fix

src/app/cli.py

@@ -11,6 +11,7 @@ from .core.sync.executor import ActionExecutor
 from .core.events.event_bus import EventBus
 import re
 from .core.utils.yt import extract_playlist_id
+from .core.utils.deps import DependencyError
 
 
 def main(argv: list[str] | None = None) -> int:

src/app/core/utils/deps.py

@@ -0,0 +1,101 @@
+from __future__ import annotations
+
+import os
+import subprocess
+import sys
+from dataclasses import dataclass
+from pathlib import Path
+from shutil import which
+from typing import Optional, Tuple
+
+
+class DependencyError(RuntimeError):
+    pass
+
+
+@dataclass(frozen=True)
+class DependencyStatus:
+    yt_dlp_ok: bool
+    yt_dlp_version: Optional[str]
+    ffmpeg_ok: bool
+    ffmpeg_path: Optional[str]
+    ffprobe_ok: bool
+    ffprobe_path: Optional[str]
+
+
+def get_yt_dlp_version() -> Optional[str]:
+    try:
+        import yt_dlp  # type: ignore
+
+        # yt-dlp exposes version in different places depending on install
+        return getattr(yt_dlp, "__version__", None) or getattr(getattr(yt_dlp, "version", None), "__version__", None)
+    except Exception:
+        return None
+
+
+def ensure_yt_dlp_available() -> str:
+    """
+    Ensures yt-dlp Python package is importable. Returns version string when known.
+    """
+    try:
+        import yt_dlp  # noqa: F401  # type: ignore
+    except Exception as exc:
+        raise DependencyError("yt-dlp Python package is required. Install with: pip install -U yt-dlp") from exc
+    return get_yt_dlp_version() or "unknown"
+
+
+def _resolve_tool_paths(tool_hint: Optional[str], exe_name: str) -> Tuple[Optional[str], Optional[str]]:
+    """
+    Returns (resolved_exe_path, resolved_dir_hint).
+    - If tool_hint is a file path, use it.
+    - If tool_hint is a directory, append exe_name.
+    - Otherwise, treat tool_hint as a command and fall back to PATH resolution.
+    """
+    if tool_hint:
+        hint = Path(tool_hint)
+        # Expand envvars (%FFMPEG%) etc.
+        expanded = Path(os.path.expandvars(str(hint)))
+        if expanded.is_dir():
+            cand = expanded / exe_name
+            if cand.exists():
+                return str(cand), str(expanded)
+        if expanded.exists():
+            return str(expanded), str(expanded.parent)
+
+    # PATH lookup
+    found = which(exe_name)
+    if found:
+        return found, str(Path(found).parent)
+    return None, None
+
+
+def ensure_ffmpeg_available(ffmpeg_hint: Optional[str]) -> Tuple[str, str]:
+    """
+    Ensures both ffmpeg and ffprobe are runnable. Returns (ffmpeg_path, ffprobe_path).
+    """
+    ffmpeg_exe = "ffmpeg.exe" if sys.platform.startswith("win") else "ffmpeg"
+    ffprobe_exe = "ffprobe.exe" if sys.platform.startswith("win") else "ffprobe"
+
+    ffmpeg_path, ffmpeg_dir = _resolve_tool_paths(ffmpeg_hint, ffmpeg_exe)
+    if not ffmpeg_path:
+        raise DependencyError("ffmpeg not found. Install ffmpeg or set 'ffmpeg_path' in config.")
+
+    # For ffprobe prefer the same directory if we have one
+    ffprobe_path = None
+    if ffmpeg_dir:
+        cand = Path(ffmpeg_dir) / ffprobe_exe
+        if cand.exists():
+            ffprobe_path = str(cand)
+    if not ffprobe_path:
+        ffprobe_path, _ = _resolve_tool_paths(None, ffprobe_exe)
+    if not ffprobe_path:
+        raise DependencyError("ffprobe not found (usually ships with ffmpeg). Install ffmpeg or fix 'ffmpeg_path'.")
+
+    # Smoke test (fast)
+    try:
+        subprocess.run([ffmpeg_path, "-version"], check=True, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
+        subprocess.run([ffprobe_path, "-version"], check=True, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
+    except Exception as exc:
+        raise DependencyError("ffmpeg/ffprobe exist but are not runnable. Check permissions/architecture/path.") from exc
+
+    return ffmpeg_path, ffprobe_path

src/app/main.py

@@ -14,6 +14,7 @@ from .core.sync.service import SyncService
 from .core.sync.executor import ActionExecutor
 from .core.models import SyncActionType
 from .core.utils.yt import extract_playlist_id
+from .core.utils.deps import DependencyError
 
 
 def bootstrap(db_path: Path | None = None) -> None: