feat: Move VaultCreate invariants from ValidVault to VaultCreate

Introduce VaultInvariantData to collect vault and MPTokenIssuance
snapshots during visitInvariantEntry, then implement the six
ttVAULT_CREATE-specific post-conditions in VaultCreate::finalizeInvariants
(empty vault, pseudo-account linkage). ValidVault now passes through
ttVAULT_CREATE in its switch, keeping only the universal vault checks and
the cross-transaction sentinel that guards against other tx types creating
vaults.

include/xrpl/tx/invariants/VaultInvariantData.h

@@ -0,0 +1,76 @@
+#pragma once
+
+#include <xrpl/basics/Number.h>
+#include <xrpl/basics/base_uint.h>
+#include <xrpl/protocol/AccountID.h>
+#include <xrpl/protocol/Asset.h>
+#include <xrpl/protocol/MPTIssue.h>
+#include <xrpl/protocol/STLedgerEntry.h>
+
+#include <optional>
+#include <vector>
+
+namespace xrpl {
+
+/**
+ * @brief Collects vault and share-issuance snapshots from ledger entry visits.
+ *
+ * Used by per-transaction invariant checks (e.g. VaultCreate) that need
+ * vault and MPTokenIssuance state without the full balance-delta tracking
+ * that ValidVault maintains.
+ */
+class VaultInvariantData
+{
+public:
+    struct Vault
+    {
+        uint256 key = beast::kZero;
+        Asset asset;
+        AccountID pseudoId;
+        AccountID owner;
+        uint192 shareMPTID = beast::kZero;
+        Number assetsTotal = 0;
+        Number assetsAvailable = 0;
+        Number assetsMaximum = 0;
+        Number lossUnrealized = 0;
+
+        static Vault
+        make(SLE const&);
+    };
+
+    struct Shares
+    {
+        MPTIssue share;
+        std::uint64_t sharesTotal = 0;
+        std::uint64_t sharesMaximum = 0;
+
+        static Shares
+        make(SLE const&);
+    };
+
+    void
+    visitEntry(bool isDelete, SLE::const_ref before, SLE::const_ref after);
+
+    [[nodiscard]] std::vector<Vault> const&
+    afterVaults() const
+    {
+        return afterVault_;
+    }
+
+    [[nodiscard]] std::vector<Vault> const&
+    beforeVaults() const
+    {
+        return beforeVault_;
+    }
+
+    /** Find shares in afterMPTs_ whose mptID matches. */
+    [[nodiscard]] std::optional<Shares>
+    findShares(uint192 const& mptID) const;
+
+private:
+    std::vector<Vault> afterVault_;
+    std::vector<Vault> beforeVault_;
+    std::vector<Shares> afterMPTs_;
+};
+
+}  // namespace xrpl

include/xrpl/tx/transactors/vault/VaultCreate.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <xrpl/tx/Transactor.h>
+#include <xrpl/tx/invariants/VaultInvariantData.h>
 
 namespace xrpl {
 
@@ -38,6 +39,9 @@ public:
         XRPAmount fee,
         ReadView const& view,
         beast::Journal const& j) override;
+
+private:
+    VaultInvariantData data_;
 };
 
 }  // namespace xrpl

src/libxrpl/tx/invariants/VaultInvariant.cpp

@@ -544,61 +544,13 @@ ValidVault::finalize(
     result &= [&]() {
         switch (txnType)
         {
-            case ttVAULT_CREATE: {
-                bool result = true;
-
-                if (!beforeVault_.empty())
-                {
-                    JLOG(j.fatal())  //
-                        << "Invariant failed: create operation must not have "
-                           "updated a vault";
-                    result = false;
-                }
-
-                if (afterVault.assetsAvailable != kZero || afterVault.assetsTotal != kZero ||
-                    afterVault.lossUnrealized != kZero || updatedShares->sharesTotal != 0)
-                {
-                    JLOG(j.fatal())  //
-                        << "Invariant failed: created vault must be empty";
-                    result = false;
-                }
-
-                if (afterVault.pseudoId != updatedShares->share.getIssuer())
-                {
-                    JLOG(j.fatal())  //
-                        << "Invariant failed: shares issuer and vault "
-                           "pseudo-account must be the same";
-                    result = false;
-                }
-
-                auto const sleSharesIssuer =
-                    view.read(keylet::account(updatedShares->share.getIssuer()));
-                if (!sleSharesIssuer)
-                {
-                    JLOG(j.fatal())  //
-                        << "Invariant failed: shares issuer must exist";
-                    return false;
-                }
-
-                if (!isPseudoAccount(sleSharesIssuer))
-                {
-                    JLOG(j.fatal())  //
-                        << "Invariant failed: shares issuer must be a "
-                           "pseudo-account";
-                    result = false;
-                }
-
-                if (auto const vaultId = (*sleSharesIssuer)[~sfVaultID];
-                    !vaultId || *vaultId != afterVault.key)
-                {
-                    JLOG(j.fatal())  //
-                        << "Invariant failed: shares issuer pseudo-account "
-                           "must point back to the vault";
-                    result = false;
-                }
-
-                return result;
-            }
+            case ttVAULT_CREATE:
+            case ttLOAN_SET:
+            case ttLOAN_MANAGE:
+            case ttLOAN_PAY:
+                // Create-specific checks live in VaultCreate::finalizeInvariants.
+                // Loan checks are TBD.
+                return true;
             case ttVAULT_SET: {
                 bool result = true;
 
@@ -1042,13 +994,6 @@ ValidVault::finalize(
                 return result;
             }
 
-            case ttLOAN_SET:
-            case ttLOAN_MANAGE:
-            case ttLOAN_PAY: {
-                // TBD
-                return true;
-            }
-
             default:
                 // LCOV_EXCL_START
                 UNREACHABLE("xrpl::ValidVault::finalize : unknown transaction type");

src/libxrpl/tx/invariants/VaultInvariantData.cpp

@@ -0,0 +1,80 @@
+#include <xrpl/tx/invariants/VaultInvariantData.h>
+
+#include <xrpl/beast/utility/instrumentation.h>
+#include <xrpl/protocol/Indexes.h>
+#include <xrpl/protocol/LedgerFormats.h>
+#include <xrpl/protocol/Protocol.h>
+#include <xrpl/protocol/SField.h>
+#include <xrpl/protocol/STNumber.h>  // IWYU pragma: keep
+
+namespace xrpl {
+
+VaultInvariantData::Vault
+VaultInvariantData::Vault::make(SLE const& from)
+{
+    XRPL_ASSERT(from.getType() == ltVAULT, "VaultInvariantData::Vault::make : from Vault object");
+
+    Vault self;
+    self.key = from.key();
+    self.asset = from.at(sfAsset);
+    self.pseudoId = from.getAccountID(sfAccount);
+    self.owner = from.at(sfOwner);
+    self.shareMPTID = from.getFieldH192(sfShareMPTID);
+    self.assetsTotal = from.at(sfAssetsTotal);
+    self.assetsAvailable = from.at(sfAssetsAvailable);
+    self.assetsMaximum = from.at(sfAssetsMaximum);
+    self.lossUnrealized = from.at(sfLossUnrealized);
+    return self;
+}
+
+VaultInvariantData::Shares
+VaultInvariantData::Shares::make(SLE const& from)
+{
+    XRPL_ASSERT(
+        from.getType() == ltMPTOKEN_ISSUANCE,
+        "VaultInvariantData::Shares::make : from MPTokenIssuance object");
+
+    Shares self;
+    self.share = MPTIssue(makeMptID(from.getFieldU32(sfSequence), from.getAccountID(sfIssuer)));
+    self.sharesTotal = from.getFieldU64(sfOutstandingAmount);
+    self.sharesMaximum = from[~sfMaximumAmount].value_or(kMaxMpTokenAmount);
+    return self;
+}
+
+void
+VaultInvariantData::visitEntry(bool isDelete, SLE::const_ref before, SLE::const_ref after)
+{
+    XRPL_ASSERT(
+        after != nullptr && (before != nullptr || !isDelete),
+        "xrpl::VaultInvariantData::visitEntry : some object is available");
+
+    if (before && before->getType() == ltVAULT)
+        beforeVault_.push_back(Vault::make(*before));
+
+    if (!isDelete && after)
+    {
+        switch (after->getType())
+        {
+            case ltVAULT:
+                afterVault_.push_back(Vault::make(*after));
+                break;
+            case ltMPTOKEN_ISSUANCE:
+                afterMPTs_.push_back(Shares::make(*after));
+                break;
+            default:;
+        }
+    }
+}
+
+std::optional<VaultInvariantData::Shares>
+VaultInvariantData::findShares(uint192 const& mptID) const
+{
+    for (auto const& s : afterMPTs_)
+    {
+        if (s.share.getMptID() == mptID)
+            return s;
+    }
+    return std::nullopt;
+}
+
+}  // namespace xrpl

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

@@ -1,8 +1,10 @@
 #include <xrpl/tx/transactors/vault/VaultCreate.h>
 
+#include <xrpl/basics/Log.h>
 #include <xrpl/basics/Number.h>
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/beast/utility/Zero.h>
+#include <xrpl/beast/utility/instrumentation.h>
 #include <xrpl/core/ServiceRegistry.h>
 #include <xrpl/ledger/View.h>
 #include <xrpl/ledger/helpers/AccountRootHelpers.h>
@@ -263,15 +265,107 @@ VaultCreate::doApply()
 }
 
 void
-VaultCreate::visitInvariantEntry(bool, SLE::const_ref, SLE::const_ref)
+VaultCreate::visitInvariantEntry(bool isDelete, SLE::const_ref before, SLE::const_ref after)
 {
-    // No transaction-specific invariants yet (future work).
+    data_.visitEntry(isDelete, before, after);
 }
 
 bool
-VaultCreate::finalizeInvariants(STTx const&, TER, XRPAmount, ReadView const&, beast::Journal const&)
+VaultCreate::finalizeInvariants(
+    STTx const&,
+    TER result,
+    XRPAmount,
+    ReadView const& view,
+    beast::Journal const& j)
 {
-    // No transaction-specific invariants yet (future work).
+    bool const enforce = view.rules().enabled(featureSingleAssetVault);
+
+    if (!isTesSuccess(result))
+        return true;
+
+    auto const& afterVaults = data_.afterVaults();
+    if (afterVaults.empty())
+        return true;
+
+    auto const& afterVault = afterVaults[0];
+    bool checkResult = true;
+
+    if (!data_.beforeVaults().empty())
+    {
+        JLOG(j.fatal()) << "Invariant failed: create operation must not have updated a vault";
+        checkResult = false;
+    }
+
+    // The MPTokenIssuance may not be in the modified set (e.g. only the vault
+    // was touched in the test), so fall back to a view read if needed.
+    auto const updatedShares = [&]() -> std::optional<VaultInvariantData::Shares> {
+        if (auto found = data_.findShares(afterVault.shareMPTID))
+            return found;
+        auto const sleShares = view.read(keylet::mptIssuance(afterVault.shareMPTID));
+        return sleShares ? std::optional<VaultInvariantData::Shares>(
+                               VaultInvariantData::Shares::make(*sleShares))
+                         : std::nullopt;
+    }();
+
+    static constexpr Number kZero{};
+
+    if (afterVault.assetsAvailable != kZero || afterVault.assetsTotal != kZero ||
+        afterVault.lossUnrealized != kZero || (updatedShares && updatedShares->sharesTotal != 0))
+    {
+        JLOG(j.fatal()) << "Invariant failed: created vault must be empty";
+        checkResult = false;
+    }
+
+    if (!updatedShares)
+    {
+        JLOG(j.fatal()) << "Invariant failed: updated vault must have shares";
+        XRPL_ASSERT(enforce, "xrpl::VaultCreate::finalizeInvariants : vault has shares invariant");
+        if (!checkResult)
+        {
+            XRPL_ASSERT(enforce, "xrpl::VaultCreate::finalizeInvariants : vault create invariants");
+        }
+        return !enforce;
+    }
+
+    if (afterVault.pseudoId != updatedShares->share.getIssuer())
+    {
+        JLOG(j.fatal())
+            << "Invariant failed: shares issuer and vault pseudo-account must be the same";
+        checkResult = false;
+    }
+
+    auto const sleSharesIssuer = view.read(keylet::account(updatedShares->share.getIssuer()));
+    if (!sleSharesIssuer)
+    {
+        JLOG(j.fatal()) << "Invariant failed: shares issuer must exist";
+        XRPL_ASSERT(
+            enforce, "xrpl::VaultCreate::finalizeInvariants : shares issuer exists invariant");
+        if (!checkResult)
+        {
+            XRPL_ASSERT(enforce, "xrpl::VaultCreate::finalizeInvariants : vault create invariants");
+        }
+        return !enforce;
+    }
+
+    if (!isPseudoAccount(sleSharesIssuer))
+    {
+        JLOG(j.fatal()) << "Invariant failed: shares issuer must be a pseudo-account";
+        checkResult = false;
+    }
+
+    if (auto const vaultId = (*sleSharesIssuer)[~sfVaultID]; !vaultId || *vaultId != afterVault.key)
+    {
+        JLOG(j.fatal())
+            << "Invariant failed: shares issuer pseudo-account must point back to the vault";
+        checkResult = false;
+    }
+
+    if (!checkResult)
+    {
+        XRPL_ASSERT(enforce, "xrpl::VaultCreate::finalizeInvariants : vault create invariants");
+        return !enforce;
+    }
+
     return true;
 }