diff --git a/NucleicRemote/NucleicRemote/Views/PairingScannerView.swift b/NucleicRemote/NucleicRemote/Views/PairingScannerView.swift
index f4db3ff..2d68a78 100644
--- a/NucleicRemote/NucleicRemote/Views/PairingScannerView.swift
+++ b/NucleicRemote/NucleicRemote/Views/PairingScannerView.swift
@@ -1,6 +1,11 @@
 import SwiftUI
 import AVFoundation
 import NucleicProtocol
+import os
+
+/// Filterable scanner diagnostics — in Console.app / Xcode, filter by subsystem
+/// `com.nucleic.remote` (category `scanner`) or search the "📷" marker.
+private let scannerLog = Logger(subsystem: "com.nucleic.remote", category: "scanner")
 
 /// Why the live camera feed isn't showing, so the scanner never sits on a silent black screen.
 enum ScannerCameraState: Equatable {
@@ -127,13 +132,24 @@ final class QRScannerController: UIViewController, AVCaptureMetadataOutputObject
         previewView.previewLayer.session = session
         previewView.previewLayer.videoGravity = .resizeAspectFill
 
+        let nc = NotificationCenter.default
+        nc.addObserver(self, selector: #selector(sessionDidStart),
+                       name: .AVCaptureSessionDidStartRunning, object: session)
+        nc.addObserver(self, selector: #selector(sessionRuntimeError(_:)),
+                       name: .AVCaptureSessionRuntimeError, object: session)
+        nc.addObserver(self, selector: #selector(sessionInterrupted(_:)),
+                       name: .AVCaptureSessionWasInterrupted, object: session)
+
         // Gate on camera authorization first — without this the prompt may never appear and the
         // feed silently fails (and on a denied device it would just stay black).
-        switch AVCaptureDevice.authorizationStatus(for: .video) {
+        let status = AVCaptureDevice.authorizationStatus(for: .video)
+        scannerLog.notice("📷 authorization status=\(status.rawValue, privacy: .public)")
+        switch status {
         case .authorized:
             configureSession()
         case .notDetermined:
             AVCaptureDevice.requestAccess(for: .video) { [weak self] granted in
+                scannerLog.notice("📷 requestAccess granted=\(granted, privacy: .public)")
                 granted ? self?.configureSession() : self?.report(.denied)
             }
         case .denied, .restricted:
@@ -149,27 +165,57 @@ final class QRScannerController: UIViewController, AVCaptureMetadataOutputObject
         sessionQueue.async { [weak self] in
             guard let self else { return }
             self.session.beginConfiguration()
-            guard let device = AVCaptureDevice.default(for: .video),
-                  let input = try? AVCaptureDeviceInput(device: device),
-                  self.session.canAddInput(input) else {
-                self.session.commitConfiguration(); self.report(.unavailable); return
+            if self.session.canSetSessionPreset(.high) { self.session.sessionPreset = .high }
+            guard let device = AVCaptureDevice.default(for: .video) else {
+                self.session.commitConfiguration()
+                scannerLog.error("📷 no video device — reporting unavailable")
+                self.report(.unavailable); return
+            }
+            scannerLog.notice("📷 device=\(device.localizedName, privacy: .public)")
+            guard let input = try? AVCaptureDeviceInput(device: device), self.session.canAddInput(input) else {
+                self.session.commitConfiguration()
+                scannerLog.error("📷 cannot create/add camera input")
+                self.report(.unavailable); return
             }
             self.session.addInput(input)
 
             let output = AVCaptureMetadataOutput()
             guard self.session.canAddOutput(output) else {
-                self.session.commitConfiguration(); self.report(.unavailable); return
+                self.session.commitConfiguration()
+                scannerLog.error("📷 cannot add metadata output")
+                self.report(.unavailable); return
             }
             self.session.addOutput(output)
             output.setMetadataObjectsDelegate(self, queue: .main)
-            output.metadataObjectTypes = [.qr]
             self.session.commitConfiguration()
+            // availableMetadataObjectTypes is only populated after the output is connected.
+            output.metadataObjectTypes = output.availableMetadataObjectTypes.contains(.qr)
+                ? [.qr] : output.availableMetadataObjectTypes
 
             self.session.startRunning()
+            scannerLog.notice("📷 startRunning -> isRunning=\(self.session.isRunning, privacy: .public) inputs=\(self.session.inputs.count, privacy: .public) outputs=\(self.session.outputs.count, privacy: .public)")
             self.report(.scanning)
         }
     }
 
+    @objc private func sessionDidStart() {
+        DispatchQueue.main.async { [weak self] in
+            guard let self else { return }
+            let connection = self.previewView.previewLayer.connection
+            scannerLog.notice("📷 didStartRunning: previewConnection=\(connection != nil, privacy: .public) active=\(connection?.isActive ?? false, privacy: .public) enabled=\(connection?.isEnabled ?? false, privacy: .public) viewBounds=\(self.view.bounds.debugDescription, privacy: .public) layerBounds=\(self.previewView.previewLayer.bounds.debugDescription, privacy: .public)")
+        }
+    }
+
+    @objc private func sessionRuntimeError(_ note: Notification) {
+        let error = note.userInfo?[AVCaptureSessionErrorKey] as? NSError
+        scannerLog.error("📷 runtimeError=\(error?.description ?? "nil", privacy: .public)")
+    }
+
+    @objc private func sessionInterrupted(_ note: Notification) {
+        let reason = (note.userInfo?[AVCaptureSessionInterruptionReasonKey] as? Int) ?? -1
+        scannerLog.error("📷 sessionInterrupted reason=\(reason, privacy: .public)")
+    }
+
     override func viewDidDisappear(_ animated: Bool) {
         super.viewDidDisappear(animated)
         sessionQueue.async { [session] in if session.isRunning { session.stopRunning() } }