webui: Fix parsing non-LaTeX occurrencies of \( or \) (#17810)

* fix: Improve latex protection logic to prevent turning non-latex `\(` into `$`

* chore: update webui build output

Author: allozaur

tools/server/public/index.html.gz

@@ -303,6 +303,27 @@ $$\n\\pi_n(\\mathbb{S}^3) = \\begin{cases}
 		expect(output).toBe(input); // Code blocks prevent misinterpretation
 	});
 
+	test('preserves backslash parentheses in code blocks (GitHub issue)', () => {
+		const input = '```python\nfoo = "\\(bar\\)"\n```';
+		const output = preprocessLaTeX(input);
+
+		expect(output).toBe(input); // Code blocks should not have LaTeX conversion applied
+	});
+
+	test('preserves backslash brackets in code blocks', () => {
+		const input = '```python\nfoo = "\\[bar\\]"\n```';
+		const output = preprocessLaTeX(input);
+
+		expect(output).toBe(input); // Code blocks should not have LaTeX conversion applied
+	});
+
+	test('preserves backslash parentheses in inline code', () => {
+		const input = 'Use `foo = "\\(bar\\)"` in your code.';
+		const output = preprocessLaTeX(input);
+
+		expect(output).toBe(input);
+	});
+
 	test('escape backslash in mchem ce', () => {
 		const input = 'mchem ce:\n$\\ce{2H2(g) + O2(g) -> 2H2O(l)}$';
 		const output = preprocessLaTeX(input);

tools/server/webui/src/lib/utils/latex-protection.test.ts

@@ -226,19 +226,16 @@ export function preprocessLaTeX(content: string): string {
 		return expr;
 	});
 
-	// Step 5: Restore code blocks
-	content = content.replace(/<<CODE_BLOCK_(\d+)>>/g, (_, index) => {
-		return codeBlocks[parseInt(index)];
-	});
-
-	// Step 6: Apply additional escaping functions (brackets and mhchem)
+	// Step 5: Apply additional escaping functions (brackets and mhchem)
+	// This must happen BEFORE restoring code blocks to avoid affecting code content
 	content = escapeBrackets(content);
 
 	if (doEscapeMhchem && (content.includes('\\ce{') || content.includes('\\pu{'))) {
 		content = escapeMhchem(content);
 	}
 
-	// Final pass: Convert \(...\) → $...$, \[...\] → $$...$$
+	// Step 6: Convert remaining \(...\) → $...$, \[...\] → $$...$$
+	// This must happen BEFORE restoring code blocks to avoid affecting code content
 	content = content
 		// Using the look‑behind pattern `(?<!\\)` we skip matches
 		// that are preceded by a backslash, e.g.
@@ -248,12 +245,18 @@ export function preprocessLaTeX(content: string): string {
 			// Using the look‑behind pattern `(?<!\\)` we skip matches
 			// that are preceded by a backslash, e.g. `\\[4pt]`.
 			/(?<!\\)\\\[([\s\S]*?)\\\]/g, // display, see also PR #16599
-			(_, prefix: string, content: string) => {
-				return `${prefix}$$${content}$$`;
+			(_, content: string) => {
+				return `$$${content}$$`;
 			}
 		);
 
-	// Step 7: Restore blockquote markers
+	// Step 7: Restore code blocks
+	// This happens AFTER all LaTeX conversions to preserve code content
+	content = content.replace(/<<CODE_BLOCK_(\d+)>>/g, (_, index) => {
+		return codeBlocks[parseInt(index)];
+	});
+
+	// Step 8: Restore blockquote markers
 	if (blockquoteMarkers.size > 0) {
 		const finalLines = content.split('\n');
 		const restoredLines = finalLines.map((line, index) => {