fix: send deny on PairingApprovalWindow close and supersede

clients/macos/vellum-assistant/Features/Settings/PairingApprovalWindow.swift

@@ -8,19 +8,25 @@ import VellumAssistantShared
 final class PairingApprovalWindow {
     private var window: NSWindow?
     private let daemonClient: DaemonClient
+    private var currentPairingRequestId: String?
+    private var responseSent: Bool = false
+    private var windowDelegate: WindowCloseDelegate?
 
     init(daemonClient: DaemonClient) {
         self.daemonClient = daemonClient
     }
 
     /// Show the pairing approval prompt for a specific device.
     /// If a window is already showing, it is closed first (one prompt at a time).
+    /// Closing the previous window sends a deny for the superseded request.
     func show(pairingRequestId: String, deviceName: String) {
-        // Close any existing prompt before showing a new one
+        // Close any existing prompt before showing a new one.
+        // This will send a deny for the previous request if unanswered.
         close()
 
         let view = PairingApprovalView(deviceName: deviceName) { [weak self] decision in
             guard let self else { return }
+            self.responseSent = true
             try? self.daemonClient.sendPairingApprovalResponse(
                 pairingRequestId: pairingRequestId,
                 decision: decision
@@ -43,18 +49,65 @@ final class PairingApprovalWindow {
         window.isReleasedWhenClosed = false
         window.center()
 
+        // Delegate catches X-button close and sends deny if no response was sent.
+        let delegate = WindowCloseDelegate { [weak self] in
+            self?.handleWindowClosed()
+        }
+        window.delegate = delegate
+        self.windowDelegate = delegate
+
         window.makeKeyAndOrderFront(nil)
         NSApp.activate(ignoringOtherApps: true)
 
         self.window = window
+        self.currentPairingRequestId = pairingRequestId
+        self.responseSent = false
     }
 
     var isVisible: Bool {
         window?.isVisible ?? false
     }
 
     func close() {
+        denyIfNeeded()
         window?.close()
         window = nil
+        windowDelegate = nil
+    }
+
+    // MARK: - Private
+
+    /// Sends a deny for the current request if no explicit response has been sent yet.
+    private func denyIfNeeded() {
+        guard let requestId = currentPairingRequestId, !responseSent else { return }
+        responseSent = true
+        try? daemonClient.sendPairingApprovalResponse(
+            pairingRequestId: requestId,
+            decision: "deny"
+        )
+    }
+
+    /// Called by the window delegate when the user clicks the X button.
+    private func handleWindowClosed() {
+        denyIfNeeded()
+        window = nil
+        windowDelegate = nil
+    }
+}
+
+// MARK: - WindowCloseDelegate
+
+/// Lightweight NSWindowDelegate that forwards windowWillClose to a closure.
+private final class WindowCloseDelegate: NSObject, NSWindowDelegate {
+    private let onClose: @MainActor () -> Void
+
+    init(onClose: @escaping @MainActor () -> Void) {
+        self.onClose = onClose
+    }
+
+    func windowWillClose(_ notification: Notification) {
+        MainActor.assumeIsolated {
+            onClose()
+        }
     }
 }