ffs is a FUSE-based filesystem that mounts semi-structured data formats (JSON, TOML, YAML) as a Unix directory tree, enabling interactive editing with standard shell commands (cat, echo, mv, rm, mkdir). It includes companion tools pack (directory tree → data format) and unpack (data format → directory tree). The system is implemented in Rust with a modular architecture: the nodelike crate provides a generic trait and Node enum for format-agnostic representation, while ffs handles FUSE mount logic and pack/unpack handle batch conversion. Key features include lazy/eager loading strategies, name munging for special characters, extended attribute support, and format conversion (e.g., JSON to YAML). The repository also contains an extensive benchmark suite using real-world datasets (FDA, GitHub, NOAA, etc.) to compare loading strategies. While the core functionality is complete and well-tested with over 60 integration test scripts, the project appears to be in a stale maintenance state with no recent commits (last significant activity in 2021) and several open issues. The codebase demonstrates good software engineering practices (modular design, comprehensive tests, performance instrumentation) but has limited reuse potential beyond its specific domain of semi-structured data manipulation via filesystem semantics.