| name | fpf-parity |
| description | Ensure fair comparison conditions before evaluating variants. Produces PAR-* parity plan. SHOULD invoke before /fpf-selection when comparing ≥2 variants with measurable indicators. |
| argument-hint | [comparison-context] |
What this skill IS
This is fairness assurance for comparisons, not bureaucracy. Before declaring one variant better than another, you must ensure the comparison was fair — same budget, same data, same measurement procedure. Without parity, dominance claims are unreliable.
When to invoke
- Before
/fpf-selection when comparing variants with measurable indicators
- When comparing benchmark results across different conditions
- When a variant "won" but you're not sure the comparison was fair
- NOT needed for purely qualitative comparisons (e.g., architectural trade-offs)
Output
.fpf/characterizations/PAR-${CLAUDE_SESSION_ID}--<slug>.md
Constraints (quality bar)
- C1: All candidates listed explicitly
- C2: Budget per candidate stated and equal (compute, time, attempts)
- C3: Environment identical or differences noted with impact assessment
- C4: Indicators from CHR-* referenced — no ad-hoc metrics
- C5: Minimum 2 repetitions with variance reported
- C6: No hidden aggregation — multi-dimensional results, not single score
Format
# Parity Plan
- **ID:** PAR-... **CHR:** CHR-... **Created:** YYYY-MM-DD
## Candidates
(A / B / C — what is being compared)
## Comparator
- Who compares: (role/agent performing the evaluation)
- Comparison method: (automated test | manual review | benchmark harness | ...)
## Equal conditions
- Time window: (same cutoff)
- Budget per candidate: (equal compute/time/attempts)
- Environment: (versions, hardware, config — identical or noted)
- Data/fixtures: (same dataset, same seed-set)
## Measurement
- Indicators: (from CHR-*, subset for this comparison)
- Repetitions: (≥2, with variance reporting)
- Normalization: (explicit rule or "none" with justification)
- Missing data: (how to handle "unknown"/"not measured" — exclude, impute, or flag)
## Result
- Non-dominated set: ...
- Eliminated and why: ...
- valid_until: YYYY-MM-DD
