Scoring Model¶

Composite Drift Score¶

Individual signal scores are combined into a weighted composite:

\[\text{Score} = \frac{\sum (\text{signal\_weight} \times \text{signal\_score})}{\sum \text{weights}}\]

Count Dampening¶

Logarithmic dampening prevents signals with many low-confidence findings from dominating:

\[\text{signal\_score} = \overline{s} \times \min\!\left(1,\; \frac{\ln(1 + n)}{\ln(1 + k)}\right)\]

\(\overline{s}\) = mean finding score
\(n\) = finding count
\(k\) = dampening constant (default: 10)

Effect: 1 finding at 0.5 → dampened to 0.27. 15 findings at 0.5 → full 0.5.

Default Weights¶

19 signals are currently scoring-active. Weights are normalised at runtime; auto_calibrate (default: on) rebalances based on signal variance.

Signal	Weight	Rationale
Pattern Fragmentation (PFS)	0.16	Highest ablation-study impact on F1
Architecture Violation (AVS)	0.16	Critical for maintainability
Mutant Duplicate (MDS)	0.13	Common AI pattern
Explainability Deficit (EDS)	0.09	Important but noisy
System Misalignment (SMS)	0.08	Cross-module novelty detection
Doc-Implementation Drift (DIA)	0.04	Promoted from report-only (v0.7.0)
Broad Exception Monoculture (BEM)	0.04	Promoted from report-only (v0.7.0)
Test Polarity Deficit (TPD)	0.04	Promoted from report-only (v0.7.0)
Naming Contract Violation (NBV)	0.04	Added in v0.7.0 (ADR-008)
Guard Clause Deficit (GCD)	0.03	Promoted from report-only (v0.7.0)
Bypass Accumulation (BAT)	0.03	Added in v0.7.0 (ADR-008)
Exception Contract Drift (ECM)	0.03	Added in v0.7.1 (ADR-008)
Phantom Reference (PHR)	0.02	Promoted for scoring in ADR-039
Missing Authorization (MAZ)	0.02	Promoted for scoring in ADR-039
Cohesion Deficit (COD)	0.01	Added in v0.7.3 as cohesion-focused coherence detector
Hardcoded Secret (HSC)	0.01	Promoted for scoring in ADR-039
Insecure Default (ISD)	0.01	Promoted for scoring in ADR-039
Co-Change Coupling (CCC)	0.005	Added in v0.8.0 for hidden git-history coupling without explicit imports
Fan-Out Explosion (FOE)	0.005	Promoted for scoring in ADR-039

Report-only Signals (`weight=0.0`)¶

The following signals are intentionally report-only in the default model and do not contribute to the composite score:

Signal	Weight	Status
Temporal Volatility (TVS)	0.0	Report-only pending re-validation
TS Architecture (TSA)	0.0	Report-only
Circular Import (CIR)	0.0	Report-only
Dead Code Accumulation (DCA)	0.0	Report-only
Cognitive Complexity (CXS)	0.0	Report-only

Core weights were originally calibrated via ablation study (remove each signal, measure F1 delta, assign proportional weight). Promoted signals received conservative initial weights. See ADR-003.

Historical note¶

Current default model snapshot: 24 total signals (19 scoring-active, 5 report-only).

The v0.5 benchmark study used 6 core signals at higher weights (PFS=0.22, AVS=0.22, MDS=0.17, TVS=0.17, EDS=0.12, SMS=0.10) with 4 report-only signals at weight 0.00. Precision claims in the study apply to that model. See ADR-007 for the original report-only rationale.

Severity Mapping¶

Score Range	Severity
≥ 0.80	CRITICAL
≥ 0.60 and < 0.80	HIGH
≥ 0.40 and < 0.60	MEDIUM
≥ 0.20 and < 0.40	LOW
< 0.20	INFO

Module-Level Scoring¶

Findings are grouped by module path. Each module receives:

Per-signal scores
Composite score
AI attribution ratio (% findings from AI-generated code)
Top signal identifier