feat: add persistent logging to console + rotating file

plans/project plan.md

@@ -2,7 +2,7 @@
 
 ## Subject Area
 
-- Tool for downloading and synchronizing YouTube playlists.
+- Tool for downloading and synchronizing local YouTube playlists.
 - Focuses on batch downloading, format selection (audio and/or video), configurable quality and keeping local copies synced with playlist changes.
 - Targets power users and archivists who need large-scale, repeatable playlist archiving and ongoing synchronization, with GUI interface.
 
@@ -14,7 +14,7 @@
 
 ## Users Definition
 
-Individuals who need to download a large number of videos or audio files from a YouTube playlist and keep it updated
+Individuals who need to have a local youtube playlist synced with a large number of videos or audio files
 
 ## Functionality Definition
 
@@ -38,13 +38,10 @@ Individuals who need to download a large number of videos or audio files from a
 ## Platforms
 
 - Desktop: Windows (Primary), Linux
-- Docker
-- Possible Future: Web App, Android App (via shared FastAPI backend)
 
 ## Architecture & Languages
 
-- Core Engine: Python (yt-dlp wrapper)
+- Core Engine: Python (yt-dlp)
-- Backend API: FastAPI (Local localhost-only boundary)
 - Desktop Frontend: PySide6 (Qt for Python)
 - Distribution: PyInstaller / Briefcase (Windows .exe, Linux AppImage)
   

src/app/cli.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import argparse
 import asyncio
+import logging
 from pathlib import Path
 
 from .config.settings import Settings
@@ -12,6 +13,7 @@ from .core.events.event_bus import EventBus
 import re
 from .core.utils.yt import extract_playlist_id
 from .core.utils.deps import DependencyError
+from .core.utils.logging_setup import configure_logging
 
 
 def main(argv: list[str] | None = None) -> int:
@@ -20,8 +22,12 @@ def main(argv: list[str] | None = None) -> int:
     parser.add_argument("--db", type=Path, default=Path("app/data/app.db"), help="Path to SQLite database")
     parser.add_argument("--playlist", type=int, default=None, help="Only run for a specific playlist index (0-based)")
     parser.add_argument("--verbose", action="store_true", help="Print detailed events (rename/recycle/start)")
+    parser.add_argument("--debug", action="store_true", help="Enable debug logging to console + app/data/app.log")
     args = parser.parse_args(argv)
 
+    configure_logging(verbose=bool(args.debug), log_file=Path("app/data/app.log"))
+    log = logging.getLogger(__name__)
+
     settings = Settings()
     db = Database(args.db.resolve())
     service = SyncService(db)
@@ -88,14 +94,17 @@ def main(argv: list[str] | None = None) -> int:
             counts[a.type.name] = counts.get(a.type.name, 0) + 1
         summary = ", ".join(f"{k}:{v}" for k, v in sorted(counts.items()))
         print(f"Playlist {pid}: {len(actions)} actions → {summary}")
+        log.info("playlist=%s actions=%s summary=%s", pid, len(actions), summary)
         if args.apply and actions:
             try:
                 asyncio.run(executor.execute(actions, pl))
             except DependencyError as e:
                 print(f"ERROR: {e}")
+                log.error("dependency error: %s", e)
                 return 2
             db.set_playlist_last_sync(pid)
             print(f"Applied actions for {pid}.")
+            log.info("playlist=%s applied_actions=%s", pid, len(actions))
 
     return 0
 

src/app/core/download/workers.py

@@ -1,11 +1,13 @@
 from __future__ import annotations
 
 import asyncio
+import logging
 from .downloader import Downloader
 from .queue_manager import DownloadJob, JobState
 
 
 async def default_worker(job: DownloadJob, *, max_retries: int = 2, delay_seconds: float = 1.5):
+    log = logging.getLogger(__name__)
     dl = Downloader(ffmpeg_path=job.ffmpeg_path)
     attempt = 0
     while attempt <= max_retries:
@@ -14,4 +16,13 @@ async def default_worker(job: DownloadJob, *, max_retries: int = 2, delay_second
             return
         attempt += 1
         if attempt <= max_retries:
-            await asyncio.sleep(delay_seconds)
+            wait = delay_seconds * (2 ** (attempt - 1))
+            log.warning(
+                "retrying download attempt=%s/%s video_id=%s wait=%.1fs error=%s",
+                attempt,
+                max_retries,
+                getattr(getattr(job, "item", None), "video_id", None),
+                wait,
+                job.error,
+            )
+            await asyncio.sleep(wait)

src/app/core/utils/logging_setup.py

@@ -0,0 +1,37 @@
+from __future__ import annotations
+
+import logging
+from logging.handlers import RotatingFileHandler
+from pathlib import Path
+
+
+def configure_logging(*, verbose: bool = False, log_file: Path | None = None) -> None:
+    """
+    Configure app-wide logging.
+
+    - Console handler always enabled.
+    - Rotating file handler enabled when log_file is provided.
+    """
+    root = logging.getLogger()
+    root.setLevel(logging.DEBUG if verbose else logging.INFO)
+
+    # Avoid duplicate handlers on repeated calls (tests, re-entrypoints).
+    if getattr(configure_logging, "_configured", False):
+        return
+
+    fmt = logging.Formatter("%(asctime)s %(levelname)s %(name)s: %(message)s")
+
+    console = logging.StreamHandler()
+    console.setLevel(logging.DEBUG if verbose else logging.INFO)
+    console.setFormatter(fmt)
+    root.addHandler(console)
+
+    if log_file is not None:
+        log_file.parent.mkdir(parents=True, exist_ok=True)
+        file_handler = RotatingFileHandler(str(log_file), maxBytes=2_000_000, backupCount=3, encoding="utf-8")
+        file_handler.setLevel(logging.DEBUG)
+        file_handler.setFormatter(fmt)
+        root.addHandler(file_handler)
+
+    configure_logging._configured = True  # type: ignore[attr-defined]
+