Function HashRequest

internal/idempotency/store.go:120–126

HashRequest mixes the request path into the body hash so the same Idempotency-Key cannot accidentally replay a cached response across different routes (e.g. reusing a key set on a reply to message A while replying to message B). The path is included on its own line before the body so the hash is una

(path string, body []byte)

// Callers compute this once with the raw body bytes they already
// have and pass the result to Store.Claim.
func HashRequest(path string, body []byte) string {
	h := sha256.New()
	h.Write([]byte(path))
	h.Write([]byte{'\n'})
	h.Write(body)
	return hex.EncodeToString(h.Sum(nil))
}

// Claim atomically reserves (userID, key) for the caller. The outcome
// determines what the HTTP layer should do next: