LSP Diagnostics

The /lsp <file> command pulls the real diagnostics for a code file — the same errors and warnings your editor would show — by starting the appropriate language server and speaking the Language Server Protocol with it.

It’s a manual, per-file command: you pass a file, ChatCLI starts the language server for its language, opens the document, waits for diagnostics and prints them. There is no automatic injection into /agent//coder.

How it works

/lsp ./cli/agent_mode.go
     │
     ▼
detect language by extension (.go → gopls)
     │
     ▼
start the language server (stdio, JSON-RPC with Content-Length framing)
     │
     ▼
initialize → didOpen(file) → wait for publishDiagnostics (up to 12s)
     │
     ▼
print errors/warnings (or "No problems found")

Language detection — by file extension.
Spawn — starts the language’s server (default command or your override). If the binary isn’t installed/on PATH, /lsp says so.
Handshake — initialize + textDocument/didOpen.
Diagnostics — waits up to 12s for textDocument/publishDiagnostics and renders the result.

Languages and default commands

Each language uses a conventional stdio command, overridable via an environment variable. The binary must be installed and on PATH.

Extensions	Language server (default)	Override
`.go`	`gopls`	`CHATCLI_LSP_GO_CMD`
`.py`	`pyright-langserver --stdio`	`CHATCLI_LSP_PYTHON_CMD`
`.ts` `.tsx` `.js` `.jsx`	`typescript-language-server --stdio`	`CHATCLI_LSP_TS_CMD`
`.rs`	`rust-analyzer`	`CHATCLI_LSP_RUST_CMD`
`.c` `.h`	`clangd`	`CHATCLI_LSP_C_CMD`
`.cpp` `.cc`	`clangd`	`CHATCLI_LSP_CPP_CMD`
`.java`	`jdtls`	`CHATCLI_LSP_JAVA_CMD`
`.rb`	`solargraph stdio`	`CHATCLI_LSP_RUBY_CMD`

# Example: enable gopls trace or point at a different binary
export CHATCLI_LSP_GO_CMD="gopls -rpc.trace"
export CHATCLI_LSP_PYTHON_CMD="pyright-langserver --stdio"

Usage

> /lsp ./cli/agent_mode.go
  Starting language server: gopls...

  Diagnostics for agent_mode.go
  ─────────────────────────────────────────
  No problems found.

> /lsp ./broken.go
  Starting language server: gopls...

  Diagnostics for broken.go
  ─────────────────────────────────────────
  error  12:6   undefined: fmt.Printline
  warn   30:2   declared and not used: x

Pair it with /coder: run /lsp on a file you just edited to confirm you didn’t introduce compile errors before moving on.

The same LSP engine is also available to the model in agent and coder modes as the @lsp builtin tool — backed by a session-scoped server pool (the server initializes once per project and is reused across calls; idle servers shut down after 5 minutes):

Subcommand	What it does
`diagnostics {file}`	compiler errors/warnings without running a build
`definition {file, line, column}`	where the symbol is defined
`references {file, line, column, limit?}`	every usage of the symbol across the project
`symbols {file}`	file outline: functions, types, methods
`hover {file, line, column}`	the symbol’s signature/type/docs

Positions are 1-based both ways. Where @search finds text, @lsp understands code: after editing a file, diagnostics confirms it still compiles; before changing a symbol, references shows the blast radius.

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LSP Diagnostics

How it works

Languages and default commands

Usage

The @lsp tool — semantic navigation for the agent

See also

​How it works

​Languages and default commands

​Usage

​The @lsp tool — semantic navigation for the agent

​See also

How it works

Languages and default commands

Usage

The @lsp tool — semantic navigation for the agent

See also