The legacy hook scripts `hooks/mempal_save_hook.sh` and
`hooks/mempal_precompact_hook.sh` shell out to `python3` for JSON
parsing and transcript-message counting. On macOS GUI launches of
Claude Code — `open -a`, Spotlight, the dock — the harness inherits
`PATH` from launchd (`/usr/bin:/bin:/usr/sbin:/sbin`), which may not
contain a `python3` at all, or may contain only a system Python that
lacks what the hook needs. The hook then fails silently in the
background log where users never look.
`mempalace` auto-ingest itself is unaffected — #340 switched that
path to the `mempalace` CLI entry point, which pipx/uv install on a
stable global PATH.
This PR adds a `MEMPAL_PYTHON` environment variable that users can
set to point the hook at any Python 3 interpreter. Resolution order
applied at each `python3` invocation site inside the two hooks:
1. $MEMPAL_PYTHON (if set and executable)
2. $(command -v python3) on PATH
3. bare `python3` as a last resort
The interpreter does not need `mempalace` installed in it — only the
standard-library `json` and `sys` modules. The hook's `mempalace mine`
call runs via the CLI, independent of this override.
hooks/README.md documents the macOS GUI PATH issue and the
MEMPAL_PYTHON override. tests/test_hooks_shell.py adds 3 regression
tests (Linux/macOS only, POSIX bash):
- MEMPAL_PYTHON override wins over PATH (proved via a
marker-emitting shim that proxies to the real interpreter).
- Non-executable MEMPAL_PYTHON falls back to PATH rather than
crashing on permission denied.
- Unset MEMPAL_PYTHON resolves via PATH.
`hooks_cli.py` (the Python implementation invoked via
`mempalace hook run ...`) already uses `sys.executable` and is
therefore trivially correct — no changes needed there.
Supersedes abandoned branch `fix/hook-bugs`.
Co-Authored-By: MSL <232237854+milla-jovovich@users.noreply.github.com>
Igor Lins e Silva