Replace configuration-specific write-file-atomic delegation with a verified
input snapshot, exclusive private staging, and an explicit canonical-parent
destination. Existing files publish by rename; first-run files use an exclusive
link so a newly created destination is retained. Both consumers read back the
publication owner's selected path.
Retain descriptor and staging cleanup capabilities through recovery and host
retry. Preserve mode and ownership, remove temporary permission handoffs, and
use positional restoration writes. Keep UTF-8 diagnostics with failed cleanup.
Validation: 284 focused tests passed, one skipped across 14 files; check:fast,
format:check, docs:check (including five consistency tests), two source reviews,
and 12 completed isolated public CLI setup/uninstall cost controls passed.
Native Windows/Linux, real editor concurrency, and providers were not verified.
Final-check/publication races and same-inode concurrent writers remain unexcluded.
Fixes#4904
Replace pathname writes with the shared configuration publication owner.
Reject replacement readback and restore through the exact staged descriptor.
Retain initial-read, readback and publication cleanup owners for retry. Share
nested cleanup handling with setup without granting authority to opaque
cancellation reasons. Separate host admission from nested file cleanup gates.
Preserve uninstall file modes, including readable read-only configurations.
Hold the exact staging permission owner through writable-descriptor handoff
and failed mode restoration. Remove the superseded writeText effect contract.
Validation: 206 focused tests across 9 files, check:fast, formatting and
docs:check passed. Three uninstall replacement controls fail on baseline
7e4eed9dd while thirteen setup controls pass. Twelve completed CLI uninstall
tasks preserve equivalent outputs, config, backups and modes0400/0640.
Two read-only source reviews completed. Native Windows/Linux and real editor
races remain unverified; in-place writer exclusion is still not provided.
Closes#4902
Add cases where the backup copy reports success but leaves the recovery
file missing or holding other bytes; uninstall must fail before writing.
Narrow the installation guide so it promises a backup path only for the
failures that report one.
(cherry picked from commit 70bff72403)
morluto