diff --git a/runtime/coach/trigger-tuner.js b/runtime/coach/trigger-tuner.js
index d6d69de..a99d370 100644
--- a/runtime/coach/trigger-tuner.js
+++ b/runtime/coach/trigger-tuner.js
@@ -39,7 +39,15 @@ export function attach({ intervalMs = TUNE_INTERVAL_MS } = {}) {
 		return;
 	}
 	_timer = setInterval(() => {
-		runOnce().catch((e) => warn("tuner", `tick err: ${e?.message ?? e}`));
+		// runOnce is synchronous (pure SQL, no await) — must NOT call
+		// .catch on its plain-object return. A try/catch here is the
+		// correct guard. (This exact bug crashed the live bot after
+		// ~1h uptime when the first tuner tick fired.)
+		try {
+			runOnce();
+		} catch (e) {
+			warn("tuner", `tick err: ${e?.message ?? e}`);
+		}
 	}, intervalMs);
 	_timer.unref?.();
 	info("tuner", `attached; tune every ${Math.round(intervalMs / 60000)} min`);
diff --git a/runtime/coach/trigger-tuner.test.js b/runtime/coach/trigger-tuner.test.js
index 7021727..7cdd124 100644
--- a/runtime/coach/trigger-tuner.test.js
+++ b/runtime/coach/trigger-tuner.test.js
@@ -6,10 +6,31 @@ import { join } from "node:path";
 
 import { initKnowledge, isAvailable, listImprovements } from "../knowledge/index.js";
 import { closeStore, __resetForTests } from "../knowledge/store.js";
-import { runOnce, __testing } from "./trigger-tuner.js";
+import { runOnce, attach, detach, __testing } from "./trigger-tuner.js";
 
 const { MIN_SAMPLE } = __testing;
 
+test("attach: timer tick does not crash (runOnce is sync, regression for .catch bug)", async () => {
+	// Reproduces the crash that killed the live bot after ~1h: the
+	// setInterval body called runOnce().catch(...) but runOnce returns
+	// a plain object, not a Promise. attach must guard with try/catch.
+	detach();
+	let threw = false;
+	const origSetInterval = globalThis.setInterval;
+	let captured = null;
+	// capture the interval callback without actually waiting
+	globalThis.setInterval = (fn) => { captured = fn; return { unref() {} }; };
+	try {
+		attach({ intervalMs: 999999 });
+		// invoke the captured tick synchronously — must not throw
+		try { captured?.(); } catch { threw = true; }
+	} finally {
+		globalThis.setInterval = origSetInterval;
+		detach();
+	}
+	assert.equal(threw, false, "tuner timer tick must not throw");
+});
+
 async function bootstrap() {
 	const tmp = mkdtempSync(join(tmpdir(), "pepa-tuner-test-"));
 	__resetForTests();