* feat(#1679): confine install writes within configHome
ADR-1239 Phase B write-confinement: a pure assertDestWithinConfigHome(configDir, destSubpath) rejects a destSubpath that escapes configHome (path traversal / NUL byte) at plan-build time on BOTH the install and uninstall plan paths; surface.applySurface and installOpencodeFamilySkills route through it, and _copyStaged carries a defense-in-depth containment check. Security-load-bearing for the Phase C third-party-descriptor loader.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
* docs(#1704): add changeset for destSubpath write-confinement
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
* test(#1704): fix windows path-portability in confinement test
The N1 'accepts a true child subpath' assertion compared against path.join (no drive resolution) while the helper uses path.resolve — on Windows that mismatches the C: drive prefix. Compute the expected via path.resolve to mirror the helper. Windows-CI-only failure (local gsd-test is Mac+Linux).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>