fix: clear detected credential after settlement to prevent double-settle

packages/atxp-server/src/atxpContext.ts

@@ -78,6 +78,18 @@ export function setDetectedCredential(credential: DetectedCredential): void {
   }
 }
 
+/**
+ * Clear the payment credential from the ATXP context after successful settlement.
+ * Prevents a second requirePayment() call in the same request from trying to
+ * settle the same already-consumed credential.
+ */
+export function clearDetectedCredential(): void {
+  const context = contextStorage.getStore();
+  if (context) {
+    context.detectedCredential = undefined;
+  }
+}
+
 /**
  * Get the pending payment challenge (set by omniChallengeMcpError).
  * Used by atxpExpress to rewrite wrapped tool errors into JSON-RPC errors.

packages/atxp-server/src/requirePayment.ts

@@ -1,7 +1,7 @@
 import { RequirePaymentConfig, extractNetworkFromAccountId, extractAddressFromAccountId, Network, AuthorizationServerUrl } from "@atxp/common";
 import { McpError } from "@modelcontextprotocol/sdk/types.js";
 import { BigNumber } from "bignumber.js";
-import { getATXPConfig, atxpAccountId, atxpToken, getDetectedCredential, setPendingPaymentChallenge } from "./atxpContext.js";
+import { getATXPConfig, atxpAccountId, atxpToken, getDetectedCredential, clearDetectedCredential, setPendingPaymentChallenge } from "./atxpContext.js";
 import { buildPaymentOptions, omniChallengeMcpError } from "./omniChallenge.js";
 import { getATXPResource } from "./atxpContext.js";
 import { ProtocolSettlement, type SettlementContext } from "./protocol.js";
@@ -50,6 +50,9 @@ export async function requirePayment(paymentConfig: RequirePaymentConfig): Promi
   const detectedCredential = getDetectedCredential();
   if (detectedCredential) {
     await settleDetectedCredential(config, detectedCredential, charge, destinationAccountId, paymentAmount);
+    // Clear the credential so a second requirePayment() call in the same request
+    // (e.g., image server's post-generation charge) doesn't try to re-settle it.
+    clearDetectedCredential();
     // After settlement, the ledger should be credited. Fall through to charge below.
   }