`graphify hook install` emitted `_PINNED=''` for some Windows uv-tool installs,
so every interpreter probe failed, each commit printed "could not locate a
Python with graphify installed" and the graph never rebuilt.
Root cause is the install-time allowlist in `_pinned_python()`, not the uv
layout: it accepted `[a-zA-Z0-9/_.@:\-]` but not a plain space, so any
`sys.executable` under a profile whose name contains one -- `C:\Users\First
Last\AppData\Roaming\uv\tools\graphifyy\Scripts\python.exe`, or the equally
common `C:\Program Files\Python312\python.exe` -- was rejected wholesale and
nothing was recorded. A space-free Windows uv path pins correctly, which is why
this looks layout-specific.
A space is safe to allow because every consumer already quotes the value: the
hook scripts embed it as `_PINNED='<path>'` and dereference `"$_PINNED"`, so a
space can neither split a word nor start a command. Adding it to the allowlist
therefore fixes the pin without weakening the injection guard -- `$`, backtick,
`;`, `'` and `"` are all still rejected.
`_register_merge_driver` did interpolate the path unquoted into the
`merge.graphify.driver` command, which git runs through a shell; that would
split a spaced path into two words, so it is now double-quoted. Double quotes
are safe here precisely because the allowlist keeps `$` and backticks out.
Tests: spaced Windows/POSIX paths are pinned; metacharacter paths are still
rejected (including `'` and `"`); the merge driver quotes a spaced interpreter;
and the installed post-commit/post-checkout hooks carry the real path rather
than `_PINNED=''`.
Souptik Chakraborty
cfe15f9161