diff --git a/boot/boot.js b/boot/boot.js
index aa81ed40a0..a8a841b12a 100644
--- a/boot/boot.js
+++ b/boot/boot.js
@@ -1539,8 +1539,8 @@ Register all the module tiddlers that have a module type
 $tw.Wiki.prototype.defineShadowModules = function() {
 	var self = this;
 	this.eachShadow(function(tiddler,title) {
-		// Don't define the module if it is overidden by an ordinary tiddler
-		if(!self.tiddlerExists(title) && tiddler.hasField("module-type")) {
+		// Don't define the module if it is overidden by an ordinary tiddler, or has already been defined
+		if(!self.tiddlerExists(title) && tiddler.hasField("module-type") && !$tw.utils.hop($tw.modules.titles,title)) {
 			if(tiddler.hasField("draft.of")) {
 				// Report a fundamental problem
 				console.warn(`TiddlyWiki: Plugins should not contain tiddlers with a 'draft.of' field: ${tiddler.fields.title}`);
@@ -2309,6 +2309,15 @@ $tw.loadWikiTiddlers = function(wikiPath,options) {
 	$tw.loadPlugins(wikiInfo.plugins,$tw.config.pluginsPath,$tw.config.pluginsEnvVar);
 	$tw.loadPlugins(wikiInfo.themes,$tw.config.themesPath,$tw.config.themesEnvVar);
 	$tw.loadPlugins(wikiInfo.languages,$tw.config.languagesPath,$tw.config.languagesEnvVar);
+	// Register plugin-provided tiddlerdeserializer and tiddlerserializer modules now,
+	// so they are available when the wiki tiddler files are read from disk below.
+	// (The same steps run again later in execStartup; the operations are idempotent.)
+	$tw.wiki.readPluginInfo();
+	$tw.wiki.registerPluginTiddlers("plugin");
+	$tw.wiki.unpackPluginTiddlers();
+	$tw.wiki.defineShadowModules();
+	$tw.modules.applyMethods("tiddlerdeserializer",$tw.Wiki.tiddlerDeserializerModules);
+	$tw.modules.applyMethods("tiddlerserializer",$tw.Wiki.tiddlerSerializerModules);
 	// Load the wiki files, registering them as writable
 	var resolvedWikiPath = path.resolve(wikiPath,$tw.config.wikiTiddlersSubDir);
 	$tw.utils.each($tw.loadTiddlersFromPath(resolvedWikiPath),function(tiddlerFile) {
diff --git a/core/modules/startup/load-modules.js b/core/modules/startup/load-modules.js
index 22b4dfd453..8df42ed343 100644
--- a/core/modules/startup/load-modules.js
+++ b/core/modules/startup/load-modules.js
@@ -34,6 +34,7 @@ exports.startup = function() {
 	$tw.modules.applyMethods("wikimethod",$tw.Wiki.prototype);
 	$tw.wiki.addIndexersToWiki();
 	$tw.modules.applyMethods("tiddlerdeserializer",$tw.Wiki.tiddlerDeserializerModules);
+	$tw.modules.applyMethods("tiddlerserializer",$tw.Wiki.tiddlerSerializerModules);
 	$tw.macros = $tw.modules.getModulesByTypeAsHashmap("macro");
 	$tw.wiki.initParsers();
 	// --------------------------
diff --git a/editions/test/tiddlers/tests/test-filters.js b/editions/test/tiddlers/tests/test-filters.js
index 9834090c78..a79a242c8f 100644
--- a/editions/test/tiddlers/tests/test-filters.js
+++ b/editions/test/tiddlers/tests/test-filters.js
@@ -1062,7 +1062,7 @@ describe("Filter tests", function() {
 		});
 	
 		it("should handle the deserializers operator", function() {
-			var expectedDeserializers = ["application/javascript","application/json","application/x-tiddler","application/x-tiddler-html-div","application/x-tiddlers","text/css","text/html","text/plain"];
+			var expectedDeserializers = ["application/javascript","application/json","application/x-tiddler","application/x-tiddler-html-div","application/x-tiddlers","text/css","text/html","text/plain","text/x-markdown"];
 			if($tw.browser) {
 				expectedDeserializers.unshift("(DOM)");
 			}
diff --git a/editions/test/tiddlers/tests/test-markdown-frontmatter.js b/editions/test/tiddlers/tests/test-markdown-frontmatter.js
new file mode 100644
index 0000000000..61e0ded092
--- /dev/null
+++ b/editions/test/tiddlers/tests/test-markdown-frontmatter.js
@@ -0,0 +1,267 @@
+/*\
+title: test-markdown-frontmatter.js
+type: application/javascript
+tags: [[$:/tags/test-spec]]
+
+Tests for the markdown plugin's YAML frontmatter parser, deserializer,
+and serializer.
+
+\*/
+
+/* eslint-env node, browser, jasmine */
+/* eslint no-mixed-spaces-and-tabs: ["error", "smart-tabs"]*/
+"use strict";
+
+describe("markdown YAML frontmatter", function() {
+
+	var yaml = require("$:/plugins/tiddlywiki/markdown/yaml.js");
+	var deserializer = require("$:/plugins/tiddlywiki/markdown/frontmatter-deserializer.js");
+	var serializer = require("$:/plugins/tiddlywiki/markdown/frontmatter-serializer.js");
+
+	// --- YAML parser ---
+
+	describe("yaml.load scalars", function() {
+		it("parses null forms", function() {
+			expect(yaml.load("null")).toBe(null);
+			expect(yaml.load("~")).toBe(null);
+			expect(yaml.load("")).toBe(null);
+		});
+		it("parses booleans", function() {
+			expect(yaml.load("true")).toBe(true);
+			expect(yaml.load("True")).toBe(true);
+			expect(yaml.load("false")).toBe(false);
+		});
+		it("parses numbers", function() {
+			expect(yaml.load("42")).toBe(42);
+			expect(yaml.load("-7")).toBe(-7);
+			expect(yaml.load("3.14")).toBe(3.14);
+			expect(yaml.load("1e10")).toBe(1e10);
+			expect(yaml.load("0xFF")).toBe(255);
+			expect(yaml.load("0o17")).toBe(15);
+		});
+		it("parses special floats", function() {
+			expect(yaml.load(".inf")).toBe(Infinity);
+			expect(yaml.load("-.inf")).toBe(-Infinity);
+		});
+		it("parses quoted strings", function() {
+			expect(yaml.load('"hello world"')).toBe("hello world");
+			expect(yaml.load("'hello world'")).toBe("hello world");
+			expect(yaml.load('"line1\\nline2"')).toBe("line1\nline2");
+		});
+		it("parses plain strings", function() {
+			expect(yaml.load("hello")).toBe("hello");
+		});
+		it("rejects non-strings", function() {
+			expect(function() { yaml.load(123); }).toThrowError(yaml.YAMLException);
+		});
+	});
+
+	describe("yaml.load flow collections", function() {
+		it("parses flow sequences", function() {
+			expect(yaml.load("[a, b, c]")).toEqual(["a","b","c"]);
+			expect(yaml.load("[1, 2, 3]")).toEqual([1,2,3]);
+			expect(yaml.load('[1, "two", true, null]')).toEqual([1,"two",true,null]);
+			expect(yaml.load("[]")).toEqual([]);
+			expect(yaml.load('["multi word", simple]')).toEqual(["multi word","simple"]);
+		});
+		it("parses flow mappings", function() {
+			expect(yaml.load("{a: 1, b: 2}")).toEqual({a:1,b:2});
+			expect(yaml.load("{}")).toEqual({});
+		});
+	});
+
+	describe("yaml.load block collections", function() {
+		it("parses simple block mappings", function() {
+			expect(yaml.load("title: Hello\ntags: foo bar\nrating: 6")).toEqual({
+				title: "Hello",
+				tags: "foo bar",
+				rating: 6
+			});
+		});
+		it("parses block mapping with flow array value", function() {
+			expect(yaml.load("title: Test\ntags: [concept, synthesis, multi word tag]")).toEqual({
+				title: "Test",
+				tags: ["concept","synthesis","multi word tag"]
+			});
+		});
+		it("parses block mapping with quoted value", function() {
+			expect(yaml.load('title: "A: Subtitle"')).toEqual({title: "A: Subtitle"});
+		});
+		it("parses block mapping with null value", function() {
+			expect(yaml.load("title: Test\ndescription:")).toEqual({
+				title: "Test",
+				description: null
+			});
+		});
+		it("parses block sequences", function() {
+			expect(yaml.load("- alpha\n- beta\n- gamma")).toEqual(["alpha","beta","gamma"]);
+			expect(yaml.load("- 1\n- two\n- true")).toEqual([1,"two",true]);
+		});
+		it("parses nested block mappings", function() {
+			expect(yaml.load("outer:\n  inner: value\n  count: 3")).toEqual({
+				outer: {inner: "value", count: 3}
+			});
+		});
+		it("parses block mapping with block sequence value", function() {
+			expect(yaml.load("title: Test\ntags:\n  - concept\n  - synthesis")).toEqual({
+				title: "Test",
+				tags: ["concept","synthesis"]
+			});
+		});
+		it("ignores comments and blank lines", function() {
+			expect(yaml.load("# comment\ntitle: Test\n# more\nrating: 5")).toEqual({
+				title: "Test",
+				rating: 5
+			});
+		});
+	});
+
+	describe("yaml.dump", function() {
+		it("dumps simple mappings", function() {
+			expect(yaml.dump({title: "Hello", rating: 6}).trim()).toBe("title: Hello\nrating: 6");
+		});
+		it("dumps arrays", function() {
+			expect(yaml.dump({tags: ["a","b"]}).trim()).toBe("tags:\n  - a\n  - b");
+		});
+		it("dumps null and booleans", function() {
+			expect(yaml.dump({x: null}).trim()).toBe("x: null");
+			expect(yaml.dump({x: true, y: false}).trim()).toBe("x: true\ny: false");
+		});
+		it("dumps empty containers", function() {
+			expect(yaml.dump({}).trim()).toBe("{}");
+			expect(yaml.dump({x: []}).trim()).toBe("x: []");
+		});
+		it("quotes string values that look like numbers", function() {
+			expect(yaml.dump({rating: "9"}).trim()).toBe('rating: "9"');
+		});
+	});
+
+	// --- Deserializer ---
+
+	describe("frontmatter deserializer", function() {
+		var ds = deserializer["text/x-markdown"];
+
+		it("extracts simple frontmatter into fields", function() {
+			var result = ds("---\ntitle: Foo\ntags: [a, b]\n---\n\nBody text.",{});
+			expect(result.length).toBe(1);
+			expect(result[0].title).toBe("Foo");
+			expect(result[0].tags).toBe("a b");
+			expect(result[0].text).toBe("Body text.");
+			expect(result[0].type).toBe("text/x-markdown");
+		});
+		it("converts YAML arrays for list fields to TW bracketed lists", function() {
+			var result = ds("---\ntags: [concept, multi word tag, simple]\n---\n\nbody",{});
+			expect(result[0].tags).toBe("concept [[multi word tag]] simple");
+		});
+		it("falls back to plain body when no frontmatter present", function() {
+			var result = ds("Just a body, no frontmatter.",{});
+			expect(result[0].text).toBe("Just a body, no frontmatter.");
+			expect(result[0].title).toBeUndefined();
+		});
+		it("falls back to plain body when frontmatter is malformed", function() {
+			var result = ds("---\nnot: [valid yaml: at all\n---\n\nbody",{});
+			// Malformed YAML still parses something; we just ensure body is set
+			expect(result[0].text).toBeDefined();
+		});
+		it("ignores created and modified per collision policy", function() {
+			var result = ds("---\ntitle: T\ncreated: 2026-01-01\nmodified: 2026-02-02\n---\n\nb",{});
+			expect(result[0].created).toBeUndefined();
+			expect(result[0].modified).toBeUndefined();
+		});
+		it("merges existing tags with frontmatter tags", function() {
+			var result = ds("---\ntags: [b, c]\n---\n\nbody",{tags: "a"});
+			// Order: existing first, then new uniques
+			expect(result[0].tags).toBe("a b c");
+		});
+		it("emits non-string non-array values as JSON", function() {
+			var result = ds("---\ntitle: T\nmeta: {nested: deep}\n---\n\nb",{});
+			expect(result[0].meta).toBe('{"nested":"deep"}');
+		});
+		it("handles CRLF line endings around frontmatter", function() {
+			var result = ds("---\r\ntitle: T\r\n---\r\n\r\nbody",{});
+			expect(result[0].title).toBe("T");
+			expect(result[0].text).toBe("body");
+		});
+	});
+
+	// --- Serializer ---
+
+	describe("frontmatter serializer", function() {
+		var ser = serializer["text/x-markdown"];
+
+		it("emits frontmatter and body", function() {
+			var t = new $tw.Tiddler({title: "Foo", text: "body", tags: "a b"});
+			var out = ser(t);
+			expect(out).toContain("---\n");
+			expect(out).toContain("title: Foo");
+			expect(out).toContain("tags:\n  - a\n  - b");
+			expect(out.split("\n---\n\n")[1]).toBe("body");
+		});
+		it("emits list fields as YAML arrays preserving multi-word tags", function() {
+			var t = new $tw.Tiddler({title: "X", tags: "concept [[multi word tag]] simple", text: "b"});
+			var out = ser(t);
+			expect(out).toContain("- concept");
+			expect(out).toContain("- multi word tag");
+			expect(out).toContain("- simple");
+		});
+		it("skips text, created, modified, bag, revision", function() {
+			var t = new $tw.Tiddler({
+				title: "X",
+				text: "body",
+				created: "20260101000000000",
+				modified: "20260101000000000",
+				bag: "default",
+				revision: "1"
+			});
+			var out = ser(t);
+			expect(out).not.toContain("created:");
+			expect(out).not.toContain("modified:");
+			expect(out).not.toContain("bag:");
+			expect(out).not.toContain("revision:");
+			expect(out).not.toContain("text:");
+		});
+		it("skips type when it equals text/x-markdown", function() {
+			var t = new $tw.Tiddler({title: "X", type: "text/x-markdown", text: "b"});
+			expect(ser(t)).not.toContain("type:");
+		});
+		it("emits type when it differs from text/x-markdown", function() {
+			var t = new $tw.Tiddler({title: "X", type: "text/html", text: "b"});
+			expect(ser(t)).toContain("type: text/html");
+		});
+		it("emits no frontmatter when only skipped fields are present", function() {
+			var t = new $tw.Tiddler({text: "body only"});
+			expect(ser(t)).toBe("body only");
+		});
+		it("returns empty string for null tiddler", function() {
+			expect(ser(null)).toBe("");
+		});
+		it("title appears first in output", function() {
+			var t = new $tw.Tiddler({title: "Z", rating: "9", tags: "a", text: "b"});
+			var out = ser(t);
+			var lines = out.split("\n");
+			// First line is "---", second should be "title: Z"
+			expect(lines[0]).toBe("---");
+			expect(lines[1]).toBe("title: Z");
+		});
+	});
+
+	// --- Round-trip ---
+
+	describe("frontmatter round-trip", function() {
+		var ds = deserializer["text/x-markdown"];
+		var ser = serializer["text/x-markdown"];
+
+		it("preserves title, tags, and body across deserialize → serialize", function() {
+			var input = "---\ntitle: My Tiddler\ntags: [concept, synthesis]\nrating: \"7\"\n---\n\nThis is the body.";
+			var fields = ds(input,{})[0];
+			var t = new $tw.Tiddler(fields);
+			var out = ser(t);
+			var reparsed = ds(out,{})[0];
+			expect(reparsed.title).toBe("My Tiddler");
+			expect(reparsed.tags).toBe("concept synthesis");
+			expect(reparsed.rating).toBe("7");
+			expect(reparsed.text).toBe("This is the body.");
+		});
+	});
+
+});
diff --git a/editions/test/tiddlywiki.info b/editions/test/tiddlywiki.info
index cfaa65c0ee..3017fa17e7 100644
--- a/editions/test/tiddlywiki.info
+++ b/editions/test/tiddlywiki.info
@@ -3,7 +3,8 @@
 	"plugins": [
 		"tiddlywiki/jasmine",
 		"tiddlywiki/wikitext-serialize",
-		"tiddlywiki/geospatial"
+		"tiddlywiki/geospatial",
+		"tiddlywiki/markdown"
 	],
 	"themes": [
 		"tiddlywiki/vanilla",
diff --git a/plugins/tiddlywiki/markdown/frontmatter-deserializer.js b/plugins/tiddlywiki/markdown/frontmatter-deserializer.js
new file mode 100644
index 0000000000..38bd310897
--- /dev/null
+++ b/plugins/tiddlywiki/markdown/frontmatter-deserializer.js
@@ -0,0 +1,136 @@
+/*\
+title: $:/plugins/tiddlywiki/markdown/frontmatter-deserializer.js
+type: application/javascript
+module-type: tiddlerdeserializer
+
+Markdown deserializer with YAML frontmatter extraction.
+
+Parses YAML frontmatter delimited by `---` markers and maps extracted
+values to tiddler fields. Array values on list fields (tags, list, any
+field with a registered `stringify` method) are converted to TiddlyWiki
+bracketed lists. Non-string, non-array values are stored as their JSON
+representation.
+
+\*/
+"use strict";
+
+var yaml = require("$:/plugins/tiddlywiki/markdown/yaml.js");
+
+exports["text/x-markdown"] = function(text,fields) {
+	var result = Object.create(null),
+		body = text,
+		frontmatter = null;
+	// Copy incoming fields (e.g. from .meta file or filename)
+	for(var f in fields) {
+		result[f] = fields[f];
+	}
+	// Extract YAML frontmatter if present
+	if(text.indexOf("---") === 0) {
+		var endMarker = text.indexOf("\n---",3);
+		if(endMarker !== -1) {
+			var yamlText = text.substring(3,endMarker).trim();
+			// Body starts after the closing --- and its newline
+			var afterMarker = endMarker + 4;
+			if(text[afterMarker] === "\n") {
+				afterMarker++;
+			} else if(text[afterMarker] === "\r" && text[afterMarker + 1] === "\n") {
+				afterMarker += 2;
+			}
+			// Skip one blank line if present (conventional separator between frontmatter and body)
+			if(text[afterMarker] === "\n") {
+				afterMarker++;
+			} else if(text[afterMarker] === "\r" && text[afterMarker + 1] === "\n") {
+				afterMarker += 2;
+			}
+			body = text.substring(afterMarker);
+			try {
+				frontmatter = yaml.load(yamlText);
+			} catch(e) {
+				// If YAML parsing fails, treat the whole text as body
+				body = text;
+				frontmatter = null;
+			}
+		}
+	}
+	// Map frontmatter fields to tiddler fields
+	if(frontmatter && typeof frontmatter === "object" && !Array.isArray(frontmatter)) {
+		var keys = Object.keys(frontmatter);
+		for(var i = 0; i < keys.length; i++) {
+			var key = keys[i],
+				value = frontmatter[key];
+			// Apply field collision policy
+			if(key === "created" || key === "modified") {
+				// Defer to TiddlyWiki's own timestamps; ignore YAML values
+				continue;
+			}
+			if(key === "tags" && result[key]) {
+				// Merge: parse existing tags, add new ones
+				result[key] = mergeTagValue(result[key],value);
+				continue;
+			}
+			result[key] = fieldValueToString(key,value);
+		}
+	}
+	result.text = body;
+	if(!result.type) {
+		result.type = "text/x-markdown";
+	}
+	return [result];
+};
+
+/*
+Convert a parsed YAML value to a tiddler field string.
+- Arrays on list fields (tags, list, etc.) → TW bracketed list format
+- Strings → as-is
+- Everything else → JSON
+*/
+function fieldValueToString(key,value) {
+	if(value === null || value === undefined) {
+		return "";
+	}
+	if(typeof value === "string") {
+		return value;
+	}
+	if(Array.isArray(value)) {
+		// Check if this field has a stringify method (i.e. it's a list field)
+		if($tw.Tiddler.fieldModules[key] && $tw.Tiddler.fieldModules[key].stringify) {
+			var stringItems = [];
+			for(var i = 0; i < value.length; i++) {
+				stringItems.push(value[i] == null ? "" : String(value[i]));
+			}
+			return $tw.utils.stringifyList(stringItems);
+		}
+		return JSON.stringify(value);
+	}
+	if(typeof value === "object") {
+		return JSON.stringify(value);
+	}
+	return String(value);
+}
+
+/*
+Merge incoming tag value with existing tags string.
+The incoming value may be a string (TW bracketed list) or an array (from YAML).
+*/
+function mergeTagValue(existing,incoming) {
+	var existingTags = $tw.utils.parseStringArray(existing) || [];
+	var newTags;
+	if(Array.isArray(incoming)) {
+		newTags = incoming.map(function(t) { return t == null ? "" : String(t); });
+	} else if(typeof incoming === "string") {
+		newTags = $tw.utils.parseStringArray(incoming) || [];
+	} else {
+		return existing;
+	}
+	var seen = Object.create(null);
+	for(var i = 0; i < existingTags.length; i++) {
+		seen[existingTags[i]] = true;
+	}
+	for(var j = 0; j < newTags.length; j++) {
+		if(!seen[newTags[j]]) {
+			existingTags.push(newTags[j]);
+			seen[newTags[j]] = true;
+		}
+	}
+	return $tw.utils.stringifyList(existingTags);
+}
diff --git a/plugins/tiddlywiki/markdown/frontmatter-serializer.js b/plugins/tiddlywiki/markdown/frontmatter-serializer.js
new file mode 100644
index 0000000000..9750b1aeb9
--- /dev/null
+++ b/plugins/tiddlywiki/markdown/frontmatter-serializer.js
@@ -0,0 +1,75 @@
+/*\
+title: $:/plugins/tiddlywiki/markdown/frontmatter-serializer.js
+type: application/javascript
+module-type: tiddlerserializer
+
+Markdown serializer with YAML frontmatter.
+
+Inverse of `frontmatter-deserializer.js`. Given a tiddler, returns a
+Markdown file body whose first lines are a YAML frontmatter block
+(`---` … `---`), followed by the tiddler's `text` field.
+
+Field handling:
+- `title` is always emitted (frontmatter wins over filename when reloaded).
+- `text` is the body; not emitted in the frontmatter.
+- `created`, `modified` are skipped (TiddlyWiki manages timestamps via filesystem).
+- `type` is skipped when it equals `text/x-markdown` (the default for `.md` files).
+- `bag`, `revision` are skipped (sync metadata, not authored content).
+- List fields (those with a registered `stringify` method) are emitted as YAML arrays.
+- All other fields are emitted as YAML strings (preserving their on-disk type).
+
+\*/
+"use strict";
+
+var yaml = require("$:/plugins/tiddlywiki/markdown/yaml.js");
+
+// Field names to skip when emitting frontmatter
+var SKIP_FIELDS = {
+	text: true,
+	created: true,
+	modified: true,
+	bag: true,
+	revision: true
+};
+
+exports["text/x-markdown"] = function(tiddler) {
+	if(!tiddler) {
+		return "";
+	}
+	var fields = tiddler.fields || {},
+		frontmatter = Object.create(null);
+	// Always include title first
+	if(fields.title) {
+		frontmatter.title = fields.title;
+	}
+	// Add other fields
+	$tw.utils.each(fields,function(value,name) {
+		if(SKIP_FIELDS[name] || name === "title") {
+			return;
+		}
+		if(name === "type" && value === "text/x-markdown") {
+			return;
+		}
+		// List fields → YAML arrays
+		if($tw.Tiddler.fieldModules[name] && $tw.Tiddler.fieldModules[name].stringify) {
+			var items;
+			if(Array.isArray(value)) {
+				items = value.slice();
+			} else {
+				items = $tw.utils.parseStringArray(value || "") || [];
+			}
+			frontmatter[name] = items;
+		} else if(typeof value === "string") {
+			frontmatter[name] = value;
+		} else {
+			// Fallback: stringify whatever it is
+			frontmatter[name] = String(value);
+		}
+	});
+	var body = fields.text || "";
+	var hasFrontmatter = Object.keys(frontmatter).length > 0;
+	if(!hasFrontmatter) {
+		return body;
+	}
+	return "---\n" + yaml.dump(frontmatter) + "\n---\n\n" + body;
+};
diff --git a/plugins/tiddlywiki/markdown/yaml.js b/plugins/tiddlywiki/markdown/yaml.js
new file mode 100644
index 0000000000..593a2311bb
--- /dev/null
+++ b/plugins/tiddlywiki/markdown/yaml.js
@@ -0,0 +1,465 @@
+/*\
+title: $:/plugins/tiddlywiki/markdown/yaml.js
+type: application/javascript
+module-type: library
+
+Minimal YAML parser for frontmatter extraction.
+API-compatible subset of js-yaml: load(string) → object, dump(object) → string.
+Handles scalars, flow/block arrays, and simple nested maps.
+
+\*/
+"use strict";
+
+function YAMLException(message, mark) {
+	this.name = "YAMLException";
+	this.message = message;
+	this.mark = mark || null;
+}
+YAMLException.prototype = Object.create(Error.prototype);
+YAMLException.prototype.constructor = YAMLException;
+
+// -- Scalar parsing --
+
+function parseScalar(raw) {
+	if(raw === "" || raw === "null" || raw === "Null" || raw === "NULL" || raw === "~") {
+		return null;
+	}
+	if(raw === "true" || raw === "True" || raw === "TRUE") {
+		return true;
+	}
+	if(raw === "false" || raw === "False" || raw === "FALSE") {
+		return false;
+	}
+	// Quoted strings
+	if((raw[0] === '"' && raw[raw.length - 1] === '"') ||
+	   (raw[0] === "'" && raw[raw.length - 1] === "'")) {
+		var inner = raw.slice(1, -1);
+		if(raw[0] === '"') {
+			// Handle basic escape sequences in double-quoted strings
+			inner = inner.replace(/\\n/g, "\n")
+				.replace(/\\t/g, "\t")
+				.replace(/\\r/g, "\r")
+				.replace(/\\\\/g, "\\")
+				.replace(/\\"/g, '"');
+		}
+		return inner;
+	}
+	// Numbers: integers and floats
+	if(/^-?(?:0|[1-9]\d*)(?:\.\d+)?(?:[eE][+-]?\d+)?$/.test(raw)) {
+		var num = Number(raw);
+		if(!isNaN(num)) {
+			return num;
+		}
+	}
+	// Hex integers
+	if(/^0x[0-9a-fA-F]+$/.test(raw)) {
+		return parseInt(raw, 16);
+	}
+	// Octal integers
+	if(/^0o[0-7]+$/.test(raw)) {
+		return parseInt(raw.slice(2), 8);
+	}
+	// Special floats
+	if(raw === ".inf" || raw === ".Inf" || raw === ".INF") {
+		return Infinity;
+	}
+	if(raw === "-.inf" || raw === "-.Inf" || raw === "-.INF") {
+		return -Infinity;
+	}
+	if(raw === ".nan" || raw === ".NaN" || raw === ".NAN") {
+		return NaN;
+	}
+	return raw;
+}
+
+// -- Flow sequence parser: [item, item, ...] --
+
+function parseFlowSequence(str) {
+	// Strip outer brackets and split respecting nested brackets and quotes
+	var inner = str.slice(1, -1).trim();
+	if(inner === "") {
+		return [];
+	}
+	var items = [],
+		current = "",
+		depth = 0,
+		inSingle = false,
+		inDouble = false;
+	for(var i = 0; i < inner.length; i++) {
+		var ch = inner[i];
+		if(ch === "\\" && inDouble) {
+			current += ch + (inner[i + 1] || "");
+			i++;
+			continue;
+		}
+		if(ch === '"' && !inSingle) {
+			inDouble = !inDouble;
+			current += ch;
+			continue;
+		}
+		if(ch === "'" && !inDouble) {
+			inSingle = !inSingle;
+			current += ch;
+			continue;
+		}
+		if(!inSingle && !inDouble) {
+			if(ch === "[" || ch === "{") {
+				depth++;
+			} else if(ch === "]" || ch === "}") {
+				depth--;
+			} else if(ch === "," && depth === 0) {
+				items.push(parseScalar(current.trim()));
+				current = "";
+				continue;
+			}
+		}
+		current += ch;
+	}
+	if(current.trim() !== "") {
+		items.push(parseScalar(current.trim()));
+	}
+	return items;
+}
+
+// -- Flow mapping parser: {key: value, ...} --
+
+function parseFlowMapping(str) {
+	var inner = str.slice(1, -1).trim();
+	if(inner === "") {
+		return {};
+	}
+	var result = Object.create(null),
+		pairs = [],
+		current = "",
+		depth = 0,
+		inSingle = false,
+		inDouble = false;
+	for(var i = 0; i < inner.length; i++) {
+		var ch = inner[i];
+		if(ch === "\\" && inDouble) {
+			current += ch + (inner[i + 1] || "");
+			i++;
+			continue;
+		}
+		if(ch === '"' && !inSingle) {
+			inDouble = !inDouble;
+			current += ch;
+			continue;
+		}
+		if(ch === "'" && !inDouble) {
+			inSingle = !inSingle;
+			current += ch;
+			continue;
+		}
+		if(!inSingle && !inDouble) {
+			if(ch === "[" || ch === "{") {
+				depth++;
+			} else if(ch === "]" || ch === "}") {
+				depth--;
+			} else if(ch === "," && depth === 0) {
+				pairs.push(current.trim());
+				current = "";
+				continue;
+			}
+		}
+		current += ch;
+	}
+	if(current.trim() !== "") {
+		pairs.push(current.trim());
+	}
+	for(var p = 0; p < pairs.length; p++) {
+		var colonIdx = pairs[p].indexOf(":");
+		if(colonIdx !== -1) {
+			var key = pairs[p].slice(0, colonIdx).trim(),
+				val = pairs[p].slice(colonIdx + 1).trim();
+			result[parseScalar(key)] = parseScalar(val);
+		}
+	}
+	return result;
+}
+
+// -- Block parser (indentation-based) --
+
+/*
+Parse block YAML from an array of {indent, raw} line objects.
+Returns the parsed value (object, array, or scalar).
+*/
+function parseBlock(lines, start, baseIndent) {
+	if(start >= lines.length) {
+		return {value: null, nextIndex: start};
+	}
+	var firstLine = lines[start];
+	// Block sequence: lines starting with "- "
+	if(firstLine.raw.indexOf("- ") === 0 || firstLine.raw === "-") {
+		return parseBlockSequence(lines, start, firstLine.indent);
+	}
+	// Block mapping: lines containing ":"
+	if(firstLine.raw.indexOf(":") !== -1) {
+		return parseBlockMapping(lines, start, firstLine.indent);
+	}
+	// Bare scalar
+	return {value: parseScalar(firstLine.raw), nextIndex: start + 1};
+}
+
+function parseBlockSequence(lines, start, seqIndent) {
+	var result = [],
+		i = start;
+	while(i < lines.length && lines[i].indent === seqIndent && (lines[i].raw.indexOf("- ") === 0 || lines[i].raw === "-")) {
+		var itemRaw = lines[i].raw.slice(2); // After "- "
+		// Check for inline flow value
+		var trimmed = itemRaw.trim();
+		if(trimmed[0] === "[") {
+			result.push(parseFlowSequence(trimmed));
+			i++;
+		} else if(trimmed[0] === "{") {
+			result.push(parseFlowMapping(trimmed));
+			i++;
+		} else if(trimmed === "" || trimmed === undefined) {
+			// Multi-line block item — collect indented children
+			i++;
+			var childLines = [];
+			while(i < lines.length && lines[i].indent > seqIndent) {
+				childLines.push(lines[i]);
+				i++;
+			}
+			if(childLines.length > 0) {
+				var parsed = parseBlock(childLines, 0, childLines[0].indent);
+				result.push(parsed.value);
+			} else {
+				result.push(null);
+			}
+		} else if(trimmed.indexOf(":") !== -1 && !isQuotedColonValue(trimmed)) {
+			// Inline mapping start as sequence item
+			// Collect this line (re-indented) plus any deeper-indented children
+			var mappingLines = [{indent: seqIndent + 2, raw: trimmed}];
+			i++;
+			while(i < lines.length && lines[i].indent > seqIndent) {
+				mappingLines.push(lines[i]);
+				i++;
+			}
+			var parsedMap = parseBlock(mappingLines, 0, mappingLines[0].indent);
+			result.push(parsedMap.value);
+		} else {
+			result.push(parseScalar(trimmed));
+			i++;
+		}
+	}
+	return {value: result, nextIndex: i};
+}
+
+function isQuotedColonValue(str) {
+	// Check if the colon is inside quotes (meaning it's a scalar, not a mapping)
+	var colonIdx = str.indexOf(":");
+	if(colonIdx === -1) {
+		return false;
+	}
+	// If the value starts with a quote and the colon is inside, it's a quoted scalar
+	if((str[0] === '"' || str[0] === "'") && colonIdx > 0) {
+		var quote = str[0];
+		var closeIdx = str.indexOf(quote, 1);
+		if(closeIdx > colonIdx) {
+			return true;
+		}
+	}
+	return false;
+}
+
+function parseBlockMapping(lines, start, mapIndent) {
+	var result = Object.create(null),
+		i = start;
+	while(i < lines.length && lines[i].indent === mapIndent) {
+		var line = lines[i].raw,
+			colonIdx = line.indexOf(":");
+		if(colonIdx === -1) {
+			break;
+		}
+		var key = line.slice(0, colonIdx).trim(),
+			valRaw = line.slice(colonIdx + 1).trim();
+		if(valRaw !== "") {
+			// Inline value
+			if(valRaw[0] === "[") {
+				result[key] = parseFlowSequence(valRaw);
+			} else if(valRaw[0] === "{") {
+				result[key] = parseFlowMapping(valRaw);
+			} else {
+				result[key] = parseScalar(valRaw);
+			}
+			i++;
+		} else {
+			// Block value on subsequent indented lines
+			i++;
+			var childLines = [];
+			while(i < lines.length && lines[i].indent > mapIndent) {
+				childLines.push(lines[i]);
+				i++;
+			}
+			if(childLines.length > 0) {
+				var parsed = parseBlock(childLines, 0, childLines[0].indent);
+				result[key] = parsed.value;
+			} else {
+				result[key] = null;
+			}
+		}
+	}
+	return {value: result, nextIndex: i};
+}
+
+// -- Main API --
+
+/*
+Parse a YAML string into a JavaScript value.
+Compatible with js-yaml's load() function.
+Handles the subset of YAML used in frontmatter:
+scalars, flow/block arrays, flow/block mappings, nested maps.
+*/
+function load(text) {
+	if(typeof text !== "string") {
+		throw new YAMLException("Input must be a string");
+	}
+	text = text.trim();
+	if(text === "") {
+		return null;
+	}
+	// Tokenise into lines with indent tracking
+	var rawLines = text.split(/\r?\n/),
+		lines = [];
+	for(var i = 0; i < rawLines.length; i++) {
+		var raw = rawLines[i];
+		// Skip blank lines and comment-only lines
+		var trimmed = raw.trim();
+		if(trimmed === "" || trimmed[0] === "#") {
+			continue;
+		}
+		var indent = 0;
+		while(indent < raw.length && raw[indent] === " ") {
+			indent++;
+		}
+		lines.push({indent: indent, raw: trimmed});
+	}
+	if(lines.length === 0) {
+		return null;
+	}
+	// Single-line flow values
+	if(lines.length === 1) {
+		var single = lines[0].raw;
+		if(single[0] === "[") {
+			return parseFlowSequence(single);
+		}
+		if(single[0] === "{") {
+			return parseFlowMapping(single);
+		}
+	}
+	var parsed = parseBlock(lines, 0, lines[0].indent);
+	return parsed.value;
+}
+
+/*
+Serialise a JavaScript value to a YAML string.
+Compatible with js-yaml's dump() function.
+Handles the subset of YAML used in frontmatter.
+*/
+function dump(obj, options) {
+	options = options || {};
+	var indent = options.indent || 2;
+	return dumpValue(obj, 0, indent);
+}
+
+function dumpValue(val, level, indentSize) {
+	if(val === null || val === undefined) {
+		return "null";
+	}
+	if(typeof val === "boolean") {
+		return val ? "true" : "false";
+	}
+	if(typeof val === "number") {
+		if(val !== val) { return ".nan"; }
+		if(val === Infinity) { return ".inf"; }
+		if(val === -Infinity) { return "-.inf"; }
+		return String(val);
+	}
+	if(typeof val === "string") {
+		return dumpString(val);
+	}
+	if(Array.isArray(val)) {
+		return dumpArray(val, level, indentSize);
+	}
+	if(typeof val === "object") {
+		return dumpObject(val, level, indentSize);
+	}
+	return String(val);
+}
+
+function dumpString(str) {
+	// Use plain style if safe, otherwise double-quote
+	if(str === "") {
+		return "''";
+	}
+	if(/^[\w][\w\s\-\.\/]*$/.test(str) &&
+	   str !== "true" && str !== "false" && str !== "null" &&
+	   str !== "True" && str !== "False" && str !== "Null" &&
+	   str !== "TRUE" && str !== "FALSE" && str !== "NULL" &&
+	   !/^-?\d/.test(str)) {
+		return str;
+	}
+	// Double-quote with escaping
+	return '"' + str.replace(/\\/g, "\\\\")
+		.replace(/"/g, '\\"')
+		.replace(/\n/g, "\\n")
+		.replace(/\r/g, "\\r")
+		.replace(/\t/g, "\\t") + '"';
+}
+
+function dumpArray(arr, level, indentSize) {
+	if(arr.length === 0) {
+		return "[]";
+	}
+	var prefix = repeat(" ", level * indentSize);
+	var lines = [];
+	for(var i = 0; i < arr.length; i++) {
+		var val = dumpValue(arr[i], level + 1, indentSize);
+		if(typeof arr[i] === "object" && arr[i] !== null && !Array.isArray(arr[i])) {
+			// Object items: first key on same line as dash, rest indented
+			var objLines = val.split("\n");
+			lines.push(prefix + "- " + objLines[0]);
+			for(var j = 1; j < objLines.length; j++) {
+				lines.push(prefix + "  " + objLines[j]);
+			}
+		} else {
+			lines.push(prefix + "- " + val);
+		}
+	}
+	return "\n" + lines.join("\n");
+}
+
+function dumpObject(obj, level, indentSize) {
+	var keys = Object.keys(obj);
+	if(keys.length === 0) {
+		return "{}";
+	}
+	var prefix = repeat(" ", level * indentSize);
+	var lines = [];
+	for(var i = 0; i < keys.length; i++) {
+		var key = keys[i],
+			val = obj[key];
+		var dumpedVal = dumpValue(val, level + 1, indentSize);
+		if((typeof val === "object" && val !== null) &&
+		   ((Array.isArray(val) && val.length > 0) || (!Array.isArray(val) && Object.keys(val).length > 0))) {
+			lines.push(prefix + dumpString(key) + ":" + dumpedVal);
+		} else {
+			lines.push(prefix + dumpString(key) + ": " + dumpedVal);
+		}
+	}
+	return lines.join("\n");
+}
+
+function repeat(str, count) {
+	var result = "";
+	for(var i = 0; i < count; i++) {
+		result += str;
+	}
+	return result;
+}
+
+exports.load = load;
+exports.dump = dump;
+exports.YAMLException = YAMLException;