project setup

App/PadXcodeDaemonApp.swift

@@ -1,27 +1,50 @@
 import SwiftUI
+import AppKit
+
+// MARK: - App Delegate
+
+final class PadXcodeDaemonDelegate: NSObject, NSApplicationDelegate {
+
+    func applicationDidFinishLaunching(_ notification: Notification) {
+        // Start daemon on app launch. The controller is created by the App
+        // struct before this fires and stored in the shared reference below.
+        guard let controller = PadXcodeDaemonApp.sharedController else { return }
+        Task { @MainActor in
+            await controller.start()
+        }
+    }
+
+    func applicationShouldTerminateAfterLastWindowClosed(_ sender: NSApplication) -> Bool {
+        return false
+    }
+}
+
+// MARK: - App
 
 @main
 struct PadXcodeDaemonApp: App {
 
-    @StateObject private var preferences  = AppPreferences()
-    @State       private var controller:    DaemonController
+    @NSApplicationDelegateAdaptor(PadXcodeDaemonDelegate.self) private var appDelegate
+    @StateObject private var preferences = AppPreferences()
+    @StateObject private var controller: DaemonController
+
+    // Static reference so the delegate can access the controller before
+    // SwiftUI finishes wiring up @State bindings.
+    static var sharedController: DaemonController?
 
     init() {
         ensureConfigFile()
         let prefs = AppPreferences()
-        _preferences  = StateObject(wrappedValue: prefs)
-        _controller   = State(wrappedValue: DaemonController(preferences: prefs))
+        let ctrl  = DaemonController(preferences: prefs)
+        _preferences = StateObject(wrappedValue: prefs)
+        _controller  = StateObject(wrappedValue: ctrl)
+        // Store before applicationDidFinishLaunching fires.
+        PadXcodeDaemonApp.sharedController = ctrl
     }
 
     var body: some Scene {
         MenuBarExtra {
             MenuBarView(controller: controller, preferences: preferences)
-                .task {
-                    // Start daemon on first appearance if not already running
-                    if !controller.serverState.isRunning {
-                        await controller.start()
-                    }
-                }
         } label: {
             MenuBarIcon(controller: controller)
         }

Daemon/BuildManager.swift

@@ -14,11 +14,20 @@ final class BuildSession: @unchecked Sendable {
     private let logger: Logger
     private var clients: [WebSocket] = []
     private let lock = NSLock()
+    private var activeProcess: Process?
 
     init(id: String, logger: Logger) { self.id = id; self.logger = logger }
 
     func addClient(_ ws: WebSocket) { lock.lock(); defer { lock.unlock() }; clients.append(ws) }
 
+    /// Terminate the active xcodebuild process. Called when iPad disconnects mid-build.
+    func cancelBuild() {
+        lock.lock(); let p = activeProcess; lock.unlock()
+        p?.terminate()
+        broadcast(BuildLogMessage(type: .status,
+            text: "⚠️ Build cancelled by client disconnect.", exitCode: -2))
+    }
+
     func broadcast(_ message: BuildLogMessage) {
         guard let data = try? JSONEncoder().encode(message),
               let text = String(data: data, encoding: .utf8) else { return }
@@ -34,6 +43,21 @@ final class BuildSession: @unchecked Sendable {
             process.arguments = arguments
             let outPipe = Pipe(); let errPipe = Pipe()
             process.standardOutput = outPipe; process.standardError = errPipe
+
+            // Guard against double-resume: if process.run() throws, the pipe handlers
+            // still fire with empty data → group.notify would call resume a second time.
+            final class ResumeOnce {
+                private let lock = NSLock()
+                private var done = false
+                func resume(continuation: CheckedContinuation<Int32, Never>, returning value: Int32) {
+                    lock.lock(); defer { lock.unlock() }
+                    guard !done else { return }
+                    done = true
+                    continuation.resume(returning: value)
+                }
+            }
+            let guard_ = ResumeOnce()
+
             let group = DispatchGroup()
             group.enter()
             outPipe.fileHandleForReading.readabilityHandler = { [weak self] h in
@@ -50,15 +74,19 @@ final class BuildSession: @unchecked Sendable {
             process.terminationHandler = { [weak self] proc in
                 let code = proc.terminationStatus
                 group.notify(queue: .global()) {
+                    self?.lock.lock(); self?.activeProcess = nil; self?.lock.unlock()
                     let msg = code == 0 ? "✅ Build succeeded." : "❌ Build failed (exit \(code))."
                     self?.broadcast(BuildLogMessage(type: .status, text: msg, exitCode: Int(code)))
-                    continuation.resume(returning: code)
+                    guard_.resume(continuation: continuation, returning: code)
                 }
             }
-            do { try process.run(); logger.info("xcodebuild started. PID: \(process.processIdentifier)") }
-            catch {
+            do {
+                try process.run()
+                lock.lock(); activeProcess = process; lock.unlock()
+                logger.info("xcodebuild started. PID: \(process.processIdentifier)")
+            } catch {
                 broadcast(BuildLogMessage(type: .stderr, text: "Failed to launch xcodebuild: \(error)", exitCode: nil))
-                continuation.resume(returning: -1)
+                guard_.resume(continuation: continuation, returning: -1)
             }
         }
     }

Daemon/DaemonController.swift

@@ -1,6 +1,5 @@
 import Foundation
 import Vapor
-import Observation
 
 enum ServerState: Equatable {
     case stopped
@@ -41,18 +40,16 @@ struct DaemonLogLine: Identifiable {
             }
         }
     }
-    var formattedTime: String {
-        let f = DateFormatter(); f.dateFormat = "HH:mm:ss"; return f.string(from: date)
-    }
+    var formattedTime: String { DaemonLogLine.timeFormatter.string(from: date) }
+    private static let timeFormatter: DateFormatter = { let f = DateFormatter(); f.dateFormat = "HH:mm:ss"; return f }()
 }
 
-@Observable
 @MainActor
-final class DaemonController {
-    var serverState: ServerState = .stopped
-    var connectedClients: [ConnectedClient] = []
-    var logLines: [DaemonLogLine] = []
-    var buildCount: Int = 0
+final class DaemonController: ObservableObject {
+    @Published var serverState: ServerState = .stopped
+    @Published var connectedClients: [ConnectedClient] = []
+    @Published var logLines: [DaemonLogLine] = []
+    @Published var buildCount: Int = 0
     var preferences: AppPreferences
     private var vaporApp: Application?
     private let maxLogLines = 500
@@ -66,6 +63,7 @@ final class DaemonController {
     func start() async {
         guard !serverState.isRunning else { return }
         serverState = .starting
+        buildCount   = 0
         appendLog("Starting PadXcode daemon on port \(preferences.port)…", level: .info)
         do {
             var env = try Environment.detect()
@@ -78,10 +76,27 @@ final class DaemonController {
             app.http.server.configuration.port     = preferences.port
             try configure(app, controller: self)
             try await app.startup()
-            vaporApp    = app
-            serverState = .running(port: preferences.port, startedAt: Date())
-            appendLog("✅ Daemon running on 0.0.0.0:\(preferences.port)", level: .success)
-            appendLog("📡 Tailscale IP: \(preferences.tailscaleIP)", level: .info)
+
+            // If stop() was called while we were awaiting startup, abort.
+            guard case .starting = serverState else {
+                try? await app.asyncShutdown()
+                return
+            }
+
+            vaporApp = app
+
+            // Verify the HTTP server is actually listening before declaring running.
+            // app.startup() returning does not guarantee the port is bound yet.
+            let port = preferences.port
+            let verified = await verifyListening(port: port)
+            if verified {
+                serverState = .running(port: port, startedAt: Date())
+                appendLog("✅ Daemon running on 0.0.0.0:\(port)", level: .success)
+                appendLog("📡 Tailscale IP: \(preferences.tailscaleIP)", level: .info)
+            } else {
+                serverState = .error("Server started but port \(port) did not respond")
+                appendLog("❌ Server did not respond on port \(port) after startup", level: .error)
+            }
         } catch {
             serverState = .error(error.localizedDescription)
             appendLog("❌ Failed to start: \(error.localizedDescription)", level: .error)
@@ -89,7 +104,12 @@ final class DaemonController {
     }
 
     func stop() async {
-        guard serverState.isRunning else { return }
+        // Also handle .starting: if stop() arrives while Vapor is starting up,
+        // mark as stopped so the app doesn't become orphaned.
+        switch serverState {
+        case .running, .starting: break
+        default: return
+        }
         appendLog("Stopping daemon…", level: .info)
         try? await vaporApp?.asyncShutdown()
         vaporApp = nil; serverState = .stopped; connectedClients = []
@@ -114,4 +134,22 @@ final class DaemonController {
     }
     func clearLog() { logLines = [] }
     func applyPortChange() async { if serverState.isRunning { await restart() } }
+
+    // MARK: - Private: verify server is actually listening on the port
+
+    private func verifyListening(port: Int) async -> Bool {
+        // Retry up to 10 times with 300ms spacing — gives Vapor 3s to bind the port.
+        for attempt in 1...10 {
+            guard let url = URL(string: "http://127.0.0.1:\(port)/health") else { return false }
+            var req = URLRequest(url: url)
+            req.timeoutInterval = 1
+            if let (_, resp) = try? await URLSession.shared.data(for: req),
+               (resp as? HTTPURLResponse)?.statusCode == 200 {
+                appendLog("🔎 Health check passed on attempt \(attempt)", level: .info)
+                return true
+            }
+            try? await Task.sleep(for: .milliseconds(300))
+        }
+        return false
+    }
 }

Daemon/DeviceManager.swift

@@ -4,17 +4,25 @@ import Vapor
 struct DeviceManager {
 
     static func listConnectedDevices(logger: Logger) async -> [ConnectedDevice] {
-        let tmp = FileManager.default.temporaryDirectory
-            .appendingPathComponent("padxcode-devices-\(UUID().uuidString).json")
-        defer { try? FileManager.default.removeItem(at: tmp) }
-        let p = Process()
-        p.executableURL = URL(fileURLWithPath: "/usr/bin/xcrun")
-        p.arguments = ["devicectl", "list", "devices", "--json-output", tmp.path]
-        p.standardError = Pipe()
-        try? p.run(); p.waitUntilExit()
-        guard p.terminationStatus == 0,
-              let data = try? Data(contentsOf: tmp) else { return [] }
-        return parseDevicectlJSON(data, logger: logger)
+        // Run synchronous Process on a background thread to avoid blocking the NIO event loop.
+        await withCheckedContinuation { cont in
+            DispatchQueue.global(qos: .userInitiated).async {
+                let tmp = FileManager.default.temporaryDirectory
+                    .appendingPathComponent("padxcode-devices-\(UUID().uuidString).json")
+                defer { try? FileManager.default.removeItem(at: tmp) }
+                let p = Process()
+                p.executableURL = URL(fileURLWithPath: "/usr/bin/xcrun")
+                p.arguments = ["devicectl", "list", "devices", "--json-output", tmp.path]
+                p.standardError = Pipe()
+                try? p.run(); p.waitUntilExit()
+                guard p.terminationStatus == 0,
+                      let data = try? Data(contentsOf: tmp) else {
+                    cont.resume(returning: [])
+                    return
+                }
+                cont.resume(returning: parseDevicectlJSON(data, logger: logger))
+            }
+        }
     }
 
     @discardableResult
@@ -26,22 +34,44 @@ struct DeviceManager {
         let out = Pipe(); let err = Pipe()
         p.standardOutput = out; p.standardError = err
         return await withCheckedContinuation { cont in
+            let g = DispatchGroup()
+            // Clear handlers on empty data to prevent pipe handle leak after process exits.
+            g.enter()
             out.fileHandleForReading.readabilityHandler = { h in
-                let d = h.availableData; guard !d.isEmpty, let t = String(data: d, encoding: .utf8) else { return }
-                session.broadcast(BuildLogMessage(type: .stdout, text: t, exitCode: nil))
+                let d = h.availableData
+                if d.isEmpty { out.fileHandleForReading.readabilityHandler = nil; g.leave(); return }
+                if let t = String(data: d, encoding: .utf8) {
+                    session.broadcast(BuildLogMessage(type: .stdout, text: t, exitCode: nil))
+                }
             }
+            g.enter()
             err.fileHandleForReading.readabilityHandler = { h in
-                let d = h.availableData; guard !d.isEmpty, let t = String(data: d, encoding: .utf8) else { return }
-                session.broadcast(BuildLogMessage(type: .stderr, text: t, exitCode: nil))
+                let d = h.availableData
+                if d.isEmpty { err.fileHandleForReading.readabilityHandler = nil; g.leave(); return }
+                if let t = String(data: d, encoding: .utf8) {
+                    session.broadcast(BuildLogMessage(type: .stderr, text: t, exitCode: nil))
+                }
             }
             p.terminationHandler = { proc in
                 let code = proc.terminationStatus
-                session.broadcast(BuildLogMessage(type: .status,
-                    text: code == 0 ? "✅ App installed." : "❌ Install failed (exit \(code)).",
-                    exitCode: Int(code)))
-                cont.resume(returning: code)
+                // Wait for both pipes to drain before resuming the continuation,
+                // otherwise install/launch output is truncated.
+                g.notify(queue: .global()) {
+                    session.broadcast(BuildLogMessage(type: .status,
+                        text: code == 0 ? "✅ App installed." : "❌ Install failed (exit \(code)).",
+                        exitCode: Int(code)))
+                    cont.resume(returning: code)
+                }
+            }
+            // If xcrun fails to launch, terminationHandler never fires → continuation hangs forever.
+            // Catch the error and resume immediately.
+            do {
+                try p.run()
+            } catch {
+                session.broadcast(BuildLogMessage(type: .stderr,
+                    text: "❌ Failed to launch xcrun install: \(error)", exitCode: nil))
+                cont.resume(returning: -1)
             }
-            try? p.run()
         }
     }
 
@@ -53,22 +83,39 @@ struct DeviceManager {
         let out = Pipe(); let err = Pipe()
         p.standardOutput = out; p.standardError = err
         await withCheckedContinuation { (cont: CheckedContinuation<Void, Never>) in
+            let g = DispatchGroup()
+            g.enter()
             out.fileHandleForReading.readabilityHandler = { h in
-                let d = h.availableData; guard !d.isEmpty, let t = String(data: d, encoding: .utf8) else { return }
-                session.broadcast(BuildLogMessage(type: .stdout, text: t, exitCode: nil))
+                let d = h.availableData
+                if d.isEmpty { out.fileHandleForReading.readabilityHandler = nil; g.leave(); return }
+                if let t = String(data: d, encoding: .utf8) {
+                    session.broadcast(BuildLogMessage(type: .stdout, text: t, exitCode: nil))
+                }
             }
+            g.enter()
             err.fileHandleForReading.readabilityHandler = { h in
-                let d = h.availableData; guard !d.isEmpty, let t = String(data: d, encoding: .utf8) else { return }
-                session.broadcast(BuildLogMessage(type: .stderr, text: t, exitCode: nil))
+                let d = h.availableData
+                if d.isEmpty { err.fileHandleForReading.readabilityHandler = nil; g.leave(); return }
+                if let t = String(data: d, encoding: .utf8) {
+                    session.broadcast(BuildLogMessage(type: .stderr, text: t, exitCode: nil))
+                }
             }
             p.terminationHandler = { proc in
                 let code = proc.terminationStatus
-                session.broadcast(BuildLogMessage(type: .status,
-                    text: code == 0 ? "✅ App launched." : "⚠️ Launch exit \(code).",
-                    exitCode: Int(code)))
+                g.notify(queue: .global()) {
+                    session.broadcast(BuildLogMessage(type: .status,
+                        text: code == 0 ? "✅ App launched." : "⚠️ Launch exit \(code).",
+                        exitCode: Int(code)))
+                    cont.resume()
+                }
+            }
+            do {
+                try p.run()
+            } catch {
+                session.broadcast(BuildLogMessage(type: .stderr,
+                    text: "❌ Failed to launch xcrun launch: \(error)", exitCode: nil))
                 cont.resume()
             }
-            try? p.run()
         }
     }
 

Daemon/LSPProxy.swift

@@ -7,11 +7,25 @@ actor LSPProxy {
     private var stdinPipe: Pipe?
     private var clients: [WebSocket] = []
 
-    func start(projectPath: String) throws {
-        guard process == nil else { return }
+    func start(projectPath: String) async throws {
+        // If already running for a DIFFERENT project, restart for the new one.
+        // Keeping the old process would give wrong completions/diagnostics.
+        if process != nil {
+            stop()
+        }
+        // Resolve sourcekit-lsp via xcrun so we respect the active xcode-select toolchain.
+        // Run on a background thread because waitUntilExit() blocks.
+        let lspPath = await withCheckedContinuation { cont in
+            DispatchQueue.global(qos: .userInitiated).async {
+                cont.resume(returning: Self.resolveLSPPathSync())
+            }
+        }
+        guard FileManager.default.fileExists(atPath: lspPath) else {
+            throw NSError(domain: "LSPProxy", code: 1,
+                          userInfo: [NSLocalizedDescriptionKey: "sourcekit-lsp not found at \(lspPath)"])
+        }
         let p = Process()
-        p.executableURL = URL(fileURLWithPath:
-            "/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/sourcekit-lsp")
+        p.executableURL = URL(fileURLWithPath: lspPath)
         p.currentDirectoryURL = URL(fileURLWithPath: projectPath)
         let inPipe = Pipe(); let outPipe = Pipe(); let errPipe = Pipe()
         p.standardInput = inPipe; p.standardOutput = outPipe; p.standardError = errPipe
@@ -24,8 +38,8 @@ actor LSPProxy {
         try p.run(); process = p
     }
 
-    func stop() { process?.terminate(); process = nil; stdinPipe = nil }
-    private func handleTermination() { process = nil; broadcastStatus("lsp_terminated") }
+    func stop() { process?.terminate(); process = nil; stdinPipe = nil; clients.removeAll() }
+    private func handleTermination() { process = nil; broadcastStatus("lsp_terminated"); clients.removeAll() }
 
     func addClient(_ ws: WebSocket)    { clients.append(ws) }
     func removeClient(_ ws: WebSocket) { clients.removeAll { $0 === ws } }
@@ -51,6 +65,26 @@ actor LSPProxy {
         for ws in clients where !ws.isClosed { let w = ws; let msg = #"{"padxcode_status":"\#(s)"}"#; Task { try? await w.send(msg) } }
     }
 
+    private static func resolveLSPPathSync() -> String {
+        // Try xcrun first — respects xcode-select.
+        let xcrun = Process()
+        xcrun.executableURL = URL(fileURLWithPath: "/usr/bin/xcrun")
+        xcrun.arguments = ["--find", "sourcekit-lsp"]
+        let pipe = Pipe()
+        xcrun.standardOutput = pipe; xcrun.standardError = Pipe()
+        if let _ = try? xcrun.run() {
+            xcrun.waitUntilExit()
+            if xcrun.terminationStatus == 0,
+               let path = String(data: pipe.fileHandleForReading.readDataToEndOfFile(), encoding: .utf8)?
+                   .trimmingCharacters(in: .whitespacesAndNewlines),
+               !path.isEmpty {
+                return path
+            }
+        }
+        // Fallback to known default location.
+        return "/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/sourcekit-lsp"
+    }
+
     private func extractJSONBodies(from data: Data) -> [Data] {
         var results: [Data] = []; var rem = data
         let sep = Data([0x0D,0x0A,0x0D,0x0A])

Daemon/PreBuildRunner.swift

@@ -27,34 +27,56 @@ final class PreBuildRunner {
             p.environment = env
             let out = Pipe(); let err = Pipe()
             p.standardOutput = out; p.standardError = err
+
+            // Guard against double-resume: if p.run() throws, the catch block resumes first,
+            // then empty-data pipe handlers fire → g.leave()×2 → g.notify → second resume.
+            final class ResumeOnce {
+                private let lock = NSLock(); private var done = false
+                func resume(continuation: CheckedContinuation<Bool, Never>, returning value: Bool) {
+                    lock.lock(); defer { lock.unlock() }
+                    guard !done else { return }; done = true
+                    continuation.resume(returning: value)
+                }
+            }
+            let guard_ = ResumeOnce()
+
             final class TimedOutBox { var value = false }
             let timedOutBox = TimedOutBox()
             let wd = DispatchWorkItem { timedOutBox.value = true; p.terminate()
-                session.broadcast(BuildLogMessage(type: .stderr, text: "⏱ Hook '\(hook.name)' timed out.", exitCode: nil))
+                session.broadcast(BuildLogMessage(type: .stderr,
+                    text: "⏱ Hook '\(hook.name)' timed out.", exitCode: nil))
             }
             DispatchQueue.global().asyncAfter(deadline: .now() + .seconds(hook.timeoutSeconds), execute: wd)
+
             let g = DispatchGroup()
             g.enter()
             out.fileHandleForReading.readabilityHandler = { h in
                 let d = h.availableData
                 if d.isEmpty { out.fileHandleForReading.readabilityHandler = nil; g.leave(); return }
-                if let t = String(data: d, encoding: .utf8) { session.broadcast(BuildLogMessage(type: .stdout, text: t, exitCode: nil)) }
+                if let t = String(data: d, encoding: .utf8) {
+                    session.broadcast(BuildLogMessage(type: .stdout, text: t, exitCode: nil))
+                }
             }
             g.enter()
             err.fileHandleForReading.readabilityHandler = { h in
                 let d = h.availableData
                 if d.isEmpty { err.fileHandleForReading.readabilityHandler = nil; g.leave(); return }
-                if let t = String(data: d, encoding: .utf8) { session.broadcast(BuildLogMessage(type: .stderr, text: t, exitCode: nil)) }
+                if let t = String(data: d, encoding: .utf8) {
+                    session.broadcast(BuildLogMessage(type: .stderr, text: t, exitCode: nil))
+                }
             }
             p.terminationHandler = { proc in
                 wd.cancel()
-                g.notify(queue: .global()) { cont.resume(returning: proc.terminationStatus == 0 && !timedOutBox.value) }
+                g.notify(queue: .global()) {
+                    guard_.resume(continuation: cont,
+                                  returning: proc.terminationStatus == 0 && !timedOutBox.value)
+                }
             }
-            do { try p.run() }
-            catch {
+            do { try p.run() } catch {
                 wd.cancel()
-                session.broadcast(BuildLogMessage(type: .stderr, text: "Launch failed: \(error)", exitCode: nil))
-                cont.resume(returning: false)
+                session.broadcast(BuildLogMessage(type: .stderr,
+                    text: "Launch failed: \(error)", exitCode: nil))
+                guard_.resume(continuation: cont, returning: false)
             }
         }
     }

Daemon/Setup.swift

@@ -24,9 +24,16 @@ func ensureConfigFile() {
 }
 
 func loadTeamID() -> String {
+    // Prefer UserDefaults (set by Settings UI) over config file.
+    // This ensures changes made in the Settings window take effect immediately.
+    let fromDefaults = UserDefaults.standard.string(forKey: "developmentTeam") ?? ""
+    if !fromDefaults.isEmpty && fromDefaults != "YOUR_10_CHAR_TEAM_ID" { return fromDefaults }
+
+    // Fall back to ~/.padxcode/config.json for initial setup.
     let file = "\(NSHomeDirectory())/.padxcode/config.json"
     guard let data = try? Data(contentsOf: URL(fileURLWithPath: file)),
           let json = try? JSONDecoder().decode([String: String].self, from: data),
-          let id   = json["developmentTeam"] else { return "" }
+          let id   = json["developmentTeam"],
+          !id.isEmpty, id != "YOUR_10_CHAR_TEAM_ID" else { return fromDefaults }
     return id
 }

Daemon/routes.swift

@@ -9,54 +9,120 @@ func routes(_ app: Application) throws {
 
     // MARK: - Files
 
-    app.get("files", "tree") { req -> FileNode in
+    app.get("files", "tree") { req async throws -> FileNode in
         guard let path = req.query[String.self, at: "path"] else { throw Abort(.badRequest) }
-        return try buildFileTree(at: path)
+        // Run file I/O on a background thread so we don't block the NIO event loop.
+        return try await withCheckedThrowingContinuation { cont in
+            DispatchQueue.global(qos: .userInitiated).async {
+                do { cont.resume(returning: try buildFileTree(at: path)) }
+                catch { cont.resume(throwing: error) }
+            }
+        }
     }
 
-    app.get("files", "content") { req -> FileContentResponse in
+    app.get("files", "content") { req async throws -> FileContentResponse in
         guard let path = req.query[String.self, at: "path"] else { throw Abort(.badRequest) }
-        guard let content = try? String(contentsOfFile: path, encoding: .utf8) else { throw Abort(.notFound) }
-        return FileContentResponse(path: path, content: content)
+        // Run file I/O on a background thread so we don't block the NIO event loop.
+        return try await withCheckedThrowingContinuation { cont in
+            DispatchQueue.global(qos: .userInitiated).async {
+                guard let content = try? String(contentsOfFile: path, encoding: .utf8) else {
+                    cont.resume(throwing: Abort(.notFound))
+                    return
+                }
+                cont.resume(returning: FileContentResponse(path: path, content: content))
+            }
+        }
     }
 
-    app.put("files", "save") { req -> HTTPStatus in
+    app.put("files", "save") { req async throws -> HTTPStatus in
         let body = try req.content.decode(FileSaveRequest.self)
         guard !body.path.contains("..") else { throw Abort(.forbidden) }
-        let url = URL(fileURLWithPath: body.path)
-        try FileManager.default.createDirectory(
-            at: url.deletingLastPathComponent(), withIntermediateDirectories: true)
-        let tmp = url.deletingLastPathComponent()
-            .appendingPathComponent(".\(url.lastPathComponent).tmp")
-        try body.content.write(to: tmp, atomically: false, encoding: .utf8)
-        _ = try FileManager.default.replaceItemAt(url, withItemAt: tmp)
+        // Run file I/O on a background thread so we don't block the NIO event loop.
+        try await withCheckedThrowingContinuation { (cont: CheckedContinuation<Void, Error>) in
+            DispatchQueue.global(qos: .userInitiated).async {
+                do {
+                    let url = URL(fileURLWithPath: body.path)
+                    try FileManager.default.createDirectory(
+                        at: url.deletingLastPathComponent(), withIntermediateDirectories: true)
+                    let tmp = url.deletingLastPathComponent()
+                        .appendingPathComponent(".\(url.lastPathComponent).tmp")
+                    try body.content.write(to: tmp, atomically: false, encoding: .utf8)
+                    _ = try FileManager.default.replaceItemAt(url, withItemAt: tmp)
+                    cont.resume()
+                } catch {
+                    cont.resume(throwing: error)
+                }
+            }
+        }
         return .noContent
     }
 
-    app.post("files", "create") { req -> HTTPStatus in
+    app.post("files", "create") { req async throws -> HTTPStatus in
         struct CR: Content { let parentPath: String; let fileName: String; let content: String }
         let b = try req.content.decode(CR.self)
         guard !b.parentPath.contains(".."), !b.fileName.contains("..") else { throw Abort(.forbidden) }
-        let dest = URL(fileURLWithPath: b.parentPath).appendingPathComponent(b.fileName)
-        guard !FileManager.default.fileExists(atPath: dest.path) else { throw Abort(.conflict) }
-        try b.content.write(to: dest, atomically: true, encoding: .utf8)
+        try await withCheckedThrowingContinuation { (cont: CheckedContinuation<Void, Error>) in
+            DispatchQueue.global(qos: .userInitiated).async {
+                do {
+                    let dest = URL(fileURLWithPath: b.parentPath).appendingPathComponent(b.fileName)
+                    guard !FileManager.default.fileExists(atPath: dest.path) else {
+                        cont.resume(throwing: Abort(.conflict)); return
+                    }
+                    try b.content.write(to: dest, atomically: true, encoding: .utf8)
+                    cont.resume()
+                } catch {
+                    cont.resume(throwing: error)
+                }
+            }
+        }
         return .created
     }
 
-    app.post("files", "rename") { req -> HTTPStatus in
+    app.post("files", "rename") { req async throws -> HTTPStatus in
         struct RR: Content { let path: String; let newName: String }
         let b = try req.content.decode(RR.self)
         guard !b.path.contains("..") else { throw Abort(.forbidden) }
-        let src  = URL(fileURLWithPath: b.path)
-        let dest = src.deletingLastPathComponent().appendingPathComponent(b.newName)
-        try FileManager.default.moveItem(at: src, to: dest)
+        // Validate newName: no path separators or traversal sequences.
+        guard !b.newName.contains("/"), !b.newName.contains("\\"),
+              !b.newName.contains(".."), !b.newName.isEmpty else {
+            throw Abort(.forbidden, reason: "Invalid file name")
+        }
+        try await withCheckedThrowingContinuation { (cont: CheckedContinuation<Void, Error>) in
+            DispatchQueue.global(qos: .userInitiated).async {
+                do {
+                    let src  = URL(fileURLWithPath: b.path)
+                    let dest = src.deletingLastPathComponent().appendingPathComponent(b.newName)
+                    try FileManager.default.moveItem(at: src, to: dest)
+                    cont.resume()
+                } catch {
+                    cont.resume(throwing: error)
+                }
+            }
+        }
         return .ok
     }
 
-    app.delete("files", "delete") { req -> HTTPStatus in
+    app.delete("files", "delete") { req async throws -> HTTPStatus in
         guard let path = req.query[String.self, at: "path"] else { throw Abort(.badRequest) }
         guard !path.contains("..") else { throw Abort(.forbidden) }
-        try FileManager.default.removeItem(atPath: path)
+        try await withCheckedThrowingContinuation { (cont: CheckedContinuation<Void, Error>) in
+            DispatchQueue.global(qos: .userInitiated).async {
+                do {
+                    var isDir: ObjCBool = false
+                    guard FileManager.default.fileExists(atPath: path, isDirectory: &isDir) else {
+                        cont.resume(throwing: Abort(.notFound)); return
+                    }
+                    // Only delete files — refuse directory deletions to prevent mass data loss.
+                    guard !isDir.boolValue else {
+                        cont.resume(throwing: Abort(.forbidden, reason: "Directory deletion not allowed")); return
+                    }
+                    try FileManager.default.removeItem(atPath: path)
+                    cont.resume()
+                } catch {
+                    cont.resume(throwing: error)
+                }
+            }
+        }
         return .noContent
     }
 
@@ -73,7 +139,8 @@ func routes(_ app: Application) throws {
         let sessionId = UUID().uuidString
         let session   = BuildSession(id: sessionId, logger: req.logger)
         await BuildSessionStore.shared.create(session: session)
-        req.application.daemonController?.buildStarted(scheme: buildReq.scheme)
+        let scheme = buildReq.scheme
+        Task { @MainActor in req.application.daemonController?.buildStarted(scheme: scheme) }
         let host  = req.headers.first(name: .host) ?? "localhost:8080"
         let wsURL = "ws://\(host)/build/stream/\(sessionId)"
         Task {
@@ -91,11 +158,24 @@ func routes(_ app: Application) throws {
             try? await ws.close()
             return
         }
-        req.application.daemonController?.clientConnected(sessionId: sid, type: .build)
+        Task { @MainActor in req.application.daemonController?.clientConnected(sessionId: sid, type: .build) }
         session.addClient(ws)
         // Suspend until the client disconnects
         try? await ws.onClose.get()
-        req.application.daemonController?.clientDisconnected(sessionId: sid)
+        // Cancel xcodebuild if still running when client disconnects mid-build.
+        session.cancelBuild()
+        Task { @MainActor in req.application.daemonController?.clientDisconnected(sessionId: sid) }
+    }
+
+    // MARK: - Build Cancel
+
+    app.post("build", "cancel", ":sessionId") { req async -> HTTPStatus in
+        guard let sid = req.parameters.get("sessionId"),
+              let session = await BuildSessionStore.shared.session(for: sid) else {
+            throw Abort(.notFound)
+        }
+        session.cancelBuild()
+        return .accepted
     }
 
     // MARK: - LSP
@@ -121,28 +201,43 @@ func routes(_ app: Application) throws {
 
     // MARK: - System Health
 
-    app.get("system", "xcodegen-check") { _ -> HTTPStatus in
-        let p = Process()
-        p.executableURL = URL(fileURLWithPath: "/bin/zsh")
-        p.arguments     = ["-lc", "which xcodegen"]
-        p.standardOutput = Pipe()
-        p.standardError  = Pipe()
-        try? p.run(); p.waitUntilExit()
-        return p.terminationStatus == 0 ? .ok : .notFound
+    app.get("system", "xcodegen-check") { _ async -> HTTPStatus in
+        // Run on a background thread — waitUntilExit() blocks and must not run on NIO event loop.
+        await withCheckedContinuation { cont in
+            DispatchQueue.global(qos: .utility).async {
+                let p = Process()
+                p.executableURL = URL(fileURLWithPath: "/bin/zsh")
+                p.arguments     = ["-lc", "which xcodegen"]
+                p.standardOutput = Pipe(); p.standardError = Pipe()
+                try? p.run(); p.waitUntilExit()
+                cont.resume(returning: p.terminationStatus == 0 ? HTTPStatus.ok : .notFound)
+            }
+        }
     }
 
-    app.get("system", "disk-space") { req -> Response in
-        let url    = URL(fileURLWithPath: NSHomeDirectory())
-        let values = try? url.resourceValues(forKeys: [.volumeAvailableCapacityKey])
-        let free   = Int64(values?.volumeAvailableCapacity ?? 0)
-        let body   = try JSONEncoder().encode(["freeBytes": free])
+    app.get("system", "disk-space") { req async -> Response in
+        let (free, body) = await withCheckedContinuation { cont in
+            DispatchQueue.global(qos: .utility).async {
+                let url    = URL(fileURLWithPath: NSHomeDirectory())
+                let values = try? url.resourceValues(forKeys: [.volumeAvailableCapacityKey])
+                let free   = Int64(values?.volumeAvailableCapacity ?? 0)
+                let body   = (try? JSONEncoder().encode(["freeBytes": free])) ?? Data()
+                cont.resume(returning: (free, body))
+            }
+        }
         return Response(status: .ok,
                         headers: ["Content-Type": "application/json"],
                         body: .init(data: body))
     }
 
     app.get("system", "validate") { req -> Response in
-        let checks = DaemonStartupValidator.run()
+        // DaemonStartupValidator.run() executes multiple shell commands with
+        // waitUntilExit() — must run off the NIO event loop.
+        let checks: [StartupCheckResult] = await withCheckedContinuation { cont in
+            DispatchQueue.global(qos: .utility).async {
+                cont.resume(returning: DaemonStartupValidator.run())
+            }
+        }
         let body   = try JSONEncoder().encode(checks)
         return Response(status: .ok,
                         headers: ["Content-Type": "application/json"],
@@ -189,16 +284,22 @@ private func runBuildPipeline(
 
     let ddPath   = "/tmp/padxcode-derived-\(abs(request.projectPath.hashValue))"
     let teamID   = loadTeamID()
+    // Only include -destination if non-empty. An empty destination (build-only mode)
+    // would cause xcodebuild to error immediately with "destination is required".
+    let destinationArgs: [String] = request.destination.isEmpty
+        ? []
+        : ["-destination", request.destination]
     let args     = projectArg + [
         "-scheme",        request.scheme,
-        "-destination",   request.destination,
+    ] + destinationArgs + [
         "-configuration", request.configuration,
         "-derivedDataPath", ddPath,
         "CODE_SIGN_IDENTITY=Apple Development",
         "DEVELOPMENT_TEAM=\(teamID)",
-        "-allowProvisioningUpdates",
         "-hideShellScriptEnvironment",
-    ] + request.extraBuildSettings + ["build"]
+    ] + (UserDefaults.standard.object(forKey: "allowProvisioningUpdates") as? Bool ?? true
+        ? ["-allowProvisioningUpdates"] : [])
+      + request.extraBuildSettings + ["build"]
 
     let exitCode = await session.runXcodebuild(arguments: args)
 
@@ -232,7 +333,7 @@ private func runBuildPipeline(
 
 // MARK: - Helpers
 
-private func buildFileTree(at path: String) throws -> FileNode {
+private func buildFileTree(at path: String, depth: Int = 0) throws -> FileNode {
     let url = URL(fileURLWithPath: path)
     var isDir: ObjCBool = false
     guard FileManager.default.fileExists(atPath: path, isDirectory: &isDir) else {
@@ -241,6 +342,10 @@ private func buildFileTree(at path: String) throws -> FileNode {
     if !isDir.boolValue {
         return FileNode(name: url.lastPathComponent, path: path, isDirectory: false, children: nil)
     }
+    // Hard depth cap — prevents stack overflow on symlink loops or unusually deep trees.
+    guard depth < 12 else {
+        return FileNode(name: url.lastPathComponent, path: path, isDirectory: true, children: nil)
+    }
     let ignored: Set<String> = [
         ".git", ".build", "DerivedData", ".DS_Store",
         "node_modules", ".swiftpm", "Pods", "xcuserdata"
@@ -250,7 +355,7 @@ private func buildFileTree(at path: String) throws -> FileNode {
     let children: [FileNode] = try contents
         .filter { !ignored.contains($0.lastPathComponent) && !$0.lastPathComponent.hasPrefix(".") }
         .sorted { $0.lastPathComponent.localizedStandardCompare($1.lastPathComponent) == .orderedAscending }
-        .map    { try buildFileTree(at: $0.path) }
+        .map    { try buildFileTree(at: $0.path, depth: depth + 1) }
     return FileNode(name: url.lastPathComponent, path: path, isDirectory: true, children: children)
 }
 

Preferences/AppPreferences.swift

@@ -2,6 +2,7 @@ import Foundation
 import ServiceManagement
 import AppKit
 
+@MainActor
 final class AppPreferences: ObservableObject {
 
     @Published var port: Int {
@@ -34,8 +35,15 @@ final class AppPreferences: ObservableObject {
         }
     }
 
-    var tailscaleIP: String {
-        TailscaleDetector.currentIP() ?? "Not detected"
+    // Cached to avoid blocking the main thread on every view render.
+    // Refreshed once at init and when explicitly requested.
+    @Published private(set) var tailscaleIP: String = "Not detected"
+
+    func refreshTailscaleIP() {
+        DispatchQueue.global(qos: .utility).async {
+            let ip = TailscaleDetector.currentIP() ?? "Not detected"
+            DispatchQueue.main.async { self.tailscaleIP = ip }
+        }
     }
 
     init() {
@@ -46,12 +54,11 @@ final class AppPreferences: ObservableObject {
         self.allowProvisioningUpdates = d.object(forKey: "allowProvisioningUpdates") as? Bool ?? true
         self.buildConfiguration       = d.string(forKey: "buildConfiguration") ?? "Debug"
         applyDockPolicy()
+        Task { refreshTailscaleIP() }
     }
 
     private func applyDockPolicy() {
-        DispatchQueue.main.async {
-            NSApp.setActivationPolicy(self.showInDock ? .regular : .accessory)
-        }
+        NSApp.setActivationPolicy(showInDock ? .regular : .accessory)
     }
 }
 

UI/DaemonLogWindowView.swift

@@ -1,7 +1,7 @@
 import SwiftUI
 
 struct DaemonLogWindowView: View {
-    @Bindable var controller: DaemonController
+    @ObservedObject var controller: DaemonController
     @State private var filterLevel: DaemonLogLine.Level? = nil
     @State private var searchText = ""
     @State private var autoscroll = true

UI/DaemonSettingsView.swift

@@ -2,7 +2,7 @@ import SwiftUI
 import ServiceManagement
 
 struct DaemonSettingsView: View {
-    @Bindable var controller: DaemonController
+    @ObservedObject var controller: DaemonController
     @ObservedObject var preferences: AppPreferences
     @State private var pendingPort = ""
     @State private var showRestartAlert = false
@@ -14,7 +14,7 @@ struct DaemonSettingsView: View {
             generalTab.tabItem { Label("General", systemImage:"gearshape") }
         }
         .padding(20).frame(width:520)
-        .onAppear { pendingPort = String(preferences.port) }
+        .onAppear { pendingPort = String(preferences.port); preferences.refreshTailscaleIP() }
         .alert("Restart Required", isPresented:$showRestartAlert) {
             Button("Restart Now") { Task { await controller.applyPortChange() } }
             Button("Later", role:.cancel) {}

UI/MenuBarView.swift

@@ -1,7 +1,7 @@
 import SwiftUI
 
 struct MenuBarView: View {
-    @Bindable var controller: DaemonController
+    @ObservedObject var controller: DaemonController
     @ObservedObject var preferences: AppPreferences
     @Environment(\.openWindow) private var openWindow
 
@@ -30,9 +30,23 @@ struct MenuBarView: View {
                 Text(controller.serverState.statusLabel).font(.subheadline).foregroundStyle(.secondary)
             }
             Spacer()
-            Button { Task { if controller.serverState.isRunning { await controller.stop() } else { await controller.start() } } }
-            label: { Text(controller.serverState.isRunning ? "Stop" : "Start").frame(width:44) }
-            .buttonStyle(.bordered).controlSize(.small).tint(controller.serverState.isRunning ? .red : .green)
+            Button {
+                Task {
+                    if controller.serverState.isRunning { await controller.stop() }
+                    else if case .starting = controller.serverState { } // ignore during startup
+                    else { await controller.start() }
+                }
+            }
+            label: {
+                if case .starting = controller.serverState {
+                    ProgressView().scaleEffect(0.6).frame(width:44)
+                } else {
+                    Text(controller.serverState.isRunning ? "Stop" : "Start").frame(width:44)
+                }
+            }
+            .buttonStyle(.bordered).controlSize(.small)
+            .tint(controller.serverState.isRunning ? .red : .green)
+            .disabled({ if case .starting = controller.serverState { return true }; return false }())
         }
     }