Clamp view_range end to file length and emit warning instead of error (fixes #154)

openhands_aci/editor/editor.py

@@ -348,30 +348,32 @@ def view(self, path: Path, view_range: list[int] | None = None) -> CLIResult:
                 f'Its first element `{start_line}` should be within the range of lines of the file: {[1, num_lines]}.',
             )
 
-        if end_line > num_lines:
-            raise EditorToolParameterInvalidError(
-                'view_range',
-                view_range,
-                f'Its second element `{end_line}` should be smaller than the number of lines in the file: `{num_lines}`.',
-            )
+        # Normalize end_line and provide a warning if it exceeds file length
+        warning_message: str | None = None
+        if end_line == -1:
+            end_line = num_lines
+        elif end_line > num_lines:
+            warning_message = f"We only show up to {num_lines} since there's only {num_lines} lines in this file"
+            end_line = num_lines
 
-        if end_line != -1 and end_line < start_line:
+        if end_line < start_line:
             raise EditorToolParameterInvalidError(
                 'view_range',
                 view_range,
                 f'Its second element `{end_line}` should be greater than or equal to the first element `{start_line}`.',
             )
 
-        if end_line == -1:
-            end_line = num_lines
-
         file_content = self.read_file(path, start_line=start_line, end_line=end_line)
 
         # Get the detected encoding
         output = self._make_output(
             '\n'.join(file_content.splitlines()), str(path), start_line
         )  # Remove extra newlines
 
+        # Prepend warning if we truncated the end_line
+        if warning_message:
+            output = f'NOTE: {warning_message}\n\n{output}'
+
         return CLIResult(
             path=str(path),
             output=output,

tests/integration/editor/test_error_handling.py

@@ -86,18 +86,15 @@ def test_view_range_validation(temp_file):
         'should be a list of two integers' in result_json['formatted_output_and_error']
     )
 
-    # Test out of bounds range
+    # Test out of bounds range: should clamp to file end and show a warning
     result = file_editor(
         command='view',
         path=temp_file,
         view_range=[1, 10],  # File only has 3 lines
         enable_linting=False,
     )
     result_json = parse_result(result)
-    assert (
-        'should be smaller than the number of lines'
-        in result_json['formatted_output_and_error']
-    )
+    assert 'NOTE: We only show up to 3 since there\'s only 3 lines in this file' in result_json['formatted_output_and_error']
 
     # Test invalid range order
     result = file_editor(