feat: add logging config

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

src/logging_config.py

@@ -0,0 +1,54 @@
+"""Logging configuration for ai-chat-exporter."""
+
+import logging
+import logging.handlers
+import os
+from pathlib import Path
+
+
+def setup_logging(
+    level: int = logging.INFO,
+    log_file: str | None = None,
+    no_log_file: bool = False,
+) -> None:
+    """Configure console and rotating file logging.
+
+    Args:
+        level: Console log level (e.g. logging.DEBUG, logging.INFO).
+        log_file: Path to the log file. None uses the default location.
+                  Set to "none" (string) to disable file logging.
+        no_log_file: If True, disables file logging entirely.
+    """
+    fmt = "%(asctime)s | %(levelname)-8s | %(name)s | %(message)s"
+    datefmt = "%Y-%m-%d %H:%M:%S"
+    formatter = logging.Formatter(fmt, datefmt=datefmt)
+
+    root = logging.getLogger()
+    root.setLevel(logging.DEBUG)  # root catches everything; handlers filter
+
+    # Remove any existing handlers (idempotent for test environments)
+    root.handlers.clear()
+
+    # Console handler
+    console = logging.StreamHandler()
+    console.setLevel(level)
+    console.setFormatter(formatter)
+    root.addHandler(console)
+
+    # File handler
+    if not no_log_file and log_file and log_file.lower() != "none":
+        log_path = Path(log_file).expanduser()
+        log_path.parent.mkdir(parents=True, exist_ok=True)
+        file_handler = logging.handlers.RotatingFileHandler(
+            log_path,
+            maxBytes=5 * 1024 * 1024,  # 5 MB
+            backupCount=3,
+            encoding="utf-8",
+        )
+        file_handler.setLevel(logging.DEBUG)  # always DEBUG to file
+        file_handler.setFormatter(formatter)
+        root.addHandler(file_handler)
+
+    # Suppress noisy third-party loggers
+    logging.getLogger("urllib3").setLevel(logging.WARNING)
+    logging.getLogger("requests").setLevel(logging.WARNING)