user lsp

LSP code intelligence

Steiner can connect to language servers so the model can navigate code and read diagnostics. LSP is off by default. Set lsp.enabled: true and configure at least one server under lsp.servers. Field reference: lsp block.

Tools

Tool	Purpose
lsp_definitions	Jump to a symbol's definition.
lsp_implementations	Find concrete implementations of an interface or interface method.
lsp_type_definitions	Jump to the type declaration of a variable, field, or parameter.
lsp_references	Find references to a symbol, including its declaration unless include_declaration is false.
lsp_diagnostics	Get errors, warnings, information, and hints for a file.
lsp_hover	Get a symbol's signature and documentation, cut at 4000 characters.
lsp_symbols	Search workspace symbols with query, outline a file with file, or pass both to filter a file's outline.

The position tools (lsp_definitions, lsp_implementations, lsp_type_definitions, lsp_references, lsp_hover) take either a 1-based line and column, or a symbol name optionally narrowed by line. Without line, an ambiguous symbol returns the candidate lines.

The tools are registered whenever lsp.enabled is true. Results are capped by lsp.max_results and can be incomplete while a server is still indexing. When no server handles a file, a server failed to start, or a server does not support a request, the tool returns an explanatory message instead of failing.

Some sub-agent types also get these tools when at least one server is configured; see Sub-agent delegation.

Server setup

Steiner does not install language servers. Install each one yourself, then point command at it. Each file extension should belong to one enabled server.

gopls (Go)

lsp:
  enabled: true
  servers:
    gopls:
      enabled: true
      command: gopls
      file_extensions: [".go"]
      root_markers: ["go.mod", ".git"]

Install: go install golang.org/x/tools/gopls@latest

typescript-language-server (TypeScript and JavaScript)

lsp:
  enabled: true
  servers:
    tsserver:
      enabled: true
      command: typescript-language-server
      args: ["--stdio"]
      file_extensions: [".ts", ".tsx", ".js", ".jsx"]
      root_markers: ["package.json", "tsconfig.json"]

Install: npm install -g typescript-language-server typescript

pyright (Python)

lsp:
  enabled: true
  servers:
    pyright:
      enabled: true
      command: pyright-langserver
      args: ["--stdio"]
      file_extensions: [".py"]
      root_markers: ["pyproject.toml", "setup.py", ".git"]

Install: pip install pyright, or use your package manager.

rust-analyzer (Rust)

lsp:
  enabled: true
  servers:
    rust-analyzer:
      enabled: true
      command: rust-analyzer
      file_extensions: [".rs"]
      root_markers: ["Cargo.toml", ".git"]

Install: see the rust-analyzer manual.

initialization_options is passed to the server as given when it starts.

Environment and sandbox

Steiner builds the server environment from its own environment and the server's env map. When the sandbox is active, it filters that environment, including env entries, through the sandbox allowlist. Add other variable names to sandbox.env_passthrough to pass them through. The sandbox gives the server a read-only project. See Sandboxing.

Lifecycle

• A server starts on the first tool call that needs it, waits up to lsp.ready_timeout to finish starting, and stops after lsp.idle_timeout without requests.
• Each request is bounded by lsp.request_timeout.
• A server that crashes is started again on the next call. A server that fails to start is retried after 30 seconds.
• /lsp in the TUI lists running and configured servers. The sidebar shows an LSP row once a server is active: green when ready, a spinner while starting, red after a failure.

Diagnostics after edits

After a successful mutate, Steiner appends diagnostics for the changed files when a matching server is already running and ready. It never starts a server for this, and it adds nothing when there is nothing to report. Only a limited number of changed files is checked per call; use lsp_diagnostics or a build for the rest.

Troubleshooting

Messages the tools return:

• No language server is configured for .ext: no enabled server lists that extension.
• No language server is enabled: lsp_symbols workspace search has no enabled server.
• Language server <name> failed to start: the executable is missing, crashed, or failed to initialise. Check command, the install, and that root_markers match the project.
• Language server <name> exited unexpectedly: it crashed during a request. The next call restarts it.
• Language server <name> does not support this request: the server does not implement that LSP method.

In the TUI, server stderr is discarded unless session logging is configured; in non-interactive runs it goes to stderr. Rename and other LSP features not listed above are not available.