The Driftproof receipt for code-review-and-quality on Claude Fable 5.1, from Report 008, dated 2026-09-01, and what it can say.
code-review-and-quality on claude-fable-5-1
Not measured
This receipt carries no verdict: it does not record that a model answered the run.
Skill token cost: about +5120 input tokens per call, estimated from the SKILL.md length (not measured).
The two arms
| arm | mean | spread across cases | cases |
|---|---|---|---|
| with the skill | 0.865 | ± 0.036 | 7 |
| without the skill | 0.793 | ± 0.214 | 7 |
No lift is stated for a state that did not measure one. 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.
What was verified
receipt_hash verified when this page was built from receipts/report-008/code-review-and-quality-claude-fable-5-1-2026-09-01.json; run.transcripts records hashes-only.
Receipt hash: 1e6a697783d54e14b98d06a1b682f6801919ebbb62c09120290db9098259183c
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-008/code-review-and-quality-claude-fable-5-1-2026-09-01.json
npx driftproof@0.28.0 validate code-review-and-quality-claude-fable-5-1-2026-09-01.json