feat: implement Layer 2 per-file transit, RAM session, mock buffer, and tests (v0.2.0)

upload/backend/session/__init__.py

@@ -0,0 +1,38 @@
+"""In-memory хранилище сессий с TTL и лимитами.
+
+Каждая операция — в отдельном файле, общее состояние — в state.py.
+Импорт как единый пакет:
+
+    from upload.backend.session import create_session, add_file, get_files
+"""
+
+from .create_session import create_session
+from .add_file import add_file
+from .get_files import get_files, file_count
+from .store_result import store_result, get_result
+from .store_csv import store_csv, get_csv
+from .ttl import touch, pause_ttl, resume_ttl
+from .cancel import request_cancel, get_cancel_event
+from .cleanup import cleanup
+from .state import TTL_SECONDS, MAX_FILE_BYTES, MAX_SESSION_BYTES, configure
+
+__all__ = [
+    "create_session",
+    "add_file",
+    "get_files",
+    "file_count",
+    "store_result",
+    "get_result",
+    "store_csv",
+    "get_csv",
+    "touch",
+    "pause_ttl",
+    "resume_ttl",
+    "request_cancel",
+    "get_cancel_event",
+    "cleanup",
+    "configure",
+    "TTL_SECONDS",
+    "MAX_FILE_BYTES",
+    "MAX_SESSION_BYTES",
+]