From e1124d170d10cd7e8f5d9ec091fc3888f2c8567b Mon Sep 17 00:00:00 2001
From: Anish Sarkar <104695310+AnishSarkar22@users.noreply.github.com>
Date: Sat, 14 Feb 2026 14:29:16 +0530
Subject: [PATCH] feat: update LaTeX delimiter conversion for Streamdown
 compatibility

---
 surfsense_web/components/markdown-viewer.tsx | 64 ++++++++++++--------
 1 file changed, 39 insertions(+), 25 deletions(-)

diff --git a/surfsense_web/components/markdown-viewer.tsx b/surfsense_web/components/markdown-viewer.tsx
index bf5310303..81310e751 100644
--- a/surfsense_web/components/markdown-viewer.tsx
+++ b/surfsense_web/components/markdown-viewer.tsx
@@ -29,45 +29,59 @@ function stripOuterMarkdownFence(content: string): string {
 }
 
 /**
- * Convert all LaTeX delimiter styles to the dollar-sign syntax
- * that remark-math understands, and normalise edge-cases that
- * commonly appear in LLM-generated markdown.
+ * Convert all LaTeX delimiter styles to the double-dollar syntax
+ * that Streamdown's @streamdown/math plugin understands.
  *
- *   \[...\]                              → $$ ... $$  (block / display math)
- *   \(...\)                              → $ ... $    (inline math)
- *   \begin{equation}...\end{equation}    → $$ ... $$  (block math)
- *   \begin{displaymath}...\end{displaymath} → $$ ... $$ (block math)
- *   \begin{math}...\end{math}            → $ ... $    (inline math)
- *   same-line $$…$$                       → $ ... $    (inline math — display math
- *                                                        can't live inside table cells)
- *   `$$ … $$`                             → $$ … $$    (strip wrapping backtick code)
- *   `$ … $`                               → $ … $      (strip wrapping backtick code)
+ * Streamdown math conventions (different from remark-math!):
+ *   $$...$$  on the SAME line     → inline math
+ *   $$\n...\n$$  on SEPARATE lines → block (display) math
+ *
+ * Conversions performed:
+ *   \[...\]                              → $$\n ... \n$$  (block math)
+ *   \(...\)                              → $$...$$        (inline math, same line)
+ *   \begin{equation}...\end{equation}    → $$\n ... \n$$  (block math)
+ *   \begin{displaymath}...\end{displaymath} → $$\n ... \n$$ (block math)
+ *   \begin{math}...\end{math}            → $$...$$        (inline math, same line)
+ *   `$$ … $$`                             → $$ … $$       (strip wrapping backtick code)
+ *   `$ … $`                               → $ … $         (strip wrapping backtick code)
+ *   $...$                                 → $$...$$        (normalise single-$ to double-$$)
  */
 function convertLatexDelimiters(content: string): string {
-	// 1. Block math: \[...\] → $$...$$
-	content = content.replace(/\\\[([\s\S]*?)\\\]/g, (_, inner) => `$$${inner}$$`);
-	// 2. Inline math: \(...\) → $...$
-	content = content.replace(/\\\(([\s\S]*?)\\\)/g, (_, inner) => `$${inner}$`);
-	// 3. Block: \begin{equation}...\end{equation} → $$...$$
+	// 1. Block math: \[...\] → $$\n...\n$$ (display math on separate lines)
+	content = content.replace(
+		/\\\[([\s\S]*?)\\\]/g,
+		(_, inner) => `\n$$\n${inner.trim()}\n$$\n`,
+	);
+	// 2. Inline math: \(...\) → $$...$$ (inline math on same line)
+	content = content.replace(
+		/\\\(([\s\S]*?)\\\)/g,
+		(_, inner) => `$$${inner.trim()}$$`,
+	);
+	// 3. Block: \begin{equation}...\end{equation} → $$\n...\n$$
 	content = content.replace(
 		/\\begin\{equation\}([\s\S]*?)\\end\{equation\}/g,
-		(_, inner) => `$$${inner}$$`,
+		(_, inner) => `\n$$\n${inner.trim()}\n$$\n`,
 	);
-	// 4. Block: \begin{displaymath}...\end{displaymath} → $$...$$
+	// 4. Block: \begin{displaymath}...\end{displaymath} → $$\n...\n$$
 	content = content.replace(
 		/\\begin\{displaymath\}([\s\S]*?)\\end\{displaymath\}/g,
-		(_, inner) => `$$${inner}$$`,
+		(_, inner) => `\n$$\n${inner.trim()}\n$$\n`,
 	);
-	// 5. Inline: \begin{math}...\end{math} → $...$
+	// 5. Inline: \begin{math}...\end{math} → $$...$$
 	content = content.replace(
 		/\\begin\{math\}([\s\S]*?)\\end\{math\}/g,
-		(_, inner) => `$${inner}$`,
+		(_, inner) => `$$${inner.trim()}$$`,
 	);
 	// 6. Strip backtick wrapping around math: `$$...$$` → $$...$$ and `$...$` → $...$
 	content = content.replace(/`(\${1,2})((?:(?!\1).)+)\1`/g, "$1$2$1");
-	// 7. Same-line $$...$$ → $...$ (inline math) so it works inside table cells.
-	//    True display math has $$ on its own line, so this only affects inline usage.
-	content = content.replace(/\$\$([^\n]+?)\$\$/g, (_, inner) => `$${inner}$`);
+	// 7. Normalise single-dollar $...$ to double-dollar $$...$$ so they render
+	//    reliably in Streamdown (single-$ has strict no-space rules that often fail).
+	//    We match $…$ where the content starts with a backslash (LaTeX command)
+	//    to avoid converting currency like $50.
+	content = content.replace(
+		/(?<!\$)\$(?!\$)(\\[a-zA-Z][\s\S]*?)(?<!\$)\$(?!\$)/g,
+		(_, inner) => `$$${inner.trim()}$$`,
+	);
 	return content;
 }