Add preset tracks with OGG stems and metadata overrides for key/BPM detection

- Add 6 preset tracks as OGG Vorbis (~10x smaller than WAV, no audible quality loss)
- Add metadata.json override system for presets with incorrect MIDI detection
- Fix Sea-to-Sky and Ocean-to-Horizon BPM (90 instead of 95)
- Fix Silver-lining key (D major instead of G major)
- Fix Static-Summer key (A major instead of D major)
- Backend resolves .ogg before .wav for forward/backward compatibility

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitattributes

@@ -34,3 +34,4 @@ saved_model/**/* filter=lfs diff=lfs merge=lfs -text
 *.zst filter=lfs diff=lfs merge=lfs -text
 *tfevents* filter=lfs diff=lfs merge=lfs -text
 backend/presets/**/*.wav filter=lfs diff=lfs merge=lfs -text
+backend/presets/**/*.ogg filter=lfs diff=lfs merge=lfs -text

backend/models/session.py

@@ -36,6 +36,8 @@ class Session:
     original_sr: int = 44100
     # Cache for encoded WAV bytes to avoid re-encoding on each request
     wav_cache: dict[str, bytes] = field(default_factory=dict)
+    # Optional metadata overrides loaded from preset's metadata.json
+    preset_metadata: Optional[dict] = None
 
 
 # In-memory session store

backend/presets/{sample-track/bass.wav → 274-SUNSPILL/bass.ogg}

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:34d0bf1999390c1846ec635d7d13f719f12235dd0c3b43aff37c978defd20166
-size 70893820
+oid sha256:19e3c525887f1cc0e9fc54e7604b07e273d3d7be5a6b642c7dc155ac7679d7ef
+size 1775218

backend/presets/{sample-track/click_record.wav → 274-SUNSPILL/click_record.ogg}

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:436b475a472014349fe08f7acee5916bf17d1ff475471b6f04b45e1cf3f67233
-size 70893820
+oid sha256:7c3cda91ce4b648c6a624dcde24994275d8a06ed9575aca33f8ee159229e7ad5
+size 677440

backend/presets/{sample-track/drums.wav → 274-SUNSPILL/drums.ogg}

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:536d1b91df21e93ca9f1f1352da5b70f64e6b0b8ac884e7ef794122f63183cfd
-size 70893820
+oid sha256:e52f1689c33fc77996692739a8b468f2570523cf83d7ae2f65d9c52b1afa79ef
+size 5849946

backend/presets/{sample-track/guitar.wav → 274-SUNSPILL/guitar.ogg}

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:8ed112603fd68bed8a61c290b9ca36fcecee998b085eb283a21e127df0b2bc9e
-size 70893820
+oid sha256:32c4165659d43522bffb3ad4d3f8984fb4139bbac78091d24708ee1520752996
+size 4202989

backend/presets/274-SUNSPILL/synth.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:37fef05c433225778d69ca05e0792504f7bdda87d13b4595787efc20748725bd
+size 4969407

backend/presets/281-New-Drive/click_record.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:b57f2056adad41ebdf5c857906087196fac0a15c513e54a12c5e2a5898be63aa
+size 955426

backend/presets/281-New-Drive/drums.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:1b225eacde295cb8d5171fa5caac8c009c9dd661f86d9b9dd90e57be2f838698
+size 9873395

backend/presets/281-New-Drive/guitar.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:8edfbb3d8d8fb6eca4d332f39e0c0b7f946fd27618da01c730e6136564b80c9e
+size 6052516

backend/presets/281-New-Drive/synth.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:0d48b8df19153c8dee5f3d8b03e31613506a5f3aaf93d3e51895d3718ee42e3a
+size 3570314

backend/presets/282-Static-Summer/click_record.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:599d74905a741a7acd33931ff89373f469fe98edd27b543e9563472692de3214
+size 1275261

backend/presets/282-Static-Summer/drums.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:6175a8ce69bc827eb939da4f9c67fe7d4a1def1118eb3965bda7617b087a3dfa
+size 14258389

backend/presets/282-Static-Summer/guitar.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:010119a51c2078573cfa91e9521cc20b5d0eac0944e710ec993672e01ea1a341
+size 9248029

backend/presets/282-Static-Summer/metadata.json

@@ -0,0 +1 @@
+{ "key": "A", "mode": "major" }

backend/presets/282-Static-Summer/synth.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:7a85e1128abb36af56ef122d5c46935f93defa8883666d05d44059e64e7e0ac0
+size 10177662

backend/presets/291-Blue-Jazz/click_record.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:c509be5861393346b9171e4fae7d6da1258dbba01890c91d43b7c026f83ad974
+size 1248321

backend/presets/291-Blue-Jazz/drums.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:3d07798a8b0c2087f2cd672f5a111063ded392b1c3151121684228010b80b1e1
+size 17954847

backend/presets/291-Blue-Jazz/guitar.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:b68969f1be0e5b77c76f71cc51a58c4f3607a84ea30ad6bb09a5fedfae23235b
+size 7622816

backend/presets/291-Blue-Jazz/synth.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:e94da4bf9cce3ef54df934286d9c5d043152bdaf655f34f13e653ef37f533404
+size 5147257

backend/presets/292-Silver-lining/click_record.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:64bcb9637c8f29f2192035fd03f56be5a05cb4e0f8d6fe7d8baddf8a9ad88745
+size 1224237

backend/presets/292-Silver-lining/drums.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:1141913045b3a85cfba368d32a748c6bbd83514f48384dd41d3dadb2f849da06
+size 13762812

backend/presets/292-Silver-lining/guitar.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:1327a2b61936f78d514a3c528ca604379c69399f6e1d28de8f51f5aa9afcc8ba
+size 6776410

backend/presets/292-Silver-lining/metadata.json

@@ -0,0 +1 @@
+{ "key": "D", "mode": "major" }

backend/presets/292-Silver-lining/synth.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:28cd6533535ad035391a864687d5f6fe1bbede08e2e6a090b07655be9a6e3cc4
+size 5794283

backend/presets/294-Sea-to-Sky/click_record.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:ba642c37eca52f14055a320b3b105bc52b73e711e6c69e036eb24dff05437bbe
+size 1294507

backend/presets/294-Sea-to-Sky/drums.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:e66ca65d5e4b034442e8a106b01c32d352a2f723964ad222b3f9cbbee6287b70
+size 11734610

backend/presets/294-Sea-to-Sky/guitar.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:887f057845958f0fccbfb1cb867b16e564ac6dc8b8f59aa407f1b949c6f70185
+size 7145674

backend/presets/294-Sea-to-Sky/metadata.json

@@ -0,0 +1 @@
+{ "bpm": 90 }

backend/presets/294-Sea-to-Sky/synth.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:924694244bea0ee8e022bf86bedd8516cb4b51b23f579b5c2e18eb111b2cf52c
+size 5323721

backend/presets/295-Ocean-to-Horizon/click_record.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:f5d69c2527d02d8f25694149c0c55f7e1b2636fbc09bcd8ae0bd7eadc2c99fd7
+size 1294507

backend/presets/295-Ocean-to-Horizon/drums.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:4d97ad6d139174592d9dacbd8c260cc291a5f1a8e0fbe5866b430ff24bf7b167
+size 11734851

backend/presets/295-Ocean-to-Horizon/guitar.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:a3c6458920495eec37134e11a514c8983670818de9069d67b02f9a2a7f6e9a5e
+size 7235754

backend/presets/295-Ocean-to-Horizon/metadata.json

@@ -0,0 +1 @@
+{ "bpm": 90 }

backend/presets/295-Ocean-to-Horizon/synth.ogg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:822c8d86bbb900451978218c0ca657771cb2caa46d1054924bda6ad70ad0c612
+size 4499162

backend/presets/sample-track/synth.wav

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:ba8a34d85b65a69e09ba0a319136bba8c9d92a6e0fa10e9dc3770d6e26d25a49
-size 70893820

backend/routers/detection.py

@@ -29,11 +29,22 @@ async def detect_bpm_and_key(session_id: str):
     if session.full_mix is None:
         raise HTTPException(status_code=400, detail="No audio data in session")
 
+    # Preset metadata overrides — highest priority, skips all detection
+    meta = session.preset_metadata or {}
+    bpm_override = meta.get("bpm")
+    key_override = meta.get("key")
+    mode_override = meta.get("mode")
+
     # BPM Detection - prefer MIDI (instant)
     bpm_source = "audio"
     bpm_result = None
 
-    if session.midi_data is not None:
+    if bpm_override is not None:
+        bpm_result = {"bpm": float(bpm_override), "confidence": 1.0}
+        bpm_source = "preset"
+        print(f"BPM from preset metadata: {bpm_result['bpm']}")
+
+    elif session.midi_data is not None:
         # Use MIDI directly - it's exact data
         bpm_result = extract_bpm_from_midi(session.midi_data)
         bpm_source = "midi"
@@ -63,7 +74,12 @@ async def detect_bpm_and_key(session_id: str):
     key_source = "audio"
     key_result = None
 
-    if session.midi_data is not None:
+    if key_override is not None and mode_override is not None:
+        key_result = {"key": key_override, "mode": mode_override, "confidence": 1.0}
+        key_source = "preset"
+        print(f"Key from preset metadata: {key_result['key']} {key_result['mode']}")
+
+    elif session.midi_data is not None:
         # Use MIDI directly
         key_result = extract_key_from_midi(session.midi_data)
         if key_result["confidence"] > 0:  # Accept any MIDI key result

backend/routers/presets.py

@@ -3,6 +3,7 @@
 from pathlib import Path
 
 import io
+import json
 import numpy as np
 import soundfile as sf
 import mido
@@ -16,6 +17,7 @@ router = APIRouter()
 
 PRESETS_DIR = Path(__file__).parent.parent / "presets"
 STEM_NAMES = ['guitar', 'drums', 'bass', 'synth', 'click_record']
+AUDIO_EXTENSIONS = ['.ogg', '.wav']  # prefer OGG, fall back to WAV
 
 
 @router.get("/presets")
@@ -30,9 +32,15 @@ async def list_presets():
 @router.get("/preset-stem/{preset_name}/{stem_name}")
 async def get_preset_stem_pcm(preset_name: str, stem_name: str):
     """Serve a single preset stem as raw int16 PCM — stateless, no session created."""
-    wav_path = PRESETS_DIR / preset_name / f"{stem_name}.wav"
-    if not wav_path.exists():
+    audio_path = None
+    for ext in AUDIO_EXTENSIONS:
+        candidate = PRESETS_DIR / preset_name / f"{stem_name}{ext}"
+        if candidate.exists():
+            audio_path = candidate
+            break
+    if audio_path is None:
         raise HTTPException(status_code=404, detail=f"Stem '{stem_name}' not found in preset '{preset_name}'")
+    wav_path = audio_path
 
     audio, sr = sf.read(str(wav_path))
     audio = audio.astype(np.float32)
@@ -66,9 +74,15 @@ async def load_preset(preset_name: str):
     sample_rates = []
 
     for stem_name in STEM_NAMES:
-        wav_path = preset_dir / f"{stem_name}.wav"
-        if not wav_path.exists():
+        audio_path = None
+        for ext in AUDIO_EXTENSIONS:
+            candidate = preset_dir / f"{stem_name}{ext}"
+            if candidate.exists():
+                audio_path = candidate
+                break
+        if audio_path is None:
             continue
+        wav_path = audio_path
         audio, sr = sf.read(str(wav_path))
         audio = audio.astype(np.float32)
         if audio.ndim == 2:
@@ -95,11 +109,19 @@ async def load_preset(preset_name: str):
         except Exception as e:
             print(f"Warning: could not load MIDI from preset '{preset_name}': {e}")
 
+    # Load metadata overrides if present
+    preset_metadata = None
+    metadata_path = preset_dir / "metadata.json"
+    if metadata_path.exists():
+        with open(metadata_path) as f:
+            preset_metadata = json.load(f)
+
     # Build session
     session = create_session()
     session.stems = stems
     session.original_sr = sample_rates[0]
     session.midi_data = midi_data
+    session.preset_metadata = preset_metadata
 
     # Generate mix
     max_length = max(len(s.audio) for s in stems.values())