Probe the Interpreter the Way the Host Contract Declares It

.husky/pre-commit

@@ -23,15 +23,30 @@ set -e
 # The relative paths below would otherwise resolve against whatever directory the caller was in.
 cd "$(git rev-parse --show-toplevel)"
 
+# The interpreter is chosen by running the probes spec/host-tools.json declares, in its order.
+# On native Windows the python.org install registers `py` and not `python3`.
+# That name resolves to a Microsoft Store alias stub, and Git Bash inherits the Windows PATH.
+# The stub is on PATH and fails when run, so a presence test selects it and the hook then breaks.
+# Running the probe is the whole point: it is what tells a working interpreter from a name.
+if python3 --version >/dev/null 2>&1; then
+    run_py() { python3 "$@"; }
+elif py -3 --version >/dev/null 2>&1; then
+    run_py() { py -3 "$@"; }
+else
+    echo "pre-commit: neither 'python3 --version' nor 'py -3 --version' ran, so the doc gates did not run." >&2
+    echo "pre-commit: see docs/host-setup.md 'What a Host Must Provide'." >&2
+    exit 1
+fi
+
 # The prose gate is scoped to what changed against HEAD, which is the policy for prose.
 # A rule is applied as a file is next edited rather than swept across the tree.
 # Whole-tree costs about 2.2 seconds where the diff-scoped run costs about 0.13.
 # The scope is the working tree rather than the index.
 # A partially staged file is therefore judged on all of its edits, not only the staged ones.
 # CI re-runs the same rules over the whole tree, which is what makes that affordable here.
-python3 scripts/prose_lint.py . --diff HEAD
+run_py scripts/prose_lint.py . --diff HEAD
 
 # The eol check is repo-wide rather than diff-scoped, and it is here because it is already fast.
 # It reads `.gitattributes` against `.editorconfig` for the whole repository and takes no file list.
 # At about 0.04 seconds there is nothing to scope, so scoping it would only make it wrong.
-python3 scripts/repo_gate.py --check eol
+run_py scripts/repo_gate.py --check eol