lsp_cruft

Language server and VS Code extension for the Cruft language (.cruft).

Semantics follow cruftc in the sibling Cruft tree. The server lexes, parses, and type-checks open files, resolves import / use / export against std/ and library paths, and speaks LSP over stdio or VS Code IPC.

Features

Diagnostics — parse and type errors in the editor
Hover — types, signatures, and documentation
Go to definition — jump to declarations
Find references — usages across the workspace
Rename — symbol renaming with conflict checks
Completion — keywords, symbols, and snippets where supported
Signature help — call sites for functions and builtins
Semantic tokens — full and range highlighting from the type checker, including affine, borrowed, shared, arena, and erased HoTT names
Quick fixes — share a moved binding, add a missing import, or switch a static-only var to const
Folding — fold fn / if / while / match / type / scope arena … end regions
Document outline — symbols in the file explorer
Path inspection — hover and CodeLens show path endpoints, normalization steps, and transports. Erased HoTT and interval names are dimmed.
Arena profile — CodeLens on scope arena reports allocation count and a static size estimate. Empty arenas, nested arenas, and unread affine values are warnings.
Typed holes — ? completion can insert a typed literal, refl(...), transport(...), or a call whose parameters and return type match.
Constant evaluation — pure arithmetic, pure calls, and transports get a ▶ CodeLens. The result is also shown as ghost text. Click the lens for the reduction steps.
Architecture views — Command Palette: Cruft: Module Dependency Graph, Cruft: Ownership Flow, Cruft: Arena Topology, and Cruft: Search by Type ((i32, i32): i32 or : i32). Workspace symbol search accepts the same type queries.

Settings

Setting	Description
`cruft.stdPath`	Path to the Cruft standard library tree. Point this at the directory that contains the `std` package (for example the `Cruft/std` folder in a full Cruft checkout).
`cruft.libPaths`	Extra library search paths (array of strings) for resolving `import` / `use`.
`cruft.trace.server`	LSP trace: `off`, `messages`, or `verbose`.

Example (settings.json):

{
  "cruft.stdPath": "C:/path/to/Cruft/std",
  "cruft.libPaths": []
}

Install and run from source

Dependencies
```
cd lsp_cruft
npm install
```
Build
```
npm run build
```
This typechecks the project and bundles it into dist/:
- extension.js — VS Code extension client
- server.js — language server launched by the extension
- cli.js — cruft-lsp command; starts server.js
The language client and server dependencies are bundled, so an installed extension does not need this repository's node_modules.
Package a VSIX
```
npm run package
```
That runs the production build, then vsce package, and writes lsp-cruft-0.1.0.vsix. npx vsce package does the same thing.

Install the .vsix in VS Code, Cursor, VSCodium, or another compatible editor with Extensions: Install from VSIX…. Open a .cruft file to activate the language.
Development host
- Open the lsp_cruft folder in VS Code.
- Run Launch Cruft Extension from the Run and Debug view (F5).
- Open a .cruft file to activate the language.
Other editors

Editors that are not VS Code-compatible can launch the stdio server directly:
```
node dist/cli.js
```
Send the standard library through LSP initializationOptions when the editor does not support VS Code settings:
```
{ "cruft": { "stdPath": "C:/path/to/Cruft/std", "libPaths": [] } }
```

Scripts

Script	Purpose
`npm run build`	Typecheck and bundle into `dist/`
`npm run watch`	Rebuild the bundles on change
`npm run package`	Production bundle, then `vsce package`
`npm test`	Compile and run the checker tests

Layout

src/diag.ts — diagnostic codes, related information, finalize/dedupe pipeline (aligned with cruftc message families)
src/sync.ts — versioned AST synchronization: incremental text edits, decl fingerprints, structural node ids
src/compiler.ts — optional bridge to sibling cruftc --check for authoritative diagnostics
src/lexer.ts, parser.ts, check.ts — Cruft frontend aligned with cruftc (ownership, arenas, cubical HoTT)
src/queries.ts, server.ts, cli.ts — LSP handlers and stdio entry (cruft-lsp)
src/extension.ts — VS Code client (IPC to the bundled dist/server.js)
esbuild.js — bundles the extension and language server for dist/ and the VSIX
syntaxes/cruft.tmLanguage.json — TextMate grammar
language-configuration.json — comments, brackets, indentation, folding

Point cruft.stdPath at Cruft/std (or a checkout that contains mem.cruft). Set cruft.useCompiler to merge diagnostics from a local cruftc build when available.

Cruft