enh: colon fence md

src/lib/utils/marked/colon-fence-extension.ts

@@ -0,0 +1,56 @@
+/**
+ * Marked extension for colon-fence blocks (:::type ... :::)
+ *
+ * Used by newer OpenAI chat models to wrap semantically distinct content:
+ *   :::writing    – reusable prose (letters, articles, docs)
+ *   :::code_execution – code execution output
+ *   :::search_results  – web search results
+ *
+ * The extension is generic and will tokenize any :::<identifier> block.
+ */
+
+function colonFenceTokenizer(this: any, src: string) {
+	// Match :::type at the start of a line, optionally followed by content, then closing :::
+	const match = /^:::([\w-]+)\n([\s\S]*?)(?:\n:::(?:\s*$|\n))/m.exec(src);
+	if (match) {
+		const fenceType = match[1];
+		const text = match[2].trim();
+		const raw = match[0];
+
+		const tokens: any[] = [];
+		this.lexer.blockTokens(text, tokens);
+
+		return {
+			type: 'colonFence',
+			raw,
+			fenceType,
+			text,
+			tokens
+		};
+	}
+}
+
+function colonFenceStart(src: string) {
+	const idx = src.match(/^:::\w/m);
+	return idx ? idx.index! : -1;
+}
+
+function colonFenceRenderer(token: any) {
+	return `<div class="colon-fence colon-fence-${token.fenceType}">${token.text}</div>`;
+}
+
+function colonFenceExtension() {
+	return {
+		name: 'colonFence',
+		level: 'block' as const,
+		start: colonFenceStart,
+		tokenizer: colonFenceTokenizer,
+		renderer: colonFenceRenderer
+	};
+}
+
+export default function (options = {}) {
+	return {
+		extensions: [colonFenceExtension()]
+	};
+}