Module filesystem 

Filesystem-backed MemWriter — the gix-free companion to [memstead_git_branch::storage::git_tree::GitTreeMemWriter]. Used by filesystem mems, where entities live as plain files under a workspace root and there is no commit history.

Buffer + commit

Mutations buffer in memory until FilesystemMemWriter::commit. Per-path final-state collapse mirrors the git-tree adapter: a chain of write/delete ops on the same path collapses to a single terminal state by commit time. Move resolves at call-time into a Delete(from) + Upsert(to, bytes) pair — bytes come from the pending buffer when present, otherwise from the live file on disk.

Atomicity

Per-file writes are atomic via write-to-temp + rename. Multi-op commits are not transactional: a failure partway through leaves earlier ops landed and later ops untouched. Single-writer is assumed; concurrent writers against the same mem are out of scope.

CommitId

There is no commit history. [Self::commit] returns a synthetic opaque id (UNIX-nanos + counter, hex) to satisfy the trait surface. Callers that pass this through _hash envelopes get a unique per-commit token but no CAS guarantee — there is no parent state to compare against.

Structs

FilesystemMemWriter

Filesystem-backed MemWriter. Mutations buffer in memory until Self::commit; commit replays them against the directory at root with per-file write-to-temp + rename atomicity.