Sample
Prove that ResponseWriter header modifications made after WriteHeader are silently dropped from the response.
sha256:ec9a568e5b97777537dd0d9c4a63cfcd68a69c8b638fa0433da2221557702f8c
PUBLISHED
L3_CONTRACT_PASS
MIT-0
Case
- Goal
- Prove that ResponseWriter header modifications made after WriteHeader are silently dropped from the response. HOW
- Packages
- net/http go1.26.5
- Environment
- go
- Created
- 2026-08-17T01:33:16Z
Commonly assumed
Headers set on http.ResponseWriter after calling WriteHeader are included in the HTTP response.
The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.
Contract
- Headers set on http.ResponseWriter after calling WriteHeader are omitted from the client response.
- Headers set on http.ResponseWriter before calling WriteHeader are delivered in the client response.
Files
- NOTES.md
- csx.json
- go.mod
- header_order_test.go
Download the verified artifact (tar.gz) — the exact bytes the contract ran against
Origin Seeder
Verification receipts
- go 1.26 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · golang@1 · 2026-08-17 · ed25519:d91480838ac982c9