fix(sdk): fix excessive exception handling in sandbox.write

libs/deepagents/deepagents/backends/sandbox.py

@@ -380,9 +380,6 @@ def write(
     ) -> WriteResult:
         """Create a new file, failing if it already exists.
 
-        Runs a small preflight command to check existence and create parent
-        directories, then transfers content via `upload_files()`.
-
         Args:
             file_path: Absolute path for the new file.
             content: UTF-8 text content to write.
@@ -391,31 +388,23 @@ def write(
             `WriteResult` with `path` on success or `error` on failure.
         """
         # Existence check + mkdir. There is a TOCTOU window between this check
-        # and the upload below — a concurrent process could create the file in
+        # and the upload below - a concurrent process could create the file in
         # between. This is an inherent limitation of splitting the operation;
-        # the risk is minimal in single-agent sandbox environments.
         path_b64 = base64.b64encode(file_path.encode("utf-8")).decode("ascii")
         check_cmd = _WRITE_CHECK_TEMPLATE.format(path_b64=path_b64)
-        try:
-            result = self.execute(check_cmd)
-        except Exception as exc:  # noqa: BLE001  # defense-in-depth for buggy subclass execute()
-            msg = f"Failed to write file '{file_path}': {exc}"
-            return WriteResult(error=msg)
-
+        result = self.execute(check_cmd)
         if result.exit_code != 0 or "Error:" in result.output:
             error_msg = result.output.strip() or f"Failed to write file '{file_path}'"
             return WriteResult(error=error_msg)
 
-        # Transfer content via upload_files()
-        try:
-            responses = self.upload_files([(file_path, content.encode("utf-8"))])
-        except Exception as exc:  # noqa: BLE001  # defense-in-depth for buggy subclass upload_files()
-            msg = f"Failed to write file '{file_path}': {exc}"
-            return WriteResult(error=msg)
+        responses = self.upload_files([(file_path, content.encode("utf-8"))])
         if not responses:
-            return WriteResult(error=f"Failed to write file '{file_path}': upload returned no response")
-        if responses[0].error:
-            return WriteResult(error=f"Failed to write file '{file_path}': {responses[0].error}")
+            # An unreachable condition was reached
+            msg = f"Responses was expected to return 1 result, but it returned {len(responses)} with type {type(responses)}"
+            raise AssertionError(msg)
+        response = responses[0]
+        if response.error:
+            return WriteResult(error=f"Failed to write file '{file_path}': {response.error}")
 
         return WriteResult(path=file_path, files_update=None)
 
@@ -676,6 +665,9 @@ def upload_files(self, files: list[tuple[str, bytes]]) -> list[FileUploadRespons
 
         Implementations must support partial success - catch exceptions per-file
         and return errors in `FileUploadResponse` objects rather than raising.
+
+        Upload files is responsible for ensuring that the parent path exists
+        (if user permissions allow the user to write to the given directory)
         """
 
     @abstractmethod

libs/deepagents/tests/unit_tests/backends/test_sandbox_backend.py

@@ -686,17 +686,6 @@ def test_sandbox_write_returns_correct_result_on_success() -> None:
     assert result.files_update is None
 
 
-def test_sandbox_write_returns_error_on_empty_upload_response() -> None:
-    """Test that write() handles upload_files returning an empty list."""
-    sandbox = MockSandbox()
-    sandbox.upload_files = lambda _files: []  # type: ignore[assignment]
-
-    result = sandbox.write("/test/file.txt", "content")
-
-    assert result.error is not None
-    assert "no response" in result.error
-
-
 def test_sandbox_edit_upload_returns_error_on_empty_upload_response() -> None:
     """Test that upload-path edit handles upload_files returning empty list."""
     sandbox = MockSandbox()