This is a Rust library (`kdl`) for parsing, manipulating, and serializing the KDL Document Language. It provides a fully round-trip-preserving parser (formatting, whitespace, comments) supporting both KDL v2 and, optionally, v1. The library exposes a rich AST (`KdlDocument`, `KdlNode`, `KdlEntry`, `KdlIdentifier`, `KdlValue`) with builder patterns and formatting configuration. It integrates with `serde` for deserializing/serializing Rust types from/to KDL, using a well-documented mapping convention (e.g., `#args`, `#rest`, property renames via `#@`). Error handling is implemented via `miette` for rich diagnostics. The repository also includes a language server (`kdl-lsp`) based on `tower-lsp` that provides diagnostics for KDL files, though incomplete. Comprehensive compliance tests (hundreds of input/expected KDL files) ensure spec adherence. The architecture is a single library crate with optional serde support, a separate v1 fallback crate, and an LSP tool. The core parser uses `winnow` with error recovery. Dead code from a disabled KQL query engine exists, and serde support is marked experimental, indicating some technical drift. Overall, it's a high-quality, professionally engineered library with excellent test coverage and well-thought-out abstractions.