TODO: Describe the main failure classes: recoverable document conversion failures, OCaml exceptions, worker cancellation, SQLite busy/transaction failures, native crashes, and apparent UI freezes.
TODO: Describe exclusive connection checkout,
FULLMUTEXconnections, statement finalization, transaction cleanup, bounded busy retries, and connection disposal after callback failure.
TODO: Describe worker exception capture, preservation of raw backtraces, debug-log reporting, and why native signals require core dumps rather than OCaml exception handling.
TODO: Document the investigation from a rare SIGSEGV, through the
sqlite3_finalize/invalid-mutex backtrace, to the sqlite3-ocaml 5.4.2 GC-rooting fix and the raised dependency floor.
TODO: Describe unit and expect tests for search behavior, cram tests for complete CLI workflows and exit statuses, and clean container builds for native dependency changes.
TODO: Summarise what the hardening work changed, which risks are intentionally accepted, and what diagnostics remain available if another rare freeze or native crash occurs.