fix(claude): reject unsupported Python launcher candidates

loopx/claude_goal_mode/scripts/install.py

@@ -138,7 +138,7 @@ def _shell_command(value: str, *, powershell: bool) -> str:
 
 
 def _launches_python(py: str) -> bool:
-    """True when running `py` actually starts an interpreter.
+    """True when running `py` starts a supported Python 3.11+ interpreter.
 
     `shutil.which` only proves a file is executable, not that it runs Python. On
     Windows it can return the 0-byte `WindowsApps` App Execution Alias, which
@@ -147,15 +147,20 @@ def _launches_python(py: str) -> bool:
     bakes that path (the PreToolUse hook, the statusline, `/loopx`) then
     silently does nothing."""
     try:
-        return subprocess.run([py, "-c", ""], capture_output=True, timeout=10).returncode == 0
+        return subprocess.run(
+            [py, "-c", "import sys; raise SystemExit(sys.version_info < (3, 11))"],
+            capture_output=True,
+            timeout=10,
+        ).returncode == 0
     except (OSError, subprocess.SubprocessError):
         return False
 
 
 def _python_cmd() -> str:
     """Interpreter to bake into hook / statusline / command strings — robust where
     only `python` (not `python3`) is registered, and where `python3` resolves to a
-    launcher that cannot run Python (the Windows `WindowsApps` alias)."""
+    launcher that cannot run supported Python (including the Windows
+    `WindowsApps` alias and an older PATH interpreter)."""
     for candidate in (shutil.which("python3"), shutil.which("python")):
         if candidate and _launches_python(candidate):
             return candidate

tests/test_claude_goal_install_python_launcher.py

@@ -156,6 +156,42 @@ class Result:
     assert claude_install._launches_python("python3") is True
 
 
+@pytest.mark.parametrize(
+    ("version", "supported"),
+    [((3, 8), False), ((3, 10), False), ((3, 11), True), ((3, 12), True)],
+)
+def test_interpreter_probe_requires_the_supported_python_floor(
+    monkeypatch: pytest.MonkeyPatch, version: tuple[int, int], supported: bool,
+) -> None:
+    real_run = subprocess.run
+
+    def probe(command, **kwargs):
+        # Execute the actual probe with a controlled reported version; no
+        # obsolete Python installation or host configuration is required.
+        return real_run(
+            [sys.executable, "-c", f"import sys; sys.version_info = {version!r}; " + command[2]],
+            **kwargs,
+        )
+
+    monkeypatch.setattr(claude_install.subprocess, "run", probe)
+    assert claude_install._launches_python("candidate-python") is supported
+
+
+def test_python_cmd_skips_a_runnable_but_unsupported_python3(monkeypatch: pytest.MonkeyPatch) -> None:
+    real_run = subprocess.run
+    monkeypatch.setattr(claude_install.shutil, "which", lambda name: name)
+
+    def probe(command, **kwargs):
+        version = (3, 10) if command[0] == "python3" else (3, 11)
+        return real_run(
+            [sys.executable, "-c", f"import sys; sys.version_info = {version!r}; " + command[2]],
+            **kwargs,
+        )
+
+    monkeypatch.setattr(claude_install.subprocess, "run", probe)
+    assert claude_install._python_cmd() == "python"
+
+
 def _literal_interpreter(tmp_path: Path, dirname: str, request: pytest.FixtureRequest) -> Path:
     """A real launcher for `sys.executable` under `tmp_path / dirname`.