fix(claude-code-mcp): resolve venv interpreter in the Windows Scripts/ layout (#1758, 3a)

[eldar702]

Problem

hindsight-integrations/claude-code/scripts/run_mcp.sh resolves the plugin venv interpreter via resolve_py(), which only probes ${VENV}/bin/python and ${VENV}/bin/python.exe. A standard Windows CPython venv — produced by the python.org installer, the Windows Store Python, and py -m venv — puts the interpreter at ${VENV}/Scripts/python.exe, never under bin/.

So on the common Windows setup resolve_py returns an empty $PY, the launcher falls through to venv re-creation, and re-creation then fails whenever python/python3 aren't on the spawning process's PATH (frequent when Claude Code's VS Code extension host spawns the server) → "MCP server never starts, no useful error".

This is sub-item 3a of #1758. The prior fix (#1564/#1565) only added the msys2/mingw bin/python.exe layout; this composes cleanly with it.

Fix (scripts/run_mcp.sh)

• Add one elif branch to resolve_py() for the ${VENV}/Scripts/python.exe layout (with the matching Scripts/pip.exe).
• Update the now-misleading venv create failed: no python interpreter at ${VENV}/bin/ message to also mention ${VENV}/Scripts/.

POSIX behaviour is unchanged — the new branch only matches Windows-layout venvs, and the existing bin/ branches still take precedence.

Test (RED-first)

New tests/test_run_mcp.py invokes the real bash resolve_py function (extracted from the script so none of its top-level side effects run) against a fabricated venv tree:

• test_windows_scripts_layout_is_resolved — venv has Scripts/python.exe and no bin/. RED on main (resolve_py returns empty $PY), GREEN after the elif.
• test_posix_bin_layout_is_resolved — regression guard asserting the POSIX bin/python path still wins.

Verification

$ python -m pytest tests/test_run_mcp.py -v   # pre-fix
test_windows_scripts_layout_is_resolved FAILED   # got: '' (the bug)
test_posix_bin_layout_is_resolved        PASSED

$ python -m pytest tests/                      # post-fix
183 passed in 0.61s
$ bash -n scripts/run_mcp.sh                    # syntax OK

Scope: 2 files, +105/-1, no new dependencies, scoped to 3a only.

🤖 AI-assistance: drafted with Claude (Opus 4.8), reviewed for correctness