The Driftproof receipt for improve-codebase-architecture on Claude Haiku 5.5, from Report 018, dated 2026-11-02, and what it can say.
improve-codebase-architecture on claude-haiku-5-5
Passing
A case separated upward under the band rule. That is a separation detected under the rule, not proof that the skill moved the score.
Skill token cost: +2139 input and +150 output tokens per call against no skill (measured, grading excluded).
The two arms
| arm | mean | spread across cases | cases |
|---|---|---|---|
| with the skill | 0.778 | ± 0.077 | 3 |
| without the skill | 0.546 | ± 0.106 | 3 |
Lift +0.232, ± 0.131. 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/b82af8993f7de808d929929f51237c199fed5b77070457ad5063862817bd3c15.json; run.transcripts records retained-local.
Receipt hash: c1c2abfd0a6ed0e40c98ab4e4eb970ff2e1b40fc67d5ab6c396bf583f5eafc13
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/b82af8993f7de808d929929f51237c199fed5b77070457ad5063862817bd3c15.json
npx driftproof@0.27.0 validate b82af8993f7de808d929929f51237c199fed5b77070457ad5063862817bd3c15.json