LSP module infrastructure

March 29, 2026 · View on GitHub

Overview

Foundation for a Language Server Protocol client in Ferrite: a background worker with mpsc channels, JSON-RPC stdio framing (Content-Length headers), extension-to-server hints, and ServerStatus tracking. Editor features (diagnostics, completions, initialize handshake) are deferred to later tasks; Task 24+ wires lifecycle to workspaces.

Key Files

  • src/lsp/mod.rs — Public exports; #![allow(dead_code)] until UI calls the API each frame.
  • src/lsp/state.rs — ServerStatus enum.
  • src/lsp/detection.rs — LspServerSpec, detect_lsp_server_for_path().
  • src/lsp/transport.rs — Framing helpers and MessageReader for incremental reads.
  • src/lsp/manager.rs — LspManager, worker thread, process spawn, stdout/stderr drains.
  • src/state.rs — AppState::lsp: LspManager.

Implementation Details

  • Threading: One dedicated worker thread owns HashMap of child processes; UI sends Start / Stop / Restart / Shutdown via mpsc.
  • Transport: Messages are UTF-8 JSON bodies prefixed with Content-Length: <n>\r\n\r\n per LSP spec.
  • Pipes: Stdout/stderr are read on helper threads so servers cannot deadlock on full pipes before protocol I/O is implemented.
  • Detection: Built-in mappings (e.g. .rs → rust-analyzer) are defaults only; user overrides belong in settings later.

Dependencies Used

  • serde_json — Serialize/deserialize JSON-RPC payloads as serde_json::Value in the transport layer.
  • std — mpsc, process, thread, io (no extra LSP crates yet).

Usage

  • Obtain the manager from app_state.lsp.
  • Call start_server(key, spec) with a key such as "rust" and an LspServerSpec from detect_lsp_server_for_path or custom paths.
  • Each frame (or on idle), poll_events() and handle LspManagerEvent::StatusChanged for UI/status bar.