Initial commit

backend/services/__init__.py

@@ -0,0 +1 @@
+# Services layer — generation orchestration and background task management.

backend/services/channels.py

@@ -0,0 +1,263 @@
+"""
+Audio channel management module.
+"""
+
+from typing import List, Optional
+from datetime import datetime
+import uuid
+from sqlalchemy.orm import Session
+
+from ..models import (
+    AudioChannelCreate,
+    AudioChannelUpdate,
+    AudioChannelResponse,
+    ChannelVoiceAssignment,
+    ProfileChannelAssignment,
+)
+from ..database import (
+    AudioChannel as DBAudioChannel,
+    ChannelDeviceMapping as DBChannelDeviceMapping,
+    ProfileChannelMapping as DBProfileChannelMapping,
+    VoiceProfile as DBVoiceProfile,
+)
+
+
+async def list_channels(db: Session) -> List[AudioChannelResponse]:
+    """List all audio channels."""
+    channels = db.query(DBAudioChannel).all()
+    result = []
+    
+    for channel in channels:
+        # Get device IDs for this channel
+        device_mappings = db.query(DBChannelDeviceMapping).filter_by(
+            channel_id=channel.id
+        ).all()
+        device_ids = [m.device_id for m in device_mappings]
+        
+        result.append(AudioChannelResponse(
+            id=channel.id,
+            name=channel.name,
+            is_default=channel.is_default,
+            device_ids=device_ids,
+            created_at=channel.created_at,
+        ))
+    
+    return result
+
+
+async def get_channel(channel_id: str, db: Session) -> Optional[AudioChannelResponse]:
+    """Get a channel by ID."""
+    channel = db.query(DBAudioChannel).filter_by(id=channel_id).first()
+    if not channel:
+        return None
+    
+    # Get device IDs
+    device_mappings = db.query(DBChannelDeviceMapping).filter_by(
+        channel_id=channel.id
+    ).all()
+    device_ids = [m.device_id for m in device_mappings]
+    
+    return AudioChannelResponse(
+        id=channel.id,
+        name=channel.name,
+        is_default=channel.is_default,
+        device_ids=device_ids,
+        created_at=channel.created_at,
+    )
+
+
+async def create_channel(
+    data: AudioChannelCreate,
+    db: Session,
+) -> AudioChannelResponse:
+    """Create a new audio channel."""
+    # Check if name already exists
+    existing = db.query(DBAudioChannel).filter_by(name=data.name).first()
+    if existing:
+        raise ValueError(f"Channel with name '{data.name}' already exists")
+    
+    # Create channel
+    channel = DBAudioChannel(
+        id=str(uuid.uuid4()),
+        name=data.name,
+        is_default=False,
+        created_at=datetime.utcnow(),
+    )
+    db.add(channel)
+    db.flush()
+    
+    # Add device mappings
+    for device_id in data.device_ids:
+        mapping = DBChannelDeviceMapping(
+            id=str(uuid.uuid4()),
+            channel_id=channel.id,
+            device_id=device_id,
+        )
+        db.add(mapping)
+    
+    db.commit()
+    db.refresh(channel)
+    
+    return AudioChannelResponse(
+        id=channel.id,
+        name=channel.name,
+        is_default=channel.is_default,
+        device_ids=data.device_ids,
+        created_at=channel.created_at,
+    )
+
+
+async def update_channel(
+    channel_id: str,
+    data: AudioChannelUpdate,
+    db: Session,
+) -> Optional[AudioChannelResponse]:
+    """Update an audio channel."""
+    channel = db.query(DBAudioChannel).filter_by(id=channel_id).first()
+    if not channel:
+        return None
+    
+    if channel.is_default:
+        raise ValueError("Cannot modify the default channel")
+    
+    # Update name if provided
+    if data.name is not None:
+        # Check if name already exists (excluding current channel)
+        existing = db.query(DBAudioChannel).filter(
+            DBAudioChannel.name == data.name,
+            DBAudioChannel.id != channel_id
+        ).first()
+        if existing:
+            raise ValueError(f"Channel with name '{data.name}' already exists")
+        channel.name = data.name
+    
+    # Update device mappings if provided
+    if data.device_ids is not None:
+        # Delete existing mappings
+        db.query(DBChannelDeviceMapping).filter_by(channel_id=channel_id).delete()
+        
+        # Add new mappings
+        for device_id in data.device_ids:
+            mapping = DBChannelDeviceMapping(
+                id=str(uuid.uuid4()),
+                channel_id=channel.id,
+                device_id=device_id,
+            )
+            db.add(mapping)
+    
+    db.commit()
+    db.refresh(channel)
+    
+    # Get updated device IDs
+    device_mappings = db.query(DBChannelDeviceMapping).filter_by(
+        channel_id=channel.id
+    ).all()
+    device_ids = [m.device_id for m in device_mappings]
+    
+    return AudioChannelResponse(
+        id=channel.id,
+        name=channel.name,
+        is_default=channel.is_default,
+        device_ids=device_ids,
+        created_at=channel.created_at,
+    )
+
+
+async def delete_channel(channel_id: str, db: Session) -> bool:
+    """Delete an audio channel."""
+    channel = db.query(DBAudioChannel).filter_by(id=channel_id).first()
+    if not channel:
+        return False
+    
+    if channel.is_default:
+        raise ValueError("Cannot delete the default channel")
+    
+    # Delete device mappings
+    db.query(DBChannelDeviceMapping).filter_by(channel_id=channel_id).delete()
+    
+    # Delete profile-channel mappings
+    db.query(DBProfileChannelMapping).filter_by(channel_id=channel_id).delete()
+    
+    # Delete channel
+    db.delete(channel)
+    db.commit()
+    
+    return True
+
+
+async def get_channel_voices(channel_id: str, db: Session) -> List[str]:
+    """Get list of profile IDs assigned to a channel."""
+    mappings = db.query(DBProfileChannelMapping).filter_by(
+        channel_id=channel_id
+    ).all()
+    return [m.profile_id for m in mappings]
+
+
+async def set_channel_voices(
+    channel_id: str,
+    data: ChannelVoiceAssignment,
+    db: Session,
+) -> None:
+    """Set which voices are assigned to a channel."""
+    # Verify channel exists
+    channel = db.query(DBAudioChannel).filter_by(id=channel_id).first()
+    if not channel:
+        raise ValueError(f"Channel {channel_id} not found")
+    
+    # Verify all profiles exist
+    for profile_id in data.profile_ids:
+        profile = db.query(DBVoiceProfile).filter_by(id=profile_id).first()
+        if not profile:
+            raise ValueError(f"Profile {profile_id} not found")
+    
+    # Delete existing mappings for this channel
+    db.query(DBProfileChannelMapping).filter_by(channel_id=channel_id).delete()
+    
+    # Add new mappings
+    for profile_id in data.profile_ids:
+        mapping = DBProfileChannelMapping(
+            profile_id=profile_id,
+            channel_id=channel_id,
+        )
+        db.add(mapping)
+    
+    db.commit()
+
+
+async def get_profile_channels(profile_id: str, db: Session) -> List[str]:
+    """Get list of channel IDs assigned to a profile."""
+    mappings = db.query(DBProfileChannelMapping).filter_by(
+        profile_id=profile_id
+    ).all()
+    return [m.channel_id for m in mappings]
+
+
+async def set_profile_channels(
+    profile_id: str,
+    data: ProfileChannelAssignment,
+    db: Session,
+) -> None:
+    """Set which channels a profile is assigned to."""
+    # Verify profile exists
+    profile = db.query(DBVoiceProfile).filter_by(id=profile_id).first()
+    if not profile:
+        raise ValueError(f"Profile {profile_id} not found")
+    
+    # Verify all channels exist
+    for channel_id in data.channel_ids:
+        channel = db.query(DBAudioChannel).filter_by(id=channel_id).first()
+        if not channel:
+            raise ValueError(f"Channel {channel_id} not found")
+    
+    # Delete existing mappings for this profile
+    db.query(DBProfileChannelMapping).filter_by(profile_id=profile_id).delete()
+    
+    # Add new mappings
+    for channel_id in data.channel_ids:
+        mapping = DBProfileChannelMapping(
+            profile_id=profile_id,
+            channel_id=channel_id,
+        )
+        db.add(mapping)
+    
+    db.commit()

backend/services/cuda.py

@@ -0,0 +1,422 @@
+"""
+CUDA backend download, assembly, and verification.
+
+Downloads two archives from GitHub Releases:
+  1. Server core (voicebox-server-cuda.tar.gz) — the exe + non-NVIDIA deps,
+     versioned with the app.
+  2. CUDA libs (cuda-libs-{version}.tar.gz) — NVIDIA runtime libraries,
+     versioned independently (only redownloaded on CUDA toolkit bump).
+
+Both archives are extracted into {data_dir}/backends/cuda/ which forms the
+complete PyInstaller --onedir directory structure that torch expects.
+"""
+
+import asyncio
+import hashlib
+import json
+import logging
+import os
+import sys
+import tarfile
+from pathlib import Path
+from typing import Optional
+
+from ..config import get_data_dir
+from ..utils.progress import get_progress_manager
+from .. import __version__
+
+logger = logging.getLogger(__name__)
+
+GITHUB_RELEASES_URL = "https://github.com/jamiepine/voicebox/releases/download"
+
+PROGRESS_KEY = "cuda-backend"
+
+# The current expected CUDA libs version.  Bump this when we change the
+# CUDA toolkit version or torch's CUDA dependency changes (e.g. cu126 -> cu128).
+CUDA_LIBS_VERSION = "cu128-v1"
+
+# Prevents concurrent download_cuda_binary() calls from racing on the same
+# temp file.  The auto-update background task and the manual HTTP endpoint
+# can both invoke download_cuda_binary(); without this lock the progress-
+# manager status check is a TOCTOU race.
+_download_lock = asyncio.Lock()
+
+
+def get_backends_dir() -> Path:
+    """Directory where downloaded backend binaries are stored."""
+    d = get_data_dir() / "backends"
+    d.mkdir(parents=True, exist_ok=True)
+    return d
+
+
+def get_cuda_dir() -> Path:
+    """Directory where the CUDA backend (onedir) is extracted."""
+    d = get_backends_dir() / "cuda"
+    d.mkdir(parents=True, exist_ok=True)
+    return d
+
+
+def get_cuda_exe_name() -> str:
+    """Platform-specific CUDA executable filename."""
+    if sys.platform == "win32":
+        return "voicebox-server-cuda.exe"
+    return "voicebox-server-cuda"
+
+
+def get_cuda_binary_path() -> Optional[Path]:
+    """Return path to the CUDA executable if it exists inside the onedir."""
+    p = get_cuda_dir() / get_cuda_exe_name()
+    if p.exists():
+        return p
+    return None
+
+
+def get_cuda_libs_manifest_path() -> Path:
+    """Path to the cuda-libs.json manifest inside the CUDA dir."""
+    return get_cuda_dir() / "cuda-libs.json"
+
+
+def get_installed_cuda_libs_version() -> Optional[str]:
+    """Read the installed CUDA libs version from cuda-libs.json, or None."""
+    manifest_path = get_cuda_libs_manifest_path()
+    if not manifest_path.exists():
+        return None
+    try:
+        data = json.loads(manifest_path.read_text())
+        return data.get("version")
+    except Exception as e:
+        logger.warning(f"Could not read cuda-libs.json: {e}")
+        return None
+
+
+def is_cuda_active() -> bool:
+    """Check if the current process is the CUDA binary.
+
+    The CUDA binary sets this env var on startup (see server.py).
+    """
+    return os.environ.get("VOICEBOX_BACKEND_VARIANT") == "cuda"
+
+
+def get_cuda_status() -> dict:
+    """Get current CUDA backend status for the API."""
+    progress_manager = get_progress_manager()
+    cuda_path = get_cuda_binary_path()
+    progress = progress_manager.get_progress(PROGRESS_KEY)
+    cuda_libs_version = get_installed_cuda_libs_version()
+
+    return {
+        "available": cuda_path is not None,
+        "active": is_cuda_active(),
+        "binary_path": str(cuda_path) if cuda_path else None,
+        "cuda_libs_version": cuda_libs_version,
+        "downloading": progress is not None and progress.get("status") == "downloading",
+        "download_progress": progress,
+    }
+
+
+def _needs_server_download(version: Optional[str] = None) -> bool:
+    """Check if the server core archive needs to be (re)downloaded."""
+    cuda_path = get_cuda_binary_path()
+    if not cuda_path:
+        return True
+    # Check if the binary version matches the expected app version
+    installed = get_cuda_binary_version()
+    expected = version or __version__
+    if expected.startswith("v"):
+        expected = expected[1:]
+    return installed != expected
+
+
+def _needs_cuda_libs_download() -> bool:
+    """Check if the CUDA libs archive needs to be (re)downloaded."""
+    installed = get_installed_cuda_libs_version()
+    if installed is None:
+        return True
+    return installed != CUDA_LIBS_VERSION
+
+
+async def _download_and_extract_archive(
+    client,
+    url: str,
+    sha256_url: Optional[str],
+    dest_dir: Path,
+    label: str,
+    progress_offset: int,
+    total_size: int,
+):
+    """Download a .tar.gz archive and extract it into dest_dir.
+
+    Args:
+        client: httpx.AsyncClient
+        url: URL of the .tar.gz archive
+        sha256_url: URL of the .sha256 checksum file (optional)
+        dest_dir: Directory to extract into
+        label: Human-readable label for progress updates
+        progress_offset: Byte offset for progress reporting (when downloading
+            multiple archives sequentially)
+        total_size: Total bytes across all downloads (for progress bar)
+    """
+    progress = get_progress_manager()
+    temp_path = dest_dir / f".download-{label.replace(' ', '-')}.tmp"
+
+    # Clean up leftover partial download
+    if temp_path.exists():
+        temp_path.unlink()
+
+    # Fetch expected checksum (fail-fast: never extract an unverified archive)
+    expected_sha = None
+    if sha256_url:
+        try:
+            sha_resp = await client.get(sha256_url)
+            sha_resp.raise_for_status()
+            expected_sha = sha_resp.text.strip().split()[0]
+            logger.info(f"{label}: expected SHA-256: {expected_sha[:16]}...")
+        except Exception as e:
+            raise RuntimeError(f"{label}: failed to fetch checksum from {sha256_url}") from e
+
+    # Stream download, verify, and extract — always clean up temp file
+    downloaded = 0
+    try:
+        async with client.stream("GET", url) as response:
+            response.raise_for_status()
+            with open(temp_path, "wb") as f:
+                async for chunk in response.aiter_bytes(chunk_size=1024 * 1024):
+                    f.write(chunk)
+                    downloaded += len(chunk)
+                    progress.update_progress(
+                        PROGRESS_KEY,
+                        current=progress_offset + downloaded,
+                        total=total_size,
+                        filename=f"Downloading {label}",
+                        status="downloading",
+                    )
+
+        # Verify integrity
+        if expected_sha:
+            progress.update_progress(
+                PROGRESS_KEY,
+                current=progress_offset + downloaded,
+                total=total_size,
+                filename=f"Verifying {label}...",
+                status="downloading",
+            )
+            sha256 = hashlib.sha256()
+            with open(temp_path, "rb") as f:
+                while True:
+                    data = f.read(1024 * 1024)
+                    if not data:
+                        break
+                    sha256.update(data)
+            actual = sha256.hexdigest()
+            if actual != expected_sha:
+                raise ValueError(
+                    f"{label} integrity check failed: expected {expected_sha[:16]}..., got {actual[:16]}..."
+                )
+            logger.info(f"{label}: integrity verified")
+
+        # Extract (use data filter for path traversal protection on Python 3.12+)
+        progress.update_progress(
+            PROGRESS_KEY,
+            current=progress_offset + downloaded,
+            total=total_size,
+            filename=f"Extracting {label}...",
+            status="downloading",
+        )
+        with tarfile.open(temp_path, "r:gz") as tar:
+            if sys.version_info >= (3, 12):
+                tar.extractall(path=dest_dir, filter="data")
+            else:
+                tar.extractall(path=dest_dir)
+
+        logger.info(f"{label}: extracted to {dest_dir}")
+    finally:
+        if temp_path.exists():
+            temp_path.unlink()
+    return downloaded
+
+
+async def download_cuda_binary(version: Optional[str] = None):
+    """Download the CUDA backend (server core + CUDA libs if needed).
+
+    Downloads both archives from GitHub Releases, extracts them into
+    {data_dir}/backends/cuda/, and writes the cuda-libs.json manifest.
+
+    Only downloads what's needed:
+    - Server core: always redownloaded (versioned with app)
+    - CUDA libs: only if missing or version mismatch
+
+    Args:
+        version: Version tag (e.g. "v0.3.0"). Defaults to current app version.
+    """
+    if _download_lock.locked():
+        logger.info("CUDA download already in progress, skipping duplicate request")
+        return
+    async with _download_lock:
+        await _download_cuda_binary_locked(version)
+
+
+async def _download_cuda_binary_locked(version: Optional[str] = None):
+    """Inner implementation of download_cuda_binary, called under _download_lock."""
+    import httpx
+
+    if version is None:
+        version = f"v{__version__}"
+
+    progress = get_progress_manager()
+    cuda_dir = get_cuda_dir()
+
+    need_server = _needs_server_download(version)
+    need_libs = _needs_cuda_libs_download()
+
+    if not need_server and not need_libs:
+        logger.info("CUDA backend is up to date, nothing to download")
+        return
+
+    logger.info(
+        f"Starting CUDA backend download for {version} "
+        f"(server={'yes' if need_server else 'cached'}, "
+        f"libs={'yes' if need_libs else 'cached'})"
+    )
+    progress.update_progress(
+        PROGRESS_KEY,
+        current=0,
+        total=0,
+        filename="Preparing download...",
+        status="downloading",
+    )
+
+    base_url = f"{GITHUB_RELEASES_URL}/{version}"
+    server_archive = "voicebox-server-cuda.tar.gz"
+    libs_archive = f"cuda-libs-{CUDA_LIBS_VERSION}.tar.gz"
+
+    try:
+        async with httpx.AsyncClient(follow_redirects=True, timeout=30.0) as client:
+            # Estimate total download size
+            total_size = 0
+            if need_server:
+                try:
+                    head = await client.head(f"{base_url}/{server_archive}")
+                    total_size += int(head.headers.get("content-length", 0))
+                except Exception:
+                    pass
+            if need_libs:
+                try:
+                    head = await client.head(f"{base_url}/{libs_archive}")
+                    total_size += int(head.headers.get("content-length", 0))
+                except Exception:
+                    pass
+
+            logger.info(f"Total download size: {total_size / 1024 / 1024:.1f} MB")
+
+            offset = 0
+
+            # Download server core
+            if need_server:
+                server_downloaded = await _download_and_extract_archive(
+                    client,
+                    url=f"{base_url}/{server_archive}",
+                    sha256_url=f"{base_url}/{server_archive}.sha256",
+                    dest_dir=cuda_dir,
+                    label="CUDA server",
+                    progress_offset=offset,
+                    total_size=total_size,
+                )
+                offset += server_downloaded
+
+                # Make executable on Unix
+                exe_path = cuda_dir / get_cuda_exe_name()
+                if sys.platform != "win32" and exe_path.exists():
+                    exe_path.chmod(0o755)
+
+            # Download CUDA libs
+            if need_libs:
+                await _download_and_extract_archive(
+                    client,
+                    url=f"{base_url}/{libs_archive}",
+                    sha256_url=f"{base_url}/{libs_archive}.sha256",
+                    dest_dir=cuda_dir,
+                    label="CUDA libraries",
+                    progress_offset=offset,
+                    total_size=total_size,
+                )
+
+                # Write local cuda-libs.json manifest
+                manifest = {"version": CUDA_LIBS_VERSION}
+                get_cuda_libs_manifest_path().write_text(json.dumps(manifest, indent=2) + "\n")
+
+        logger.info(f"CUDA backend ready at {cuda_dir}")
+        progress.mark_complete(PROGRESS_KEY)
+
+    except Exception as e:
+        logger.error(f"CUDA backend download failed: {e}")
+        progress.mark_error(PROGRESS_KEY, str(e))
+        raise
+
+
+def get_cuda_binary_version() -> Optional[str]:
+    """Get the version of the installed CUDA binary, or None if not installed."""
+    import subprocess
+
+    cuda_path = get_cuda_binary_path()
+    if not cuda_path:
+        return None
+    try:
+        result = subprocess.run(
+            [str(cuda_path), "--version"],
+            capture_output=True,
+            text=True,
+            timeout=30,
+            cwd=str(cuda_path.parent),  # Run from the onedir directory
+        )
+        # Output format: "voicebox-server 0.3.0"
+        for line in result.stdout.strip().splitlines():
+            if "voicebox-server" in line:
+                return line.split()[-1]
+    except Exception as e:
+        logger.warning(f"Could not get CUDA binary version: {e}")
+    return None
+
+
+async def check_and_update_cuda_binary():
+    """Check if the CUDA binary is outdated and auto-download if so.
+
+    Called on server startup. Checks both server version and CUDA libs
+    version. Downloads only what's needed.
+    """
+    cuda_path = get_cuda_binary_path()
+    if not cuda_path:
+        return  # No CUDA binary installed, nothing to update
+
+    need_server = _needs_server_download()
+    need_libs = _needs_cuda_libs_download()
+
+    if not need_server and not need_libs:
+        logger.info(f"CUDA binary is up to date (server=v{__version__}, libs={get_installed_cuda_libs_version()})")
+        return
+
+    reasons = []
+    if need_server:
+        cuda_version = get_cuda_binary_version()
+        reasons.append(f"server v{cuda_version} != v{__version__}")
+    if need_libs:
+        installed_libs = get_installed_cuda_libs_version()
+        reasons.append(f"libs {installed_libs} != {CUDA_LIBS_VERSION}")
+
+    logger.info(f"CUDA backend needs update ({', '.join(reasons)}). Auto-downloading...")
+
+    try:
+        await download_cuda_binary()
+    except Exception as e:
+        logger.error(f"Auto-update of CUDA binary failed: {e}")
+
+
+async def delete_cuda_binary() -> bool:
+    """Delete the downloaded CUDA backend directory. Returns True if deleted."""
+    import shutil
+
+    cuda_dir = get_cuda_dir()
+    if cuda_dir.exists() and any(cuda_dir.iterdir()):
+        shutil.rmtree(cuda_dir)
+        logger.info(f"Deleted CUDA backend directory: {cuda_dir}")
+        return True
+    return False

backend/services/effects.py

@@ -0,0 +1,120 @@
+"""
+Effect presets CRUD operations.
+"""
+
+from __future__ import annotations
+
+import json
+import uuid
+from typing import List, Optional
+
+from sqlalchemy.orm import Session
+from sqlalchemy.exc import IntegrityError
+
+from ..utils.effects import validate_effects_chain
+
+from ..database import EffectPreset as DBEffectPreset
+from ..models import EffectPresetResponse, EffectPresetCreate, EffectPresetUpdate, EffectConfig
+
+
+def _preset_response(p: DBEffectPreset) -> EffectPresetResponse:
+    """Convert a DB preset row to a Pydantic response."""
+    effects_chain = [EffectConfig(**e) for e in json.loads(p.effects_chain)]
+    return EffectPresetResponse(
+        id=p.id,
+        name=p.name,
+        description=p.description,
+        effects_chain=effects_chain,
+        is_builtin=p.is_builtin or False,
+        created_at=p.created_at,
+    )
+
+
+def list_presets(db: Session) -> List[EffectPresetResponse]:
+    """List all effect presets (built-in + user-created)."""
+    presets = db.query(DBEffectPreset).order_by(DBEffectPreset.sort_order, DBEffectPreset.name).all()
+    return [_preset_response(p) for p in presets]
+
+
+def get_preset(preset_id: str, db: Session) -> Optional[EffectPresetResponse]:
+    """Get a preset by ID."""
+    p = db.query(DBEffectPreset).filter_by(id=preset_id).first()
+    if not p:
+        return None
+    return _preset_response(p)
+
+
+def get_preset_by_name(name: str, db: Session) -> Optional[EffectPresetResponse]:
+    """Get a preset by name."""
+    p = db.query(DBEffectPreset).filter_by(name=name).first()
+    if not p:
+        return None
+    return _preset_response(p)
+
+
+def create_preset(data: EffectPresetCreate, db: Session) -> EffectPresetResponse:
+    """Create a new user effect preset."""
+
+    chain_dicts = [e.model_dump() for e in data.effects_chain]
+    error = validate_effects_chain(chain_dicts)
+    if error:
+        raise ValueError(error)
+
+    # Check for duplicate name before insert
+    existing = db.query(DBEffectPreset).filter_by(name=data.name).first()
+    if existing:
+        raise ValueError(f"A preset named '{data.name}' already exists")
+
+    preset = DBEffectPreset(
+        id=str(uuid.uuid4()),
+        name=data.name,
+        description=data.description,
+        effects_chain=json.dumps(chain_dicts),
+        is_builtin=False,
+    )
+    db.add(preset)
+    try:
+        db.commit()
+    except IntegrityError:
+        db.rollback()
+        raise ValueError(f"A preset named '{data.name}' already exists")
+    db.refresh(preset)
+    return _preset_response(preset)
+
+
+def update_preset(preset_id: str, data: EffectPresetUpdate, db: Session) -> Optional[EffectPresetResponse]:
+    """Update a user effect preset. Cannot modify built-in presets."""
+    preset = db.query(DBEffectPreset).filter_by(id=preset_id).first()
+    if not preset:
+        return None
+    if preset.is_builtin:
+        raise ValueError("Cannot modify built-in presets")
+
+    if data.name is not None:
+        preset.name = data.name
+    if data.description is not None:
+        preset.description = data.description
+    if data.effects_chain is not None:
+
+        chain_dicts = [e.model_dump() for e in data.effects_chain]
+        error = validate_effects_chain(chain_dicts)
+        if error:
+            raise ValueError(error)
+        preset.effects_chain = json.dumps(chain_dicts)
+
+    db.commit()
+    db.refresh(preset)
+    return _preset_response(preset)
+
+
+def delete_preset(preset_id: str, db: Session) -> bool:
+    """Delete a user effect preset. Cannot delete built-in presets."""
+    preset = db.query(DBEffectPreset).filter_by(id=preset_id).first()
+    if not preset:
+        return False
+    if preset.is_builtin:
+        raise ValueError("Cannot delete built-in presets")
+
+    db.delete(preset)
+    db.commit()
+    return True

backend/services/export_import.py

@@ -0,0 +1,461 @@
+"""
+Voice profile export/import module.
+
+Handles exporting profiles to ZIP archives and importing them back.
+Also handles exporting individual generations.
+"""
+
+import json
+import zipfile
+import io
+from pathlib import Path
+from typing import Optional
+from sqlalchemy.orm import Session
+
+from ..models import VoiceProfileResponse
+from ..database import VoiceProfile as DBVoiceProfile, ProfileSample as DBProfileSample, Generation as DBGeneration, GenerationVersion as DBGenerationVersion
+from .profiles import create_profile, add_profile_sample
+from ..models import VoiceProfileCreate
+from .. import config
+
+
+def _get_unique_profile_name(name: str, db: Session) -> str:
+    """
+    Get a unique profile name by appending a number if needed.
+    
+    Args:
+        name: Original profile name
+        db: Database session
+        
+    Returns:
+        Unique profile name
+    """
+    base_name = name
+    counter = 1
+    
+    while True:
+        existing = db.query(DBVoiceProfile).filter_by(name=name).first()
+        if not existing:
+            return name
+        
+        name = f"{base_name} ({counter})"
+        counter += 1
+
+
+def export_profile_to_zip(profile_id: str, db: Session) -> bytes:
+    """
+    Export a voice profile to a ZIP archive.
+    
+    Args:
+        profile_id: Profile ID to export
+        db: Database session
+        
+    Returns:
+        ZIP file contents as bytes
+        
+    Raises:
+        ValueError: If profile not found or has no samples
+    """
+    # Get profile
+    profile = db.query(DBVoiceProfile).filter_by(id=profile_id).first()
+    if not profile:
+        raise ValueError(f"Profile {profile_id} not found")
+    
+    # Get all samples
+    samples = db.query(DBProfileSample).filter_by(profile_id=profile_id).all()
+    if not samples:
+        raise ValueError(f"Profile {profile_id} has no samples")
+    
+    # Create ZIP in memory
+    zip_buffer = io.BytesIO()
+    
+    with zipfile.ZipFile(zip_buffer, 'w', zipfile.ZIP_DEFLATED) as zip_file:
+        # Check if profile has avatar
+        has_avatar = False
+        if profile.avatar_path:
+            avatar_path = config.resolve_storage_path(profile.avatar_path)
+            if avatar_path is not None and avatar_path.exists():
+                has_avatar = True
+                # Add avatar to ZIP root with original extension
+                avatar_ext = avatar_path.suffix
+                zip_file.write(avatar_path, f"avatar{avatar_ext}")
+
+        # Create manifest.json
+        manifest = {
+            "version": "1.0",
+            "profile": {
+                "name": profile.name,
+                "description": profile.description,
+                "language": profile.language,
+            },
+            "has_avatar": has_avatar,
+        }
+        zip_file.writestr("manifest.json", json.dumps(manifest, indent=2))
+
+        # Create samples.json mapping
+        samples_data = {}
+        profile_dir = config.get_profiles_dir() / profile_id
+
+        for sample in samples:
+            # Get filename from audio_path (should be {sample_id}.wav)
+            audio_path = config.resolve_storage_path(sample.audio_path)
+            if audio_path is None:
+                raise ValueError(f"Audio file not found: {sample.audio_path}")
+            filename = audio_path.name
+
+            # Read audio file
+            if not audio_path.exists():
+                raise ValueError(f"Audio file not found: {audio_path}")
+
+            # Add to samples directory in ZIP
+            zip_path = f"samples/{filename}"
+            zip_file.write(audio_path, zip_path)
+
+            # Map filename to reference text
+            samples_data[filename] = sample.reference_text
+
+        zip_file.writestr("samples.json", json.dumps(samples_data, indent=2))
+    
+    zip_buffer.seek(0)
+    return zip_buffer.read()
+
+
+async def import_profile_from_zip(file_bytes: bytes, db: Session) -> VoiceProfileResponse:
+    """
+    Import a voice profile from a ZIP archive.
+    
+    Args:
+        file_bytes: ZIP file contents
+        db: Database session
+        
+    Returns:
+        Created profile
+        
+    Raises:
+        ValueError: If ZIP is invalid or missing required files
+    """
+    zip_buffer = io.BytesIO(file_bytes)
+    
+    try:
+        with zipfile.ZipFile(zip_buffer, 'r') as zip_file:
+            # Validate ZIP structure
+            namelist = zip_file.namelist()
+            
+            if "manifest.json" not in namelist:
+                raise ValueError("ZIP archive missing manifest.json")
+            
+            if "samples.json" not in namelist:
+                raise ValueError("ZIP archive missing samples.json")
+            
+            # Read manifest
+            manifest_data = json.loads(zip_file.read("manifest.json"))
+            
+            if "version" not in manifest_data:
+                raise ValueError("Invalid manifest.json: missing version")
+            
+            if "profile" not in manifest_data:
+                raise ValueError("Invalid manifest.json: missing profile")
+            
+            profile_data = manifest_data["profile"]
+            
+            # Read samples mapping
+            samples_data = json.loads(zip_file.read("samples.json"))
+            
+            if not isinstance(samples_data, dict):
+                raise ValueError("Invalid samples.json: must be a dictionary")
+            
+            # Get unique profile name
+            original_name = profile_data.get("name", "Imported Profile")
+            unique_name = _get_unique_profile_name(original_name, db)
+            
+            # Create profile
+            profile_create = VoiceProfileCreate(
+                name=unique_name,
+                description=profile_data.get("description"),
+                language=profile_data.get("language", "en"),
+            )
+            
+            profile = await create_profile(profile_create, db)
+
+            # Extract and add samples
+            profile_dir = config.get_profiles_dir() / profile.id
+            profile_dir.mkdir(parents=True, exist_ok=True)
+
+            # Handle avatar if present
+            avatar_files = [f for f in namelist if f.startswith("avatar.")]
+            if avatar_files:
+                try:
+                    avatar_file = avatar_files[0]
+                    # Extract to temporary file
+                    import tempfile
+                    with tempfile.NamedTemporaryFile(suffix=Path(avatar_file).suffix, delete=False) as tmp:
+                        tmp.write(zip_file.read(avatar_file))
+                        tmp_path = tmp.name
+
+                    try:
+                        from .profiles import upload_avatar
+                        await upload_avatar(profile.id, tmp_path, db)
+                    finally:
+                        Path(tmp_path).unlink(missing_ok=True)
+                except Exception as e:
+                    # Avatar import is optional - continue even if it fails
+                    pass
+
+            for filename, reference_text in samples_data.items():
+                # Validate filename
+                if not filename.endswith('.wav'):
+                    raise ValueError(f"Invalid sample filename: {filename} (must be .wav)")
+                
+                # Extract audio file to temp location
+                zip_path = f"samples/{filename}"
+                
+                if zip_path not in namelist:
+                    raise ValueError(f"Sample file not found in ZIP: {zip_path}")
+                
+                # Extract to temporary file
+                import tempfile
+                with tempfile.NamedTemporaryFile(suffix=".wav", delete=False) as tmp:
+                    tmp.write(zip_file.read(zip_path))
+                    tmp_path = tmp.name
+                
+                try:
+                    # Add sample to profile
+                    await add_profile_sample(
+                        profile.id,
+                        tmp_path,
+                        reference_text,
+                        db,
+                    )
+                finally:
+                    # Clean up temp file
+                    Path(tmp_path).unlink(missing_ok=True)
+            
+            return profile
+            
+    except zipfile.BadZipFile:
+        raise ValueError("Invalid ZIP file")
+    except json.JSONDecodeError as e:
+        raise ValueError(f"Invalid JSON in archive: {e}")
+    except Exception as e:
+        if isinstance(e, ValueError):
+            raise
+        raise ValueError(f"Error importing profile: {str(e)}")
+
+
+def export_generation_to_zip(generation_id: str, db: Session) -> bytes:
+    """
+    Export a generation to a ZIP archive.
+    
+    Args:
+        generation_id: Generation ID to export
+        db: Database session
+        
+    Returns:
+        ZIP file contents as bytes
+        
+    Raises:
+        ValueError: If generation not found
+    """
+    # Get generation
+    generation = db.query(DBGeneration).filter_by(id=generation_id).first()
+    if not generation:
+        raise ValueError(f"Generation {generation_id} not found")
+    
+    # Get profile info
+    profile = db.query(DBVoiceProfile).filter_by(id=generation.profile_id).first()
+    if not profile:
+        raise ValueError(f"Profile {generation.profile_id} not found")
+    
+    # Get all versions for this generation
+    versions = (
+        db.query(DBGenerationVersion)
+        .filter_by(generation_id=generation_id)
+        .order_by(DBGenerationVersion.created_at)
+        .all()
+    )
+
+    # Create ZIP in memory
+    zip_buffer = io.BytesIO()
+    
+    with zipfile.ZipFile(zip_buffer, 'w', zipfile.ZIP_DEFLATED) as zip_file:
+        # Build version manifest entries
+        version_entries = []
+        for v in versions:
+            v_path = config.resolve_storage_path(v.audio_path)
+            effects_chain = None
+            if v.effects_chain:
+                effects_chain = json.loads(v.effects_chain)
+            version_entries.append({
+                "id": v.id,
+                "label": v.label,
+                "is_default": v.is_default,
+                "effects_chain": effects_chain,
+                "filename": v_path.name,
+            })
+
+        manifest = {
+            "version": "1.0",
+            "generation": {
+                "id": generation.id,
+                "text": generation.text,
+                "language": generation.language,
+                "duration": generation.duration,
+                "seed": generation.seed,
+                "instruct": generation.instruct,
+                "created_at": generation.created_at.isoformat(),
+            },
+            "profile": {
+                "id": profile.id,
+                "name": profile.name,
+                "description": profile.description,
+                "language": profile.language,
+            },
+            "versions": version_entries,
+        }
+        zip_file.writestr("manifest.json", json.dumps(manifest, indent=2))
+        
+        # Add all version audio files
+        for v in versions:
+            v_path = config.resolve_storage_path(v.audio_path)
+            if v_path is not None and v_path.exists():
+                zip_file.write(v_path, f"audio/{v_path.name}")
+
+        # Fallback: if no versions exist, include the generation's main audio
+        if not versions:
+            audio_path = config.resolve_storage_path(generation.audio_path)
+            if audio_path is not None and audio_path.exists():
+                zip_file.write(audio_path, f"audio/{audio_path.name}")
+    
+    zip_buffer.seek(0)
+    return zip_buffer.read()
+
+
+async def import_generation_from_zip(file_bytes: bytes, db: Session) -> dict:
+    """
+    Import a generation from a ZIP archive.
+    
+    Args:
+        file_bytes: ZIP file contents
+        db: Database session
+        
+    Returns:
+        Dictionary with generation ID and profile info
+        
+    Raises:
+        ValueError: If ZIP is invalid or missing required files
+    """
+    from pathlib import Path
+    import tempfile
+    import shutil
+    from datetime import datetime
+    from .. import config
+    
+    zip_buffer = io.BytesIO(file_bytes)
+    
+    try:
+        with zipfile.ZipFile(zip_buffer, 'r') as zip_file:
+            # Validate ZIP structure
+            namelist = zip_file.namelist()
+            
+            if "manifest.json" not in namelist:
+                raise ValueError("ZIP archive missing manifest.json")
+            
+            # Read manifest
+            manifest_data = json.loads(zip_file.read("manifest.json"))
+            
+            if "version" not in manifest_data:
+                raise ValueError("Invalid manifest.json: missing version")
+            
+            if "generation" not in manifest_data:
+                raise ValueError("Invalid manifest.json: missing generation data")
+            
+            generation_data = manifest_data["generation"]
+            profile_data = manifest_data.get("profile", {})
+            
+            # Validate required fields
+            required_fields = ["text", "language", "duration"]
+            for field in required_fields:
+                if field not in generation_data:
+                    raise ValueError(f"Invalid manifest.json: missing generation.{field}")
+            
+            # Find audio file in archive
+            audio_files = [f for f in namelist if f.startswith("audio/") and f.endswith(".wav")]
+            if not audio_files:
+                raise ValueError("No audio file found in ZIP archive")
+            
+            audio_file_path = audio_files[0]
+            
+            # Check if we should match an existing profile or create metadata
+            profile_id = None
+            profile_name = profile_data.get("name", "Unknown Profile")
+            
+            # Try to find matching profile by name
+            if profile_name and profile_name != "Unknown Profile":
+                existing_profile = db.query(DBVoiceProfile).filter_by(name=profile_name).first()
+                if existing_profile:
+                    profile_id = existing_profile.id
+            
+            # If no matching profile, use a placeholder or the first available profile
+            if not profile_id:
+                # Get any profile, or None if no profiles exist
+                any_profile = db.query(DBVoiceProfile).first()
+                if any_profile:
+                    profile_id = any_profile.id
+                    profile_name = any_profile.name
+                else:
+                    raise ValueError("No voice profiles found. Please create a profile before importing generations.")
+            
+            # Extract audio file to temporary location
+            with tempfile.NamedTemporaryFile(suffix=".wav", delete=False) as tmp:
+                tmp.write(zip_file.read(audio_file_path))
+                tmp_path = tmp.name
+            
+            try:
+                # Create generations directory
+                generations_dir = config.get_generations_dir()
+                generations_dir.mkdir(parents=True, exist_ok=True)
+                
+                # Generate new ID for this generation
+                new_generation_id = str(__import__('uuid').uuid4())
+                
+                # Copy audio to generations directory
+                audio_dest = generations_dir / f"{new_generation_id}.wav"
+                shutil.copy(tmp_path, audio_dest)
+                
+                # Create generation record
+                db_generation = DBGeneration(
+                    id=new_generation_id,
+                    profile_id=profile_id,
+                    text=generation_data["text"],
+                    language=generation_data["language"],
+                    audio_path=config.to_storage_path(audio_dest),
+                    duration=generation_data["duration"],
+                    seed=generation_data.get("seed"),
+                    instruct=generation_data.get("instruct"),
+                    created_at=datetime.utcnow(),
+                )
+                
+                db.add(db_generation)
+                db.commit()
+                db.refresh(db_generation)
+                
+                return {
+                    "id": db_generation.id,
+                    "profile_id": profile_id,
+                    "profile_name": profile_name,
+                    "text": db_generation.text,
+                    "message": f"Generation imported successfully (assigned to profile: {profile_name})"
+                }
+                
+            finally:
+                # Clean up temp file
+                Path(tmp_path).unlink(missing_ok=True)
+            
+    except zipfile.BadZipFile:
+        raise ValueError("Invalid ZIP file")
+    except json.JSONDecodeError as e:
+        raise ValueError(f"Invalid JSON in archive: {e}")
+    except Exception as e:
+        if isinstance(e, ValueError):
+            raise
+        raise ValueError(f"Error importing generation: {str(e)}")

backend/services/generation.py

@@ -0,0 +1,263 @@
+"""
+Unified TTS generation orchestration.
+
+Replaces the three near-identical closures (_run_generation, _run_retry,
+_run_regenerate) that lived in main.py with a single ``run_generation()``
+function parameterized by *mode*.
+
+Mode differences:
+  - "generate"   : full pipeline -- save clean version, optionally apply
+                    effects and create a processed version.
+  - "retry"      : re-runs a failed generation with the same seed.
+                    No effects, no version creation.
+  - "regenerate" : re-runs with seed=None for variation.  Creates a new
+                    version with an auto-incremented "take-N" label.
+"""
+
+from __future__ import annotations
+
+import asyncio
+import traceback
+from typing import Literal, Optional
+
+from .. import config
+from . import history, profiles
+from ..database import get_db
+from ..utils.tasks import get_task_manager
+
+
+async def run_generation(
+    *,
+    generation_id: str,
+    profile_id: str,
+    text: str,
+    language: str,
+    engine: str,
+    model_size: str,
+    seed: Optional[int],
+    normalize: bool = False,
+    effects_chain: Optional[list] = None,
+    instruct: Optional[str] = None,
+    mode: Literal["generate", "retry", "regenerate"],
+    max_chunk_chars: Optional[int] = None,
+    crossfade_ms: Optional[int] = None,
+    version_id: Optional[str] = None,
+) -> None:
+    """Execute TTS inference and persist the result.
+
+    This is the single entry point for all background generation work.
+    It is designed to be enqueued via ``services.task_queue.enqueue_generation``.
+    """
+    from ..backends import load_engine_model, get_tts_backend_for_engine, engine_needs_trim
+    from ..utils.chunked_tts import generate_chunked
+    from ..utils.audio import normalize_audio, save_audio, trim_tts_output
+
+    task_manager = get_task_manager()
+    bg_db = next(get_db())
+
+    try:
+        tts_model = get_tts_backend_for_engine(engine)
+
+        if not tts_model.is_loaded():
+            await history.update_generation_status(generation_id, "loading_model", bg_db)
+
+        await load_engine_model(engine, model_size)
+
+        voice_prompt = await profiles.create_voice_prompt_for_profile(
+            profile_id,
+            bg_db,
+            use_cache=True,
+            engine=engine,
+        )
+
+        await history.update_generation_status(generation_id, "generating", bg_db)
+        trim_fn = trim_tts_output if engine_needs_trim(engine) else None
+
+        gen_kwargs: dict = dict(
+            language=language,
+            seed=seed if mode != "regenerate" else None,
+            instruct=instruct,
+            trim_fn=trim_fn,
+        )
+        if max_chunk_chars is not None:
+            gen_kwargs["max_chunk_chars"] = max_chunk_chars
+        if crossfade_ms is not None:
+            gen_kwargs["crossfade_ms"] = crossfade_ms
+
+        audio, sample_rate = await generate_chunked(tts_model, text, voice_prompt, **gen_kwargs)
+
+        # --- Normalize (generate and regenerate always; retry skips) -----
+        if normalize or mode == "regenerate":
+            audio = normalize_audio(audio)
+
+        duration = len(audio) / sample_rate
+
+        # --- Persist audio and update status -----------------------------
+        if mode == "generate":
+            final_path = _save_generate(
+                generation_id=generation_id,
+                audio=audio,
+                sample_rate=sample_rate,
+                effects_chain=effects_chain,
+                save_audio=save_audio,
+                db=bg_db,
+            )
+        elif mode == "retry":
+            final_path = _save_retry(
+                generation_id=generation_id,
+                audio=audio,
+                sample_rate=sample_rate,
+                save_audio=save_audio,
+            )
+        elif mode == "regenerate":
+            final_path = _save_regenerate(
+                generation_id=generation_id,
+                version_id=version_id,
+                audio=audio,
+                sample_rate=sample_rate,
+                save_audio=save_audio,
+                db=bg_db,
+            )
+
+        await history.update_generation_status(
+            generation_id=generation_id,
+            status="completed",
+            db=bg_db,
+            audio_path=final_path,
+            duration=duration,
+        )
+
+    except asyncio.CancelledError:
+        await history.update_generation_status(
+            generation_id=generation_id,
+            status="failed",
+            db=bg_db,
+            error="Generation cancelled",
+        )
+    except Exception as e:
+        traceback.print_exc()
+        await history.update_generation_status(
+            generation_id=generation_id,
+            status="failed",
+            db=bg_db,
+            error=str(e),
+        )
+    finally:
+        task_manager.complete_generation(generation_id)
+        bg_db.close()
+
+
+def _save_generate(
+    *,
+    generation_id: str,
+    audio,
+    sample_rate: int,
+    effects_chain: Optional[list],
+    save_audio,
+    db,
+) -> str:
+    """Save clean version and optionally an effects-processed version.
+
+    Returns the final audio path (processed if effects were applied,
+    otherwise clean).
+    """
+    from . import versions as versions_mod
+
+    clean_audio_path = config.get_generations_dir() / f"{generation_id}.wav"
+    save_audio(audio, str(clean_audio_path), sample_rate)
+
+    has_effects = effects_chain and any(e.get("enabled", True) for e in effects_chain)
+
+    versions_mod.create_version(
+        generation_id=generation_id,
+        label="original",
+        audio_path=config.to_storage_path(clean_audio_path),
+        db=db,
+        effects_chain=None,
+        is_default=not has_effects,
+    )
+
+    final_audio_path = str(clean_audio_path)
+
+    if has_effects:
+        from ..utils.effects import apply_effects, validate_effects_chain
+
+        assert effects_chain is not None
+
+        error_msg = validate_effects_chain(effects_chain)
+        if error_msg:
+            import logging
+            logging.getLogger(__name__).warning("invalid effects chain, skipping: %s", error_msg)
+            versions_mod.set_default_version(
+                versions_mod.list_versions(generation_id, db)[0].id, db
+            )
+        else:
+            processed_audio = apply_effects(audio, sample_rate, effects_chain)
+            processed_path = config.get_generations_dir() / f"{generation_id}_processed.wav"
+            save_audio(processed_audio, str(processed_path), sample_rate)
+            final_audio_path = str(processed_path)
+            versions_mod.create_version(
+                generation_id=generation_id,
+                label="version-2",
+                audio_path=config.to_storage_path(processed_path),
+                db=db,
+                effects_chain=effects_chain,
+                is_default=True,
+            )
+
+    return config.to_storage_path(final_audio_path)
+
+
+def _save_retry(
+    *,
+    generation_id: str,
+    audio,
+    sample_rate: int,
+    save_audio,
+) -> str:
+    """Save retry output -- single file, no versions.
+
+    Returns the audio path.
+    """
+    audio_path = config.get_generations_dir() / f"{generation_id}.wav"
+    save_audio(audio, str(audio_path), sample_rate)
+    return config.to_storage_path(audio_path)
+
+
+def _save_regenerate(
+    *,
+    generation_id: str,
+    version_id: Optional[str],
+    audio,
+    sample_rate: int,
+    save_audio,
+    db,
+) -> str:
+    """Save regeneration output as a new version with auto-label.
+
+    Returns the audio path.
+    """
+    from . import versions as versions_mod
+
+    import uuid as _uuid
+
+    suffix = _uuid.uuid4().hex[:8]
+    audio_path = config.get_generations_dir() / f"{generation_id}_{suffix}.wav"
+    save_audio(audio, str(audio_path), sample_rate)
+
+    # Count via DB query rather than list length to avoid TOCTOU race
+    from ..database import GenerationVersion as DBGenerationVersion
+
+    count = db.query(DBGenerationVersion).filter_by(generation_id=generation_id).count()
+    label = f"take-{count + 1}"
+
+    versions_mod.create_version(
+        generation_id=generation_id,
+        label=label,
+        audio_path=config.to_storage_path(audio_path),
+        db=db,
+        effects_chain=None,
+        is_default=True,
+    )
+
+    return config.to_storage_path(audio_path)

backend/services/history.py

@@ -0,0 +1,368 @@
+"""
+Generation history management module.
+"""
+
+from typing import List, Optional, Tuple
+from datetime import datetime
+import uuid
+import shutil
+from pathlib import Path
+from sqlalchemy.orm import Session
+from sqlalchemy import or_
+
+from ..models import GenerationRequest, GenerationResponse, HistoryQuery, HistoryResponse, HistoryListResponse, GenerationVersionResponse, EffectConfig
+from ..database import Generation as DBGeneration, GenerationVersion as DBGenerationVersion, VoiceProfile as DBVoiceProfile
+from .. import config
+
+
+def _get_versions_for_generation(generation_id: str, db: Session) -> tuple:
+    """Get versions list and active version ID for a generation."""
+    import json
+    versions_rows = (
+        db.query(DBGenerationVersion)
+        .filter_by(generation_id=generation_id)
+        .order_by(DBGenerationVersion.created_at)
+        .all()
+    )
+    if not versions_rows:
+        return None, None
+
+    versions = []
+    active_version_id = None
+    for v in versions_rows:
+        effects_chain = None
+        if v.effects_chain:
+            try:
+                raw = json.loads(v.effects_chain)
+                effects_chain = [EffectConfig(**e) for e in raw]
+            except Exception:
+                pass
+        versions.append(GenerationVersionResponse(
+            id=v.id,
+            generation_id=v.generation_id,
+            label=v.label,
+            audio_path=v.audio_path,
+            effects_chain=effects_chain,
+            is_default=v.is_default,
+            created_at=v.created_at,
+        ))
+        if v.is_default:
+            active_version_id = v.id
+
+    return versions, active_version_id
+
+
+async def create_generation(
+    profile_id: str,
+    text: str,
+    language: str,
+    audio_path: str,
+    duration: float,
+    seed: Optional[int],
+    db: Session,
+    instruct: Optional[str] = None,
+    generation_id: Optional[str] = None,
+    status: str = "completed",
+    engine: Optional[str] = "qwen",
+    model_size: Optional[str] = None,
+) -> GenerationResponse:
+    """
+    Create a new generation history entry.
+
+    Args:
+        profile_id: Profile ID used for generation
+        text: Generated text
+        language: Language code
+        audio_path: Path where audio was saved
+        duration: Audio duration in seconds
+        seed: Random seed used (if any)
+        db: Database session
+        instruct: Natural language instruction used (if any)
+        generation_id: Pre-assigned ID (for async generation flow)
+        status: Generation status (generating, completed, failed)
+        engine: TTS engine used (qwen, luxtts, chatterbox, chatterbox_turbo)
+        model_size: Model size variant (1.7B, 0.6B) — only relevant for qwen
+
+    Returns:
+        Created generation entry
+    """
+    db_generation = DBGeneration(
+        id=generation_id or str(uuid.uuid4()),
+        profile_id=profile_id,
+        text=text,
+        language=language,
+        audio_path=audio_path,
+        duration=duration,
+        seed=seed,
+        instruct=instruct,
+        engine=engine,
+        model_size=model_size,
+        status=status,
+        created_at=datetime.utcnow(),
+    )
+
+    db.add(db_generation)
+    db.commit()
+    db.refresh(db_generation)
+
+    return GenerationResponse.model_validate(db_generation)
+
+
+async def update_generation_status(
+    generation_id: str,
+    status: str,
+    db: Session,
+    audio_path: Optional[str] = None,
+    duration: Optional[float] = None,
+    error: Optional[str] = None,
+) -> Optional[GenerationResponse]:
+    """Update the status of a generation (used by async generation flow)."""
+    generation = db.query(DBGeneration).filter_by(id=generation_id).first()
+    if not generation:
+        return None
+
+    generation.status = status
+    if audio_path is not None:
+        generation.audio_path = audio_path
+    if duration is not None:
+        generation.duration = duration
+    if error is not None:
+        generation.error = error
+
+    db.commit()
+    db.refresh(generation)
+    return GenerationResponse.model_validate(generation)
+
+
+async def get_generation(
+    generation_id: str,
+    db: Session,
+) -> Optional[GenerationResponse]:
+    """
+    Get a generation by ID.
+    
+    Args:
+        generation_id: Generation ID
+        db: Database session
+        
+    Returns:
+        Generation or None if not found
+    """
+    generation = db.query(DBGeneration).filter_by(id=generation_id).first()
+    if not generation:
+        return None
+    
+    return GenerationResponse.model_validate(generation)
+
+
+async def list_generations(
+    query: HistoryQuery,
+    db: Session,
+) -> HistoryListResponse:
+    """
+    List generations with optional filters.
+    
+    Args:
+        query: Query parameters (filters, pagination)
+        db: Database session
+        
+    Returns:
+        HistoryListResponse with items and total count
+    """
+    # Build base query with join to get profile name
+    q = db.query(
+        DBGeneration,
+        DBVoiceProfile.name.label('profile_name')
+    ).join(
+        DBVoiceProfile,
+        DBGeneration.profile_id == DBVoiceProfile.id
+    )
+    
+    # Apply profile filter
+    if query.profile_id:
+        q = q.filter(DBGeneration.profile_id == query.profile_id)
+    
+    # Apply search filter (searches in text content)
+    if query.search:
+        search_pattern = f"%{query.search}%"
+        q = q.filter(DBGeneration.text.like(search_pattern))
+    
+    # Get total count before pagination
+    total_count = q.count()
+    
+    # Apply ordering (newest first)
+    q = q.order_by(DBGeneration.created_at.desc())
+    
+    # Apply pagination
+    q = q.offset(query.offset).limit(query.limit)
+    
+    # Execute query
+    results = q.all()
+    
+    # Convert to HistoryResponse with profile_name
+    items = []
+    for generation, profile_name in results:
+        versions, active_version_id = _get_versions_for_generation(generation.id, db)
+        items.append(HistoryResponse(
+            id=generation.id,
+            profile_id=generation.profile_id,
+            profile_name=profile_name,
+            text=generation.text,
+            language=generation.language,
+            audio_path=generation.audio_path,
+            duration=generation.duration,
+            seed=generation.seed,
+            instruct=generation.instruct,
+            engine=generation.engine or "qwen",
+            model_size=generation.model_size,
+            status=generation.status or "completed",
+            error=generation.error,
+            is_favorited=bool(generation.is_favorited),
+            created_at=generation.created_at,
+            versions=versions,
+            active_version_id=active_version_id,
+        ))
+    
+    return HistoryListResponse(
+        items=items,
+        total=total_count,
+    )
+
+
+async def delete_generation(
+    generation_id: str,
+    db: Session,
+) -> bool:
+    """
+    Delete a generation.
+    
+    Args:
+        generation_id: Generation ID
+        db: Database session
+        
+    Returns:
+        True if deleted, False if not found
+    """
+    generation = db.query(DBGeneration).filter_by(id=generation_id).first()
+    if not generation:
+        return False
+
+    # Delete all version files and records
+    from . import versions as versions_mod
+    versions_mod.delete_versions_for_generation(generation_id, db)
+
+    # Delete main audio file (if not already removed by version cleanup)
+    if generation.audio_path:
+        audio_path = config.resolve_storage_path(generation.audio_path)
+        if audio_path is not None and audio_path.exists():
+            audio_path.unlink()
+
+    # Delete from database
+    db.delete(generation)
+    db.commit()
+    
+    return True
+
+
+async def delete_failed_generations(db: Session) -> int:
+    """
+    Delete every generation whose status is 'failed'.
+
+    Used by the "Clear failed" action in the UI so users can tidy up
+    history after the model wasn't loaded, the app was closed mid-run,
+    or a generation otherwise errored out (see issue #410).
+
+    Returns:
+        Number of generations deleted.
+    """
+    from . import versions as versions_mod
+
+    failed = db.query(DBGeneration).filter(DBGeneration.status == "failed").all()
+    count = 0
+    for generation in failed:
+        # Clean up version files/rows first.
+        versions_mod.delete_versions_for_generation(generation.id, db)
+
+        # Remove the main audio file if it somehow made it to disk.
+        if generation.audio_path:
+            audio_path = config.resolve_storage_path(generation.audio_path)
+            if audio_path is not None and audio_path.exists():
+                try:
+                    audio_path.unlink()
+                except OSError:
+                    # Best-effort cleanup — don't abort the whole sweep
+                    # if a single file can't be removed.
+                    pass
+
+        db.delete(generation)
+        count += 1
+
+    db.commit()
+    return count
+
+
+async def delete_generations_by_profile(
+    profile_id: str,
+    db: Session,
+) -> int:
+    """
+    Delete all generations for a profile.
+    
+    Args:
+        profile_id: Profile ID
+        db: Database session
+        
+    Returns:
+        Number of generations deleted
+    """
+    generations = db.query(DBGeneration).filter_by(profile_id=profile_id).all()
+    
+    count = 0
+    for generation in generations:
+        # Delete associated version files and rows first
+        from . import versions as versions_mod
+        versions_mod.delete_versions_for_generation(generation.id, db)
+
+        # Delete audio file
+        audio_path = config.resolve_storage_path(generation.audio_path)
+        if audio_path is not None and audio_path.exists():
+            audio_path.unlink()
+        
+        # Delete from database
+        db.delete(generation)
+        count += 1
+    
+    db.commit()
+    
+    return count
+
+
+async def get_generation_stats(db: Session) -> dict:
+    """
+    Get generation statistics.
+    
+    Args:
+        db: Database session
+        
+    Returns:
+        Statistics dictionary
+    """
+    from sqlalchemy import func
+    
+    total = db.query(func.count(DBGeneration.id)).scalar()
+    
+    total_duration = db.query(func.sum(DBGeneration.duration)).scalar() or 0
+    
+    # Get generations by profile
+    by_profile = db.query(
+        DBGeneration.profile_id,
+        func.count(DBGeneration.id).label('count')
+    ).group_by(DBGeneration.profile_id).all()
+    
+    return {
+        "total_generations": total,
+        "total_duration_seconds": total_duration,
+        "generations_by_profile": {
+            profile_id: count for profile_id, count in by_profile
+        },
+    }

backend/services/profiles.py

@@ -0,0 +1,686 @@
+"""Voice profile management module."""
+
+import json as _json
+import logging
+import shutil
+import uuid
+from datetime import datetime
+from pathlib import Path
+
+from sqlalchemy import func
+from sqlalchemy.orm import Session
+
+from .. import config
+from ..database import Generation as DBGeneration, ProfileSample as DBProfileSample, VoiceProfile as DBVoiceProfile
+from ..models import (
+    EffectConfig,
+    ProfileSampleResponse,
+    VoiceProfileCreate,
+    VoiceProfileResponse,
+)
+from ..utils.audio import save_audio, validate_and_load_reference_audio
+from ..utils.cache import _get_cache_dir, clear_profile_cache
+from ..utils.images import process_avatar, validate_image
+
+logger = logging.getLogger(__name__)
+
+CLONING_ENGINES = {"qwen", "luxtts", "chatterbox", "chatterbox_turbo", "tada"}
+
+
+def _profile_to_response(
+    profile: DBVoiceProfile,
+    generation_count: int = 0,
+    sample_count: int = 0,
+) -> VoiceProfileResponse:
+    """Convert a DB profile to a VoiceProfileResponse, deserializing effects_chain."""
+    effects_chain = None
+    if profile.effects_chain:
+        try:
+            raw = _json.loads(profile.effects_chain)
+            effects_chain = [EffectConfig(**e) for e in raw]
+        except Exception as e:
+            import logging
+
+            logging.warning(f"Failed to parse effects_chain for profile {profile.id}: {e}")
+    return VoiceProfileResponse(
+        id=profile.id,
+        name=profile.name,
+        description=profile.description,
+        language=profile.language,
+        avatar_path=profile.avatar_path,
+        effects_chain=effects_chain,
+        voice_type=getattr(profile, "voice_type", None) or "cloned",
+        preset_engine=getattr(profile, "preset_engine", None),
+        preset_voice_id=getattr(profile, "preset_voice_id", None),
+        design_prompt=getattr(profile, "design_prompt", None),
+        default_engine=getattr(profile, "default_engine", None),
+        generation_count=generation_count,
+        sample_count=sample_count,
+        created_at=profile.created_at,
+        updated_at=profile.updated_at,
+    )
+
+
+def _get_preset_voice_ids(engine: str) -> set[str]:
+    if engine == "kokoro":
+        from ..backends.kokoro_backend import KOKORO_VOICES
+
+        return {voice_id for voice_id, _name, _gender, _lang in KOKORO_VOICES}
+
+    if engine == "qwen_custom_voice":
+        from ..backends.qwen_custom_voice_backend import QWEN_CUSTOM_VOICES
+
+        return {voice_id for voice_id, _name, _gender, _lang, _desc in QWEN_CUSTOM_VOICES}
+
+    return set()
+
+
+def _validate_profile_fields(
+    *,
+    voice_type: str,
+    preset_engine: str | None,
+    preset_voice_id: str | None,
+    design_prompt: str | None,
+    default_engine: str | None,
+) -> str | None:
+    if voice_type == "preset":
+        if not preset_engine or not preset_voice_id:
+            return "Preset profiles require both preset_engine and preset_voice_id"
+        if default_engine and default_engine != preset_engine:
+            return "Preset profiles must use their preset_engine as default_engine"
+
+        available_voice_ids = _get_preset_voice_ids(preset_engine)
+        if available_voice_ids and preset_voice_id not in available_voice_ids:
+            return f"Preset voice '{preset_voice_id}' is not valid for engine '{preset_engine}'"
+        return None
+
+    if voice_type == "designed":
+        if not design_prompt or not design_prompt.strip():
+            return "Designed profiles require a design_prompt"
+        if preset_engine or preset_voice_id:
+            return "Designed profiles cannot set preset_engine or preset_voice_id"
+        return None
+
+    if preset_engine or preset_voice_id:
+        return "Cloned profiles cannot set preset_engine or preset_voice_id"
+    if design_prompt:
+        return "Cloned profiles cannot set design_prompt"
+    if default_engine and default_engine not in CLONING_ENGINES:
+        return f"Cloned profiles cannot use default engine '{default_engine}'"
+    return None
+
+
+def validate_profile_engine(profile, engine: str) -> None:
+    voice_type = getattr(profile, "voice_type", None) or "cloned"
+
+    if voice_type == "preset":
+        preset_engine = getattr(profile, "preset_engine", None)
+        preset_voice_id = getattr(profile, "preset_voice_id", None)
+        if not preset_engine or not preset_voice_id:
+            raise ValueError(f"Preset profile {profile.id} is missing preset engine metadata")
+        if preset_engine != engine:
+            raise ValueError(
+                f"Preset profile {profile.id} only supports engine '{preset_engine}', not '{engine}'"
+            )
+        return
+
+    if voice_type == "designed":
+        design_prompt = getattr(profile, "design_prompt", None)
+        if not design_prompt or not design_prompt.strip():
+            raise ValueError(f"Designed profile {profile.id} is missing design_prompt")
+        return
+
+    if engine not in CLONING_ENGINES:
+        raise ValueError(f"Engine '{engine}' does not support cloned voice profiles")
+
+
+async def create_profile(
+    data: VoiceProfileCreate,
+    db: Session,
+) -> VoiceProfileResponse:
+    """
+    Create a new voice profile.
+
+    Args:
+        data: Profile creation data
+        db: Database session
+
+    Returns:
+        Created profile
+
+    Raises:
+        ValueError: If a profile with the same name already exists
+    """
+    existing_profile = db.query(DBVoiceProfile).filter_by(name=data.name).first()
+    if existing_profile:
+        raise ValueError(f"A profile with the name '{data.name}' already exists. Please choose a different name.")
+
+    # Auto-set default_engine for preset profiles
+    default_engine = data.default_engine
+    voice_type = data.voice_type or "cloned"
+    if voice_type == "preset" and data.preset_engine and not default_engine:
+        default_engine = data.preset_engine
+
+    validation_error = _validate_profile_fields(
+        voice_type=voice_type,
+        preset_engine=data.preset_engine,
+        preset_voice_id=data.preset_voice_id,
+        design_prompt=data.design_prompt,
+        default_engine=default_engine,
+    )
+    if validation_error:
+        raise ValueError(validation_error)
+
+    db_profile = DBVoiceProfile(
+        id=str(uuid.uuid4()),
+        name=data.name,
+        description=data.description,
+        language=data.language,
+        voice_type=voice_type,
+        preset_engine=data.preset_engine,
+        preset_voice_id=data.preset_voice_id,
+        design_prompt=data.design_prompt,
+        default_engine=default_engine,
+        created_at=datetime.utcnow(),
+        updated_at=datetime.utcnow(),
+    )
+
+    db.add(db_profile)
+    db.commit()
+    db.refresh(db_profile)
+
+    profile_dir = config.get_profiles_dir() / db_profile.id
+    profile_dir.mkdir(parents=True, exist_ok=True)
+
+    return _profile_to_response(db_profile)
+
+
+async def add_profile_sample(
+    profile_id: str,
+    audio_path: str,
+    reference_text: str,
+    db: Session,
+) -> ProfileSampleResponse:
+    """
+    Add a sample to a voice profile.
+
+    Args:
+        profile_id: Profile ID
+        audio_path: Path to temporary audio file
+        reference_text: Transcript of audio
+        db: Database session
+
+    Returns:
+        Created sample
+    """
+    import asyncio
+
+    profile = db.query(DBVoiceProfile).filter_by(id=profile_id).first()
+    if not profile:
+        raise ValueError(f"Profile {profile_id} not found")
+
+    # Validate and load audio in a single pass, off the event loop
+    is_valid, error_msg, audio, sr = await asyncio.to_thread(
+        validate_and_load_reference_audio, audio_path
+    )
+    if not is_valid:
+        raise ValueError(f"Invalid reference audio: {error_msg}")
+
+    sample_id = str(uuid.uuid4())
+    profile_dir = config.get_profiles_dir() / profile_id
+    profile_dir.mkdir(parents=True, exist_ok=True)
+
+    dest_path = profile_dir / f"{sample_id}.wav"
+    await asyncio.to_thread(save_audio, audio, str(dest_path), sr)
+
+    db_sample = DBProfileSample(
+        id=sample_id,
+        profile_id=profile_id,
+        audio_path=config.to_storage_path(dest_path),
+        reference_text=reference_text,
+    )
+
+    db.add(db_sample)
+
+    profile.updated_at = datetime.utcnow()
+
+    db.commit()
+    db.refresh(db_sample)
+
+    # Invalidate combined audio cache for this profile
+    # Since a new sample was added, any cached combined audio is now stale
+    clear_profile_cache(profile_id)
+
+    return ProfileSampleResponse.model_validate(db_sample)
+
+
+async def get_profile(
+    profile_id: str,
+    db: Session,
+) -> VoiceProfileResponse | None:
+    """
+    Get a voice profile by ID.
+
+    Args:
+        profile_id: Profile ID
+        db: Database session
+
+    Returns:
+        Profile or None if not found
+    """
+    profile = db.query(DBVoiceProfile).filter_by(id=profile_id).first()
+    if not profile:
+        return None
+
+    return _profile_to_response(profile)
+
+
+async def get_profile_samples(
+    profile_id: str,
+    db: Session,
+) -> list[ProfileSampleResponse]:
+    """
+    Get all samples for a profile.
+
+    Args:
+        profile_id: Profile ID
+        db: Database session
+
+    Returns:
+        List of samples
+    """
+    samples = db.query(DBProfileSample).filter_by(profile_id=profile_id).all()
+    return [ProfileSampleResponse.model_validate(s) for s in samples]
+
+
+async def list_profiles(db: Session) -> list[VoiceProfileResponse]:
+    """
+    List all voice profiles with generation and sample counts.
+
+    Args:
+        db: Database session
+
+    Returns:
+        List of profiles
+    """
+    profiles = db.query(DBVoiceProfile).order_by(DBVoiceProfile.created_at.desc()).all()
+
+    if not profiles:
+        return []
+
+    # Batch-fetch generation counts
+    gen_counts_rows = (
+        db.query(DBGeneration.profile_id, func.count(DBGeneration.id)).group_by(DBGeneration.profile_id).all()
+    )
+    gen_counts = {row[0]: row[1] for row in gen_counts_rows}
+
+    # Batch-fetch sample counts
+    sample_counts_rows = (
+        db.query(DBProfileSample.profile_id, func.count(DBProfileSample.id)).group_by(DBProfileSample.profile_id).all()
+    )
+    sample_counts = {row[0]: row[1] for row in sample_counts_rows}
+
+    return [
+        _profile_to_response(
+            p,
+            generation_count=gen_counts.get(p.id, 0),
+            sample_count=sample_counts.get(p.id, 0),
+        )
+        for p in profiles
+    ]
+
+
+async def update_profile(
+    profile_id: str,
+    data: VoiceProfileCreate,
+    db: Session,
+) -> VoiceProfileResponse | None:
+    """
+    Update a voice profile.
+
+    Args:
+        profile_id: Profile ID
+        data: Updated profile data
+        db: Database session
+
+    Returns:
+        Updated profile or None if not found
+
+    Raises:
+        ValueError: If a profile with the same name already exists (different profile)
+    """
+    profile = db.query(DBVoiceProfile).filter_by(id=profile_id).first()
+    if not profile:
+        return None
+
+    if profile.name != data.name:
+        existing_profile = db.query(DBVoiceProfile).filter_by(name=data.name).first()
+        if existing_profile:
+            raise ValueError(f"A profile with the name '{data.name}' already exists. Please choose a different name.")
+
+    voice_type = getattr(profile, "voice_type", None) or "cloned"
+    preset_engine = getattr(profile, "preset_engine", None)
+    preset_voice_id = getattr(profile, "preset_voice_id", None)
+    design_prompt = getattr(profile, "design_prompt", None)
+    default_engine = data.default_engine if data.default_engine is not None else getattr(profile, "default_engine", None)
+
+    validation_error = _validate_profile_fields(
+        voice_type=voice_type,
+        preset_engine=preset_engine,
+        preset_voice_id=preset_voice_id,
+        design_prompt=design_prompt,
+        default_engine=default_engine,
+    )
+    if validation_error:
+        raise ValueError(validation_error)
+
+    profile.name = data.name
+    profile.description = data.description
+    profile.language = data.language
+    if data.default_engine is not None:
+        profile.default_engine = data.default_engine or None  # empty string → NULL
+    profile.updated_at = datetime.utcnow()
+
+    db.commit()
+    db.refresh(profile)
+
+    return _profile_to_response(profile)
+
+
+async def delete_profile(
+    profile_id: str,
+    db: Session,
+) -> bool:
+    """
+    Delete a voice profile and all associated data.
+
+    Args:
+        profile_id: Profile ID
+        db: Database session
+
+    Returns:
+        True if deleted, False if not found
+    """
+    profile = db.query(DBVoiceProfile).filter_by(id=profile_id).first()
+    if not profile:
+        return False
+
+    db.query(DBProfileSample).filter_by(profile_id=profile_id).delete()
+
+    db.delete(profile)
+    db.commit()
+
+    profile_dir = config.get_profiles_dir() / profile_id
+    if profile_dir.exists():
+        shutil.rmtree(profile_dir)
+
+    # Clean up combined audio cache files for this profile
+    clear_profile_cache(profile_id)
+
+    return True
+
+
+async def delete_profile_sample(
+    sample_id: str,
+    db: Session,
+) -> bool:
+    """
+    Delete a profile sample.
+
+    Args:
+        sample_id: Sample ID
+        db: Database session
+
+    Returns:
+        True if deleted, False if not found
+    """
+    sample = db.query(DBProfileSample).filter_by(id=sample_id).first()
+    if not sample:
+        return False
+
+    # Store profile_id before deleting
+    profile_id = sample.profile_id
+
+    audio_path = config.resolve_storage_path(sample.audio_path)
+    if audio_path is not None and audio_path.exists():
+        audio_path.unlink()
+
+    db.delete(sample)
+    db.commit()
+
+    # Invalidate combined audio cache for this profile
+    # Since the sample set changed, any cached combined audio is now stale
+    clear_profile_cache(profile_id)
+
+    return True
+
+
+async def update_profile_sample(
+    sample_id: str,
+    reference_text: str,
+    db: Session,
+) -> ProfileSampleResponse | None:
+    """
+    Update a profile sample's reference text.
+
+    Args:
+        sample_id: Sample ID
+        reference_text: Updated reference text
+        db: Database session
+
+    Returns:
+        Updated sample or None if not found
+    """
+    sample = db.query(DBProfileSample).filter_by(id=sample_id).first()
+    if not sample:
+        return None
+
+    # Store profile_id before updating
+    profile_id = sample.profile_id
+
+    sample.reference_text = reference_text
+    db.commit()
+    db.refresh(sample)
+
+    # Invalidate combined audio cache for this profile
+    # Since the reference text changed, cache keys and combined text are now stale
+    clear_profile_cache(profile_id)
+
+    return ProfileSampleResponse.model_validate(sample)
+
+
+async def create_voice_prompt_for_profile(
+    profile_id: str,
+    db: Session,
+    use_cache: bool = True,
+    engine: str = "qwen",
+) -> dict:
+    """
+    Create a voice prompt from a profile.
+
+    For cloned profiles: combines all audio samples into a voice prompt.
+    For preset profiles: returns the engine-specific preset voice reference.
+    For designed profiles: returns the text design prompt (future).
+
+    Args:
+        profile_id: Profile ID
+        db: Database session
+        use_cache: Whether to use cached prompts
+        engine: TTS engine to create prompt for
+
+    Returns:
+        Voice prompt dictionary
+    """
+    from ..backends import get_tts_backend_for_engine
+
+    profile = db.query(DBVoiceProfile).filter_by(id=profile_id).first()
+    if not profile:
+        raise ValueError(f"Profile not found: {profile_id}")
+
+    voice_type = getattr(profile, "voice_type", None) or "cloned"
+    validate_profile_engine(profile, engine)
+
+    # ── Preset profiles: return engine-specific voice reference ──
+    if voice_type == "preset":
+        if not profile.preset_engine or not profile.preset_voice_id:
+            raise ValueError(f"Preset profile {profile_id} is missing preset engine metadata")
+        if profile.preset_engine != engine:
+            raise ValueError(
+                f"Preset profile {profile_id} only supports engine '{profile.preset_engine}', not '{engine}'"
+            )
+        return {
+            "voice_type": "preset",
+            "preset_engine": profile.preset_engine,
+            "preset_voice_id": profile.preset_voice_id,
+        }
+
+    # ── Designed profiles: return text description (future) ──
+    if voice_type == "designed":
+        if not profile.design_prompt or not profile.design_prompt.strip():
+            raise ValueError(f"Designed profile {profile_id} is missing design_prompt")
+        return {
+            "voice_type": "designed",
+            "design_prompt": profile.design_prompt,
+        }
+
+    if engine not in CLONING_ENGINES:
+        raise ValueError(f"Engine '{engine}' does not support cloned voice profiles")
+
+    # ── Cloned profiles: create from audio samples ──
+    samples = db.query(DBProfileSample).filter_by(profile_id=profile_id).all()
+
+    if not samples:
+        raise ValueError(f"No samples found for profile {profile_id}")
+
+    tts_model = get_tts_backend_for_engine(engine)
+
+    if len(samples) == 1:
+        sample = samples[0]
+        sample_audio_path = config.resolve_storage_path(sample.audio_path)
+        if sample_audio_path is None:
+            raise ValueError(f"Sample audio not found for profile {profile_id}")
+        voice_prompt, _ = await tts_model.create_voice_prompt(
+            str(sample_audio_path),
+            sample.reference_text,
+            use_cache=use_cache,
+        )
+        return voice_prompt
+
+    audio_paths = []
+    for sample in samples:
+        sample_audio_path = config.resolve_storage_path(sample.audio_path)
+        if sample_audio_path is None:
+            raise ValueError(f"Sample audio not found for profile {profile_id}")
+        audio_paths.append(str(sample_audio_path))
+    reference_texts = [s.reference_text for s in samples]
+
+    combined_audio, combined_text = await tts_model.combine_voice_prompts(
+        audio_paths,
+        reference_texts,
+    )
+
+    # Save combined audio to cache directory (persistent)
+    # Create a hash of sample IDs to identify this specific combination
+    import hashlib
+
+    sample_ids_str = "-".join(sorted([s.id for s in samples]))
+    combination_hash = hashlib.md5(sample_ids_str.encode()).hexdigest()[:12]
+
+    cache_dir = _get_cache_dir()
+    cache_dir.mkdir(parents=True, exist_ok=True)
+    combined_path = cache_dir / f"combined_{profile_id}_{combination_hash}.wav"
+
+    save_audio(combined_audio, str(combined_path), 24000)
+
+    voice_prompt, _ = await tts_model.create_voice_prompt(
+        str(combined_path),
+        combined_text,
+        use_cache=use_cache,
+    )
+    return voice_prompt
+
+
+async def upload_avatar(
+    profile_id: str,
+    image_path: str,
+    db: Session,
+) -> VoiceProfileResponse:
+    """
+    Upload and process avatar image for a profile.
+
+    Args:
+        profile_id: Profile ID
+        image_path: Path to uploaded image file
+        db: Database session
+
+    Returns:
+        Updated profile
+    """
+    profile = db.query(DBVoiceProfile).filter_by(id=profile_id).first()
+    if not profile:
+        raise ValueError(f"Profile {profile_id} not found")
+
+    is_valid, error_msg = validate_image(image_path)
+    if not is_valid:
+        raise ValueError(error_msg)
+
+    if profile.avatar_path:
+        old_avatar = config.resolve_storage_path(profile.avatar_path)
+        if old_avatar is not None and old_avatar.exists():
+            old_avatar.unlink()
+
+    # Determine file extension from uploaded file
+    from PIL import Image
+
+    with Image.open(image_path) as img:
+        # Normalize JPEG variants (MPO is multi-picture format from some cameras)
+        img_format = img.format
+        if img_format in ("MPO", "JPG"):
+            img_format = "JPEG"
+
+        ext_map = {"PNG": ".png", "JPEG": ".jpg", "WEBP": ".webp"}
+        ext = ext_map.get(img_format, ".png")
+
+    profile_dir = config.get_profiles_dir() / profile_id
+    profile_dir.mkdir(parents=True, exist_ok=True)
+    output_path = profile_dir / f"avatar{ext}"
+
+    process_avatar(image_path, str(output_path))
+
+    profile.avatar_path = config.to_storage_path(output_path)
+    profile.updated_at = datetime.utcnow()
+
+    db.commit()
+    db.refresh(profile)
+
+    return _profile_to_response(profile)
+
+
+async def delete_avatar(
+    profile_id: str,
+    db: Session,
+) -> bool:
+    """
+    Delete avatar image for a profile.
+
+    Args:
+        profile_id: Profile ID
+        db: Database session
+
+    Returns:
+        True if deleted, False if not found or no avatar
+    """
+    profile = db.query(DBVoiceProfile).filter_by(id=profile_id).first()
+    if not profile or not profile.avatar_path:
+        return False
+
+    avatar_path = config.resolve_storage_path(profile.avatar_path)
+    if avatar_path is not None and avatar_path.exists():
+        avatar_path.unlink()
+
+    profile.avatar_path = None
+    profile.updated_at = datetime.utcnow()
+
+    db.commit()
+
+    return True

backend/services/stories.py

@@ -0,0 +1,925 @@
+"""
+Story management module.
+"""
+
+from typing import List, Optional
+from datetime import datetime
+import uuid
+import tempfile
+from pathlib import Path
+from sqlalchemy.orm import Session
+from sqlalchemy import func
+
+from .. import config
+from ..models import (
+    StoryCreate,
+    StoryResponse,
+    StoryDetailResponse,
+    StoryItemDetail,
+    StoryItemCreate,
+    StoryItemBatchUpdate,
+    StoryItemMove,
+    StoryItemTrim,
+    StoryItemSplit,
+    StoryItemVersionUpdate,
+)
+from ..database import (
+    Story as DBStory,
+    StoryItem as DBStoryItem,
+    Generation as DBGeneration,
+    VoiceProfile as DBVoiceProfile,
+)
+from .history import _get_versions_for_generation
+from ..utils.audio import load_audio, save_audio
+import numpy as np
+
+
+def _build_item_detail(
+    item: DBStoryItem,
+    generation: DBGeneration,
+    profile_name: str,
+    db: Session,
+) -> StoryItemDetail:
+    """Build a StoryItemDetail with version info from a story item and its generation."""
+    versions, active_version_id = _get_versions_for_generation(generation.id, db)
+
+    # Resolve the audio path: if version_id is set, use that version's audio
+    audio_path = generation.audio_path
+    if item.version_id and versions:
+        for v in versions:
+            if v.id == item.version_id:
+                audio_path = v.audio_path
+                break
+
+    return StoryItemDetail(
+        id=item.id,
+        story_id=item.story_id,
+        generation_id=item.generation_id,
+        version_id=getattr(item, "version_id", None),
+        start_time_ms=item.start_time_ms,
+        track=item.track,
+        trim_start_ms=getattr(item, "trim_start_ms", 0),
+        trim_end_ms=getattr(item, "trim_end_ms", 0),
+        created_at=item.created_at,
+        profile_id=generation.profile_id,
+        profile_name=profile_name,
+        text=generation.text,
+        language=generation.language,
+        audio_path=audio_path,
+        duration=generation.duration,
+        seed=generation.seed,
+        instruct=generation.instruct,
+        generation_created_at=generation.created_at,
+        versions=versions,
+        active_version_id=active_version_id,
+    )
+
+
+async def create_story(
+    data: StoryCreate,
+    db: Session,
+) -> StoryResponse:
+    """
+    Create a new story.
+
+    Args:
+        data: Story creation data
+        db: Database session
+
+    Returns:
+        Created story
+    """
+    db_story = DBStory(
+        id=str(uuid.uuid4()),
+        name=data.name,
+        description=data.description,
+        created_at=datetime.utcnow(),
+        updated_at=datetime.utcnow(),
+    )
+
+    db.add(db_story)
+    db.commit()
+    db.refresh(db_story)
+
+    item_count = db.query(func.count(DBStoryItem.id)).filter(DBStoryItem.story_id == db_story.id).scalar()
+
+    response = StoryResponse.model_validate(db_story)
+    response.item_count = item_count
+    return response
+
+
+async def list_stories(
+    db: Session,
+) -> List[StoryResponse]:
+    """
+    List all stories.
+
+    Args:
+        db: Database session
+
+    Returns:
+        List of stories with item counts
+    """
+    stories = db.query(DBStory).order_by(DBStory.updated_at.desc()).all()
+
+    result = []
+    for story in stories:
+        item_count = db.query(func.count(DBStoryItem.id)).filter(DBStoryItem.story_id == story.id).scalar()
+
+        response = StoryResponse.model_validate(story)
+        response.item_count = item_count
+        result.append(response)
+
+    return result
+
+
+async def get_story(
+    story_id: str,
+    db: Session,
+) -> Optional[StoryDetailResponse]:
+    """
+    Get a story with all its items.
+
+    Args:
+        story_id: Story ID
+        db: Database session
+
+    Returns:
+        Story with items or None if not found
+    """
+    story = db.query(DBStory).filter_by(id=story_id).first()
+    if not story:
+        return None
+
+    items = (
+        db.query(DBStoryItem, DBGeneration, DBVoiceProfile.name.label("profile_name"))
+        .join(DBGeneration, DBStoryItem.generation_id == DBGeneration.id)
+        .join(DBVoiceProfile, DBGeneration.profile_id == DBVoiceProfile.id)
+        .filter(DBStoryItem.story_id == story_id)
+        .order_by(DBStoryItem.start_time_ms)
+        .all()
+    )
+
+    item_details = []
+    for item, generation, profile_name in items:
+        item_details.append(_build_item_detail(item, generation, profile_name, db))
+
+    response = StoryDetailResponse.model_validate(story)
+    response.items = item_details
+    return response
+
+
+async def update_story(
+    story_id: str,
+    data: StoryCreate,
+    db: Session,
+) -> Optional[StoryResponse]:
+    """
+    Update a story.
+
+    Args:
+        story_id: Story ID
+        data: Update data
+        db: Database session
+
+    Returns:
+        Updated story or None if not found
+    """
+    story = db.query(DBStory).filter_by(id=story_id).first()
+    if not story:
+        return None
+
+    story.name = data.name
+    story.description = data.description
+    story.updated_at = datetime.utcnow()
+
+    db.commit()
+    db.refresh(story)
+
+    item_count = db.query(func.count(DBStoryItem.id)).filter(DBStoryItem.story_id == story.id).scalar()
+
+    response = StoryResponse.model_validate(story)
+    response.item_count = item_count
+    return response
+
+
+async def delete_story(
+    story_id: str,
+    db: Session,
+) -> bool:
+    """
+    Delete a story and all its items.
+
+    Args:
+        story_id: Story ID
+        db: Database session
+
+    Returns:
+        True if deleted, False if not found
+    """
+    story = db.query(DBStory).filter_by(id=story_id).first()
+    if not story:
+        return False
+
+    # Delete all items
+    db.query(DBStoryItem).filter_by(story_id=story_id).delete()
+
+    # Delete story
+    db.delete(story)
+    db.commit()
+
+    return True
+
+
+async def add_item_to_story(
+    story_id: str,
+    data: StoryItemCreate,
+    db: Session,
+) -> Optional[StoryItemDetail]:
+    """
+    Add a generation to a story.
+
+    Args:
+        story_id: Story ID
+        data: Item creation data
+        db: Database session
+
+    Returns:
+        Created item detail or None if story/generation not found
+    """
+    # Verify story exists
+    story = db.query(DBStory).filter_by(id=story_id).first()
+    if not story:
+        return None
+
+    # Verify generation exists
+    generation = db.query(DBGeneration).filter_by(id=data.generation_id).first()
+    if not generation:
+        return None
+
+    # Check if generation is already in story
+    existing = db.query(DBStoryItem).filter_by(story_id=story_id, generation_id=data.generation_id).first()
+    if existing:
+        # Return existing item
+        profile = db.query(DBVoiceProfile).filter_by(id=generation.profile_id).first()
+        return _build_item_detail(existing, generation, profile.name if profile else "Unknown", db)
+
+    # Get track from data or default to 0
+    track = data.track if data.track is not None else 0
+
+    # Calculate start_time_ms if not provided
+    if data.start_time_ms is not None:
+        start_time_ms = data.start_time_ms
+    else:
+        existing_items = (
+            db.query(DBStoryItem, DBGeneration)
+            .join(DBGeneration, DBStoryItem.generation_id == DBGeneration.id)
+            .filter(
+                DBStoryItem.story_id == story_id,
+                DBStoryItem.track == track,
+            )
+            .all()
+        )
+
+        if not existing_items:
+            start_time_ms = 0
+        else:
+            max_end_time_ms = 0
+            for item, gen in existing_items:
+                item_end_ms = item.start_time_ms + int(gen.duration * 1000)
+                max_end_time_ms = max(max_end_time_ms, item_end_ms)
+
+            # Add 200ms gap after the last item
+            start_time_ms = max_end_time_ms + 200
+
+    # Create item
+    item = DBStoryItem(
+        id=str(uuid.uuid4()),
+        story_id=story_id,
+        generation_id=data.generation_id,
+        start_time_ms=start_time_ms,
+        track=track,
+        created_at=datetime.utcnow(),
+    )
+
+    db.add(item)
+
+    # Update story updated_at
+    story.updated_at = datetime.utcnow()
+
+    db.commit()
+    db.refresh(item)
+
+    # Get profile name
+    profile = db.query(DBVoiceProfile).filter_by(id=generation.profile_id).first()
+
+    return _build_item_detail(item, generation, profile.name if profile else "Unknown", db)
+
+
+async def move_story_item(
+    story_id: str,
+    item_id: str,
+    data: StoryItemMove,
+    db: Session,
+) -> Optional[StoryItemDetail]:
+    """
+    Move a story item (update position and/or track).
+
+    Args:
+        story_id: Story ID
+        item_id: Story item ID
+        data: New position and track data
+        db: Database session
+
+    Returns:
+        Updated item detail or None if not found
+    """
+    # Get the item
+    item = (
+        db.query(DBStoryItem)
+        .filter_by(
+            id=item_id,
+            story_id=story_id,
+        )
+        .first()
+    )
+    if not item:
+        return None
+
+    # Get the generation
+    generation = db.query(DBGeneration).filter_by(id=item.generation_id).first()
+    if not generation:
+        return None
+
+    # Update position and track
+    item.start_time_ms = data.start_time_ms
+    item.track = data.track
+
+    # Update story updated_at
+    story = db.query(DBStory).filter_by(id=story_id).first()
+    if story:
+        story.updated_at = datetime.utcnow()
+
+    db.commit()
+    db.refresh(item)
+
+    # Get profile name
+    profile = db.query(DBVoiceProfile).filter_by(id=generation.profile_id).first()
+
+    return _build_item_detail(item, generation, profile.name if profile else "Unknown", db)
+
+
+async def remove_item_from_story(
+    story_id: str,
+    item_id: str,
+    db: Session,
+) -> bool:
+    """
+    Remove a story item from a story.
+
+    Args:
+        story_id: Story ID
+        item_id: Story item ID to remove
+        db: Database session
+
+    Returns:
+        True if removed, False if not found
+    """
+    item = (
+        db.query(DBStoryItem)
+        .filter_by(
+            id=item_id,
+            story_id=story_id,
+        )
+        .first()
+    )
+    if not item:
+        return False
+
+    # Delete item
+    db.delete(item)
+
+    # Update story updated_at
+    story = db.query(DBStory).filter_by(id=story_id).first()
+    if story:
+        story.updated_at = datetime.utcnow()
+
+    db.commit()
+    return True
+
+
+async def trim_story_item(
+    story_id: str,
+    item_id: str,
+    data: StoryItemTrim,
+    db: Session,
+) -> Optional[StoryItemDetail]:
+    """
+    Trim a story item (update trim_start_ms and trim_end_ms).
+
+    Args:
+        story_id: Story ID
+        item_id: Story item ID
+        data: Trim data (trim_start_ms, trim_end_ms)
+        db: Database session
+
+    Returns:
+        Updated item detail or None if not found
+    """
+    # Get the item
+    item = (
+        db.query(DBStoryItem)
+        .filter_by(
+            id=item_id,
+            story_id=story_id,
+        )
+        .first()
+    )
+    if not item:
+        return None
+
+    # Get the generation
+    generation = db.query(DBGeneration).filter_by(id=item.generation_id).first()
+    if not generation:
+        return None
+
+    # Validate trim values don't exceed duration
+    max_duration_ms = int(generation.duration * 1000)
+    if data.trim_start_ms + data.trim_end_ms >= max_duration_ms:
+        return None  # Invalid trim - would result in zero or negative duration
+
+    # Update trim values
+    item.trim_start_ms = data.trim_start_ms
+    item.trim_end_ms = data.trim_end_ms
+
+    # Update story updated_at
+    story = db.query(DBStory).filter_by(id=story_id).first()
+    if story:
+        story.updated_at = datetime.utcnow()
+
+    db.commit()
+    db.refresh(item)
+
+    # Get profile name
+    profile = db.query(DBVoiceProfile).filter_by(id=generation.profile_id).first()
+
+    return _build_item_detail(item, generation, profile.name if profile else "Unknown", db)
+
+
+async def split_story_item(
+    story_id: str,
+    item_id: str,
+    data: StoryItemSplit,
+    db: Session,
+) -> Optional[List[StoryItemDetail]]:
+    """
+    Split a story item at a given time, creating two clips.
+
+    Args:
+        story_id: Story ID
+        item_id: Story item ID to split
+        data: Split data (split_time_ms - time within clip to split at)
+        db: Database session
+
+    Returns:
+        List of two updated item details (original and new) or None if not found/invalid
+    """
+    # Get the item with a row lock to prevent concurrent splits on the
+    # same clip (e.g. from rapid double-clicks racing each other).
+    item = (
+        db.query(DBStoryItem)
+        .filter_by(
+            id=item_id,
+            story_id=story_id,
+        )
+        .with_for_update()
+        .first()
+    )
+    if not item:
+        return None
+
+    # Get the generation
+    generation = db.query(DBGeneration).filter_by(id=item.generation_id).first()
+    if not generation:
+        return None
+
+    # Calculate effective duration and validate split point
+    current_trim_start = getattr(item, "trim_start_ms", 0)
+    current_trim_end = getattr(item, "trim_end_ms", 0)
+    original_duration_ms = int(generation.duration * 1000)
+    effective_duration_ms = original_duration_ms - current_trim_start - current_trim_end
+
+    # Validate split_time_ms is within the effective duration
+    if data.split_time_ms <= 0 or data.split_time_ms >= effective_duration_ms:
+        return None  # Invalid split point
+
+    # Calculate the absolute time in the original audio where we're splitting
+    absolute_split_ms = current_trim_start + data.split_time_ms
+
+    # Update original clip: trim from the end
+    item.trim_end_ms = original_duration_ms - absolute_split_ms
+
+    # Create new clip: starts after the split, trimmed from the start
+    new_item = DBStoryItem(
+        id=str(uuid.uuid4()),
+        story_id=story_id,
+        generation_id=item.generation_id,  # Same generation, different trim
+        version_id=getattr(item, "version_id", None),  # Preserve pinned version
+        start_time_ms=item.start_time_ms + data.split_time_ms,
+        track=item.track,
+        trim_start_ms=absolute_split_ms,
+        trim_end_ms=current_trim_end,
+        created_at=datetime.utcnow(),
+    )
+
+    db.add(new_item)
+
+    # Update story updated_at
+    story = db.query(DBStory).filter_by(id=story_id).first()
+    if story:
+        story.updated_at = datetime.utcnow()
+
+    db.commit()
+    db.refresh(item)
+    db.refresh(new_item)
+
+    # Get profile name
+    profile = db.query(DBVoiceProfile).filter_by(id=generation.profile_id).first()
+    profile_name = profile.name if profile else "Unknown"
+
+    return [
+        _build_item_detail(item, generation, profile_name, db),
+        _build_item_detail(new_item, generation, profile_name, db),
+    ]
+
+
+async def duplicate_story_item(
+    story_id: str,
+    item_id: str,
+    db: Session,
+) -> Optional[StoryItemDetail]:
+    """
+    Duplicate a story item, creating a copy with all properties.
+
+    Args:
+        story_id: Story ID
+        item_id: Story item ID to duplicate
+        db: Database session
+
+    Returns:
+        New item detail or None if not found
+    """
+    # Get the original item
+    original_item = (
+        db.query(DBStoryItem)
+        .filter_by(
+            id=item_id,
+            story_id=story_id,
+        )
+        .first()
+    )
+    if not original_item:
+        return None
+
+    # Get the generation
+    generation = db.query(DBGeneration).filter_by(id=original_item.generation_id).first()
+    if not generation:
+        return None
+
+    # Calculate effective duration
+    current_trim_start = getattr(original_item, "trim_start_ms", 0)
+    current_trim_end = getattr(original_item, "trim_end_ms", 0)
+    original_duration_ms = int(generation.duration * 1000)
+    effective_duration_ms = original_duration_ms - current_trim_start - current_trim_end
+
+    # Create duplicate item - place it right after the original
+    new_item = DBStoryItem(
+        id=str(uuid.uuid4()),
+        story_id=story_id,
+        generation_id=original_item.generation_id,  # Same generation as original
+        version_id=getattr(original_item, "version_id", None),  # Preserve pinned version
+        start_time_ms=original_item.start_time_ms + effective_duration_ms + 200,  # 200ms gap
+        track=original_item.track,
+        trim_start_ms=current_trim_start,
+        trim_end_ms=current_trim_end,
+        created_at=datetime.utcnow(),
+    )
+
+    db.add(new_item)
+
+    # Update story updated_at
+    story = db.query(DBStory).filter_by(id=story_id).first()
+    if story:
+        story.updated_at = datetime.utcnow()
+
+    db.commit()
+    db.refresh(new_item)
+
+    # Get profile name
+    profile = db.query(DBVoiceProfile).filter_by(id=generation.profile_id).first()
+
+    return _build_item_detail(new_item, generation, profile.name if profile else "Unknown", db)
+
+
+async def update_story_item_times(
+    story_id: str,
+    data: StoryItemBatchUpdate,
+    db: Session,
+) -> bool:
+    """
+    Update story item timecodes.
+
+    Args:
+        story_id: Story ID
+        data: Batch update data with timecodes
+        db: Database session
+
+    Returns:
+        True if updated, False if story not found or invalid
+    """
+    story = db.query(DBStory).filter_by(id=story_id).first()
+    if not story:
+        return False
+
+    # Get all items for this story
+    items = db.query(DBStoryItem).filter_by(story_id=story_id).all()
+    item_map = {item.generation_id: item for item in items}
+
+    # Verify all generation IDs belong to this story and update timecodes
+    for update in data.updates:
+        if update.generation_id not in item_map:
+            return False
+        item_map[update.generation_id].start_time_ms = update.start_time_ms
+
+    # Update story updated_at
+    story.updated_at = datetime.utcnow()
+
+    db.commit()
+    return True
+
+
+async def reorder_story_items(
+    story_id: str,
+    generation_ids: List[str],
+    db: Session,
+    gap_ms: int = 200,
+) -> Optional[List[StoryItemDetail]]:
+    """
+    Reorder story items and recalculate timecodes.
+
+    Args:
+        story_id: Story ID
+        generation_ids: List of generation IDs in the desired order
+        db: Database session
+        gap_ms: Gap in milliseconds between items (default 200ms)
+
+    Returns:
+        Updated list of story items with new timecodes, or None if invalid
+    """
+    story = db.query(DBStory).filter_by(id=story_id).first()
+    if not story:
+        return None
+
+    # Get all items for this story with their generation data
+    items_with_gen = (
+        db.query(DBStoryItem, DBGeneration, DBVoiceProfile.name.label("profile_name"))
+        .join(DBGeneration, DBStoryItem.generation_id == DBGeneration.id)
+        .join(DBVoiceProfile, DBGeneration.profile_id == DBVoiceProfile.id)
+        .filter(DBStoryItem.story_id == story_id)
+        .all()
+    )
+
+    # Create maps for quick lookup
+    item_map = {item.generation_id: (item, gen, profile_name) for item, gen, profile_name in items_with_gen}
+
+    # Verify all generation IDs belong to this story
+    if set(generation_ids) != set(item_map.keys()):
+        return None
+
+    # Recalculate timecodes based on new order
+    current_time_ms = 0
+    updated_items = []
+
+    for gen_id in generation_ids:
+        item, generation, profile_name = item_map[gen_id]
+
+        # Update the item's start time
+        item.start_time_ms = current_time_ms
+
+        # Calculate the duration in ms
+        duration_ms = int(generation.duration * 1000)
+
+        # Move to next position (current end + gap)
+        current_time_ms += duration_ms + gap_ms
+
+        # Build the response item
+        updated_items.append(_build_item_detail(item, generation, profile_name, db))
+
+    # Update story updated_at
+    story.updated_at = datetime.utcnow()
+
+    db.commit()
+    return updated_items
+
+
+async def set_story_item_version(
+    story_id: str,
+    item_id: str,
+    data: StoryItemVersionUpdate,
+    db: Session,
+) -> Optional[StoryItemDetail]:
+    """
+    Pin a story item to a specific generation version.
+
+    Args:
+        story_id: Story ID
+        item_id: Story item ID
+        data: Version update data (version_id or null for default)
+        db: Database session
+
+    Returns:
+        Updated item detail or None if not found
+    """
+    item = (
+        db.query(DBStoryItem)
+        .filter_by(
+            id=item_id,
+            story_id=story_id,
+        )
+        .first()
+    )
+    if not item:
+        return None
+
+    generation = db.query(DBGeneration).filter_by(id=item.generation_id).first()
+    if not generation:
+        return None
+
+    # Validate version_id belongs to this generation if provided
+    if data.version_id:
+        from ..database import GenerationVersion as DBGenerationVersion
+
+        version = (
+            db.query(DBGenerationVersion)
+            .filter_by(
+                id=data.version_id,
+                generation_id=item.generation_id,
+            )
+            .first()
+        )
+        if not version:
+            return None
+
+    item.version_id = data.version_id
+
+    # Update story updated_at
+    story = db.query(DBStory).filter_by(id=story_id).first()
+    if story:
+        story.updated_at = datetime.utcnow()
+
+    db.commit()
+    db.refresh(item)
+
+    profile = db.query(DBVoiceProfile).filter_by(id=generation.profile_id).first()
+
+    return _build_item_detail(item, generation, profile.name if profile else "Unknown", db)
+
+
+async def export_story_audio(
+    story_id: str,
+    db: Session,
+) -> Optional[bytes]:
+    """
+    Export story as single mixed audio file with timecode-based mixing.
+
+    Args:
+        story_id: Story ID
+        db: Database session
+
+    Returns:
+        Audio file bytes or None if story not found
+    """
+    story = db.query(DBStory).filter_by(id=story_id).first()
+    if not story:
+        return None
+
+    # Get all items ordered by start_time_ms
+    items = (
+        db.query(DBStoryItem, DBGeneration)
+        .join(DBGeneration, DBStoryItem.generation_id == DBGeneration.id)
+        .filter(DBStoryItem.story_id == story_id)
+        .order_by(DBStoryItem.start_time_ms)
+        .all()
+    )
+
+    if not items:
+        return None
+
+    # Load all audio files and calculate total duration
+    audio_data = []
+    sample_rate = 24000  # Default sample rate
+
+    for item, generation in items:
+        # Resolve audio path: use pinned version if set, otherwise generation default
+        resolved_audio_path = generation.audio_path
+        if getattr(item, "version_id", None):
+            from ..database import GenerationVersion as DBGenerationVersion
+
+            version = db.query(DBGenerationVersion).filter_by(id=item.version_id).first()
+            if version:
+                resolved_audio_path = version.audio_path
+
+        audio_path = config.resolve_storage_path(resolved_audio_path)
+        if audio_path is None or not audio_path.exists():
+            continue
+
+        try:
+            audio, sr = load_audio(str(audio_path), sample_rate=sample_rate)
+            sample_rate = sr  # Use actual sample rate from first file
+
+            # Get trim values
+            trim_start_ms = getattr(item, "trim_start_ms", 0)
+            trim_end_ms = getattr(item, "trim_end_ms", 0)
+
+            # Calculate effective duration
+            original_duration_ms = int(generation.duration * 1000)
+            effective_duration_ms = original_duration_ms - trim_start_ms - trim_end_ms
+
+            # Slice audio based on trim values
+            trim_start_sample = int((trim_start_ms / 1000.0) * sample_rate)
+            trim_end_sample = int((trim_end_ms / 1000.0) * sample_rate)
+
+            # Extract the trimmed portion
+            if trim_end_ms > 0:
+                trimmed_audio = (
+                    audio[trim_start_sample:-trim_end_sample] if trim_end_sample > 0 else audio[trim_start_sample:]
+                )
+            else:
+                trimmed_audio = audio[trim_start_sample:]
+
+            # Store audio with its timecode info
+            start_time_ms = item.start_time_ms
+
+            audio_data.append(
+                {
+                    "audio": trimmed_audio,
+                    "start_time_ms": start_time_ms,
+                    "duration_ms": effective_duration_ms,
+                }
+            )
+        except Exception:
+            # Skip files that can't be loaded
+            continue
+
+    if not audio_data:
+        return None
+
+    # Calculate total duration: max(start_time_ms + duration_ms)
+    max_end_time_ms = max((data["start_time_ms"] + data["duration_ms"] for data in audio_data), default=0)
+
+    # Convert to samples
+    total_samples = int((max_end_time_ms / 1000.0) * sample_rate)
+
+    # Create output buffer initialized to zeros
+    final_audio = np.zeros(total_samples, dtype=np.float32)
+
+    # Mix each audio segment at its timecode position
+    for data in audio_data:
+        audio = data["audio"]
+        start_time_ms = data["start_time_ms"]
+
+        # Calculate start sample index
+        start_sample = int((start_time_ms / 1000.0) * sample_rate)
+
+        # Ensure we don't exceed buffer bounds
+        audio_length = len(audio)
+        end_sample = min(start_sample + audio_length, total_samples)
+
+        if start_sample < total_samples:
+            # Trim audio if it extends beyond buffer
+            audio_to_mix = audio[: end_sample - start_sample]
+
+            # Mix: add audio to existing buffer (overlapping audio will sum)
+            # Normalize to prevent clipping (simple approach: divide by max)
+            final_audio[start_sample:end_sample] += audio_to_mix
+
+    # Normalize to prevent clipping
+    max_val = np.abs(final_audio).max()
+    if max_val > 1.0:
+        final_audio = final_audio / max_val
+
+    # Save to temporary file
+    with tempfile.NamedTemporaryFile(suffix=".wav", delete=False) as tmp:
+        tmp_path = tmp.name
+
+    try:
+        save_audio(final_audio, tmp_path, sample_rate)
+
+        # Read file bytes
+        with open(tmp_path, "rb") as f:
+            audio_bytes = f.read()
+
+        return audio_bytes
+    finally:
+        # Clean up temp file
+        Path(tmp_path).unlink(missing_ok=True)

backend/services/task_queue.py

@@ -0,0 +1,108 @@
+"""
+Serial generation queue — ensures only one TTS inference runs at a time
+to avoid GPU contention.
+"""
+
+import asyncio
+import traceback
+from dataclasses import dataclass
+from typing import Coroutine, Literal
+
+# Keep references to fire-and-forget background tasks to prevent GC
+_background_tasks: set = set()
+
+
+@dataclass
+class GenerationJob:
+    """Queued generation work plus the generation ID it belongs to."""
+
+    generation_id: str
+    coro: Coroutine
+
+
+# Generation queue — serializes TTS inference to avoid GPU contention
+_generation_queue: asyncio.Queue = None  # type: ignore  # initialized at startup
+_generation_worker_task: asyncio.Task | None = None
+_queued_generation_ids: set[str] = set()
+_running_generation_tasks: dict[str, asyncio.Task] = {}
+_cancelled_generation_ids: set[str] = set()
+
+
+def create_background_task(coro) -> asyncio.Task:
+    """Create a background task and prevent it from being garbage collected."""
+    task = asyncio.create_task(coro)
+    _background_tasks.add(task)
+    task.add_done_callback(_background_tasks.discard)
+    return task
+
+
+async def _generation_worker():
+    """Worker that processes generation tasks one at a time."""
+    while True:
+        job = await _generation_queue.get()
+        try:
+            if job.generation_id in _cancelled_generation_ids:
+                _cancelled_generation_ids.discard(job.generation_id)
+                job.coro.close()
+                continue
+
+            task = asyncio.create_task(job.coro)
+            _running_generation_tasks[job.generation_id] = task
+            _queued_generation_ids.discard(job.generation_id)
+            try:
+                await task
+            except asyncio.CancelledError:
+                if not task.cancelled():
+                    raise
+        except Exception:
+            traceback.print_exc()
+        finally:
+            _running_generation_tasks.pop(job.generation_id, None)
+            _queued_generation_ids.discard(job.generation_id)
+            _generation_queue.task_done()
+
+
+def enqueue_generation(generation_id: str, coro):
+    """Add a generation coroutine to the serial queue."""
+    if _generation_queue is None:
+        raise RuntimeError("Generation queue has not been initialized")
+
+    _queued_generation_ids.add(generation_id)
+    _generation_queue.put_nowait(GenerationJob(generation_id=generation_id, coro=coro))
+
+
+def cancel_generation(generation_id: str) -> Literal["queued", "running"] | None:
+    """Cancel a queued or running generation if it is still active."""
+    running_task = _running_generation_tasks.get(generation_id)
+    if running_task is not None:
+        running_task.cancel()
+        return "running"
+
+    if generation_id in _queued_generation_ids:
+        _queued_generation_ids.discard(generation_id)
+        _cancelled_generation_ids.add(generation_id)
+        return "queued"
+
+    return None
+
+
+def init_queue(force: bool = False):
+    """Initialize the generation queue and start the worker.
+
+    Must be called once during application startup (inside a running event loop).
+    """
+    global _generation_queue, _generation_worker_task
+    global _queued_generation_ids, _running_generation_tasks, _cancelled_generation_ids
+
+    if _generation_worker_task is not None and not _generation_worker_task.done():
+        if not force:
+            return
+        _generation_worker_task.cancel()
+        for task in list(_running_generation_tasks.values()):
+            task.cancel()
+
+    _generation_queue = asyncio.Queue()
+    _queued_generation_ids = set()
+    _running_generation_tasks = {}
+    _cancelled_generation_ids = set()
+    _generation_worker_task = create_background_task(_generation_worker())

backend/services/transcribe.py

@@ -0,0 +1,22 @@
+"""
+STT (Speech-to-Text) module - delegates to backend abstraction layer.
+"""
+
+from typing import Optional
+from ..backends import get_stt_backend, STTBackend
+
+
+def get_whisper_model() -> STTBackend:
+    """
+    Get STT backend instance (MLX or PyTorch based on platform).
+    
+    Returns:
+        STT backend instance
+    """
+    return get_stt_backend()
+
+
+def unload_whisper_model():
+    """Unload Whisper model to free memory."""
+    backend = get_stt_backend()
+    backend.unload_model()

backend/services/tts.py

@@ -0,0 +1,34 @@
+"""
+TTS inference module - delegates to backend abstraction layer.
+"""
+
+from typing import Optional
+import numpy as np
+import io
+import soundfile as sf
+
+from ..backends import get_tts_backend, TTSBackend
+
+
+def get_tts_model() -> TTSBackend:
+    """
+    Get TTS backend instance (MLX or PyTorch based on platform).
+    
+    Returns:
+        TTS backend instance
+    """
+    return get_tts_backend()
+
+
+def unload_tts_model():
+    """Unload TTS model to free memory."""
+    backend = get_tts_backend()
+    backend.unload_model()
+
+
+def audio_to_wav_bytes(audio: np.ndarray, sample_rate: int) -> bytes:
+    """Convert audio array to WAV bytes."""
+    buffer = io.BytesIO()
+    sf.write(buffer, audio, sample_rate, format="WAV")
+    buffer.seek(0)
+    return buffer.read()

backend/services/versions.py

@@ -0,0 +1,211 @@
+"""
+Generation versions management module.
+
+Each generation can have multiple audio versions: a clean (unprocessed)
+version and any number of processed versions with different effects chains.
+"""
+
+from __future__ import annotations
+
+import json
+import uuid
+from pathlib import Path
+from typing import List, Optional
+
+from sqlalchemy.orm import Session
+
+from ..database import (
+    GenerationVersion as DBGenerationVersion,
+    Generation as DBGeneration,
+)
+from ..models import GenerationVersionResponse, EffectConfig
+from .. import config
+
+
+def _version_response(v: DBGenerationVersion) -> GenerationVersionResponse:
+    """Convert a DB version row to a Pydantic response."""
+    effects_chain = None
+    if v.effects_chain:
+        raw = json.loads(v.effects_chain)
+        effects_chain = [EffectConfig(**e) for e in raw]
+    return GenerationVersionResponse(
+        id=v.id,
+        generation_id=v.generation_id,
+        label=v.label,
+        audio_path=v.audio_path,
+        effects_chain=effects_chain,
+        source_version_id=v.source_version_id,
+        is_default=v.is_default,
+        created_at=v.created_at,
+    )
+
+
+def list_versions(generation_id: str, db: Session) -> List[GenerationVersionResponse]:
+    """List all versions for a generation."""
+    versions = (
+        db.query(DBGenerationVersion)
+        .filter_by(generation_id=generation_id)
+        .order_by(DBGenerationVersion.created_at)
+        .all()
+    )
+    return [_version_response(v) for v in versions]
+
+
+def get_version(version_id: str, db: Session) -> Optional[GenerationVersionResponse]:
+    """Get a specific version by ID."""
+    v = db.query(DBGenerationVersion).filter_by(id=version_id).first()
+    if not v:
+        return None
+    return _version_response(v)
+
+
+def get_default_version(generation_id: str, db: Session) -> Optional[GenerationVersionResponse]:
+    """Get the default version for a generation."""
+    v = (
+        db.query(DBGenerationVersion)
+        .filter_by(generation_id=generation_id, is_default=True)
+        .first()
+    )
+    if not v:
+        # Fallback: return the first version
+        v = (
+            db.query(DBGenerationVersion)
+            .filter_by(generation_id=generation_id)
+            .order_by(DBGenerationVersion.created_at)
+            .first()
+        )
+    if not v:
+        return None
+    return _version_response(v)
+
+
+def create_version(
+    generation_id: str,
+    label: str,
+    audio_path: str,
+    db: Session,
+    effects_chain: Optional[List[dict]] = None,
+    is_default: bool = False,
+    source_version_id: Optional[str] = None,
+) -> GenerationVersionResponse:
+    """Create a new version for a generation.
+
+    If ``is_default`` is True, all other versions for this generation
+    are un-defaulted first.
+    """
+    if is_default:
+        _clear_defaults(generation_id, db)
+
+    version = DBGenerationVersion(
+        id=str(uuid.uuid4()),
+        generation_id=generation_id,
+        label=label,
+        audio_path=audio_path,
+        effects_chain=json.dumps(effects_chain) if effects_chain else None,
+        source_version_id=source_version_id,
+        is_default=is_default,
+    )
+    db.add(version)
+    db.commit()
+    db.refresh(version)
+
+    # If this version is the default, update the generation's audio_path
+    if is_default:
+        gen = db.query(DBGeneration).filter_by(id=generation_id).first()
+        if gen:
+            gen.audio_path = audio_path
+            db.commit()
+
+    return _version_response(version)
+
+
+def set_default_version(version_id: str, db: Session) -> Optional[GenerationVersionResponse]:
+    """Set a version as the default for its generation."""
+    version = db.query(DBGenerationVersion).filter_by(id=version_id).first()
+    if not version:
+        return None
+
+    _clear_defaults(version.generation_id, db)
+    version.is_default = True
+    db.commit()
+    db.refresh(version)
+
+    # Update generation's audio_path to point to this version
+    gen = db.query(DBGeneration).filter_by(id=version.generation_id).first()
+    if gen:
+        gen.audio_path = version.audio_path
+        db.commit()
+
+    return _version_response(version)
+
+
+def delete_version(version_id: str, db: Session) -> bool:
+    """Delete a version. Cannot delete the last remaining version."""
+    version = db.query(DBGenerationVersion).filter_by(id=version_id).first()
+    if not version:
+        return False
+
+    # Don't allow deleting the last version
+    count = (
+        db.query(DBGenerationVersion)
+        .filter_by(generation_id=version.generation_id)
+        .count()
+    )
+    if count <= 1:
+        return False
+
+    was_default = version.is_default
+    gen_id = version.generation_id
+
+    # Delete audio file
+    audio_path = config.resolve_storage_path(version.audio_path)
+    if audio_path is not None and audio_path.exists():
+        audio_path.unlink()
+
+    db.delete(version)
+    db.commit()
+
+    # If this was the default, promote the first remaining version
+    if was_default:
+        first = (
+            db.query(DBGenerationVersion)
+            .filter_by(generation_id=gen_id)
+            .order_by(DBGenerationVersion.created_at)
+            .first()
+        )
+        if first:
+            first.is_default = True
+            db.commit()
+            gen = db.query(DBGeneration).filter_by(id=gen_id).first()
+            if gen:
+                gen.audio_path = first.audio_path
+                db.commit()
+
+    return True
+
+
+def delete_versions_for_generation(generation_id: str, db: Session) -> int:
+    """Delete all versions for a generation (used when deleting a generation)."""
+    versions = (
+        db.query(DBGenerationVersion)
+        .filter_by(generation_id=generation_id)
+        .all()
+    )
+    count = 0
+    for v in versions:
+        audio_path = config.resolve_storage_path(v.audio_path)
+        if audio_path is not None and audio_path.exists():
+            audio_path.unlink()
+        db.delete(v)
+        count += 1
+    if count > 0:
+        db.commit()
+    return count
+
+
+def _clear_defaults(generation_id: str, db: Session) -> None:
+    """Clear the is_default flag on all versions for a generation."""
+    db.query(DBGenerationVersion).filter_by(
+        generation_id=generation_id, is_default=True
+    ).update({"is_default": False})
+    db.flush()