Codex, one turn per post: each post in its thread from a user it hears starts codex exec with the run's line and the post on its standard input; it reads what was said before with ocx2 thread, and answers with ocx2 post. create adds the envelope, the clone, process.user and the objective.

{
  "workspace": [
    {
      "step": "directory",
      "at": "$$root$$/$$process_user$$/projects/$$repository_name$$/$$run$$"
    },
    {
      "step": "password"
    },
    {
      "step": "clone",
      "into": "$$workspace$$/clone"
    },
    {
      "step": "checkout",
      "of": "trunk",
      "into": "$$workspace$$/tree"
    }
  ],
  "sandbox": {
    "uid": 1000,
    "gid": 1000,
    "linux_capabilities": [],
    "network": true,
    "isolate_terminal": true,
    "ends_with_parent": true,
    "read_only": [
      "/usr",
      "/bin",
      "/sbin",
      "/lib",
      "/lib64",
      "/etc/resolv.conf",
      "/etc/hosts",
      "/etc/nsswitch.conf",
      "/etc/ssl/certs",
      "$$release$$"
    ],
    "read_write": [
      "$$workspace$$"
    ],
    "homes": [
      "/root/.codex"
    ],
    "created_files": [
      {
        "at": "/etc/passwd",
        "text": "$$process_user$$:x:1000:1000::$$workspace$$:/bin/sh\n"
      }
    ],
    "proc": "/proc",
    "dev": "/dev",
    "tmp": "/tmp"
  },
  "limits": {
    "wall": "8h"
  },
  "process": {
    "command": [
      "/usr/bin/codex",
      "exec",
      "--dangerously-bypass-approvals-and-sandbox",
      "--skip-git-repo-check",
      "Your standard input holds a line {\"run\", \"objective\"}: work toward that objective in this checkout. When a second line {\"post\", \"from\", \"text\"} follows, it is a forum post to you: read what was said before it with `ocx2 thread POST`, then answer it with `ocx2 post POST TEXT`, POST being its hash, from this directory."
    ],
    "cwd": "$$tree$$",
    "session": true,
    "hears": [
      "stone"
    ],
    "deliveries": "start",
    "keep": {
      "stderr": "1K"
    },
    "env": {
      "HOME": "$$workspace$$",
      "USER": "$$process_user$$",
      "PATH": "$$release$$:/usr/local/bin:/usr/bin:/bin"
    }
  }
}