Agent tool `read/problems` on Windows is sensitive to drive letter case. Not stable enough.

[towa-wangmingzhuang]

Problem

On Windows, when Copilot agent uses the read/problems tool, the file path generated by the agent uses a lowercase drive letter (e.g., c:\). As a result, the tool fails to find problems for the file. If I change the drive letter to uppercase (e.g., C:\), the tool works as expected and finds problems.

Expected behavior

The file object should be validated and normalized (e.g., standardize to uppercase drive letter or otherwise) within the tools layer. The agent should not have to care about drive letter case. Ideally, the agent's output would not need to adjust for this platform-specific detail.

Steps to reproduce

1. On Windows, run an agent query that uses read/problems with a path like c:\path\to\file
2. The tool reports "no problems found"
3. Change the path to C:\path\to\file and rerun – now problems are correctly found

Suggestion

• Tools layer should handle drive letter normalization and validation, so that agents are not required to output platform-specific casing.
• Agent should not need to care about drive letter casing when generating tool input.

Additional info

• VS Code version: 1.123.0 (latest up to now)
• OS: Windows 11 Pro
• Copilot/Agent version: latest

Labels: bug, agent-skills, agents, agent-behavior

[towa-wangmingzhuang]

I was using Language Support for Java(TM) by Red Hat Plugin as LSP, working on a Java springboot project with Java 21.

[towa-wangmingzhuang]

On another PC, it only outputs when driver letter is lowercase. It's just sensitive to case but it can vary on different devices.