Your first rule pack¶

Create a deterministic check, package it, then add a review for your coding agent.

Create a deterministic rule¶

Require an AGENTS.md at the repository root:

from pathlib import Path

from ryni.models import Finding, Rule, RuleScope


def check_instructions(root: Path) -> list[Finding]:
    path = root / "AGENTS.md"
    if path.is_file():
        return []
    return [Finding(str(path), 1, "TEAM001", "Add an AGENTS.md at the repository root.")]


RULE = Rule(
    id="TEAM001",
    name="require-agent-instructions",
    description="Every repository must have a root AGENTS.md.",
    filename="",
    scope=RuleScope.REPOSITORY,
    evaluate=check_instructions,
)

The function receives the repository root and returns findings—or an empty list when the check passes. The Rule gives the check an identity and tells Rýni when to run it.

Put it in a rule pack¶

A rule pack is a Python package. Save the rule above in require_instructions.py:

team-rules/
├── pyproject.toml
└── src/
    └── team_rules/
        ├── __init__.py
        └── require_instructions.py   # The rule above

Bundle it in src/team_rules/__init__.py:

from ryni.models import RulePack

from .require_instructions import RULE

PACK = RulePack(
    name="team-rules",
    description="Our team's agent harness conventions.",
    rules=(RULE,),
)

Register the pack in pyproject.toml so Rýni discovers it when installed:

[build-system]
requires = ["hatchling"]
build-backend = "hatchling.build"

[project]
name = "team-rules"
version = "0.1.0"
requires-python = ">=3.14"
dependencies = ["ryni>=0.1.1"]

[project.entry-points."ryni.rules"]
team = "team_rules:PACK"

[tool.hatch.build.targets.wheel]
packages = ["src/team_rules"]

Install and run¶

From the repository you want to check, add Rýni and your rule pack as development dependencies. Here, ../team-rules points to the pack you just created:

uv add --dev ryni ../team-rules
uv run ryni check .

Installed rules are active automatically. If the repository has no AGENTS.md, your rule reports:

AGENTS.md:1: TEAM001 Add an AGENTS.md at the repository root.

Add the file and rerun the check. Commit pyproject.toml and uv.lock to record the team's dependencies; anyone installing them will also need access to the pack.

Create a non-deterministic rule¶

Check AGENTS.md for contradictory instructions with a ReviewRule. Save this as src/team_rules/contradictions.py:

from ryni.models import ReviewRule

RULE = ReviewRule(
    id="TEAM002",
    name="no-contradictory-instructions",
    description="AGENTS.md must not contain contradictory instructions.",
    instructions="""
Find contradictory instructions in the root AGENTS.md.
Cite both sides of each conflict, accounting for scope and exceptions.
""",
)

Add it alongside the deterministic rule in src/team_rules/__init__.py:

from ryni.models import RulePack

from .require_instructions import RULE as REQUIRE_INSTRUCTIONS
from .contradictions import RULE as CONTRADICTIONS

PACK = RulePack(
    name="team-rules",
    description="Our team's agent harness conventions.",
    rules=(REQUIRE_INSTRUCTIONS, CONTRADICTIONS),
)

Run with your agent¶

ryni check prepares reviews; your agent completes them with the ryni-check skill. From the repository you want to check, refresh the pack and install the skill:

Claude CodeCodex

uv add --dev --editable ../team-rules
uv run ryni skill install .claude/skills

Open Claude Code in this repository and send:

/ryni-check

uv add --dev --editable ../team-rules
uv run ryni skill install .agents/skills

Open Codex in this repository and send:

$ryni-check

The skill runs deterministic checks, delegates reviews to sub-agents, and reports the combined findings. Your agent must support sub-agents to complete reviews.