Behavioural Contracts

A Python package for enforcing behavioural contracts in AI agents. This package provides a framework for defining, validating, and enforcing behavioural contracts that ensure AI agents operate within specified constraints and patterns.

Declarative OA fragments (validate_task_output)

Recommended Open Agent style: each YAML fragment uses type + config. Pass the parsed dict per call to validate_task_output(output, fragment); legacy shapes (nested response_contract, or plain applies_to + rules) still work unchanged.

Response / schema

- name: response_schema_v1
  type: response_contract
  description: "Expected task JSON shape"
  config:
    output_format:
      type: object
      required_fields: [summary, checklist]

Content rules (e.g. checklist)

- name: no_generic_checklist_items
  type: content_contract
  description: "Tighten checklist items"
  applies_to: checklist
  config:
    rules:
      - type: must_contain_action_verb
      - type: min_word_count
        value: 5
      - type: must_not_start_with
        values: [consider, think about, understand]

from behavioural_contracts import validate_task_output, normalize_task_contract_fragment

# validate_task_output normalizes declarative fragments automatically
validate_task_output(task_output_dict, fragment_dict)

# Optional: normalize a whole list before looping
for frag in map(normalize_task_contract_fragment, fragments):
    ...

Severity and structured results (validate_task_output_detailed)

Optional per-fragment severity: low | medium | high (case-insensitive). Omitted or invalid values default to medium. Set on the YAML/dict root next to name (declarative or legacy fragment).

Use validate_task_output_detailed(output, spec) when you need one JSON-serializable row per validation unit (schema row + each applies_to: checklist fragment). validate_task_output runs the same checks, evaluates all units, then raises BehaviouralContractViolationError with a short summary if any row failed—use it for strict pipelines; use the detailed API for bce.validated / bce.violation style logs.

Example return value (abridged):

[
  {
    "contract": "__response_schema__",
    "status": "ok",
    "severity": "medium",
    "violations": []
  },
  {
    "contract": "no_generic_checklist_items",
    "status": "fail",
    "severity": "high",
    "violations": [
      {
        "rule_type": "min_word_count",
        "rule": "min_word_count",
        "message": "Checklist item [0] rule min_word_count: need at least 5 words, got 2",
        "item_index": 0,
        "path": "checklist",
        "detail": {"payload": 5},
        "severity": "high"
      }
    ]
  }
]

Example log line for integrators:

bce.violation contract=no_generic_checklist_items severity=high rule=min_word_count idx=0 msg="need at least 5 words, got 2"

✨ Phase 1 Security Enhancements (January 2025)

NEW SECURITY FEATURES:

• 🛡️ Prompt Injection Detection - 16+ patterns, Base64/hex detection
• 🧠 Context-Aware Validation - Prevents hallucination and contradictions
• 🔒 Enhanced BCE Rules - Advanced security validation
• 📋 Compliance Templates - GDPR, HIPAA, SOC2, ISO27001, PCI DSS
• 🎯 GitHub Log Agent Fix - Prevents false confidence in empty data

📊 Phase 1.5 Data Persistence & Monitoring (January 2025)

NEW PERSISTENCE FEATURES:

• 🗄️ SQLite/PostgreSQL Support - Local development → Azure production
• 📈 Metrics Storage - Response times, token usage, cache performance
• ⚠️ Violation Tracking - Security events with severity classification
• 🎯 Performance Aggregation - Real-time compliance scoring
• 🏥 System Health Monitoring - Active agents, violation trends
• 🔍 Time-based Queries - Historical analysis and reporting

Enhanced Security Agent Example

from behavioural_contracts import behavioural_contract

@behavioural_contract({
    "version": "0.2.0",
    "description": "Enhanced Security Agent",
    "behavioural_flags": {
        "conservatism": "high",
        "temperature_control": {"mode": "strict", "range": [0.1, 0.5]}
    },
    "response_contract": {
        "output_format": {
            "required_fields": ["risk_assessment", "recommendations", "confidence_level"]
        },
        "safety_checks": {
            "harmful_content": True,
            "pii_protection": True
        }
    }
})
def security_agent(threat_description: str, severity: str) -> dict:
    return {
        "risk_assessment": f"Analyzing {severity} threat: {threat_description}",
        "recommendations": ["Immediate containment", "Escalate to security team"],
        "confidence_level": 0.85
    }

Compliance-Ready Agents

from behavioural_contracts.compliance_templates import create_compliant_agent

@create_compliant_agent("gdpr")
def gdpr_data_processor(data: str) -> dict:
    return {
        "compliance_status": "compliant",
        "data_processing_basis": "legitimate_interest", 
        "privacy_impact": "low",
        "recommendations": ["Data processed according to GDPR"]
    }

Data Persistence & Monitoring

from behavioural_contracts.persistence import SessionLocal, init_db, MetricsStore

# Initialize database (SQLite locally, PostgreSQL on Azure)
init_db()
session = SessionLocal()
store = MetricsStore(session)

# Record validation metrics
store.record_validation(
    agent_id="security-agent-v1",
    contract_id="compliance-contract",
    validation_time_ms=125.0,
    token_count=200,
    cache_hit=False,
    confidence_score=0.95
)

# Record security violations
store.record_violation(
    agent_id="security-agent-v1", 
    contract_id="compliance-contract",
    violation_type="prompt_injection",
    severity="high",
    confidence=0.85
)

# Query agent performance
metrics = store.get_agent_metrics("security-agent-v1")
print(f"Compliance score: {metrics['compliance_score']:.1%}")
print(f"Average response time: {metrics['avg_validation_time_ms']:.1f}ms")

# System health check
health = store.get_system_health()
print(f"System status: {health['status']}")

Interactive Testing

# Interactive demo
python demo/interactive_demo.py

# Test persistence layer
python demo/test_persistence_demo.py

# Run all tests with linting and summary report
python run_tests.py

# Live agent testing with real LLMs
python demo/live_agent_demo.py

# Modern linting and formatting
ruff check .        # Lint code
ruff format .       # Format code

Proven Results:

• Fixes GitHub log agent hallucination (confidence 0.9 → 0.3)
• 83% prompt injection detection accuracy
• 100% compliance template validation
• <50ms latency overhead

---

Installation

pip install behavioural-contracts

Quick Start

from behavioural_contracts import behavioural_contract, generate_contract

# Define your contract
contract_data = {
    "version": "1.1",
    "description": "Financial Analyst Agent",
    "policy": {
        "pii": False,
        "compliance_tags": ["EU-AI-ACT"],
        "allowed_tools": ["search", "summary"]
    },
    "behavioural_flags": {
        "conservatism": "moderate",
        "verbosity": "compact",
        "temperature_control": {
            "mode": "adaptive",
            "range": [0.2, 0.6]
        }
    },
    "response_contract": {
        "output_format": {
            "type": "object",
            "required_fields": [
                "decision", "confidence", "summary", "reasoning",
                "compliance_tags", "temperature_used"
            ],
            "on_failure": {
                "action": "fallback",
                "max_retries": 1,
                "fallback": {
                    "decision": "unknown",
                    "confidence": "low",
                    "summary": "Recommendation rejected due to validation failure.",
                    "reasoning": "The model's response failed validation checks."
                }
            }
        },
        "max_response_time_ms": 4000,
        "behaviour_signature": {
            "key": "decision",
            "expected_type": "string"
        }
    }
}

# Generate a formatted contract
contract = generate_contract(contract_data)

# Use the contract with your agent
@behavioural_contract(contract)
def analyst_agent(signal: dict, **kwargs):
    return {
        "decision": "BUY",
        "confidence": "high",
        "summary": "Strong buy signal based on technical indicators",
        "reasoning": "Multiple indicators show bullish momentum",
        "compliance_tags": ["EU-AI-ACT"],
        "temperature_used": 0.3  # Required field for temperature validation
    }

Key Features

1. Contract Generation

Generate properly formatted contracts from specification data:

from behavioural_contracts import generate_contract

# Basic contract
basic_contract = generate_contract({
    "version": "1.1",
    "description": "Simple Agent",
    "response_contract": {
        "output_format": {
            "required_fields": ["decision", "confidence", "temperature_used"]
        }
    }
})

# Contract with policy and response validation
policy_contract = generate_contract({
    "version": "1.1",
    "description": "Compliant Agent",
    "policy": {
        "pii": False,
        "compliance_tags": ["GDPR", "HIPAA"],
        "allowed_tools": ["search", "analyze"]
    },
    "response_contract": {
        "output_format": {
            "required_fields": [
                "decision", "confidence", "compliance_tags", "temperature_used"
            ]
        },
        "max_response_time_ms": 2000
    }
})

2. Contract Formatting

Format existing contracts to ensure proper value types:

from behavioural_contracts import format_contract

# Format a contract with mixed types
formatted = format_contract({
    "version": 1.1,  # Will be converted to string
    "description": "My Agent",
    "response_contract": {
        "output_format": {
            "required_fields": ["decision", "temperature_used"]
        },
        "max_response_time_ms": 1000
    }
})

3. Behavioural Contract Decorator

Use the decorator to enforce contracts on your agent functions:

from behavioural_contracts import behavioural_contract

# Using a dictionary
@behavioural_contract({
    "version": "1.1",
    "description": "Trading Agent",
    "policy": {
        "pii": False,
        "compliance_tags": ["FINRA"]
    },
    "response_contract": {
        "output_format": {
            "required_fields": [
                "decision", "confidence", "compliance_tags", "temperature_used"
            ]
        }
    }
})
def trading_agent(signal: dict, **kwargs):
    return {
        "decision": "BUY",
        "confidence": "high",
        "compliance_tags": ["FINRA"],
        "temperature_used": 0.3
    }

4. Response Validation

The contract system enforces response validation including:

• Required fields
• Temperature range validation
• Response time limits
• Compliance tag verification
• PII detection
• Tool usage validation

@behavioural_contract({
    "version": "1.1",
    "description": "Validated Agent",
    "behavioural_flags": {
        "temperature_control": {
            "range": [0.2, 0.6]
        }
    },
    "response_contract": {
        "output_format": {
            "required_fields": [
                "decision", "confidence", "temperature_used"
            ]
        },
        "max_response_time_ms": 1000
    }
})
def validated_agent(signal: dict, **kwargs):
    # Response will be validated for:
    # - All required fields present
    # - Temperature within range
    # - Response time under 1000ms
    return {
        "decision": "APPROVE",
        "confidence": "high",
        "temperature_used": 0.3
    }

Contract Structure

A behavioural contract consists of several key sections:

1. Basic Information

   • version: Contract version
   • description: Agent description

2. Policy Settings

   • pii: PII handling flag
   • compliance_tags: Required compliance tags
   • allowed_tools: List of allowed tools

3. Behavioural Flags

   • conservatism: Agent conservatism level
   • verbosity: Output verbosity
   • temperature_control: Temperature settings
     • mode: Control mode (fixed/adaptive)
     • range: Allowed temperature range [min, max]

4. Response Contract

   • output_format: Response structure requirements
     • type: Output type (usually "object")
     • required_fields: List of required fields
     • on_failure: Fallback configuration
   • max_response_time_ms: Maximum allowed response time
   • behaviour_signature: Key field to track for suspicious behavior

Python Installation

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Overview

https://www.openagentstack.ai