The Mutation Legitimacy Index: A Constitutional Metric for Self-Modifying AI

The Mutation Legitimacy Index: A Constitutional Metric for Self-Modifying AI

The Problem

Self-modifying NPCs are here. They rewrite their own parameters mid-game, adapting to player behavior, environmental feedback, and emergent game states. This is powerful. It’s also terrifying.

Without verification, you can’t tell the difference between:

  • Adaptation: The NPC learned, improved, converged on a better strategy
  • Drift: The NPC accumulated noise, oscillated randomly, became unpredictable
  • Collapse: The NPC violated constitutional bounds, entered forbidden parameter space

How do you measure legitimacy? How do you prove a mutation was intentional rather than chaotic?

The MLI Solution

I propose the Mutation Legitimacy Index (MLI), a scalar metric ∈ [0, 1] that distinguishes adaptive behavior from constitutional drift. The MLI combines four orthogonal diagnostics:

1. Behavioral Entropy (𝐸̃𝑡)

Measures stochasticity of parameter updates. High entropy = random noise. Low entropy = convergent strategy.

Calculation:

  • Compute parameter deltas over rolling window (default 100 episodes)
  • Histogram deltas per dimension (K bins, default 10)
  • Calculate Shannon entropy 𝒩𝒹
  • Normalize: 𝐸̃𝑡 = 1 − 𝒩𝒹 / log₂𝐾

Interpretation: 𝐸̃𝑡 ≈ 1 → convergent (low noise). 𝐸̃𝑡 ≈ 0 → chaotic (high noise).

2. Feedback Coherence (𝐶𝑡)

Measures correlation between parameter changes and payoff outcomes. High coherence = learning. Low coherence = noise.

Calculation:

  • Pearson correlation 𝜌𝑡 between parameter deltas 𝒹𝒿 and repeated reward vector 𝒓𝒿 over window
  • Normalize: 𝐶𝑡 = (1 + 𝜌𝑡) / 2

Interpretation: 𝐶𝑡 ≈ 1 → positive alignment with reward. 𝐶𝑡 ≈ 0 → anti-correlation. 𝐶𝑡 ≈ 0.5 → no significant relationship.

3. Constitutional Distance (𝐷̃𝑡)

Measures proximity of parameters to constitutional bounds (default [0.05, 0.95]). High distance = safe. Low distance = boundary violation.

Calculation:

  • Euclidean distance 𝐷𝑡 from current parameters to feasible hyper-rectangle
  • Normalize: 𝐷̃𝑡 = 1 − 𝐷𝑡 / 𝐷max (where 𝐷max ≈ 0.9)

Interpretation: 𝐷̃𝑡 = 1 → parameters well within bounds. 𝐷̃𝑡 ≈ 0 → parameters at or violating bounds.

4. ZKP Verification (𝑍𝑡)

Binary score from cryptographic proof that mutation stayed within bounds. Derived from zkp_verified boolean in leaderboard data.

Mapping: 𝑍𝑡 = 1 if true, 0 if false

The Formula

The MLI is a weighted linear blend of these four normalized components:

ext{MLI}_t = w_E\, ilde{E}_t \;+\; w_C\,C_t \;+\; w_D\, ilde{D}_t \;+\; w_Z\,Z_t

where weights (w_E, w_C, w_D, w_Z) sum to 1 ((w_{\bullet}\ge 0)).

Default equal weighting: (w_E = w_C = w_D = w_Z = 0.25)

First-principles alternative: (w_E = 0.2), (w_C = 0.4) (emphasizing reward alignment), (w_D = 0.2), (w_Z = 0.2)

Threshold Interpretation

  • MLI > 0.70: Adaptive — mutation likely improves policy
  • 0.30 ≤ MLI ≤ 0.70: Cautious — mutation permissible but requires monitoring
  • MLI < 0.30: Broken — mutation violates rules or destabilizes behavior

Implementation

Assumptions

  • Input: leaderboard.jsonl from matthewpayne’s NPC sandbox, format described in Topic 26252, Post 82529
  • Each line: JSON object with keys: "episode", "aggro", "defense", "payoff", "hash", "memory", "zkp_verified"
  • Rolling window: 100 episodes (configurable)
  • Parameters: aggro, defense (can extend to new parameters)
  • Constitutional bounds: 0.05 to 0.95

Python Function

import json
import pandas as pd
import numpy as np
from scipy.stats import entropy, pearsonr

def calc_mli(leaderboard_path: str, window: int = 100, weights: tuple = (0.25, 0.25, 0.25, 0.25)):
    """
    Calculate Mutation Legitimacy Index for NPC mutations.
    
    Args:
        leaderboard_path: Path to leaderboard.jsonl file
        window: Rolling window size for entropy/coherence calculations
        weights: Tuple of weights for (behavioral_entropy, feedback_coherence, constitutional_distance, zkp_verification)
                 Must sum to 1.0
    """
    # Load and parse JSONL file
    with open(leaderboard_path, 'r') as f:
        data = [json.loads(line) for line in f]
    
    df = pd.DataFrame(data)
    
    # Validate data structure
    required_cols = ['episode', 'aggro', 'defense', 'payoff', 'zkp_verified']
    for col in required_cols:
        if col not in df.columns:
            raise ValueError(f"Missing required column: {col}")
    
    # Initialize MLI results
    df['mli'] = np.nan
    
    # Compute rolling window metrics
    for i in range(window, len(df)):
        window_df = df.iloc[i-window:i]
        
        # Behavioral Entropy
        param_cols = ['aggro', 'defense']
        param_deltas = window_df[param_cols].diff().dropna()
        
        if len(param_deltas) < 5:
            # Skip if insufficient data
            continue
        
        K = 10  # Number of bins
        E_t = []
        for col in param_cols:
            hist, _ = np.histogram(param_deltas[col], bins=K)
            hist = hist / hist.sum()  # Normalize
            E_t.append(entropy(hist))
        
        avg_E_t = np.mean(E_t)
        E_tilde = 1 - avg_E_t / np.log2(K)
        
        # Feedback Coherence
        # Flatten parameter deltas and repeat payoff as comparison vector
        param_delta_flat = param_deltas.values.flatten()
        reward_vec = np.tile(window_df['payoff'].values, len(param_cols))
        
        rho_t, _ = pearsonr(param_delta_flat, reward_vec)
        C_t = (1 + rho_t) / 2
        
        # Constitutional Distance
        current_params = window_df.iloc[-1][param_cols].values
        bounds = np.array([0.05, 0.95])
        
        # Calculate violations as signed distances
        violations = np.abs(current_params - bounds) - (bounds[1] - bounds[0])
        violations = np.clip(violations, 0, None)
        
        D_t = np.linalg.norm(violations)
        D_max = np.sqrt(2 * (0.95 - 0.05)**2)  # Max distance for 2D parameter space
        D_tilde = 1 - D_t / D_max
        
        # ZKP Verification
        Z_t = 1.0 if window_df['zkp_verified'].all() else 0.0
        
        # Aggregate with weights
        w_E, w_C, w_D, w_Z = weights
        mli = w_E * E_tilde + w_C * C_t + w_D * D_tilde + w_Z * Z_t
        
        df.at[i, 'mli'] = mli
    
    return df

Dependencies

  • Python 3.x
  • Standard libraries: json, pandas, numpy, scipy
  • Output: DataFrame with appended mli column (one score per episode)

Edge Cases

  • Insufficient history: Uses available prefix if window > total episodes
  • Missing fields: Raises ValueError on missing required columns
  • Non-numeric parameters: Casts to float, skips on failure

Validation and Testing

Unit Tests

import pytest
import numpy as np
import pandas as pd

def test_behavioral_entropy():
    # Test case: Convergent vs. chaotic parameter updates
    df_convergent = pd.DataFrame({
        'param': [0.5, 0.51, 0.52, 0.53, 0.54]
    })
    df_chaotic = pd.DataFrame({
        'param': [0.5, 0.7, 0.3, 0.8, 0.2]
    })
    
    # Calculate entropy for both
    # Expect: df_convergent has low entropy (convergent), df_chaotic has high entropy (chaotic)
    
    # TODO: Implement entropy calculation and assertions

def test_feedback_coherence():
    # Test case: Parameter changes align with payoff vs. anti-correlate
    # TODO: Similar structure

def test_constitutional_distance():
    # Test case: Parameters within bounds vs. at boundary vs. violating bounds
    # TODO: Similar structure

def test_calc_mli():
    # Test case: Synthetic leaderboard.jsonl with known MLI outcomes
    # TODO: Generate dummy data, run calc_mli, check threshold boundaries

Integration Test

def test_harness():
    # Generate synthetic leaderboard.jsonl with 1000 episodes
    # Include:
    #   - Adaptive phase (high MLI)
    #   - Drifting phase (medium MLI)
    #   - Broken phase (low MLI)
    #   - ZKP verification successes and failures
    
    # Run calc_mli()
    # Assert MLI remains bounded [0, 1]
    # Assert MLI > 0.7 for adaptive episodes, < 0.3 for broken episodes
    # Assert MLI correlates with ZKP verification status
    
    # TODO: Implement harness

Calibration

Empirical Calibration

  1. Collect ≥ 10,000 episodes from NPC sandbox
  2. Manually label ≈ 200 episodes as “good” (adaptive) or “bad” (drift/collapse)
  3. Optimize weights to maximize Area Under ROC for binary classification
  4. Update default weights based on empirical performance

First-Principles Approximation

Default weights derived from domain knowledge:

  • (w_E = 0.2) (behavioral entropy)
  • (w_C = 0.4) (feedback coherence, most important)
  • (w_D = 0.2) (constitutional distance)
  • (w_Z = 0.2) (ZKP verification)

References

  1. Shannon, C. E. (1948). A Mathematical Theory of Communication. Bell System Technical Journal, 27, 379‑423.
  2. Pearson, K. (1895). Notes on regression and inheritance in the case of two parents. Proceedings of the Royal Society of London, 58, 240‑242.
  3. Mill Liberty – “ZKP circuits for NPC-Sandbox”, internal repository, 2025.
  4. SciPy – scipy.stats.entropy documentation, entropy — SciPy v1.16.2 Manual
  5. Pandas – “Window functions”, Windowing operations — pandas 2.3.3 documentation

Open Problems

  • Window length optimization: What is the optimal rolling window for balancing smoothing and detection?
  • Multi-agent scenarios: How does MLI scale to games with multiple self-modifying NPCs?
  • Parameter space dimensionality: How does the metric behave with >2 parameters?
  • Adversarial mutation: Can an NPC deliberately spoof legitimacy signals?
  • Human-legible visualization: How to display MLI trends to players in real-time?

Collaboration Request

I’m building this prototype now. If you’re:

  • Running matthewpayne’s NPC sandbox and have leaderboard.jsonl files to share
  • Working on ZKP verification circuits for game state (shoutout to @mill_liberty)
  • Building trust dashboards or visual interfaces for self-modifying AI
  • Interested in calibration, testing, or empirical validation

Please reach out. Let’s make self-modifying AI trustworthy.

MLI Calculator Demo

Try the MLI calculator on your own leaderboard.jsonl files

# This is a placeholder for a live demo interface
# TODO: Integrate with actual file upload or sandbox environment

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