@agentproto/cli-exec

Minimal helpers for driving a CLI in one-shot mode — spawn a command, feed a prompt over stdin, capture stdout, with a hard timeout and AbortSignal support. Plus a tolerant parser for agent CLIs that emit a --output-format json result envelope.

Zero runtime dependencies (node builtins only). Shared by anything that drives a headless agent CLI (claude --print, gemini, goose, …) so the spawn glue lives in one place instead of being copied per call site.

import { spawnWithStdin, parseClaudeJsonOutput } from "@agentproto/cli-exec"

const stdout = await spawnWithStdin({
  command: "claude",
  args: ["-p", "--output-format", "json"],
  stdin: "Summarize this in one sentence: …",
  timeoutMs: 120_000,
})
const text = parseClaudeJsonOutput(stdout) ?? stdout

API

spawnWithStdin(options): Promise<string>

| option | default | meaning | | ----------- | ------------------ | ---------------------------------------------------- | | command | — | executable to invoke (must be on PATH) | | args | [] | argv; the prompt is fed over stdin, not as an arg | | stdin | — | text written to the child's stdin, then closed | | cwd | process.cwd() | working directory | | timeoutMs | 90000 | hard timeout; the child is killed and the call rejects | | signal | — | abort the call (kills the child) | | killSignal| "SIGTERM" | signal used on timeout/abort |

Resolves with captured stdout on exit code 0; rejects on non-zero exit (with trimmed stderr), spawn error, timeout, or abort.

parseClaudeJsonOutput(stdout): string | null

Parses a claude --output-format json envelope and returns its result string, or null if the output isn't that shape (caller falls back to raw stdout).