Cherry-picked from #1487 by genisis0x and extended with the post-install
subcommand probe per T6 / codex review #19.
`bun install` in $INSTALL_DIR fails on Windows MSYS/MINGW/Cygwin shells
because gbrain's native postinstall script mis-parses path arguments
and aborts with a non-zero exit, breaking gstack-gbrain-install for
Windows users running git-bash/MSYS2. The package installs cleanly
without scripts.
This commit:
- Adds Windows shell detection via `uname -s` matching
MINGW*/MSYS*/CYGWIN*/Windows_NT (#1487's case statement already covers
all four — codex review #18 confirmed MINGW* is included). Windows
paths get `bun install --ignore-scripts`; macOS and Linux unchanged.
- Adds a post-install probe of `gbrain sources --help`. `gbrain --version`
already runs (D19 PATH-shadowing validation), but version success
doesn't prove the subcommand surface is reachable — and
`--ignore-scripts` may have skipped artifacts that subcommands need.
Probe failure logs a clear warning (with Windows-specific remediation
pointing at re-running `bun install` outside MSYS) but does NOT exit
non-zero; users may still get value from gbrain even if the probe
fails transiently.
Refs #1271
Co-Authored-By: Claude <noreply@anthropic.com>