Beacon Language Server

Beacon's Language Server Protocol (LSP) implementation bridges the Rust-based analyzer with editors such as Zed, VSCode/VSCodium, Neovim, and Helix. This chapter documents the system from high-level goals to feature-by-feature behaviour.

LSP Capabilities Quick Reference

Beacon implements the following LSP features:

• Diagnostics: Real-time syntax, semantic, and type error reporting
• Hover: Context-sensitive type information and documentation
• Completion: Symbol table-based completions
• Navigation: Go to definition, type definition, implementation (cross-file), find references, document highlights
• Symbols: Document outline and workspace fuzzy search
• Semantic tokens and inlay hints
• Refactoring: Rename (cross-file), extract function/variable, inline function, change signature, move symbol, code actions, quick fixes

See Feature Providers for detailed implementation.

Documentation Overview

Use the sidebar to jump into any topic, or start with the sections below:

• Goals And Scope - what the server delivers today and what is intentionally out of scope.
• Architecture Overview - how shared state, concurrency, and feature wiring are structured.
• Document Pipeline - how file contents become parse trees, ASTs, and symbol tables.
• Caching - multi-layer cache architecture and invalidation strategies for fast incremental updates.
• Feature Providers - the capabilities exposed via LSP requests and notifications.
• Request Lifecycles - end-to-end flows for initialization, diagnostics, completions, and more.
• Workspace Services - cross-file features and emerging workspace indexing plans.
• Testing Strategy - automated coverage for providers and backend flows.
• Current Limitations - known gaps and trade-offs in the current implementation.
• Next Steps - near-term improvements on the roadmap.

If you are new to the Language Server Protocol itself, read the primer in Learn → Language Server Protocol before diving into these implementation details.