{"id":"macos-fsync-not-durable","text":"On the development platform (Darwin/APFS), `os.fsync()` may not flush the disk write cache; true durability requires `fcntl(fd, F_FULLFSYNC)`, which is never used at any of the 13 fsync call sites in the codebase.","truth_value":"IN","source":"entries/2026/05/29/topic-posix-durability-guarantees.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{},"explanation":{"steps":[{"node":"macos-fsync-not-durable","truth_value":"IN","reason":"premise"}]}}