juvenal 0.2.2

Who guards the agents? A framework for orchestrating AI coding agents through verified implementation phases.

Juvenal

Quis custodiet ipsos custodes? — Who guards the agents?

Juvenal is a framework for orchestrating AI coding agents through verified implementation phases. It prevents agents from cheating on success criteria by separating implementation from verification.

How It Works

A non-agentic Python script orchestrates AI coding agents (Claude or Codex) through alternating steps:

1. Implementation — an agent executes a prompt to build/modify code
2. Verification — separate checkers (scripts, agents, or both) verify the work
3. Retry — if verification fails, the failure context is injected and the agent tries again

The implementing agent and the checking agent are separate processes, so the implementer can't cheat by weakening tests.

Install

pip install -e ".[dev]"

Quick Start

# Scaffold a workflow
juvenal init my-project

# Run a workflow
juvenal run workflow.yaml

# Generate a workflow from a goal
juvenal plan "implement a REST API with tests" -o workflow.yaml

# Plan and immediately run
juvenal do "add authentication to the Flask app"

Workflow Formats

YAML

name: "my-workflow"
backend: claude
max_retries: 999

phases:
  - id: implement
    prompt: "Implement the feature."
    checkers:
      - type: script
        run: "pytest tests/ -x"
      - type: agent
        role: tester

Directory Convention

my-workflow/
  phases/
    01-setup/
      prompt.md            # implementation prompt
      check-build.sh       # script checker (exit 0 = pass)
      check-quality.md     # agent checker
    02-implement/
      prompt.md
      check-tests.sh       # paired with .md = composite
      check-tests.md       # gets {script_output} injected

Bare Markdown

phases/
  01-setup.md              # single phase, default tester checker

Checker Types

Type	Description
script	Shell command; exit 0 = PASS, nonzero = FAIL
agent	AI agent that emits VERDICT: PASS or VERDICT: FAIL: reason
composite	Script runs first, output fed to agent via {script_output}

Built-in Roles

Agent checkers can use built-in verification personas:

• tester — runs tests, checks for build errors
• architect — validates design, checks for circular dependencies
• pm — confirms requirements are met, no TODOs remain
• senior-tester — checks test integrity, looks for cheating
• senior-engineer — reviews code quality, completeness, security

CLI

juvenal run <workflow> [--resume] [--phase X] [--max-retries N] [--backend claude|codex] [--dry-run]
juvenal plan "goal" [-o output.yaml] [--backend claude|codex]
juvenal do "goal" [--backend claude|codex] [--max-retries N]
juvenal status [--state-file path]
juvenal init [directory] [--template name]

License

MIT