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The Driftproof receipt for prototype on Claude Opus 5.5, dated 2026-10-18, and what it can say.

prototype on claude-opus-5-5

Run on 2026-10-18, runner 0.22.2, surface claude-cli, verification level TESTED.

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.

driftproof badge: passing on claude-opus-5-5, 2026-10-18

The two arms

armmeanspread across casescases
with the skill0.929± 0.1233
without the skill0.363± 0.1303

Lift +0.566, ± 0.179. 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.

The two arms of this receipt drawn as ranges, with the effect floor marked. 0 0.25 0.5 0.75 1 separated without the skill 0.363 with the skill 0.929

What was verified

receipt_hash verified when this page was built from receipts/skill-measurements/published/ec6755415c717a42fe33a73514157cb0bc76f757971ffa4554de9b4c1a47689c.json; run.transcripts records retained-local.

Receipt hash: 8a22b747d44275755d3d236e3ed3fe09942ada0de2492562b1a0e64dc7750d59

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/skill-measurements/published/ec6755415c717a42fe33a73514157cb0bc76f757971ffa4554de9b4c1a47689c.json

npx driftproof@0.22.4 validate ec6755415c717a42fe33a73514157cb0bc76f757971ffa4554de9b4c1a47689c.json

Embed the badge

[![driftproof](https://driftproofhq.com/r/8a22b747d44275755d3d236e3ed3fe09942ada0de2492562b1a0e64dc7750d59/badge.svg)](https://driftproofhq.com/r/8a22b747d44275755d3d236e3ed3fe09942ada0de2492562b1a0e64dc7750d59/)