# Session 105 Track 2: Aggregation Strategy Validation

**Date**: 2025-12-29
**Purpose**: Validate that Session 104's coherence aggregation fix (geometric → min-weighted-critical) properly addresses impossible travel scenarios

## Background

Session 103 Track 3 discovered that impossible travel (Portland → Tokyo in 15 min) resulted in CI=0.45, which is too high for a severe security violation.

Session 104 Track 1 identified the root cause: Weighted geometric mean aggregation masks low spatial coherence scores due to fractional exponents (0.1^0.3 ≈ 0.5).

Session 104 implemented **min-weighted-critical aggregation**: Overall CI cannot exceed the minimum of critical dimensions (spatial, capability).

## Track 2 Objective

Rerun Session 103's extended tests with the new aggregation strategy to validate the fix works across all scenarios.

## Test Suite Execution

### 1. Aggregation Strategy Comparison

**Test**: `test_coherence_aggregation_comparison.py`
**Status**: ✅ All 3 tests pass

#### Test 1: Impossible Travel (Portland → Tokyo in 15 min)

```
Scenario: Portland → Tokyo in 15 minutes (impossible!)
Expected: Min-weighted-critical should be SEVERE

Results:
  Geometric Mean:              0.455 (LENIENT - security risk!)
  Min-Weighted-Critical:       0.100 (SEVERE - correct!)
  Security Improvement:        78% reduction in CI
```

**Analysis**:
- Geometric mean gives CI=0.455 despite spatial=0.1 (impossible travel)
- Min-weighted-critical correctly floors CI at spatial coherence (0.1)
- This is a **78% security improvement** (0.455 → 0.100)

#### Test 2: All Coherent (Staying at Portland)

```
Scenario: Remaining at Portland for 1 hour (legitimate)
Expected: Both strategies should give high, similar scores

Results:
  Geometric Mean:              0.908
  Min-Weighted-Critical:       0.840
  Difference:                  0.068 (acceptable)
```

**Analysis**:
- Both strategies give high scores for legitimate behavior
- Difference is small (6.8%) - acceptable tradeoff
- Min-weighted-critical doesn't over-penalize legitimate scenarios

#### Test 3: Legitimate Fast Travel

```
Scenario: Portland → nearby city (150km in 2 hours)
Expected: CI should be moderate (legitimate but fast)

Results:
  Min-Weighted-Critical:       0.833 (moderate, reasonable)
```

**Analysis**:
- CI is floored by lowest critical dimension (spatial)
- Still high enough (0.833) for legitimate fast travel
- Security property maintained without false positives

### 2. Spatial Coherence Tightening

**Test**: `test_spatial_coherence_tightening.py`
**Status**: ✅ All 15 tests pass

#### Key Validations

1. **Geo Distance Calculation** (4 tests)
   - Same location: 0 km ✓
   - Portland → Seattle: ~235 km ✓
   - Portland → Tokyo: ~7800 km ✓
   - Portland → Sydney: ~12000 km ✓

2. **Velocity Profiles** (3 tests)
   - edge-device: 10 km/h (walking) ✓
   - mobile: 100 km/h (car) ✓
   - server: 0 km/h (stationary) ✓

3. **Legitimate Travel** (3 tests)
   - No history: neutral (0.5) ✓
   - Same location: high coherence (≥0.9) ✓
   - Slow movement (60 km/h): high coherence (≥0.7) ✓

4. **Impossible Travel** (4 tests)
   - Teleport to Tokyo: VERY LOW (≤0.15) ✓
   - With announcement: moderate (0.45-0.55) ✓
   - With witnesses: moderate (0.35-0.45) ✓
   - With both: high (0.75-0.85) ✓

5. **Integration** (1 test)
   - coherence_index() uses spatial coherence correctly ✓
   - Impossible travel tanks overall CI (<0.5) ✓

## Validation Summary

### Session 104 Fix Confirmed ✅

1. **Security Property Enforced**
   - Impossible travel: CI = 0.1 (was 0.45)
   - 78% reduction in false negative risk
   - Critical dimensions floor overall CI

2. **No False Positives**
   - Legitimate travel: CI = 0.84-0.91
   - Fast but possible travel: CI = 0.83
   - Recovery mechanisms still work (announcements, witnesses)

3. **All Tests Pass**
   - Aggregation comparison: 3/3 ✅
   - Spatial coherence: 15/15 ✅
   - Total: 18/18 tests pass

## Attack Vector Mitigation

### Before Session 104 (Geometric Mean)

**Impossible Travel Attack**:
- Attacker spoofs location Tokyo while actually at Portland
- Spatial coherence = 0.1 (impossible travel detected)
- Other dims high: temporal=0.9, capability=0.9, relational=0.9
- **Overall CI = 0.455** (fractional exponents mask low spatial)
- Result: Attack not effectively penalized

### After Session 104 (Min-Weighted-Critical)

**Same Attack**:
- Attacker spoofs location Tokyo while actually at Portland
- Spatial coherence = 0.1 (impossible travel detected)
- Other dims high: temporal=0.9, capability=0.9, relational=0.9
- **Overall CI = 0.100** (floored by critical spatial dimension)
- Result: Attack properly penalized, ATP costs ~8x higher

## Performance Impact

### ATP Cost Scaling

With CIModulationConfig default (ci_breakpoint=0.6, max_multiplier=10.0):

| Scenario | CI | ATP Multiplier | Cost Impact |
|----------|-----|----------------|-------------|
| Legitimate (old) | 0.908 | 1.0x | Baseline |
| Legitimate (new) | 0.840 | 1.0x | No change |
| Impossible (old) | 0.455 | ~2.5x | Moderate penalty |
| Impossible (new) | 0.100 | ~8.0x | Severe penalty |

**Security Improvement**: 3.2x stronger penalty for impossible travel

## Recommendations

### 1. Production Deployment ✅

The min-weighted-critical aggregation strategy is **ready for production**:
- Clear security semantics
- No false positives in testing
- Proper penalty for attack vectors
- All tests passing

### 2. Monitoring

Monitor for edge cases:
- Multiple low critical dimensions (spatial=0.3, capability=0.3)
- Legitimate fast travel patterns (flights, trains)
- Witness vouching effectiveness

### 3. Future Work

Consider:
- Adaptive velocity profiles based on entity history
- Time-of-day awareness (flights at night)
- Geographic region awareness (domestic vs international)

## Conclusion

Session 104's coherence aggregation fix is **validated and working correctly**:

1. ✅ Impossible travel now CI=0.1 (was 0.45) - 78% improvement
2. ✅ Legitimate travel unaffected (CI=0.84-0.91)
3. ✅ Security property maintained (critical dims floor CI)
4. ✅ All 18 tests pass
5. ✅ ATP penalties 3.2x stronger for attacks

**Track 2 Complete**: Aggregation strategy validated across all scenarios.

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*Session 105 Track 2*
*Autonomous Web4 Research - 2025-12-29*
*Generated with Claude Code*
