchronous state save on app termination

- fix(ui): fix table skipping new items by diffing identity instead of count

- fix(scheduler): use 2-letter abbreviations to resolve day name collisions

- fix(settings): purge keychain orphans when primer access is denied

- fix(metadata): prevent synchronous DNS resolution from blocking async pool

- refactor: clean up dead code and unused variables

Sources/Firelink/AddDownloadsView.swift

@@ -322,7 +322,7 @@ struct AddDownloadsView: View {
                         ProgressView().controlSize(.small)
                         Text("Fetching media options...")
                             .foregroundStyle(.secondary)
-                    } else if case .failed(let error) = firstMedia.state {
+                    } else if case .failed(_) = firstMedia.state {
                         Image(systemName: "exclamationmark.triangle.fill").foregroundStyle(.red)
                         Text("Failed to load options.")
                             .foregroundStyle(.secondary)

Sources/Firelink/AppSettings.swift

@@ -445,7 +445,7 @@ final class AppSettings: ObservableObject {
                 extensionPairingToken = Self.generateSecureToken()
             }
         } else {
-            isKeychainAccessGranted = false
+            revokeKeychainAccess()
         }
     }
 

Sources/Firelink/Aria2DownloadEngine.swift

@@ -2,7 +2,7 @@ import Foundation
 import CFNetwork
 import Network
 
-final class Aria2DownloadEngine {
+final class Aria2DownloadEngine: Sendable {
     struct Handle {
         let processIdentifier: Int32
         let rpcPort: Int
@@ -107,7 +107,7 @@ final class Aria2DownloadEngine {
         speedLimitKiBPerSecond: Int?,
         progress: @escaping @Sendable (DownloadProgress) -> Void,
         completion: @escaping @Sendable (Result<Void, Error>) -> Void
-    ) throws -> Handle {
+    ) async throws -> Handle {
         guard let executableURL else {
             throw EngineError.executableNotFound
         }
@@ -117,19 +117,33 @@ final class Aria2DownloadEngine {
             withIntermediateDirectories: true
         )
 
+        var lastError: Error?
+
+        for _ in 1...5 {
             let rpcPort = Self.findFreePort()
             let rpcSecret = UUID().uuidString
-        let confURL = URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent("firelink-aria2-\(UUID().uuidString).conf")
+            let tempDir = URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent("firelink-aria2-\(UUID().uuidString)")
+            
+            do {
+                try FileManager.default.createDirectory(at: tempDir, withIntermediateDirectories: true, attributes: [.posixPermissions: 0o700])
+            } catch {
+                lastError = EngineError.launchFailed("Could not create secure temporary directory: \(error.localizedDescription)")
+                continue
+            }
+            
+            let confURL = tempDir.appendingPathComponent("aria2.conf")
             do {
                 let confContent = "rpc-secret=\(rpcSecret)\n"
                 try confContent.write(to: confURL, atomically: true, encoding: .utf8)
-            try FileManager.default.setAttributes([.posixPermissions: 0o600], ofItemAtPath: confURL.path)
             } catch {
-            throw EngineError.launchFailed("Could not write secure configuration file: \(error.localizedDescription)")
+                lastError = EngineError.launchFailed("Could not write secure configuration file: \(error.localizedDescription)")
+                continue
             }
 
             let process = Process()
             process.executableURL = executableURL
+            
+            do {
                 process.arguments = try arguments(
                     for: item,
                     proxyConfiguration: proxyConfiguration,
@@ -137,6 +151,10 @@ final class Aria2DownloadEngine {
                     rpcPort: rpcPort,
                     confURL: confURL
                 )
+            } catch {
+                lastError = error
+                break
+            }
 
             let inputPipe = Pipe()
             let outputPipe = Pipe()
@@ -169,7 +187,7 @@ final class Aria2DownloadEngine {
         }
 
         process.terminationHandler = { finishedProcess in
-            try? FileManager.default.removeItem(at: confURL)
+            try? FileManager.default.removeItem(at: tempDir)
             completionMonitor.cancel()
             outputPipe.fileHandleForReading.readabilityHandler = nil
             errorPipe.fileHandleForReading.readabilityHandler = nil
@@ -190,6 +208,7 @@ final class Aria2DownloadEngine {
             completionGate.complete(.failure(EngineError.launchFailed(message.isEmpty ? "exit code \(finishedProcess.terminationStatus)" : message)))
         }
 
+            var didThrow = false
             do {
                 try process.run()
                 if let input = inputFileContent(for: item).data(using: .utf8) {
@@ -197,8 +216,25 @@ final class Aria2DownloadEngine {
                 }
                 inputPipe.fileHandleForWriting.closeFile()
             } catch {
-            try? FileManager.default.removeItem(at: confURL)
+                didThrow = true
-            throw EngineError.launchFailed(error.localizedDescription)
+                lastError = EngineError.launchFailed(error.localizedDescription)
+            }
+            
+            if didThrow {
+                try? FileManager.default.removeItem(at: tempDir)
+                continue
+            }
+            
+            try? await Task.sleep(nanoseconds: 100_000_000)
+            
+            if !process.isRunning {
+                let stderr = String(data: errorBuffer.data, encoding: .utf8) ?? ""
+                if stderr.contains("Address already in use") || stderr.contains("Failed to bind") || stderr.contains("bind: Address") {
+                    try? FileManager.default.removeItem(at: tempDir)
+                    continue
+                }
+                // If it exited for another reason, we might still want to fail or let the terminationHandler process it.
+                // But the terminationHandler will hit completionGate, so we just return the handle.
             }
 
             completionMonitor.set(
@@ -215,10 +251,13 @@ final class Aria2DownloadEngine {
                 if process.isRunning {
                     process.terminate()
                 }
-            try? FileManager.default.removeItem(at: confURL)
+                try? FileManager.default.removeItem(at: tempDir)
             }
         }
         
+        throw lastError ?? EngineError.launchFailed("Failed to start aria2c after 5 attempts.")
+    }
+
     private static func monitorCompletion(
         rpcPort: Int,
         rpcSecret: String,

Sources/Firelink/DownloadController.swift

@@ -74,7 +74,7 @@ final class DownloadController: ObservableObject {
 
         NotificationCenter.default.publisher(for: NSApplication.willTerminateNotification)
             .sink { [weak self] _ in
-                self?.saveDownloads()
+                self?.saveDownloadsSync()
             }
             .store(in: &cancellables)
 
@@ -371,12 +371,7 @@ final class DownloadController: ObservableObject {
         pumpQueue()
     }
 
-    func remove(at offsets: IndexSet, deleteFiles: Bool = false) {
+
-        for index in offsets {
-            let item = downloads[index]
-            delete(item, deleteFiles: deleteFiles)
-        }
-    }
 
     func delete(_ item: DownloadItem, deleteFiles: Bool = false) {
         activeHandles[item.id]?.cancel()
@@ -598,11 +593,13 @@ final class DownloadController: ObservableObject {
                 }
             }
         } else {
+            Task {
                 do {
-                let handle = try engine.start(
+                    let liveItem = injectedEngineItem(from: item)
-                    item: injectedEngineItem(from: item),
+                    let handle = try await engine.start(
+                        item: liveItem,
                         proxyConfiguration: settings.downloadProxyConfiguration,
-                    speedLimitKiBPerSecond: effectiveSpeedLimitKiBPerSecond(for: item),
+                        speedLimitKiBPerSecond: effectiveSpeedLimitKiBPerSecond(for: liveItem),
                         progress: { [weak self] progress in
                             Task { @MainActor in
                                 let now = Date()
@@ -627,6 +624,12 @@ final class DownloadController: ObservableObject {
                             }
                         }
                     )
+                    
+                    await MainActor.run {
+                        guard activeDownloadItem(id: item.id) != nil else {
+                            handle.cancel()
+                            return
+                        }
                         activeHandles[item.id] = handle
                         update(item.id) {
                             $0.rpcPort = handle.rpcPort
@@ -636,7 +639,9 @@ final class DownloadController: ObservableObject {
                         saveDownloads()
                         applySpeedLimitsToActiveDownloads()
                         updateSleepActivity()
+                    }
                 } catch {
+                    await MainActor.run {
                         handleDownloadFailure(itemID: item.id, error: error)
                         applySpeedLimitsToActiveDownloads()
                         updateSleepActivity()
@@ -644,6 +649,8 @@ final class DownloadController: ObservableObject {
                     }
                 }
             }
+        }
+    }
 
     private func activeDownloadItem(id: UUID) -> DownloadItem? {
         downloads.first { $0.id == id && $0.status == .downloading }
@@ -996,6 +1003,22 @@ final class DownloadController: ObservableObject {
         }
     }
 
+    private func saveDownloadsSync() {
+        let queuesCopy = queues
+        let downloadsCopy = downloads.map(\.redactedForPersistence)
+        let storageURL = self.storageURL
+
+        do {
+            let directory = storageURL.deletingLastPathComponent()
+            try FileManager.default.createDirectory(at: directory, withIntermediateDirectories: true, attributes: nil)
+            let state = StoredDownloadState(queues: queuesCopy, downloads: downloadsCopy)
+            let data = try JSONEncoder().encode(state)
+            try data.write(to: storageURL, options: .atomic)
+        } catch {
+            print("Failed to synchronously save downloads: \(error)")
+        }
+    }
+
     private func saveDownloads() {
         let queuesCopy = queues
         let downloadsCopy = downloads.map(\.redactedForPersistence)

Sources/Firelink/DownloadMetadataFetcher.swift

@@ -54,10 +54,15 @@ enum DownloadMetadataFetcher {
             return pending
         }
 
-        if isAutoFetch, let host = url.host, isPrivateHost(host) {
+        if isAutoFetch, let host = url.host {
+            let isPrivate = await Task.detached {
+                isPrivateHost(host)
+            }.value
+            if isPrivate {
                 pending.state = .loaded
                 return pending
             }
+        }
 
         var request = URLRequest(url: url)
         request.httpMethod = "HEAD"

Sources/Firelink/DownloadTable.swift

@@ -126,7 +126,9 @@ struct DownloadTable: View {
         }
         .onAppear { sortedItems = items.sorted(using: sortOrder) }
         .onChange(of: items) { _, newItems in
-            if newItems.count != sortedItems.count {
+            let existingIDs = Set(sortedItems.map(\.id))
+            let newIDs = Set(newItems.map(\.id))
+            if existingIDs != newIDs {
                 sortedItems = newItems.sorted(using: sortOrder)
             } else {
                 let itemsDict = Dictionary(uniqueKeysWithValues: newItems.map { ($0.id, $0) })

Sources/Firelink/LocalExtensionServer.swift

@@ -1,6 +1,7 @@
 import Foundation
 import Network
 import AppKit
+import Combine
 
 final class LocalExtensionServer: @unchecked Sendable {
     private enum Constants {
@@ -17,6 +18,11 @@ final class LocalExtensionServer: @unchecked Sendable {
     private let queue = DispatchQueue(label: "local.firelink.server")
     let port: UInt16
     
+    private let tokenLock = NSLock()
+    private var _pairingToken: String = ""
+    private var cancellables = Set<AnyCancellable>()
+
+    @MainActor
     init?(downloadController: DownloadController, settings: AppSettings) {
         self.downloadController = downloadController
         self.settings = settings
@@ -42,6 +48,16 @@ final class LocalExtensionServer: @unchecked Sendable {
 
         self.listener = createdListener
         self.port = selectedPort ?? 6412
+
+        settings.$extensionPairingToken
+            .sink { [weak self] token in
+                self?.tokenLock.withLock { self?._pairingToken = token }
+            }
+            .store(in: &cancellables)
+    }
+
+    private var currentPairingToken: String {
+        tokenLock.withLock { _pairingToken }
     }
 
     func start() {
@@ -139,7 +155,7 @@ final class LocalExtensionServer: @unchecked Sendable {
             return isAllowedExtensionOrigin(request.header(named: "origin") ?? "") ? .noContent : .forbidden
         }
 
-        let expectedToken = DispatchQueue.main.sync { settings.extensionPairingToken }
+        let expectedToken = currentPairingToken
         guard let token = request.header(named: Constants.extensionRequestHeader),
               token == expectedToken else {
             return .forbidden

Sources/Firelink/SchedulerController.swift

@@ -18,13 +18,13 @@ enum SchedulerDay: Int, Codable, CaseIterable, Identifiable {
 
     var shortName: String {
         switch self {
-        case .sunday: "S"
+        case .sunday: "Su"
-        case .monday: "M"
+        case .monday: "Mo"
-        case .tuesday: "T"
+        case .tuesday: "Tu"
-        case .wednesday: "W"
+        case .wednesday: "We"
-        case .thursday: "T"
+        case .thursday: "Th"
-        case .friday: "F"
+        case .friday: "Fr"
-        case .saturday: "S"
+        case .saturday: "Sa"
         }
     }
 }