[Bug] Windows: LSP server receives malformed file URIs (file://C:\... instead of file:///C:/...)

Summary

On Windows, Claude Code sends incorrect file:// URIs to LSP servers.
The generated URIs use the format file://C:\path\to\file instead of
the correct RFC 8089 format file:///C:/path/to/file.

Environment

• OS: Windows 10 Pro
• Claude Code: latest
• LSP Server: Eclipse JDT Language Server (jdtls)

Steps to Reproduce

1. Install a LSP plugin (e.g. jdtls-lsp) on Windows
2. Open a Java project
3. Attempt any LSP operation (documentSymbol, hover, etc.)

Expected Behavior

URIs sent to LSP servers should follow RFC 8089:

file:///C:/Users/username/project/src/Main.java

Actual Behavior

URIs are malformed:

file://C:\Users\username\project\src\Main.java

This causes LSP servers to fail with:

java.net.URISyntaxException: Illegal character in authority at index 9:
file://C:\Users\...

The issue affects all LSP operations including:

• initialize request (rootUri, workspaceFolders[].uri)
• textDocument/didOpen
• textDocument/documentSymbol
• textDocument/hover
• textDocument/definition

Workaround

A Python proxy that intercepts all LSP messages and patches the URIs
before forwarding to the actual LSP server.

def fix_uri(uri):
    if isinstance(uri, str) and uri.startswith('file://') and not uri.startswith('file:///'):
        return 'file:///' + uri[7:].replace('\', '/')
    return uri

Notes

This appears to be a Windows-specific issue where backslash path separators
and the missing third slash cause RFC 8089 non-compliant URIs to be generated.