Missing leading semicolon when appending to PATH on Windows

[GGLinnk-ReadOnly]

Type: Bug

Context:

• VS Code version: 1.106.3 (user setup)
• Extension version: 2025.16.0
• OS: Windows 11 Enterprise 24H2 (26100.7171)
• Shell: PowerShell 7.5.4
• UV .venv (uv 0.9.9 (4fac4cb7e 2025-11-12))

Behaviour:

When the debugpy extension appends its path to the PATH environment variable, it does not check if the existing PATH ends with a semicolon. If another tool (e.g., Bun) writes a PATH entry without a trailing semicolon, the paths get concatenated:

C:\Users\ggrondin.ext\.bun\binc:\Users\ggrondin.ext\.vscode\extensions\ms-python.debugpy-2025.16.0-win32-x64\bundled\scripts\noConfigScripts

Expected:

The extension should either:

• Prepend a semicolon before adding its path, or
• Check if the existing PATH ends with a semicolon and add one if missing

Steps to reproduce:

1. Have a PATH entry that does not end with a semicolon (e.g., current version of bun).
2. Open a Python project with a venv in VSCode (e.g, current version of uv (uv 0.9.9 (4fac4cb7e 2025-11-12))).
3. Open an integrated terminal.
4. Check $env:PATH — the paths are concatenated without separator.

Note:

This might be related to (but probably different from) #740 which fixed double semicolons (;;). This issue is about the missing leading semicolon when appending (most probably).

Related: oven-sh/bun#16811

[readncode]

I ran into this issue and it took me a long time to track down.
Version 2025.16.0
vscode 1.107.0-insider