Milestone M4 — Rust Shim Integration

Issue: #7 (https://github.com/joelvaneenwyk/py-launch-lab/issues/7)

Description

Build and integrate the pyshim-win Rust crate as a GUI-subsystem executable that can launch Python processes without opening its own console window. The shim resolves interpreters on PATH, detects subsystem types at runtime, and emits structured JSON results.

How it Works

1. pyshim-win is compiled as a Windows GUI-subsystem executable (no console window)
2. It resolves python, pythonw, uv, uvw on the system PATH
3. It spawns child processes using CreateProcess with appropriate flags
4. At runtime it detects whether the target is a console or GUI executable
5. It emits a structured JSON result for each invocation

Tasks

• [ ] Implement pyshim-win CLI with --hide-console flag
• [ ] Implement launch.rs: spawn child process using CreateProcess with appropriate flags
• [ ] Implement resolve.rs: locate python, pythonw, uv, uvw on PATH
• [ ] Implement detect.rs: detect console vs GUI subsystem at runtime
• [ ] Emit structured JSON result from shim
• [ ] Integration test: test_shim.py

Related Issues

• Depends on m1-static-pe-inspection.md - shares PE subsystem classification concepts

Next Steps

• [ ] Cross-compile or build on a Windows runner
• [ ] Verify the shim does not flash a console window when launched
• [ ] Confirm JSON output matches the project schema