Language servers

snowpea talks to the same language servers your editor does. When you save a file, the agent sees the type errors; when it is about to rename something, it can ask the compiler who uses it instead of guessing from a grep.

Other languages: 한국어 · all pages

What it changes

Two things, and you get both without configuring anything.

Every write_file and edit_file result carries a Diagnostics block when a server is running for that file:

replaced 1 occurrence(s) in src/app.py

<diagnostics file="src/app.py">
ERROR [42:5] "userId" is not defined (reportUndefinedVariable)
WARN [3:1] Import "os" is not accessed (reportUnusedImport)
</diagnostics>

The agent reads that before it moves on, so a typo is caught in the same turn it was introduced rather than three tool calls later when the tests run.

Seven tools are available to the agent:

Tool	What it answers
lsp_diagnostics	what is wrong with a file, or with everything seen so far
lsp_definition	where the symbol at this position is defined
lsp_references	every use of the symbol at this position, project-wide
lsp_symbols	an outline of one file
lsp_workspace_symbols	find a class or function by name, anywhere
lsp_hover	the type and docs for the symbol at this position
lsp_rename	rename the symbol everywhere and write the files

All of them are read except lsp_rename, which is a write and is refused in plan mode like any other write.

snowpea tools list --json

Which servers

snowpea knows about the servers below. It starts one the first time a file it serves is touched, in that file's project root, and shuts it down again after ten idle minutes.

typescript, deno, vue, eslint, biome, oxlint, gopls, ruby-lsp, pyright, ruff, ty, elixir-ls, zls, csharp, fsharp, sourcekit-lsp, rust, clangd, svelte, astro, yaml-ls, lua-ls, bash, dockerfile, terraform, dart, ocaml-lsp, gleam, clojure-lsp, nixd, prisma, haskell-language-server, julials.

A server is used only if its binary is already on your PATH. Nothing is downloaded unless you ask for it, and a missing server is never an error — you just get no diagnostics for that language.

ruff and ty are off by default because pyright already claims .py, and running two Python servers over every edit doubles the wait for one set of answers. Turn one on by naming it in lsp.servers.

Seeing what is running

The daemon answers lsp.status with one row per server — its id, its project root, its state (starting, ready, broken or stopped) and its pid while it is up. Any client on the protocol can ask; the terminal UI's /lsp view and the IDE's LSP card both read it.

A server that failed twice is reported broken and is not started again for the life of the daemon: fix the install, then restart it.

lsp.status only knows about servers that a root has actually spawned. To see every server snowpea could run — without touching a file first — ask lsp.catalog: one row per registered id with its languageIds, extensions, whether it is installable (autoInstall could obtain it with npm/pip/go) with an installHint command for doing that by hand, and whether it is currently disabled (off by default, named in lsp.disabled, or disabled through an lsp.servers override). This is what a settings screen's LSP card lists before anything has started.

snowpea daemon stop
snowpea daemon start

Settings

Everything lives under lsp in $SNOWPEA_HOME/settings.json and is picked up without a restart.

{
  "lsp": {
    "enabled": true,
    "autoInstall": false,
    "disabled": ["eslint"],
    "idleTimeoutSec": 600,
    "servers": {
      "clangd": { "command": ["clangd", "--header-insertion=never"] },
      "zig": { "command": ["zls"], "extensions": [".zig"] }
    }
  }
}

Key	Default	What it does
enabled	true	false removes the seven tools from the agent's list and stops the Diagnostics block
autoInstall	false	true lets snowpea install a missing server with npm, pip or go into $SNOWPEA_HOME/lsp
disabled	[]	server ids to leave alone
servers	{}	define a new server, or replace a builtin's command
idleTimeoutSec	600	seconds a server may sit unused before it is stopped; 0 keeps them all alive

A servers entry takes command (required, an argv list), extensions, rootMarkers, env and initialization. Naming an id that already exists replaces that server's command and leaves the rest of its definition alone, which is how you point pyright at a wrapper script.

Set "enabled": false in that file to turn the whole thing off.

Why a language is quiet

In order, the things to check:

1. The binary is not on PATH. which pyright-langserver, which gopls. snowpea does not search anywhere else unless autoInstall is on.
2. The project root has no marker. Each server looks upwards from the edited file for its own markers — go.mod for gopls, Cargo.toml for rust-analyzer, pyproject.toml for pyright, a lockfile for the JavaScript servers. Without one, strict servers (rust, deno, biome, oxlint) decline the file entirely.
3. TypeScript needs the workspace's own TypeScript. typescript-language-server and astro-ls exit during startup unless node_modules/typescript/lib/tsserver.js exists, so snowpea does not start them until it does. Run your install first.
4. The server is still starting. An edit waits at most three seconds for a server to come up. A cold pyright or rust-analyzer takes longer than that, so the first edit in a fresh session can come back without a block and the next one will have it.
5. It crashed. lsp.status says broken.

Security

Every server is started with an argument list, never a shell command line, so nothing in a filename or a setting can be interpreted as a command. With autoInstall left at its default false, the LSP layer makes no network request of any kind.