Initial commit: FieldLogger MAUI app with Maglink BLE support

Added Maglink RTK GNSS receiver integration with correct BLE UUIDs and device name filtering (ML-* prefix). 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
2026-07-06 13:46:50 -05:00
commit b602b762c9
79 changed files with 5807 additions and 0 deletions
--- a/FieldLogger/App.xaml
+++ b/FieldLogger/App.xaml
@@ -0,0 +1,21 @@
+<?xml version = "1.0" encoding = "UTF-8" ?>
+<Application xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             xmlns:local="clr-namespace:FieldLogger"
+             xmlns:conv="clr-namespace:FieldLogger.Converters"
+             x:Class="FieldLogger.App">
+    <Application.Resources>
+        <ResourceDictionary>
+            <ResourceDictionary.MergedDictionaries>
+                <ResourceDictionary Source="Resources/Styles/Colors.xaml" />
+                <ResourceDictionary Source="Resources/Styles/Styles.xaml" />
+            </ResourceDictionary.MergedDictionaries>
+
+            <conv:ConnectionStateToColorConverter x:Key="StateColor" />
+            <conv:ConnectionStateToTextConverter x:Key="StateText" />
+            <conv:UtilityToNameConverter x:Key="UtilityName" />
+            <conv:FixStatusToNameConverter x:Key="FixStatusName" />
+            <conv:InvertBoolConverter x:Key="InvertBool" />
+        </ResourceDictionary>
+    </Application.Resources>
+</Application>
--- a/FieldLogger/App.xaml.cs
+++ b/FieldLogger/App.xaml.cs
@@ -0,0 +1,14 @@
+namespace FieldLogger;
+
+public partial class App : Application
+{
+	public App()
+	{
+		InitializeComponent();
+	}
+
+	protected override Window CreateWindow(IActivationState? activationState)
+	{
+		return new Window(new AppShell());
+	}
+}
--- a/FieldLogger/AppShell.xaml
+++ b/FieldLogger/AppShell.xaml
@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<Shell
+    x:Class="FieldLogger.AppShell"
+    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+    xmlns:views="clr-namespace:FieldLogger.Views"
+    Title="Field Logger">
+
+    <TabBar>
+        <ShellContent Title="Home" Route="home" ContentTemplate="{DataTemplate views:HomePage}" />
+        <ShellContent Title="Jobs" Route="jobs" ContentTemplate="{DataTemplate views:JobsPage}" />
+        <ShellContent Title="Map" Route="map" ContentTemplate="{DataTemplate views:MapPage}" />
+        <ShellContent Title="Settings" Route="settings" ContentTemplate="{DataTemplate views:SettingsPage}" />
+    </TabBar>
+
+</Shell>
--- a/FieldLogger/AppShell.xaml.cs
+++ b/FieldLogger/AppShell.xaml.cs
@@ -0,0 +1,14 @@
+using FieldLogger.Views;
+
+namespace FieldLogger;
+
+public partial class AppShell : Shell
+{
+    public AppShell()
+    {
+        InitializeComponent();
+
+        Routing.RegisterRoute("devicescan", typeof(DeviceScanPage));
+        Routing.RegisterRoute("jobdetail", typeof(JobDetailPage));
+    }
+}
--- a/FieldLogger/Converters/AppConverters.cs
+++ b/FieldLogger/Converters/AppConverters.cs
@@ -0,0 +1,68 @@
+using System.Globalization;
+using FieldLogger.Models;
+using FieldLogger.Services;
+
+namespace FieldLogger.Converters;
+
+public sealed class ConnectionStateToColorConverter : IValueConverter
+{
+    public object Convert(object? value, Type targetType, object? parameter, CultureInfo culture) =>
+        value switch
+        {
+            ConnectionState.Connected => Colors.LimeGreen,
+            ConnectionState.Connecting => Colors.Orange,
+            _ => Colors.IndianRed,
+        };
+
+    public object ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+        => throw new NotSupportedException();
+}
+
+public sealed class ConnectionStateToTextConverter : IValueConverter
+{
+    public object Convert(object? value, Type targetType, object? parameter, CultureInfo culture) =>
+        value switch
+        {
+            ConnectionState.Connected => "Connected",
+            ConnectionState.Connecting => "Connecting…",
+            _ => "Disconnected",
+        };
+
+    public object ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+        => throw new NotSupportedException();
+}
+
+public sealed class UtilityToNameConverter : IValueConverter
+{
+    public object Convert(object? value, Type targetType, object? parameter, CultureInfo culture) =>
+        value is int i ? ((UmUtility)i).ToString() : "";
+
+    public object ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+        => throw new NotSupportedException();
+}
+
+public sealed class InvertBoolConverter : IValueConverter
+{
+    public object Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+        => value is bool b && !b;
+
+    public object ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+        => value is bool b && !b;
+}
+
+public sealed class FixStatusToNameConverter : IValueConverter
+{
+    public object Convert(object? value, Type targetType, object? parameter, CultureInfo culture) =>
+        value is int i ? (GnssFixStatus)i switch
+        {
+            GnssFixStatus.NoFix => "No Fix",
+            GnssFixStatus.Single => "Single",
+            GnssFixStatus.Dgps => "DGPS",
+            GnssFixStatus.RtkFixed => "RTK Fixed",
+            GnssFixStatus.RtkFloat => "RTK Float",
+            _ => "?",
+        } : "—";
+
+    public object ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+        => throw new NotSupportedException();
+}
--- a/FieldLogger/FieldLogger.csproj
+++ b/FieldLogger/FieldLogger.csproj
@@ -0,0 +1,82 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+	<PropertyGroup>
+		<TargetFrameworks>net9.0-android;net9.0-ios;net9.0-maccatalyst</TargetFrameworks>
+		<TargetFrameworks Condition="$([MSBuild]::IsOSPlatform('windows'))">$(TargetFrameworks);net9.0-windows10.0.19041.0</TargetFrameworks>
+		<!-- Uncomment to also build the tizen app. You will need to install tizen by following this: https://github.com/Samsung/Tizen.NET -->
+		<!-- <TargetFrameworks>$(TargetFrameworks);net9.0-tizen</TargetFrameworks> -->
+
+		<!-- Note for MacCatalyst:
+		The default runtime is maccatalyst-x64, except in Release config, in which case the default is maccatalyst-x64;maccatalyst-arm64.
+		When specifying both architectures, use the plural <RuntimeIdentifiers> instead of the singular <RuntimeIdentifier>.
+		The Mac App Store will NOT accept apps with ONLY maccatalyst-arm64 indicated;
+		either BOTH runtimes must be indicated or ONLY macatalyst-x64. -->
+		<!-- For example: <RuntimeIdentifiers>maccatalyst-x64;maccatalyst-arm64</RuntimeIdentifiers> -->
+
+		<OutputType>Exe</OutputType>
+		<RootNamespace>FieldLogger</RootNamespace>
+		<UseMaui>true</UseMaui>
+		<SingleProject>true</SingleProject>
+		<ImplicitUsings>enable</ImplicitUsings>
+		<Nullable>enable</Nullable>
+
+		<!-- MVVMTK0045: [ObservableProperty] on fields is not WinRT-AOT compatible. This app is not
+		     published with native AOT on Windows; revisit if that changes (needs LangVersion=preview
+		     partial properties). -->
+		<NoWarn>$(NoWarn);MVVMTK0045</NoWarn>
+
+		<!-- Display name -->
+		<ApplicationTitle>Field Logger</ApplicationTitle>
+
+		<!-- App Identifier -->
+		<ApplicationId>com.undergroundmagnetics.fieldlogger</ApplicationId>
+
+		<!-- Versions -->
+		<ApplicationDisplayVersion>1.0</ApplicationDisplayVersion>
+		<ApplicationVersion>1</ApplicationVersion>
+
+		<!-- To develop, package, and publish an app to the Microsoft Store, see: https://aka.ms/MauiTemplateUnpackaged -->
+		<WindowsPackageType>None</WindowsPackageType>
+
+		<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'ios'">15.0</SupportedOSPlatformVersion>
+		<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'maccatalyst'">15.0</SupportedOSPlatformVersion>
+		<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'android'">21.0</SupportedOSPlatformVersion>
+		<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'windows'">10.0.17763.0</SupportedOSPlatformVersion>
+		<TargetPlatformMinVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'windows'">10.0.17763.0</TargetPlatformMinVersion>
+		<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'tizen'">6.5</SupportedOSPlatformVersion>
+	</PropertyGroup>
+
+	<ItemGroup>
+		<!-- App Icon -->
+		<MauiIcon Include="Resources\AppIcon\appicon.svg" ForegroundFile="Resources\AppIcon\appiconfg.svg" Color="#512BD4" />
+
+		<!-- Splash Screen -->
+		<MauiSplashScreen Include="Resources\Splash\splash.svg" Color="#512BD4" BaseSize="128,128" />
+
+		<!-- Images -->
+		<MauiImage Include="Resources\Images\*" />
+		<MauiImage Update="Resources\Images\dotnet_bot.png" Resize="True" BaseSize="300,185" />
+		
+		<!-- Custom Fonts -->
+		<MauiFont Include="Resources\Fonts\*" />
+
+		<!-- Raw Assets (also remove the "Resources\Raw" prefix) -->
+		<MauiAsset Include="Resources\Raw\**" LogicalName="%(RecursiveDir)%(Filename)%(Extension)" />
+	</ItemGroup>
+
+	<ItemGroup>
+		<PackageReference Include="Microsoft.Maui.Controls" Version="$(MauiVersion)" />
+		<PackageReference Include="Microsoft.Extensions.Logging.Debug" Version="9.0.5" />
+		<PackageReference Include="CommunityToolkit.Mvvm" Version="8.4.0" />
+		<PackageReference Include="Plugin.BLE" Version="3.1.0" />
+		<PackageReference Include="sqlite-net-pcl" Version="1.9.172" />
+		<PackageReference Include="SQLitePCLRaw.bundle_green" Version="2.1.10" />
+	</ItemGroup>
+
+	<!-- Native map control (Google Maps on Android, Apple Maps on iOS/macOS). Not available on Windows,
+	     where MapPage falls back to a Google Maps JavaScript WebView instead. -->
+	<ItemGroup Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) != 'windows'">
+		<PackageReference Include="Microsoft.Maui.Controls.Maps" Version="$(MauiVersion)" />
+	</ItemGroup>
+
+</Project>
--- a/FieldLogger/GlobalXmlns.cs
+++ b/FieldLogger/GlobalXmlns.cs
@@ -0,0 +1,2 @@
+[assembly: XmlnsDefinition("http://schemas.microsoft.com/dotnet/maui/global", "FieldLogger")]
+[assembly: XmlnsDefinition("http://schemas.microsoft.com/dotnet/maui/global", "FieldLogger.Pages")]
--- a/FieldLogger/MauiProgram.cs
+++ b/FieldLogger/MauiProgram.cs
@@ -0,0 +1,64 @@
+using FieldLogger.Services;
+using FieldLogger.Services.Ble;
+using FieldLogger.Services.Data;
+using FieldLogger.Services.Sync;
+using FieldLogger.ViewModels;
+using FieldLogger.Views;
+using Microsoft.Extensions.Logging;
+
+namespace FieldLogger;
+
+public static class MauiProgram
+{
+	public static MauiApp CreateMauiApp()
+	{
+		var builder = MauiApp.CreateBuilder();
+		builder
+			.UseMauiApp<App>()
+#if !WINDOWS
+			.UseMauiMaps()
+#endif
+			.ConfigureFonts(fonts =>
+			{
+				fonts.AddFont("OpenSans-Regular.ttf", "OpenSansRegular");
+				fonts.AddFont("OpenSans-Semibold.ttf", "OpenSansSemibold");
+			});
+
+#if DEBUG
+		builder.Logging.AddDebug();
+#endif
+
+		// Core services
+		builder.Services.AddSingleton<SettingsService>();
+		builder.Services.AddSingleton<AppDatabase>();
+		builder.Services.AddSingleton<BleScanner>();
+		builder.Services.AddSingleton<UmReceiverService>();
+		builder.Services.AddSingleton<MaglinkService>();
+		builder.Services.AddSingleton<DeviceConnectionManager>();
+		builder.Services.AddSingleton<PointLogger>();
+		builder.Services.AddSingleton<IMqttSyncService, NullMqttSyncService>();
+
+		// View models
+		builder.Services.AddSingleton<HomeViewModel>();
+		builder.Services.AddSingleton<JobsViewModel>();
+		builder.Services.AddSingleton<MapViewModel>();
+		builder.Services.AddSingleton<SettingsViewModel>();
+		builder.Services.AddTransient<DeviceScanViewModel>();
+		builder.Services.AddTransient<JobDetailViewModel>();
+
+		// Pages
+		builder.Services.AddSingleton<HomePage>();
+		builder.Services.AddSingleton<JobsPage>();
+		builder.Services.AddSingleton<MapPage>();
+		builder.Services.AddSingleton<SettingsPage>();
+		builder.Services.AddTransient<DeviceScanPage>();
+		builder.Services.AddTransient<JobDetailPage>();
+
+		var app = builder.Build();
+
+		// Instantiate the point logger so it listens for receiver packets from startup.
+		_ = app.Services.GetRequiredService<PointLogger>();
+
+		return app;
+	}
+}
--- a/FieldLogger/Models/DeviceKind.cs
+++ b/FieldLogger/Models/DeviceKind.cs
@@ -0,0 +1,11 @@
+namespace FieldLogger.Models;
+
+/// <summary>The two kinds of BLE devices the app pairs with.</summary>
+public enum DeviceKind
+{
+    /// <summary>Underground Magnetics utility locating receiver (UMRX_* / DT100_*).</summary>
+    Locator,
+
+    /// <summary>Maglink RTK GNSS receiver (H11).</summary>
+    RtkGps,
+}
--- a/FieldLogger/Models/GnssFix.cs
+++ b/FieldLogger/Models/GnssFix.cs
@@ -0,0 +1,155 @@
+using System.Globalization;
+
+namespace FieldLogger.Models;
+
+public enum GnssFixStatus { NoFix = 0, Single = 1, Dgps = 2, RtkFixed = 4, RtkFloat = 5 }
+
+/// <summary>
+/// A parsed $GNPOS sentence from the Maglink (H11) RTK receiver.
+/// </summary>
+public sealed class GnssFix
+{
+    public double Latitude { get; init; }
+    public double Longitude { get; init; }
+    public double Altitude { get; init; }
+    public double AltitudeCorrected { get; init; }
+    public GnssFixStatus Status { get; init; }
+    public double Hdop { get; init; }
+    public double Hrms { get; init; }
+    public double Vrms { get; init; }
+    public int SatellitesUsed { get; init; }
+    public int SatellitesVisible { get; init; }
+    public double SpeedKmh { get; init; }
+    public double Heading { get; init; }
+    public double BatteryVoltage { get; init; }
+    public int BatteryPercent { get; init; }
+    public bool NtripConnected { get; init; }
+    public int RtcmSize { get; init; }
+    public double CorrectionAgeSeconds { get; init; }
+    public long UnixTimestamp { get; init; }
+    public double TiltAngle { get; init; }
+    public string RawSentence { get; init; } = "";
+
+    /// <summary>Local UTC time this fix was received by the app.</summary>
+    public DateTime ReceivedUtc { get; init; } = DateTime.UtcNow;
+
+    public bool HasPosition => Status != GnssFixStatus.NoFix;
+
+    public string StatusLabel => Status switch
+    {
+        GnssFixStatus.NoFix => "No Fix",
+        GnssFixStatus.Single => "Single",
+        GnssFixStatus.Dgps => "DGPS",
+        GnssFixStatus.RtkFixed => "RTK Fixed",
+        GnssFixStatus.RtkFloat => "RTK Float",
+        _ => Status.ToString(),
+    };
+
+    /// <summary>Parses a "$GNPOS,..." sentence (checksum must already be validated).</summary>
+    public static GnssFix? TryParse(string sentence)
+    {
+        var body = NmeaSentence.Body(sentence);
+        var f = body.Split(',');
+        if (f.Length < 20 || f[0] != "GNPOS")
+            return null;
+
+        try
+        {
+            return new GnssFix
+            {
+                Latitude = D(f[1]),
+                Longitude = D(f[2]),
+                Altitude = D(f[3]),
+                AltitudeCorrected = D(f[4]),
+                Status = (GnssFixStatus)I(f[5]),
+                Hdop = D(f[6]),
+                Hrms = D(f[7]),
+                Vrms = D(f[8]),
+                SatellitesUsed = I(f[9]),
+                SatellitesVisible = I(f[10]),
+                SpeedKmh = D(f[11]),
+                Heading = D(f[12]),
+                BatteryVoltage = D(f[13]),
+                BatteryPercent = I(f[14]),
+                NtripConnected = I(f[15]) != 0,
+                RtcmSize = I(f[16]),
+                CorrectionAgeSeconds = D(f[17]),
+                UnixTimestamp = long.Parse(f[18], CultureInfo.InvariantCulture),
+                TiltAngle = D(f[19]),
+                RawSentence = sentence.Trim(),
+            };
+        }
+        catch (FormatException)
+        {
+            return null;
+        }
+    }
+
+    private static double D(string s) => double.Parse(s, NumberStyles.Float, CultureInfo.InvariantCulture);
+    private static int I(string s) => int.Parse(s, CultureInfo.InvariantCulture);
+}
+
+/// <summary>
+/// A parsed $GNDEV device-information sentence from the Maglink receiver.
+/// </summary>
+public sealed class GnssDeviceInfo
+{
+    public string SerialNumber { get; init; } = "";
+    public string PcbVersion { get; init; } = "";
+    public string FirmwareVersion { get; init; } = "";
+    public string Imei { get; init; } = "";
+    public string Imsi { get; init; } = "";
+    public string Iccid { get; init; } = "";
+
+    public static GnssDeviceInfo? TryParse(string sentence)
+    {
+        var f = NmeaSentence.Body(sentence).Split(',');
+        if (f.Length < 7 || f[0] != "GNDEV")
+            return null;
+
+        return new GnssDeviceInfo
+        {
+            SerialNumber = f[1],
+            PcbVersion = f[2],
+            FirmwareVersion = f[3],
+            Imei = f[4],
+            Imsi = f[5],
+            Iccid = f[6],
+        };
+    }
+}
+
+/// <summary>NMEA framing helpers ($...*hh checksum).</summary>
+public static class NmeaSentence
+{
+    /// <summary>Returns the sentence body between '$' and '*' (or end of string).</summary>
+    public static string Body(string sentence)
+    {
+        var s = sentence.Trim().TrimStart('$');
+        var star = s.IndexOf('*');
+        return star >= 0 ? s[..star] : s;
+    }
+
+    public static byte Checksum(string sentence)
+    {
+        byte checksum = 0;
+        foreach (var c in Body(sentence))
+            checksum ^= (byte)c;
+        return checksum;
+    }
+
+    /// <summary>Validates the trailing *hh checksum. Sentences without a checksum fail validation.</summary>
+    public static bool VerifyChecksum(string sentence)
+    {
+        var star = sentence.LastIndexOf('*');
+        if (star < 0 || star + 3 > sentence.TrimEnd().Length)
+            return false;
+
+        var hex = sentence.Substring(star + 1, 2);
+        if (!byte.TryParse(hex, System.Globalization.NumberStyles.HexNumber,
+                System.Globalization.CultureInfo.InvariantCulture, out var expected))
+            return false;
+
+        return Checksum(sentence) == expected;
+    }
+}
--- a/FieldLogger/Models/Job.cs
+++ b/FieldLogger/Models/Job.cs
@@ -0,0 +1,23 @@
+using SQLite;
+
+namespace FieldLogger.Models;
+
+[Table("jobs")]
+public sealed class Job
+{
+    [PrimaryKey, AutoIncrement]
+    public int Id { get; set; }
+
+    [NotNull]
+    public string Name { get; set; } = "";
+
+    public string Notes { get; set; } = "";
+
+    public DateTime CreatedUtc { get; set; } = DateTime.UtcNow;
+
+    /// <summary>Reserved for MQTT sync: server-side job identifier once provisioned remotely.</summary>
+    public string? RemoteId { get; set; }
+
+    /// <summary>Reserved for MQTT sync: true once all points have been pushed to the server.</summary>
+    public bool Synced { get; set; }
+}
--- a/FieldLogger/Models/LoggedPoint.cs
+++ b/FieldLogger/Models/LoggedPoint.cs
@@ -0,0 +1,145 @@
+using SQLite;
+
+namespace FieldLogger.Models;
+
+/// <summary>
+/// One logged locate point: the full UM receiver PBDL packet joined with the
+/// GNSS fix that was current when the operator pressed the log button.
+/// </summary>
+[Table("points")]
+public sealed class LoggedPoint
+{
+    [PrimaryKey, AutoIncrement]
+    public int Id { get; set; }
+
+    [Indexed]
+    public int JobId { get; set; }
+
+    public DateTime TimestampUtc { get; set; } = DateTime.UtcNow;
+
+    // ---- UM locating receiver (PBDL schema 1) ----
+    public int Mode { get; set; }
+    public int Frequency { get; set; }
+    public int FreqType { get; set; }
+    public int Signal { get; set; }
+    public int GainDb { get; set; }
+    public string DepthRaw { get; set; } = "";
+    public double? DepthMeters { get; set; }
+    public string CurrentRaw { get; set; } = "";
+    public double? CurrentMilliamps { get; set; }
+    public int CompassAngle { get; set; }
+    public int GuidanceArrows { get; set; }
+    public int LdPhase { get; set; }
+    public bool Clipping { get; set; }
+    public int DepthCurrentSetting { get; set; }
+    public int LrArrowStyle { get; set; }
+    public int AudioVolume { get; set; }
+    public int AudioModulation { get; set; }
+    public int AudioSound { get; set; }
+    public double LocatorBatteryVoltage { get; set; }
+    public int LocatorBatteryType { get; set; }
+    public int Backlight { get; set; }
+    public int Utility { get; set; }
+    public bool MenuInUse { get; set; }
+    public string LocatorRawPacket { get; set; } = "";
+    public string LocatorSerialNumber { get; set; } = "";
+    public string LocatorModel { get; set; } = "";
+
+    // ---- GNSS fix (Maglink $GNPOS) ----
+    /// <summary>False when no fresh GNSS fix was available at log time; position fields are then unset.</summary>
+    public bool GpsValid { get; set; }
+    public double Latitude { get; set; }
+    public double Longitude { get; set; }
+    public double Altitude { get; set; }
+    public double AltitudeCorrected { get; set; }
+    public int FixStatus { get; set; }
+    public double Hdop { get; set; }
+    public double Hrms { get; set; }
+    public double Vrms { get; set; }
+    public int SatellitesUsed { get; set; }
+    public int SatellitesVisible { get; set; }
+    public double SpeedKmh { get; set; }
+    public double HeadingDegrees { get; set; }
+    public bool NtripConnected { get; set; }
+    public double CorrectionAgeSeconds { get; set; }
+    public long GpsUnixTimestamp { get; set; }
+    public double TiltAngle { get; set; }
+    public double GpsBatteryVoltage { get; set; }
+    public int GpsBatteryPercent { get; set; }
+    public string GpsRawSentence { get; set; } = "";
+    public string GpsSerialNumber { get; set; } = "";
+
+    /// <summary>Reserved for MQTT sync.</summary>
+    public bool Synced { get; set; }
+
+    [Ignore]
+    public GnssFixStatus FixStatusEnum => (GnssFixStatus)FixStatus;
+
+    [Ignore]
+    public UmUtility UtilityEnum => (UmUtility)Utility;
+
+    public static LoggedPoint From(int jobId, UmLogPacket packet, UmDeviceInfo? locatorInfo,
+        GnssFix? fix, GnssDeviceInfo? gpsInfo)
+    {
+        var p = new LoggedPoint
+        {
+            JobId = jobId,
+            TimestampUtc = DateTime.UtcNow,
+
+            Mode = (int)packet.Mode,
+            Frequency = packet.Frequency,
+            FreqType = (int)packet.FreqType,
+            Signal = packet.Signal,
+            GainDb = packet.GainDb,
+            DepthRaw = packet.DepthRaw,
+            DepthMeters = packet.DepthMeters,
+            CurrentRaw = packet.CurrentRaw,
+            CurrentMilliamps = packet.CurrentMilliamps,
+            CompassAngle = packet.CompassAngle,
+            GuidanceArrows = packet.GuidanceArrows,
+            LdPhase = packet.LdPhase,
+            Clipping = packet.Clipping,
+            DepthCurrentSetting = packet.DepthCurrentSetting,
+            LrArrowStyle = packet.LrArrowStyle,
+            AudioVolume = packet.AudioVolume,
+            AudioModulation = packet.AudioModulation,
+            AudioSound = packet.AudioSound,
+            LocatorBatteryVoltage = packet.BatteryVoltage,
+            LocatorBatteryType = (int)packet.BatteryType,
+            Backlight = packet.Backlight,
+            Utility = (int)packet.Utility,
+            MenuInUse = packet.MenuInUse,
+            LocatorRawPacket = packet.RawText,
+            LocatorSerialNumber = locatorInfo?.SerialNumber ?? "",
+            LocatorModel = locatorInfo?.ModelName ?? "",
+
+            GpsSerialNumber = gpsInfo?.SerialNumber ?? "",
+        };
+
+        if (fix is not null)
+        {
+            p.GpsValid = fix.HasPosition;
+            p.Latitude = fix.Latitude;
+            p.Longitude = fix.Longitude;
+            p.Altitude = fix.Altitude;
+            p.AltitudeCorrected = fix.AltitudeCorrected;
+            p.FixStatus = (int)fix.Status;
+            p.Hdop = fix.Hdop;
+            p.Hrms = fix.Hrms;
+            p.Vrms = fix.Vrms;
+            p.SatellitesUsed = fix.SatellitesUsed;
+            p.SatellitesVisible = fix.SatellitesVisible;
+            p.SpeedKmh = fix.SpeedKmh;
+            p.HeadingDegrees = fix.Heading;
+            p.NtripConnected = fix.NtripConnected;
+            p.CorrectionAgeSeconds = fix.CorrectionAgeSeconds;
+            p.GpsUnixTimestamp = fix.UnixTimestamp;
+            p.TiltAngle = fix.TiltAngle;
+            p.GpsBatteryVoltage = fix.BatteryVoltage;
+            p.GpsBatteryPercent = fix.BatteryPercent;
+            p.GpsRawSentence = fix.RawSentence;
+        }
+
+        return p;
+    }
+}
--- a/FieldLogger/Models/UmDeviceInfo.cs
+++ b/FieldLogger/Models/UmDeviceInfo.cs
@@ -0,0 +1,51 @@
+namespace FieldLogger.Models;
+
+/// <summary>
+/// Info string the UM receiver sends the first time push-button data logging is enabled.
+/// </summary>
+public sealed class UmDeviceInfo
+{
+    public string Manufacturer { get; init; } = "";
+    public string ModelName { get; init; } = "";
+    public string SerialNumber { get; init; } = "";
+    public string BootloaderVersion { get; init; } = "";
+    public string SoftwareVersion { get; init; } = "";
+    public string ManufactureDate { get; init; } = "";
+    public string CalibrationDate { get; init; } = "";
+    public double HourCount { get; init; }
+    public int PbdlSchema { get; init; }
+    public string RawText { get; init; } = "";
+
+    /// <summary>
+    /// Parses the 10-field info string (9 parameters followed by "OK").
+    /// Returns null if the line does not match.
+    /// </summary>
+    public static UmDeviceInfo? TryParse(string line)
+    {
+        var fields = line.Trim().Split(',');
+        if (fields.Length < 10 || !fields[^1].Trim().Equals("OK", StringComparison.OrdinalIgnoreCase))
+            return null;
+
+        // Serial number is 9 digits; use it to distinguish from other OK-terminated responses.
+        if (fields[2].Trim().Length < 6)
+            return null;
+
+        double.TryParse(fields[7], System.Globalization.NumberStyles.Float,
+            System.Globalization.CultureInfo.InvariantCulture, out var hours);
+        int.TryParse(fields[8], out var schema);
+
+        return new UmDeviceInfo
+        {
+            Manufacturer = fields[0].Trim(),
+            ModelName = fields[1].Trim(),
+            SerialNumber = fields[2].Trim(),
+            BootloaderVersion = fields[3].Trim(),
+            SoftwareVersion = fields[4].Trim(),
+            ManufactureDate = fields[5].Trim(),
+            CalibrationDate = fields[6].Trim(),
+            HourCount = hours,
+            PbdlSchema = schema,
+            RawText = line.Trim(),
+        };
+    }
+}
--- a/FieldLogger/Models/UmLogPacket.cs
+++ b/FieldLogger/Models/UmLogPacket.cs
@@ -0,0 +1,141 @@
+using System.Globalization;
+
+namespace FieldLogger.Models;
+
+public enum UmMode { Single = 0, Twin = 1, Null = 2, Sweep = 3, TwinSweep = 4, Omni = 5, TwinOmni = 6 }
+
+public enum UmFreqType { Active = 0, LdActive = 1, Power = 2, GroupedPower = 3, Cathodic = 4, Sonde = 5, Radio = 6, FaultFind = 7 }
+
+public enum UmUtility { None = 0, Gas = 1, Power = 2, Communications = 3, Water = 4, Sewer = 5, Fiber = 6, Other = 7 }
+
+public enum UmBatteryType { NotMeasured = 0, Alkaline = 1, AlkalineError = 2, Lithium = 3 }
+
+/// <summary>
+/// A single push-button data-log packet from the UM locating receiver
+/// (PBDL schema 1, 21 comma-delimited fields).
+/// </summary>
+public sealed class UmLogPacket
+{
+    public UmMode Mode { get; init; }
+    public int Frequency { get; init; }
+    public UmFreqType FreqType { get; init; }
+    public int Signal { get; init; }              // 0 - 99
+    public int GainDb { get; init; }              // 0 - 145 dB
+    public string DepthRaw { get; init; } = "";   // "X' Y\"" imperial, "X.Yym" metric, "- - -" no depth
+    public string CurrentRaw { get; init; } = ""; // 0 - 999mA
+    public int CompassAngle { get; init; }        // 0 - 180 degrees (direction ambiguous)
+    public int GuidanceArrows { get; init; }      // -300 to 300, negative = left
+    public int LdPhase { get; init; }
+    public bool Clipping { get; init; }
+    public int DepthCurrentSetting { get; init; } // 0 ON, 1 AUTO
+    public int LrArrowStyle { get; init; }        // 0 OFF, 1 Style 1, 2 Style 2
+    public int AudioVolume { get; init; }         // 0 - 3
+    public int AudioModulation { get; init; }     // 0 AM, 1 FM
+    public int AudioSound { get; init; }          // 0 Smooth, 1 Rough
+    public double BatteryVoltage { get; init; }
+    public UmBatteryType BatteryType { get; init; }
+    public int Backlight { get; init; }           // 0 Low, 1 Medium, 2 High
+    public UmUtility Utility { get; init; }
+    public bool MenuInUse { get; init; }
+    public string RawText { get; init; } = "";
+
+    public const int FieldCount = 21;
+
+    /// <summary>Depth converted to meters, when the raw string can be interpreted; otherwise null.</summary>
+    public double? DepthMeters => TryParseDepthMeters(DepthRaw);
+
+    /// <summary>Current in mA parsed from the raw string, when possible.</summary>
+    public double? CurrentMilliamps
+    {
+        get
+        {
+            var s = CurrentRaw.Trim().TrimEnd('A', 'a').TrimEnd('m', 'M');
+            return double.TryParse(s, NumberStyles.Float, CultureInfo.InvariantCulture, out var v) ? v : null;
+        }
+    }
+
+    public static double? TryParseDepthMeters(string raw)
+    {
+        raw = raw.Trim();
+        if (raw.Length == 0 || raw.Contains("- -"))
+            return null;
+
+        // Metric: "X.Yym" e.g. "1.23m"
+        if (raw.EndsWith("m", StringComparison.OrdinalIgnoreCase))
+        {
+            var s = raw[..^1].Trim();
+            if (double.TryParse(s, NumberStyles.Float, CultureInfo.InvariantCulture, out var meters))
+                return meters;
+            return null;
+        }
+
+        // Imperial: feet' inches"  e.g. "3' 7"" or "3' 7'"
+        if (raw.Contains('\''))
+        {
+            var parts = raw.Split('\'', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
+            if (parts.Length >= 1 &&
+                double.TryParse(parts[0], NumberStyles.Float, CultureInfo.InvariantCulture, out var feet))
+            {
+                double inches = 0;
+                if (parts.Length >= 2)
+                {
+                    var inchStr = parts[1].TrimEnd('"');
+                    double.TryParse(inchStr, NumberStyles.Float, CultureInfo.InvariantCulture, out inches);
+                }
+                return (feet + inches / 12.0) * 0.3048;
+            }
+        }
+
+        return null;
+    }
+
+    /// <summary>
+    /// Parses a 21-field PBDL schema 1 packet. Returns null if the line does not look like a data packet.
+    /// </summary>
+    public static UmLogPacket? TryParse(string line)
+    {
+        var fields = line.Trim().Split(',');
+        if (fields.Length < FieldCount)
+            return null;
+
+        // First field must be a small integer (Mode 0-6) to qualify as a data packet.
+        if (!int.TryParse(fields[0], out var mode) || mode is < 0 or > 6)
+            return null;
+
+        try
+        {
+            return new UmLogPacket
+            {
+                Mode = (UmMode)mode,
+                Frequency = ParseInt(fields[1]),
+                FreqType = (UmFreqType)ParseInt(fields[2]),
+                Signal = ParseInt(fields[3]),
+                GainDb = ParseInt(fields[4]),
+                DepthRaw = fields[5].Trim(),
+                CurrentRaw = fields[6].Trim(),
+                CompassAngle = ParseInt(fields[7]),
+                GuidanceArrows = ParseInt(fields[8]),
+                LdPhase = ParseInt(fields[9]),
+                Clipping = ParseInt(fields[10]) != 0,
+                DepthCurrentSetting = ParseInt(fields[11]),
+                LrArrowStyle = ParseInt(fields[12]),
+                AudioVolume = ParseInt(fields[13]),
+                AudioModulation = ParseInt(fields[14]),
+                AudioSound = ParseInt(fields[15]),
+                BatteryVoltage = ParseDouble(fields[16]),
+                BatteryType = (UmBatteryType)ParseInt(fields[17]),
+                Backlight = ParseInt(fields[18]),
+                Utility = (UmUtility)ParseInt(fields[19]),
+                MenuInUse = ParseInt(fields[20]) != 0,
+                RawText = line.Trim(),
+            };
+        }
+        catch (FormatException)
+        {
+            return null;
+        }
+    }
+
+    private static int ParseInt(string s) => int.Parse(s.Trim(), CultureInfo.InvariantCulture);
+    private static double ParseDouble(string s) => double.Parse(s.Trim(), NumberStyles.Float, CultureInfo.InvariantCulture);
+}
--- a/FieldLogger/Platforms/Android/AndroidManifest.xml
+++ b/FieldLogger/Platforms/Android/AndroidManifest.xml
@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+	<application android:allowBackup="true" android:icon="@mipmap/appicon" android:roundIcon="@mipmap/appicon_round" android:supportsRtl="true">
+		<!-- Google Maps API key: replace with your key from https://console.cloud.google.com (Maps SDK for Android) -->
+		<meta-data android:name="com.google.android.geo.API_KEY" android:value="YOUR_GOOGLE_MAPS_ANDROID_API_KEY" />
+	</application>
+	<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+	<uses-permission android:name="android.permission.INTERNET" />
+
+	<!-- BLE: Android 12+ (API 31) runtime permissions -->
+	<uses-permission android:name="android.permission.BLUETOOTH_SCAN" android:usesPermissionFlags="neverForLocation" />
+	<uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
+	<!-- BLE: Android 11 and below -->
+	<uses-permission android:name="android.permission.BLUETOOTH" android:maxSdkVersion="30" />
+	<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" android:maxSdkVersion="30" />
+	<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" android:maxSdkVersion="30" />
+	<uses-feature android:name="android.hardware.bluetooth_le" android:required="true" />
+</manifest>
--- a/FieldLogger/Platforms/Android/MainActivity.cs
+++ b/FieldLogger/Platforms/Android/MainActivity.cs
@@ -0,0 +1,10 @@
+using Android.App;
+using Android.Content.PM;
+using Android.OS;
+
+namespace FieldLogger;
+
+[Activity(Theme = "@style/Maui.SplashTheme", MainLauncher = true, LaunchMode = LaunchMode.SingleTop, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation | ConfigChanges.UiMode | ConfigChanges.ScreenLayout | ConfigChanges.SmallestScreenSize | ConfigChanges.Density)]
+public class MainActivity : MauiAppCompatActivity
+{
+}
--- a/FieldLogger/Platforms/Android/MainApplication.cs
+++ b/FieldLogger/Platforms/Android/MainApplication.cs
@@ -0,0 +1,15 @@
+using Android.App;
+using Android.Runtime;
+
+namespace FieldLogger;
+
+[Application]
+public class MainApplication : MauiApplication
+{
+	public MainApplication(IntPtr handle, JniHandleOwnership ownership)
+		: base(handle, ownership)
+	{
+	}
+
+	protected override MauiApp CreateMauiApp() => MauiProgram.CreateMauiApp();
+}
--- a/FieldLogger/Platforms/Android/Resources/values/colors.xml
+++ b/FieldLogger/Platforms/Android/Resources/values/colors.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="colorPrimary">#512BD4</color>
+    <color name="colorPrimaryDark">#2B0B98</color>
+    <color name="colorAccent">#2B0B98</color>
+</resources>
--- a/FieldLogger/Platforms/MacCatalyst/AppDelegate.cs
+++ b/FieldLogger/Platforms/MacCatalyst/AppDelegate.cs
@@ -0,0 +1,9 @@
+using Foundation;
+
+namespace FieldLogger;
+
+[Register("AppDelegate")]
+public class AppDelegate : MauiUIApplicationDelegate
+{
+	protected override MauiApp CreateMauiApp() => MauiProgram.CreateMauiApp();
+}
--- a/FieldLogger/Platforms/MacCatalyst/Entitlements.plist
+++ b/FieldLogger/Platforms/MacCatalyst/Entitlements.plist
@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+    <!-- See https://aka.ms/maui-publish-app-store#add-entitlements for more information about adding entitlements.-->
+    <dict>
+        <!-- App Sandbox must be enabled to distribute a MacCatalyst app through the Mac App Store. -->
+        <key>com.apple.security.app-sandbox</key>
+        <true/>
+        <!-- When App Sandbox is enabled, this value is required to open outgoing network connections. -->
+        <key>com.apple.security.network.client</key>
+        <true/>
+        <!-- Required for CoreBluetooth access to the UM receiver and Maglink RTK devices. -->
+        <key>com.apple.security.device.bluetooth</key>
+        <true/>
+    </dict>
+</plist>
+
--- a/FieldLogger/Platforms/MacCatalyst/Info.plist
+++ b/FieldLogger/Platforms/MacCatalyst/Info.plist
@@ -0,0 +1,42 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+    <!-- The Mac App Store requires you specify if the app uses encryption. -->
+    <!-- Please consult https://developer.apple.com/documentation/bundleresources/information_property_list/itsappusesnonexemptencryption -->
+    <!-- <key>ITSAppUsesNonExemptEncryption</key> -->
+    <!-- Please indicate <true/> or <false/> here. -->
+
+    <!-- Specify the category for your app here. -->
+    <!-- Please consult https://developer.apple.com/documentation/bundleresources/information_property_list/lsapplicationcategorytype -->
+    <!-- <key>LSApplicationCategoryType</key> -->
+    <!-- <string>public.app-category.YOUR-CATEGORY-HERE</string> -->
+	<key>UIDeviceFamily</key>
+	<array>
+		<integer>2</integer>
+	</array>
+	<key>UIRequiredDeviceCapabilities</key>
+	<array>
+		<string>arm64</string>
+	</array>
+	<key>UISupportedInterfaceOrientations</key>
+	<array>
+		<string>UIInterfaceOrientationPortrait</string>
+		<string>UIInterfaceOrientationLandscapeLeft</string>
+		<string>UIInterfaceOrientationLandscapeRight</string>
+	</array>
+	<key>UISupportedInterfaceOrientations~ipad</key>
+	<array>
+		<string>UIInterfaceOrientationPortrait</string>
+		<string>UIInterfaceOrientationPortraitUpsideDown</string>
+		<string>UIInterfaceOrientationLandscapeLeft</string>
+		<string>UIInterfaceOrientationLandscapeRight</string>
+	</array>
+	<key>XSAppIconAssets</key>
+	<string>Assets.xcassets/appicon.appiconset</string>
+	<key>NSBluetoothAlwaysUsageDescription</key>
+	<string>Field Logger uses Bluetooth to connect to your Underground Magnetics locating receiver and Maglink RTK GPS receiver.</string>
+	<key>NSLocationWhenInUseUsageDescription</key>
+	<string>Field Logger uses your location to display logged points on the map.</string>
+</dict>
+</plist>
--- a/FieldLogger/Platforms/MacCatalyst/Program.cs
+++ b/FieldLogger/Platforms/MacCatalyst/Program.cs
@@ -0,0 +1,15 @@
+using ObjCRuntime;
+using UIKit;
+
+namespace FieldLogger;
+
+public class Program
+{
+	// This is the main entry point of the application.
+	static void Main(string[] args)
+	{
+		// if you want to use a different Application Delegate class from "AppDelegate"
+		// you can specify it here.
+		UIApplication.Main(args, null, typeof(AppDelegate));
+	}
+}
--- a/FieldLogger/Platforms/Tizen/Main.cs
+++ b/FieldLogger/Platforms/Tizen/Main.cs
@@ -0,0 +1,16 @@
+using System;
+using Microsoft.Maui;
+using Microsoft.Maui.Hosting;
+
+namespace FieldLogger;
+
+class Program : MauiApplication
+{
+	protected override MauiApp CreateMauiApp() => MauiProgram.CreateMauiApp();
+
+	static void Main(string[] args)
+	{
+		var app = new Program();
+		app.Run(args);
+	}
+}
--- a/FieldLogger/Platforms/Tizen/tizen-manifest.xml
+++ b/FieldLogger/Platforms/Tizen/tizen-manifest.xml
@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest package="maui-application-id-placeholder" version="0.0.0" api-version="9" xmlns="http://tizen.org/ns/packages">
+  <profile name="common" />
+  <ui-application appid="maui-application-id-placeholder" exec="FieldLogger.dll" multiple="false" nodisplay="false" taskmanage="true" type="dotnet" launch_mode="single">
+    <label>maui-application-title-placeholder</label>
+    <icon>maui-appicon-placeholder</icon>
+    <metadata key="http://tizen.org/metadata/prefer_dotnet_aot" value="true" />
+  </ui-application>
+  <shortcut-list />
+  <privileges>
+    <privilege>http://tizen.org/privilege/internet</privilege>
+  </privileges> 
+  <dependencies />
+  <provides-appdefined-privileges />
+</manifest>
--- a/FieldLogger/Platforms/Windows/App.xaml
+++ b/FieldLogger/Platforms/Windows/App.xaml
@@ -0,0 +1,8 @@
+<maui:MauiWinUIApplication
+    x:Class="FieldLogger.WinUI.App"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:maui="using:Microsoft.Maui"
+    xmlns:local="using:FieldLogger.WinUI">
+
+</maui:MauiWinUIApplication>
--- a/FieldLogger/Platforms/Windows/App.xaml.cs
+++ b/FieldLogger/Platforms/Windows/App.xaml.cs
@@ -0,0 +1,24 @@
+using Microsoft.UI.Xaml;
+
+// To learn more about WinUI, the WinUI project structure,
+// and more about our project templates, see: http://aka.ms/winui-project-info.
+
+namespace FieldLogger.WinUI;
+
+/// <summary>
+/// Provides application-specific behavior to supplement the default Application class.
+/// </summary>
+public partial class App : MauiWinUIApplication
+{
+	/// <summary>
+	/// Initializes the singleton application object.  This is the first line of authored code
+	/// executed, and as such is the logical equivalent of main() or WinMain().
+	/// </summary>
+	public App()
+	{
+		this.InitializeComponent();
+	}
+
+	protected override MauiApp CreateMauiApp() => MauiProgram.CreateMauiApp();
+}
+
--- a/FieldLogger/Platforms/Windows/Package.appxmanifest
+++ b/FieldLogger/Platforms/Windows/Package.appxmanifest
@@ -0,0 +1,47 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Package
+  xmlns="http://schemas.microsoft.com/appx/manifest/foundation/windows10"
+  xmlns:uap="http://schemas.microsoft.com/appx/manifest/uap/windows10"
+  xmlns:mp="http://schemas.microsoft.com/appx/2014/phone/manifest"
+  xmlns:rescap="http://schemas.microsoft.com/appx/manifest/foundation/windows10/restrictedcapabilities"
+  IgnorableNamespaces="uap rescap">
+
+  <Identity Name="maui-package-name-placeholder" Publisher="CN=User Name" Version="0.0.0.0" />
+
+  <mp:PhoneIdentity PhoneProductId="0E66E150-3452-4D9B-BA88-43820FA51A97" PhonePublisherId="00000000-0000-0000-0000-000000000000"/>
+
+  <Properties>
+    <DisplayName>$placeholder$</DisplayName>
+    <PublisherDisplayName>User Name</PublisherDisplayName>
+    <Logo>$placeholder$.png</Logo>
+  </Properties>
+
+  <Dependencies>
+    <TargetDeviceFamily Name="Windows.Universal" MinVersion="10.0.17763.0" MaxVersionTested="10.0.19041.0" />
+    <TargetDeviceFamily Name="Windows.Desktop" MinVersion="10.0.17763.0" MaxVersionTested="10.0.19041.0" />
+  </Dependencies>
+
+  <Resources>
+    <Resource Language="x-generate" />
+  </Resources>
+
+  <Applications>
+    <Application Id="App" Executable="$targetnametoken$.exe" EntryPoint="$targetentrypoint$">
+      <uap:VisualElements
+        DisplayName="$placeholder$"
+        Description="$placeholder$"
+        Square150x150Logo="$placeholder$.png"
+        Square44x44Logo="$placeholder$.png"
+        BackgroundColor="transparent">
+        <uap:DefaultTile Square71x71Logo="$placeholder$.png" Wide310x150Logo="$placeholder$.png" Square310x310Logo="$placeholder$.png" />
+        <uap:SplashScreen Image="$placeholder$.png" />
+      </uap:VisualElements>
+    </Application>
+  </Applications>
+
+  <Capabilities>
+    <rescap:Capability Name="runFullTrust" />
+    <DeviceCapability Name="bluetooth" />
+  </Capabilities>
+
+</Package>
--- a/FieldLogger/Platforms/Windows/app.manifest
+++ b/FieldLogger/Platforms/Windows/app.manifest
@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<assembly manifestVersion="1.0" xmlns="urn:schemas-microsoft-com:asm.v1">
+  <assemblyIdentity version="1.0.0.0" name="FieldLogger.WinUI.app"/>
+
+  <application xmlns="urn:schemas-microsoft-com:asm.v3">
+    <windowsSettings>
+      <!-- The combination of below two tags have the following effect:
+           1) Per-Monitor for >= Windows 10 Anniversary Update
+           2) System < Windows 10 Anniversary Update
+      -->
+      <dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">true/PM</dpiAware>
+      <dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">PerMonitorV2, PerMonitor</dpiAwareness>
+    </windowsSettings>
+  </application>
+</assembly>
--- a/FieldLogger/Platforms/iOS/AppDelegate.cs
+++ b/FieldLogger/Platforms/iOS/AppDelegate.cs
@@ -0,0 +1,9 @@
+using Foundation;
+
+namespace FieldLogger;
+
+[Register("AppDelegate")]
+public class AppDelegate : MauiUIApplicationDelegate
+{
+	protected override MauiApp CreateMauiApp() => MauiProgram.CreateMauiApp();
+}
--- a/FieldLogger/Platforms/iOS/Info.plist
+++ b/FieldLogger/Platforms/iOS/Info.plist
@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>LSRequiresIPhoneOS</key>
+	<true/>
+	<key>UIDeviceFamily</key>
+	<array>
+		<integer>1</integer>
+		<integer>2</integer>
+	</array>
+	<key>UIRequiredDeviceCapabilities</key>
+	<array>
+		<string>arm64</string>
+	</array>
+	<key>UISupportedInterfaceOrientations</key>
+	<array>
+		<string>UIInterfaceOrientationPortrait</string>
+		<string>UIInterfaceOrientationLandscapeLeft</string>
+		<string>UIInterfaceOrientationLandscapeRight</string>
+	</array>
+	<key>UISupportedInterfaceOrientations~ipad</key>
+	<array>
+		<string>UIInterfaceOrientationPortrait</string>
+		<string>UIInterfaceOrientationPortraitUpsideDown</string>
+		<string>UIInterfaceOrientationLandscapeLeft</string>
+		<string>UIInterfaceOrientationLandscapeRight</string>
+	</array>
+	<key>XSAppIconAssets</key>
+	<string>Assets.xcassets/appicon.appiconset</string>
+	<key>NSBluetoothAlwaysUsageDescription</key>
+	<string>Field Logger uses Bluetooth to connect to your Underground Magnetics locating receiver and Maglink RTK GPS receiver.</string>
+	<key>NSLocationWhenInUseUsageDescription</key>
+	<string>Field Logger uses your location to display logged points on the map.</string>
+</dict>
+</plist>
--- a/FieldLogger/Platforms/iOS/Program.cs
+++ b/FieldLogger/Platforms/iOS/Program.cs
@@ -0,0 +1,15 @@
+using ObjCRuntime;
+using UIKit;
+
+namespace FieldLogger;
+
+public class Program
+{
+	// This is the main entry point of the application.
+	static void Main(string[] args)
+	{
+		// if you want to use a different Application Delegate class from "AppDelegate"
+		// you can specify it here.
+		UIApplication.Main(args, null, typeof(AppDelegate));
+	}
+}
--- a/FieldLogger/Platforms/iOS/Resources/PrivacyInfo.xcprivacy
+++ b/FieldLogger/Platforms/iOS/Resources/PrivacyInfo.xcprivacy
@@ -0,0 +1,51 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+This is the minimum required version of the Apple Privacy Manifest for .NET MAUI apps.
+The contents below are needed because of APIs that are used in the .NET framework and .NET MAUI SDK.
+
+You are responsible for adding extra entries as needed for your application.
+
+More information: https://aka.ms/maui-privacy-manifest
+-->
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+    <key>NSPrivacyAccessedAPITypes</key>
+    <array>
+        <dict>
+            <key>NSPrivacyAccessedAPIType</key>
+            <string>NSPrivacyAccessedAPICategoryFileTimestamp</string>
+            <key>NSPrivacyAccessedAPITypeReasons</key>
+            <array>
+                <string>C617.1</string>
+            </array>
+        </dict>
+        <dict>
+            <key>NSPrivacyAccessedAPIType</key>
+            <string>NSPrivacyAccessedAPICategorySystemBootTime</string>
+            <key>NSPrivacyAccessedAPITypeReasons</key>
+            <array>
+                <string>35F9.1</string>
+            </array>
+        </dict>
+        <dict>
+            <key>NSPrivacyAccessedAPIType</key>
+            <string>NSPrivacyAccessedAPICategoryDiskSpace</string>
+            <key>NSPrivacyAccessedAPITypeReasons</key>
+            <array>
+                <string>E174.1</string>
+            </array>
+        </dict>
+        <!--
+            The entry below is only needed when you're using the Preferences API in your app.
+        <dict>
+            <key>NSPrivacyAccessedAPIType</key>
+            <string>NSPrivacyAccessedAPICategoryUserDefaults</string>
+            <key>NSPrivacyAccessedAPITypeReasons</key>
+            <array>
+                <string>CA92.1</string>
+            </array>
+        </dict> -->
+    </array>
+</dict>
+</plist>
--- a/FieldLogger/Properties/launchSettings.json
+++ b/FieldLogger/Properties/launchSettings.json
@@ -0,0 +1,8 @@
+{
+  "profiles": {
+    "Windows Machine": {
+      "commandName": "Project",
+      "nativeDebugging": false
+    }
+  }
+}
--- a/FieldLogger/Resources/AppIcon/appicon.svg
+++ b/FieldLogger/Resources/AppIcon/appicon.svg
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg width="456" height="456" viewBox="0 0 456 456" version="1.1" xmlns="http://www.w3.org/2000/svg">
+    <rect x="0" y="0" width="456" height="456" fill="#512BD4" />
+</svg>
--- a/FieldLogger/Resources/AppIcon/appiconfg.svg
+++ b/FieldLogger/Resources/AppIcon/appiconfg.svg
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<svg width="456" height="456" viewBox="0 0 456 456" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" xml:space="preserve" xmlns:serif="http://www.serif.com/" style="fill-rule:evenodd;clip-rule:evenodd;stroke-linejoin:round;stroke-miterlimit:2;">
+    <path d="m 105.50037,281.60863 c -2.70293,0 -5.00091,-0.90042 -6.893127,-2.70209 -1.892214,-1.84778 -2.837901,-4.04181 -2.837901,-6.58209 0,-2.58722 0.945687,-4.80389 2.837901,-6.65167 1.892217,-1.84778 4.190197,-2.77167 6.893127,-2.77167 2.74819,0 5.06798,0.92389 6.96019,2.77167 1.93749,1.84778 2.90581,4.06445 2.90581,6.65167 0,2.54028 -0.96832,4.73431 -2.90581,6.58209 -1.89221,1.80167 -4.212,2.70209 -6.96019,2.70209 z" style="fill:#ffffff;fill-rule:nonzero;stroke-width:0.838376" />
+    <path d="M 213.56111,280.08446 H 195.99044 L 149.69953,207.0544 c -1.17121,-1.84778 -2.14037,-3.76515 -2.90581,-5.75126 h -0.40578 c 0.36051,2.12528 0.54076,6.67515 0.54076,13.6496 v 65.13172 h -15.54349 v -99.36009 h 18.71925 l 44.7374,71.29798 c 1.89222,2.95695 3.1087,4.98917 3.64945,6.09751 h 0.26996 c -0.45021,-2.6325 -0.67573,-7.09015 -0.67573,-13.37293 v -64.02256 h 15.47557 z" style="fill:#ffffff;fill-rule:nonzero;stroke-width:0.838376" />
+    <path d="m 289.25134,280.08446 h -54.40052 v -99.36009 h 52.23835 v 13.99669 h -36.15411 v 28.13085 h 33.31621 v 13.9271 h -33.31621 v 29.37835 h 38.31628 z" style="fill:#ffffff;fill-rule:nonzero;stroke-width:0.838376" />
+    <path d="M 366.56466,194.72106 H 338.7222 v 85.3634 h -16.08423 v -85.3634 h -27.77455 v -13.99669 h 71.70124 z" style="fill:#ffffff;fill-rule:nonzero;stroke-width:0.838376" />
+</svg>
--- a/FieldLogger/Resources/Fonts/OpenSans-Regular.ttf
+++ b/FieldLogger/Resources/Fonts/OpenSans-Regular.ttf
--- a/FieldLogger/Resources/Fonts/OpenSans-Semibold.ttf
+++ b/FieldLogger/Resources/Fonts/OpenSans-Semibold.ttf
--- a/FieldLogger/Resources/Images/dotnet_bot.png
+++ b/FieldLogger/Resources/Images/dotnet_bot.png
--- a/FieldLogger/Resources/Raw/AboutAssets.txt
+++ b/FieldLogger/Resources/Raw/AboutAssets.txt
@@ -0,0 +1,15 @@
+Any raw assets you want to be deployed with your application can be placed in
+this directory (and child directories). Deployment of the asset to your application
+is automatically handled by the following `MauiAsset` Build Action within your `.csproj`.
+
+	<MauiAsset Include="Resources\Raw\**" LogicalName="%(RecursiveDir)%(Filename)%(Extension)" />
+
+These files will be deployed with your package and will be accessible using Essentials:
+
+	async Task LoadMauiAsset()
+	{
+		using var stream = await FileSystem.OpenAppPackageFileAsync("AboutAssets.txt");
+		using var reader = new StreamReader(stream);
+
+		var contents = reader.ReadToEnd();
+	}
--- a/FieldLogger/Resources/Raw/map.html
+++ b/FieldLogger/Resources/Raw/map.html
@@ -0,0 +1,64 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <style>
+        html, body, #map { height: 100%; margin: 0; padding: 0; }
+    </style>
+</head>
+<body>
+    <div id="map"></div>
+    <script>
+        let map;
+        let markers = [];
+        let infoWindow;
+
+        function initMap() {
+            map = new google.maps.Map(document.getElementById('map'), {
+                center: { lat: 39.5, lng: -98.35 },
+                zoom: 4,
+                mapTypeId: 'hybrid'
+            });
+            infoWindow = new google.maps.InfoWindow();
+        }
+
+        // Called from the app with an array of point objects.
+        function setPoints(points) {
+            markers.forEach(m => m.setMap(null));
+            markers = [];
+            if (!map || !points || points.length === 0) return;
+
+            const bounds = new google.maps.LatLngBounds();
+            points.forEach(p => {
+                const pos = { lat: p.lat, lng: p.lng };
+                const marker = new google.maps.Marker({
+                    position: pos,
+                    map: map,
+                    title: '#' + p.id + ' ' + p.utility
+                });
+                marker.addListener('click', () => {
+                    infoWindow.setContent(
+                        '<b>#' + p.id + ' &middot; ' + p.utility + '</b><br/>' +
+                        'Depth: ' + p.depth + ' &middot; Current: ' + p.current + '<br/>' +
+                        'Frequency: ' + p.frequency + ' Hz<br/>' +
+                        'Fix: ' + p.fix + ' (&plusmn;' + p.hrms.toFixed(3) + ' m)<br/>' +
+                        p.time);
+                    infoWindow.open(map, marker);
+                });
+                markers.push(marker);
+                bounds.extend(pos);
+            });
+
+            if (points.length === 1) {
+                map.setCenter(bounds.getCenter());
+                map.setZoom(19);
+            } else {
+                map.fitBounds(bounds, 60);
+            }
+        }
+    </script>
+    <script async
+        src="https://maps.googleapis.com/maps/api/js?key=%%GOOGLE_MAPS_API_KEY%%&callback=initMap"></script>
+</body>
+</html>
--- a/FieldLogger/Resources/Splash/splash.svg
+++ b/FieldLogger/Resources/Splash/splash.svg
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<svg width="456" height="456" viewBox="0 0 456 456" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" xml:space="preserve" xmlns:serif="http://www.serif.com/" style="fill-rule:evenodd;clip-rule:evenodd;stroke-linejoin:round;stroke-miterlimit:2;">
+    <path d="m 105.50037,281.60863 c -2.70293,0 -5.00091,-0.90042 -6.893127,-2.70209 -1.892214,-1.84778 -2.837901,-4.04181 -2.837901,-6.58209 0,-2.58722 0.945687,-4.80389 2.837901,-6.65167 1.892217,-1.84778 4.190197,-2.77167 6.893127,-2.77167 2.74819,0 5.06798,0.92389 6.96019,2.77167 1.93749,1.84778 2.90581,4.06445 2.90581,6.65167 0,2.54028 -0.96832,4.73431 -2.90581,6.58209 -1.89221,1.80167 -4.212,2.70209 -6.96019,2.70209 z" style="fill:#ffffff;fill-rule:nonzero;stroke-width:0.838376" />
+    <path d="M 213.56111,280.08446 H 195.99044 L 149.69953,207.0544 c -1.17121,-1.84778 -2.14037,-3.76515 -2.90581,-5.75126 h -0.40578 c 0.36051,2.12528 0.54076,6.67515 0.54076,13.6496 v 65.13172 h -15.54349 v -99.36009 h 18.71925 l 44.7374,71.29798 c 1.89222,2.95695 3.1087,4.98917 3.64945,6.09751 h 0.26996 c -0.45021,-2.6325 -0.67573,-7.09015 -0.67573,-13.37293 v -64.02256 h 15.47557 z" style="fill:#ffffff;fill-rule:nonzero;stroke-width:0.838376" />
+    <path d="m 289.25134,280.08446 h -54.40052 v -99.36009 h 52.23835 v 13.99669 h -36.15411 v 28.13085 h 33.31621 v 13.9271 h -33.31621 v 29.37835 h 38.31628 z" style="fill:#ffffff;fill-rule:nonzero;stroke-width:0.838376" />
+    <path d="M 366.56466,194.72106 H 338.7222 v 85.3634 h -16.08423 v -85.3634 h -27.77455 v -13.99669 h 71.70124 z" style="fill:#ffffff;fill-rule:nonzero;stroke-width:0.838376" />
+</svg>
--- a/FieldLogger/Resources/Styles/Colors.xaml
+++ b/FieldLogger/Resources/Styles/Colors.xaml
@@ -0,0 +1,45 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<?xaml-comp compile="true" ?>
+<ResourceDictionary 
+    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml">
+
+    <!-- Note: For Android please see also Platforms\Android\Resources\values\colors.xml -->
+
+    <Color x:Key="Primary">#512BD4</Color>
+    <Color x:Key="PrimaryDark">#ac99ea</Color>
+    <Color x:Key="PrimaryDarkText">#242424</Color>
+    <Color x:Key="Secondary">#DFD8F7</Color>
+    <Color x:Key="SecondaryDarkText">#9880e5</Color>
+    <Color x:Key="Tertiary">#2B0B98</Color>
+
+    <Color x:Key="White">White</Color>
+    <Color x:Key="Black">Black</Color>
+    <Color x:Key="Magenta">#D600AA</Color>
+    <Color x:Key="MidnightBlue">#190649</Color>
+    <Color x:Key="OffBlack">#1f1f1f</Color>
+
+    <Color x:Key="Gray100">#E1E1E1</Color>
+    <Color x:Key="Gray200">#C8C8C8</Color>
+    <Color x:Key="Gray300">#ACACAC</Color>
+    <Color x:Key="Gray400">#919191</Color>
+    <Color x:Key="Gray500">#6E6E6E</Color>
+    <Color x:Key="Gray600">#404040</Color>
+    <Color x:Key="Gray900">#212121</Color>
+    <Color x:Key="Gray950">#141414</Color>
+
+    <SolidColorBrush x:Key="PrimaryBrush" Color="{StaticResource Primary}"/>
+    <SolidColorBrush x:Key="SecondaryBrush" Color="{StaticResource Secondary}"/>
+    <SolidColorBrush x:Key="TertiaryBrush" Color="{StaticResource Tertiary}"/>
+    <SolidColorBrush x:Key="WhiteBrush" Color="{StaticResource White}"/>
+    <SolidColorBrush x:Key="BlackBrush" Color="{StaticResource Black}"/>
+
+    <SolidColorBrush x:Key="Gray100Brush" Color="{StaticResource Gray100}"/>
+    <SolidColorBrush x:Key="Gray200Brush" Color="{StaticResource Gray200}"/>
+    <SolidColorBrush x:Key="Gray300Brush" Color="{StaticResource Gray300}"/>
+    <SolidColorBrush x:Key="Gray400Brush" Color="{StaticResource Gray400}"/>
+    <SolidColorBrush x:Key="Gray500Brush" Color="{StaticResource Gray500}"/>
+    <SolidColorBrush x:Key="Gray600Brush" Color="{StaticResource Gray600}"/>
+    <SolidColorBrush x:Key="Gray900Brush" Color="{StaticResource Gray900}"/>
+    <SolidColorBrush x:Key="Gray950Brush" Color="{StaticResource Gray950}"/>
+</ResourceDictionary>
--- a/FieldLogger/Resources/Styles/Styles.xaml
+++ b/FieldLogger/Resources/Styles/Styles.xaml
@@ -0,0 +1,444 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<?xaml-comp compile="true" ?>
+<ResourceDictionary 
+    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml">
+
+    <Style TargetType="ActivityIndicator">
+        <Setter Property="Color" Value="{AppThemeBinding Light={StaticResource Primary}, Dark={StaticResource White}}" />
+    </Style>
+
+    <Style TargetType="IndicatorView">
+        <Setter Property="IndicatorColor" Value="{AppThemeBinding Light={StaticResource Gray200}, Dark={StaticResource Gray500}}"/>
+        <Setter Property="SelectedIndicatorColor" Value="{AppThemeBinding Light={StaticResource Gray950}, Dark={StaticResource Gray100}}"/>
+    </Style>
+
+    <Style TargetType="Border">
+        <Setter Property="Stroke" Value="{AppThemeBinding Light={StaticResource Gray200}, Dark={StaticResource Gray500}}" />
+        <Setter Property="StrokeShape" Value="Rectangle"/>
+        <Setter Property="StrokeThickness" Value="1"/>
+    </Style>
+
+    <Style TargetType="BoxView">
+        <Setter Property="BackgroundColor" Value="{AppThemeBinding Light={StaticResource Gray950}, Dark={StaticResource Gray200}}" />
+    </Style>
+
+    <Style TargetType="Button">
+        <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource White}, Dark={StaticResource PrimaryDarkText}}" />
+        <Setter Property="BackgroundColor" Value="{AppThemeBinding Light={StaticResource Primary}, Dark={StaticResource PrimaryDark}}" />
+        <Setter Property="FontFamily" Value="OpenSansRegular"/>
+        <Setter Property="FontSize" Value="14"/>
+        <Setter Property="BorderWidth" Value="0"/>
+        <Setter Property="CornerRadius" Value="8"/>
+        <Setter Property="Padding" Value="14,10"/>
+        <Setter Property="MinimumHeightRequest" Value="44"/>
+        <Setter Property="MinimumWidthRequest" Value="44"/>
+        <Setter Property="VisualStateManager.VisualStateGroups">
+            <VisualStateGroupList>
+                <VisualStateGroup x:Name="CommonStates">
+                    <VisualState x:Name="Normal" />
+                    <VisualState x:Name="Disabled">
+                        <VisualState.Setters>
+                            <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource Gray950}, Dark={StaticResource Gray200}}" />
+                            <Setter Property="BackgroundColor" Value="{AppThemeBinding Light={StaticResource Gray200}, Dark={StaticResource Gray600}}" />
+                        </VisualState.Setters>
+                    </VisualState>
+                    <VisualState x:Name="PointerOver" />
+                </VisualStateGroup>
+            </VisualStateGroupList>
+        </Setter>
+    </Style>
+
+    <Style TargetType="CheckBox">
+        <Setter Property="Color" Value="{AppThemeBinding Light={StaticResource Primary}, Dark={StaticResource White}}" />
+        <Setter Property="MinimumHeightRequest" Value="44"/>
+        <Setter Property="MinimumWidthRequest" Value="44"/>
+        <Setter Property="VisualStateManager.VisualStateGroups">
+            <VisualStateGroupList>
+                <VisualStateGroup x:Name="CommonStates">
+                    <VisualState x:Name="Normal" />
+                    <VisualState x:Name="Disabled">
+                        <VisualState.Setters>
+                            <Setter Property="Color" Value="{AppThemeBinding Light={StaticResource Gray300}, Dark={StaticResource Gray600}}" />
+                        </VisualState.Setters>
+                    </VisualState>
+                </VisualStateGroup>
+            </VisualStateGroupList>
+        </Setter>
+    </Style>
+
+    <Style TargetType="DatePicker">
+        <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource Gray900}, Dark={StaticResource White}}" />
+        <Setter Property="BackgroundColor" Value="Transparent" />
+        <Setter Property="FontFamily" Value="OpenSansRegular"/>
+        <Setter Property="FontSize" Value="14"/>
+        <Setter Property="MinimumHeightRequest" Value="44"/>
+        <Setter Property="MinimumWidthRequest" Value="44"/>
+        <Setter Property="VisualStateManager.VisualStateGroups">
+            <VisualStateGroupList>
+                <VisualStateGroup x:Name="CommonStates">
+                    <VisualState x:Name="Normal" />
+                    <VisualState x:Name="Disabled">
+                        <VisualState.Setters>
+                            <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource Gray200}, Dark={StaticResource Gray500}}" />
+                        </VisualState.Setters>
+                    </VisualState>
+                </VisualStateGroup>
+            </VisualStateGroupList>
+        </Setter>
+    </Style>
+
+    <Style TargetType="Editor">
+        <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource Black}, Dark={StaticResource White}}" />
+        <Setter Property="BackgroundColor" Value="Transparent" />
+        <Setter Property="FontFamily" Value="OpenSansRegular"/>
+        <Setter Property="FontSize" Value="14" />
+        <Setter Property="PlaceholderColor" Value="{AppThemeBinding Light={StaticResource Gray200}, Dark={StaticResource Gray500}}" />
+        <Setter Property="MinimumHeightRequest" Value="44"/>
+        <Setter Property="MinimumWidthRequest" Value="44"/>
+        <Setter Property="VisualStateManager.VisualStateGroups">
+            <VisualStateGroupList>
+                <VisualStateGroup x:Name="CommonStates">
+                    <VisualState x:Name="Normal" />
+                    <VisualState x:Name="Disabled">
+                        <VisualState.Setters>
+                            <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource Gray300}, Dark={StaticResource Gray600}}" />
+                        </VisualState.Setters>
+                    </VisualState>
+                </VisualStateGroup>
+            </VisualStateGroupList>
+        </Setter>
+    </Style>
+
+    <Style TargetType="Entry">
+        <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource Black}, Dark={StaticResource White}}" />
+        <Setter Property="BackgroundColor" Value="Transparent" />
+        <Setter Property="FontFamily" Value="OpenSansRegular"/>
+        <Setter Property="FontSize" Value="14" />
+        <Setter Property="PlaceholderColor" Value="{AppThemeBinding Light={StaticResource Gray200}, Dark={StaticResource Gray500}}" />
+        <Setter Property="MinimumHeightRequest" Value="44"/>
+        <Setter Property="MinimumWidthRequest" Value="44"/>
+        <Setter Property="VisualStateManager.VisualStateGroups">
+            <VisualStateGroupList>
+                <VisualStateGroup x:Name="CommonStates">
+                    <VisualState x:Name="Normal" />
+                    <VisualState x:Name="Disabled">
+                        <VisualState.Setters>
+                            <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource Gray300}, Dark={StaticResource Gray600}}" />
+                        </VisualState.Setters>
+                    </VisualState>
+                </VisualStateGroup>
+            </VisualStateGroupList>
+        </Setter>
+    </Style>
+
+    <Style TargetType="ImageButton">
+        <Setter Property="Opacity" Value="1" />
+        <Setter Property="BorderColor" Value="Transparent"/>
+        <Setter Property="BorderWidth" Value="0"/>
+        <Setter Property="CornerRadius" Value="0"/>
+        <Setter Property="MinimumHeightRequest" Value="44"/>
+        <Setter Property="MinimumWidthRequest" Value="44"/>
+        <Setter Property="VisualStateManager.VisualStateGroups">
+            <VisualStateGroupList>
+                <VisualStateGroup x:Name="CommonStates">
+                    <VisualState x:Name="Normal" />
+                    <VisualState x:Name="Disabled">
+                        <VisualState.Setters>
+                            <Setter Property="Opacity" Value="0.5" />
+                        </VisualState.Setters>
+                    </VisualState>
+                    <VisualState x:Name="PointerOver" />
+                </VisualStateGroup>
+            </VisualStateGroupList>
+        </Setter>
+    </Style>
+
+    <Style TargetType="Label">
+        <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource Black}, Dark={StaticResource White}}" />
+        <Setter Property="BackgroundColor" Value="Transparent" />
+        <Setter Property="FontFamily" Value="OpenSansRegular" />
+        <Setter Property="FontSize" Value="14" />
+        <Setter Property="VisualStateManager.VisualStateGroups">
+            <VisualStateGroupList>
+                <VisualStateGroup x:Name="CommonStates">
+                    <VisualState x:Name="Normal" />
+                    <VisualState x:Name="Disabled">
+                        <VisualState.Setters>
+                            <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource Gray300}, Dark={StaticResource Gray600}}" />
+                        </VisualState.Setters>
+                    </VisualState>
+                </VisualStateGroup>
+            </VisualStateGroupList>
+        </Setter>
+    </Style>
+
+    <Style TargetType="Span">
+        <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource Black}, Dark={StaticResource White}}" />
+    </Style>
+
+    <Style TargetType="Label" x:Key="Headline">
+        <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource MidnightBlue}, Dark={StaticResource White}}" />
+        <Setter Property="FontSize" Value="32" />
+        <Setter Property="HorizontalOptions" Value="Center" />
+        <Setter Property="HorizontalTextAlignment" Value="Center" />
+    </Style>
+
+    <Style TargetType="Label" x:Key="SubHeadline">
+        <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource MidnightBlue}, Dark={StaticResource White}}" />
+        <Setter Property="FontSize" Value="24" />
+        <Setter Property="HorizontalOptions" Value="Center" />
+        <Setter Property="HorizontalTextAlignment" Value="Center" />
+    </Style>
+
+    <Style TargetType="ListView">
+        <Setter Property="SeparatorColor" Value="{AppThemeBinding Light={StaticResource Gray200}, Dark={StaticResource Gray500}}" />
+        <Setter Property="RefreshControlColor" Value="{AppThemeBinding Light={StaticResource Gray900}, Dark={StaticResource Gray200}}" />
+    </Style>
+
+    <Style TargetType="Picker">
+        <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource Gray900}, Dark={StaticResource White}}" />
+        <Setter Property="TitleColor" Value="{AppThemeBinding Light={StaticResource Gray900}, Dark={StaticResource Gray200}}" />
+        <Setter Property="BackgroundColor" Value="Transparent" />
+        <Setter Property="FontFamily" Value="OpenSansRegular"/>
+        <Setter Property="FontSize" Value="14" />
+        <Setter Property="MinimumHeightRequest" Value="44"/>
+        <Setter Property="MinimumWidthRequest" Value="44"/>
+        <Setter Property="VisualStateManager.VisualStateGroups">
+            <VisualStateGroupList>
+                <VisualStateGroup x:Name="CommonStates">
+                    <VisualState x:Name="Normal" />
+                    <VisualState x:Name="Disabled">
+                        <VisualState.Setters>
+                            <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource Gray300}, Dark={StaticResource Gray600}}" />
+                            <Setter Property="TitleColor" Value="{AppThemeBinding Light={StaticResource Gray300}, Dark={StaticResource Gray600}}" />
+                        </VisualState.Setters>
+                    </VisualState>
+                </VisualStateGroup>
+            </VisualStateGroupList>
+        </Setter>
+    </Style>
+
+    <Style TargetType="ProgressBar">
+        <Setter Property="ProgressColor" Value="{AppThemeBinding Light={StaticResource Primary}, Dark={StaticResource White}}" />
+        <Setter Property="VisualStateManager.VisualStateGroups">
+            <VisualStateGroupList>
+                <VisualStateGroup x:Name="CommonStates">
+                    <VisualState x:Name="Normal" />
+                    <VisualState x:Name="Disabled">
+                        <VisualState.Setters>
+                            <Setter Property="ProgressColor" Value="{AppThemeBinding Light={StaticResource Gray300}, Dark={StaticResource Gray600}}" />
+                        </VisualState.Setters>
+                    </VisualState>
+                </VisualStateGroup>
+            </VisualStateGroupList>
+        </Setter>
+    </Style>
+
+    <Style TargetType="RadioButton">
+        <Setter Property="BackgroundColor" Value="Transparent"/>
+        <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource Black}, Dark={StaticResource White}}" />
+        <Setter Property="FontFamily" Value="OpenSansRegular"/>
+        <Setter Property="FontSize" Value="14"/>
+        <Setter Property="MinimumHeightRequest" Value="44"/>
+        <Setter Property="MinimumWidthRequest" Value="44"/>
+        <Setter Property="VisualStateManager.VisualStateGroups">
+            <VisualStateGroupList>
+                <VisualStateGroup x:Name="CommonStates">
+                    <VisualState x:Name="Normal" />
+                    <VisualState x:Name="Disabled">
+                        <VisualState.Setters>
+                            <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource Gray300}, Dark={StaticResource Gray600}}" />
+                        </VisualState.Setters>
+                    </VisualState>
+                </VisualStateGroup>
+            </VisualStateGroupList>
+        </Setter>
+    </Style>
+
+    <Style TargetType="RefreshView">
+        <Setter Property="RefreshColor" Value="{AppThemeBinding Light={StaticResource Gray900}, Dark={StaticResource Gray200}}" />
+    </Style>
+
+    <Style TargetType="SearchBar">
+        <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource Gray900}, Dark={StaticResource White}}" />
+        <Setter Property="PlaceholderColor" Value="{StaticResource Gray500}" />
+        <Setter Property="CancelButtonColor" Value="{StaticResource Gray500}" />
+        <Setter Property="BackgroundColor" Value="Transparent" />
+        <Setter Property="FontFamily" Value="OpenSansRegular" />
+        <Setter Property="FontSize" Value="14" />
+        <Setter Property="MinimumHeightRequest" Value="44"/>
+        <Setter Property="MinimumWidthRequest" Value="44"/>
+        <Setter Property="VisualStateManager.VisualStateGroups">
+            <VisualStateGroupList>
+                <VisualStateGroup x:Name="CommonStates">
+                    <VisualState x:Name="Normal" />
+                    <VisualState x:Name="Disabled">
+                        <VisualState.Setters>
+                            <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource Gray300}, Dark={StaticResource Gray600}}" />
+                            <Setter Property="PlaceholderColor" Value="{AppThemeBinding Light={StaticResource Gray300}, Dark={StaticResource Gray600}}" />
+                        </VisualState.Setters>
+                    </VisualState>
+                </VisualStateGroup>
+            </VisualStateGroupList>
+        </Setter>
+    </Style>
+
+    <Style TargetType="SearchHandler">
+        <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource Gray900}, Dark={StaticResource White}}" />
+        <Setter Property="PlaceholderColor" Value="{StaticResource Gray500}" />
+        <Setter Property="BackgroundColor" Value="Transparent" />
+        <Setter Property="FontFamily" Value="OpenSansRegular" />
+        <Setter Property="FontSize" Value="14" />
+        <Setter Property="VisualStateManager.VisualStateGroups">
+            <VisualStateGroupList>
+                <VisualStateGroup x:Name="CommonStates">
+                    <VisualState x:Name="Normal" />
+                    <VisualState x:Name="Disabled">
+                        <VisualState.Setters>
+                            <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource Gray300}, Dark={StaticResource Gray600}}" />
+                            <Setter Property="PlaceholderColor" Value="{AppThemeBinding Light={StaticResource Gray300}, Dark={StaticResource Gray600}}" />
+                        </VisualState.Setters>
+                    </VisualState>
+                </VisualStateGroup>
+            </VisualStateGroupList>
+        </Setter>
+    </Style>
+
+    <Style TargetType="Shadow">
+        <Setter Property="Radius" Value="15" />
+        <Setter Property="Opacity" Value="0.5" />
+        <Setter Property="Brush" Value="{AppThemeBinding Light={StaticResource White}, Dark={StaticResource White}}" />
+        <Setter Property="Offset" Value="10,10" />
+    </Style>
+
+    <Style TargetType="Slider">
+        <Setter Property="MinimumTrackColor" Value="{AppThemeBinding Light={StaticResource Primary}, Dark={StaticResource White}}" />
+        <Setter Property="MaximumTrackColor" Value="{AppThemeBinding Light={StaticResource Gray200}, Dark={StaticResource Gray600}}" />
+        <Setter Property="ThumbColor" Value="{AppThemeBinding Light={StaticResource Primary}, Dark={StaticResource White}}" />
+        <Setter Property="VisualStateManager.VisualStateGroups">
+            <VisualStateGroupList>
+                <VisualStateGroup x:Name="CommonStates">
+                    <VisualState x:Name="Normal" />
+                    <VisualState x:Name="Disabled">
+                        <VisualState.Setters>
+                            <Setter Property="MinimumTrackColor" Value="{AppThemeBinding Light={StaticResource Gray300}, Dark={StaticResource Gray600}}"/>
+                            <Setter Property="MaximumTrackColor" Value="{AppThemeBinding Light={StaticResource Gray300}, Dark={StaticResource Gray600}}"/>
+                            <Setter Property="ThumbColor" Value="{AppThemeBinding Light={StaticResource Gray300}, Dark={StaticResource Gray600}}"/>
+                        </VisualState.Setters>
+                    </VisualState>
+                </VisualStateGroup>
+            </VisualStateGroupList>
+        </Setter>
+    </Style>
+
+    <Style TargetType="SwipeItem">
+        <Setter Property="BackgroundColor" Value="{AppThemeBinding Light={StaticResource White}, Dark={StaticResource Black}}" />
+    </Style>
+
+    <Style TargetType="Switch">
+        <Setter Property="OnColor" Value="{AppThemeBinding Light={StaticResource Primary}, Dark={StaticResource White}}" />
+        <Setter Property="ThumbColor" Value="{StaticResource White}" />
+        <Setter Property="VisualStateManager.VisualStateGroups">
+            <VisualStateGroupList>
+                <VisualStateGroup x:Name="CommonStates">
+                    <VisualState x:Name="Normal" />
+                    <VisualState x:Name="Disabled">
+                        <VisualState.Setters>
+                            <Setter Property="OnColor" Value="{AppThemeBinding Light={StaticResource Gray300}, Dark={StaticResource Gray600}}" />
+                            <Setter Property="ThumbColor" Value="{AppThemeBinding Light={StaticResource Gray300}, Dark={StaticResource Gray600}}" />
+                        </VisualState.Setters>
+                    </VisualState>
+                    <VisualState x:Name="On">
+                        <VisualState.Setters>
+                            <Setter Property="OnColor" Value="{AppThemeBinding Light={StaticResource Secondary}, Dark={StaticResource Gray200}}" />
+                            <Setter Property="ThumbColor" Value="{AppThemeBinding Light={StaticResource Primary}, Dark={StaticResource White}}" />
+                        </VisualState.Setters>
+                    </VisualState>
+                    <VisualState x:Name="Off">
+                        <VisualState.Setters>
+                            <Setter Property="ThumbColor" Value="{AppThemeBinding Light={StaticResource Gray400}, Dark={StaticResource Gray500}}" />
+                        </VisualState.Setters>
+                    </VisualState>
+                </VisualStateGroup>
+            </VisualStateGroupList>
+        </Setter>
+    </Style>
+
+    <Style TargetType="TimePicker">
+        <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource Gray900}, Dark={StaticResource White}}" />
+        <Setter Property="BackgroundColor" Value="Transparent"/>
+        <Setter Property="FontFamily" Value="OpenSansRegular"/>
+        <Setter Property="FontSize" Value="14"/>
+        <Setter Property="MinimumHeightRequest" Value="44"/>
+        <Setter Property="MinimumWidthRequest" Value="44"/>
+        <Setter Property="VisualStateManager.VisualStateGroups">
+            <VisualStateGroupList>
+                <VisualStateGroup x:Name="CommonStates">
+                    <VisualState x:Name="Normal" />
+                    <VisualState x:Name="Disabled">
+                        <VisualState.Setters>
+                            <Setter Property="TextColor" Value="{AppThemeBinding Light={StaticResource Gray300}, Dark={StaticResource Gray600}}" />
+                        </VisualState.Setters>
+                    </VisualState>
+                </VisualStateGroup>
+            </VisualStateGroupList>
+        </Setter>
+    </Style>
+  
+    <!--
+    <Style TargetType="TitleBar">
+        <Setter Property="MinimumHeightRequest" Value="32"/>
+        <Setter Property="VisualStateManager.VisualStateGroups">
+            <VisualStateGroupList>
+                <VisualStateGroup x:Name="TitleActiveStates">
+                    <VisualState x:Name="TitleBarTitleActive">
+                        <VisualState.Setters>
+                            <Setter Property="BackgroundColor" Value="Transparent" />
+                            <Setter Property="ForegroundColor" Value="{AppThemeBinding Light={StaticResource Black}, Dark={StaticResource White}}" />
+                        </VisualState.Setters>
+                    </VisualState>
+                    <VisualState x:Name="TitleBarTitleInactive">
+                        <VisualState.Setters>
+                            <Setter Property="BackgroundColor" Value="{AppThemeBinding Light={StaticResource White}, Dark={StaticResource Black}}" />
+                            <Setter Property="ForegroundColor" Value="{AppThemeBinding Light={StaticResource Gray400}, Dark={StaticResource Gray500}}" />
+                        </VisualState.Setters>
+                    </VisualState>
+                </VisualStateGroup>
+            </VisualStateGroupList>
+        </Setter>
+    </Style>
+    -->
+
+    <Style TargetType="Page" ApplyToDerivedTypes="True">
+        <Setter Property="Padding" Value="0"/>
+        <Setter Property="BackgroundColor" Value="{AppThemeBinding Light={StaticResource White}, Dark={StaticResource OffBlack}}" />
+    </Style>
+
+    <Style TargetType="Shell" ApplyToDerivedTypes="True">
+        <Setter Property="Shell.BackgroundColor" Value="{AppThemeBinding Light={StaticResource White}, Dark={StaticResource OffBlack}}" />
+        <Setter Property="Shell.ForegroundColor" Value="{AppThemeBinding Light={StaticResource Black}, Dark={StaticResource SecondaryDarkText}}" />
+        <Setter Property="Shell.TitleColor" Value="{AppThemeBinding Light={StaticResource Black}, Dark={StaticResource SecondaryDarkText}}" />
+        <Setter Property="Shell.DisabledColor" Value="{AppThemeBinding Light={StaticResource Gray200}, Dark={StaticResource Gray950}}" />
+        <Setter Property="Shell.UnselectedColor" Value="{AppThemeBinding Light={StaticResource Gray200}, Dark={StaticResource Gray200}}" />
+        <Setter Property="Shell.NavBarHasShadow" Value="False" />
+        <Setter Property="Shell.TabBarBackgroundColor" Value="{AppThemeBinding Light={StaticResource White}, Dark={StaticResource Black}}" />
+        <Setter Property="Shell.TabBarForegroundColor" Value="{AppThemeBinding Light={StaticResource Magenta}, Dark={StaticResource White}}" />
+        <Setter Property="Shell.TabBarTitleColor" Value="{AppThemeBinding Light={StaticResource Magenta}, Dark={StaticResource White}}" />
+        <Setter Property="Shell.TabBarUnselectedColor" Value="{AppThemeBinding Light={StaticResource Gray900}, Dark={StaticResource Gray200}}" />
+    </Style>
+
+    <Style TargetType="NavigationPage">
+        <Setter Property="BarBackgroundColor" Value="{AppThemeBinding Light={StaticResource White}, Dark={StaticResource OffBlack}}" />
+        <Setter Property="BarTextColor" Value="{AppThemeBinding Light={StaticResource Gray200}, Dark={StaticResource White}}" />
+        <Setter Property="IconColor" Value="{AppThemeBinding Light={StaticResource Gray200}, Dark={StaticResource White}}" />
+    </Style>
+
+    <Style TargetType="TabbedPage">
+        <Setter Property="BarBackgroundColor" Value="{AppThemeBinding Light={StaticResource White}, Dark={StaticResource Gray950}}" />
+        <Setter Property="BarTextColor" Value="{AppThemeBinding Light={StaticResource Magenta}, Dark={StaticResource White}}" />
+        <Setter Property="UnselectedTabColor" Value="{AppThemeBinding Light={StaticResource Gray200}, Dark={StaticResource Gray950}}" />
+        <Setter Property="SelectedTabColor" Value="{AppThemeBinding Light={StaticResource Gray950}, Dark={StaticResource Gray200}}" />
+    </Style>
+
+</ResourceDictionary>
--- a/FieldLogger/Services/Ble/BleScanner.cs
+++ b/FieldLogger/Services/Ble/BleScanner.cs
@@ -0,0 +1,81 @@
+using Plugin.BLE;
+using Plugin.BLE.Abstractions.Contracts;
+using Plugin.BLE.Abstractions.EventArgs;
+
+namespace FieldLogger.Services.Ble;
+
+/// <summary>A device found during a BLE scan.</summary>
+public sealed record DiscoveredDevice(Guid Id, string Name, int Rssi);
+
+/// <summary>Thin scan wrapper over Plugin.BLE with per-platform permission handling.</summary>
+public sealed class BleScanner
+{
+    private readonly IAdapter _adapter = CrossBluetoothLE.Current.Adapter;
+
+    public event EventHandler<DiscoveredDevice>? DeviceDiscovered;
+
+    public bool IsScanning => _adapter.IsScanning;
+
+    /// <summary>
+    /// Scans for BLE devices for the given duration, raising DeviceDiscovered as devices appear.
+    /// Only named devices are reported.
+    /// </summary>
+    public async Task ScanAsync(TimeSpan duration, CancellationToken cancellationToken = default)
+    {
+        await EnsurePermissionsAsync();
+
+        if (!CrossBluetoothLE.Current.IsOn)
+            throw new InvalidOperationException("Bluetooth is turned off.");
+
+        void OnDiscovered(object? sender, DeviceEventArgs e)
+        {
+            if (!string.IsNullOrWhiteSpace(e.Device.Name))
+                DeviceDiscovered?.Invoke(this, new DiscoveredDevice(e.Device.Id, e.Device.Name, e.Device.Rssi));
+        }
+
+        _adapter.DeviceDiscovered += OnDiscovered;
+        _adapter.DeviceAdvertised += OnDiscovered;
+        try
+        {
+            using var timeout = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
+            timeout.CancelAfter(duration);
+            _adapter.ScanTimeout = (int)duration.TotalMilliseconds;
+            try
+            {
+                await _adapter.StartScanningForDevicesAsync(cancellationToken: timeout.Token);
+            }
+            catch (OperationCanceledException)
+            {
+                // Scan window elapsed or caller cancelled - both are normal.
+            }
+        }
+        finally
+        {
+            _adapter.DeviceDiscovered -= OnDiscovered;
+            _adapter.DeviceAdvertised -= OnDiscovered;
+            if (_adapter.IsScanning)
+                await _adapter.StopScanningForDevicesAsync();
+        }
+    }
+
+    /// <summary>Requests the runtime permissions BLE scanning needs (Android only; no-op elsewhere).</summary>
+    public static async Task EnsurePermissionsAsync()
+    {
+#if ANDROID
+        if (OperatingSystem.IsAndroidVersionAtLeast(31))
+        {
+            var status = await Permissions.RequestAsync<Permissions.Bluetooth>();
+            if (status != PermissionStatus.Granted)
+                throw new PermissionException("Bluetooth permission was denied.");
+        }
+        else
+        {
+            var status = await Permissions.RequestAsync<Permissions.LocationWhenInUse>();
+            if (status != PermissionStatus.Granted)
+                throw new PermissionException("Location permission (required for BLE scanning) was denied.");
+        }
+#else
+        await Task.CompletedTask;
+#endif
+    }
+}
--- a/FieldLogger/Services/Ble/BleSerialClient.cs
+++ b/FieldLogger/Services/Ble/BleSerialClient.cs
@@ -0,0 +1,165 @@
+using System.Text;
+using Plugin.BLE;
+using Plugin.BLE.Abstractions;
+using Plugin.BLE.Abstractions.Contracts;
+using Plugin.BLE.Abstractions.EventArgs;
+
+namespace FieldLogger.Services.Ble;
+
+/// <summary>
+/// Line-oriented serial client over a BLE GATT "UART" style service
+/// (one notify characteristic for RX, one write characteristic for TX).
+/// Both the UM receiver and the Maglink RTK receiver expose this pattern.
+/// </summary>
+public sealed class BleSerialClient : IAsyncDisposable
+{
+    private readonly IAdapter _adapter;
+    private readonly StringBuilder _rxBuffer = new();
+    private IDevice? _device;
+    private ICharacteristic? _notifyChar;
+    private ICharacteristic? _writeChar;
+
+    public event EventHandler<string>? LineReceived;
+    public event EventHandler? Disconnected;
+
+    public bool IsConnected => _device?.State == DeviceState.Connected;
+    public string? DeviceName => _device?.Name;
+    public Guid? DeviceId => _device?.Id;
+
+    public BleSerialClient()
+    {
+        _adapter = CrossBluetoothLE.Current.Adapter;
+        _adapter.DeviceDisconnected += OnDeviceDisconnected;
+        _adapter.DeviceConnectionLost += OnDeviceConnectionLost;
+    }
+
+    /// <summary>
+    /// Connects to a known device by id, discovers the given service, and
+    /// enables notifications. Throws on failure.
+    /// </summary>
+    public async Task ConnectAsync(Guid deviceId, Guid serviceUuid, Guid notifyUuid, Guid writeUuid,
+        CancellationToken cancellationToken = default)
+    {
+        await DisconnectAsync().ConfigureAwait(false);
+
+        var device = await _adapter.ConnectToKnownDeviceAsync(
+            deviceId,
+            new ConnectParameters(autoConnect: false, forceBleTransport: true),
+            cancellationToken).ConfigureAwait(false);
+
+        try
+        {
+            // UM receivers request MTU 247; only has an effect on Android, harmless elsewhere.
+            try { await device.RequestMtuAsync(247).ConfigureAwait(false); }
+            catch { /* not supported on this platform */ }
+
+            var service = await device.GetServiceAsync(serviceUuid, cancellationToken).ConfigureAwait(false)
+                ?? throw new InvalidOperationException($"Service {serviceUuid} not found on {device.Name}.");
+
+            var notifyChar = await service.GetCharacteristicAsync(notifyUuid).ConfigureAwait(false)
+                ?? throw new InvalidOperationException($"Notify characteristic {notifyUuid} not found.");
+            var writeChar = await service.GetCharacteristicAsync(writeUuid).ConfigureAwait(false)
+                ?? throw new InvalidOperationException($"Write characteristic {writeUuid} not found.");
+
+            writeChar.WriteType =
+                writeChar.Properties.HasFlag(CharacteristicPropertyType.WriteWithoutResponse)
+                    ? CharacteristicWriteType.WithoutResponse
+                    : CharacteristicWriteType.WithResponse;
+
+            notifyChar.ValueUpdated += OnValueUpdated;
+            await notifyChar.StartUpdatesAsync(cancellationToken).ConfigureAwait(false);
+
+            _device = device;
+            _notifyChar = notifyChar;
+            _writeChar = writeChar;
+        }
+        catch
+        {
+            try { await _adapter.DisconnectDeviceAsync(device).ConfigureAwait(false); } catch { }
+            throw;
+        }
+    }
+
+    /// <summary>Writes an ASCII string followed by CR+LF to the device.</summary>
+    public Task WriteLineAsync(string text, CancellationToken cancellationToken = default)
+        => WriteAsync(text + "\r\n", cancellationToken);
+
+    public async Task WriteAsync(string text, CancellationToken cancellationToken = default)
+    {
+        var writeChar = _writeChar ?? throw new InvalidOperationException("Not connected.");
+        await writeChar.WriteAsync(Encoding.ASCII.GetBytes(text), cancellationToken).ConfigureAwait(false);
+    }
+
+    public async Task DisconnectAsync()
+    {
+        var device = _device;
+        var notifyChar = _notifyChar;
+        _device = null;
+        _notifyChar = null;
+        _writeChar = null;
+
+        if (notifyChar is not null)
+        {
+            notifyChar.ValueUpdated -= OnValueUpdated;
+            try { await notifyChar.StopUpdatesAsync().ConfigureAwait(false); } catch { }
+        }
+
+        if (device is not null)
+        {
+            try { await _adapter.DisconnectDeviceAsync(device).ConfigureAwait(false); } catch { }
+            device.Dispose();
+        }
+
+        lock (_rxBuffer)
+            _rxBuffer.Clear();
+    }
+
+    private void OnValueUpdated(object? sender, CharacteristicUpdatedEventArgs e)
+    {
+        var bytes = e.Characteristic.Value;
+        if (bytes is null || bytes.Length == 0)
+            return;
+
+        List<string> lines = new();
+        lock (_rxBuffer)
+        {
+            _rxBuffer.Append(Encoding.ASCII.GetString(bytes));
+            var buffered = _rxBuffer.ToString();
+            int newline;
+            while ((newline = buffered.IndexOf('\n')) >= 0)
+            {
+                var line = buffered[..newline].TrimEnd('\r');
+                buffered = buffered[(newline + 1)..];
+                if (line.Length > 0)
+                    lines.Add(line);
+            }
+            _rxBuffer.Clear();
+            _rxBuffer.Append(buffered);
+        }
+
+        foreach (var line in lines)
+            LineReceived?.Invoke(this, line);
+    }
+
+    private void OnDeviceDisconnected(object? sender, DeviceEventArgs e) => HandleDisconnect(e.Device);
+
+    private void OnDeviceConnectionLost(object? sender, DeviceErrorEventArgs e) => HandleDisconnect(e.Device);
+
+    private void HandleDisconnect(IDevice device)
+    {
+        if (_device is null || device.Id != _device.Id)
+            return;
+
+        _device = null;
+        _notifyChar = null;
+        _writeChar = null;
+        Disconnected?.Invoke(this, EventArgs.Empty);
+    }
+
+    public async ValueTask DisposeAsync()
+    {
+        _adapter.DeviceDisconnected -= OnDeviceDisconnected;
+        _adapter.DeviceConnectionLost -= OnDeviceConnectionLost;
+        await DisconnectAsync().ConfigureAwait(false);
+    }
+}
--- a/FieldLogger/Services/Data/AppDatabase.cs
+++ b/FieldLogger/Services/Data/AppDatabase.cs
@@ -0,0 +1,90 @@
+using FieldLogger.Models;
+using SQLite;
+
+namespace FieldLogger.Services.Data;
+
+/// <summary>Local SQLite store for jobs and logged points.</summary>
+public sealed class AppDatabase
+{
+    private readonly Lazy<Task<SQLiteAsyncConnection>> _connection;
+
+    public AppDatabase()
+    {
+        _connection = new Lazy<Task<SQLiteAsyncConnection>>(async () =>
+        {
+            var path = Path.Combine(FileSystem.AppDataDirectory, "fieldlogger.db3");
+            var db = new SQLiteAsyncConnection(path,
+                SQLiteOpenFlags.ReadWrite | SQLiteOpenFlags.Create | SQLiteOpenFlags.SharedCache);
+            await db.CreateTableAsync<Job>();
+            await db.CreateTableAsync<LoggedPoint>();
+            return db;
+        });
+    }
+
+    private Task<SQLiteAsyncConnection> Db => _connection.Value;
+
+    // ---- Jobs ----
+
+    public async Task<List<Job>> GetJobsAsync()
+    {
+        var db = await Db;
+        return await db.Table<Job>().OrderByDescending(j => j.CreatedUtc).ToListAsync();
+    }
+
+    public async Task<Job?> GetJobAsync(int id)
+    {
+        var db = await Db;
+        return await db.Table<Job>().Where(j => j.Id == id).FirstOrDefaultAsync();
+    }
+
+    public async Task<Job> CreateJobAsync(string name, string notes = "")
+    {
+        var db = await Db;
+        var job = new Job { Name = name, Notes = notes };
+        await db.InsertAsync(job);
+        return job;
+    }
+
+    public async Task UpdateJobAsync(Job job)
+    {
+        var db = await Db;
+        await db.UpdateAsync(job);
+    }
+
+    public async Task DeleteJobAsync(int jobId)
+    {
+        var db = await Db;
+        await db.Table<LoggedPoint>().DeleteAsync(p => p.JobId == jobId);
+        await db.DeleteAsync<Job>(jobId);
+    }
+
+    // ---- Points ----
+
+    public async Task<int> AddPointAsync(LoggedPoint point)
+    {
+        var db = await Db;
+        await db.InsertAsync(point);
+        return point.Id;
+    }
+
+    public async Task<List<LoggedPoint>> GetPointsAsync(int jobId)
+    {
+        var db = await Db;
+        return await db.Table<LoggedPoint>()
+            .Where(p => p.JobId == jobId)
+            .OrderBy(p => p.TimestampUtc)
+            .ToListAsync();
+    }
+
+    public async Task<int> GetPointCountAsync(int jobId)
+    {
+        var db = await Db;
+        return await db.Table<LoggedPoint>().Where(p => p.JobId == jobId).CountAsync();
+    }
+
+    public async Task DeletePointAsync(int pointId)
+    {
+        var db = await Db;
+        await db.DeleteAsync<LoggedPoint>(pointId);
+    }
+}
--- a/FieldLogger/Services/DeviceConnectionManager.cs
+++ b/FieldLogger/Services/DeviceConnectionManager.cs
@@ -0,0 +1,175 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using FieldLogger.Models;
+using FieldLogger.Services.Ble;
+using Microsoft.Extensions.Logging;
+
+namespace FieldLogger.Services;
+
+public enum ConnectionState { Disconnected, Connecting, Connected }
+
+/// <summary>
+/// Owns the lifetime of both device connections: auto-connects to saved devices
+/// at startup, reconnects with backoff when a connection drops, and exposes
+/// bindable state for the UI.
+/// </summary>
+public sealed partial class DeviceConnectionManager : ObservableObject
+{
+    private static readonly TimeSpan[] RetryDelays =
+        [TimeSpan.FromSeconds(2), TimeSpan.FromSeconds(5), TimeSpan.FromSeconds(10), TimeSpan.FromSeconds(30)];
+
+    private readonly UmReceiverService _locator;
+    private readonly MaglinkService _gps;
+    private readonly SettingsService _settings;
+    private readonly ILogger<DeviceConnectionManager> _logger;
+
+    private CancellationTokenSource? _locatorCts;
+    private CancellationTokenSource? _gpsCts;
+
+    [ObservableProperty]
+    private ConnectionState _locatorState;
+
+    [ObservableProperty]
+    private ConnectionState _gpsState;
+
+    [ObservableProperty]
+    private string? _locatorName;
+
+    [ObservableProperty]
+    private string? _gpsName;
+
+    public UmReceiverService Locator => _locator;
+    public MaglinkService Gps => _gps;
+
+    public DeviceConnectionManager(UmReceiverService locator, MaglinkService gps,
+        SettingsService settings, ILogger<DeviceConnectionManager> logger)
+    {
+        _locator = locator;
+        _gps = gps;
+        _settings = settings;
+        _logger = logger;
+
+        _locator.Disconnected += (_, _) => OnDeviceDropped(DeviceKind.Locator);
+        _gps.Disconnected += (_, _) => OnDeviceDropped(DeviceKind.RtkGps);
+
+        LocatorName = settings.GetSavedDeviceName(DeviceKind.Locator);
+        GpsName = settings.GetSavedDeviceName(DeviceKind.RtkGps);
+    }
+
+    /// <summary>True when a device of this kind has been selected at least once.</summary>
+    public bool HasSavedDevice(DeviceKind kind) => _settings.GetSavedDeviceId(kind) is not null;
+
+    /// <summary>Kicks off auto-connect attempts for every saved device. Safe to call repeatedly.</summary>
+    public void Start()
+    {
+        if (HasSavedDevice(DeviceKind.Locator) && LocatorState == ConnectionState.Disconnected)
+            _ = ConnectLoopAsync(DeviceKind.Locator);
+        if (HasSavedDevice(DeviceKind.RtkGps) && GpsState == ConnectionState.Disconnected)
+            _ = ConnectLoopAsync(DeviceKind.RtkGps);
+    }
+
+    /// <summary>Saves a newly selected device and connects to it, replacing any previous device.</summary>
+    public async Task UseDeviceAsync(DeviceKind kind, Guid id, string name)
+    {
+        CancelLoop(kind);
+        await (kind == DeviceKind.Locator ? _locator.DisconnectAsync() : _gps.DisconnectAsync());
+
+        _settings.SaveDevice(kind, id, name);
+        if (kind == DeviceKind.Locator)
+            LocatorName = name;
+        else
+            GpsName = name;
+
+        _ = ConnectLoopAsync(kind);
+    }
+
+    public async Task ForgetDeviceAsync(DeviceKind kind)
+    {
+        CancelLoop(kind);
+        await (kind == DeviceKind.Locator ? _locator.DisconnectAsync() : _gps.DisconnectAsync());
+        _settings.ClearDevice(kind);
+
+        if (kind == DeviceKind.Locator)
+        {
+            LocatorName = null;
+            LocatorState = ConnectionState.Disconnected;
+        }
+        else
+        {
+            GpsName = null;
+            GpsState = ConnectionState.Disconnected;
+        }
+    }
+
+    private void OnDeviceDropped(DeviceKind kind)
+    {
+        _logger.LogInformation("{Kind} connection lost; scheduling reconnect", kind);
+        SetState(kind, ConnectionState.Disconnected);
+        _ = ConnectLoopAsync(kind);
+    }
+
+    private async Task ConnectLoopAsync(DeviceKind kind)
+    {
+        var id = _settings.GetSavedDeviceId(kind);
+        if (id is null)
+            return;
+
+        CancelLoop(kind);
+        var cts = new CancellationTokenSource();
+        if (kind == DeviceKind.Locator)
+            _locatorCts = cts;
+        else
+            _gpsCts = cts;
+
+        SetState(kind, ConnectionState.Connecting);
+
+        for (var attempt = 0; !cts.Token.IsCancellationRequested; attempt++)
+        {
+            try
+            {
+                await BleScanner.EnsurePermissionsAsync();
+                if (kind == DeviceKind.Locator)
+                    await _locator.ConnectAsync(id.Value, cts.Token);
+                else
+                    await _gps.ConnectAsync(id.Value, cts.Token);
+
+                SetState(kind, ConnectionState.Connected);
+                _logger.LogInformation("{Kind} connected", kind);
+                return;
+            }
+            catch (OperationCanceledException)
+            {
+                return;
+            }
+            catch (Exception ex)
+            {
+                _logger.LogWarning(ex, "{Kind} connect attempt {Attempt} failed", kind, attempt + 1);
+                var delay = RetryDelays[Math.Min(attempt, RetryDelays.Length - 1)];
+                try { await Task.Delay(delay, cts.Token); }
+                catch (OperationCanceledException) { return; }
+            }
+        }
+    }
+
+    private void CancelLoop(DeviceKind kind)
+    {
+        var cts = kind == DeviceKind.Locator ? _locatorCts : _gpsCts;
+        cts?.Cancel();
+        cts?.Dispose();
+        if (kind == DeviceKind.Locator)
+            _locatorCts = null;
+        else
+            _gpsCts = null;
+    }
+
+    private void SetState(DeviceKind kind, ConnectionState state)
+    {
+        // Property change notifications must fire on the UI thread for bindings.
+        MainThread.BeginInvokeOnMainThread(() =>
+        {
+            if (kind == DeviceKind.Locator)
+                LocatorState = state;
+            else
+                GpsState = state;
+        });
+    }
+}
--- a/FieldLogger/Services/MaglinkService.cs
+++ b/FieldLogger/Services/MaglinkService.cs
@@ -0,0 +1,98 @@
+using FieldLogger.Models;
+using FieldLogger.Services.Ble;
+using Microsoft.Extensions.Logging;
+
+namespace FieldLogger.Services;
+
+/// <summary>
+/// Manages the connection to the Maglink (H11) RTK GNSS receiver: parses the
+/// $GNPOS / $GNDEV custom NMEA stream and sends AT configuration commands.
+/// </summary>
+public sealed class MaglinkService : IAsyncDisposable
+{
+    public static readonly Guid ServiceUuid = Guid.Parse("0000fff0-0000-1000-8000-00805f9b34fb");
+    public static readonly Guid NotifyUuid = Guid.Parse("0000fff2-0000-1000-8000-00805f9b34fb");
+    public static readonly Guid WriteUuid = Guid.Parse("0000fff2-0000-1000-8000-00805f9b34fb");
+
+    private readonly BleSerialClient _client = new();
+    private readonly ILogger<MaglinkService> _logger;
+
+    public GnssFix? LatestFix { get; private set; }
+    public GnssDeviceInfo? DeviceInfo { get; private set; }
+    public bool IsConnected => _client.IsConnected;
+    public string? DeviceName => _client.DeviceName;
+
+    public event EventHandler<GnssFix>? FixReceived;
+    public event EventHandler<GnssDeviceInfo>? DeviceInfoReceived;
+    public event EventHandler? Disconnected;
+
+    /// <summary>Device-name filter for scan results (ML-*).</summary>
+    public static bool IsMaglinkName(string? name) =>
+        name is not null && name.StartsWith("ML-", StringComparison.OrdinalIgnoreCase);
+
+    public MaglinkService(ILogger<MaglinkService> logger)
+    {
+        _logger = logger;
+        _client.LineReceived += OnLineReceived;
+        _client.Disconnected += (_, _) => Disconnected?.Invoke(this, EventArgs.Empty);
+    }
+
+    public async Task ConnectAsync(Guid deviceId, CancellationToken cancellationToken = default)
+    {
+        await _client.ConnectAsync(deviceId, ServiceUuid, NotifyUuid, WriteUuid, cancellationToken);
+
+        // Custom mode with GNPOS + GNDEV only - everything the app needs, minimal traffic.
+        await SendCommandAsync("AT+BT_OUT=SET,1,0,1,1,0,0,0,0,0,0", cancellationToken);
+    }
+
+    /// <summary>Sends an AT command (terminator appended automatically).</summary>
+    public Task SendCommandAsync(string command, CancellationToken cancellationToken = default)
+        => _client.WriteLineAsync(command, cancellationToken);
+
+    public Task DisconnectAsync() => _client.DisconnectAsync();
+
+    /// <summary>A fix received within the last few seconds, or null if the stream has gone stale.</summary>
+    public GnssFix? FreshFix(TimeSpan? maxAge = null)
+    {
+        var fix = LatestFix;
+        if (fix is null)
+            return null;
+        return DateTime.UtcNow - fix.ReceivedUtc <= (maxAge ?? TimeSpan.FromSeconds(5)) ? fix : null;
+    }
+
+    private void OnLineReceived(object? sender, string line)
+    {
+        if (line.StartsWith("$GNPOS,", StringComparison.Ordinal))
+        {
+            if (!NmeaSentence.VerifyChecksum(line))
+            {
+                _logger.LogWarning("GNPOS checksum failed: {Line}", line);
+                return;
+            }
+            var fix = GnssFix.TryParse(line);
+            if (fix is not null)
+            {
+                LatestFix = fix;
+                FixReceived?.Invoke(this, fix);
+            }
+        }
+        else if (line.StartsWith("$GNDEV,", StringComparison.Ordinal))
+        {
+            if (!NmeaSentence.VerifyChecksum(line))
+                return;
+            var info = GnssDeviceInfo.TryParse(line);
+            if (info is not null)
+            {
+                DeviceInfo = info;
+                DeviceInfoReceived?.Invoke(this, info);
+            }
+        }
+        else
+        {
+            // AT command responses and anything else.
+            _logger.LogDebug("Maglink rx: {Line}", line);
+        }
+    }
+
+    public ValueTask DisposeAsync() => _client.DisposeAsync();
+}
--- a/FieldLogger/Services/PointLogger.cs
+++ b/FieldLogger/Services/PointLogger.cs
@@ -0,0 +1,67 @@
+using FieldLogger.Models;
+using FieldLogger.Services.Data;
+using Microsoft.Extensions.Logging;
+
+namespace FieldLogger.Services;
+
+/// <summary>
+/// Joins UM receiver log packets with the current GNSS fix and persists them
+/// under the active job. Runs for the lifetime of the app.
+/// </summary>
+public sealed class PointLogger
+{
+    private readonly UmReceiverService _locator;
+    private readonly MaglinkService _gps;
+    private readonly AppDatabase _database;
+    private readonly SettingsService _settings;
+    private readonly ILogger<PointLogger> _logger;
+
+    /// <summary>Raised (on the UI thread) after a point is saved.</summary>
+    public event EventHandler<LoggedPoint>? PointSaved;
+
+    /// <summary>Raised when a packet arrives but no active job is selected, so the point was dropped.</summary>
+    public event EventHandler? PacketIgnoredNoJob;
+
+    public PointLogger(UmReceiverService locator, MaglinkService gps, AppDatabase database,
+        SettingsService settings, ILogger<PointLogger> logger)
+    {
+        _locator = locator;
+        _gps = gps;
+        _database = database;
+        _settings = settings;
+        _logger = logger;
+
+        _locator.PacketReceived += OnPacketReceived;
+    }
+
+    private void OnPacketReceived(object? sender, UmLogPacket packet)
+    {
+        _ = HandlePacketAsync(packet);
+    }
+
+    private async Task HandlePacketAsync(UmLogPacket packet)
+    {
+        try
+        {
+            var jobId = _settings.ActiveJobId;
+            if (jobId is null)
+            {
+                _logger.LogWarning("Log packet received but no active job; point dropped");
+                MainThread.BeginInvokeOnMainThread(() => PacketIgnoredNoJob?.Invoke(this, EventArgs.Empty));
+                return;
+            }
+
+            var fix = _gps.FreshFix();
+            var point = LoggedPoint.From(jobId.Value, packet, _locator.DeviceInfo, fix, _gps.DeviceInfo);
+            await _database.AddPointAsync(point);
+
+            _logger.LogInformation("Point {Id} saved to job {JobId} (gps valid: {GpsValid})",
+                point.Id, jobId, point.GpsValid);
+            MainThread.BeginInvokeOnMainThread(() => PointSaved?.Invoke(this, point));
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to save logged point");
+        }
+    }
+}
--- a/FieldLogger/Services/SettingsService.cs
+++ b/FieldLogger/Services/SettingsService.cs
@@ -0,0 +1,58 @@
+using FieldLogger.Models;
+
+namespace FieldLogger.Services;
+
+/// <summary>Persisted app settings: paired device identities, active job, map key.</summary>
+public sealed class SettingsService
+{
+    private const string LocatorIdKey = "device.locator.id";
+    private const string LocatorNameKey = "device.locator.name";
+    private const string RtkIdKey = "device.rtk.id";
+    private const string RtkNameKey = "device.rtk.name";
+    private const string ActiveJobKey = "job.active.id";
+    private const string MapsApiKeyKey = "maps.apikey";
+
+    public Guid? GetSavedDeviceId(DeviceKind kind)
+    {
+        var raw = Preferences.Default.Get(IdKey(kind), string.Empty);
+        return Guid.TryParse(raw, out var id) ? id : null;
+    }
+
+    public string? GetSavedDeviceName(DeviceKind kind)
+    {
+        var name = Preferences.Default.Get(NameKey(kind), string.Empty);
+        return string.IsNullOrEmpty(name) ? null : name;
+    }
+
+    public void SaveDevice(DeviceKind kind, Guid id, string name)
+    {
+        Preferences.Default.Set(IdKey(kind), id.ToString());
+        Preferences.Default.Set(NameKey(kind), name);
+    }
+
+    public void ClearDevice(DeviceKind kind)
+    {
+        Preferences.Default.Remove(IdKey(kind));
+        Preferences.Default.Remove(NameKey(kind));
+    }
+
+    public int? ActiveJobId
+    {
+        get
+        {
+            var id = Preferences.Default.Get(ActiveJobKey, 0);
+            return id > 0 ? id : null;
+        }
+        set => Preferences.Default.Set(ActiveJobKey, value ?? 0);
+    }
+
+    /// <summary>Google Maps JavaScript API key used by the Windows WebView map.</summary>
+    public string GoogleMapsApiKey
+    {
+        get => Preferences.Default.Get(MapsApiKeyKey, string.Empty);
+        set => Preferences.Default.Set(MapsApiKeyKey, value);
+    }
+
+    private static string IdKey(DeviceKind kind) => kind == DeviceKind.Locator ? LocatorIdKey : RtkIdKey;
+    private static string NameKey(DeviceKind kind) => kind == DeviceKind.Locator ? LocatorNameKey : RtkNameKey;
+}
--- a/FieldLogger/Services/Sync/IMqttSyncService.cs
+++ b/FieldLogger/Services/Sync/IMqttSyncService.cs
@@ -0,0 +1,27 @@
+using FieldLogger.Models;
+
+namespace FieldLogger.Services.Sync;
+
+/// <summary>
+/// Placeholder for the future MQTT synchronization layer:
+/// - subscribe to receive jobs configured on the server
+/// - publish logged points as they are captured
+/// - reconcile the Synced flags on <see cref="Job"/> and <see cref="LoggedPoint"/>
+/// Planned implementation: MQTTnet client against the configured broker.
+/// </summary>
+public interface IMqttSyncService
+{
+    bool IsConnected { get; }
+    Task ConnectAsync(CancellationToken cancellationToken = default);
+    Task DisconnectAsync();
+    Task PublishPointAsync(LoggedPoint point, CancellationToken cancellationToken = default);
+}
+
+/// <summary>No-op stand-in until the MQTT backend exists.</summary>
+public sealed class NullMqttSyncService : IMqttSyncService
+{
+    public bool IsConnected => false;
+    public Task ConnectAsync(CancellationToken cancellationToken = default) => Task.CompletedTask;
+    public Task DisconnectAsync() => Task.CompletedTask;
+    public Task PublishPointAsync(LoggedPoint point, CancellationToken cancellationToken = default) => Task.CompletedTask;
+}
--- a/FieldLogger/Services/UmReceiverService.cs
+++ b/FieldLogger/Services/UmReceiverService.cs
@@ -0,0 +1,88 @@
+using FieldLogger.Models;
+using FieldLogger.Services.Ble;
+using Microsoft.Extensions.Logging;
+
+namespace FieldLogger.Services;
+
+/// <summary>
+/// Manages the connection to an Underground Magnetics locating receiver and
+/// its push-button data-logging (PBDL) protocol.
+/// </summary>
+public sealed class UmReceiverService : IAsyncDisposable
+{
+    // UM Receiver BLE External Logging API v1.2:
+    // serial port service with notify (RX) and write-no-response (TX) characteristics.
+    public static readonly Guid ServiceUuid = Guid.Parse("554d0000-261f-677e-a6f1-54c57aa996d4");
+    public static readonly Guid NotifyUuid = Guid.Parse("554d0001-261f-677e-a6f1-54c57aa996d4");
+    public static readonly Guid WriteUuid = Guid.Parse("554d0002-261f-677e-a6f1-54c57aa996d4");
+
+    private readonly BleSerialClient _client = new();
+    private readonly ILogger<UmReceiverService> _logger;
+
+    public UmDeviceInfo? DeviceInfo { get; private set; }
+    public bool IsConnected => _client.IsConnected;
+    public string? DeviceName => _client.DeviceName;
+
+    /// <summary>Raised when the operator presses the log button on the receiver.</summary>
+    public event EventHandler<UmLogPacket>? PacketReceived;
+    public event EventHandler<UmDeviceInfo>? DeviceInfoReceived;
+    public event EventHandler? Disconnected;
+
+    public UmReceiverService(ILogger<UmReceiverService> logger)
+    {
+        _logger = logger;
+        _client.LineReceived += OnLineReceived;
+        _client.Disconnected += (_, _) => Disconnected?.Invoke(this, EventArgs.Empty);
+    }
+
+    /// <summary>Device-name filter for scan results (UMRX_* for most brands, DT100_* for Leica).</summary>
+    public static bool IsUmReceiverName(string? name) =>
+        name is not null &&
+        (name.StartsWith("UMRX", StringComparison.OrdinalIgnoreCase) ||
+         name.StartsWith("DT100", StringComparison.OrdinalIgnoreCase));
+
+    public async Task ConnectAsync(Guid deviceId, CancellationToken cancellationToken = default)
+    {
+        await _client.ConnectAsync(deviceId, ServiceUuid, NotifyUuid, WriteUuid, cancellationToken);
+        await EnableLoggingAsync(cancellationToken);
+    }
+
+    /// <summary>Enables push-button data logging. The first enable triggers the info string.</summary>
+    public Task EnableLoggingAsync(CancellationToken cancellationToken = default)
+        => _client.WriteLineAsync("$UMPBDL,1", cancellationToken);
+
+    public Task DisableLoggingAsync(CancellationToken cancellationToken = default)
+        => _client.WriteLineAsync("$UMPBDL,0", cancellationToken);
+
+    public Task DisconnectAsync() => _client.DisconnectAsync();
+
+    private void OnLineReceived(object? sender, string line)
+    {
+        _logger.LogDebug("UM rx: {Line}", line);
+
+        // Bare command acknowledgements.
+        var trimmed = line.Trim();
+        if (trimmed.Equals("OK", StringComparison.OrdinalIgnoreCase) ||
+            trimmed.Equals("ERROR", StringComparison.OrdinalIgnoreCase))
+            return;
+
+        var packet = UmLogPacket.TryParse(line);
+        if (packet is not null)
+        {
+            PacketReceived?.Invoke(this, packet);
+            return;
+        }
+
+        var info = UmDeviceInfo.TryParse(line);
+        if (info is not null)
+        {
+            DeviceInfo = info;
+            DeviceInfoReceived?.Invoke(this, info);
+            return;
+        }
+
+        _logger.LogWarning("UM receiver sent unrecognized line: {Line}", line);
+    }
+
+    public ValueTask DisposeAsync() => _client.DisposeAsync();
+}
--- a/FieldLogger/ViewModels/DeviceScanViewModel.cs
+++ b/FieldLogger/ViewModels/DeviceScanViewModel.cs
@@ -0,0 +1,107 @@
+using System.Collections.ObjectModel;
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using FieldLogger.Models;
+using FieldLogger.Services;
+using FieldLogger.Services.Ble;
+
+namespace FieldLogger.ViewModels;
+
+[QueryProperty(nameof(KindName), "kind")]
+public sealed partial class DeviceScanViewModel : ObservableObject
+{
+    private readonly BleScanner _scanner;
+    private readonly DeviceConnectionManager _manager;
+    private CancellationTokenSource? _scanCts;
+
+    [ObservableProperty]
+    private string _kindName = nameof(DeviceKind.Locator);
+
+    [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(ScanButtonText))]
+    private bool _isScanning;
+
+    [ObservableProperty]
+    private string _title = "Select Device";
+
+    [ObservableProperty]
+    private string _hint = "";
+
+    public ObservableCollection<DiscoveredDevice> Devices { get; } = new();
+
+    public DeviceKind Kind => Enum.TryParse<DeviceKind>(KindName, out var k) ? k : DeviceKind.Locator;
+
+    public string ScanButtonText => IsScanning ? "Scanning…" : "Scan Again";
+
+    public DeviceScanViewModel(BleScanner scanner, DeviceConnectionManager manager)
+    {
+        _scanner = scanner;
+        _manager = manager;
+        _scanner.DeviceDiscovered += OnDeviceDiscovered;
+    }
+
+    partial void OnKindNameChanged(string value)
+    {
+        Title = Kind == DeviceKind.Locator ? "Select Locating Receiver" : "Select RTK GPS Receiver";
+        Hint = Kind == DeviceKind.Locator
+            ? "Looking for UM receivers (UMRX / DT100). Make sure Bluetooth is enabled on the receiver."
+            : "Looking for Maglink RTK receivers. Make sure the receiver is powered on.";
+    }
+
+    [RelayCommand]
+    public async Task ScanAsync()
+    {
+        if (IsScanning)
+            return;
+
+        Devices.Clear();
+        IsScanning = true;
+        _scanCts = new CancellationTokenSource();
+        try
+        {
+            await _scanner.ScanAsync(TimeSpan.FromSeconds(12), _scanCts.Token);
+        }
+        catch (Exception ex)
+        {
+            await Shell.Current.DisplayAlert("Scan Failed", ex.Message, "OK");
+        }
+        finally
+        {
+            IsScanning = false;
+            _scanCts?.Dispose();
+            _scanCts = null;
+        }
+    }
+
+    public void StopScan() => _scanCts?.Cancel();
+
+    [RelayCommand]
+    private async Task SelectAsync(DiscoveredDevice device)
+    {
+        StopScan();
+        await _manager.UseDeviceAsync(Kind, device.Id, device.Name);
+        await Shell.Current.GoToAsync("..");
+    }
+
+    private void OnDeviceDiscovered(object? sender, DiscoveredDevice device)
+    {
+        // Filter by device name prefix based on device type.
+        if (Kind == DeviceKind.Locator && !UmReceiverService.IsUmReceiverName(device.Name))
+            return;
+        if (Kind == DeviceKind.Maglink && !MaglinkService.IsMaglinkName(device.Name))
+            return;
+
+        MainThread.BeginInvokeOnMainThread(() =>
+        {
+            var existing = Devices.FirstOrDefault(d => d.Id == device.Id);
+            if (existing is not null)
+                Devices.Remove(existing);
+
+            // Keep the list sorted by signal strength.
+            var index = 0;
+            while (index < Devices.Count && Devices[index].Rssi >= device.Rssi)
+                index++;
+            Devices.Insert(index, device);
+        });
+    }
+}
--- a/FieldLogger/ViewModels/HomeViewModel.cs
+++ b/FieldLogger/ViewModels/HomeViewModel.cs
@@ -0,0 +1,149 @@
+using System.Collections.ObjectModel;
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using FieldLogger.Models;
+using FieldLogger.Services;
+using FieldLogger.Services.Data;
+
+namespace FieldLogger.ViewModels;
+
+public sealed partial class HomeViewModel : ObservableObject
+{
+    private readonly DeviceConnectionManager _manager;
+    private readonly MaglinkService _gps;
+    private readonly PointLogger _pointLogger;
+    private readonly AppDatabase _database;
+    private readonly SettingsService _settings;
+
+    public DeviceConnectionManager Manager => _manager;
+
+    [ObservableProperty]
+    private string _activeJobName = "No active job";
+
+    [ObservableProperty]
+    private bool _hasActiveJob;
+
+    [ObservableProperty]
+    private int _pointCount;
+
+    [ObservableProperty]
+    private string _fixSummary = "Waiting for GPS…";
+
+    [ObservableProperty]
+    private string _fixStatusLabel = "—";
+
+    [ObservableProperty]
+    private string _fixAccuracy = "";
+
+    public ObservableCollection<LoggedPoint> RecentPoints { get; } = new();
+
+    public HomeViewModel(DeviceConnectionManager manager, MaglinkService gps,
+        PointLogger pointLogger, AppDatabase database, SettingsService settings)
+    {
+        _manager = manager;
+        _gps = gps;
+        _pointLogger = pointLogger;
+        _database = database;
+        _settings = settings;
+
+        _gps.FixReceived += OnFixReceived;
+        _pointLogger.PointSaved += OnPointSaved;
+        _pointLogger.PacketIgnoredNoJob += OnPacketIgnoredNoJob;
+    }
+
+    /// <summary>Called from the page's OnAppearing.</summary>
+    public async Task InitializeAsync()
+    {
+        // First launch: nothing saved yet, send the user to device selection.
+        if (!_manager.HasSavedDevice(DeviceKind.Locator) && !_manager.HasSavedDevice(DeviceKind.RtkGps))
+        {
+            await Shell.Current.GoToAsync($"devicescan?kind={DeviceKind.Locator}");
+            return;
+        }
+
+        _manager.Start();
+        await RefreshJobAsync();
+    }
+
+    public async Task RefreshJobAsync()
+    {
+        var jobId = _settings.ActiveJobId;
+        if (jobId is null)
+        {
+            HasActiveJob = false;
+            ActiveJobName = "No active job";
+            PointCount = 0;
+            RecentPoints.Clear();
+            return;
+        }
+
+        var job = await _database.GetJobAsync(jobId.Value);
+        if (job is null)
+        {
+            _settings.ActiveJobId = null;
+            await RefreshJobAsync();
+            return;
+        }
+
+        HasActiveJob = true;
+        ActiveJobName = job.Name;
+        PointCount = await _database.GetPointCountAsync(job.Id);
+
+        var points = await _database.GetPointsAsync(job.Id);
+        RecentPoints.Clear();
+        foreach (var p in points.OrderByDescending(p => p.TimestampUtc).Take(10))
+            RecentPoints.Add(p);
+    }
+
+    [RelayCommand]
+    private async Task NewJobAsync()
+    {
+        var name = await Shell.Current.DisplayPromptAsync("New Job", "Job name:",
+            placeholder: $"Job {DateTime.Now:yyyy-MM-dd}");
+        if (string.IsNullOrWhiteSpace(name))
+            return;
+
+        var job = await _database.CreateJobAsync(name.Trim());
+        _settings.ActiveJobId = job.Id;
+        await RefreshJobAsync();
+    }
+
+    [RelayCommand]
+    private Task SelectJobAsync() => Shell.Current.GoToAsync("//jobs");
+
+    [RelayCommand]
+    private Task SelectLocatorAsync() => Shell.Current.GoToAsync($"devicescan?kind={DeviceKind.Locator}");
+
+    [RelayCommand]
+    private Task SelectGpsAsync() => Shell.Current.GoToAsync($"devicescan?kind={DeviceKind.RtkGps}");
+
+    [RelayCommand]
+    private Task ViewMapAsync() => Shell.Current.GoToAsync("//map");
+
+    private void OnFixReceived(object? sender, GnssFix fix)
+    {
+        MainThread.BeginInvokeOnMainThread(() =>
+        {
+            FixStatusLabel = fix.StatusLabel;
+            FixSummary = fix.HasPosition
+                ? $"{fix.Latitude:F8}, {fix.Longitude:F8}  ·  {fix.AltitudeCorrected:F2} m"
+                : "No position";
+            FixAccuracy = $"H ±{fix.Hrms:F3} m · V ±{fix.Vrms:F3} m · {fix.SatellitesUsed} sats · batt {fix.BatteryPercent}%";
+        });
+    }
+
+    private void OnPointSaved(object? sender, LoggedPoint point)
+    {
+        RecentPoints.Insert(0, point);
+        while (RecentPoints.Count > 10)
+            RecentPoints.RemoveAt(RecentPoints.Count - 1);
+        PointCount++;
+    }
+
+    private async void OnPacketIgnoredNoJob(object? sender, EventArgs e)
+    {
+        await Shell.Current.DisplayAlert("No Active Job",
+            "A point was logged on the receiver, but no job is active so it was not saved. Create or select a job first.",
+            "OK");
+    }
+}
--- a/FieldLogger/ViewModels/JobDetailViewModel.cs
+++ b/FieldLogger/ViewModels/JobDetailViewModel.cs
@@ -0,0 +1,59 @@
+using System.Collections.ObjectModel;
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using FieldLogger.Models;
+using FieldLogger.Services.Data;
+
+namespace FieldLogger.ViewModels;
+
+[QueryProperty(nameof(JobId), "jobId")]
+public sealed partial class JobDetailViewModel : ObservableObject
+{
+    private readonly AppDatabase _database;
+
+    [ObservableProperty]
+    private int _jobId;
+
+    [ObservableProperty]
+    private string _jobName = "";
+
+    [ObservableProperty]
+    private int _pointCount;
+
+    public ObservableCollection<LoggedPoint> Points { get; } = new();
+
+    public JobDetailViewModel(AppDatabase database)
+    {
+        _database = database;
+    }
+
+    public async Task RefreshAsync()
+    {
+        var job = await _database.GetJobAsync(JobId);
+        if (job is null)
+            return;
+
+        JobName = job.Name;
+        var points = await _database.GetPointsAsync(JobId);
+        PointCount = points.Count;
+        Points.Clear();
+        foreach (var p in points)
+            Points.Add(p);
+    }
+
+    [RelayCommand]
+    private Task ViewMapAsync() => Shell.Current.GoToAsync($"//map?jobId={JobId}");
+
+    [RelayCommand]
+    private async Task DeletePointAsync(LoggedPoint point)
+    {
+        var confirmed = await Shell.Current.DisplayAlert("Delete Point",
+            $"Delete point #{point.Id} logged {point.TimestampUtc.ToLocalTime():g}?", "Delete", "Cancel");
+        if (!confirmed)
+            return;
+
+        await _database.DeletePointAsync(point.Id);
+        Points.Remove(point);
+        PointCount = Points.Count;
+    }
+}
--- a/FieldLogger/ViewModels/JobsViewModel.cs
+++ b/FieldLogger/ViewModels/JobsViewModel.cs
@@ -0,0 +1,104 @@
+using System.Collections.ObjectModel;
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using FieldLogger.Models;
+using FieldLogger.Services;
+using FieldLogger.Services.Data;
+
+namespace FieldLogger.ViewModels;
+
+public sealed partial class JobListItem : ObservableObject
+{
+    public required Job Job { get; init; }
+
+    [ObservableProperty]
+    private int _pointCount;
+
+    [ObservableProperty]
+    private bool _isActive;
+
+    public string Name => Job.Name;
+    public string CreatedLabel => Job.CreatedUtc.ToLocalTime().ToString("g");
+}
+
+public sealed partial class JobsViewModel : ObservableObject
+{
+    private readonly AppDatabase _database;
+    private readonly SettingsService _settings;
+
+    public ObservableCollection<JobListItem> Jobs { get; } = new();
+
+    [ObservableProperty]
+    private bool _isBusy;
+
+    public JobsViewModel(AppDatabase database, SettingsService settings)
+    {
+        _database = database;
+        _settings = settings;
+    }
+
+    public async Task RefreshAsync()
+    {
+        IsBusy = true;
+        try
+        {
+            var jobs = await _database.GetJobsAsync();
+            var activeId = _settings.ActiveJobId;
+
+            Jobs.Clear();
+            foreach (var job in jobs)
+            {
+                Jobs.Add(new JobListItem
+                {
+                    Job = job,
+                    PointCount = await _database.GetPointCountAsync(job.Id),
+                    IsActive = job.Id == activeId,
+                });
+            }
+        }
+        finally
+        {
+            IsBusy = false;
+        }
+    }
+
+    [RelayCommand]
+    private async Task NewJobAsync()
+    {
+        var name = await Shell.Current.DisplayPromptAsync("New Job", "Job name:",
+            placeholder: $"Job {DateTime.Now:yyyy-MM-dd}");
+        if (string.IsNullOrWhiteSpace(name))
+            return;
+
+        var job = await _database.CreateJobAsync(name.Trim());
+        _settings.ActiveJobId = job.Id;
+        await RefreshAsync();
+    }
+
+    [RelayCommand]
+    private async Task SetActiveAsync(JobListItem item)
+    {
+        _settings.ActiveJobId = item.Job.Id;
+        foreach (var j in Jobs)
+            j.IsActive = j.Job.Id == item.Job.Id;
+        await Task.CompletedTask;
+    }
+
+    [RelayCommand]
+    private Task OpenAsync(JobListItem item)
+        => Shell.Current.GoToAsync($"jobdetail?jobId={item.Job.Id}");
+
+    [RelayCommand]
+    private async Task DeleteAsync(JobListItem item)
+    {
+        var confirmed = await Shell.Current.DisplayAlert("Delete Job",
+            $"Delete \"{item.Job.Name}\" and its {item.PointCount} logged points?", "Delete", "Cancel");
+        if (!confirmed)
+            return;
+
+        await _database.DeleteJobAsync(item.Job.Id);
+        if (_settings.ActiveJobId == item.Job.Id)
+            _settings.ActiveJobId = null;
+        await RefreshAsync();
+    }
+}
--- a/FieldLogger/ViewModels/MapViewModel.cs
+++ b/FieldLogger/ViewModels/MapViewModel.cs
@@ -0,0 +1,53 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using FieldLogger.Models;
+using FieldLogger.Services;
+using FieldLogger.Services.Data;
+
+namespace FieldLogger.ViewModels;
+
+[QueryProperty(nameof(JobId), "jobId")]
+public sealed partial class MapViewModel : ObservableObject
+{
+    private readonly AppDatabase _database;
+    private readonly SettingsService _settings;
+
+    /// <summary>Job to display; 0 means "use the active job".</summary>
+    [ObservableProperty]
+    private int _jobId;
+
+    [ObservableProperty]
+    private string _jobName = "";
+
+    [ObservableProperty]
+    private string _statusText = "";
+
+    public SettingsService Settings => _settings;
+
+    public MapViewModel(AppDatabase database, SettingsService settings)
+    {
+        _database = database;
+        _settings = settings;
+    }
+
+    /// <summary>Loads the points to plot (only points with a valid GNSS position).</summary>
+    public async Task<List<LoggedPoint>> LoadPointsAsync()
+    {
+        var jobId = JobId > 0 ? JobId : _settings.ActiveJobId;
+        if (jobId is null)
+        {
+            JobName = "";
+            StatusText = "No job selected. Create or activate a job to see its points.";
+            return new List<LoggedPoint>();
+        }
+
+        var job = await _database.GetJobAsync(jobId.Value);
+        JobName = job?.Name ?? "";
+
+        var all = await _database.GetPointsAsync(jobId.Value);
+        var plottable = all.Where(p => p.GpsValid).ToList();
+        StatusText = plottable.Count == all.Count
+            ? $"{JobName}: {all.Count} points"
+            : $"{JobName}: {plottable.Count} of {all.Count} points have GPS positions";
+        return plottable;
+    }
+}
--- a/FieldLogger/ViewModels/SettingsViewModel.cs
+++ b/FieldLogger/ViewModels/SettingsViewModel.cs
@@ -0,0 +1,52 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using FieldLogger.Models;
+using FieldLogger.Services;
+
+namespace FieldLogger.ViewModels;
+
+public sealed partial class SettingsViewModel : ObservableObject
+{
+    private readonly DeviceConnectionManager _manager;
+    private readonly SettingsService _settings;
+
+    public DeviceConnectionManager Manager => _manager;
+
+    [ObservableProperty]
+    private string _mapsApiKey = "";
+
+    public string AppVersion => AppInfo.Current.VersionString;
+
+    public SettingsViewModel(DeviceConnectionManager manager, SettingsService settings)
+    {
+        _manager = manager;
+        _settings = settings;
+        MapsApiKey = settings.GoogleMapsApiKey;
+    }
+
+    partial void OnMapsApiKeyChanged(string value) => _settings.GoogleMapsApiKey = value.Trim();
+
+    [RelayCommand]
+    private Task ChangeLocatorAsync() => Shell.Current.GoToAsync($"devicescan?kind={DeviceKind.Locator}");
+
+    [RelayCommand]
+    private Task ChangeGpsAsync() => Shell.Current.GoToAsync($"devicescan?kind={DeviceKind.RtkGps}");
+
+    [RelayCommand]
+    private async Task ForgetLocatorAsync()
+    {
+        if (await ConfirmForgetAsync(_manager.LocatorName ?? "locating receiver"))
+            await _manager.ForgetDeviceAsync(DeviceKind.Locator);
+    }
+
+    [RelayCommand]
+    private async Task ForgetGpsAsync()
+    {
+        if (await ConfirmForgetAsync(_manager.GpsName ?? "RTK GPS receiver"))
+            await _manager.ForgetDeviceAsync(DeviceKind.RtkGps);
+    }
+
+    private static Task<bool> ConfirmForgetAsync(string name) =>
+        Shell.Current.DisplayAlert("Forget Device",
+            $"Forget \"{name}\"? The app will no longer auto-connect to it.", "Forget", "Cancel");
+}
--- a/FieldLogger/Views/DeviceScanPage.xaml
+++ b/FieldLogger/Views/DeviceScanPage.xaml
@@ -0,0 +1,44 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             xmlns:vm="clr-namespace:FieldLogger.ViewModels"
+             xmlns:ble="clr-namespace:FieldLogger.Services.Ble"
+             x:Class="FieldLogger.Views.DeviceScanPage"
+             x:DataType="vm:DeviceScanViewModel"
+             Title="{Binding Title}">
+    <Grid RowDefinitions="Auto,Auto,*" Padding="16" RowSpacing="12">
+
+        <Label Grid.Row="0" Text="{Binding Hint}" FontSize="13" TextColor="Gray" />
+
+        <HorizontalStackLayout Grid.Row="1" Spacing="12">
+            <Button Text="{Binding ScanButtonText}" Command="{Binding ScanCommand}" IsEnabled="{Binding IsScanning, Converter={StaticResource InvertBool}}" />
+            <ActivityIndicator IsRunning="{Binding IsScanning}" VerticalOptions="Center" />
+        </HorizontalStackLayout>
+
+        <CollectionView Grid.Row="2" ItemsSource="{Binding Devices}">
+            <CollectionView.EmptyView>
+                <Label Text="No devices found yet." TextColor="Gray" Margin="8" />
+            </CollectionView.EmptyView>
+            <CollectionView.ItemTemplate>
+                <DataTemplate x:DataType="ble:DiscoveredDevice">
+                    <Border StrokeThickness="0" Background="{AppThemeBinding Light=#F2F2F7, Dark=#1C1C1E}"
+                            StrokeShape="RoundRectangle 10" Padding="12" Margin="0,4">
+                        <Border.GestureRecognizers>
+                            <TapGestureRecognizer
+                                Command="{Binding SelectCommand, Source={RelativeSource AncestorType={x:Type vm:DeviceScanViewModel}}}"
+                                CommandParameter="{Binding .}" />
+                        </Border.GestureRecognizers>
+                        <Grid ColumnDefinitions="*,Auto">
+                            <VerticalStackLayout Spacing="2">
+                                <Label Text="{Binding Name}" FontAttributes="Bold" />
+                                <Label Text="{Binding Id}" FontSize="11" TextColor="Gray" />
+                            </VerticalStackLayout>
+                            <Label Grid.Column="1" VerticalOptions="Center" FontSize="12" TextColor="Gray"
+                                   Text="{Binding Rssi, StringFormat='{0} dBm'}" />
+                        </Grid>
+                    </Border>
+                </DataTemplate>
+            </CollectionView.ItemTemplate>
+        </CollectionView>
+    </Grid>
+</ContentPage>
--- a/FieldLogger/Views/DeviceScanPage.xaml.cs
+++ b/FieldLogger/Views/DeviceScanPage.xaml.cs
@@ -0,0 +1,26 @@
+using FieldLogger.ViewModels;
+
+namespace FieldLogger.Views;
+
+public partial class DeviceScanPage : ContentPage
+{
+    private readonly DeviceScanViewModel _viewModel;
+
+    public DeviceScanPage(DeviceScanViewModel viewModel)
+    {
+        InitializeComponent();
+        BindingContext = _viewModel = viewModel;
+    }
+
+    protected override async void OnAppearing()
+    {
+        base.OnAppearing();
+        await _viewModel.ScanAsync();
+    }
+
+    protected override void OnDisappearing()
+    {
+        _viewModel.StopScan();
+        base.OnDisappearing();
+    }
+}
--- a/FieldLogger/Views/HomePage.xaml
+++ b/FieldLogger/Views/HomePage.xaml
@@ -0,0 +1,108 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             xmlns:vm="clr-namespace:FieldLogger.ViewModels"
+             xmlns:models="clr-namespace:FieldLogger.Models"
+             x:Class="FieldLogger.Views.HomePage"
+             x:DataType="vm:HomeViewModel"
+             Title="Field Logger">
+    <ScrollView>
+        <VerticalStackLayout Padding="16" Spacing="12">
+
+            <!-- Device connection status -->
+            <Border StrokeThickness="0" Background="{AppThemeBinding Light=#F2F2F7, Dark=#1C1C1E}" StrokeShape="RoundRectangle 12" Padding="12">
+                <Grid ColumnDefinitions="16,*,Auto" RowDefinitions="Auto,Auto" RowSpacing="10" ColumnSpacing="10">
+                    <Ellipse Grid.Row="0" Grid.Column="0" WidthRequest="12" HeightRequest="12" VerticalOptions="Center"
+                             Fill="{Binding Manager.LocatorState, Converter={StaticResource StateColor}}" />
+                    <VerticalStackLayout Grid.Row="0" Grid.Column="1" Spacing="0">
+                        <Label Text="{Binding Manager.LocatorName, TargetNullValue='Locating Receiver — not selected'}" FontAttributes="Bold" />
+                        <Label Text="{Binding Manager.LocatorState, Converter={StaticResource StateText}}" FontSize="12" TextColor="Gray" />
+                    </VerticalStackLayout>
+                    <Button Grid.Row="0" Grid.Column="2" Text="Select" FontSize="12" Padding="10,4"
+                            Command="{Binding SelectLocatorCommand}" />
+
+                    <Ellipse Grid.Row="1" Grid.Column="0" WidthRequest="12" HeightRequest="12" VerticalOptions="Center"
+                             Fill="{Binding Manager.GpsState, Converter={StaticResource StateColor}}" />
+                    <VerticalStackLayout Grid.Row="1" Grid.Column="1" Spacing="0">
+                        <Label Text="{Binding Manager.GpsName, TargetNullValue='Maglink RTK GPS — not selected'}" FontAttributes="Bold" />
+                        <Label Text="{Binding Manager.GpsState, Converter={StaticResource StateText}}" FontSize="12" TextColor="Gray" />
+                    </VerticalStackLayout>
+                    <Button Grid.Row="1" Grid.Column="2" Text="Select" FontSize="12" Padding="10,4"
+                            Command="{Binding SelectGpsCommand}" />
+                </Grid>
+            </Border>
+
+            <!-- Live GNSS fix -->
+            <Border StrokeThickness="0" Background="{AppThemeBinding Light=#F2F2F7, Dark=#1C1C1E}" StrokeShape="RoundRectangle 12" Padding="12">
+                <VerticalStackLayout Spacing="4">
+                    <HorizontalStackLayout Spacing="8">
+                        <Label Text="GPS" FontAttributes="Bold" />
+                        <Label Text="{Binding FixStatusLabel}" TextColor="DodgerBlue" FontAttributes="Bold" />
+                    </HorizontalStackLayout>
+                    <Label Text="{Binding FixSummary}" FontFamily="Courier New" FontSize="13" />
+                    <Label Text="{Binding FixAccuracy}" FontSize="12" TextColor="Gray" />
+                </VerticalStackLayout>
+            </Border>
+
+            <!-- Active job -->
+            <Border StrokeThickness="0" Background="{AppThemeBinding Light=#F2F2F7, Dark=#1C1C1E}" StrokeShape="RoundRectangle 12" Padding="12">
+                <VerticalStackLayout Spacing="8">
+                    <Grid ColumnDefinitions="*,Auto">
+                        <VerticalStackLayout Spacing="0">
+                            <Label Text="{Binding ActiveJobName}" FontAttributes="Bold" FontSize="16" />
+                            <Label FontSize="12" TextColor="Gray">
+                                <Label.Text>
+                                    <Binding Path="PointCount" StringFormat="{}{0} points logged" />
+                                </Label.Text>
+                            </Label>
+                        </VerticalStackLayout>
+                        <HorizontalStackLayout Grid.Column="1" Spacing="6">
+                            <Button Text="New Job" FontSize="12" Padding="10,4" Command="{Binding NewJobCommand}" />
+                            <Button Text="Jobs" FontSize="12" Padding="10,4" Command="{Binding SelectJobCommand}" />
+                        </HorizontalStackLayout>
+                    </Grid>
+                    <Label Text="Press the log button on the receiver to capture a point."
+                           FontSize="12" TextColor="Gray" IsVisible="{Binding HasActiveJob}" />
+                </VerticalStackLayout>
+            </Border>
+
+            <!-- Recent points -->
+            <Label Text="Recent Points" FontAttributes="Bold" Margin="4,8,0,0" />
+            <CollectionView ItemsSource="{Binding RecentPoints}" HeightRequest="320">
+                <CollectionView.EmptyView>
+                    <Label Text="No points logged yet." TextColor="Gray" Margin="8" />
+                </CollectionView.EmptyView>
+                <CollectionView.ItemTemplate>
+                    <DataTemplate x:DataType="models:LoggedPoint">
+                        <Border StrokeThickness="0" Background="{AppThemeBinding Light=#FAFAFA, Dark=#242426}"
+                                StrokeShape="RoundRectangle 8" Padding="10" Margin="0,2">
+                            <Grid ColumnDefinitions="*,Auto" RowDefinitions="Auto,Auto">
+                                <Label Grid.Row="0" FontSize="13" FontAttributes="Bold">
+                                    <Label.Text>
+                                        <MultiBinding StringFormat="{}{0} · {1} Hz · depth {2}">
+                                            <Binding Path="Utility" Converter="{StaticResource UtilityName}" />
+                                            <Binding Path="Frequency" />
+                                            <Binding Path="DepthRaw" />
+                                        </MultiBinding>
+                                    </Label.Text>
+                                </Label>
+                                <Label Grid.Row="0" Grid.Column="1" FontSize="12" TextColor="Gray"
+                                       Text="{Binding TimestampUtc, StringFormat='{0:HH:mm:ss}'}" />
+                                <Label Grid.Row="1" Grid.ColumnSpan="2" FontSize="12" TextColor="Gray">
+                                    <Label.Text>
+                                        <MultiBinding StringFormat="{}{0:F7}, {1:F7} · {2}">
+                                            <Binding Path="Latitude" />
+                                            <Binding Path="Longitude" />
+                                            <Binding Path="FixStatus" Converter="{StaticResource FixStatusName}" />
+                                        </MultiBinding>
+                                    </Label.Text>
+                                </Label>
+                            </Grid>
+                        </Border>
+                    </DataTemplate>
+                </CollectionView.ItemTemplate>
+            </CollectionView>
+
+        </VerticalStackLayout>
+    </ScrollView>
+</ContentPage>
--- a/FieldLogger/Views/HomePage.xaml.cs
+++ b/FieldLogger/Views/HomePage.xaml.cs
@@ -0,0 +1,29 @@
+using FieldLogger.ViewModels;
+
+namespace FieldLogger.Views;
+
+public partial class HomePage : ContentPage
+{
+    private readonly HomeViewModel _viewModel;
+    private bool _initialized;
+
+    public HomePage(HomeViewModel viewModel)
+    {
+        InitializeComponent();
+        BindingContext = _viewModel = viewModel;
+    }
+
+    protected override async void OnAppearing()
+    {
+        base.OnAppearing();
+        if (!_initialized)
+        {
+            _initialized = true;
+            await _viewModel.InitializeAsync();
+        }
+        else
+        {
+            await _viewModel.RefreshJobAsync();
+        }
+    }
+}
--- a/FieldLogger/Views/JobDetailPage.xaml
+++ b/FieldLogger/Views/JobDetailPage.xaml
@@ -0,0 +1,77 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             xmlns:vm="clr-namespace:FieldLogger.ViewModels"
+             xmlns:models="clr-namespace:FieldLogger.Models"
+             x:Class="FieldLogger.Views.JobDetailPage"
+             x:DataType="vm:JobDetailViewModel"
+             Title="{Binding JobName}">
+    <ContentPage.ToolbarItems>
+        <ToolbarItem Text="Map" Command="{Binding ViewMapCommand}" />
+    </ContentPage.ToolbarItems>
+
+    <Grid RowDefinitions="Auto,*" Padding="16" RowSpacing="8">
+        <Label Grid.Row="0" FontSize="13" TextColor="Gray"
+               Text="{Binding PointCount, StringFormat='{0} logged points'}" />
+
+        <CollectionView Grid.Row="1" ItemsSource="{Binding Points}">
+            <CollectionView.EmptyView>
+                <Label Text="No points logged for this job yet." TextColor="Gray" Margin="8" />
+            </CollectionView.EmptyView>
+            <CollectionView.ItemTemplate>
+                <DataTemplate x:DataType="models:LoggedPoint">
+                    <Border StrokeThickness="0" Background="{AppThemeBinding Light=#F2F2F7, Dark=#1C1C1E}"
+                            StrokeShape="RoundRectangle 10" Padding="12" Margin="0,4">
+                        <Grid ColumnDefinitions="*,Auto" RowDefinitions="Auto,Auto,Auto,Auto" RowSpacing="2">
+                            <Label Grid.Row="0" FontAttributes="Bold" FontSize="14">
+                                <Label.Text>
+                                    <MultiBinding StringFormat="{}#{0} · {1} · {2} Hz">
+                                        <Binding Path="Id" />
+                                        <Binding Path="Utility" Converter="{StaticResource UtilityName}" />
+                                        <Binding Path="Frequency" />
+                                    </MultiBinding>
+                                </Label.Text>
+                            </Label>
+                            <Label Grid.Row="0" Grid.Column="1" FontSize="12" TextColor="Gray"
+                                   Text="{Binding TimestampUtc, StringFormat='{0:g}'}" />
+
+                            <Label Grid.Row="1" Grid.ColumnSpan="2" FontSize="12">
+                                <Label.Text>
+                                    <MultiBinding StringFormat="Depth {0} · Current {1} · Signal {2} · Gain {3} dB">
+                                        <Binding Path="DepthRaw" />
+                                        <Binding Path="CurrentRaw" />
+                                        <Binding Path="Signal" />
+                                        <Binding Path="GainDb" />
+                                    </MultiBinding>
+                                </Label.Text>
+                            </Label>
+
+                            <Label Grid.Row="2" Grid.ColumnSpan="2" FontSize="12" FontFamily="Courier New">
+                                <Label.Text>
+                                    <MultiBinding StringFormat="{}{0:F8}, {1:F8}">
+                                        <Binding Path="Latitude" />
+                                        <Binding Path="Longitude" />
+                                    </MultiBinding>
+                                </Label.Text>
+                            </Label>
+
+                            <Label Grid.Row="3" FontSize="11" TextColor="Gray">
+                                <Label.Text>
+                                    <MultiBinding StringFormat="{}{0} · H ±{1:F3} m · {2} sats">
+                                        <Binding Path="FixStatus" Converter="{StaticResource FixStatusName}" />
+                                        <Binding Path="Hrms" />
+                                        <Binding Path="SatellitesUsed" />
+                                    </MultiBinding>
+                                </Label.Text>
+                            </Label>
+                            <Button Grid.Row="3" Grid.Column="1" Text="Delete" FontSize="11" Padding="8,2"
+                                    BackgroundColor="Transparent" TextColor="IndianRed"
+                                    Command="{Binding DeletePointCommand, Source={RelativeSource AncestorType={x:Type vm:JobDetailViewModel}}}"
+                                    CommandParameter="{Binding .}" />
+                        </Grid>
+                    </Border>
+                </DataTemplate>
+            </CollectionView.ItemTemplate>
+        </CollectionView>
+    </Grid>
+</ContentPage>
--- a/FieldLogger/Views/JobDetailPage.xaml.cs
+++ b/FieldLogger/Views/JobDetailPage.xaml.cs
@@ -0,0 +1,20 @@
+using FieldLogger.ViewModels;
+
+namespace FieldLogger.Views;
+
+public partial class JobDetailPage : ContentPage
+{
+    private readonly JobDetailViewModel _viewModel;
+
+    public JobDetailPage(JobDetailViewModel viewModel)
+    {
+        InitializeComponent();
+        BindingContext = _viewModel = viewModel;
+    }
+
+    protected override async void OnAppearing()
+    {
+        base.OnAppearing();
+        await _viewModel.RefreshAsync();
+    }
+}
--- a/FieldLogger/Views/JobsPage.xaml
+++ b/FieldLogger/Views/JobsPage.xaml
@@ -0,0 +1,60 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             xmlns:vm="clr-namespace:FieldLogger.ViewModels"
+             x:Class="FieldLogger.Views.JobsPage"
+             x:DataType="vm:JobsViewModel"
+             Title="Jobs">
+    <ContentPage.ToolbarItems>
+        <ToolbarItem Text="New" Command="{Binding NewJobCommand}" />
+    </ContentPage.ToolbarItems>
+
+    <Grid Padding="16">
+        <CollectionView ItemsSource="{Binding Jobs}">
+            <CollectionView.EmptyView>
+                <VerticalStackLayout Spacing="8" VerticalOptions="Center">
+                    <Label Text="No jobs yet." TextColor="Gray" HorizontalOptions="Center" />
+                    <Button Text="Create First Job" Command="{Binding NewJobCommand}" HorizontalOptions="Center" />
+                </VerticalStackLayout>
+            </CollectionView.EmptyView>
+            <CollectionView.ItemTemplate>
+                <DataTemplate x:DataType="vm:JobListItem">
+                    <Border StrokeThickness="0" Background="{AppThemeBinding Light=#F2F2F7, Dark=#1C1C1E}"
+                            StrokeShape="RoundRectangle 10" Padding="12" Margin="0,4">
+                        <Border.GestureRecognizers>
+                            <TapGestureRecognizer
+                                Command="{Binding OpenCommand, Source={RelativeSource AncestorType={x:Type vm:JobsViewModel}}}"
+                                CommandParameter="{Binding .}" />
+                        </Border.GestureRecognizers>
+                        <Grid ColumnDefinitions="*,Auto,Auto" ColumnSpacing="8">
+                            <VerticalStackLayout Spacing="2">
+                                <HorizontalStackLayout Spacing="8">
+                                    <Label Text="{Binding Name}" FontAttributes="Bold" />
+                                    <Border IsVisible="{Binding IsActive}" Background="DodgerBlue"
+                                            StrokeThickness="0" StrokeShape="RoundRectangle 6" Padding="6,1">
+                                        <Label Text="ACTIVE" FontSize="10" TextColor="White" />
+                                    </Border>
+                                </HorizontalStackLayout>
+                                <Label FontSize="12" TextColor="Gray">
+                                    <Label.Text>
+                                        <MultiBinding StringFormat="{}{0} · {1} points">
+                                            <Binding Path="CreatedLabel" />
+                                            <Binding Path="PointCount" />
+                                        </MultiBinding>
+                                    </Label.Text>
+                                </Label>
+                            </VerticalStackLayout>
+                            <Button Grid.Column="1" Text="Set Active" FontSize="12" Padding="10,4" VerticalOptions="Center"
+                                    Command="{Binding SetActiveCommand, Source={RelativeSource AncestorType={x:Type vm:JobsViewModel}}}"
+                                    CommandParameter="{Binding .}" />
+                            <Button Grid.Column="2" Text="✕" FontSize="12" Padding="10,4" VerticalOptions="Center"
+                                    BackgroundColor="IndianRed" TextColor="White"
+                                    Command="{Binding DeleteCommand, Source={RelativeSource AncestorType={x:Type vm:JobsViewModel}}}"
+                                    CommandParameter="{Binding .}" />
+                        </Grid>
+                    </Border>
+                </DataTemplate>
+            </CollectionView.ItemTemplate>
+        </CollectionView>
+    </Grid>
+</ContentPage>
--- a/FieldLogger/Views/JobsPage.xaml.cs
+++ b/FieldLogger/Views/JobsPage.xaml.cs
@@ -0,0 +1,20 @@
+using FieldLogger.ViewModels;
+
+namespace FieldLogger.Views;
+
+public partial class JobsPage : ContentPage
+{
+    private readonly JobsViewModel _viewModel;
+
+    public JobsPage(JobsViewModel viewModel)
+    {
+        InitializeComponent();
+        BindingContext = _viewModel = viewModel;
+    }
+
+    protected override async void OnAppearing()
+    {
+        base.OnAppearing();
+        await _viewModel.RefreshAsync();
+    }
+}
--- a/FieldLogger/Views/MapPage.xaml
+++ b/FieldLogger/Views/MapPage.xaml
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             xmlns:vm="clr-namespace:FieldLogger.ViewModels"
+             x:Class="FieldLogger.Views.MapPage"
+             x:DataType="vm:MapViewModel"
+             Title="Map">
+    <Grid RowDefinitions="Auto,*">
+        <Label Grid.Row="0" Text="{Binding StatusText}" FontSize="12" TextColor="Gray" Padding="12,6" />
+        <!-- Populated in code-behind: native Map control on iOS/Android/macOS, Google Maps WebView on Windows. -->
+        <ContentView Grid.Row="1" x:Name="MapHost" />
+    </Grid>
+</ContentPage>
--- a/FieldLogger/Views/MapPage.xaml.cs
+++ b/FieldLogger/Views/MapPage.xaml.cs
@@ -0,0 +1,151 @@
+using FieldLogger.Models;
+using FieldLogger.ViewModels;
+
+#if WINDOWS
+using System.Text.Json;
+#else
+using Microsoft.Maui.Controls.Maps;
+using Microsoft.Maui.Maps;
+using Map = Microsoft.Maui.Controls.Maps.Map;
+#endif
+
+namespace FieldLogger.Views;
+
+public partial class MapPage : ContentPage
+{
+    private readonly MapViewModel _viewModel;
+
+#if WINDOWS
+    private WebView? _webView;
+    private bool _webMapReady;
+    private List<LoggedPoint>? _pendingPoints;
+#else
+    private Map? _map;
+#endif
+
+    public MapPage(MapViewModel viewModel)
+    {
+        InitializeComponent();
+        BindingContext = _viewModel = viewModel;
+    }
+
+    protected override async void OnAppearing()
+    {
+        base.OnAppearing();
+        await EnsureMapCreatedAsync();
+        var points = await _viewModel.LoadPointsAsync();
+        ShowPoints(points);
+    }
+
+#if WINDOWS
+
+    private async Task EnsureMapCreatedAsync()
+    {
+        if (_webView is not null)
+            return;
+
+        var apiKey = _viewModel.Settings.GoogleMapsApiKey;
+        if (string.IsNullOrWhiteSpace(apiKey))
+        {
+            MapHost.Content = new Label
+            {
+                Text = "Google Maps API key is not set.\nEnter your Maps JavaScript API key on the Settings page.",
+                HorizontalOptions = LayoutOptions.Center,
+                VerticalOptions = LayoutOptions.Center,
+                HorizontalTextAlignment = TextAlignment.Center,
+            };
+            return;
+        }
+
+        using var stream = await FileSystem.OpenAppPackageFileAsync("map.html");
+        using var reader = new StreamReader(stream);
+        var html = (await reader.ReadToEndAsync()).Replace("%%GOOGLE_MAPS_API_KEY%%", apiKey);
+
+        _webView = new WebView { Source = new HtmlWebViewSource { Html = html } };
+        _webView.Navigated += async (_, _) =>
+        {
+            _webMapReady = true;
+            if (_pendingPoints is not null)
+            {
+                var pts = _pendingPoints;
+                _pendingPoints = null;
+                await PushPointsToWebAsync(pts);
+            }
+        };
+        MapHost.Content = _webView;
+    }
+
+    private async void ShowPoints(List<LoggedPoint> points)
+    {
+        if (_webView is null)
+            return;
+        if (!_webMapReady)
+        {
+            _pendingPoints = points;
+            return;
+        }
+        await PushPointsToWebAsync(points);
+    }
+
+    private async Task PushPointsToWebAsync(List<LoggedPoint> points)
+    {
+        var payload = points.Select(p => new
+        {
+            id = p.Id,
+            lat = p.Latitude,
+            lng = p.Longitude,
+            utility = ((UmUtility)p.Utility).ToString(),
+            depth = p.DepthRaw,
+            current = p.CurrentRaw,
+            frequency = p.Frequency,
+            fix = ((GnssFixStatus)p.FixStatus).ToString(),
+            hrms = p.Hrms,
+            time = p.TimestampUtc.ToLocalTime().ToString("g"),
+        });
+        var json = JsonSerializer.Serialize(payload);
+        await _webView!.EvaluateJavaScriptAsync($"setPoints({json})");
+    }
+
+#else
+
+    private Task EnsureMapCreatedAsync()
+    {
+        if (_map is null)
+        {
+            _map = new Map { MapType = MapType.Hybrid, IsShowingUser = false };
+            MapHost.Content = _map;
+        }
+        return Task.CompletedTask;
+    }
+
+    private void ShowPoints(List<LoggedPoint> points)
+    {
+        if (_map is null)
+            return;
+
+        _map.Pins.Clear();
+        foreach (var p in points)
+        {
+            _map.Pins.Add(new Pin
+            {
+                Label = $"#{p.Id} {(UmUtility)p.Utility} · depth {p.DepthRaw}",
+                Address = $"{(GnssFixStatus)p.FixStatus} · ±{p.Hrms:F3} m · {p.TimestampUtc.ToLocalTime():g}",
+                Location = new Location(p.Latitude, p.Longitude),
+            });
+        }
+
+        if (points.Count > 0)
+        {
+            var minLat = points.Min(p => p.Latitude);
+            var maxLat = points.Max(p => p.Latitude);
+            var minLon = points.Min(p => p.Longitude);
+            var maxLon = points.Max(p => p.Longitude);
+            var center = new Location((minLat + maxLat) / 2, (minLon + maxLon) / 2);
+            var spanKm = Math.Max(0.05,
+                Location.CalculateDistance(minLat, minLon, maxLat, maxLon, DistanceUnits.Kilometers) * 0.7);
+            _map.MoveToRegion(MapSpan.FromCenterAndRadius(center, Distance.FromKilometers(spanKm)));
+        }
+    }
+
+#endif
+}
--- a/FieldLogger/Views/SettingsPage.xaml
+++ b/FieldLogger/Views/SettingsPage.xaml
@@ -0,0 +1,64 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             xmlns:vm="clr-namespace:FieldLogger.ViewModels"
+             x:Class="FieldLogger.Views.SettingsPage"
+             x:DataType="vm:SettingsViewModel"
+             Title="Settings">
+    <ScrollView>
+        <VerticalStackLayout Padding="16" Spacing="12">
+
+            <Label Text="Devices" FontAttributes="Bold" FontSize="16" />
+
+            <Border StrokeThickness="0" Background="{AppThemeBinding Light=#F2F2F7, Dark=#1C1C1E}" StrokeShape="RoundRectangle 12" Padding="12">
+                <VerticalStackLayout Spacing="10">
+                    <Grid ColumnDefinitions="16,*,Auto,Auto" ColumnSpacing="8">
+                        <Ellipse WidthRequest="12" HeightRequest="12" VerticalOptions="Center"
+                                 Fill="{Binding Manager.LocatorState, Converter={StaticResource StateColor}}" />
+                        <VerticalStackLayout Grid.Column="1" Spacing="0">
+                            <Label Text="Locating Receiver" FontSize="12" TextColor="Gray" />
+                            <Label Text="{Binding Manager.LocatorName, TargetNullValue='Not selected'}" FontAttributes="Bold" />
+                        </VerticalStackLayout>
+                        <Button Grid.Column="2" Text="Change" FontSize="12" Padding="10,4" Command="{Binding ChangeLocatorCommand}" />
+                        <Button Grid.Column="3" Text="Forget" FontSize="12" Padding="10,4"
+                                BackgroundColor="Transparent" TextColor="IndianRed" Command="{Binding ForgetLocatorCommand}" />
+                    </Grid>
+
+                    <BoxView HeightRequest="1" Color="{AppThemeBinding Light=#E0E0E0, Dark=#333}" />
+
+                    <Grid ColumnDefinitions="16,*,Auto,Auto" ColumnSpacing="8">
+                        <Ellipse WidthRequest="12" HeightRequest="12" VerticalOptions="Center"
+                                 Fill="{Binding Manager.GpsState, Converter={StaticResource StateColor}}" />
+                        <VerticalStackLayout Grid.Column="1" Spacing="0">
+                            <Label Text="Maglink RTK GPS" FontSize="12" TextColor="Gray" />
+                            <Label Text="{Binding Manager.GpsName, TargetNullValue='Not selected'}" FontAttributes="Bold" />
+                        </VerticalStackLayout>
+                        <Button Grid.Column="2" Text="Change" FontSize="12" Padding="10,4" Command="{Binding ChangeGpsCommand}" />
+                        <Button Grid.Column="3" Text="Forget" FontSize="12" Padding="10,4"
+                                BackgroundColor="Transparent" TextColor="IndianRed" Command="{Binding ForgetGpsCommand}" />
+                    </Grid>
+                </VerticalStackLayout>
+            </Border>
+
+            <Label Text="Map" FontAttributes="Bold" FontSize="16" Margin="0,12,0,0" />
+            <Border StrokeThickness="0" Background="{AppThemeBinding Light=#F2F2F7, Dark=#1C1C1E}" StrokeShape="RoundRectangle 12" Padding="12">
+                <VerticalStackLayout Spacing="6">
+                    <Label Text="Google Maps API Key (Windows map view)" FontSize="12" TextColor="Gray" />
+                    <Entry Text="{Binding MapsApiKey}" Placeholder="AIza…" IsPassword="False" />
+                    <Label FontSize="11" TextColor="Gray"
+                           Text="On Android the key is configured in AndroidManifest.xml; iOS and macOS use Apple Maps and need no key." />
+                </VerticalStackLayout>
+            </Border>
+
+            <Label Text="Sync" FontAttributes="Bold" FontSize="16" Margin="0,12,0,0" />
+            <Border StrokeThickness="0" Background="{AppThemeBinding Light=#F2F2F7, Dark=#1C1C1E}" StrokeShape="RoundRectangle 12" Padding="12">
+                <Label Text="MQTT job sync is planned. Data is currently stored locally on this device."
+                       FontSize="12" TextColor="Gray" />
+            </Border>
+
+            <Label Text="{Binding AppVersion, StringFormat='Field Logger v{0}'}"
+                   FontSize="11" TextColor="Gray" HorizontalOptions="Center" Margin="0,20,0,0" />
+
+        </VerticalStackLayout>
+    </ScrollView>
+</ContentPage>
--- a/FieldLogger/Views/SettingsPage.xaml.cs
+++ b/FieldLogger/Views/SettingsPage.xaml.cs
@@ -0,0 +1,12 @@
+using FieldLogger.ViewModels;
+
+namespace FieldLogger.Views;
+
+public partial class SettingsPage : ContentPage
+{
+    public SettingsPage(SettingsViewModel viewModel)
+    {
+        InitializeComponent();
+        BindingContext = viewModel;
+    }
+}