refac: disable single tilde

src/lib/components/chat/Messages/Markdown.svelte

@@ -5,6 +5,7 @@
 
 	import markedExtension from '$lib/utils/marked/extension';
 	import markedKatexExtension from '$lib/utils/marked/katex-extension';
+	import { disableSingleTilde } from '$lib/utils/marked/strikethrough-extension';
 	import { mentionExtension } from '$lib/utils/marked/mention-extension';
 
 	import MarkdownTokens from './Markdown/MarkdownTokens.svelte';
@@ -38,6 +39,7 @@
 
 	marked.use(markedKatexExtension(options));
 	marked.use(markedExtension(options));
+	marked.use(disableSingleTilde);
 	marked.use({
 		extensions: [mentionExtension({ triggerChar: '@' }), mentionExtension({ triggerChar: '#' })]
 	});

src/lib/utils/marked/strikethrough-extension.ts

@@ -0,0 +1,29 @@
+export const disableSingleTilde = {
+	tokenizer: {
+		del(src) {
+			// 1. First check for the REAL strikethrough: ~~text~~
+			const doubleMatch = /^~~(?=\S)([\s\S]*?\S)~~/.exec(src);
+			if (doubleMatch) {
+				return {
+					type: 'del',
+					raw: doubleMatch[0],
+					text: doubleMatch[1],
+					tokens: this.lexer.inlineTokens(doubleMatch[1])
+				};
+			}
+
+			// 2. Check for single-tilde: ~text~
+			const singleMatch = /^~(?=\S)([\s\S]*?\S)~/.exec(src);
+			if (singleMatch) {
+				// return a plain-text token, NOT del
+				return {
+					type: 'text',
+					raw: singleMatch[0],
+					text: singleMatch[0] // include both tildes as literal text
+				};
+			}
+
+			return false;
+		}
+	}
+};