qa: hourly in-process heartbeat + run pruning

- runner: QA_HEARTBEAT_MIN (default 60) in-process timer runs a scheduled QA
  pass; one pulse ~90s after boot. Triage (LLM) skipped on clean scheduled runs
  to save tokens; only manual runs or runs with errors get a written summary.
- qa-finish.php prunes to the 50 most recent runs.
- systemd unit exposes QA_HEARTBEAT_MIN for tuning.

agents/console/server.mjs

@@ -796,7 +796,12 @@ async function runQaFlow(trigger) {
     runId = JSON.parse(start.out || "{}").run_id || 0;
     if (!runId) throw new Error("could not open a QA run");
     const { findings, counts } = await runQa();
-    const summary = await qaTriage(findings, counts);
+    // Triage (an LLM call) only when it's worth it: a manual run, or a
+    // scheduled heartbeat that actually found errors. Clean heartbeats get a
+    // cheap templated summary — no tokens spent when the site is fine.
+    const summary = (trigger === "manual" || counts.error > 0)
+      ? await qaTriage(findings, counts)
+      : `${counts.error} error(s) and ${counts.warning} warning(s) across ${counts.pages} pages.`;
     const tmp = `/tmp/qa-${runId}.json`;
     writeFileSync(tmp, JSON.stringify(findings));
     await phpCli(["api/cli/qa-finish.php", `--run=${runId}`, "--status=done", `--summary=${summary}`, `--counts=${JSON.stringify(counts)}`, `--findings-file=${tmp}`]);
@@ -993,3 +998,15 @@ if (!existsSync(PREVIEW_DIR)) mkdirSync(PREVIEW_DIR, { recursive: true });
 server.listen(PORT, "127.0.0.1", () => {
   console.log(`[console] runner on 127.0.0.1:${PORT}, repo ${REPO}`);
 });
+
+// ---- QA heartbeat ------------------------------------------------------------
+// The runner is long-lived, so the QA heartbeat is just an in-process timer —
+// no cron, no extra units. Runs a scheduled QA pass every QA_HEARTBEAT_MIN
+// minutes (0 disables), plus one pulse shortly after boot. runQaFlow self-guards
+// against overlap and is read-only against the live site.
+const QA_HEARTBEAT_MIN = Number(process.env.QA_HEARTBEAT_MIN || 60);
+if (QA_HEARTBEAT_MIN > 0) {
+  setTimeout(() => runQaFlow("scheduled"), 90_000); // first pulse ~90s after boot
+  setInterval(() => runQaFlow("scheduled"), QA_HEARTBEAT_MIN * 60_000);
+  console.log(`[qa] heartbeat every ${QA_HEARTBEAT_MIN} min`);
+}

api/cli/qa-finish.php

@@ -61,4 +61,11 @@ foreach ($findings as $f) {
 $upd = $pdo->prepare('UPDATE cja_qa_runs SET status = ?, summary = ?, counts = ?, finished_at = NOW() WHERE run_id = ?');
 $upd->execute([$status, $summary, $counts, $runId]);
 
+// Prune to the 50 most recent runs (the heartbeat runs often).
+$cut = (int) ($pdo->query('SELECT run_id FROM cja_qa_runs ORDER BY run_id DESC LIMIT 1 OFFSET 50')->fetchColumn() ?: 0);
+if ($cut > 0) {
+    $pdo->prepare('DELETE FROM cja_qa_findings WHERE run_id < ?')->execute([$cut]);
+    $pdo->prepare('DELETE FROM cja_qa_runs WHERE run_id < ?')->execute([$cut]);
+}
+
 echo json_encode(['ok' => true, 'run_id' => $runId, 'findings' => $n]);