P0+P1 fixes: RCE sandbox, SQL injection, RLS tenant isolation, DB roles, test syntax, attachment, permission registry, membership check

app/services/attachment_service.py

@@ -47,8 +47,18 @@ async def save_attachment(
     filename: str,
     file_content: bytes,
     mime_type: str,
+    is_system_admin: bool = False,
 ) -> dict[str, Any]:
     """Save a file to storage and create an Attachment record."""
+    # Check access on parent entity
+    if not is_system_admin:
+        from app.core.visibility import check_single_entity_access
+        has_access = await check_single_entity_access(
+            db, entity_type, entity_id, user_id, tenant_id, "write", is_system_admin
+        )
+        if not has_access:
+            raise PermissionError(f"No write access to {entity_type} {entity_id}")
+
     # Generate unique filename and relative storage path
     unique_filename = _generate_unique_filename(filename)
     file_path = f"{entity_type}/{entity_id}/{unique_filename}"