fix(prd): stop body lines being read as a PRD's title and status (#42)

listPrds scanned the first sixteen lines of each PRD and kept the last
`title:`/`status:` match it found, without stopping at the closing `---`.
A PRD whose body starts a line with one of those keys — a YAML sample in a
fenced code block, say — therefore had its real front matter overwritten, so
`prd list` and the README index showed the sample's values instead.

Parse the delimited front-matter block instead. Files with no front matter
now fall back to the slug and `?` rather than lifting values out of prose.
Existing PRDs render byte-identically.

Co-authored-by: clawedassistant26 <307253840+clawedassistant26@users.noreply.github.com>

Author: clawedassistant26

src/prd.mjs

@@ -199,6 +199,19 @@ function unquoteYaml(value) {
   return raw;
 }
 
+// The front matter is the block between the leading `---` and its closing
+// `---`; everything after that is prose. Reading a fixed window of leading
+// lines instead let a body line that merely starts with `title:`/`status:` —
+// a YAML sample in a fenced code block, say — win, because the scan kept the
+// last match it saw anywhere in the window. It also cut off longer front
+// matter. Return the block itself, or nothing when the file has none.
+function frontMatter(text) {
+  const lines = text.split(/\r?\n/);
+  if (lines[0]?.trim() !== "---") return [];
+  const end = lines.findIndex((l, i) => i > 0 && l.trim() === "---");
+  return end === -1 ? [] : lines.slice(1, end);
+}
+
 /** List numbered PRDs (NNNN-slug.md, excluding the 0000 template). */
 export function listPrds(root = process.cwd()) {
   const base = prdDir(root);
@@ -211,7 +224,7 @@ export function listPrds(root = process.cwd()) {
     const file = path.join(base, name);
     let title = m[2], status = "?";
     try {
-      const head = fs.readFileSync(file, "utf8").split(/\r?\n/).slice(0, 16);
+      const head = frontMatter(fs.readFileSync(file, "utf8"));
       for (const l of head) {
         const t = l.match(/^title:\s*(.+)$/); if (t) title = unquoteYaml(t[1]);
         const s = l.match(/^status:\s*(.+)$/); if (s) status = unquoteYaml(s[1]);

test/prd.test.mjs

@@ -108,3 +108,62 @@ test("createPrd hides the whole idea even when it contains a comment terminator"
     fs.rmSync(root, { recursive: true, force: true });
   }
 });
+
+test("listPrds ignores body lines that look like front matter", () => {
+  // A PRD documenting an API often shows a YAML sample in a fenced block. Those
+  // lines start at column 0 like real keys do, so a scan that runs past the
+  // closing `---` reads them as the PRD's own title and status.
+  const root = fs.mkdtempSync(path.join(os.tmpdir(), "moshcode-prd-"));
+  try {
+    const dir = path.join(root, "prd");
+    fs.mkdirSync(dir, { recursive: true });
+    fs.writeFileSync(path.join(dir, "0001-job-api.md"), [
+      "---",
+      'title: "Job API v2"',
+      "status: Accepted",
+      "---",
+      "",
+      "## Requirements",
+      "",
+      "- R1 [P0] Return the job record:",
+      "",
+      "```yaml",
+      "title: nightly-import",
+      "status: queued",
+      "```",
+      "",
+    ].join("\n"));
+
+    const [prd] = listPrds(root);
+    assert.equal(prd.title, "Job API v2");
+    assert.equal(prd.status, "Accepted");
+  } finally {
+    fs.rmSync(root, { recursive: true, force: true });
+  }
+});
+
+test("listPrds does not take a title or status from a PRD with no front matter", () => {
+  // A doc dropped into prd/ without front matter has no declared status. Prose
+  // is not front matter, so fall back to the slug and the unknown marker rather
+  // than lifting whatever a line happens to start with.
+  const root = fs.mkdtempSync(path.join(os.tmpdir(), "moshcode-prd-"));
+  try {
+    const dir = path.join(root, "prd");
+    fs.mkdirSync(dir, { recursive: true });
+    fs.writeFileSync(path.join(dir, "0002-import-notes.md"), [
+      "# Import notes",
+      "",
+      "Fields the importer needs from each upstream row:",
+      "",
+      "title: taken from the H1",
+      "status: derived, never authored by hand",
+      "",
+    ].join("\n"));
+
+    const [prd] = listPrds(root);
+    assert.equal(prd.title, "import-notes");
+    assert.equal(prd.status, "?");
+  } finally {
+    fs.rmSync(root, { recursive: true, force: true });
+  }
+});