lsp-client

lsp-client

LSP client library for providing code intelligence to the LLM agent. Manages LSP server lifecycles and communicates over JSON-RPC/stdio, reusing the user's Neovim LSP configuration so no manual server setup is required.

Architecture

tcode (startup)
  |
  +-- extract_config_from_nvim()  // headless nvim discovers installed servers
  |
  +-- LspManager::new(config, root_dir)
        |
        +-- LspServer::start()    // spawns server process, performs initialize handshake
              |
              +-- LspTransport    // JSON-RPC framing over stdin/stdout

tcode creates an LspManager at startup and passes it (via Arc) to the tools crate, which exposes it as the LSP tool.

Advertised Client Capabilities

The client advertises support for:

• textDocument/definition (go-to-definition)
• textDocument/references (find references)
• textDocument/hover (type info, documentation)
• textDocument/documentSymbol (hierarchical symbols in a file)
• textDocument/implementation (go-to-implementation)
• textDocument/callHierarchy (incoming/outgoing calls)
• workspace/symbol (project-wide symbol search)
• window/workDoneProgress (progress tracking)

Modules

config

LSP configuration extraction from Neovim. Runs nvim --headless with an embedded Lua script that queries vim.lsp.config and vim.filetype.match to produce a JSON manifest of:

• Server names, commands, filetypes, root markers
• Server settings and init options
• File extension to filetype mappings

Falls back to an empty config on any failure (nvim not installed, timeout, parse error).

manager

LspManager owns the config and a map of running server instances. Key behaviors:

• Lazy start: get_or_start_server(filetype) spawns a server on first use for a given filetype
• Root detection: walks up from project dir looking for root markers (e.g. Cargo.toml, go.mod)
• Pre-warming: pre_warm() detects project type from marker files and eagerly starts relevant servers
• Shutdown: shutdown_all() sends the LSP shutdown/exit sequence to all running servers

server

LspServer wraps a single running LSP server process. Handles:

• The initialize / initialized handshake
• Typed request/response via request::<R>(params) using lsp-types trait bounds
• Typed notifications via notify::<N>(params)
• Convenience methods: open_file(), close_file()
• Server capability and progress inspection
• rust-analyzer special-casing: injects checkOnSave: false to avoid heavy background checks

transport

LspTransport implements the JSON-RPC over stdio protocol:

• Content-Length framed message reading/writing
• Background reader task that dispatches responses to waiting oneshot channels
• Auto-replies to server-initiated requests (e.g. window/workDoneProgress/create)
• ProgressTracker for monitoring server indexing/loading state
• 30-second request timeout with automatic cleanup
• Clean shutdown with process kill on drop

Dependencies

Crate	Purpose
lsp-types	LSP protocol type definitions
tokio	Async runtime, process spawning, IO
serde / serde_json	JSON-RPC serialization
parking_lot	Fast synchronous mutexes (progress tracker)
url	File path to URI conversion
anyhow	Error handling
tracing	Structured logging