From 3806a599181fc7e0750f27da17e222fe624e2d31 Mon Sep 17 00:00:00 2001
From: Noor-ul-ain001 <noor01mk@gmail.com>
Date: Wed, 26 Aug 2026 17:41:38 +0500
Subject: [PATCH] fix(events): stop falling back to a fake "pwsh" argv when no
 launcher exists
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`_resolve_event_command_argv`'s `ps` branch did:

    launcher = shutil.which("pwsh") or shutil.which("powershell") or "pwsh"

When neither `pwsh` nor `powershell` is on PATH, this silently returns
`["pwsh", "-File", <script>, ...]` instead of degrading to "no runnable
script" (`None`) like every other failure branch in this same function
(unparseable frontmatter, non-mapping scripts, unresolvable script path,
etc.). `subprocess.run()` then raises `FileNotFoundError` trying to exec a
binary that was just proven absent, which `resolve_and_run_event_command`'s
generic exception handler reports as a confusing
"Event command X error: [Errno 2] No such file or directory: 'pwsh'"
(exit code 2) instead of the clean "No script found for event command"
warning (exit code 0) every other missing-script case gets.

This function is explicitly documented as mirroring the generated
dispatcher's own stdlib-only `_resolve_argv` (same file), which already
gets this right: `if not launcher: return None`. The two had drifted apart.

Fix: mirror that behavior — return `None` when neither launcher is found,
instead of fabricating an argv naming a binary that doesn't exist.

## Test plan
- Added `test_ps_variant_returns_none_when_no_launcher_available` to
  `tests/integrations/test_events.py::TestCommandRunner`: with
  `shutil.which` mocked to return `None` for every name, the resolver must
  return `None` rather than an argv naming a nonexistent `pwsh`.
- Verified the test fails without the fix (test-the-test): it asserted
  `argv is None` but got `['pwsh', '-File', '.../boot.ps1']` — reproducing
  the exact bug.
- Ran the full `tests/integrations/test_events.py` suite: 118 passed, 4
  pre-existing Windows symlink-elevation failures (need admin rights,
  unrelated to this change), 1 skipped.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PJHJ2dHP2RVCNncHqN8Qm9
---
 src/specify_cli/events.py         | 11 ++++++++++-
 tests/integrations/test_events.py | 31 +++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/src/specify_cli/events.py b/src/specify_cli/events.py
index 83da04d4fb..ef298e8cb0 100644
--- a/src/specify_cli/events.py
+++ b/src/specify_cli/events.py
@@ -677,7 +677,16 @@ def _resolve_event_command_argv(
         # subprocess.run(shell=False); invoke via `pwsh -File` (PowerShell 7+),
         # falling back to `powershell -File` (Windows PowerShell) when pwsh is
         # absent (S6). The default Windows script type would otherwise fail.
-        launcher = shutil.which("pwsh") or shutil.which("powershell") or "pwsh"
+        # When NEITHER is on PATH, degrade to "no argv" like every other
+        # failure branch in this resolver (and its documented stdlib mirror,
+        # the generated dispatcher's `_resolve_argv`) — a bare "pwsh" here
+        # would make subprocess.run() raise FileNotFoundError, surfacing as a
+        # confusing "[Errno 2] No such file or directory: 'pwsh'" instead of
+        # the clean "No script found for event command" the caller reports
+        # for a genuinely missing script.
+        launcher = shutil.which("pwsh") or shutil.which("powershell")
+        if not launcher:
+            return None
         return [launcher, "-File", str(script_abs), *rest_args]
 
     # sh: the script is chmod'd executable during install on POSIX. On Windows
diff --git a/tests/integrations/test_events.py b/tests/integrations/test_events.py
index f74aeaaa36..ba6deb12c0 100644
--- a/tests/integrations/test_events.py
+++ b/tests/integrations/test_events.py
@@ -1340,6 +1340,37 @@ def test_ps_variant_prefixed_with_powershell_launcher(self, tmp_path):
         assert argv[1] == "-File"
         assert PurePath(argv[2]).as_posix().endswith(".specify/scripts/powershell/boot.ps1")
 
+    def test_ps_variant_returns_none_when_no_launcher_available(self, tmp_path, monkeypatch):
+        """When NEITHER pwsh nor powershell is on PATH, the resolver must
+        degrade to "no argv" like every other failure branch in this
+        function — not fall back to a bare "pwsh" string, which would make
+        subprocess.run() raise FileNotFoundError instead of the caller's
+        clean "No script found for event command" warning.
+
+        The generated dispatcher's documented stdlib mirror, `_resolve_argv`,
+        already does this correctly (`if not launcher: return None`).
+        """
+        from specify_cli.events import _resolve_event_command_argv
+        import shutil as _shutil
+
+        cmd_dir = tmp_path / ".specify" / "templates" / "commands"
+        cmd_dir.mkdir(parents=True)
+        (cmd_dir / "boot.md").write_text(
+            "---\n"
+            "description: \"Boot\"\n"
+            "scripts:\n"
+            "  ps: scripts/powershell/boot.ps1\n"
+            "---\nBody\n",
+            encoding="utf-8",
+        )
+        ps_dir = tmp_path / ".specify" / "scripts" / "powershell"
+        ps_dir.mkdir(parents=True)
+        (ps_dir / "boot.ps1").write_text("exit 0\n", encoding="utf-8")
+
+        monkeypatch.setattr(_shutil, "which", lambda name: None)
+        argv = _resolve_event_command_argv(cmd_dir / "boot.md", tmp_path, None)
+        assert argv is None
+
     def test_run_command_executes_with_project_root_cwd(self, tmp_path):
         """R1: the event command runs with cwd set to the project root, not the
         caller's arbitrary working directory, so project-relative script logic