HARNESS · BUNDLE EVIDENCE
orders/refunds
DIVERGEDparity 99.94% · 1 counterexampleSELF-CHECK ✓
SMALLEST COUNTEREXAMPLE
fixture fx-0231 · smallest failing input the harness could find
REQUEST
POST /v2/orders/ord_552901/refunds
{
"amountCents": 4900,
"reason": "customer_request",
"currency": "USD"
}
LEGACY RESPONSE
HTTP/1.1 200 OK
{
"refundId": "rf_8831204",
"orderId": "ord_552901",
"status": "completed",
"totalCents": 4899,
"currency": "USD"
}
CANDIDATE RESPONSE
HTTP/1.1 200 OK
{
"refundId": "rf_8831204",
"orderId": "ord_552901",
"status": "completed",
"totalCents": 4901,
"currency": "USD"
}
differing field: response.body.totalCents — legacy 4899 → candidate 4901
NORMALIZATION LEDGER — EVERY EXCLUDED FIELD + WHY
X-Request-Id (request header)regenerated on every replay attempt — correlates a call to its trace, carries no business meaning
traceparent / X-B3-TraceId (request + response headers)APM trace-propagation ids, unique per run by design — comparing them would fail every replay
Set-Cookie (response header)candidate mints a fresh session token on every replay; the value is opaque and non-deterministic on both stacks
response.headers.DateHTTP wall-clock stamp — always "now" at response time, legacy and candidate run milliseconds apart even in lockstep replay
response.body.processedAtapplication-level timestamp, same reason as Date — excluded everywhere it appears in a payload
response.body.requestDurationMsreplay-infra timing artifact, not application logic — comparing it would fail on hardware speed alone
REPLAY RECIPE — the exact commands
$ harness lab up orders-legacy
READY · pinned rails 3.2 image · booted 42s
$ harness record orders refunds
captured 1,860 fixtures + 4,014 mbus events → fx-set-2026-07-18
$ harness verify orders refunds
DIVERGED · parity 99.94% · exit 1
counterexample fx-0231 · response.body.totalCents: 4899 → 4901
$ harness explain orders/refunds/fx-0231
rounding drift in refund path · counterexample.md + replay-recipe.sh
SELF-CHECK ✓ — record → replay(legacy) → PARITY. This run's verdict is trusted, independent of orders/refunds's own diverged outcome.