test: pin the brace-aware template-hole strip with its own fixture

The hole strip shipped with no counterfactual: reverting it alone left every
corpus walk and all four new fixtures green, because the only observable
difference is two corpus lines nothing asserted. Add the fixture, which reds
on the old regex.

Also correct the plainText doc comment. It named … as motivating the
second whitespace collapse, but that decodes to '...', which is not
whitespace. Only   motivates it.

Author: vivek7405

website/lib/docs-llms.server.ts

@@ -140,7 +140,8 @@ function oneLine(s: string): string {
  * decode. Exported for the same reason `bodyToMarkdown` is, so a unit test
  * can drive it on a fixture instead of planting scaffolding in a real docs
  * page. The whitespace collapse is re-run after decoding because ` `
- * and `…` only become whitespace-relevant once decoded.
+ * decodes to a literal space, so a run of them is only collapsible once the
+ * decode has happened.
  */
 export function plainText(s: string): string {
   return decodeEntities(oneLine(s)).replace(/\s+/g, ' ').trim();

website/test/ssr/docs-llms.test.ts

@@ -164,6 +164,16 @@ test('an escaped tag in prose survives to the corpus', () => {
   assert.equal(md, 'a value with <code> here');
 });
 
+test('a nested template hole leaves no debris behind', () => {
+  // The hole strip used to be `\$\{[^}]*\}`, which stops at the FIRST `}`, so
+  // the nested hole /docs/architecture authors left `"}` in the prose. It was
+  // invisible while the runaway strip above deleted the whole fragment, and
+  // reader-visible once the decode ordering was fixed, which is why the two
+  // ship together.
+  const md = bodyToMarkdown('html`<p>a <code>&lt;form action=${"${createPost}"}&gt;</code> posts</p>`');
+  assert.equal(md, 'a <form action=> posts');
+});
+
 test('plainText strips tags before it decodes entities', () => {
   assert.equal(plainText('a value with &lt;code&gt; here'), 'a value with <code> here');
   assert.match(plainText('intercepts same-origin &lt;a&gt; clicks'), /same-origin <a> clicks/);