Editor Integration (LSP)

Resilient ships an opt-in Language Server that wires up red-squiggle diagnostics, hover, go-to-definition, and completion in any editor that speaks LSP.

Table of contents

• Build
• Start the server
• What’s implemented
  • Diagnostics
  • Hover
  • Go-to-definition
  • Completion
• Editor setup
  • Neovim (nvim-lspconfig)
  • VS Code
• Semantic tokens
• What’s next

---

Build

The LSP server pulls in tower-lsp + tokio, so it’s gated behind a feature flag. Default builds don’t pay the cost.

cd resilient
cargo build --features lsp --release
# Binary: resilient/target/release/resilient

Running resilient --lsp without the feature emits a helpful error and exits non-zero.

Start the server

resilient --lsp

The server communicates over stdin/stdout using the standard JSON-RPC LSP framing. Your editor client manages the process.

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What’s implemented

Diagnostics

Every did_open or did_change event re-runs the full parse + typecheck pipeline and publishes structured diagnostics with <uri>:<line>:<col>: locations. Editor squiggles appear in the correct column for type errors. Parser errors currently appear at line 1, column 1 — finer-grained parser spans land in a follow-up.

Hover

Hovering over any literal token shows its type:

Literal	Hover shows
42	int
3.14	float
"hi"	string
true	bool

Hover over identifiers (variables, functions) is a planned follow-up that depends on the full type-inference pass.

Go-to-definition

Clicking “go to definition” on any top-level function or struct name jumps to its declaration site. Works across a single file; multi-file workspace lookup is a follow-up.

Completion

Triggering completion offers:

1. All built-in functions, alphabetical (abs, ceil, floor, …).
2. Every top-level declaration in the current file (functions, structs, type aliases), alphabetical after builtins.

Scope-aware local-variable completion and post-dot field completion are follow-up tickets.

---

Editor setup

Neovim (nvim-lspconfig)

local lspconfig = require("lspconfig")
local configs   = require("lspconfig.configs")

if not configs.resilient then
  configs.resilient = {
    default_config = {
      cmd      = { "/absolute/path/to/resilient", "--lsp" },
      filetypes = { "rust" },   -- .rs files; change to "resilient" if you register a custom filetype
      root_dir  = lspconfig.util.root_pattern("Cargo.toml", ".git"),
      settings  = {},
    },
  }
end
lspconfig.resilient.setup({})

Replace /absolute/path/to/resilient with the path to your built binary (e.g. ~/GitHub/Resilient/resilient/target/release/resilient).

VS Code

Use the bundled vscode-extension/ or any generic LSP runner extension (e.g. Generic LSP Client). Point command at the Resilient binary with --lsp as the argument and set the language ID to rust (or register a custom resilient language ID).

The vscode-extension/ directory in the repo contains a minimal extension scaffold — npm install && vsce package inside it produces an installable .vsix.

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Semantic tokens

The server also serves textDocument/semanticTokens/full — editors that support semantic highlighting will color keywords, literals, type names, and function calls distinctly beyond what syntax highlighting alone provides.

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What’s next

• Hover for identifiers (variables, parameters, function names).
• Scope-aware local-variable completion.
• Post-dot field completion for structs.
• Finer-grained parser error positions.
• Multi-file workspace go-to-definition.