diff --git a/NEXT_STEPS.md b/NEXT_STEPS.md
index 9de068c..7c2aa42 100644
--- a/NEXT_STEPS.md
+++ b/NEXT_STEPS.md
@@ -20,6 +20,7 @@ Estado al cierre:
   - `arts/sess/engine-session.ts` delega snapshot, generation, dispatch, persistencia y commits en `session-state.ts`.
   - `arts/sess/engine-session.ts` delega la resolucion de revoke local/global/degradado en `session-revoke.ts`.
   - `arts/conn/connection.ts` delega la programacion de reconnect y exhaustion en `connection-reconnect-runtime.ts`.
+  - `arts/timr/engine-timers.ts` delega fan-out de listeners y diagnostico de listeners en `timer-events.ts`.
 - Integracion total ampliada: `Auth.signOut()` valida anonimizacion, invalidacion de `Permissions` y evento `Cache.invalidate`.
 - Tanda focalizada verde: `npx vitest run src/arts/conn src/libs/cach src/arts/cach src/svrs/cach src/arts/auth src/svrs/auth src/libs/auth src/arts/aapp/test/ecosystem.integration.test.ts` -> 19 archivos, 82 tests.
 - `/test/ecosystem` revisado en navegador: carga sin errores de consola, `ar` cambia a `rtl`, Formats se actualiza por locale, Perm cambia con rol `viewer`, Cach re-scopea por locale y Conn loopback publica/recibe.
diff --git a/src/arts/timr/engine-timers.ts b/src/arts/timr/engine-timers.ts
index cd05f4b..700fbae 100644
--- a/src/arts/timr/engine-timers.ts
+++ b/src/arts/timr/engine-timers.ts
@@ -51,6 +51,7 @@ import {
 	timerEntrySnapshot,
 	type InternalTimerEntry
 } from './timer-entry.ts';
+import { createTimerEventBus } from './timer-events.ts';
 import { createTimerHandle } from './timer-handle.ts';
 import {
 	assertTimerDelay,
@@ -66,7 +67,6 @@ import type {
 	TimerHandle,
 	TimerIntervalOptions,
 	TimerKind,
-	TimerListener,
 	TimerOptions,
 	TimerTask,
 	TimerTaskContext
@@ -75,9 +75,9 @@ import type {
 export function createEngineTimers(options: EngineTimersOptions = {}): EngineTimers {
 	const clock: TimerClock = options.clock ?? createSystemTimerClock();
 	const diagnostics = createTimerDiagnostics(options.logger);
+	const events = createTimerEventBus(diagnostics);
 
 	const entries = new Map<string, InternalTimerEntry>();
-	const listeners = new Set<TimerListener>();
 
 	let disposed = false;
 	let nextId = 1;
@@ -89,16 +89,7 @@ export function createEngineTimers(options: EngineTimersOptions = {}): EngineTim
 	// ── Listener fan-out ────────────────────────────────────────────────────
 
 	function emit(event: TimerEvent): void {
-		for (const listener of listeners) {
-			try {
-				listener(event);
-			} catch (err) {
-				emitTimerDiagnostic(diagnostics, TIMER_DIAGNOSTIC_EVENTS.LISTENER_THREW, {
-					error: err,
-					event: event.type
-				});
-			}
-		}
+		events.emit(event);
 	}
 
 	// ── Entry lifecycle ─────────────────────────────────────────────────────
@@ -421,10 +412,7 @@ export function createEngineTimers(options: EngineTimersOptions = {}): EngineTim
 
 		onChange(listener) {
 			if (disposed) return () => {};
-			listeners.add(listener);
-			return () => {
-				listeners.delete(listener);
-			};
+			return events.on(listener);
 		},
 
 		dispose() {
@@ -434,7 +422,7 @@ export function createEngineTimers(options: EngineTimersOptions = {}): EngineTim
 			const all = Array.from(entries.values());
 			for (const entry of all) cancelEntry(entry);
 			emit({ type: TIMER_EVENT_DISPOSED });
-			listeners.clear();
+			events.clear();
 		}
 	};
 
diff --git a/src/arts/timr/timer-events.ts b/src/arts/timr/timer-events.ts
new file mode 100644
index 0000000..3214e00
--- /dev/null
+++ b/src/arts/timr/timer-events.ts
@@ -0,0 +1,37 @@
+import { TIMER_DIAGNOSTIC_EVENTS } from './consts.ts';
+import { emitTimerDiagnostic, type TimerDiagnostics } from './diagnostics.ts';
+import type { TimerEvent, TimerListener } from './types.ts';
+
+export interface TimerEventBus {
+	emit(event: TimerEvent): void;
+	on(listener: TimerListener): () => void;
+	clear(): void;
+}
+
+export function createTimerEventBus(diagnostics: TimerDiagnostics): TimerEventBus {
+	const listeners = new Set<TimerListener>();
+
+	return {
+		emit(event) {
+			for (const listener of listeners) {
+				try {
+					listener(event);
+				} catch (err) {
+					emitTimerDiagnostic(diagnostics, TIMER_DIAGNOSTIC_EVENTS.LISTENER_THREW, {
+						error: err,
+						event: event.type
+					});
+				}
+			}
+		},
+		on(listener) {
+			listeners.add(listener);
+			return () => {
+				listeners.delete(listener);
+			};
+		},
+		clear() {
+			listeners.clear();
+		}
+	};
+}