Data corruption fix

Author: youngcoder45

bot.py

@@ -1,5 +1,6 @@
 import asyncio
 import logging
+from logging.handlers import RotatingFileHandler
 import os
 from typing import Optional
 
@@ -13,14 +14,31 @@
 load_dotenv()
 
 # Configure logging
+handlers: list[logging.Handler] = [logging.StreamHandler()]
+
+# File logging is best-effort: some hosts have very limited disk.
+try:
+    handlers.append(
+        RotatingFileHandler(
+            'modmail_bot.log',
+            maxBytes=1_000_000,
+            backupCount=2,
+            encoding='utf-8',
+            delay=True,
+        )
+    )
+except OSError:
+    # Disk full / read-only FS / permission issue — continue with console logging.
+    pass
+
 logging.basicConfig(
     level=getattr(logging, os.getenv('LOG_LEVEL', 'INFO')),
     format='%(asctime)s - %(name)s - %(levelname)s - %(message)s',
-    handlers=[
-        logging.FileHandler('modmail_bot.log'),
-        logging.StreamHandler()
-    ]
+    handlers=handlers,
 )
+
+# Prevent noisy "--- Logging error ---" tracebacks in production.
+logging.raiseExceptions = False
 logger = logging.getLogger(__name__)
 
 class ModMailBot(commands.Bot):

cogs/modmail.py

@@ -93,7 +93,13 @@ async def _load_sessions_from_file(self):
         try:
             async with aiofiles.open(self.SESSIONS_FILE, "r", encoding="utf-8") as fh:
                 content = await fh.read()
-                data = json.loads(content)
+                if not content.strip():
+                    return
+                try:
+                    data = json.loads(content)
+                except json.JSONDecodeError:
+                    logger.warning("modmail: sessions file is not valid JSON; ignoring")
+                    return
             for k, v in data.items():
                 try:
                     self.modmail_sessions[int(k)] = v
@@ -106,8 +112,10 @@ async def _persist_sessions_to_file(self):
         try:
             self.SESSIONS_FILE.parent.mkdir(parents=True, exist_ok=True)
             dumpable = {str(k): v for k, v in self.modmail_sessions.items()}
-            async with aiofiles.open(self.SESSIONS_FILE, "w", encoding="utf-8") as fh:
+            tmp_path = self.SESSIONS_FILE.with_suffix(self.SESSIONS_FILE.suffix + ".tmp")
+            async with aiofiles.open(tmp_path, "w", encoding="utf-8") as fh:
                 await fh.write(json.dumps(dumpable))
+            tmp_path.replace(self.SESSIONS_FILE)
         except Exception:
             logger.exception("modmail: failed to persist sessions to file")