[NingLin Liu (ninglinLiu)]

Motivation & Context

LocalShellTool(shell=r"C:\Windows\...\powershell.exe") and unquoted AGENT_FRAMEWORK_SHELL paths fail on Windows with FileNotFoundError because resolve_shell used shlex.split, which treats \ as an escape and drops every backslash. The PowerShell -Command flag is also missed after the path is mangled.

Description & Review Guide

• What are the major changes?
  • Add _split_shell_override: on win32, non-POSIX shlex that keeps backslashes and only honours "..." quotes; elsewhere keep shlex.split.
  • Use it for both the shell= argument and AGENT_FRAMEWORK_SHELL.
  • Tests cover unquoted Windows paths, env override, and quoted paths with spaces.
• What is the impact of these changes? Windows shell overrides work; POSIX behaviour unchanged.
• What do you want reviewers to focus on? That win32 splitting matches CommandLineToArgvW-style double-quote handling.

Related Issue

Fixes #9819

AI Assistance

• No material AI assistance was used.
• This is an AI-assisted contribution. I reviewed, understood, and verified all submitted content and accept responsibility for it.

AI assistance details: locating the shlex.split win32 escape behaviour, implementing _split_shell_override, and writing the regression tests and this PR description.

Contribution Checklist

• The code builds clean without any errors or warnings
• All unit tests pass, and I have added new tests where possible
• The PR follows the Contribution Guidelines
• This PR links to an agreed issue with no competing open PR, or the Related Issue section documents a trivial-change or repository-automation exception.
• This is not a breaking change.

[Copilot]

🟡 Changes recommended

Windows shell overrides mishandle partially quoted executable paths and quoted option values, while Windows-mocking tests fail on Linux/macOS because basename handling remains POSIX.

2 open issues

• Preserve quoted Windows paths when parsing shell command overrides · New
• Use Windows path handling when testing PowerShell command construction · New

What changed in this PR

This PR addresses #9819 by preserving Windows backslashes in Python LocalShellTool string overrides while keeping POSIX parsing unchanged.

Changes:

• Adds platform-aware splitting for shell= and AGENT_FRAMEWORK_SHELL.
• Adds regression tests for unquoted Windows paths, environment overrides, and quoted paths containing spaces.

File	Description
python/​packages/​tools/​tests/​test_shell_resolve.py	Adds Windows path and PowerShell flag regression tests.
python/​packages/​tools/​agent_framework_tools/​shell/​_resolve.py	Introduces and applies platform-aware shell override parsing.

_{Review effort: Balanced}

[Eduard van Valkenburg (eavanvalkenburg)]

Escaped quotes still close the quoted segment here. A valid Windows command line can contain \" inside a quoted startup script; treating that quote as a delimiter drops the literal quote and can split one argument into several. Please handle Windows backslash-before-quote rules, including odd/even backslash counts, or use a compatible parser, and add a regression with an escaped quote inside a quoted argument.

[Eduard van Valkenburg (eavanvalkenburg)]

This drops an explicitly quoted empty argument because buf is empty. For example, bash --rcfile "" loses the empty value, so the appended -c is consumed as the rcfile path and the command is misparsed. Please track whether an argument was started separately from buffer content, and cover empty quoted arguments before later options and at the end.