Succesful data exploration

Code/python/src/adsbpy/fetch.py

@@ -122,24 +122,27 @@ async def extract_adsb_data(cmd: List[str]) -> None:
 def extract_tar_sync(tar_paths: List[Path], extract_dir: Path) -> Path:
     """Synchronous tar extraction (CPU-bound, run in thread pool)."""
     extract_dir.mkdir(parents=True, exist_ok=True)
-    
+
     if len(tar_paths) == 1:
         tar_path = tar_paths[0]
     else:
-        # Concatenate multi-part tar files
-        tar_paths = [p for p in tar_paths if len(p.suffix) == 3]
-        tar_path = extract_dir / tar_paths[0].stem
-        
-        logger.info(f"Concatenating {len(tar_paths)} parts → {pretty_path(tar_path)}")
-        with open(tar_path, 'wb') as outfile:
-            for part in tar_paths:
-                with open(part, 'rb') as infile:
+        # Keep only multipart fragments like .aa, .ab, .ac ...
+        parts = [p for p in tar_paths if len(p.suffix) == 3]
+
+        # Derive correct base archive name: strip only the multipart suffix
+        base = parts[0].with_suffix("")  # "foo.tar.aa" → "foo.tar"
+        tar_path = extract_dir / base.name
+
+        logger.info(f"Concatenating {len(parts)} parts → {pretty_path(tar_path)}")
+        with open(tar_path, "wb") as outfile:
+            for part in sorted(parts):
+                with open(part, "rb") as infile:
                     shutil.copyfileobj(infile, outfile)
 
     logger.info(f"Extracting {pretty_path(tar_path)} → {pretty_path(extract_dir)}")
     with tarfile.open(tar_path) as tf:
         tf.extractall(path=extract_dir)
-    
+
     return extract_dir