From ebdce2f9569e6c3a513dafeb678fe8c985d1c835 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jos=C3=A9=20Almeida?=
 <57680069+zeval@users.noreply.github.com>
Date: Sat, 2 May 2026 18:53:59 +0100
Subject: [PATCH] fix: prevent inline code from rendering diagrams (#773)

* fix: prevent inline code from rendering diagrams

* fix: address markdown renderer review feedback

* fix: remove redundant markdown block detection
---
 .../shared/markdown-components.test.tsx       | 55 +++++++++++++++++++
 .../components/shared/markdown-components.tsx | 22 ++++++--
 2 files changed, 71 insertions(+), 6 deletions(-)
 create mode 100644 apps/web/components/shared/markdown-components.test.tsx

diff --git a/apps/web/components/shared/markdown-components.test.tsx b/apps/web/components/shared/markdown-components.test.tsx
new file mode 100644
index 0000000000..f94d747a06
--- /dev/null
+++ b/apps/web/components/shared/markdown-components.test.tsx
@@ -0,0 +1,55 @@
+import type { ReactNode } from "react";
+import ReactMarkdown from "react-markdown";
+import { renderToStaticMarkup } from "react-dom/server";
+import { describe, expect, it, vi } from "vitest";
+import { markdownComponents, remarkPlugins } from "./markdown-components";
+
+vi.mock("@/components/shared/mermaid-block", () => ({
+  MermaidBlock: ({ code }: { code: string }) => <div data-kind="mermaid">{code}</div>,
+}));
+
+vi.mock("@/components/task/chat/messages/code-block", () => ({
+  CodeBlock: ({ children, className }: { children: ReactNode; className?: string }) => (
+    <pre data-kind="block" className={className}>
+      <code>{children}</code>
+    </pre>
+  ),
+}));
+
+vi.mock("@/components/task/chat/messages/inline-code", () => ({
+  InlineCode: ({ children }: { children: ReactNode }) => <code data-kind="inline">{children}</code>,
+}));
+
+function renderMarkdown(source: string): string {
+  return renderToStaticMarkup(
+    <ReactMarkdown remarkPlugins={remarkPlugins} components={markdownComponents}>
+      {source}
+    </ReactMarkdown>,
+  );
+}
+
+describe("markdownComponents", () => {
+  it("keeps mermaid keywords in inline code as inline code", () => {
+    const html = renderMarkdown("Metadata comes from `kanban`, `kanbanMulti`, repositories.");
+
+    expect(html).toContain('data-kind="inline"');
+    expect(html).toContain("kanban");
+    expect(html).not.toContain('data-kind="mermaid"');
+  });
+
+  it("renders fenced mermaid code as a mermaid block", () => {
+    const html = renderMarkdown("```mermaid\ngraph LR\nA-->B\n```");
+
+    expect(html).toContain('data-kind="mermaid"');
+    expect(html).toContain("graph LR");
+  });
+
+  it("renders non-mermaid fenced code as a code block", () => {
+    const html = renderMarkdown("```ts\nconst source = 'kanban';\n```");
+
+    expect(html).toContain('data-kind="block"');
+    expect(html).toContain("language-ts");
+    expect(html).toContain("const source");
+    expect(html).not.toContain('data-kind="mermaid"');
+  });
+});
diff --git a/apps/web/components/shared/markdown-components.tsx b/apps/web/components/shared/markdown-components.tsx
index e6dd392511..d31a3e1304 100644
--- a/apps/web/components/shared/markdown-components.tsx
+++ b/apps/web/components/shared/markdown-components.tsx
@@ -39,6 +39,15 @@ export function getTextContent(children: ReactNode): string {
   return "";
 }
 
+type MarkdownCodeProps = {
+  className?: string;
+  children?: ReactNode;
+};
+
+function isBlockCode(rawContent: string, hasLanguage: boolean): boolean {
+  return hasLanguage || rawContent.includes("\n");
+}
+
 /**
  * Shared markdown component overrides for ReactMarkdown.
  * Element styles (headings, lists, inline code, etc.) are handled by
@@ -46,15 +55,16 @@ export function getTextContent(children: ReactNode): string {
  * (code routing, link target, table overflow wrapper) remain here.
  */
 export const markdownComponents = {
-  code: ({ className, children }: { className?: string; children?: ReactNode }) => {
-    const content = getTextContent(children).replace(/\n$/, "");
+  code: ({ className, children }: MarkdownCodeProps) => {
+    const rawContent = getTextContent(children);
+    const content = rawContent.replace(/\n$/, "");
     const lang = className?.replace("language-", "") ?? null;
-    if (isMermaidContent(lang, content)) {
+    const hasLanguage = className?.startsWith("language-") ?? false;
+    const isBlock = isBlockCode(rawContent, hasLanguage);
+    if (isBlock && isMermaidContent(lang, content)) {
       return <MermaidBlock code={content} />;
     }
-    const hasLanguage = className?.startsWith("language-");
-    const hasNewlines = content.includes("\n");
-    if (hasLanguage || hasNewlines) {
+    if (isBlock) {
       return <CodeBlock className={className}>{content}</CodeBlock>;
     }
     return <InlineCode>{content}</InlineCode>;