One unreadable tile used to block editing, saving and exporting every open document
(spill::check_integrity was process-global). Add Tile/Surface/Document::scratch_health
(free while no tile has failed) and Document::for_each_surface (ops' history walk now
delegates to it). edit_with checks the document before and after, jobs the document they
captured, import the result, save/export the document written; check_since is now
generation-only so a failure or recovery during an operation refuses it once and a retry
works. Caches check their own sources and purge once per new failure instead of every
frame. Fault-injection tests use a duplicated handle (the Unix file has no name).
Resolve conflicts with main's prefs UI split, session/execute.rs move, GPU memory
budget (gpuMemoryMb, 0 = auto, kept from main) and effective_memory_usage_mb history
budget. Port the Memory Usage % and Scratch Disks preferences into prefs_ui, the edit
integrity guard into session/execute.rs, and adapt main's new pixel readers to the
guarded TileBytes API. Cargo.lock regenerated; scorecard regenerated.
FredApps
vistaero