feat(audio-sequences): beat phase sync and aligned playback

Add bar-phase tracking, audio reset/anchor APIs, BPM holdover, beat-phase
sequence switching, sync-phase endpoint, and sample sequence data.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/controllers/sequence.py

@@ -30,6 +30,7 @@ def get_current_profile_id(session=None):
 @with_session
 async def list_sequences(request, session):
     """List sequences for the current profile."""
+    sequences.load()
     current_profile_id = get_current_profile_id(session)
     if not current_profile_id:
         return json.dumps({}), 200, {"Content-Type": "application/json"}
@@ -97,6 +98,7 @@ async def import_sequence(request, session):
 @with_session
 async def get_sequence(request, session, id):
     """Get a specific sequence by ID (current profile only)."""
+    sequences.load()
     current_profile_id = get_current_profile_id(session)
     seq = sequences.read(id)
     if (
@@ -203,15 +205,46 @@ async def delete_sequence(request, session, id):
     return json.dumps({"error": "Sequence not found"}), 404
 
 
+@controller.post("/sync-phase")
+@with_session
+async def sync_sequence_beat_phase(request, session):
+    """Align beat counters while a sequence is playing (body: {\"mode\": \"step\"|\"pass\"})."""
+    _ = session
+    try:
+        data = request.json or {}
+    except Exception:
+        data = {}
+    if not isinstance(data, dict):
+        data = {}
+    mode = data.get("mode") or data.get("align") or "step"
+    try:
+        from util.sequence_playback import sync_beat_phase
+
+        if not await sync_beat_phase(str(mode)):
+            return (
+                json.dumps({"error": "No sequence is playing"}),
+                409,
+                {"Content-Type": "application/json"},
+            )
+        from util.audio_detector import anchor_shared_bar_phase
+
+        anchor_shared_bar_phase()
+        return json.dumps({"ok": True, "mode": str(mode).strip().lower()}), 200, {
+            "Content-Type": "application/json"
+        }
+    except Exception as e:
+        return json.dumps({"error": str(e)}), 500, {"Content-Type": "application/json"}
+
+
 @controller.post("/stop")
 @with_session
 async def stop_sequence_playback(request, session):
     """Stop server-driven zone sequence playback."""
     _ = request
     try:
-        from util.sequence_playback import stop
+        from util.sequence_playback import stop_playback
 
-        stop()
+        await stop_playback(clear_devices=True)
         return json.dumps({"ok": True}), 200, {"Content-Type": "application/json"}
     except Exception as e:
         return json.dumps({"error": str(e)}), 500, {"Content-Type": "application/json"}
@@ -251,8 +284,12 @@ async def play_sequence(request, session, id):
     try:
         from util.sequence_playback import start
 
-        await start(zone_id, str(id), str(current_profile_id), data if isinstance(data, dict) else None)
-        return json.dumps({"ok": True}), 200, {"Content-Type": "application/json"}
+        play_opts = data if isinstance(data, dict) else None
+        await start(zone_id, str(id), str(current_profile_id), play_opts)
+        from util.sequence_playback import pending_play_status
+
+        body = {"ok": True, **pending_play_status()}
+        return json.dumps(body), 200, {"Content-Type": "application/json"}
     except ValueError as e:
         return json.dumps({"error": str(e)}), 400, {"Content-Type": "application/json"}
     except RuntimeError as e: