nc://lsp

A Nodecode cell that puts language servers behind the model's eval. With it, an eval that writes a file through edit or write-file ends with what the servers say about that file:

wrote src/a.py: 5 lines, 64 characters
LSP diagnostics (1 error):
src/a.py:5:11 [error] [Pyright] Type "int" is not assignable to declared type "str" (reportAssignmentType)

and the model gets a few verbs in the lsp: package:

(lsp:diagnostics "src/a.rs")                     ; every diagnostic, or OK; a list of paths for several
(lsp:definition "src/a.rs" "parse" :line 40)     ; where it is defined, with the line
(lsp:references "src/a.rs" "parse")              ; every use, the declaration included
(lsp:hover "src/a.rs" "parse")                   ; its type and docs
(lsp:symbols "src/a.rs")                         ; the file's outline; :query "Parser" searches the project
(lsp:rename "src/a.rs" "parse" "parse_all")      ; renames across files and writes them; :apply nil previews
(lsp:status)  (lsp:restart)                      ; what runs, and starting over
(lsp:request "rust-analyzer" "rust-analyzer/expandMacro" :params p :path "src/a.rs")

A symbol is found in the file by name: its first mention, "parse#2" the second, :line N on that line. (help :lsp) is the model's manual.

Ported from oh-my-pi's lsp module: its 55 server definitions (servers.json, omp's defaults.json), its server selection and root markers, its diagnostics wait and output format. See NOTICE.

How it runs

• A server starts the first time a file it serves is written or asked about, from the project's own bins (node_modules/.bin, .venv/bin, ...) or PATH, in the project root its markers name: the outermost directory holding one inside the session's repository, else the nearest. Every session working there shares it. It stops after idle_minutes unused, or when the cell stops.
• A file gets every server whose file types name it, type checkers before linters. Diagnostics after a write come from all of them; the verbs ask the first.
• The diagnostics after a write wait at most wait_ms (3 s) for the servers. A server that has not answered by then says lsp: NAME still checking FILE; (lsp:diagnostics "FILE") for the result. At most 50 diagnostics and 4,000 characters, errors and warnings only, the first line of each message. A clean file adds nothing.
• A verb waits at most 8 s, inside the eval's ten-second yield window; a project still loading answers still indexing; try again.
• A server's stderr goes to ~/.nodecode/lsp/NAME.log. A server that fails to start says why, with the last lines it printed, and is tried again 30 s later.

Nothing here edits the core: the cell hooks write-file-text, the one atomic writer under edit and write-file, and the :tool point.

Install

Copy this folder into ~/.nodecode/cells/nodecode-lsp/ and restart Nodecode, or run (restart-cells). Install the language servers you want the usual way (npm i -g pyright, rustup component add rust-analyzer, ...); the cell starts only what it finds.

Configure

Optional. The section is on unless it says "enabled": false:

{
  "lsp": {
    "diagnostics_on_write": true,   // append diagnostics to an eval that wrote files
    "wait_ms": 3000,                // how long that waits for them
    "idle_minutes": 15,             // stop a server unused this long
    "servers": {
      // override one of the 55 by name: any member, the rest kept
      "pyright": { "command": "/opt/pyright/bin/pyright-langserver" },
      "ruff": { "disabled": true },
      // or add one
      "my-ls": { "command": "my-ls", "args": ["--stdio"],
                 "file_types": [".xyz"], "root_markers": [".git"],
                 "settings": {}, "init_options": {} }
    }
  }
}

config.example.jsonc has the whole section.

Test

From this repository's root:

tools/test-cell.sh nodecode-lsp

The tests drive test/fake-server.py, a scripted language server, through python3; nothing touches the network.

Gaps

What omp's module does that v1 does not:

• Format on write, code actions, rename_file. omp formats a written file through the server, offers quick fixes and import organizing, and renames a file with the server updating its importers. A rename here edits text only: one that would also create, rename or delete a file is refused.
• Late diagnostics. omp waits 500 ms inline and delivers a slow server's diagnostics into the next turn. Here the write waits wait_ms and a slow server says "still checking"; the model asks again with lsp:diagnostics.
• The biome and swiftlint clients, and file: "*" checkers. omp drives those two through their CLIs rather than LSP, and can check every file a glob names; the cell skips both servers and checks named files.
• The diagnostics dedup ledger. omp suppresses a diagnostic it already showed for an unchanged file; here every write reports what stands.
• The mux daemon and lspmux. Not needed: the gateway is one long-lived process, so a server is already shared by every session in its root.

MIT licensed.