Fix rich markdown editor HTML tag crashes

ui/src/components/MarkdownEditor.test.tsx

@@ -63,7 +63,7 @@ vi.mock("@mdxeditor/editor", async () => {
     }), []);
 
     React.useEffect(() => {
-      if (!suppressHtmlProcessing && markdown.includes("<img ")) {
+      if (!suppressHtmlProcessing && (markdown.includes("<img ") || markdown.includes("<gpt>"))) {
         setContent("");
         onError?.({
           error: "Error parsing markdown: HTML-like formatting requires suppressHtmlProcessing",
@@ -262,7 +262,7 @@ describe("MarkdownEditor", () => {
     await flush();
     expect(mdxEditorMockState.markdownValues.at(-1)).toContain("![image](https://example.com/test.png)");
     expect(mdxEditorMockState.markdownValues.at(-1)).not.toContain("<img");
-    expect(mdxEditorMockState.suppressHtmlProcessingValues).toContain(false);
+    expect(mdxEditorMockState.suppressHtmlProcessingValues).toContain(true);
     expect(container.textContent).toContain("Before");
     expect(container.textContent).toContain("After");
 
@@ -271,6 +271,30 @@ describe("MarkdownEditor", () => {
     });
   });
 
+  it("keeps LLM wrapper tags in the rich editor instead of falling back to raw source", async () => {
+    const root = createRoot(container);
+
+    await act(async () => {
+      root.render(
+        <MarkdownEditor
+          value={"<gpt>\n## My take\n\nBenchmark notes\n</gpt>"}
+          onChange={() => {}}
+          placeholder="Markdown body"
+        />,
+      );
+    });
+
+    await flush();
+    expect(mdxEditorMockState.suppressHtmlProcessingValues).toContain(true);
+    expect(container.querySelector("textarea")).toBeNull();
+    expect(container.textContent).toContain("Benchmark notes");
+    expect(container.textContent).not.toContain("Rich editor unavailable for this markdown");
+
+    await act(async () => {
+      root.unmount();
+    });
+  });
+
   it("falls back to a raw textarea when the rich parser rejects the markdown", async () => {
     mdxEditorMockState.emitMountParseError = true;
     const handleChange = vi.fn();

ui/src/components/MarkdownEditor.tsx

@@ -1084,6 +1084,7 @@ export const MarkdownEditor = forwardRef<MarkdownEditorRef, MarkdownEditorProps>
       <MDXEditor
         ref={setEditorRef}
         markdown={editorValue}
+        suppressHtmlProcessing
         placeholder={placeholder}
         readOnly={readOnly}
         onChange={(next) => {