@arvoretech/pi-lsp

PI extension that bridges Language Server Protocol servers, giving the agent real compiler diagnostics, go-to-definition, find-references, hover types and project-wide rename — instead of guessing from text.

Tools

Tool	Purpose
lsp_diagnostics	Real type-checker errors/warnings for a file (e.g. TS2345).
lsp_definition	Resolve a symbol to its definition (1-based line/column).
lsp_references	Find all references to a symbol across the project.
lsp_hover	Inferred type signature and docs for a symbol.
lsp_rename	Compute a safe project-wide rename. Returns edits; does not apply them.

Commands

• /lsp-status — list configured language servers and their file extensions.

Supported languages

Driven by a registry (src/registry.ts). Currently:

• TypeScript / JavaScript (.ts .tsx .js .jsx .mts .cts .mjs .cjs) via typescript-language-server --stdio.

Adding a language is a single entry in LANGUAGE_SERVERS — the JSON-RPC client, lifecycle, and document sync are language-agnostic.

Requirements

The language server binary must be on PATH. For TS/JS:

pnpm add -g typescript-language-server typescript

If a server is missing, the tools return a clear message and the extension stays inert (no crash).

How it works

• One server instance per (language, project root), lazy-spawned on first use. Root is detected by walking up from the file and preferring the nearest tsconfig.json / jsconfig.json / package.json over .git, so files inside a subproject of a monorepo resolve to the subproject (which has its own TypeScript install) rather than the repo root.
• If a server fails to initialize (e.g. no TypeScript found at the resolved root), the instance is not cached as permanently unavailable — a later call can retry once the root resolution improves.
• Documents are synced (didOpen / didChange) from disk on each call; diagnostics are awaited with a short quiet-period debounce.
• Servers are shut down cleanly on session_shutdown.

Architecture

src/
  protocol.ts   LSP type subset
  client.ts     JSON-RPC over stdio (Content-Length framing, request/notify)
  registry.ts   language -> server config
  manager.ts    spawn / lifecycle / root detection / doc sync / high-level ops
  tools.ts      lsp_* tool definitions + output formatting
  index.ts      entry shell (lifecycle + tool registration)