append_to_file

The append_to_file tool adds content to the end of a specified file. If the file doesn't exist, it creates the file with the provided content. It automatically handles directory creation if needed.

Parameters

The tool accepts these parameters:

• path (required): The relative path (from the workspace root) of the file to append to.
• content (required): The content to append to the file.

What It Does

This tool appends the provided content to the end of the file specified by path. If the target file doesn't exist, the tool creates it and populates it with the content. It also ensures any necessary parent directories for the file path are created. Changes are presented in a diff view for user approval before being saved.

When is it used?

• When adding new entries to log files.
• When appending data records to existing datasets (e.g., CSV, JSON lines).
• When incrementally building a file where new content should always go at the end.
• When creating a file for the first time with initial content, especially if subsequent operations will append to it.

Key Features

• Append or Create: Appends content to existing files or creates new files if they don't exist.
• Interactive Approval: Shows proposed changes (append or new file creation) in a diff view, requiring explicit user approval.
• User Edit Support: Allows editing the proposed content directly within the diff view before final approval.
• Automatic Directory Creation: Automatically creates parent directories if they don't exist for the specified path.
• Content Preprocessing: Cleans content by removing potential AI model artifacts (like code fences) and unescaping HTML entities.
• Access Control: Validates file access against .rooignore rules.
• Diff View Integration: Opens the file in a diff view, scrolling to the first change for review.
• Partial Update Support: Can handle streaming content (block.partial) into the diff view.
• Context Tracking: Records the file edit operation for context management.

Limitations

• Append Only: Content is always added to the end of the file; it cannot insert content at other positions.
• Review Overhead: The mandatory diff view approval adds an interactive step.
• Potential for Large Files: While generally efficient, appending large amounts of content repeatedly might impact performance less than write_to_file but more than apply_diff for targeted changes.

How It Works

When the append_to_file tool is invoked, it follows this process:

1. Parameter Validation: Checks for required path and content. Reports errors if missing.
2. Path Processing: Resolves the relative path to an absolute path and checks if it's outside the workspace.
3. Access Control: Validates file access against .rooignore rules using rooIgnoreController.
4. File Existence Check: Determines if the file exists using fileExistsAtPath.
5. Content Preprocessing: Removes markdown code fences, unescapes HTML entities (for non-Claude models), and strips potential line numbers.
6. Diff View Interaction:
   • Opens the file in the diff view (cline.diffViewProvider.open).
   • If the file exists, prepares the newContent by prefixing it with the originalContent and a newline (\n).
   • Updates the diff view with the final content (cline.diffViewProvider.update), supporting partial (streaming) updates.
   • Scrolls to the first detected change after a complete update (cline.diffViewProvider.scrollToFirstDiff).
7. User Approval: Presents the change (append or creation) via askApproval. Shows a formatted diff if appending. Reverts if rejected.
8. Saving Changes: If approved, saves the changes using cline.diffViewProvider.saveChanges.
9. File Context Tracking: Tracks the edit using cline.getFileContextTracker().trackFileContext.
10. Handling User Edits: If the user edited the content in the diff view, reports the final merged content back to the AI.
11. Error Handling: Uses the handleError callback for issues. Resets the diff view on completion, error, or rejection.
12. Result Reporting: Reports success (including user edits) or failure back to the AI model using pushToolResult.

Usage Examples

Appending log entries to an existing file:

<append_to_file>
<path>logs/application.log</path>
<content>
[2024-04-18 10:30:00] INFO: User logged in successfully.
[2024-04-18 10:30:05] WARN: Disk space running low.
</content>
</append_to_file>

Creating a new file and adding initial content (if notes.md doesn't exist):

<append_to_file>
<path>project/docs/notes.md</path>
<content>
# Project Notes

- Initial setup complete.
- Need to configure database connection.
</content>
</append_to_file>