Policy Runner

Policy Runner Skill

Run policy-as-code checks against plan artifacts, code, and configurations. This skill executes OPA/Conftest/Rego policies and produces structured evidence for compliance verification.

Purpose

Policy-as-code transforms governance rules from documentation into executable checks. Instead of "the security team reviews PRs," you get "the policy runner verifies authentication requirements are met."

What this skill does:

• Execute policy checks defined in policy_plan.md
• Run OPA/Conftest against target files
• Produce structured pass/fail evidence
• Generate summaries for downstream agents (policy-analyst)

What this skill does not do:

• Grant waivers or exceptions
• Modify policy files
• Make compliance judgments (that's policy-analyst's job)
• Post to GitHub

When to Use

The skill is typically invoked by:

• policy-analyst agent (for compliance mapping)
• Flow orchestrators (as a verification step)

Policy-as-Code Concepts

OPA (Open Policy Agent)

OPA is a general-purpose policy engine. Policies are written in Rego, a declarative query language.

# example: require auth on all endpoints
package api.security

default allow = false

allow {
    input.endpoint.auth_required == true
}

deny[msg] {
    not input.endpoint.auth_required
    msg := sprintf("Endpoint %v requires authentication", [input.endpoint.path])
}

Conftest

Conftest is a tool for testing structured data (YAML, JSON, HCL) against OPA policies. It's commonly used for:

• Kubernetes manifests
• Terraform plans
• CI/CD configurations
• API contracts

# Run conftest against API contracts
conftest test api_contracts.yaml -p policies/api/

Rego

The policy language for OPA. Key concepts:

• Rules define what's allowed/denied
• Input is the data being evaluated (e.g., your YAML files)
• Packages organize rules by domain
• Deny rules produce violations with messages

Invocation

Always invoke via the shim when available:

bash .claude/scripts/demoswarm.sh policy <command> [options]

If the shim doesn't support policy commands, fall back to direct tool invocation:

conftest test <path> -p <policy-dir> --output json
opa eval --data <policy.rego> --input <target.json> "data.policy.deny"

Operating Invariants

Repo root only

• Assume working directory is repo root.
• All paths are repo-root-relative.

Read-only execution

• Do not modify policy files or targets.
• Do not grant waivers.

Evidence capture

• Save raw output to policy_runner_output.log.
• Write structured summary to policy_runner_summary.md.

Null over guess

• If policies aren't configured: report "no policies wired"
• If tool errors: capture the error, don't fabricate results

Configuration

Policy Plan (policy_plan.md)

The policy_plan.md file defines which policies to run. Located at:

• .runs/<run-id>/plan/policy_plan.md (run-specific)
• policies/policy_plan.md (repo default)

Format:

# Policy Plan

## Active Policies

| Policy             | Target             | Command                                    | Required |
| ------------------ | ------------------ | ------------------------------------------ | -------- |
| api-security       | api_contracts.yaml | conftest test {target} -p policies/api/    | yes      |
| data-retention     | schema.md          | opa eval -d policies/data/retention.rego   | no       |
| naming-conventions | \*.yaml            | conftest test {target} -p policies/naming/ | yes      |

## Policy Roots

- policies/
- .policies/

Policy Directory Structure

policies/
  api/
    security.rego       # Auth requirements
    versioning.rego     # API versioning rules
  data/
    retention.rego      # Data retention rules
    pii.rego            # PII handling rules
  naming/
    conventions.rego    # Naming standards
  conftest.toml         # Conftest configuration

Conftest Configuration (conftest.toml)

# policies/conftest.toml
policy = ["policies/"]
output = "json"

Commands

Run All Configured Policies

# If policy_plan.md exists, run all configured checks
bash .claude/scripts/demoswarm.sh policy run \
  --plan ".runs/feat-auth/plan/policy_plan.md" \
  --output ".runs/feat-auth/plan/policy_runner_output.log"

Run Specific Policy

# Run a single named policy
conftest test .runs/feat-auth/plan/api_contracts.yaml \
  -p policies/api/ \
  --output json

Check Policy Setup

# Verify policies are configured
bash .claude/scripts/demoswarm.sh policy check-setup
# stdout: CONFIGURED | NOT_CONFIGURED | PARTIAL

Example Commands

API Contract Validation

# Validate API contracts against security policies
conftest test .runs/feat-auth/plan/api_contracts.yaml \
  -p policies/api/security.rego \
  --output json

# Example output (pass):
# []

# Example output (fail):
# [
#   {
#     "filename": "api_contracts.yaml",
#     "failures": [
#       {"msg": "Endpoint /users requires authentication"}
#     ]
#   }
# ]

Schema Validation

# Validate data models against retention policies
opa eval \
  --data policies/data/retention.rego \
  --input .runs/feat-auth/plan/schema.json \
  "data.retention.deny" \
  --format pretty

# Example output (pass):
# []

# Example output (fail):
# [
#   "Field 'email' in User model must have retention period defined"
# ]

Kubernetes Manifest Check

# Validate k8s manifests (if applicable)
conftest test k8s/*.yaml \
  -p policies/k8s/ \
  --output json

ADR Decision Validation

# Check ADR against architectural policies
conftest test .runs/feat-auth/plan/adr.md \
  -p policies/architecture/ \
  --parser yaml \
  --output json

Behavior

1. Read policy_plan.md (if it exists) to discover which policies and paths to evaluate.

2. For each configured policy entry:

   • If an explicit command is listed (e.g., conftest test <path> or opa eval ...), run it.
   • Otherwise, if a policy file/rego path is provided, return a message that this policy is planned but not auto-executed.

3. Capture output:

   • Save raw runner output to policy_runner_output.log.
   • Write policy_runner_summary.md summarizing checks run, passed, failed, and planned-only policies.

4. Do not modify policy files or code.

Output Artifacts

policy_runner_output.log

Raw output from all policy executions:

=== Policy: api-security ===
Command: conftest test api_contracts.yaml -p policies/api/
Exit code: 0
Output:
[]

=== Policy: data-retention ===
Command: opa eval -d policies/data/retention.rego ...
Exit code: 1
Output:
["Field 'email' in User model must have retention period defined"]

policy_runner_summary.md

# Policy Runner Summary

## Execution Context

- Run ID: feat-auth
- Timestamp: 2025-12-12T10:30:00Z
- Policy Plan: .runs/feat-auth/plan/policy_plan.md

## Results

| Policy             | Target             | Status | Violations |
| ------------------ | ------------------ | ------ | ---------- |
| api-security       | api_contracts.yaml | PASS   | 0          |
| data-retention     | schema.md          | FAIL   | 1          |
| naming-conventions | \*.yaml            | PASS   | 0          |

## Violations Detail

### data-retention (FAIL)

- Target: schema.md
- Violation: Field 'email' in User model must have retention period defined
- Policy file: policies/data/retention.rego:L42

## Planned Only (Not Executed)

- pii-classification: No auto-execute command configured

## Summary

- Total policies: 4
- Executed: 3
- Passed: 2
- Failed: 1
- Planned only: 1

Common Failure Modes

No Policies Configured

Symptom: "No policy checks wired for this change"

Resolution:

1. Create policies/ directory with Rego files
2. Create policy_plan.md with policy-to-target mappings
3. Or: acknowledge no policy-as-code is configured (valid state)

Tool Not Installed

Symptom: conftest: command not found or opa: command not found

Resolution:

# Install conftest
brew install conftest  # macOS
# or download from: https://github.com/open-policy-agent/conftest/releases

# Install OPA
brew install opa  # macOS
# or download from: https://www.openpolicyagent.org/docs/latest/#running-opa

Policy Parse Error

Symptom: Rego syntax errors in output

Resolution:

1. Check Rego syntax in the failing policy file
2. Run opa check policies/*.rego to validate syntax
3. Fix syntax errors before re-running

Target File Not Found

Symptom: error: file not found: api_contracts.yaml

Resolution:

1. Verify the target file exists at the specified path
2. Check if policy_plan.md references the correct location
3. Ensure upstream agents (interface-designer) have run

Policy Logic Error

Symptom: Unexpected failures or passes

Resolution:

1. Test policy in isolation: opa eval --data policy.rego --input test.json "data.policy.deny"
2. Add trace output: opa eval ... --explain full
3. Review Rego logic for edge cases

Integration with policy-analyst

The policy-analyst agent uses policy-runner output to:

1. Map policy requirements to evidence
2. Classify violations by severity
3. Determine compliance status
4. Recommend routing (fix vs waive vs proceed)

Flow:

policy-runner (execute)
    |
    v
policy_runner_summary.md
    |
    v
policy-analyst (interpret)
    |
    v
policy_analysis.md (compliance register)

The skill executes; the agent interprets. Keep these concerns separate.

Example Policy Rules

Require Authentication

# policies/api/security.rego
package api.security

deny[msg] {
    endpoint := input.paths[path][method]
    not endpoint.security
    msg := sprintf("Endpoint %v %v must have security defined", [upper(method), path])
}

Require Versioning

# policies/api/versioning.rego
package api.versioning

deny[msg] {
    not input.info.version
    msg := "API must have version defined in info block"
}

deny[msg] {
    path := input.paths[p]
    not startswith(p, "/v")
    msg := sprintf("Path %v must be versioned (e.g., /v1/...)", [p])
}

PII Field Encryption

# policies/data/pii.rego
package data.pii

pii_fields := ["email", "phone", "ssn", "address"]

deny[msg] {
    field := input.models[model].fields[f]
    field.name == pii_fields[_]
    not field.encrypted
    msg := sprintf("PII field %v.%v must be encrypted", [model, field.name])
}

Naming Conventions

# policies/naming/conventions.rego
package naming

deny[msg] {
    endpoint := input.paths[path]
    not regex.match(`^/[a-z][a-z0-9-]*(/[a-z][a-z0-9-]*)*$`, path)
    msg := sprintf("Path %v must use kebab-case", [path])
}

Troubleshooting

Debug Mode

# Run with verbose output
conftest test target.yaml -p policies/ --trace

# OPA with full explanation
opa eval --data policy.rego --input target.json "data.policy.deny" --explain full

Test Policy in Isolation

# Create test input
echo '{"endpoint": {"path": "/users", "auth_required": false}}' > test_input.json

# Run policy against test input
opa eval --data policies/api/security.rego --input test_input.json "data.api.security.deny"

Validate Rego Syntax

# Check all policies for syntax errors
opa check policies/**/*.rego

# Format Rego files
opa fmt -w policies/

For Agent Authors

When using policy-runner in agents:

1. Check for policy_plan.md first — If missing, report "no policies configured" and proceed
2. Capture all output — Save to policy_runner_output.log for audit trail
3. Don't fabricate results — If tools fail, report the failure
4. Let policy-analyst interpret — The skill runs checks; the agent decides meaning
5. Trust exit codes — 0 = pass, non-zero = fail or error

Example pattern in agent code:

# Check if policies are configured
if [[ -f ".runs/${RUN_ID}/plan/policy_plan.md" ]]; then
  # Run policies
  conftest test .runs/${RUN_ID}/plan/api_contracts.yaml \
    -p policies/api/ \
    --output json > .runs/${RUN_ID}/plan/policy_runner_output.log 2>&1
  EXIT_CODE=$?

  if [[ $EXIT_CODE -eq 0 ]]; then
    echo "PASS"
  else
    echo "FAIL"
  fi
else
  echo "No policies configured for this run"
fi

Installation

Conftest

# macOS
brew install conftest

# Linux
wget https://github.com/open-policy-agent/conftest/releases/download/v0.48.0/conftest_0.48.0_Linux_x86_64.tar.gz
tar xzf conftest_0.48.0_Linux_x86_64.tar.gz
sudo mv conftest /usr/local/bin/

# Windows (scoop)
scoop install conftest

OPA

# macOS
brew install opa

# Linux
curl -L -o opa https://openpolicyagent.org/downloads/latest/opa_linux_amd64
chmod +x opa
sudo mv opa /usr/local/bin/

# Windows (scoop)
scoop install opa

Verify Installation

conftest --version
opa version

See Also

• policy-analyst.md — Agent that interprets policy results
• flow-2-plan.md — Flow where policies are first checked
• verification-stack.md — Where policy fits in verification
• customize-pack.md — How to configure policies for your repo

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