- lightcraft_catalog::safe_file: one tested helper for crash-safe writes
(temp file in the same folder, sync, rename, folder sync; temp removed on
failure), write_new/write_new_unique that never replace a file and read
the result back, same_file, and a per-thread fault injection for tests.
- engine::originals::OriginalGuard: refuses a write whose target is a
catalogued photo's original or XMP sidecar (by file identity), whatever
the conflict policy or exact path. Used by run_batch (export, Export with
Previous, control/MCP exact paths), ui.render/ui.screenshot paths, merge
previewPath, MCP render_photo/screenshot paths (new query command
export.checkTarget) and lightcraft-cli render.
- The conflict policy now covers an export's sidecars together with the
file (Unique gives both the same free name, Skip skips when either is
taken).
- export::write_file replaces the plain std::fs::write in the desktop app,
CLI, MCP and engine writers; XMP sidecar writes use the shared helper.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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