Module fsx 

fsx — the one atomic, durable file write for db.md’s primary data.

Every store-state file that holds primary data — content records (crate::parser::write_file), log.md and its archives (crate::log), and in-place link rewrites — is replaced through write_atomic:

1. write the bytes to a uniquely-named sibling temp file in the same directory (create_new, so a predictable temp name can never be clobbered — closing the temp-clobber race);
2. fsync the temp file;
3. rename it over the destination (atomic on a single filesystem, so a concurrent reader never observes a half-written file);
4. fsync the parent directory so the rename survives a crash.

This is the single primitive for durable writes — never std::fs::write, which is neither atomic nor crash-durable.

Not for the index. index.md / index.jsonl are derived, rebuildable artifacts on the O(changed) write-through path; they use their own atomic-but-not-fsync’d writer (crate::index’s AtomicTemp) on purpose — a crash-lost index write is recovered by dbmd index rebuild, so paying an fsync per catalog update on the hot loop would be cost without benefit.

Functions

write_atomic

Atomically and durably replace path with bytes (see the module docs for the write/fsync/rename/fsync sequence). The parent directory is created if missing. On a rename failure the temp file is cleaned up rather than leaked.