fix: list Linux browser web apps and profiles as separate apps

AGENTS.md

@@ -74,7 +74,11 @@ single-configuration integration to `default` and keeps only the first.
 - macOS reports one Now Playing app and has no per-app volume. Do not emulate either.
 - Linux has no system-wide current player; the one that started playing last stands in. MPRIS volume is
   the player's own, so a player without a `Volume` property gets no slider. An app id is the bus name
-  after `org.mpris.MediaPlayer2.` without a `.instance...` suffix, so every instance is one app.
+  after `org.mpris.MediaPlayer2.` without a `.instance...` suffix, so every instance is one app, unless its
+  process was launched with a window class or profile of its own (a web app, a second Firefox profile):
+  that instance becomes `<app>@<variant>`, read once from the bus owner's `/proc/<pid>/cmdline`
+  (`LaunchVariant`), and is named by the `.desktop` file of that class if there is one. A plain launch
+  never gets a variant, so plain app ids, and the widgets bound to them, never change.
 - Sound devices are an `IAudioDevices` behind `IMediaPlatform.AudioDevices`: Core Audio on Windows and
   macOS, `pactl --format=json` on Linux (it ships with PulseAudio and `pipewire-pulse`, run with
   `LC_NUMERIC=C` because some locales break its JSON). Only Windows has communication defaults; elsewhere

README.md

@@ -27,6 +27,8 @@ Spotify, Firefox, Chromium-based browsers, VLC, Rhythmbox, Elisa and most others
 `mpv-mpris` plugin). Nothing has to be installed. Macro Deck has to run inside your desktop session to
 reach the session bus; otherwise the integration shows an issue with a **Try again** button. Linux has no
 system-wide "current" player, so *Any app* treats the player that started playing last as current.
+A browser started as a web app (Linux Mint's Web Apps, Peppermint's Ice) or with a profile of its own is
+listed as an app of its own, named after the web app; all other windows of that browser are one app.
 
 ## Usage
 
@@ -162,8 +164,9 @@ Everything runs on your computer. The plugin sends nothing about you or your med
 - **Linux:** players are read over the D-Bus session bus with the bundled
   [Tmds.DBus.Protocol](https://github.com/tmds/Tmds.DBus) library (MIT). A player that reports its cover
   as a web address (Spotify does) has the cover downloaded from there, as the desktop's own media controls
-  do. App icons come from the apps' `.desktop` files and the icon theme. Sound devices are read and
-  switched by running `pactl`.
+  do. App icons come from the apps' `.desktop` files and the icon theme. A browser's launch arguments are
+  read from `/proc` to tell its web apps and profiles apart. Sound devices are read and switched by
+  running `pactl`.
 
 ## Development
 

src/SystemMedia/Platform/Linux/DesktopEntries.cs

@@ -50,9 +50,12 @@ private static bool IsFileName(string name) =>
 		}
 	}
 
-	// Desktop actions carry Icon= keys of their own.
-	internal static string? IconNameOf(IEnumerable<string> desktopFileLines)
+	internal string? NameOf(string desktopEntry) => IsFileName(desktopEntry) ? ValueOf(desktopEntry, "Name") : null;
+
+	// Desktop actions carry keys of their own.
+	internal static string? ValueOf(IEnumerable<string> desktopFileLines, string key)
 	{
+		var prefix = key + "=";
 		var inEntry = false;
 		foreach (var raw in desktopFileLines)
 		{
@@ -63,9 +66,9 @@ private static bool IsFileName(string name) =>
 				continue;
 			}
 
-			if (inEntry && line.StartsWith("Icon=", StringComparison.Ordinal) && line.Length > "Icon=".Length)
+			if (inEntry && line.StartsWith(prefix, StringComparison.Ordinal) && line.Length > prefix.Length)
 			{
-				return line["Icon=".Length..].Trim();
+				return line[prefix.Length..].Trim();
 			}
 		}
 
@@ -74,7 +77,7 @@ private static bool IsFileName(string name) =>
 
 	private string? FindIcon(string? desktopEntry, string appId)
 	{
-		var iconName = IconNameOf(desktopEntry ?? appId) ?? IconNameOf(appId.ToLowerInvariant()) ?? appId.ToLowerInvariant();
+		var iconName = ValueOf(desktopEntry ?? appId, "Icon") ?? ValueOf(appId.ToLowerInvariant(), "Icon") ?? appId.ToLowerInvariant();
 		if (Path.IsPathRooted(iconName))
 		{
 			return iconName.EndsWith(".png", StringComparison.OrdinalIgnoreCase) && File.Exists(iconName) ? iconName : null;
@@ -86,7 +89,7 @@ private static bool IsFileName(string name) =>
 		return candidates.FirstOrDefault(File.Exists);
 	}
 
-	private string? IconNameOf(string desktopEntry)
+	private string? ValueOf(string desktopEntry, string key)
 	{
 		var fileName = desktopEntry.EndsWith(".desktop", StringComparison.Ordinal) ? desktopEntry : desktopEntry + ".desktop";
 		foreach (var directory in dataDirectories)
@@ -99,7 +102,7 @@ private static bool IsFileName(string name) =>
 
 			try
 			{
-				return IconNameOf(File.ReadLines(path));
+				return ValueOf(File.ReadLines(path), key);
 			}
 			catch (Exception exception) when (exception is IOException or UnauthorizedAccessException)
 			{

src/SystemMedia/Platform/Linux/LaunchVariant.cs

@@ -0,0 +1,56 @@
+namespace SystemMedia.Platform.Linux;
+
+// The MPRIS instance id changes with every start, so a web app or second profile is named by its launch arguments.
+internal static class LaunchVariant
+{
+	// The variant ends up in the app id, its stored name and the instance list.
+	private const int MaxLength = 100;
+
+	internal static string? Of(IReadOnlyList<string> arguments, string appId)
+	{
+		var variant = Value(arguments, "class") ?? Value(arguments, "name") ?? Last(Value(arguments, "profile"))
+			?? Value(arguments, "P") ?? Last(Value(arguments, "user-data-dir"));
+		return variant is { Length: > 0 and <= MaxLength } && !variant.Any(char.IsControl) &&
+			!string.Equals(variant, appId, StringComparison.OrdinalIgnoreCase) ? variant : null;
+	}
+
+	internal static IReadOnlyList<string> ReadArguments(uint processId)
+	{
+		try
+		{
+			return File.ReadAllText($"/proc/{processId}/cmdline").TrimEnd('\0').Split('\0');
+		}
+		catch (Exception exception) when (exception is IOException or UnauthorizedAccessException)
+		{
+			return [];
+		}
+	}
+
+	// Firefox takes options with one dash or two, followed by the value or joined to it with "=".
+	private static string? Value(IReadOnlyList<string> arguments, string option)
+	{
+		for (var index = 1; index < arguments.Count; index++)
+		{
+			var argument = arguments[index];
+			var name = argument.StartsWith("--", StringComparison.Ordinal) ? argument[2..] : argument.StartsWith('-') ? argument[1..] : null;
+			if (name is null)
+			{
+				continue;
+			}
+
+			if (string.Equals(name, option, StringComparison.Ordinal))
+			{
+				return index + 1 < arguments.Count && !arguments[index + 1].StartsWith('-') ? arguments[index + 1].Trim() : null;
+			}
+
+			if (name.StartsWith(option + "=", StringComparison.Ordinal))
+			{
+				return name[(option.Length + 1)..].Trim();
+			}
+		}
+
+		return null;
+	}
+
+	private static string? Last(string? path) => path is null ? null : Path.GetFileName(path.TrimEnd('/'));
+}

src/SystemMedia/Platform/Linux/LinuxMediaPlatform.cs

@@ -348,14 +348,31 @@ private async Task PollAsync()
 		Replace(current);
 	}
 
-	private static async Task<MprisPlayer> ReadRootAsync(MprisBus bus, string busName)
+	private async Task<MprisPlayer> ReadRootAsync(MprisBus bus, string busName)
 	{
 		var root = await bus.GetAllAsync(busName, MprisBus.RootInterface).WaitAsync(_callTimeout);
-		return new MprisPlayer(
+		var player = new MprisPlayer(
 			busName,
 			root.GetValueOrDefault("Identity") as string,
 			root.GetValueOrDefault("DesktopEntry") as string,
 			new Dictionary<string, object?>());
+		return player.IsInstance && await LaunchVariantOfAsync(bus, player) is { } variant
+			? player.LaunchedAs(variant, _desktop.NameOf(variant))
+			: player;
+	}
+
+	// A sandboxed player (Flatpak) is owned by its bus proxy, whose arguments name no variant.
+	private static async Task<string?> LaunchVariantOfAsync(MprisBus bus, MprisPlayer player)
+	{
+		try
+		{
+			var processId = await bus.GetProcessIdAsync(player.BusName).WaitAsync(_callTimeout);
+			return LaunchVariant.Of(LaunchVariant.ReadArguments(processId), player.AppId);
+		}
+		catch (Exception exception) when (IsCallFailure(exception))
+		{
+			return null;
+		}
 	}
 
 	private void Replace(Dictionary<string, MprisPlayer> current)

src/SystemMedia/Platform/Linux/MprisBus.cs

@@ -45,6 +45,14 @@ internal async Task<IReadOnlyList<string>> ListPlayersAsync() =>
 			null);
 	}
 
+	internal Task<uint> GetProcessIdAsync(string busName)
+	{
+		using var writer = _connection.GetMessageWriter();
+		writer.WriteMethodCallHeader("org.freedesktop.DBus", "/org/freedesktop/DBus", "org.freedesktop.DBus", "GetConnectionUnixProcessID", "s", MessageFlags.None);
+		writer.WriteString(busName);
+		return _connection.CallMethodAsync(writer.CreateMessage(), static (message, _) => message.GetBodyReader().ReadUInt32(), null);
+	}
+
 	internal Task CallAsync(string busName, string member)
 	{
 		using var writer = _connection.GetMessageWriter();

src/SystemMedia/Platform/Linux/MprisPlayer.cs

@@ -7,7 +7,12 @@ internal sealed record MprisPlayer(string BusName, string? Identity, string? Des
 {
 	private const string NoTrack = "/org/mpris/MediaPlayer2/TrackList/NoTrack";
 
-	internal string AppId => AppIdOf(BusName);
+	internal string? Variant { get; private init; }
+
+	// "@" never appears in a bus name, so a variant cannot collide with another player.
+	internal string AppId => Variant is null ? AppIdOf(BusName) : $"{AppIdOf(BusName)}@{Variant}";
+
+	internal bool IsInstance => BusName.Contains(".instance", StringComparison.Ordinal);
 
 	internal bool IsPlaying => string.Equals(Text("PlaybackStatus"), "Playing", StringComparison.Ordinal);
 
@@ -33,6 +38,14 @@ internal static string AppIdOf(string busName)
 		return instance > 0 ? name[..instance] : name;
 	}
 
+	// A web app's own .desktop file is named after its window class and gives it its name and icon.
+	internal MprisPlayer LaunchedAs(string variant, string? desktopName) => this with
+	{
+		Variant = variant,
+		Identity = desktopName ?? $"{Identity ?? AppIdOf(BusName)} ({variant})",
+		DesktopEntry = desktopName is null ? DesktopEntry : variant,
+	};
+
 	internal MediaSnapshot ToSnapshot(DateTimeOffset readAt)
 	{
 		var length = Number(Metadata, "mpris:length");

tests/SystemMedia.Tests/Linux/DesktopEntriesTests.cs

@@ -60,6 +60,18 @@ public void A_desktop_entry_that_is_a_path_is_ignored()
 	public void An_app_without_any_icon_has_none() =>
 		Assert.That(new DesktopEntries([_root]).IconPath("unknown", "unknown"), Is.Null);
 
+	[Test]
+	public void A_web_app_is_named_by_its_own_desktop_file()
+	{
+		Write("applications/WebApp-SpotifyWeb3778.desktop", "[Desktop Entry]\nName=Spotify\n\n[Desktop Action new]\nName=Other\n");
+		Write("outside.desktop", "[Desktop Entry]\nName=Outside\n");
+		var entries = new DesktopEntries([_root]);
+
+		Assert.That(entries.NameOf("WebApp-SpotifyWeb3778"), Is.EqualTo("Spotify"));
+		Assert.That(entries.NameOf("../outside"), Is.Null);
+		Assert.That(entries.NameOf("unknown"), Is.Null);
+	}
+
 	[Test]
 	public void The_data_directories_follow_the_xdg_defaults()
 	{

tests/SystemMedia.Tests/Linux/LaunchVariantTests.cs

@@ -0,0 +1,45 @@
+using NUnit.Framework;
+using SystemMedia.Platform.Linux;
+
+namespace SystemMedia.Tests.Linux;
+
+[TestFixture]
+public sealed class LaunchVariantTests
+{
+	[Test]
+	public void A_linux_mint_web_app_is_named_by_its_window_class() =>
+		Assert.That(Variant(
+			"/usr/lib/firefox/firefox", "--class", "WebApp-SpotifyWeb3778", "--name", "WebApp-SpotifyWeb3778",
+			"--profile", "/home/user/.local/share/ice/firefox/SpotifyWeb3778", "--no-remote", "https://open.spotify.com/"),
+			Is.EqualTo("WebApp-SpotifyWeb3778"));
+
+	[TestCase("--profile", "/home/me/.mozilla/firefox/abcd.work/", ExpectedResult = "abcd.work")]
+	[TestCase("-profile", "/home/me/.mozilla/firefox/abcd.work", ExpectedResult = "abcd.work")]
+	[TestCase("--profile=/home/me/.mozilla/firefox/abcd.work", null, ExpectedResult = "abcd.work")]
+	[TestCase("-P", "work", ExpectedResult = "work")]
+	[TestCase("--user-data-dir=/home/me/.config/chromium-work", null, ExpectedResult = "chromium-work")]
+	public string? A_second_profile_is_named_by_its_profile(string option, string? value) =>
+		Variant(value is null ? ["/usr/lib/firefox/firefox", option] : ["/usr/lib/firefox/firefox", option, value]);
+
+	[Test]
+	public void A_plain_launch_is_no_variant()
+	{
+		Assert.That(Variant("/usr/lib/firefox/firefox", "https://example.com"), Is.Null);
+		Assert.That(Variant("/usr/lib/firefox/firefox", "-P", "--new-window"), Is.Null, "-P alone opens the profile manager");
+		Assert.That(Variant(), Is.Null);
+	}
+
+	[Test]
+	public void A_class_that_is_the_app_itself_is_no_variant() =>
+		Assert.That(Variant("/usr/lib/firefox/firefox", "--class", "Firefox"), Is.Null);
+
+	[Test]
+	public void An_oversized_or_unprintable_variant_is_ignored()
+	{
+		Assert.That(Variant("/usr/lib/firefox/firefox", "--class", new string('x', 101)), Is.Null);
+		Assert.That(Variant("/usr/lib/firefox/firefox", "--class", "Web\u001b[31mApp"), Is.Null);
+		Assert.That(Variant("/usr/lib/firefox/firefox", "--class", new string('x', 100)), Is.Not.Null);
+	}
+
+	private static string? Variant(params string[] arguments) => LaunchVariant.Of(arguments, "firefox");
+}

tests/SystemMedia.Tests/Linux/MprisPlayerTests.cs

@@ -16,6 +16,25 @@ public sealed class MprisPlayerTests
 	public void Every_instance_of_a_player_belongs_to_one_app(string busName, string appId) =>
 		Assert.That(MprisPlayer.AppIdOf(busName), Is.EqualTo(appId));
 
+	[Test]
+	public void An_instance_launched_as_a_variant_is_an_app_of_its_own()
+	{
+		var firefox = new MprisPlayer("org.mpris.MediaPlayer2.firefox.instance_1_918", "Mozilla Firefox", "firefox", new Dictionary<string, object?>());
+
+		var webApp = firefox.LaunchedAs("WebApp-SpotifyWeb3778", "Spotify");
+		var profile = firefox.LaunchedAs("work", desktopName: null);
+
+		Assert.That(firefox.IsInstance, Is.True);
+		Assert.That(firefox.AppId, Is.EqualTo("firefox"));
+		Assert.That(webApp.AppId, Is.EqualTo("firefox@WebApp-SpotifyWeb3778"));
+		Assert.That(webApp.Identity, Is.EqualTo("Spotify"));
+		Assert.That(webApp.DesktopEntry, Is.EqualTo("WebApp-SpotifyWeb3778"));
+		Assert.That(profile.AppId, Is.EqualTo("firefox@work"));
+		Assert.That(profile.Identity, Is.EqualTo("Mozilla Firefox (work)"));
+		Assert.That(profile.DesktopEntry, Is.EqualTo("firefox"));
+		Assert.That(Player(new()).IsInstance, Is.False);
+	}
+
 	[Test]
 	public void A_playing_track_becomes_a_snapshot_with_its_timeline()
 	{