refactor: Re-export Crawlee FileSystemStorageClient and clarify Apify FS docstring

Author: vdusek

src/apify/storage_clients/__init__.py

@@ -1,7 +1,9 @@
-# `MemoryStorageClient` is re-exported from Crawlee unchanged. Unlike `ApifyFileSystemStorageClient`, it does
-# not preserve the Actor `INPUT` record on purge, and unlike the Apify dataset clients it does not charge for
-# the `PAY_PER_EVENT` pricing model, so prefer the Apify clients when either behavior matters.
-from crawlee.storage_clients import MemoryStorageClient, StorageClient
+# `FileSystemStorageClient`, `MemoryStorageClient`, and `StorageClient` are re-exported unchanged from Crawlee.
+# The file-system client also has an Apify variant, `ApifyFileSystemStorageClient` (the default local client),
+# which preserves the Actor `INPUT` record on purge and charges for the `PAY_PER_EVENT` pricing model. There is
+# no Apify variant of `MemoryStorageClient`, so it is re-exported as-is and provides neither behavior. Prefer
+# the Apify clients when either behavior matters.
+from crawlee.storage_clients import FileSystemStorageClient, MemoryStorageClient, StorageClient
 
 from ._apify import ApifyStorageClient
 from ._file_system import ApifyFileSystemStorageClient
@@ -10,6 +12,7 @@
 __all__ = [
     'ApifyFileSystemStorageClient',
     'ApifyStorageClient',
+    'FileSystemStorageClient',
     'MemoryStorageClient',
     'SmartApifyStorageClient',
     'StorageClient',

src/apify/storage_clients/_file_system/_storage_client.py

@@ -19,11 +19,16 @@
 
 @docs_group('Storage clients')
 class ApifyFileSystemStorageClient(FileSystemStorageClient):
-    """Apify-specific implementation of the file system storage client.
+    """Apify SDK variant of Crawlee's `FileSystemStorageClient`, used as the default local storage client.
 
-    The only difference is that it uses `ApifyFileSystemKeyValueStoreClient` for key-value stores,
-    which overrides the `purge` method to delete all files in the key-value store directory
-    except for the metadata file and the `INPUT.json` file.
+    It extends the Crawlee file-system client with Apify-specific behavior that keeps local runs consistent
+    with the Apify platform:
+
+    - Key-value stores use `ApifyFileSystemKeyValueStoreClient`, which preserves the Actor input file (e.g.
+      `INPUT.json`) and the metadata file when purging, and maps the logical `INPUT` key to the input file on
+      disk.
+    - Datasets use `ApifyFileSystemDatasetClient`, which charges for the `PAY_PER_EVENT` pricing model so it
+      can be exercised locally.
     """
 
     @override