Put MXP images and sounds in their T= directory, and keep a short extended colour's components

CHANGELOG.md

@@ -6,6 +6,15 @@ All notable changes to `MarkupString`, `MarkupString.Ansi`, `MarkupString.Html`,
 The format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/), and the project
 follows [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Fixed
+
+- MXP `IMAGE` and `SOUND` put the file in the `T=` type's directory under the base address, as the MXP
+  specification says: `<IMAGE map.png URL=https://h/img/ T=maps>` is `https://h/img/maps/map.png`.
+- An SGR extended colour with too few components (`38;2;40`) no longer reads what is left as codes of their own,
+  so it does not set a black background.
+
 ## 2.26.0 — 2026-11-06
 
 ### Added

MarkupString.Ansi/Decoding/VtPlugins.cs

@@ -155,6 +155,9 @@ public static AnsiStyle Apply(AnsiStyle style, in CsiSequence sequence)
 		}
 		else if (first + 2 >= sequence.Count)
 		{
+			// Too few components: they are still the colour's, not codes of their own (38;2;40 does not
+			// set a black background).
+			i = sequence.Count - 1;
 			return null;
 		}
 

MarkupString.Mxp/Decoding/MxpDecoding.cs

@@ -699,7 +699,7 @@ private void Image(ParsedTag tag)
 	{
 		var file = tag.Get("FNAME", 0);
 		if (string.IsNullOrEmpty(file)) return;
-		var source = Address(tag.Get("URL"), file);
+		var source = Address(tag.Get("URL"), tag.Get("T"), file);
 		var (width, widthCells) = Size(tag.Get("W"));
 		var (height, heightCells) = Size(tag.Get("H"));
 		var align = Enum.TryParse<ImageAlign>(tag.Get("ALIGN"), ignoreCase: true, out var parsed) ? parsed : (ImageAlign?)null;
@@ -758,13 +758,21 @@ private void Sound(ParsedTag tag)
 			? l < 0 ? SoundMarkup.Forever : l
 			: null;
 		var continues = music && tag.Get("C") == "1";
-		Context.Point(new SoundMarkup(Address(tag.Get("U"), file), channel, volume, repeats, continues));
+		Context.Point(new SoundMarkup(Address(tag.Get("U"), tag.Get("T"), file), channel, volume, repeats, continues));
 	}
 
-	private static string Address(string? directory, string file)
+	/// <summary>
+	/// Where a picture or sound is: the file under the base address, in the type's directory when there is one
+	/// ("the classname is appended to the URL, along with the name of the file itself"), or the file as it is
+	/// when there is no base or the file is already absolute.
+	/// </summary>
+	private static string Address(string? directory, string? type, string file)
 	{
 		if (string.IsNullOrEmpty(directory) || Uri.TryCreate(file, UriKind.Absolute, out _)) return file;
-		return directory.EndsWith('/') ? directory + file : directory + "/" + file;
+		var address = directory.EndsWith('/') ? directory : directory + "/";
+		var kind = type?.Trim().Trim('/');
+		if (!string.IsNullOrEmpty(kind)) address += kind + "/";
+		return address + file;
 	}
 
 	// ── Helpers ─────────────────────────────────────────────────────────────────

MarkupString.Tests/Decoding/MxpDecodingTests.cs

@@ -224,6 +224,22 @@ public async Task WhatThisPackageWrites_ReadsBack()
 		await Assert.That(spans[^1].Style.Interaction).IsEqualTo(new Interaction(InteractionKind.Command, "look") { Hint = "Look" });
 	}
 
+	[Test]
+	public async Task Image_TypeIsADirectoryUnderTheUrl()
+	{
+		var (lines, _, _) = Decode("\e[1z<IMAGE map.png URL=\"https://example.test/img/\" T=maps>\n\e[1z<IMAGE map.png URL=https://example.test/img T=/maps/>\n\e[1z<SOUND door.wav U=https://example.test/ T=doors>\n");
+		await Assert.That(Markups(lines[0]).OfType<ImageMarkup>().Single().Source).IsEqualTo("https://example.test/img/maps/map.png");
+		await Assert.That(Markups(lines[1]).OfType<ImageMarkup>().Single().Source).IsEqualTo("https://example.test/img/maps/map.png");
+		await Assert.That(Markups(lines[2]).OfType<SoundMarkup>().Single().Source).IsEqualTo("https://example.test/doors/door.wav");
+	}
+
+	[Test]
+	public async Task Image_TypeWithoutUrlLeavesTheName()
+	{
+		var (lines, _, _) = Decode("\e[1z<IMAGE https://example.test/x.png T=maps>\n");
+		await Assert.That(Markups(lines[0]).OfType<ImageMarkup>().Single().Source).IsEqualTo("https://example.test/x.png");
+	}
+
 	[Test]
 	public async Task Image_InCells_IsDrawnOverTheLines()
 	{

MarkupString.Tests/Decoding/VtDecodingTests.cs

@@ -90,6 +90,14 @@ public async Task Sgr_StandardColour()
 		await Assert.That(span.Style.Has(TextAttributes.Bold)).IsTrue();
 	}
 
+	[Test]
+	public async Task Sgr_TruncatedTrueColour_SetsNothing()
+	{
+		var span = Only("\e[31;38;2;40mx\n");
+		await Assert.That(span.Style.Foreground).IsEqualTo(new RgbColor(170, 0, 0));
+		await Assert.That(span.Style.Background).IsNull();
+	}
+
 	[Test]
 	public async Task Sgr_TrueColour_SemicolonsAndColons()
 	{

docs/decoding.md

@@ -134,7 +134,8 @@ The decoder acts on none of these. Refuse a clipboard write unless the player al
 | `53`, `55` | Overline on, off |
 | `58` | Underline colour: its parameters are read and dropped |
 
-Any other code is ignored. An extended colour out of range leaves the colour as it was. The style
+Any other code is ignored. An extended colour out of range leaves the colour as it was, and so does one
+with too few components, whose components are not read as codes of their own. The style
 is written under the `VtPens.Style` pen as an `AnsiMarkup`.
 
 ### `ControlsPlugin`
@@ -584,8 +585,8 @@ What the tags become:
 | `B`, `I`, `U`, `S`, `H`, `COLOR`, `FONT` | An `AnsiMarkup`. SGR inside an MXP colour wins, as in an MXP client. |
 | `A href hint` | A URL link, when `DecoderOptions.Links` allows the address |
 | `SEND href hint prompt` | A command link. With several commands (`a\|b`) or `PROMPT`, a `CommandMenuMarkup` as well. With no `href`, or `&text;` in it, the command is the tag's text. |
-| `IMAGE fname url w h align` | An `ImageMarkup`. Sized in cells (`W=4c H=2c`), it is drawn over the cells the server leaves for it. |
-| `SOUND`, `MUSIC` | `SoundMarkup` or `SoundStopMarkup` points |
+| `IMAGE fname url t w h align` | An `ImageMarkup` at `url`, then the `t` directory, then `fname`. Sized in cells (`W=4c H=2c`), it is drawn over the cells the server leaves for it. |
+| `SOUND`, `MUSIC` | `SoundMarkup` or `SoundStopMarkup` points, at `u`, then `t`, then the file |
 | `FRAME`, `DEST` | A `PaneMarkup` over the text in `DEST`, titled from its `FRAME` |
 | `VAR name` | A `VariableMarkup` over its text, and a `VariableEvent` |
 | `EXPIRE`, `RELOCATE`, `USER`, `PASSWORD` | Their points |