fix(client-runtime): media tables with indented cells split line by line

Indented HTML in a cell would render as a markdown code block once the cell is
split on its own, so such tables keep main's line-by-line split.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: juliusmarminge

packages/client-runtime/src/pullRequestMarkdown.test.ts

@@ -239,6 +239,11 @@ describe("media tables", () => {
     ],
     ["an unclosed table", "<table>\n<tr><td>", ""],
     ["a spanning cell", '<table>\n<tr><td colspan="2">', "</td></tr>\n</table>"],
+    [
+      "an indented cell",
+      "<table>\n  <tr>\n    <th>\n      Before\n    </th>\n  </tr>\n  <tr><td>",
+      "</td></tr>\n</table>",
+    ],
   ])("splits a media table with %s line by line, as before", (_name, open, close) => {
     const body = `${open}\n\n${video}\n\n${close}`;
     expect(splitPullRequestBody(body)).toEqual([

packages/client-runtime/src/pullRequestMarkdown.ts

@@ -100,12 +100,13 @@ function tableRows(html: string, htmlOffset: number): TableRows | null {
     const tag = match[2]!.toLowerCase();
     if (cell !== null) {
       if (!closing || tag !== cell.tag) return null;
+      const content = html.slice(cell.contentStart, match.index);
+      // Indented HTML would render as a code block once the cell is markdown on its own.
+      if (content.split("\n").some((line) => INDENTED_CODE_PATTERN.test(line) && line.trim()))
+        return null;
       row!.push({
         header: tag === "th",
-        segments: splitBodyAt(
-          html.slice(cell.contentStart, match.index),
-          htmlOffset + cell.contentStart,
-        ),
+        segments: splitBodyAt(content, htmlOffset + cell.contentStart),
       });
       cell = null;
     } else {