The Driftproof receipt for writing-plans on Claude Opus 4.8, from Report 003, dated 2026-08-12, and what it can say.
writing-plans on claude-opus-4-8
Not measured
This receipt carries no verdict: it does not record that a model answered the run.
Skill token cost: about +1722 input tokens per call, estimated from the SKILL.md length (not measured).
The two arms
| arm | mean | spread across cases | cases |
|---|---|---|---|
| with the skill | 0.864 | ± 0.033 | 7 |
| without the skill | 0.578 | ± 0.269 | 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-003/writing-plans__claude-opus-4-8.json; run.transcripts records retained-local.
Receipt hash: 2f6ca2f3db606cd9b6b7815f83b0addb52c7aac6c0591601f54d8f26b85e0775
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-003/writing-plans__claude-opus-4-8.json
npx driftproof@0.28.0 validate writing-plans__claude-opus-4-8.json