The Driftproof receipt for agent-browser on Claude Opus 5.5, dated 2026-10-18, and what it can say.
agent-browser on claude-opus-5-5
Not enough draws
Not enough draws to conclude at this effect floor.
Draws needed: no draw count at these spreads (case web: the two arms' spreads sum to 0.094, at or above the 0.05 floor).
The two arms
| arm | mean | spread across cases | cases |
|---|---|---|---|
| with the skill | 0.875 | ± 0.124 | 3 |
| without the skill | 0.876 | ± 0.058 | 3 |
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/skill-measurements/published/96b271c97721d0b6609b7885e748533dd164840de83538b88a1ee796ee1f80e5.json; run.transcripts records retained-local.
Receipt hash: 5d537a57fb3d2f578c43ba3c97554ce3f9dd3c875b3749cedfd1a3faa0314af8
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/96b271c97721d0b6609b7885e748533dd164840de83538b88a1ee796ee1f80e5.json
npx driftproof@0.22.4 validate 96b271c97721d0b6609b7885e748533dd164840de83538b88a1ee796ee1f80e5.json