First machine

Get Corbie

Corbie is one binary. Download it and put it on your path.

  curl -Lo corbie https://github.com/zummed/corbie/releases/latest/download/corbie-linux-amd64
  chmod +x corbie
  mv corbie ~/.local/bin/

Write and run it

Put these two files in a new directory and run the command.

flow: fetch-title
input: { url: string }

stages:
  get_title:
    job:
      script: ./fetch-title.js
      input: { url: "${input.url}" }
      allow: [net:example.com]

output: ${stages.get_title.output}

const page = http.get(input.url)
const title = html.parse(page.body).find("title").text

return { url: input.url, title }

corbie test title.yaml --input '{"url": "https://example.com"}'  output: {"title":"Example Domain","url":"https://example.com"}  used: net:example.com:443

The definition is a flow with one stage. The stage's job names the script, its input and its allow: list. corbie test runs a machine in one process, with nothing set up. output: is the flow's output, and used: lists each permission the script used.

Remove the permission

Delete the allow: line and run the same command.

flow: fetch-title
input: { url: string }

stages:
  get_title:
    job:
      script: ./fetch-title.js
      input: { url: "${input.url}" }

output: ${stages.get_title.output}

corbie test title.yaml --input '{"url": "https://example.com"}'  refused: net:example.com:443  by: the job "get_title" in the definition of "fetch-title"  fix: add the line net:example.com:443 to the allow list of the job "get_title" in the definition of "fetch-title"

The script called http.get, and Corbie refused the call before a connection was made. The run ended as failed (denied). The three lines give the permission that was missing, the job that lacked it and the line that grants it. Put the allow: line back.

With an AI assistant

An assistant can write both files. Connect it to Corbie once. This command is for Claude Code, and any assistant that uses MCP servers takes the same settings.

  claude mcp add corbie -- corbie mcp --allow test

Then ask. Say "using Corbie", or the assistant writes a program of its own.

  Using Corbie, make me something that fetches https://example.com and tells
  me the title of the page.

The assistant reads this manual through the connection, writes the two files and runs them with corbie test. Read the allow: lists it wrote before you run the machine yourself.

Next: A list runs one job for each item of a list.