diff --git a/src/RioJoy.Core/Profiles/ConfigStore.cs b/src/RioJoy.Core/Profiles/ConfigStore.cs
index 54cabb7..ff1d88b 100644
--- a/src/RioJoy.Core/Profiles/ConfigStore.cs
+++ b/src/RioJoy.Core/Profiles/ConfigStore.cs
@@ -52,4 +52,48 @@ public static class ConfigStore
         if (string.IsNullOrWhiteSpace(path)) throw new ArgumentException("Value cannot be null or whitespace.", nameof(path));
         return File.Exists(path) ? Deserialize(File.ReadAllText(path)) : new AppConfig();
     }
+
+    /// <summary>
+    /// Deserialize a single-profile document (the shape shipped in a repo's
+    /// <c>profiles/*.json</c>) with the same serializer settings as the config.
+    /// </summary>
+    public static RioProfile DeserializeProfile(string json)
+    {
+        if (string.IsNullOrWhiteSpace(json)) throw new ArgumentException("Value cannot be null or whitespace.", nameof(json));
+        return JsonConvert.DeserializeObject<RioProfile>(json, Options)
+               ?? throw new JsonSerializationException("Profile JSON deserialized to null.");
+    }
+
+    /// <summary>
+    /// Merge the single-profile file at <paramref name="profilePath"/> into the
+    /// config at <paramref name="configPath"/> (created with defaults if absent).
+    /// A profile with the same name (case-insensitive, the
+    /// <see cref="AppConfig.FindProfile"/> convention) is replaced in place;
+    /// otherwise the profile is appended. All other config content is preserved.
+    /// </summary>
+    public static ProfileImportResult ImportProfile(string configPath, string profilePath)
+    {
+        string profileJson = File.ReadAllText(profilePath);
+        RioProfile profile = DeserializeProfile(profileJson);
+        // Name keys the merge, and RioProfile defaults it to "Unnamed" — so a
+        // document that never states one must be rejected, not merged under the
+        // class default.
+        if (Newtonsoft.Json.Linq.JObject.Parse(profileJson).Value<string>("Name") is not { Length: > 0 })
+            throw new JsonSerializationException($"Profile file '{profilePath}' has no Name.");
+
+        AppConfig config = Load(configPath);
+        int existing = config.Profiles.FindIndex(
+            p => string.Equals(p.Name, profile.Name, StringComparison.OrdinalIgnoreCase));
+        bool replaced = existing >= 0;
+        if (replaced)
+            config.Profiles[existing] = profile;
+        else
+            config.Profiles.Add(profile);
+
+        Save(config, configPath);
+        return new ProfileImportResult(profile.Name!, replaced);
+    }
 }
+
+/// <summary>Outcome of <see cref="ConfigStore.ImportProfile"/>.</summary>
+public sealed record ProfileImportResult(string Name, bool Replaced);
diff --git a/src/RioJoy.Tray/Program.cs b/src/RioJoy.Tray/Program.cs
index 9079431..5fa5ae4 100644
--- a/src/RioJoy.Tray/Program.cs
+++ b/src/RioJoy.Tray/Program.cs
@@ -1,3 +1,5 @@
+using RioJoy.Core.Profiles;
+
 namespace RioJoy.Tray;
 
 internal static class Program
@@ -12,18 +14,63 @@ internal static class Program
     /// Entry point. RIOJoy runs as a background tray application with no main
     /// window: an ApplicationContext owns the NotifyIcon and the runtime, so the
     /// message loop stays alive while the only UI is the tray icon and its menu.
+    ///
+    /// <para><c>--import-profile &lt;profile.json&gt;</c> merges a single-profile
+    /// document (a repo's <c>profiles/*.json</c>) into this user's config and
+    /// exits without starting the tray. Output goes to stdout/stderr, which a
+    /// GUI-subsystem exe only delivers when redirected — check the exit code
+    /// (0 ok, 1 failed, 2 usage, 3 tray running) when scripting it.</para>
     /// </summary>
     [STAThread]
-    private static void Main()
+    private static int Main(string[] args)
     {
+        if (args.Length >= 1 && string.Equals(args[0], "--import-profile", StringComparison.OrdinalIgnoreCase))
+            return ImportProfile(args);
+
         using var instance = new Mutex(initiallyOwned: true, SingleInstanceMutex, out bool createdNew);
         if (!createdNew)
-            return; // another RIOJoy is already running in this session
+            return 0; // another RIOJoy is already running in this session
 
         // net48 has no source-generated ApplicationConfiguration.Initialize();
         // do the equivalent setup directly.
         Application.EnableVisualStyles();
         Application.SetCompatibleTextRenderingDefault(false);
         Application.Run(new TrayApplicationContext());
+        return 0;
+    }
+
+    private static int ImportProfile(string[] args)
+    {
+        if (args.Length != 2)
+        {
+            Console.Error.WriteLine("usage: RioJoy.Tray --import-profile <profile.json>");
+            return 2;
+        }
+
+        // A running tray holds the config in memory and rewrites it on its own
+        // saves, which would silently discard this import — refuse instead.
+        // (OpenExisting + catch rather than TryOpenExisting: net40 lacks the Try form.)
+        try
+        {
+            using Mutex running = Mutex.OpenExisting(SingleInstanceMutex);
+            Console.Error.WriteLine("RIOJoy is running in this session - quit it from the tray menu, import, then relaunch.");
+            return 3;
+        }
+        catch (WaitHandleCannotBeOpenedException)
+        {
+            // not running — proceed
+        }
+
+        try
+        {
+            ProfileImportResult result = ConfigStore.ImportProfile(TrayApplicationContext.ConfigPath, args[1]);
+            Console.WriteLine($"{(result.Replaced ? "Replaced" : "Added")} profile '{result.Name}' in {TrayApplicationContext.ConfigPath}");
+            return 0;
+        }
+        catch (Exception ex)
+        {
+            Console.Error.WriteLine($"import failed: {ex.Message}");
+            return 1;
+        }
     }
 }
diff --git a/src/RioJoy.Tray/TrayApplicationContext.cs b/src/RioJoy.Tray/TrayApplicationContext.cs
index deca113..cd04b55 100644
--- a/src/RioJoy.Tray/TrayApplicationContext.cs
+++ b/src/RioJoy.Tray/TrayApplicationContext.cs
@@ -17,7 +17,8 @@ namespace RioJoy.Tray;
 /// </summary>
 internal sealed class TrayApplicationContext : ApplicationContext
 {
-    private static readonly string ConfigPath =
+    // Internal so Program's --import-profile writes the same store the tray reads.
+    internal static readonly string ConfigPath =
         Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "RIOJoy", "config.json");
 
     private static readonly TimeSpan PollInterval = TimeSpan.FromSeconds(1);
diff --git a/tests/RioJoy.Core.Tests/Profiles/ConfigStoreTests.cs b/tests/RioJoy.Core.Tests/Profiles/ConfigStoreTests.cs
index 8348948..bd9104e 100644
--- a/tests/RioJoy.Core.Tests/Profiles/ConfigStoreTests.cs
+++ b/tests/RioJoy.Core.Tests/Profiles/ConfigStoreTests.cs
@@ -138,6 +138,87 @@ public class ConfigStoreTests
         Assert.Equal(File.ReadAllBytes(shipped), File.ReadAllBytes(reference));
     }
 
+    [Fact]
+    public void ImportProfile_ShippedDescentFile_IntoFreshConfig()
+    {
+        string configPath = Path.Combine(Path.GetTempPath(), $"riojoy-import-{Guid.NewGuid():N}", "config.json");
+        try
+        {
+            string shipped = Path.Combine(TestRepo.Root(), "profiles", "descent-d1x.json");
+            ProfileImportResult result = ConfigStore.ImportProfile(configPath, shipped);
+
+            Assert.Equal("Descent", result.Name);
+            Assert.False(result.Replaced);
+
+            RioProfile p = Assert.Single(ConfigStore.Load(configPath).Profiles);
+            Assert.Equal("Descent", p.Name);
+            // The routing must survive the import round-trip intact — this is the
+            // exact payload a cabinet/bench install writes.
+            Assert.NotNull(p.AxisRouting);
+            Assert.Equal(new AxisRoute { Target = PadTarget.RightThumbY, Mode = AxisOutputMode.UnipolarPositive }, p.AxisRouting!.Z);
+        }
+        finally
+        {
+            string? dir = Path.GetDirectoryName(configPath);
+            if (dir is not null && Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public void ImportProfile_ReplacesSameName_PreservesEverythingElse()
+    {
+        string configPath = Path.Combine(Path.GetTempPath(), $"riojoy-import-{Guid.NewGuid():N}", "config.json");
+        try
+        {
+            ConfigStore.Save(new AppConfig
+            {
+                DefaultRioComPort = "COM7",
+                NeutralProfileName = "Desktop",
+                Profiles =
+                {
+                    new RioProfile { Name = "Desktop" },
+                    new RioProfile { Name = "descent", PlasmaGreeting = "STALE" }, // case-insensitive match
+                },
+            }, configPath);
+
+            string shipped = Path.Combine(TestRepo.Root(), "profiles", "descent-d1x.json");
+            ProfileImportResult result = ConfigStore.ImportProfile(configPath, shipped);
+            Assert.True(result.Replaced);
+
+            AppConfig back = ConfigStore.Load(configPath);
+            Assert.Equal("COM7", back.DefaultRioComPort);       // untouched settings survive
+            Assert.Equal("Desktop", back.NeutralProfileName);
+            Assert.Equal(2, back.Profiles.Count);               // replaced in place, not appended
+            RioProfile descent = Assert.IsType<RioProfile>(back.FindProfile("Descent"));
+            Assert.Equal("DESCENT", descent.PlasmaGreeting);    // stale profile fully overwritten
+        }
+        finally
+        {
+            string? dir = Path.GetDirectoryName(configPath);
+            if (dir is not null && Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public void ImportProfile_NamelessProfile_Throws()
+    {
+        string dir = Path.Combine(Path.GetTempPath(), $"riojoy-import-{Guid.NewGuid():N}");
+        Directory.CreateDirectory(dir);
+        try
+        {
+            string profilePath = Path.Combine(dir, "nameless.json");
+            File.WriteAllText(profilePath, "{\"PlasmaGreeting\":\"X\"}");
+            Assert.Throws<Newtonsoft.Json.JsonSerializationException>(
+                () => ConfigStore.ImportProfile(Path.Combine(dir, "config.json"), profilePath));
+        }
+        finally
+        {
+            Directory.Delete(dir, recursive: true);
+        }
+    }
+
     [Fact]
     public void Load_MissingFile_ReturnsDefaults()
     {