Composer Has Stopped Functioning on File Edits (EDIT: .cursorrules file that fixes behavior in comments!)

[wheattoast11]

I haven’t found a solution yet. I’ve gotten the Composer Agent to do some wild things all week (props to the Cursor team for making a real agent that can do many steps and reason through them effectively, provided you’re giving the agent enough info and context to work with).

However even in trying to troubleshoot with Claude, we’re unable to figure out why Composer Agent is trying to apply edits before line 1.

Claude also sees the issue in Agent mode, and is unsure why it is trying to do that. A workaround I found was to let it fail, then go into the file git logs and restore all the edits that SHOULD have been present but they don’t show up.

Example:

1. I’m on a file that composer is trying to edit. This is a brand new session after restarting my PC and restarting cursor several times.

Here’s the prior composers showing the previous failures:

And yet another composer session where this has been failing. So since edit 3, you can see any number of composers fail:

2. Now why do they fail? Let’s take a look:
   
   
   
   
   

So couple possible issues I see. Everything seems to apply BEFORE line 1 in the file, seemingly not keying any lines or cursor position. Is the agent trying to apply edits to a cursor position that doesn’t exist or it can’t find?

Secondly, it shows in the git log so that means its applying somewhere. Funny that this issue occurs as I’m working on a quantum sim project with Claude Restoring from the git log seems to work and save the history.

However even when I do that, I see the Applying or Generating status still pending on the files. In fact on my old composer sessions I still see an Applying action event/indicator right now as I’m typing this.

So there’s either some state mismatch or race conditions on states - perhaps its a function of a really large codebase that I’m working in and Claude not having enough time to finish all steps required in its thinking and tool use/computer use? Not quite sure, but I can say with certainty that Claude was able to work for ~30 minutes on its own accord as Agent yesterday for a single turn, with 100+ steps taken, so hope it’s temporary!

[wheattoast11]

Cursor Operation Rules

Edit Handling

1. Single-Pass Editing

• Make all necessary changes in a single pass

• Group related edits together

• Avoid multiple iterations over the same file

• Use clear edit markers and comments

2. Edit Format

// Format for edit blocks:

````language:path/to/file

// ... existing code ...

{{ edited_code }}

// ... existing code ...

Tool Usage Guidelines

1. File Operations

• Verify file exists before attempting operations

• Check file permissions

• Use absolute paths when possible

• Handle file not found scenarios

2. Search Operations

• Use specific search terms

• Verify search results before acting

• Handle empty search results gracefully

• Cache search results when appropriate

3. Code Analysis

• Verify syntax before making changes

• Check for dependencies

• Validate type safety

• Ensure consistent formatting

Error Prevention

1. Pre-Edit Checks

• Verify file context

• Validate syntax

• Check dependencies

• Confirm file permissions

2. Post-Edit Validation

• Verify syntax after changes

• Check for introduced errors

• Validate type safety

• Ensure formatting consistency

Performance Optimization

1. Operation Batching

• Group related operations

• Minimize file reads/writes

• Cache frequently accessed data

• Use bulk operations when possible

2. Resource Management

• Release resources promptly

• Clean up temporary files

• Manage memory efficiently

• Handle large files appropriately

Best Practices

1. Documentation

• Comment all significant changes

• Explain edit rationale

• Mark skipped sections clearly

• Include context when necessary

2. Error Handling

• Provide clear error messages

• Include recovery steps

• Handle edge cases

• Maintain system stability

3. Version Control

• Respect source control

• Handle conflicts gracefully

• Preserve file history

• Support rollback capability

Operational Constraints

1. File Limits

• Max file size: 10MB

• Max line count: 10,000

• Max edit size: 1,000 lines

• Max search depth: 5 directories

2. Performance Targets

• Edit response: < 100ms

• Search response: < 200ms

• File operations: < 50ms

• Validation: < 150ms