fix(stripe): reject idempotent-replayed PaymentIntents in charge verification

src/main/java/com/stripe/mpp/methods/stripe/StripeApi.java

@@ -20,32 +20,41 @@ class StripeApi {
  static final class Result {
  private final String id;
  private final String status;
+ private final boolean idempotentReplayed;
 
  Result(String id, String status) {
+ this(id, status, false);
+ }
+
+ Result(String id, String status, boolean idempotentReplayed) {
  this.id = id;
  this.status = status;
+ this.idempotentReplayed = idempotentReplayed;
  }
 
  String id() { return id; }
  String status() { return status; }
+ boolean idempotentReplayed() { return idempotentReplayed; }
 
  @Override
  public boolean equals(Object o) {
  if (this == o) return true;
  if (!(o instanceof Result)) return false;
  Result result = (Result) o;
  return Objects.equals(id, result.id)
- && Objects.equals(status, result.status);
+ && Objects.equals(status, result.status)
+ && idempotentReplayed == result.idempotentReplayed;
  }
 
  @Override
  public int hashCode() {
- return Objects.hash(id, status);
+ return Objects.hash(id, status, idempotentReplayed);
  }
 
  @Override
  public String toString() {
- return "Result[id=" + id + ", status=" + status + "]";
+ return "Result[id=" + id + ", status=" + status
+ + ", idempotentReplayed=" + idempotentReplayed + "]";
  }
  }
 
@@ -77,7 +86,16 @@ Result createAndConfirm(
  .build();
 
  PaymentIntent pi = client.paymentIntents().create(builder.build(), options);
- return new Result(pi.getId(), pi.getStatus());
+
+ boolean idempotentReplayed = false;
+ if (pi.getLastResponse() != null) {
+ idempotentReplayed = pi.getLastResponse().headers()
+ .firstValue("Idempotent-Replayed")
+ .map(Boolean::parseBoolean)
+ .orElse(false);
+ }
+
+ return new Result(pi.getId(), pi.getStatus(), idempotentReplayed);
 
  } catch (StripeException e) {
  throw new VerificationFailedException(e.getMessage());

src/main/java/com/stripe/mpp/methods/stripe/StripeChargeIntent.java

@@ -103,6 +103,10 @@ public Receipt verify(Credential credential, Map<String, Object> request) {
  StripeApi.Result result = stripeApi.createAndConfirm(
  secretKey, amountMinorUnits, currency, spt, paymentMethodTypes, metadata, challengeId);
 
+ if (result.idempotentReplayed()) {
+ throw new VerificationFailedException(
+ "PaymentIntent " + result.id() + " was an idempotent replay, not a fresh charge");
+ }
  if ("requires_action".equals(result.status())) {
  throw new com.stripe.mpp.error.PaymentActionRequiredException(
  "PaymentIntent " + result.id() + " requires action");

src/test/java/com/stripe/mpp/methods/stripe/StripeChargeIntentTest.java

@@ -97,6 +97,21 @@ void successfulChargeReturnsReceipt() {
  assertThat(receipt.externalId()).isNull();
  }
 
+ @Test
+ void idempotentReplayedSucceededChargeIsRejected() {
+ // Regression test for AGR-2026-035: Stripe reporting a succeeded
+ // PaymentIntent whose creation was an idempotent replay (i.e. the
+ // charge already happened for an earlier challenge/SPT pair) must
+ // not be accepted as a fresh successful verification.
+ StubStripeApi api = new StubStripeApi(
+ new StripeApi.Result("pi_replay123", "succeeded", true));
+
+ assertThatThrownBy(() -> intent(api).verify(credential("spt_xxx"), REQUEST))
+ .isInstanceOf(VerificationFailedException.class)
+ .hasMessageContaining("pi_replay123")
+ .hasMessageContaining("replay");
+ }
+
  @Test
  void externalIdIncludedInReceipt() {
  StubStripeApi api = new StubStripeApi(new StripeApi.Result("pi_abc123", "succeeded"));