Merge main into directory_explorer: combine text file support with exception tracking

utils/data_explorer.py

@@ -313,9 +313,7 @@ def explore_directories(
 
         # --- Recursive listing ------------------------------------------------
         try:
-            files, total_size = list_objects(
-                s3, S3_BUCKET, prefix, extensions=extensions,
-            )
+            files, total_size = list_objects(s3, S3_BUCKET, prefix, extensions=extensions)
         except botocore.exceptions.ClientError as exc:
             code = exc.response.get("Error", {}).get("Code", "Unknown")
             message = exc.response.get("Error", {}).get("Message", str(exc))
@@ -336,13 +334,14 @@ def explore_directories(
         file_count = len(files)
 
         # --- Permission check on first file -----------------------------------
-        # in "/") for the head_object test.  The listing is already filtered
-        # to the requested extensions, so any non-marker key is a valid probe.
+        # Prefer a real object over a zero-byte directory marker (key ending
+        # in "/") for the head_object test.  The selected key must also match
+        # the extension filter.
         first_key, _ = files[0]
         test_key = first_key
         if first_key.endswith("/") and total_size > 0:
             for key, size in files:
-                if not (key.endswith("/") and size == 0):
+                if not (key.endswith("/") and size == 0) and matches_extensions(key, exts_lower):
                     test_key = key
                     break
 
@@ -436,7 +435,7 @@ def print_results(results: Results, *, extensions: Set[str] | None = None) -> No
         for d in results.available:
             print(f"  {d.prefix}")
             print(
-                f"    {ext_label} files: {d.accessible_count}/{d.total_count} accessible"
+                f"    Matching files ({ext_label}): {d.accessible_count}/{d.total_count} accessible"
                 f" | Total Size: {format_size(d.accessible_size)}"
             )
     else: