fix(best-practices): respect existing heading in #bp-summary

src/core/best-practices.js

@@ -57,8 +57,13 @@ export function run() {
   });
   if (bps.length) {
     if (bpSummary) {
-      bpSummary.appendChild(html`<h1>Best Practices Summary</h1>`);
-      if (summaryItems) bpSummary.appendChild(summaryItems);
+      const existingHeading = bpSummary.querySelector(
+        ":scope > :is(h1, h2, h3, h4, h5, h6)"
+      );
+      if (!existingHeading) {
+        bpSummary.prepend(html`<h1>Best Practices Summary</h1>`);
+      }
+      if (summaryItems) bpSummary.append(summaryItems);
     }
   } else if (bpSummary) {
     const msg = `Using best practices summary (#bp-summary) but no best practices found.`;

tests/spec/core/best-practices-spec.js

@@ -81,4 +81,29 @@ describe("Core — Best Practices", () => {
     );
     expect(bps.querySelectorAll("ul li")).toHaveSize(3);
   });
+
+  it("does not duplicate heading when bp-summary already has one", async () => {
+    const body = `
+      <section id="bps">
+        <h2>Section</h2>
+        <span class='practicelab'>BP1</span>
+        <section id='bp-summary'>
+          <h2>Custom Heading</h2>
+        </section>
+      </section>
+    `;
+    const ops = {
+      config: makeBasicConfig(),
+      body,
+    };
+    const doc = await makeRSDoc(ops);
+    const bpSummary = doc.getElementById("bp-summary");
+    const headings = bpSummary.querySelectorAll("h1, h2, h3, h4, h5, h6");
+    expect(headings).toHaveSize(1);
+    expect(headings[0].textContent).toContain("Custom Heading");
+
+    const listItems = bpSummary.querySelectorAll("ul li");
+    expect(listItems).toHaveSize(1);
+    expect(listItems[0].textContent.trim()).toBe("Best Practice 1: BP1");
+  });
 });