refactor: extract amendmentCombinations; document vault-share freeze checks

- Move amendmentCombinations algorithm to jtx::amendmentCombinations in
  test/jtx/utility.h+cpp; it was copy-pasted into both AMM_test and
  AMMMPT_test. AMM_test retains a one-liner wrapper that seeds from its
  local testableAmendments() (strips SAV/Lending).
- Document the isVaultPseudoAccountFrozen sub-step in the Doxygen for
  checkWithdrawFreeze and checkDepositFreeze; the MPT-only transitive
  freeze check occurs between the listed steps 1 and 2 in each function.
- Expand the IgnoreFreeze comment in VaultWithdraw::doApply to explain
  why preclaim validation makes the flag safe to use post-fix330.

include/xrpl/ledger/helpers/TokenHelpers.h

@@ -72,9 +72,6 @@ isIndividualFrozen(ReadView const& view, AccountID const& account, Asset const&
 [[nodiscard]] TER
 checkIndividualFrozen(ReadView const& view, AccountID const& account, Asset const& asset);
 
-[[nodiscard]] TER
-checkIndividualDeepFrozen(ReadView const& view, AccountID const& account, Asset const& asset);
-
 /**
  *   isFrozen check is recursive for MPT shares in a vault, descending to
  *   assets in the vault, up to maxAssetCheckDepth recursion depth. This is
@@ -149,6 +146,9 @@ checkDeepFrozen(ReadView const& view, AccountID const& account, Asset const& ass
  * Otherwise checks, in order:
  *   1. checkFrozen(sourceAcct, asset)   — the pseudo-account's trustline /
  *      global freeze must not block sending.
+ *   1a. For MPT assets: isVaultPseudoAccountFrozen(sourceAcct, asset) —
+ *       the pseudo-account's vault share must not be transitively frozen
+ *       via its underlying asset.
  *   2. checkFrozen(submitterAcct, asset) — skipped when submitter == dst
  *      (self-withdrawal); a regular freeze should not prevent recovering
  *      one's own funds.
@@ -176,6 +176,9 @@ checkWithdrawFreeze(
  * Checks, in order:
  *   1. checkFrozen(srcAcct, asset)  — the depositor must not be frozen
  *      (global or individual) for the asset.
+ *   1a. For MPT assets: isVaultPseudoAccountFrozen(dstAcct, asset) —
+ *       the pseudo-account's vault share must not be transitively frozen
+ *       via its underlying asset.
  *   2. checkFrozen(dstAcct, asset)  — the pseudo-account must not be
  *      frozen for the asset.  Unlike regular accounts, pseudo-accounts
  *      cannot receive deposits under a regular freeze because the

src/libxrpl/tx/transactors/vault/VaultWithdraw.cpp

@@ -272,7 +272,10 @@ VaultWithdraw::doApply()
         return tecPATH_DRY;
     }
 
-    // Post-fixCleanup3_3_0: preclaim already handles freeze checks
+    // Post-fixCleanup3_3_0: preclaim already validated all freeze conditions
+    // (checkWithdrawFreeze), so IgnoreFreeze avoids a redundant check that
+    // would incorrectly return zero for vault pseudo-accounts whose shares
+    // are frozen via a transitively frozen underlying asset.
     auto const freezeHandling = view().rules().enabled(fixCleanup3_3_0)
         ? FreezeHandling::IgnoreFreeze
         : FreezeHandling::ZeroIfFrozen;

src/test/app/AMM_test.cpp

@@ -19,6 +19,7 @@
 #include <test/jtx/ter.h>
 #include <test/jtx/trust.h>
 #include <test/jtx/txflags.h>
+#include <test/jtx/utility.h>
 
 #include <xrpl/basics/Number.h>
 #include <xrpl/basics/base_uint.h>
@@ -86,19 +87,11 @@ private:
         return jtx::testableAmendments() - featureSingleAssetVault - featureLendingProtocol;
     }
 
-    // All 2^N permutations of testableAmendments() with each subset of the
-    // given features excluded.
+    // Seed from the local testableAmendments() which strips SAV and Lending.
     static std::vector<FeatureBitset>
     amendmentCombinations(std::initializer_list<uint256> features)
     {
-        std::vector<FeatureBitset> result{testableAmendments()};
-        for (auto const& f : features)
-        {
-            auto const n = result.size();
-            for (std::size_t i = 0; i < n; ++i)
-                result.push_back(result[i] - f);
-        }
-        return result;
+        return jtx::amendmentCombinations(features, testableAmendments());
     }
 
     void

src/test/jtx/impl/utility.cpp

@@ -1,6 +1,7 @@
 #include <test/jtx/utility.h>
 
 #include <test/jtx/Account.h>
+#include <test/jtx/Env.h>
 
 #include <xrpld/rpc/RPCCall.h>
 
@@ -101,4 +102,17 @@ cmdToJSONRPC(std::vector<std::string> const& args, beast::Journal j, unsigned in
     return jv;
 }
 
+std::vector<FeatureBitset>
+amendmentCombinations(std::initializer_list<uint256> features, FeatureBitset seed)
+{
+    std::vector<FeatureBitset> result{seed};
+    for (auto const& f : features)
+    {
+        auto const n = result.size();
+        for (std::size_t i = 0; i < n; ++i)
+            result.push_back(result[i] - f);
+    }
+    return result;
+}
+
 }  // namespace xrpl::test::jtx

src/test/jtx/utility.h

@@ -1,12 +1,16 @@
 #pragma once
 
 #include <test/jtx/Account.h>
+#include <test/jtx/Env.h>
 
 #include <xrpl/json/json_value.h>
 #include <xrpl/ledger/Ledger.h>
+#include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/STObject.h>
 
+#include <initializer_list>
 #include <stdexcept>
+#include <vector>
 
 namespace xrpl::test::jtx {
 
@@ -51,4 +55,16 @@ fillSeq(json::Value& jv, ReadView const& view);
 json::Value
 cmdToJSONRPC(std::vector<std::string> const& args, beast::Journal j, unsigned int apiVersion);
 
+/**
+ * Returns all 2^N permutations of a seed FeatureBitset with each subset of
+ * the given features excluded.  The seed is included as the first element.
+ *
+ * Useful for running a test over every combination of optional amendments
+ * so that each case is exercised both with and without each feature.
+ */
+std::vector<FeatureBitset>
+amendmentCombinations(
+    std::initializer_list<uint256> features,
+    FeatureBitset seed = testableAmendments());
+
 }  // namespace xrpl::test::jtx