feat(tempo)!: remove custom memos

README.md

@@ -24,6 +24,12 @@ implementation 'com.stripe:mpp-java:0.1.4'
 </dependency>
 ```
 
+## Breaking change: custom Tempo memos
+
+`TempoMethod.Builder.memo(...)` and `Method.memo()` have been removed. Remove these
+configurations and overrides; clients use automatic challenge-bound attribution
+memos. Direct Tempo verification rejects explicit memos in payment requests.
+
 ## Usage
 
 ### Testnet

src/main/java/com/stripe/mpp/methods/tempo/Attribution.java

@@ -11,7 +11,7 @@
 /**
  * MPP attribution memo encoding for TIP-20 {@code transferWithMemo}.
  *
- * <p>When the merchant does not set an explicit memo, Tempo clients write this
+ * <p>Tempo clients write this
  * 32-byte value so a payment can be bound to a specific challenge. Layout:
  *
  * <pre>

src/main/java/com/stripe/mpp/methods/tempo/TempoChargeIntent.java

@@ -29,7 +29,7 @@
  * </ul>
  *
  * <p>A qualifying Transfer of the requested token, recipient and amount is not
- * enough. Unless the merchant set an explicit memo, the matched logs must include
+ * enough. The matched logs must include
  * a {@code TransferWithMemo} whose memo is bound to this challenge (MPP attribution
  * tag, server fingerprint of the challenge realm, and nonce
  * {@code keccak256(challengeId)[0..6]}). That is what stops a third party from
@@ -102,6 +102,9 @@ public TempoChargeIntent(String rpcUrl, Store store) {
     @Override
     @SuppressWarnings("unchecked")
     public Receipt verify(Credential credential, Map<String, Object> request) {
+        if (memoFrom(request) != null) {
+            throw new VerificationFailedException("explicit memos are not supported for direct Tempo charge verification");
+        }
         if (!(credential.payload() instanceof Map<?, ?>)) {
             throw new VerificationFailedException("missing or invalid payload");
         }
@@ -160,9 +163,7 @@ private Receipt awaitReceipt(
                         "transaction logs contain no Transfer matching the request currency, recipient, and amount"
                     );
                 }
-                if (memoFrom(request) == null) {
-                    assertChallengeBoundMemo(matched, credential);
-                }
+                assertChallengeBoundMemo(matched, credential);
                 return Receipt.success(txHash, "tempo");
             }
             if (i < maxRetries - 1) {
@@ -179,7 +180,7 @@ private Receipt awaitReceipt(
 
     /**
      * Collects ERC-20 Transfer / TransferWithMemo logs that match the request's
-     * currency, recipient, amount, expected sender, and (when set) merchant memo.
+     * currency, recipient, amount, and expected sender.
      *
      * <p>The request amount must already be in atomic units (i.e. after
      * transformRequest has run).
@@ -193,7 +194,6 @@ private List<MatchedLog> matchTransferLogs(
         String currency  = (String) request.get("currency");
         String recipient = (String) request.get("recipient");
         String amountStr = (String) request.get("amount");
-        String expectedMemo = normalizeMemo(memoFrom(request));
 
         if (currency == null || recipient == null || amountStr == null) return List.of();
 
@@ -222,19 +222,13 @@ private List<MatchedLog> matchTransferLogs(
             boolean isTransferWithMemo = TRANSFER_WITH_MEMO_TOPIC.equalsIgnoreCase(topic0);
             if (!isTransfer && !isTransferWithMemo) continue;
             if (isTransferWithMemo && topics.size() < 4) continue;
-            if (expectedMemo != null && !isTransferWithMemo) continue;
 
             String fromAddress = "0x" + topics.get(1).substring(topics.get(1).length() - 40);
             String toAddress   = "0x" + topics.get(2).substring(topics.get(2).length() - 40);
 
             if (!toAddress.equalsIgnoreCase(recipient)) continue;
             if (expectedSender != null && !fromAddress.equalsIgnoreCase(expectedSender)) continue;
 
-            if (expectedMemo != null) {
-                String logMemo = normalizeMemo(topics.get(3));
-                if (logMemo == null || !logMemo.equals(expectedMemo)) continue;
-            }
-
             String data = (String) log.get("data");
             if (data == null || data.length() < 66) continue;
 
@@ -317,14 +311,6 @@ static String memoFrom(Map<String, Object> request) {
         return null;
     }
 
-    static String normalizeMemo(String memo) {
-        if (memo == null) return null;
-        String value = memo.trim();
-        if (value.isEmpty()) return null;
-        if (!value.startsWith("0x") && !value.startsWith("0X")) value = "0x" + value;
-        return value.toLowerCase(Locale.ROOT);
-    }
-
     static final class ParsedPkh {
         final String address;
         final int chainId;

src/main/java/com/stripe/mpp/methods/tempo/TempoMethod.java

@@ -26,26 +26,20 @@ public class TempoMethod implements Method {
     private final String rpcUrl;
     private final int chainId;
     private final int decimals;
-    private final String memo;
     private final TempoChargeIntent chargeIntent;
 
     TempoMethod(String rpcUrl, int chainId) {
-        this(rpcUrl, chainId, TempoDefaults.DEFAULT_DECIMALS, null, null, null);
+        this(rpcUrl, chainId, TempoDefaults.DEFAULT_DECIMALS, null, null);
     }
 
     TempoMethod(String rpcUrl, int chainId, int decimals, TempoRelay relay) {
-        this(rpcUrl, chainId, decimals, relay, null, null);
+        this(rpcUrl, chainId, decimals, relay, null);
     }
 
     TempoMethod(String rpcUrl, int chainId, int decimals, TempoRelay relay, Store store) {
-        this(rpcUrl, chainId, decimals, relay, store, null);
-    }
-
-    TempoMethod(String rpcUrl, int chainId, int decimals, TempoRelay relay, Store store, String memo) {
         this.rpcUrl = rpcUrl;
         this.chainId = chainId;
         this.decimals = decimals;
-        this.memo = memo;
         this.chargeIntent = relay == null
             ? new TempoChargeIntent(rpcUrl, store != null ? store : new MemoryStore())
             : new TempoRelayChargeIntent(rpcUrl, relay);
@@ -66,7 +60,6 @@ public static final class Builder {
         private int    chainId  = TempoDefaults.MAINNET_CHAIN_ID;
         private TempoRelay relay;
         private Store store;
-        private String memo;
 
         private Builder() {}
 
@@ -103,28 +96,13 @@ public Builder store(Store store) {
             return this;
         }
 
-        /**
-         * Sets an explicit TIP-20 memo that payments must match.
-         *
-         * <p>When omitted, clients write an MPP attribution memo bound to the
-         * challenge and the server requires that binding. An explicit memo is
-         * matched exactly and is not challenge-bound — the caller must make it
-         * unique per challenge if hash reuse across challenges should be rejected.
-         */
-        public Builder memo(String memo) {
-            this.memo = Objects.requireNonNull(memo, "memo");
-            return this;
-        }
-
         public TempoMethod build() {
-            return new TempoMethod(rpcUrl, chainId, TempoDefaults.DEFAULT_DECIMALS, relay, store, memo);
+            return new TempoMethod(rpcUrl, chainId, TempoDefaults.DEFAULT_DECIMALS, relay, store);
         }
     }
 
     @Override public String name() { return "tempo"; }
 
-    @Override public String memo() { return memo; }
-
     public int chainId() { return chainId; }
     public String rpcUrl() { return rpcUrl; }
     /** Returns the CAIP-2 network string (e.g. {@code "eip155:4217"}) for display purposes. */
@@ -154,11 +132,7 @@ public Map<String, Object> transformRequest(Map<String, Object> request) {
                 .toString();
             Map<String, Object> result = new LinkedHashMap<>(request);
             result.put("amount", atomic);
-            Map<String, Object> methodDetails = new LinkedHashMap<>();
-            methodDetails.put("chainId", chainId);
-            Object requestMemo = result.get("memo");
-            if (requestMemo != null) methodDetails.put("memo", requestMemo);
-            result.put("methodDetails", methodDetails);
+            result.put("methodDetails", Map.of("chainId", chainId));
             return result;
         } catch (Exception e) {
             throw new IllegalArgumentException("invalid amount: " + amount, e);

src/main/java/com/stripe/mpp/server/Method.java

@@ -18,9 +18,6 @@ public interface Method {
      */
     List<Class<? extends Intent>> intents();
 
-    /** Optional: blockchain/network memo field. */
-    default String memo() { return null; }
-
     /** Optional: fee payer address. */
     default String feePayer() { return null; }
 

src/main/java/com/stripe/mpp/server/MppHandler.java

@@ -121,7 +121,6 @@ public VerifyResult charge(
         request.put("amount",    resolvedAmount);
         request.put("currency",  resolvedCurrency);
         request.put("recipient", resolvedRecipient);
-        if (method.memo()     != null) request.put("memo",      method.memo());
         if (method.feePayer() != null) request.put("fee_payer", method.feePayer());
         if (method.chain()    != null) request.put("chain",     method.chain());
 
@@ -203,7 +202,6 @@ Map<String, Object> buildRequest(ChargeDescriptor d) {
         request.put("amount",    resolvedAmount);
         request.put("currency",  resolvedCurrency);
         request.put("recipient", resolvedRecipient);
-        if (method.memo()     != null) request.put("memo",      method.memo());
         if (method.feePayer() != null) request.put("fee_payer", method.feePayer());
         if (method.chain()    != null) request.put("chain",     method.chain());
 

src/test/java/com/stripe/mpp/methods/tempo/TempoChargeIntentTest.java

@@ -8,6 +8,7 @@
 import com.stripe.mpp.store.Store;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
 import org.junit.jupiter.params.provider.ValueSource;
 
 import java.util.HashMap;
@@ -113,14 +114,18 @@ static class StubRpc extends TempoRpc {
         private final Map<String, Object> receipt;
         private final int nullReceiptsBeforeResult;
         private int receiptCalls = 0;
+        private int sendCalls = 0;
 
         StubRpc(String txHashOnSend, Map<String, Object> receipt, int nullReceiptsBeforeResult) {
             this.txHashOnSend = txHashOnSend;
             this.receipt = receipt;
             this.nullReceiptsBeforeResult = nullReceiptsBeforeResult;
         }
 
-        @Override String sendRawTransaction(String rpcUrl, String rawTx) { return txHashOnSend; }
+        @Override String sendRawTransaction(String rpcUrl, String rawTx) {
+            sendCalls++;
+            return txHashOnSend;
+        }
 
         @Override Map<String, Object> getTransactionReceipt(String rpcUrl, String txHash) {
             return receiptCalls++ < nullReceiptsBeforeResult ? null : receipt;
@@ -408,58 +413,35 @@ void pushAcceptsChallengeBoundMemoAlongsideAPlainTransfer() {
         assertThat(result.status()).isEqualTo("success");
     }
 
-    @Test
-    void explicitMemoMustMatchExactly() {
-        String merchantMemo = "0x" + "ab".repeat(32);
-        Map<String, Object> request = new HashMap<>(REQUEST);
-        request.put("memo", merchantMemo);
-
-        Receipt result = intent(new StubRpc(null,
-            receiptWithMemoLog(TOKEN_CONTRACT, SENDER, RECIPIENT, AMOUNT_ATOMIC, merchantMemo), 0))
-            .verify(hashCredential("0xpushedtx"), request);
-        assertThat(result.status()).isEqualTo("success");
-    }
-
-    @Test
-    void explicitMemoMismatchIsRejected() {
+    @ParameterizedTest
+    @CsvSource({
+        "hash, false, false", "hash, false, true",
+        "hash, true, false", "hash, true, true",
+        "transaction, false, false", "transaction, false, true",
+        "transaction, true, false", "transaction, true, true"
+    })
+    void explicitMemoIsRejectedBeforeRpc(String type, boolean nested, boolean declaredPayer) {
         String merchantMemo = "0x" + "ab".repeat(32);
-        String otherMemo = "0x" + "cd".repeat(32);
         Map<String, Object> request = new HashMap<>(REQUEST);
-        request.put("memo", merchantMemo);
+        if (nested) {
+            request.put("methodDetails", Map.of("chainId", CHAIN_ID, "memo", merchantMemo));
+        } else {
+            request.put("memo", merchantMemo);
+        }
+        Credential credential = new Credential(ECHO,
+            "hash".equals(type) ? Map.of("type", type, "hash", "0xstolen")
+                : Map.of("type", type, "signature", "0xsignedtx"),
+            declaredPayer ? didPkh(CHAIN_ID, SENDER) : null);
+        StubRpc rpc = new StubRpc("0xstolen",
+            receiptWithMemoLog(TOKEN_CONTRACT, SENDER, RECIPIENT, AMOUNT_ATOMIC, merchantMemo), 0);
+        Store store = new MemoryStore();
 
-        assertThatThrownBy(() -> intent(new StubRpc(null,
-            receiptWithMemoLog(TOKEN_CONTRACT, SENDER, RECIPIENT, AMOUNT_ATOMIC, otherMemo), 0))
-            .verify(hashCredential("0xpushedtx"), request))
+        assertThatThrownBy(() -> intent(rpc, store).verify(credential, request))
             .isInstanceOf(VerificationFailedException.class)
-            .hasMessageContaining("Transfer");
-    }
-
-    @Test
-    void explicitMemoDoesNotRequireChallengeBinding() {
-        String merchantMemo = "0x" + "ab".repeat(32);
-        Map<String, Object> request = new HashMap<>(REQUEST);
-        request.put("memo", merchantMemo);
-
-        Receipt result = intent(new StubRpc(null,
-            receiptWithMemoLog(TOKEN_CONTRACT, SENDER, RECIPIENT, AMOUNT_ATOMIC, merchantMemo), 0))
-            .verify(hashCredential("0xpushedtx"), request);
-        assertThat(result.status()).isEqualTo("success");
-    }
-
-    @Test
-    void explicitMemoInMethodDetailsIsHonored() {
-        String merchantMemo = "0x" + "ab".repeat(32);
-        Map<String, Object> request = Map.of(
-            "amount", String.valueOf(AMOUNT_ATOMIC),
-            "currency", TOKEN_CONTRACT,
-            "recipient", RECIPIENT,
-            "methodDetails", Map.of("chainId", CHAIN_ID, "memo", merchantMemo)
-        );
-
-        Receipt result = intent(new StubRpc(null,
-            receiptWithMemoLog(TOKEN_CONTRACT, SENDER, RECIPIENT, AMOUNT_ATOMIC, merchantMemo), 0))
-            .verify(hashCredential("0xpushedtx"), request);
-        assertThat(result.status()).isEqualTo("success");
+            .hasMessageContaining("explicit memos are not supported");
+        assertThat(rpc.sendCalls).isZero();
+        assertThat(rpc.receiptCalls).isZero();
+        assertThat(store.tryClaim("tempo:hash:0xstolen")).isTrue();
     }
 
     @Test

src/test/java/com/stripe/mpp/methods/tempo/TempoMethodTest.java

@@ -1,8 +1,5 @@
 package com.stripe.mpp.methods.tempo;
 
-import com.stripe.mpp.Mpp;
-import com.stripe.mpp.server.MppHandler;
-import com.stripe.mpp.server.VerifyResult;
 import org.junit.jupiter.api.Test;
 
 import java.util.Map;
@@ -48,37 +45,4 @@ void rejectsAmountWithTooManyDecimalPlaces() {
         )).isInstanceOf(IllegalArgumentException.class);
     }
 
-    @Test
-    void copiesMemoIntoMethodDetails() {
-        Map<String, Object> result = METHOD.transformRequest(Map.of(
-            "amount", "1.000000",
-            "currency", "USDC",
-            "recipient", "0xABC",
-            "memo", "0x" + "ab".repeat(32)
-        ));
-        assertThat(((Map<?, ?>) result.get("methodDetails")).get("chainId")).isEqualTo(1);
-        assertThat(((Map<?, ?>) result.get("methodDetails")).get("memo"))
-            .isEqualTo("0x" + "ab".repeat(32));
-        assertThat(result.get("memo")).isEqualTo("0x" + "ab".repeat(32));
-    }
-
-    @Test
-    void builderMemoIsAdvertisedOnTheMethod() {
-        String memo = "0x" + "cd".repeat(32);
-        TempoMethod method = TempoMethod.custom("http://rpc.example.com", 1).memo(memo).build();
-        assertThat(method.memo()).isEqualTo(memo);
-    }
-
-    @Test
-    void challengeIncludesConfiguredMemo() {
-        String memo = "0x" + "ab".repeat(32);
-        TempoMethod tempo = TempoMethod.custom("http://rpc.example.com", 1).memo(memo).build();
-        MppHandler mpp = Mpp.create(tempo, "api.example.com", "secret");
-
-        VerifyResult result = mpp.charge(null, tempo.chargeIntent(), "1.000000", "USDC", "0xABC");
-
-        Map<String, Object> request = ((VerifyResult.Challenged) result).challenge().request();
-        assertThat(request.get("memo")).isEqualTo(memo);
-        assertThat(((Map<?, ?>) request.get("methodDetails")).get("memo")).isEqualTo(memo);
-    }
 }