Pattern Proposal: Pure Functional Metric Evaluation

Summary

Derive health status and diagnostic reasoning through pure, stateless evaluation functions rather than mutable object state.

Candidate Pattern

• ID: pure-functional-metric-evaluation
• Classification: architectural
• Maturity: strategic_direction
• Type: emerging

Observed Signals

No specific signals listed.

Evidence

Supporting Evidence

• src/cas_runner/dashboard/health_model.py (HealthStatus, calculate_health, get_health_reasons) - Pure functions evaluating domain metrics into HealthStatus and human-readable diagnostic lists.

Scope Assessment

• Evidence Strength: high
• Confidence: high
• Applies to: ideas-to-life-cas

Rationale

• Intent: Compute health levels and explanation messages deterministically from raw status metrics without side effects.
• Context: Dashboard and CLI report operational health based on inventory statistics, compliance violations, and execution traces.
• Force: Mutable metrics state can lead to race conditions or inconsistent reporting
• Force: Calculating aggregate health scores in multiple places causes logic divergence

Traceability

Artifact source: proposed-patterns