diff --git a/playground/js/event-bus.js b/playground/js/event-bus.js
new file mode 100644
index 0000000..abd7821
--- /dev/null
+++ b/playground/js/event-bus.js
@@ -0,0 +1,117 @@
+// Namespaced Event Bus
+// Lightweight pub/sub with seq.*/ml.*/ui.* namespaces and wildcard support.
+
+// ── Event name constants ────────────────────────────────────────────
+
+export const SEQ = Object.freeze({
+  STEP:         'seq.step',
+  NOTE_ON:      'seq.noteOn',
+  NOTE_OFF:     'seq.noteOff',
+  PARAM_CHANGE: 'seq.paramChange',
+  LOOP_START:   'seq.loopStart',
+});
+
+export const ML = Object.freeze({
+  TRAINED:      'ml.trained',
+  FROZEN:       'ml.frozen',
+  UNFROZEN:     'ml.unfrozen',
+  DELTA_UPDATE: 'ml.deltaUpdate',
+});
+
+export const UI = Object.freeze({
+  PARAM_SELECT:  'ui.paramSelect',
+  CHAIN_EDIT:    'ui.chainEdit',
+  PRESET_LOAD:   'ui.presetLoad',
+  FREEZE_TOGGLE: 'ui.freezeToggle',
+});
+
+// ── Bus implementation ──────────────────────────────────────────────
+
+export class EventBus {
+  /** @param {AudioContext} [audioCtx] - optional, used for seq.* timestamps */
+  constructor(audioCtx) {
+    this._listeners = new Map();   // event -> Set<callback>
+    this._wildcards = new Map();   // namespace prefix (e.g. "seq") -> Set<callback>
+    this._audioCtx = audioCtx ?? null;
+  }
+
+  /** Provide or replace the AudioContext used for seq.* timestamps. */
+  setAudioContext(ctx) {
+    this._audioCtx = ctx;
+  }
+
+  /**
+   * Subscribe to an event or a wildcard namespace.
+   *   on('seq.step', cb)   — exact match
+   *   on('seq.*', cb)      — all events in the seq namespace
+   */
+  on(event, callback) {
+    if (event.endsWith('.*')) {
+      const ns = event.slice(0, -2); // "seq.*" -> "seq"
+      if (!this._wildcards.has(ns)) this._wildcards.set(ns, new Set());
+      this._wildcards.get(ns).add(callback);
+    } else {
+      if (!this._listeners.has(event)) this._listeners.set(event, new Set());
+      this._listeners.get(event).add(callback);
+    }
+  }
+
+  /** Unsubscribe. Mirrors the on() signature. */
+  off(event, callback) {
+    if (event.endsWith('.*')) {
+      const ns = event.slice(0, -2);
+      const set = this._wildcards.get(ns);
+      if (set) {
+        set.delete(callback);
+        if (set.size === 0) this._wildcards.delete(ns);
+      }
+    } else {
+      const set = this._listeners.get(event);
+      if (set) {
+        set.delete(callback);
+        if (set.size === 0) this._listeners.delete(event);
+      }
+    }
+  }
+
+  /**
+   * Emit an event.
+   * A `timestamp` field is added automatically:
+   *   - seq.* events use AudioContext.currentTime (seconds)
+   *   - all others use performance.now() (milliseconds)
+   */
+  emit(event, data = {}) {
+    const ns = event.split('.')[0];
+    const stamped = Object.assign({ timestamp: this._stamp(ns) }, data);
+
+    // Exact listeners
+    const exact = this._listeners.get(event);
+    if (exact) {
+      for (const cb of exact) cb(stamped, event);
+    }
+
+    // Wildcard listeners for this namespace
+    const wild = this._wildcards.get(ns);
+    if (wild) {
+      for (const cb of wild) cb(stamped, event);
+    }
+  }
+
+  // ── private ──
+
+  _stamp(ns) {
+    if (ns === 'seq' && this._audioCtx) return this._audioCtx.currentTime;
+    return performance.now();
+  }
+}
+
+// ── Singleton convenience ───────────────────────────────────────────
+
+let _default = null;
+
+/** Return (and lazily create) the shared default bus. */
+export function getDefaultBus(audioCtx) {
+  if (!_default) _default = new EventBus(audioCtx);
+  else if (audioCtx) _default.setAudioContext(audioCtx);
+  return _default;
+}
diff --git a/playground/js/shapeseq/event-bus.js b/playground/js/shapeseq/event-bus.js
index eaf22ab..4a8d585 100644
--- a/playground/js/shapeseq/event-bus.js
+++ b/playground/js/shapeseq/event-bus.js
@@ -1,117 +1,2 @@
-// ShapeSeq Namespaced Event Bus
-// Lightweight pub/sub with seq.*/ml.*/ui.* namespaces and wildcard support.
-
-// ── Event name constants ────────────────────────────────────────────
-
-export const SEQ = Object.freeze({
-  STEP:         'seq.step',
-  NOTE_ON:      'seq.noteOn',
-  NOTE_OFF:     'seq.noteOff',
-  PARAM_CHANGE: 'seq.paramChange',
-  LOOP_START:   'seq.loopStart',
-});
-
-export const ML = Object.freeze({
-  TRAINED:      'ml.trained',
-  FROZEN:       'ml.frozen',
-  UNFROZEN:     'ml.unfrozen',
-  DELTA_UPDATE: 'ml.deltaUpdate',
-});
-
-export const UI = Object.freeze({
-  PARAM_SELECT:  'ui.paramSelect',
-  CHAIN_EDIT:    'ui.chainEdit',
-  PRESET_LOAD:   'ui.presetLoad',
-  FREEZE_TOGGLE: 'ui.freezeToggle',
-});
-
-// ── Bus implementation ──────────────────────────────────────────────
-
-export class EventBus {
-  /** @param {AudioContext} [audioCtx] - optional, used for seq.* timestamps */
-  constructor(audioCtx) {
-    this._listeners = new Map();   // event -> Set<callback>
-    this._wildcards = new Map();   // namespace prefix (e.g. "seq") -> Set<callback>
-    this._audioCtx = audioCtx ?? null;
-  }
-
-  /** Provide or replace the AudioContext used for seq.* timestamps. */
-  setAudioContext(ctx) {
-    this._audioCtx = ctx;
-  }
-
-  /**
-   * Subscribe to an event or a wildcard namespace.
-   *   on('seq.step', cb)   — exact match
-   *   on('seq.*', cb)      — all events in the seq namespace
-   */
-  on(event, callback) {
-    if (event.endsWith('.*')) {
-      const ns = event.slice(0, -2); // "seq.*" -> "seq"
-      if (!this._wildcards.has(ns)) this._wildcards.set(ns, new Set());
-      this._wildcards.get(ns).add(callback);
-    } else {
-      if (!this._listeners.has(event)) this._listeners.set(event, new Set());
-      this._listeners.get(event).add(callback);
-    }
-  }
-
-  /** Unsubscribe. Mirrors the on() signature. */
-  off(event, callback) {
-    if (event.endsWith('.*')) {
-      const ns = event.slice(0, -2);
-      const set = this._wildcards.get(ns);
-      if (set) {
-        set.delete(callback);
-        if (set.size === 0) this._wildcards.delete(ns);
-      }
-    } else {
-      const set = this._listeners.get(event);
-      if (set) {
-        set.delete(callback);
-        if (set.size === 0) this._listeners.delete(event);
-      }
-    }
-  }
-
-  /**
-   * Emit an event.
-   * A `timestamp` field is added automatically:
-   *   - seq.* events use AudioContext.currentTime (seconds)
-   *   - all others use performance.now() (milliseconds)
-   */
-  emit(event, data = {}) {
-    const ns = event.split('.')[0];
-    const stamped = Object.assign({ timestamp: this._stamp(ns) }, data);
-
-    // Exact listeners
-    const exact = this._listeners.get(event);
-    if (exact) {
-      for (const cb of exact) cb(stamped, event);
-    }
-
-    // Wildcard listeners for this namespace
-    const wild = this._wildcards.get(ns);
-    if (wild) {
-      for (const cb of wild) cb(stamped, event);
-    }
-  }
-
-  // ── private ──
-
-  _stamp(ns) {
-    if (ns === 'seq' && this._audioCtx) return this._audioCtx.currentTime;
-    return performance.now();
-  }
-}
-
-// ── Singleton convenience ───────────────────────────────────────────
-
-let _default = null;
-
-/** Return (and lazily create) the shared default bus. */
-export function getDefaultBus(audioCtx) {
-  if (!_default) _default = new EventBus(audioCtx);
-  else if (audioCtx) _default.setAudioContext(audioCtx);
-  return _default;
-}
+// playground/js/shapeseq/event-bus.js — re-exports from shared module
+export { EventBus, SEQ, ML, UI, getDefaultBus } from '../event-bus.js';