User skill not used

[meganrogge]

Testing #280352

I have a user skill at

I see this is a known skill in the chat debug logs.

However, I noticed that the agent doesn't use it. I tried tweaking the description and explicitly saying use the debugging skill. I don't have this issue with the workspace defined skill.

---
name: debugging-and-bug-fixing
description: Debugging specialist for errors, test failures, and unexpected behavior. Use when encountering bugs, errors, or unexpected behavior that needs investigation and fixing.
---

# Debugging and Bug Fixing

## Instructions

You are an expert debugger specializing in root cause analysis and bug resolution.

When invoked:
1. **Capture the problem**: Collect error messages, stack traces, and reproduction steps
2. **Identify the failure location**: Locate where the bug occurs in the codebase
3. **Analyze root cause**: Investigate why the bug is happening, not just symptoms
4. **Implement minimal fix**: Apply the smallest change that resolves the issue
5. **Verify the solution**: Test that the fix works and doesn't introduce new problems

## Debugging Process

- Analyze error messages and logs carefully
- Check recent code changes that might have introduced the bug
- Form hypotheses about the cause and test them systematically
- Add strategic debug logging to understand program state
- Inspect variable states and execution flow
- Review related code for similar issues

## For Each Bug, Provide

- **Root cause explanation**: Clear description of why the bug occurred
- **Evidence**: Supporting information that confirms the diagnosis
- **Specific code fix**: Exact changes needed to resolve the issue
- **Testing approach**: How to verify the fix works
- **Prevention recommendations**: How to avoid similar bugs in the future

## Best Practices

- Focus on fixing the underlying issue, not just symptoms
- Keep fixes minimal and targeted
- Document your reasoning and findings
- Consider edge cases and potential side effects
- Run existing tests to ensure no regressions
- Add new tests to prevent the bug from recurring

## Examples

### Example 1: Null Pointer Error

Error: Cannot read property 'name' of undefined
Location: user-profile.js:42

Root Cause: User object not validated before accessing properties
Fix: Add null check before property access
Prevention: Implement input validation at API boundaries

### Example 2: Off-by-One Error

Error: Array index out of bounds
Location: data-processor.js:156

Root Cause: Loop condition uses <= instead of <
Fix: Change loop condition from i <= array.length to i < array.length
Prevention: Use array methods like forEach() to avoid manual indexing

[meganrogge]

[ming86]

I encountered the same issue.

The skill is included in the system prompt's <skills> section; however, when I tell copilot to read the skill, the read_file tool refused to read skill files stored under ~/.claude/skills/.

Environment:

• Copilot Chat: 0.34.2025120301
• VS Code: 1.107.0-insider
• macOS 15.7.2

Error (copied from the tool call log):

Tool Call - toolu_01MHbAQ84pKEEyaFDpHZqCnS__vscode-1764767257404
Request
id   : toolu_01MHbAQ84pKEEyaFDpHZqCnS__vscode-1764767257404
tool : read_file
args : {
  "filePath": "/Users/username/.claude/skills/agent-instructions/SKILL.md"
}

Response
ERROR while calling tool: File /Users/username/.claude/skills/agent-instructions/SKILL.md is outside of the workspace, and not open in an editor, and can't be read
Please check your input and try again.

Notes:

• The failure appears to be because the file is outside the current workspace and not open in the editor.
• I can reproduce this when the skill path is under my home directory (~/.claude/skills/) even though the skill is referenced in .

[Decem-Y]

Me too

[meganrogge]

@aeschli should this have the bug label?

[aeschli]

To verify:

• set "chat.useClaudeSkills": true
• create a skill at ~/.claude/skills/vscode-folding-strategies/SKILL.md

---
name: vscode-folding-strategies
description: Describes what strategies VS Code uses when folding text in the editor
---

The default folding strategy is based purely on the indentation of lines. A folding region starts when a line has a smaller indent than one or more following lines, and ends when there is a line with the same or smaller indent.

Language extensions can provide language agnostic folding providers that use the parser included in the extension.

• ask: How does folding work in VS Code

[meganrogge]

@aeschli it's still not finding my debugging skill

[meganrogge]

Has the setting changed? No skills are included in the agent prompt now.