The Driftproof receipt for frontend-design on Claude Haiku 5.5, from Report 018, dated 2026-11-02, and what it can say.
frontend-design on claude-haiku-5-5
Regressed
A case separated downward under the band rule. That is a separation detected under the rule, not proof that the skill moved the score.
Skill token cost: +2843 input and +626 output tokens per call against no skill (measured, grading excluded).
The two arms
| arm | mean | spread across cases | cases |
|---|---|---|---|
| with the skill | 0.883 | ± 0.102 | 3 |
| without the skill | 0.865 | ± 0.118 | 3 |
Lift +0.018, ± 0.156. A spread is the sample standard deviation of the per-case means: a descriptive spread with no coverage probability. The verdict above reads each case's two bands, not these aggregates.
This receipt also reads the skill against a same-length placebo. Report 018 shows that reading.
What was verified
receipt_hash verified when this page was built from receipts/report-018/campaign-3/9ab2dca4053dd9795f27a7aff1270acf30494f31e1cf2b294f11e9650adcd98d.json; run.transcripts records retained-local.
Receipt hash: c130a9fcadfdd7ee6cc75f3d3523f2fdb408721574caf5ac6d07032411adca55
Check this file yourself
validate shows that this file is unchanged since it was sealed. It does not show who made it or who sealed it.
curl -fsSLO https://raw.githubusercontent.com/driftproofhq/driftproof/main/receipts/report-018/campaign-3/9ab2dca4053dd9795f27a7aff1270acf30494f31e1cf2b294f11e9650adcd98d.json
npx driftproof@0.27.0 validate 9ab2dca4053dd9795f27a7aff1270acf30494f31e1cf2b294f11e9650adcd98d.json