The platform coverage gates execute only TestCrossPlatformCoverage-named
tests, so the child-move error and dispatch branches that the full local
suite covered incidentally were reported as uncovered changed code on
Windows (96.78% vs the 100% target). Adds a seam-driven edge suite for
the child-move fallback — source/claim/child stat and read failures,
per-child link and symlink collisions and publish failures, rollback
rename failure, foreign-entry abort, mode-restore failure, source shell
removal failure, nested-directory and simulated-symlink children, and
post-rename content drift — plus the retained-destination notice for a
dependent uncertain target in skill setup. The POSIX file identity impl
now consults the lstat seam so its degradation branches are coverable
the same way. Verified against the gate's own changed-line computation:
zero uncovered changed statements in internal/upgrade.
玉澜
fdcaa61587