feat: add NuDB block size tests and improve error handling

Incorporates changes from XRPLF/rippled PR #5468:

- Add getBlockSize() method to Backend interface
  Returns std::optional<std::size_t> for backends that support
  configurable block sizes (currently only NuDB)

- Update parseBlockSize() to throw exceptions instead of warnings
  Invalid block size configurations now throw std::runtime_error
  with descriptive error messages instead of silently using defaults

- Read existing database block size as default
  parseBlockSize() now checks existing nudb.key file for block size
  using nudb::block_size() before applying configuration

- Add comprehensive unit tests (NuDBFactory_test.cpp)
  Tests cover default sizes, valid sizes (4K-32K power-of-2),
  invalid sizes, error messages, power-of-2 validation, and
  data persistence across different block sizes

These changes improve configurability and error reporting while
maintaining backward compatibility.

Builds/CMake/RippledCore.cmake

@@ -457,6 +457,7 @@ target_sources (rippled PRIVATE
   src/ripple/app/tx/impl/CreateCheck.cpp
   src/ripple/app/tx/impl/CreateOffer.cpp
   src/ripple/app/tx/impl/CreateTicket.cpp
+  src/ripple/app/tx/impl/Cron.cpp
   src/ripple/app/tx/impl/DeleteAccount.cpp
   src/ripple/app/tx/impl/DepositPreauth.cpp
   src/ripple/app/tx/impl/Escrow.cpp
@@ -474,6 +475,7 @@ target_sources (rippled PRIVATE
   src/ripple/app/tx/impl/Payment.cpp
   src/ripple/app/tx/impl/Remit.cpp
   src/ripple/app/tx/impl/SetAccount.cpp
+  src/ripple/app/tx/impl/SetCron.cpp
   src/ripple/app/tx/impl/SetHook.cpp
   src/ripple/app/tx/impl/SetRemarks.cpp
   src/ripple/app/tx/impl/SetRegularKey.cpp
@@ -734,6 +736,7 @@ if (tests)
     src/test/app/BaseFee_test.cpp
     src/test/app/Check_test.cpp
     src/test/app/ClaimReward_test.cpp
+    src/test/app/Cron_test.cpp
     src/test/app/Clawback_test.cpp
     src/test/app/CrossingLimits_test.cpp
     src/test/app/DeliverMin_test.cpp
@@ -898,6 +901,7 @@ if (tests)
     src/test/jtx/impl/amount.cpp
     src/test/jtx/impl/balance.cpp
     src/test/jtx/impl/check.cpp
+    src/test/jtx/impl/cron.cpp
     src/test/jtx/impl/delivermin.cpp
     src/test/jtx/impl/deposit.cpp
     src/test/jtx/impl/envconfig.cpp
@@ -961,6 +965,7 @@ if (tests)
     src/test/nodestore/Basics_test.cpp
     src/test/nodestore/DatabaseShard_test.cpp
     src/test/nodestore/Database_test.cpp
+    src/test/nodestore/NuDBFactory_test.cpp
     src/test/nodestore/Timing_test.cpp
     src/test/nodestore/import_test.cpp
     src/test/nodestore/varint_test.cpp

CONTRIBUTING.md

@@ -176,10 +176,11 @@ existing maintainer without a vote.
 
 ## Current Maintainers
 
-* [Richard Holland](https://github.com/RichardAH) (XRPL Labs + XRP Ledger Foundation)
-* [Denis Angell](https://github.com/dangell7) (XRPL Labs + XRP Ledger Foundation)
-* [Wietse Wind](https://github.com/WietseWind) (XRPL Labs + XRP Ledger Foundation)
+* [Richard Holland](https://github.com/RichardAH) (XRPL Labs + INFTF)
+* [Denis Angell](https://github.com/dangell7) (XRPL Labs + INFTF)
+* [Wietse Wind](https://github.com/WietseWind) (XRPL Labs + INFTF)
+* [tequ](https://github.com/tequdev) (Independent + INFTF)
 
 
 [1]: https://docs.github.com/en/get-started/quickstart/contributing-to-projects
-[2]: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/incorporating-changes-from-a-pull-request/about-pull-request-merges#squash-and-merge-your-commits
+[2]: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/incorporating-changes-from-a-pull-request/about-pull-request-merges#squash-and-merge-your-commits

cfg/xahaud-example.cfg

@@ -1127,6 +1127,39 @@
 #                           it must be defined with the same value in both
 #                           sections.
 #
+#   Optional keys for NuDB only:
+#
+#       nudb_block_size     EXPERIMENTAL: Block size in bytes for NuDB storage.
+#                           Must be a power of 2 between 4096 and 32768. Default is 4096.
+#
+#                           This parameter controls the fundamental storage unit
+#                           size for NuDB's internal data structures. The choice
+#                           of block size can significantly impact performance
+#                           depending on your storage hardware and filesystem:
+#
+#                           - 4096 bytes: Optimal for most standard SSDs and
+#                             traditional filesystems (ext4, NTFS, HFS+).
+#                             Provides good balance of performance and storage
+#                             efficiency. Recommended for most deployments.
+#
+#                           - 8192-16384 bytes: May improve performance on
+#                             high-end NVMe SSDs and copy-on-write filesystems
+#                             like ZFS or Btrfs that benefit from larger block
+#                             alignment. Can reduce metadata overhead for large
+#                             databases.
+#
+#                           - 32768 bytes (32K): Maximum supported block size
+#                             for high-performance scenarios with very fast
+#                             storage. May increase memory usage and reduce
+#                             efficiency for smaller databases.
+#
+#                           Note: This setting cannot be changed after database
+#                           creation without rebuilding the entire database.
+#                           Choose carefully based on your hardware and expected
+#                           database size.
+#
+#                           Example: nudb_block_size=4096
+#
 
 #       These keys modify the behavior of online_delete, and thus are only
 #       relevant if online_delete is defined and non-zero:

hook/sfcodes.h

@@ -62,6 +62,9 @@
 #define sfEmitGeneration ((2U << 16U) + 46U)
 #define sfLockCount ((2U << 16U) + 49U)
 #define sfFirstNFTokenSequence ((2U << 16U) + 50U)
+#define sfStartTime ((2U << 16U) + 93U)
+#define sfRepeatCount ((2U << 16U) + 94U)
+#define sfDelaySeconds ((2U << 16U) + 95U)
 #define sfXahauActivationLgrSeq ((2U << 16U) + 96U)
 #define sfImportSequence ((2U << 16U) + 97U)
 #define sfRewardTime ((2U << 16U) + 98U)
@@ -129,6 +132,7 @@
 #define sfGovernanceFlags ((5U << 16U) + 99U)
 #define sfGovernanceMarks ((5U << 16U) + 98U)
 #define sfEmittedTxnID ((5U << 16U) + 97U)
+#define sfCron ((5U << 16U) + 95U)
 #define sfAmount ((6U << 16U) + 1U)
 #define sfBalance ((6U << 16U) + 2U)
 #define sfLimitAmount ((6U << 16U) + 3U)
@@ -236,4 +240,4 @@
 #define sfActiveValidators ((15U << 16U) + 95U)
 #define sfImportVLKeys ((15U << 16U) + 94U)
 #define sfHookEmissions ((15U << 16U) + 93U)
-#define sfAmounts ((15U << 16U) + 92U)
+#define sfAmounts ((15U << 16U) + 92U)

hook/tts.h

@@ -31,6 +31,8 @@
 #define ttURITOKEN_BUY 47
 #define ttURITOKEN_CREATE_SELL_OFFER 48
 #define ttURITOKEN_CANCEL_SELL_OFFER 49
+#define ttCRON 92
+#define ttCRON_SET 93
 #define ttREMIT 95
 #define ttGENESIS_MINT 96
 #define ttIMPORT 97
@@ -40,4 +42,4 @@
 #define ttFEE 101
 #define ttUNL_MODIFY 102
 #define ttEMIT_FAILURE 103
-#define ttUNL_REPORT 104
+#define ttUNL_REPORT 104

src/ripple/app/hook/impl/applyHook.cpp

@@ -75,6 +75,11 @@ getTransactionalStakeHolders(STTx const& tx, ReadView const& rv)
 
     switch (tt)
     {
+        case ttCRON: {
+            ADD_TSH(tx.getAccountID(sfOwner), tshWEAK);
+            break;
+        }
+
         case ttREMIT: {
             if (destAcc)
                 ADD_TSH(*destAcc, tshSTRONG);

src/ripple/app/misc/impl/TxQ.cpp

@@ -1477,6 +1477,64 @@ TxQ::accept(Application& app, OpenView& view)
         }
     }
 
+    // Inject cron transactions, if any
+    if (view.rules().enabled(featureCron))
+    {
+        uint32_t currentTime =
+            view.parentCloseTime().time_since_epoch().count();
+        uint256 klStart = keylet::cron(0, AccountID(beast::zero)).key;
+        uint256 const klEnd =
+            keylet::cron(currentTime + 1, AccountID(beast::zero)).key;
+
+        std::set<AccountID> cronAccs;
+
+        auto counter = 0;
+        // include max 128 cron txns in the ledger
+        while (++counter < 129 && klStart < klEnd)
+        {
+            std::optional<uint256 const> next = view.succ(klStart, klEnd);
+            if (!next.has_value())
+                break;
+
+            Keylet kl{ltANY, *next};
+
+            if (view.exists(kl))
+            {
+                auto sle = view.read(kl);
+                if (safe_cast<LedgerEntryType>(
+                        sle->getFieldU16(sfLedgerEntryType)) == ltCRON)
+                {
+                    // valid cron object, add it to the list
+                    cronAccs.emplace(sle->getAccountID(sfOwner));
+                }
+            }
+
+            klStart = *next;
+        }
+
+        auto const seq = view.info().seq;
+
+        // insert Cron pseudos for each of the accs we need to ping
+        for (AccountID const& id : cronAccs)
+        {
+            STTx cronTx(ttCRON, [=](auto& obj) {
+                obj[sfAccount] = AccountID();
+                obj[sfLedgerSequence] = seq;
+                obj[sfOwner] = id;
+            });
+
+            uint256 txID = cronTx.getTransactionID();
+
+            auto s = std::make_shared<ripple::Serializer>();
+            cronTx.add(*s);
+
+            app.getHashRouter().setFlags(txID, SF_PRIVATE2);
+            app.getHashRouter().setFlags(txID, SF_EMITTED);
+            view.rawTxInsert(txID, std::move(s), nullptr);
+            ledgerChanged = true;
+        }
+    }
+
     // Inject emitted transactions if any
     if (view.rules().enabled(featureHooks))
         do

src/ripple/app/tx/impl/Change.cpp

@@ -94,21 +94,6 @@ Change::preflight(PreflightContext const& ctx)
                                   "of sfImportVLKey, sfActiveValidator";
             return temMALFORMED;
         }
-
-        // if we do specify import_vl_keys in config then we won't approve keys
-        // that aren't on our list
-        if (ctx.tx.isFieldPresent(sfImportVLKey) &&
-            !ctx.app.config().IMPORT_VL_KEYS.empty())
-        {
-            auto const& inner = const_cast<ripple::STTx&>(ctx.tx)
-                                    .getField(sfImportVLKey)
-                                    .downcast<STObject>();
-            auto const pk = inner.getFieldVL(sfPublicKey);
-            std::string const strPk = strHex(makeSlice(pk));
-            if (ctx.app.config().IMPORT_VL_KEYS.find(strPk) ==
-                ctx.app.config().IMPORT_VL_KEYS.end())
-                return telIMPORT_VL_KEY_NOT_RECOGNISED;
-        }
     }
 
     return tesSUCCESS;
@@ -168,9 +153,42 @@ Change::preclaim(PreclaimContext const& ctx)
             return tesSUCCESS;
         case ttAMENDMENT:
         case ttUNL_MODIFY:
-        case ttUNL_REPORT:
         case ttEMIT_FAILURE:
             return tesSUCCESS;
+        case ttUNL_REPORT: {
+            if (!ctx.tx.isFieldPresent(sfImportVLKey) ||
+                ctx.app.config().IMPORT_VL_KEYS.empty())
+                return tesSUCCESS;
+
+            // if we do specify import_vl_keys in config then we won't approve
+            // keys that aren't on our list and/or aren't in the ledger object
+            auto const& inner = const_cast<ripple::STTx&>(ctx.tx)
+                                    .getField(sfImportVLKey)
+                                    .downcast<STObject>();
+            auto const pkBlob = inner.getFieldVL(sfPublicKey);
+            std::string const strPk = strHex(makeSlice(pkBlob));
+            if (ctx.app.config().IMPORT_VL_KEYS.find(strPk) !=
+                ctx.app.config().IMPORT_VL_KEYS.end())
+                return tesSUCCESS;
+
+            auto const pkType = publicKeyType(makeSlice(pkBlob));
+            if (!pkType)
+                return tefINTERNAL;
+
+            PublicKey const pk(makeSlice(pkBlob));
+
+            // check on ledger
+            if (auto const unlRep = ctx.view.read(keylet::UNLReport());
+                unlRep && unlRep->isFieldPresent(sfImportVLKeys))
+            {
+                auto const& vlKeys = unlRep->getFieldArray(sfImportVLKeys);
+                for (auto const& k : vlKeys)
+                    if (PublicKey(k[sfPublicKey]) == pk)
+                        return tesSUCCESS;
+            }
+
+            return telIMPORT_VL_KEY_NOT_RECOGNISED;
+        }
         default:
             return temUNKNOWN;
     }

src/ripple/app/tx/impl/Cron.cpp

@@ -0,0 +1,189 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of rippled: https://github.com/ripple/rippled
+    Copyright (c) 2024 XRPL-Labs
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include <ripple/app/tx/impl/Cron.h>
+#include <ripple/basics/Log.h>
+#include <ripple/core/Config.h>
+#include <ripple/ledger/View.h>
+#include <ripple/protocol/Feature.h>
+#include <ripple/protocol/Indexes.h>
+#include <ripple/protocol/PublicKey.h>
+#include <ripple/protocol/Quality.h>
+#include <ripple/protocol/TxFlags.h>
+#include <ripple/protocol/st.h>
+
+namespace ripple {
+
+TxConsequences
+Cron::makeTxConsequences(PreflightContext const& ctx)
+{
+    return TxConsequences{ctx.tx, TxConsequences::normal};
+}
+
+NotTEC
+Cron::preflight(PreflightContext const& ctx)
+{
+    if (!ctx.rules.enabled(featureCron))
+        return temDISABLED;
+
+    auto const ret = preflight0(ctx);
+    if (!isTesSuccess(ret))
+        return ret;
+
+    auto account = ctx.tx.getAccountID(sfAccount);
+    if (account != beast::zero)
+    {
+        JLOG(ctx.j.warn()) << "Cron: Bad source id";
+        return temBAD_SRC_ACCOUNT;
+    }
+
+    // No point in going any further if the transaction fee is malformed.
+    auto const fee = ctx.tx.getFieldAmount(sfFee);
+    if (!fee.native() || fee != beast::zero)
+    {
+        JLOG(ctx.j.warn()) << "Cron: invalid fee";
+        return temBAD_FEE;
+    }
+
+    if (!ctx.tx.getSigningPubKey().empty() || !ctx.tx.getSignature().empty() ||
+        ctx.tx.isFieldPresent(sfSigners))
+    {
+        JLOG(ctx.j.warn()) << "Cron: Bad signature";
+        return temBAD_SIGNATURE;
+    }
+
+    if (ctx.tx.getFieldU32(sfSequence) != 0 ||
+        ctx.tx.isFieldPresent(sfPreviousTxnID))
+    {
+        JLOG(ctx.j.warn()) << "Cron: Bad sequence";
+        return temBAD_SEQUENCE;
+    }
+
+    return tesSUCCESS;
+}
+
+TER
+Cron::preclaim(PreclaimContext const& ctx)
+{
+    if (!ctx.view.rules().enabled(featureCron))
+        return temDISABLED;
+
+    return tesSUCCESS;
+}
+
+TER
+Cron::doApply()
+{
+    auto& view = ctx_.view();
+    auto const& tx = ctx_.tx;
+
+    AccountID const& id = tx.getAccountID(sfOwner);
+
+    auto sle = view.peek(keylet::account(id));
+    if (!sle)
+    {
+        // should never happen... but might in a race condition with acc delete
+        JLOG(j_.warn()) << "Cron: sfOwner account missing. " << id;
+        return tesSUCCESS;
+    }
+
+    if (!sle->isFieldPresent(sfCron))
+    {
+        JLOG(j_.warn()) << "Cron: sfCron missing from account " << id;
+        return tefINTERNAL;
+    }
+
+    uint256 ptr = sle->getFieldH256(sfCron);
+    Keylet klOld{ltCRON, ptr};
+    auto sleCron = view.peek(klOld);
+    if (!sleCron)
+    {
+        JLOG(j_.warn()) << "Cron: Cron object missing for account " << id;
+        return tesSUCCESS;
+    }
+
+    uint32_t delay = sleCron->getFieldU32(sfDelaySeconds);
+    uint32_t recur = sleCron->getFieldU32(sfRepeatCount);
+
+    uint32_t lastStartTime = sleCron->getFieldU32(sfStartTime);
+
+    // do all this sanity checking before we modify the ledger...
+    uint32_t afterTime = lastStartTime + delay;
+    if (afterTime < lastStartTime)
+        return tefINTERNAL;
+
+    // in all circumstances the Cron object is deleted...
+    // if there are further crons to do then a new one is created at the next
+    // time point
+
+    if (!view.dirRemove(
+            keylet::ownerDir(id), (*sleCron)[sfOwnerNode], klOld, false))
+        return tefBAD_LEDGER;
+
+    view.erase(sleCron);
+
+    if (recur == 0)
+    {
+        // already at last execution, stop here
+        adjustOwnerCount(view, sle, -1, j_);
+        sle->makeFieldAbsent(sfCron);
+        view.update(sle);
+        return tesSUCCESS;
+    }
+
+    // more executions remain, so create a new object
+
+    Keylet klCron = keylet::cron(afterTime, id);
+
+    // insert into owner dir, we don't need to check reserve because we've just
+    // deleted an object
+    auto const page =
+        view.dirInsert(keylet::ownerDir(id), klCron, describeOwnerDir(id));
+    if (!page)
+        return tecDIR_FULL;
+
+    sleCron = std::make_shared<SLE>(klCron);
+
+    sleCron->setFieldU64(sfOwnerNode, *page);
+    sleCron->setFieldU32(sfDelaySeconds, delay);
+    sleCron->setFieldU32(sfRepeatCount, recur - 1);
+    sleCron->setFieldU32(sfStartTime, afterTime);
+    sleCron->setAccountID(sfOwner, id);
+
+    sle->setFieldH256(sfCron, klCron.key);
+
+    view.insert(sleCron);
+    view.update(sle);
+
+    return tesSUCCESS;
+}
+
+void
+Cron::preCompute()
+{
+    assert(account_ == beast::zero);
+}
+
+XRPAmount
+Cron::calculateBaseFee(ReadView const& view, STTx const& tx)
+{
+    return XRPAmount{0};
+}
+
+}  // namespace ripple

src/ripple/app/tx/impl/Cron.h

@@ -0,0 +1,60 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of rippled: https://github.com/ripple/rippled
+    Copyright (c) 2024 XRPL-Labs
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#ifndef RIPPLE_TX_CRON_H_INCLUDED
+#define RIPPLE_TX_CRON_H_INCLUDED
+
+#include <ripple/app/tx/impl/Transactor.h>
+#include <ripple/basics/Log.h>
+#include <ripple/core/Config.h>
+#include <ripple/protocol/Indexes.h>
+
+namespace ripple {
+
+class Cron : public Transactor
+{
+public:
+    static constexpr ConsequencesFactoryType ConsequencesFactory{Custom};
+
+    explicit Cron(ApplyContext& ctx) : Transactor(ctx)
+    {
+    }
+
+    static XRPAmount
+    calculateBaseFee(ReadView const& view, STTx const& tx);
+
+    static TxConsequences
+    makeTxConsequences(PreflightContext const& ctx);
+
+    static NotTEC
+    preflight(PreflightContext const& ctx);
+
+    static TER
+    preclaim(PreclaimContext const&);
+
+    TER
+    doApply() override;
+
+    void
+    preCompute() override;
+};
+
+}  // namespace ripple
+
+#endif

src/ripple/app/tx/impl/InvariantCheck.cpp

@@ -491,6 +491,7 @@ LedgerEntryTypesMatch::visitEntry(
             case ltNFTOKEN_PAGE:
             case ltNFTOKEN_OFFER:
             case ltURI_TOKEN:
+            case ltCRON:
             case ltIMPORT_VLSEQ:
             case ltUNL_REPORT:
                 break;

src/ripple/app/tx/impl/SetCron.cpp

@@ -0,0 +1,305 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of rippled: https://github.com/ripple/rippled
+    Copyright (c) 2024 XRPL-Labs
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include <ripple/app/tx/impl/SetCron.h>
+#include <ripple/basics/Log.h>
+#include <ripple/ledger/View.h>
+#include <ripple/protocol/Feature.h>
+#include <ripple/protocol/Indexes.h>
+#include <ripple/protocol/TxFlags.h>
+#include <ripple/protocol/st.h>
+
+namespace ripple {
+
+TxConsequences
+SetCron::makeTxConsequences(PreflightContext const& ctx)
+{
+    return TxConsequences{ctx.tx, TxConsequences::normal};
+}
+
+NotTEC
+SetCron::preflight(PreflightContext const& ctx)
+{
+    if (!ctx.rules.enabled(featureCron))
+        return temDISABLED;
+
+    if (auto const ret = preflight1(ctx); !isTesSuccess(ret))
+        return ret;
+
+    auto& tx = ctx.tx;
+    auto& j = ctx.j;
+
+    if (tx.getFlags() & tfCronSetMask)
+    {
+        JLOG(j.warn()) << "SetCron: Invalid flags set.";
+        return temINVALID_FLAG;
+    }
+
+    // DelaySeconds (D), RepeatCount (R), StartTime (S)
+    // DRS - Set Cron with Delay and Repeat and StartTime
+    // DR- - Invalid(StartTime is required)
+    // D-S - Invalid (both DelaySeconds and RepeatCount are required)
+    // -RS - Invalid (both DelaySeconds and RepeatCount are required)
+    // --S - Onetime cron with StartTime only
+    // -- - Clear any existing cron (succeeds even if there isn't one) / with
+    // tfCronUnset flag set
+
+    bool const hasDelay = tx.isFieldPresent(sfDelaySeconds);
+    bool const hasRepeat = tx.isFieldPresent(sfRepeatCount);
+    bool const hasStartTime = tx.isFieldPresent(sfStartTime);
+
+    if (tx.isFlag(tfCronUnset))
+    {
+        // delete operation
+        if (hasDelay || hasRepeat || hasStartTime)
+        {
+            JLOG(j.debug()) << "SetCron: tfCronUnset flag cannot be used with "
+                               "DelaySeconds, RepeatCount or StartTime.";
+            return temMALFORMED;
+        }
+    }
+    else
+    {
+        // create operation
+
+        if (!hasStartTime)
+        {
+            JLOG(j.debug())
+                << "SetCron: StartTime is required. Use StartTime=0 for "
+                   "immediate execution, or specify a future timestamp.";
+            return temMALFORMED;
+        }
+
+        if ((!hasDelay && hasRepeat) || (hasDelay && !hasRepeat))
+        {
+            JLOG(j.debug())
+                << "SetCron: DelaySeconds and RepeatCount must both be present "
+                   "for recurring crons, or both absent for one-off crons.";
+            return temMALFORMED;
+        }
+
+        // check delay is not too high
+        if (hasDelay)
+        {
+            auto delay = tx.getFieldU32(sfDelaySeconds);
+            if (delay > 31536000UL /* 365 days in seconds */)
+            {
+                JLOG(j.debug())
+                    << "SetCron: DelaySeconds was too high. (max 365 "
+                       "days in seconds).";
+                return temMALFORMED;
+            }
+        }
+
+        // check repeat is not too high
+        if (hasRepeat)
+        {
+            auto recur = tx.getFieldU32(sfRepeatCount);
+            if (recur == 0)
+            {
+                JLOG(j.debug())
+                    << "SetCron: RepeatCount must be greater than 0."
+                       "For one-time execution, omit DelaySeconds and "
+                       "RepeatCount.";
+                return temMALFORMED;
+            }
+            if (recur > 256)
+            {
+                JLOG(j.debug())
+                    << "SetCron: RepeatCount too high. Limit is 256. Issue "
+                       "new SetCron to increase.";
+                return temMALFORMED;
+            }
+        }
+    }
+
+    return preflight2(ctx);
+}
+
+TER
+SetCron::preclaim(PreclaimContext const& ctx)
+{
+    if (ctx.tx.isFieldPresent(sfStartTime) &&
+        ctx.tx.getFieldU32(sfStartTime) != 0)
+    {
+        // StartTime 0 means the cron will execute immediately
+
+        auto const startTime = ctx.tx.getFieldU32(sfStartTime);
+        auto const parentCloseTime =
+            ctx.view.parentCloseTime().time_since_epoch().count();
+
+        if (startTime < parentCloseTime)
+        {
+            JLOG(ctx.j.debug()) << "SetCron: StartTime must be in the future "
+                                   "(or 0 for immediate execution)";
+            return tecEXPIRED;
+        }
+
+        if (startTime > ctx.view.parentCloseTime().time_since_epoch().count() +
+                365 * 24 * 60 * 60)
+        {
+            JLOG(ctx.j.debug()) << "SetCron: StartTime is too far in the "
+                                   "future (max 365 days).";
+            return tecEXPIRED;
+        }
+    }
+    return tesSUCCESS;
+}
+
+TER
+SetCron::doApply()
+{
+    auto& view = ctx_.view();
+    auto const& tx = ctx_.tx;
+
+    bool const isDelete = tx.isFlag(tfCronUnset);
+
+    // delay can be zero, in which case the cron will usually execute next
+    // ledger.
+    uint32_t delay{0};
+    uint32_t recur{0};
+    uint32_t startTime{0};
+
+    if (!isDelete)
+    {
+        if (tx.isFieldPresent(sfDelaySeconds))
+            delay = tx.getFieldU32(sfDelaySeconds);
+        if (tx.isFieldPresent(sfRepeatCount))
+            recur = tx.getFieldU32(sfRepeatCount);
+        if (tx.isFieldPresent(sfStartTime))
+        {
+            startTime = tx.getFieldU32(sfStartTime);
+            if (startTime == 0)
+                startTime = view.parentCloseTime().time_since_epoch().count();
+        }
+    }
+
+    AccountID const& id = tx.getAccountID(sfAccount);
+    auto sle = view.peek(keylet::account(id));
+    if (!sle)
+        return tefINTERNAL;
+
+    // in all cases whatsoever, this transaction will delete an existing
+    // old cron object and return the owner reserve to the owner.
+
+    if (sle->isFieldPresent(sfCron))
+    {
+        Keylet klOld{ltCRON, sle->getFieldH256(sfCron)};
+
+        auto sleCron = view.peek(klOld);
+        if (!sleCron)
+        {
+            JLOG(j_.warn()) << "SetCron: Cron object didn't exist.";
+            return tefBAD_LEDGER;
+        }
+
+        if (safe_cast<LedgerEntryType>(
+                sleCron->getFieldU16(sfLedgerEntryType)) != ltCRON)
+        {
+            JLOG(j_.warn()) << "SetCron: sfCron pointed to non-cron object!!";
+            return tefBAD_LEDGER;
+        }
+
+        if (!view.dirRemove(
+                keylet::ownerDir(id), (*sleCron)[sfOwnerNode], klOld, false))
+        {
+            JLOG(j_.warn()) << "SetCron: Ownerdir bad. " << id;
+            return tefBAD_LEDGER;
+        }
+
+        view.erase(sleCron);
+        adjustOwnerCount(view, sle, -1, j_);
+        sle->makeFieldAbsent(sfCron);
+    }
+
+    // if the operation is a delete (no delay or recur specified then stop
+    // here.)
+    if (isDelete)
+    {
+        view.update(sle);
+        return tesSUCCESS;
+    }
+
+    // execution to here means we're creating a new Cron object and adding it to
+    // the user's owner dir
+
+    Keylet klCron = keylet::cron(startTime, id);
+
+    std::shared_ptr<SLE> sleCron = std::make_shared<SLE>(klCron);
+
+    STAmount const reserve{
+        view.fees().accountReserve(sle->getFieldU32(sfOwnerCount) + 1)};
+
+    STAmount const afterFee =
+        mPriorBalance - ctx_.tx.getFieldAmount(sfFee).xrp();
+
+    if (afterFee > mPriorBalance || afterFee < reserve)
+        return tecINSUFFICIENT_RESERVE;
+
+    // add to owner dir
+    auto const page =
+        view.dirInsert(keylet::ownerDir(id), klCron, describeOwnerDir(id));
+    if (!page)
+        return tecDIR_FULL;
+
+    sleCron->setFieldU64(sfOwnerNode, *page);
+
+    adjustOwnerCount(view, sle, 1, j_);
+
+    // set the fields
+    sleCron->setFieldU32(sfStartTime, startTime);
+    sleCron->setFieldU32(sfDelaySeconds, delay);
+    sleCron->setFieldU32(sfRepeatCount, recur);
+    sleCron->setAccountID(sfOwner, id);
+
+    sle->setFieldH256(sfCron, klCron.key);
+
+    view.update(sle);
+
+    view.insert(sleCron);
+
+    return tesSUCCESS;
+}
+
+XRPAmount
+SetCron::calculateBaseFee(ReadView const& view, STTx const& tx)
+{
+    auto const baseFee = Transactor::calculateBaseFee(view, tx);
+
+    if (tx.isFlag(tfCronUnset))
+        // delete cron
+        return baseFee;
+
+    auto const repeatCount =
+        tx.isFieldPresent(sfRepeatCount) ? tx.getFieldU32(sfRepeatCount) : 0;
+
+    // factor a cost based on the total number of txns expected
+    // for RepeatCount of 0 we have this txn (SetCron) and the
+    // single Cron txn (2). For a RepeatCount of 1 we have this txn,
+    // the first time the cron executes, and the second time (3).
+    uint32_t const additionalExpectedExecutions = 1 + repeatCount;
+    auto const additionalFee = baseFee * additionalExpectedExecutions;
+
+    if (baseFee + additionalFee < baseFee)
+        return baseFee;
+
+    return baseFee + additionalFee;
+}
+
+}  // namespace ripple

src/ripple/app/tx/impl/SetCron.h

@@ -0,0 +1,56 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of rippled: https://github.com/ripple/rippled
+    Copyright (c) 2024 XRPL-Labs
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#ifndef RIPPLE_TX_SETCRON_H_INCLUDED
+#define RIPPLE_TX_SETCRON_H_INCLUDED
+
+#include <ripple/app/tx/impl/Transactor.h>
+#include <ripple/basics/Log.h>
+#include <ripple/protocol/Indexes.h>
+
+namespace ripple {
+
+class SetCron : public Transactor
+{
+public:
+    static constexpr ConsequencesFactoryType ConsequencesFactory{Custom};
+
+    explicit SetCron(ApplyContext& ctx) : Transactor(ctx)
+    {
+    }
+
+    static XRPAmount
+    calculateBaseFee(ReadView const& view, STTx const& tx);
+
+    static TxConsequences
+    makeTxConsequences(PreflightContext const& ctx);
+
+    static NotTEC
+    preflight(PreflightContext const& ctx);
+
+    static TER
+    preclaim(PreclaimContext const&);
+
+    TER
+    doApply() override;
+};
+
+}  // namespace ripple
+
+#endif

src/ripple/app/tx/impl/applySteps.cpp

@@ -28,6 +28,7 @@
 #include <ripple/app/tx/impl/CreateCheck.h>
 #include <ripple/app/tx/impl/CreateOffer.h>
 #include <ripple/app/tx/impl/CreateTicket.h>
+#include <ripple/app/tx/impl/Cron.h>
 #include <ripple/app/tx/impl/DeleteAccount.h>
 #include <ripple/app/tx/impl/DepositPreauth.h>
 #include <ripple/app/tx/impl/Escrow.h>
@@ -43,6 +44,7 @@
 #include <ripple/app/tx/impl/Payment.h>
 #include <ripple/app/tx/impl/Remit.h>
 #include <ripple/app/tx/impl/SetAccount.h>
+#include <ripple/app/tx/impl/SetCron.h>
 #include <ripple/app/tx/impl/SetHook.h>
 #include <ripple/app/tx/impl/SetRegularKey.h>
 #include <ripple/app/tx/impl/SetRemarks.h>
@@ -181,6 +183,10 @@ invoke_preflight(PreflightContext const& ctx)
         case ttURITOKEN_CREATE_SELL_OFFER:
         case ttURITOKEN_CANCEL_SELL_OFFER:
             return invoke_preflight_helper<URIToken>(ctx);
+        case ttCRON_SET:
+            return invoke_preflight_helper<SetCron>(ctx);
+        case ttCRON:
+            return invoke_preflight_helper<Cron>(ctx);
         default:
             assert(false);
             return {temUNKNOWN, TxConsequences{temUNKNOWN}};
@@ -306,6 +312,10 @@ invoke_preclaim(PreclaimContext const& ctx)
         case ttURITOKEN_CREATE_SELL_OFFER:
         case ttURITOKEN_CANCEL_SELL_OFFER:
             return invoke_preclaim<URIToken>(ctx);
+        case ttCRON_SET:
+            return invoke_preclaim<SetCron>(ctx);
+        case ttCRON:
+            return invoke_preclaim<Cron>(ctx);
         default:
             assert(false);
             return temUNKNOWN;
@@ -393,6 +403,10 @@ invoke_calculateBaseFee(ReadView const& view, STTx const& tx)
         case ttURITOKEN_CREATE_SELL_OFFER:
         case ttURITOKEN_CANCEL_SELL_OFFER:
             return URIToken::calculateBaseFee(view, tx);
+        case ttCRON_SET:
+            return SetCron::calculateBaseFee(view, tx);
+        case ttCRON:
+            return Cron::calculateBaseFee(view, tx);
         default:
             return XRPAmount{0};
     }
@@ -586,6 +600,14 @@ invoke_apply(ApplyContext& ctx)
             URIToken p(ctx);
             return p();
         }
+        case ttCRON_SET: {
+            SetCron p(ctx);
+            return p();
+        }
+        case ttCRON: {
+            Cron p(ctx);
+            return p();
+        }
         default:
             assert(false);
             return {temUNKNOWN, false};

src/ripple/nodestore/Backend.h

@@ -23,6 +23,7 @@
 #include <ripple/nodestore/Types.h>
 #include <atomic>
 #include <cstdint>
+#include <optional>
 
 namespace ripple {
 namespace NodeStore {
@@ -175,6 +176,14 @@ public:
     virtual int
     fdRequired() const = 0;
 
+    /** Get the block size for backends that support it
+     */
+    virtual std::optional<std::size_t>
+    getBlockSize() const
+    {
+        return std::nullopt;
+    }
+
     /** Returns read and write stats.
 
         @note The Counters struct is specific to and only used

src/ripple/nodestore/backend/NuDBFactory.cpp

@@ -18,6 +18,7 @@
 //==============================================================================
 
 #include <ripple/basics/contract.h>
+#include <ripple/beast/core/LexicalCast.h>
 #include <ripple/nodestore/Factory.h>
 #include <ripple/nodestore/Manager.h>
 #include <ripple/nodestore/impl/DecodedBlob.h>
@@ -31,6 +32,7 @@
 #include <exception>
 #include <memory>
 #include <nudb/nudb.hpp>
+#include <sstream>
 
 namespace ripple {
 namespace NodeStore {
@@ -48,6 +50,7 @@ public:
     size_t const keyBytes_;
     std::size_t const burstSize_;
     std::string const name_;
+    std::size_t const blockSize_;
     nudb::store db_;
     std::atomic<bool> deletePath_;
     Scheduler& scheduler_;
@@ -62,6 +65,7 @@ public:
         , keyBytes_(keyBytes)
         , burstSize_(burstSize)
         , name_(get(keyValues, "path"))
+        , blockSize_(parseBlockSize(name_, keyValues, journal))
         , deletePath_(false)
         , scheduler_(scheduler)
     {
@@ -81,6 +85,7 @@ public:
         , keyBytes_(keyBytes)
         , burstSize_(burstSize)
         , name_(get(keyValues, "path"))
+        , blockSize_(parseBlockSize(name_, keyValues, journal))
         , db_(context)
         , deletePath_(false)
         , scheduler_(scheduler)
@@ -110,6 +115,12 @@ public:
         return name_;
     }
 
+    std::optional<std::size_t>
+    getBlockSize() const override
+    {
+        return blockSize_;
+    }
+
     void
     open(bool createIfMissing, uint64_t appType, uint64_t uid, uint64_t salt)
         override
@@ -137,7 +148,7 @@ public:
                 uid,
                 salt,
                 keyBytes_,
-                nudb::block_size(kp),
+                blockSize_,
                 0.50,
                 ec);
             if (ec == nudb::errc::file_exists)
@@ -362,6 +373,56 @@ public:
     {
         return 3;
     }
+
+private:
+    static std::size_t
+    parseBlockSize(
+        std::string const& name,
+        Section const& keyValues,
+        beast::Journal journal)
+    {
+        using namespace boost::filesystem;
+        auto const folder = path(name);
+        auto const kp = (folder / "nudb.key").string();
+
+        std::size_t const defaultSize =
+            nudb::block_size(kp);  // Default 4K from NuDB
+        std::size_t blockSize = defaultSize;
+        std::string blockSizeStr;
+
+        if (!get_if_exists(keyValues, "nudb_block_size", blockSizeStr))
+        {
+            return blockSize;  // Early return with default
+        }
+
+        try
+        {
+            std::size_t const parsedBlockSize =
+                beast::lexicalCastThrow<std::size_t>(blockSizeStr);
+
+            // Validate: must be power of 2 between 4K and 32K
+            if (parsedBlockSize < 4096 || parsedBlockSize > 32768 ||
+                (parsedBlockSize & (parsedBlockSize - 1)) != 0)
+            {
+                std::stringstream s;
+                s << "Invalid nudb_block_size: " << parsedBlockSize
+                  << ". Must be power of 2 between 4096 and 32768.";
+                Throw<std::runtime_error>(s.str());
+            }
+
+            JLOG(journal.info())
+                << "Using custom NuDB block size: " << parsedBlockSize
+                << " bytes";
+            return parsedBlockSize;
+        }
+        catch (std::exception const& e)
+        {
+            std::stringstream s;
+            s << "Invalid nudb_block_size value: " << blockSizeStr
+              << ". Error: " << e.what();
+            Throw<std::runtime_error>(s.str());
+        }
+    }
 };
 
 //------------------------------------------------------------------------------

src/ripple/protocol/Feature.h

@@ -74,7 +74,7 @@ namespace detail {
 // Feature.cpp. Because it's only used to reserve storage, and determine how
 // large to make the FeatureBitset, it MAY be larger. It MUST NOT be less than
 // the actual number of amendments. A LogicError on startup will verify this.
-static constexpr std::size_t numFeatures = 86;
+static constexpr std::size_t numFeatures = 87;
 
 /** Amendments that this server supports and the default voting behavior.
    Whether they are enabled depends on the Rules defined in the validated
@@ -373,6 +373,7 @@ extern uint256 const fixProvisionalDoubleThreading;
 extern uint256 const featureClawback;
 extern uint256 const featureDeepFreeze;
 extern uint256 const featureIOUIssuerWeakTSH;
+extern uint256 const featureCron;
 extern uint256 const fixInvalidTxFlags;
 
 }  // namespace ripple

src/ripple/protocol/Indexes.h

@@ -297,6 +297,9 @@ import_vlseq(PublicKey const& key) noexcept;
 Keylet
 uritoken(AccountID const& issuer, Blob const& uri);
 
+Keylet
+cron(uint32_t timestamp, AccountID const& id);
+
 }  // namespace keylet
 
 // Everything below is deprecated and should be removed in favor of keylets:

src/ripple/protocol/LedgerFormats.h

@@ -58,6 +58,12 @@ enum LedgerEntryType : std::uint16_t
      */
     ltACCOUNT_ROOT = 0x0061,
 
+    /** A ledger object representing a scheduled cron execution on an account.
+     
+        \sa keylet::cron
+    */
+    ltCRON = 0x0041,
+
     /** A ledger object which contains a list of object identifiers.
 
         \sa keylet::page, keylet::quality, keylet::book, keylet::next and

src/ripple/protocol/SField.h

@@ -410,6 +410,9 @@ extern SF_UINT32 const sfRewardLgrLast;
 extern SF_UINT32 const sfFirstNFTokenSequence;
 extern SF_UINT32 const sfImportSequence;
 extern SF_UINT32 const sfXahauActivationLgrSeq;
+extern SF_UINT32 const sfDelaySeconds;
+extern SF_UINT32 const sfRepeatCount;
+extern SF_UINT32 const sfStartTime;
 
 // 64-bit integers (common)
 extern SF_UINT64 const sfIndexNext;
@@ -486,6 +489,7 @@ extern SF_UINT256 const sfURITokenID;
 extern SF_UINT256 const sfGovernanceFlags;
 extern SF_UINT256 const sfGovernanceMarks;
 extern SF_UINT256 const sfEmittedTxnID;
+extern SF_UINT256 const sfCron;
 
 // currency amount (common)
 extern SF_AMOUNT const sfAmount;

src/ripple/protocol/TxFlags.h

@@ -200,6 +200,12 @@ constexpr std::uint32_t const tfImmutable = 1;
 // Clawback flags:
 constexpr std::uint32_t const tfClawbackMask = ~tfUniversal;
 
+// CronSet Flags:
+enum CronSetFlags : uint32_t {
+    tfCronUnset = 0x00000001,
+};
+constexpr std::uint32_t const tfCronSetMask = ~(tfUniversal | tfCronUnset);
+
 // clang-format on
 
 }  // namespace ripple

src/ripple/protocol/TxFormats.h

@@ -149,6 +149,12 @@ enum TxType : std::uint16_t
     ttURITOKEN_CREATE_SELL_OFFER = 48,
     ttURITOKEN_CANCEL_SELL_OFFER = 49,
 
+    /* A pseudo-txn alarm signal for invoking a hook, emitted by validators after alarm set conditions are met */
+    ttCRON = 92,
+
+    /* Sechedule an alarm for later */
+    ttCRON_SET = 93,
+
     /* A note attaching transactor that allows the owner or issuer (on a object by object basis) to attach remarks */
     ttREMARKS_SET = 94,
 

src/ripple/protocol/impl/Feature.cpp

@@ -479,6 +479,7 @@ REGISTER_FEATURE(Clawback,                      Supported::yes, VoteBehavior::De
 REGISTER_FIX    (fixProvisionalDoubleThreading, Supported::yes, VoteBehavior::DefaultYes);
 REGISTER_FEATURE(DeepFreeze,                    Supported::yes, VoteBehavior::DefaultNo);
 REGISTER_FEATURE(IOUIssuerWeakTSH,              Supported::yes, VoteBehavior::DefaultNo);
+REGISTER_FEATURE(Cron,                          Supported::yes, VoteBehavior::DefaultNo);
 REGISTER_FIX    (fixInvalidTxFlags,             Supported::yes, VoteBehavior::DefaultYes);
 
 // The following amendments are obsolete, but must remain supported

src/ripple/protocol/impl/Indexes.cpp

@@ -72,6 +72,7 @@ enum class LedgerNameSpace : std::uint16_t {
     URI_TOKEN = 'U',
     IMPORT_VLSEQ = 'I',
     UNL_REPORT = 'R',
+    CRON = 'A',
 
     // No longer used or supported. Left here to reserve the space
     // to avoid accidental reuse.
@@ -443,6 +444,51 @@ uritoken(AccountID const& issuer, Blob const& uri)
             LedgerNameSpace::URI_TOKEN, issuer, Slice{uri.data(), uri.size()})};
 }
 
+// Constructs an ordered CRON keylet (32 bytes):
+//   [8-byte namespace][4-byte timestamp (big-endian, seconds)][20-byte
+//   AccountID]
+//
+// Properties
+// - Namespacing: first 8 bytes are the most-significant bytes of
+// indexHash(LedgerNameSpace::CRON).
+// - Uniqueness (per ts,acct): exactly ONE cron per (timestamp, AccountID).
+// Insert is upsert (last-write-wins).
+//   This is fine because we only ever allow one cron per account at a time—if
+//   the same (ts,acct) is written, it’s simply an update to that single entry
+//   (idempotent; no duplicate leaves).
+// - Iteration order: chronological by timestamp (BE), then by raw AccountID
+// bytes.
+//   NOTE: raw AccountID ordering may bias priority; consider hashing AccountID
+//   for uniform per-timestamp spread.
+// - Expected accidental prefix collisions (foreign objects sharing the 8-byte
+// namespace): n / 2^64,
+//   assuming uniform high-64-bit distribution of other objects.
+//   Examples: 100M → ~5.4e-12, 1B → ~5.4e-11, 10B → ~5.4e-10, 100B → ~5.4e-9
+//   (negligible).
+Keylet
+cron(uint32_t timestamp, AccountID const& id)
+{
+    static const uint256 ns = indexHash(LedgerNameSpace::CRON);
+
+    uint8_t h[32];
+
+    // first 8 bytes are the namespacing
+    std::memcpy(h, ns.data(), 8);
+
+    // next 4 bytes are the timestamp in BE
+    h[8] = static_cast<uint8_t>((timestamp >> 24) & 0xFFU);
+    h[9] = static_cast<uint8_t>((timestamp >> 16) & 0xFFU);
+    h[10] = static_cast<uint8_t>((timestamp >> 8) & 0xFFU);
+    h[11] = static_cast<uint8_t>((timestamp >> 0) & 0xFFU);
+
+    const uint256 accHash = indexHash(LedgerNameSpace::CRON, timestamp, id);
+
+    // final 20 bytes are account ID
+    std::memcpy(h + 12, accHash.cdata(), 20);
+
+    return {ltCRON, uint256::fromVoid(h)};
+}
+
 }  // namespace keylet
 
 }  // namespace ripple

src/ripple/protocol/impl/LedgerFormats.cpp

@@ -68,6 +68,7 @@ LedgerFormats::LedgerFormats()
             {sfGovernanceMarks,      soeOPTIONAL},
             {sfAccountIndex,         soeOPTIONAL},
             {sfTouchCount,           soeOPTIONAL},
+            {sfCron,                 soeOPTIONAL},
         },
         commonFields);
 
@@ -366,6 +367,17 @@ LedgerFormats::LedgerFormats()
         },
         commonFields);
 
+    add(jss::Cron,
+        ltCRON,
+        {
+            {sfOwner,                soeREQUIRED},
+            {sfStartTime,            soeREQUIRED},
+            {sfDelaySeconds,         soeREQUIRED},
+            {sfRepeatCount,          soeREQUIRED},
+            {sfOwnerNode,            soeREQUIRED},
+        },
+        commonFields);
+
     // clang-format on
 }
 

src/ripple/protocol/impl/SField.cpp

@@ -157,6 +157,9 @@ CONSTRUCT_TYPED_SFIELD(sfLockCount,             "LockCount",            UINT32,
 
 CONSTRUCT_TYPED_SFIELD(sfFirstNFTokenSequence,  "FirstNFTokenSequence", UINT32,    50);
 
+CONSTRUCT_TYPED_SFIELD(sfStartTime,             "StartTime",            UINT32,    93);
+CONSTRUCT_TYPED_SFIELD(sfRepeatCount,           "RepeatCount",          UINT32,    94);
+CONSTRUCT_TYPED_SFIELD(sfDelaySeconds,          "DelaySeconds",         UINT32,    95);
 CONSTRUCT_TYPED_SFIELD(sfXahauActivationLgrSeq, "XahauActivationLgrSeq",UINT32,    96);
 CONSTRUCT_TYPED_SFIELD(sfImportSequence,        "ImportSequence",       UINT32,    97);
 CONSTRUCT_TYPED_SFIELD(sfRewardTime,            "RewardTime",           UINT32,    98);
@@ -239,6 +242,7 @@ CONSTRUCT_TYPED_SFIELD(sfGovernanceFlags,       "GovernanceFlags",      UINT256,
 CONSTRUCT_TYPED_SFIELD(sfGovernanceMarks,       "GovernanceMarks",      UINT256,   98);
 CONSTRUCT_TYPED_SFIELD(sfEmittedTxnID,          "EmittedTxnID",         UINT256,   97);
 CONSTRUCT_TYPED_SFIELD(sfHookCanEmit,           "HookCanEmit",          UINT256,   96);
+CONSTRUCT_TYPED_SFIELD(sfCron,                  "Cron",                 UINT256,   95);
 
 // currency amount (common)
 CONSTRUCT_TYPED_SFIELD(sfAmount,                "Amount",               AMOUNT,     1);

src/ripple/protocol/impl/STTx.cpp

@@ -615,7 +615,7 @@ isPseudoTx(STObject const& tx)
 
     auto tt = safe_cast<TxType>(*t);
     return tt == ttAMENDMENT || tt == ttFEE || tt == ttUNL_MODIFY ||
-        tt == ttEMIT_FAILURE || tt == ttUNL_REPORT;
+        tt == ttEMIT_FAILURE || tt == ttUNL_REPORT || tt == ttCRON;
 }
 
 }  // namespace ripple

src/ripple/protocol/impl/TxFormats.cpp

@@ -472,6 +472,23 @@ TxFormats::TxFormats()
             {sfTicketSequence, soeOPTIONAL},
         },
         commonFields);
+
+    add(jss::Cron,
+        ttCRON,
+        {
+            {sfOwner, soeREQUIRED},
+            {sfLedgerSequence, soeREQUIRED},
+        },
+        commonFields);
+
+    add(jss::CronSet,
+        ttCRON_SET,
+        {
+            {sfDelaySeconds, soeOPTIONAL},
+            {sfRepeatCount, soeOPTIONAL},
+            {sfStartTime, soeOPTIONAL},
+        },
+        commonFields);
 }
 
 TxFormats const&

src/ripple/protocol/jss.h

@@ -51,14 +51,16 @@ JSS(Amendments);     // ledger type.
 JSS(Amount);         // in: TransactionSign; field.
 JSS(Authorize);      // field
 JSS(Blob);
-JSS(Check);              // ledger type.
-JSS(CheckCancel);        // transaction type.
-JSS(CheckCash);          // transaction type.
-JSS(CheckCreate);        // transaction type.
-JSS(ClaimReward);        // transaction type.
-JSS(Clawback);           // transaction type.
-JSS(ClearFlag);          // field.
-JSS(CreateCode);         // field.
+JSS(Check);        // ledger type.
+JSS(CheckCancel);  // transaction type.
+JSS(CheckCash);    // transaction type.
+JSS(CheckCreate);  // transaction type.
+JSS(ClaimReward);  // transaction type.
+JSS(Clawback);     // transaction type.
+JSS(ClearFlag);    // field.
+JSS(CreateCode);   // field.
+JSS(Cron);
+JSS(CronSet);
 JSS(DeliverMin);         // in: TransactionSign
 JSS(DepositPreauth);     // transaction and ledger type.
 JSS(Destination);        // in: TransactionSign; field.

src/ripple/rpc/handlers/ServerDefinitions.cpp

@@ -423,6 +423,7 @@ private:
         addFlagsToJson<NFTokenMintFlags>(ret, "NFTokenMint");
         addFlagsToJson<NFTokenCreateOfferFlags>(ret, "NFTokenCreateOffer");
         addFlagsToJson<ClaimRewardFlags>(ret, "ClaimReward");
+        addFlagsToJson<CronSetFlags>(ret, "CronSet");
         struct FlagData
         {
             std::string name;

src/test/app/Cron_test.cpp

@@ -0,0 +1,496 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of rippled: https://github.com/ripple/rippled
+    Copyright (c) 2025 XRPL Labs
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include <ripple/app/ledger/LedgerMaster.h>
+#include <ripple/protocol/Feature.h>
+#include <ripple/protocol/jss.h>
+#include <test/jtx.h>
+
+namespace ripple {
+namespace test {
+struct Cron_test : public beast::unit_test::suite
+{
+    void
+    testEnabled(FeatureBitset features)
+    {
+        testcase("enabled");
+        using namespace jtx;
+        using namespace std::literals::chrono_literals;
+
+        // setup env
+        auto const alice = Account("alice");
+        auto const issuer = Account("issuer");
+
+        for (bool const withCron : {false, true})
+        {
+            auto const amend = withCron ? features : features - featureCron;
+            Env env{*this, amend};
+
+            env.fund(XRP(1000), alice, issuer);
+            env.close();
+
+            auto const expectResult =
+                withCron ? ter(tesSUCCESS) : ter(temDISABLED);
+
+            // CLAIM
+            env(cron::set(alice),
+                cron::startTime(0),
+                cron::repeat(100),
+                cron::delay(100),
+                fee(XRP(1)),
+                expectResult);
+            env.close();
+        }
+    }
+
+    void
+    testFee(FeatureBitset features)
+    {
+        testcase("fee");
+        using namespace jtx;
+        using namespace std::literals::chrono_literals;
+
+        auto const alice = Account("alice");
+        Env env{*this, features | featureCron};
+
+        auto const baseFee = env.current()->fees().base;
+
+        env.fund(XRP(1000), alice);
+        env.close();
+
+        // create
+        auto expected = baseFee * 2 + baseFee * 256;
+        env(cron::set(alice),
+            cron::startTime(0),
+            cron::delay(356 * 24 * 60 * 60),
+            cron::repeat(256),
+            fee(expected - 1),
+            ter(telINSUF_FEE_P));
+        env.close();
+
+        env(cron::set(alice),
+            cron::startTime(0),
+            cron::delay(356 * 24 * 60 * 60),
+            cron::repeat(256),
+            fee(expected),
+            ter(tesSUCCESS));
+        env.close();
+
+        // delete
+        expected = baseFee;
+        env(cron::set(alice),
+            txflags(tfCronUnset),
+            fee(expected - 1),
+            ter(telINSUF_FEE_P));
+        env.close();
+
+        env(cron::set(alice),
+            txflags(tfCronUnset),
+            fee(expected),
+            ter(tesSUCCESS));
+        env.close();
+    }
+
+    void
+    testInvalidPreflight(FeatureBitset features)
+    {
+        testcase("invalid preflight");
+        using namespace test::jtx;
+        using namespace std::literals;
+
+        auto const alice = Account("alice");
+
+        test::jtx::Env env{
+            *this, network::makeNetworkConfig(21337), features | featureCron};
+
+        env.fund(XRP(1000), alice);
+        env.close();
+
+        //----------------------------------------------------------------------
+        // preflight
+
+        // temINVALID_FLAG
+        {
+            env(cron::set(alice), txflags(tfClose), ter(temINVALID_FLAG));
+            env(cron::set(alice),
+                txflags(tfUniversalMask),
+                ter(temINVALID_FLAG));
+        }
+
+        // temMALFORMED
+        {
+            // Invalid DelaySeconds and RepeatCount and StartTime are not
+            // specified
+            env(cron::set(alice), ter(temMALFORMED));
+
+            // Invalid DelaySeconds and RepeatCount combination with StartTime
+            env(cron::set(alice),
+                cron::startTime(100),
+                cron::delay(356 * 24 * 60 * 60),
+                ter(temMALFORMED));
+            env(cron::set(alice),
+                cron::startTime(100),
+                cron::repeat(256),
+                ter(temMALFORMED));
+
+            // Invalid DelaySeconds
+            env(cron::set(alice),
+                cron::startTime(100),
+                cron::delay(365 * 24 * 60 * 60 + 1),
+                cron::repeat(256),
+                ter(temMALFORMED));
+
+            // Invalid RepeatCount
+            env(cron::set(alice),
+                cron::startTime(100),
+                cron::delay(365 * 24 * 60 * 60),
+                cron::repeat(257),
+                ter(temMALFORMED));
+
+            // Invalid with tfCronUnset flag
+            env(cron::set(alice),
+                cron::delay(365 * 24 * 60 * 60),
+                txflags(tfCronUnset),
+                ter(temMALFORMED));
+            env(cron::set(alice),
+                cron::repeat(100),
+                txflags(tfCronUnset),
+                ter(temMALFORMED));
+            env(cron::set(alice),
+                cron::startTime(100),
+                txflags(tfCronUnset),
+                ter(temMALFORMED));
+        }
+    }
+
+    void
+    testInvalidPreclaim(FeatureBitset features)
+    {
+        testcase("invalid preclaim");
+        using namespace test::jtx;
+        using namespace std::literals;
+
+        auto const alice = Account("alice");
+        Env env{*this, features | featureCron};
+        env.fund(XRP(1000), alice);
+        env.close();
+
+        // Past StartTime
+        env(cron::set(alice),
+            cron::startTime(
+                env.timeKeeper().now().time_since_epoch().count() - 1),
+            fee(XRP(1)),
+            ter(tecEXPIRED));
+        env.close();
+
+        // Too far Future StartTime
+        env(cron::set(alice),
+            cron::startTime(
+                env.timeKeeper().now().time_since_epoch().count() +
+                365 * 24 * 60 * 60 + 1),
+            fee(XRP(1)),
+            ter(tecEXPIRED));
+        env.close();
+    }
+
+    void
+    testDoApply(FeatureBitset features)
+    {
+        testcase("doApply");
+        using namespace jtx;
+        using namespace std::literals::chrono_literals;
+        auto const alice = Account("alice");
+        Env env{*this, features | featureCron};
+
+        env.fund(XRP(1000), alice);
+        env.close();
+
+        auto const aliceOwnerCount = ownerCount(env, alice);
+
+        // create cron
+        auto parentCloseTime =
+            env.current()->parentCloseTime().time_since_epoch().count();
+        env(cron::set(alice),
+            cron::startTime(parentCloseTime + 356 * 24 * 60 * 60),
+            cron::delay(356 * 24 * 60 * 60),
+            cron::repeat(256),
+            fee(XRP(1)),
+            ter(tesSUCCESS));
+        env.close();
+
+        // increment owner count
+        BEAST_EXPECT(ownerCount(env, alice) == aliceOwnerCount + 1);
+
+        auto const accSle = env.le(keylet::account(alice.id()));
+        BEAST_EXPECT(accSle);
+        BEAST_EXPECT(accSle->isFieldPresent(sfCron));
+
+        auto const cronKey = keylet::child(accSle->getFieldH256(sfCron));
+        auto const cronSle = env.le(cronKey);
+        BEAST_EXPECT(cronSle);
+        BEAST_EXPECT(
+            cronSle->getFieldU32(sfDelaySeconds) == 356 * 24 * 60 * 60);
+        BEAST_EXPECT(cronSle->getFieldU32(sfRepeatCount) == 256);
+        BEAST_EXPECT(
+            cronSle->getFieldU32(sfStartTime) ==
+            parentCloseTime + 356 * 24 * 60 * 60);
+
+        // update cron
+        parentCloseTime =
+            env.current()->parentCloseTime().time_since_epoch().count();
+        env(cron::set(alice),
+            cron::startTime(0),
+            cron::delay(100),
+            cron::repeat(10),
+            fee(XRP(1)),
+            ter(tesSUCCESS));
+        env.close();
+
+        // owner count does not change
+        BEAST_EXPECT(ownerCount(env, alice) == aliceOwnerCount + 1);
+
+        auto const accSle2 = env.le(keylet::account(alice.id()));
+        BEAST_EXPECT(accSle2);
+        BEAST_EXPECT(accSle2->isFieldPresent(sfCron));
+
+        // old cron sle is deleted
+        BEAST_EXPECT(!env.le(cronKey));
+
+        auto const cronKey2 = keylet::child(accSle2->getFieldH256(sfCron));
+        auto const cronSle2 = env.le(cronKey2);
+        BEAST_EXPECT(cronSle2);
+        BEAST_EXPECT(cronSle2->getFieldU32(sfDelaySeconds) == 100);
+        BEAST_EXPECT(cronSle2->getFieldU32(sfRepeatCount) == 10);
+        BEAST_EXPECT(cronSle2->getFieldU32(sfStartTime) == parentCloseTime);
+
+        // delete cron
+        env(cron::set(alice),
+            fee(XRP(1)),
+            txflags(tfCronUnset),
+            ter(tesSUCCESS));
+        env.close();
+
+        // owner count decremented
+        BEAST_EXPECT(ownerCount(env, alice) == aliceOwnerCount);
+
+        auto const accSle3 = env.le(keylet::account(alice.id()));
+        BEAST_EXPECT(accSle3);
+        BEAST_EXPECT(!accSle3->isFieldPresent(sfCron));
+
+        // old cron sle is deleted
+        BEAST_EXPECT(!env.le(cronKey2));
+
+        // delete cron without object will succeed
+        env(cron::set(alice),
+            fee(XRP(1)),
+            txflags(tfCronUnset),
+            ter(tesSUCCESS));
+        env.close();
+    }
+
+    void
+    testCronExecution(FeatureBitset features)
+    {
+        testcase("cron execution");
+        using namespace jtx;
+        using namespace std::literals::chrono_literals;
+        auto const alice = Account("alice");
+
+        {
+            // test ttCron execution and repeatCount
+            Env env{*this, features | featureCron};
+
+            env.fund(XRP(1000), alice);
+            env.close();
+
+            auto baseTime = env.timeKeeper().now().time_since_epoch().count();
+
+            auto repeatCount = 10;
+
+            env(cron::set(alice),
+                cron::startTime(baseTime + 100),
+                cron::delay(100),
+                cron::repeat(repeatCount),
+                fee(XRP(1)));
+            env.close(10s);
+
+            auto lastCronKeylet =
+                keylet::child(env.le(alice)->getFieldH256(sfCron));
+
+            while (repeatCount >= 0)
+            {
+                // close ledger until 100 seconds has passed
+                while (env.timeKeeper().now().time_since_epoch().count() -
+                           baseTime <
+                       100)
+                {
+                    env.close(10s);
+                    auto txns = env.closed()->txs;
+                    auto size = std::distance(txns.begin(), txns.end());
+                    BEAST_EXPECT(size == 0);
+                }
+
+                // close after 100 seconds passed
+                env.close(10s);
+
+                auto txns = env.closed()->txs;
+                auto size = std::distance(txns.begin(), txns.end());
+                BEAST_EXPECT(size == 1);
+                for (auto it = txns.begin(); it != txns.end(); ++it)
+                {
+                    auto const& tx = *it->first;
+                    // check pseudo txn format
+                    BEAST_EXPECT(tx.getTxnType() == ttCRON);
+                    BEAST_EXPECT(tx.getAccountID(sfAccount) == AccountID());
+                    BEAST_EXPECT(tx.getAccountID(sfOwner) == alice.id());
+                    BEAST_EXPECT(
+                        tx.getFieldU32(sfLedgerSequence) ==
+                        env.closed()->info().seq);
+                    BEAST_EXPECT(tx.getFieldAmount(sfFee) == XRP(0));
+                    BEAST_EXPECT(tx.getFieldVL(sfSigningPubKey).size() == 0);
+
+                    // check old Cron object is deleted
+                    BEAST_EXPECT(!env.le(lastCronKeylet));
+
+                    if (repeatCount > 0)
+                    {
+                        // check new Cron object
+                        auto const cronKeylet =
+                            keylet::child(env.le(alice)->getFieldH256(sfCron));
+                        auto const cronSle = env.le(cronKeylet);
+                        BEAST_EXPECT(cronSle);
+                        BEAST_EXPECT(
+                            cronSle->getFieldU32(sfDelaySeconds) == 100);
+                        BEAST_EXPECT(
+                            cronSle->getFieldU32(sfRepeatCount) ==
+                            --repeatCount);
+                        BEAST_EXPECT(
+                            cronSle->getAccountID(sfOwner) == alice.id());
+
+                        // set new base time
+                        baseTime = baseTime + 100;
+                        lastCronKeylet = cronKeylet;
+                    }
+                    else
+                    {
+                        // after all executions, the cron object should be
+                        // deleted
+                        BEAST_EXPECT(!env.le(alice)->isFieldPresent(sfCron));
+                        BEAST_EXPECT(!env.le(lastCronKeylet));
+                        --repeatCount;  // decrement for break double loop
+                    }
+                }
+            }
+        }
+
+        {
+            // test ttCron limit in a ledger
+            Env env{*this, features | featureCron};
+            std::vector<Account> accounts;
+            accounts.reserve(300);
+            for (int i = 0; i < 300; ++i)
+            {
+                auto const& account = accounts.emplace_back(
+                    Account("account_" + std::to_string(i)));
+                accounts.emplace_back(account);
+                env.fund(XRP(10000), account);
+            }
+            env.close();
+
+            for (auto const& account : accounts)
+            {
+                env(cron::set(account), cron::startTime(0), fee(XRP(1)));
+            }
+            env.close();
+
+            // proceed ledger
+            env.close();
+            {
+                auto const txns = env.closed()->txs;
+                auto size = std::distance(txns.begin(), txns.end());
+                BEAST_EXPECT(size == 128);
+                for (auto it = txns.begin(); it != txns.end(); ++it)
+                {
+                    auto const& tx = *it->first;
+                    BEAST_EXPECT(tx.getTxnType() == ttCRON);
+                }
+            }
+
+            // proceed ledger
+            env.close();
+            {
+                auto const txns = env.closed()->txs;
+                auto size = std::distance(txns.begin(), txns.end());
+                BEAST_EXPECT(size == 128);
+                for (auto it = txns.begin(); it != txns.end(); ++it)
+                {
+                    auto const& tx = *it->first;
+                    BEAST_EXPECT(tx.getTxnType() == ttCRON);
+                }
+            }
+
+            // proceed ledger
+            env.close();
+            {
+                auto const txns = env.closed()->txs;
+                auto size = std::distance(txns.begin(), txns.end());
+                BEAST_EXPECT(size == 44);
+                for (auto it = txns.begin(); it != txns.end(); ++it)
+                {
+                    auto const& tx = *it->first;
+                    BEAST_EXPECT(tx.getTxnType() == ttCRON);
+                }
+            }
+
+            // proceed ledger
+            env.close();
+            {
+                auto const txns = env.closed()->txs;
+                auto size = std::distance(txns.begin(), txns.end());
+                BEAST_EXPECT(size == 0);
+            }
+        }
+    }
+
+    void
+    testWithFeats(FeatureBitset features)
+    {
+        testEnabled(features);
+        testFee(features);
+        testInvalidPreflight(features);
+        testInvalidPreclaim(features);
+        testDoApply(features);
+
+        testCronExecution(features);
+    }
+
+public:
+    void
+    run() override
+    {
+        using namespace test::jtx;
+        auto const sa = supported_amendments();
+        testWithFeats(sa);
+    }
+};
+
+BEAST_DEFINE_TESTSUITE(Cron, app, ripple);
+
+}  // namespace test
+}  // namespace ripple

src/test/app/SetHookTSH_test.cpp

@@ -22,6 +22,7 @@
 #include <ripple/app/misc/HashRouter.h>
 #include <ripple/app/misc/TxQ.h>
 #include <ripple/app/tx/apply.h>
+#include <ripple/basics/StringUtilities.h>
 #include <ripple/protocol/Feature.h>
 #include <ripple/protocol/PayChan.h>
 #include <ripple/protocol/jss.h>
@@ -748,10 +749,22 @@ private:
         jtx::Env& env,
         int const& expected,
         uint64_t const& lineno)
+    {
+        auto const hashStr =
+            env.tx()->getJson(JsonOptions::none)[jss::hash].asString();
+        uint256 const txHash = uint256::fromVoid(strUnHex(hashStr)->data());
+        testTSHStrongWeak(env, txHash, expected, lineno);
+    }
+
+    void
+    testTSHStrongWeak(
+        jtx::Env& env,
+        uint256 const& txHash,
+        int const& expected,
+        uint64_t const& lineno)
     {
         Json::Value params;
-        params[jss::transaction] =
-            env.tx()->getJson(JsonOptions::none)[jss::hash];
+        params[jss::transaction] = strHex(txHash);
         auto const jrr = env.rpc("json", "tx", to_string(params));
         auto const meta = jrr[jss::result][jss::meta];
         validateTSHStrongWeak(meta, expected, lineno);
@@ -6251,6 +6264,107 @@ private:
         }
     }
 
+    // CronSet
+    // | otxn | tsh | cset |
+    // |   A  |  A  |  S   |
+    void
+    testCronSetTSH(FeatureBitset features)
+    {
+        testcase("cron set tsh");
+
+        using namespace test::jtx;
+        using namespace std::literals;
+
+        // otxn: account
+        // tsh account
+        // w/s: strong
+        for (bool const testStrong : {true, false})
+        {
+            test::jtx::Env env{
+                *this,
+                network::makeNetworkConfig(21337, "10", "1000000", "200000"),
+                features};
+
+            auto const account = Account("alice");
+            env.fund(XRP(1000), account);
+            env.close();
+
+            if (!testStrong)
+                addWeakTSH(env, account);
+
+            // set tsh hook
+            setTSHHook(env, account, testStrong);
+
+            // cron set
+            env(cron::set(account),
+                cron::startTime(0),
+                cron::delay(100),
+                cron::repeat(1),
+                fee(XRP(1)),
+                ter(tesSUCCESS));
+            env.close();
+
+            // verify tsh hook triggered
+            testTSHStrongWeak(env, tshSTRONG, __LINE__);
+        }
+    }
+
+    // | otxn | tsh | cron |
+    // |   -  |  O  |  W   |
+    void
+    testCronTSH(FeatureBitset features)
+    {
+        testcase("cron tsh");
+
+        using namespace test::jtx;
+        using namespace std::literals;
+
+        // otxn: -
+        // tsh owner
+        // w/s: weak
+        for (bool const testStrong : {true, false})
+        {
+            test::jtx::Env env{
+                *this,
+                network::makeNetworkConfig(21337, "10", "1000000", "200000"),
+                features};
+
+            auto const account = Account("alice");
+            env.fund(XRP(1000), account);
+            env.close();
+
+            auto const baseTime =
+                env.current()->parentCloseTime().time_since_epoch().count();
+            // cron set
+            env(cron::set(account),
+                cron::startTime(baseTime + 100),
+                cron::delay(100),
+                cron::repeat(1),
+                fee(XRP(1)),
+                ter(tesSUCCESS));
+            env.close();
+
+            if (!testStrong)
+                addWeakTSH(env, account);
+
+            // set tsh hook
+            setTSHHook(env, account, testStrong);
+
+            // proceed ledger
+            env.close(100s);
+
+            // close ledger
+            env.close();
+
+            // verify tsh hook triggered
+            auto const expected = testStrong ? tshNONE : tshWEAK;
+            auto const txs = env.closed()->txs;
+            BEAST_EXPECT(std::distance(txs.begin(), txs.end()) == 1);
+            auto const tx = txs.begin()->first;
+            BEAST_EXPECT(tx->getTxnType() == ttCRON);
+            testTSHStrongWeak(env, tx->getTransactionID(), expected, __LINE__);
+        }
+    }
     void
     testEmissionOrdering(FeatureBitset features)
     {
@@ -6398,6 +6512,8 @@ private:
         testURITokenCancelSellOfferTSH(features);
         testURITokenCreateSellOfferTSH(features);
         testRemitTSH(features);
+        testCronSetTSH(features);
+        testCronTSH(features);
     }
 
     void

src/test/consensus/UNLReport_test.cpp

@@ -357,6 +357,32 @@ class UNLReport_test : public beast::unit_test::suite
             BEAST_EXPECT(isImportVL(env, ivlKeys[0]) == true);
             BEAST_EXPECT(isImportVL(env, ivlKeys[1]) == false);
             BEAST_EXPECT(isActiveValidator(env, vlKeys[0]) == true);
+
+            // now test unrecognised keys that are already present in the ledger
+            // object (flap fix)
+            l = std::make_shared<Ledger>(
+                *l, env.app().timeKeeper().closeTime());
+
+            // insert a ttUNL_REPORT pseudo into the open ledger
+            env.app().openLedger().modify(
+                [&](OpenView& view, beast::Journal j) -> bool {
+                    STTx tx = createUNLRTx(l->seq(), ivlKeys[1], vlKeys[0]);
+                    uint256 txID = tx.getTransactionID();
+                    auto s = std::make_shared<ripple::Serializer>();
+                    tx.add(*s);
+                    env.app().getHashRouter().setFlags(txID, SF_PRIVATE2);
+                    view.rawTxInsert(txID, std::move(s), nullptr);
+                    return true;
+                });
+
+            BEAST_EXPECT(hasUNLReport(env) == true);
+
+            // close the ledger
+            env.close();
+
+            BEAST_EXPECT(isImportVL(env, ivlKeys[0]) == true);
+            BEAST_EXPECT(isImportVL(env, ivlKeys[1]) == false);
+            BEAST_EXPECT(isActiveValidator(env, vlKeys[0]) == true);
         }
     }
 
@@ -1324,4 +1350,4 @@ createUNLRTx(
 }
 
 }  // namespace test
-}  // namespace ripple
+}  // namespace ripple

src/test/jtx.h

@@ -33,6 +33,7 @@
 #include <test/jtx/amount.h>
 #include <test/jtx/balance.h>
 #include <test/jtx/check.h>
+#include <test/jtx/cron.h>
 #include <test/jtx/delivermin.h>
 #include <test/jtx/deposit.h>
 #include <test/jtx/escrow.h>

src/test/jtx/cron.h

@@ -0,0 +1,89 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of rippled: https://github.com/ripple/rippled
+    Copyright (c) 2025 XRPL Labs
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#ifndef RIPPLE_TEST_JTX_CRON_H_INCLUDED
+#define RIPPLE_TEST_JTX_CRON_H_INCLUDED
+
+#include <test/jtx/Account.h>
+#include <test/jtx/Env.h>
+
+namespace ripple {
+namespace test {
+namespace jtx {
+
+/** Cron operations. */
+namespace cron {
+
+/** Set a cron. */
+Json::Value
+set(jtx::Account const& account);
+
+/** Sets the optional StartTime on a JTx. */
+class startTime
+{
+private:
+    uint32_t startTime_;
+
+public:
+    explicit startTime(uint32_t startTime) : startTime_(startTime)
+    {
+    }
+
+    void
+    operator()(Env&, JTx& jtx) const;
+};
+
+/** Sets the optional DelaySeconds on a JTx. */
+class delay
+{
+private:
+    uint32_t delay_;
+
+public:
+    explicit delay(uint32_t delay) : delay_(delay)
+    {
+    }
+
+    void
+    operator()(Env&, JTx& jtx) const;
+};
+
+/** Sets the optional RepeatCount on a JTx. */
+class repeat
+{
+private:
+    uint32_t repeat_;
+
+public:
+    explicit repeat(uint32_t repeat) : repeat_(repeat)
+    {
+    }
+
+    void
+    operator()(Env&, JTx& jtx) const;
+};
+
+}  // namespace cron
+
+}  // namespace jtx
+
+}  // namespace test
+}  // namespace ripple
+
+#endif  // RIPPLE_TEST_JTX_CRON_H_INCLUDED

src/test/jtx/impl/cron.cpp

@@ -0,0 +1,62 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of rippled: https://github.com/ripple/rippled
+    Copyright (c) 2025 XRPL Labs
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include <ripple/protocol/jss.h>
+#include <test/jtx/cron.h>
+
+namespace ripple {
+namespace test {
+namespace jtx {
+
+namespace cron {
+
+// Set a cron.
+Json::Value
+set(jtx::Account const& account)
+{
+    using namespace jtx;
+    Json::Value jv;
+    jv[jss::TransactionType] = jss::CronSet;
+    jv[jss::Account] = account.human();
+    return jv;
+}
+
+void
+startTime::operator()(Env& env, JTx& jt) const
+{
+    jt.jv[sfStartTime.jsonName] = startTime_;
+}
+
+void
+delay::operator()(Env& env, JTx& jt) const
+{
+    jt.jv[sfDelaySeconds.jsonName] = delay_;
+}
+
+void
+repeat::operator()(Env& env, JTx& jt) const
+{
+    jt.jv[sfRepeatCount.jsonName] = repeat_;
+}
+
+}  // namespace cron
+
+}  // namespace jtx
+}  // namespace test
+}  // namespace ripple

src/test/nodestore/NuDBFactory_test.cpp

@@ -0,0 +1,357 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of rippled: https://github.com/ripple/rippled
+    Copyright (c) 2012, 2013 Ripple Labs Inc.
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include <test/nodestore/TestBase.h>
+#include <test/unit_test/SuiteJournal.h>
+
+#include <ripple/basics/BasicConfig.h>
+#include <ripple/basics/ByteUtilities.h>
+#include <ripple/beast/utility/temp_dir.h>
+#include <ripple/nodestore/DummyScheduler.h>
+#include <ripple/nodestore/Manager.h>
+
+#include <memory>
+#include <sstream>
+
+namespace ripple {
+namespace NodeStore {
+
+class NuDBFactory_test : public TestBase
+{
+private:
+    // Helper function to create a Section with specified parameters
+    Section
+    createSection(std::string const& path, std::string const& blockSize = "")
+    {
+        Section params;
+        params.set("type", "nudb");
+        params.set("path", path);
+        if (!blockSize.empty())
+            params.set("nudb_block_size", blockSize);
+        return params;
+    }
+
+    // Helper function to create a backend and test basic functionality
+    bool
+    testBackendFunctionality(
+        Section const& params,
+        std::size_t expectedBlocksize)
+    {
+        try
+        {
+            DummyScheduler scheduler;
+            test::SuiteJournal journal("NuDBFactory_test", *this);
+
+            auto backend = Manager::instance().make_Backend(
+                params, megabytes(4), scheduler, journal);
+
+            if (!BEAST_EXPECT(backend))
+                return false;
+
+            if (!BEAST_EXPECT(backend->getBlockSize() == expectedBlocksize))
+                return false;
+
+            backend->open();
+
+            if (!BEAST_EXPECT(backend->isOpen()))
+                return false;
+
+            // Test basic store/fetch functionality
+            auto batch = createPredictableBatch(10, 12345);
+            storeBatch(*backend, batch);
+
+            Batch copy;
+            fetchCopyOfBatch(*backend, &copy, batch);
+
+            backend->close();
+
+            return areBatchesEqual(batch, copy);
+        }
+        catch (...)
+        {
+            return false;
+        }
+    }
+
+    // Helper function to test log messages
+    void
+    testLogMessage(
+        Section const& params,
+        beast::severities::Severity level,
+        std::string const& expectedMessage)
+    {
+        test::StreamSink sink(level);
+        beast::Journal journal(sink);
+
+        DummyScheduler scheduler;
+        auto backend = Manager::instance().make_Backend(
+            params, megabytes(4), scheduler, journal);
+
+        std::string logOutput = sink.messages().str();
+        BEAST_EXPECT(logOutput.find(expectedMessage) != std::string::npos);
+    }
+
+public:
+    void
+    testDefaultBlockSize()
+    {
+        testcase("Default block size (no nudb_block_size specified)");
+
+        beast::temp_dir tempDir;
+        auto params = createSection(tempDir.path());
+
+        // Should work with default 4096 block size
+        BEAST_EXPECT(testBackendFunctionality(params, 4096));
+    }
+
+    void
+    testValidBlockSizes()
+    {
+        testcase("Valid block sizes");
+
+        std::vector<std::size_t> validSizes = {4096, 8192, 16384, 32768};
+
+        for (auto const& size : validSizes)
+        {
+            beast::temp_dir tempDir;
+            auto params = createSection(tempDir.path(), to_string(size));
+
+            BEAST_EXPECT(testBackendFunctionality(params, size));
+        }
+    }
+
+    void
+    testInvalidBlockSizes()
+    {
+        testcase("Invalid block sizes");
+
+        std::vector<std::string> invalidSizes = {
+            "2048",    // Too small
+            "1024",    // Too small
+            "65536",   // Too large
+            "131072",  // Too large
+            "5000",    // Not power of 2
+            "6000",    // Not power of 2
+            "10000",   // Not power of 2
+            "0",       // Zero
+            "-1",      // Negative
+            "abc",     // Non-numeric
+            "4k",      // Invalid format
+            "4096.5"   // Decimal
+        };
+
+        for (auto const& size : invalidSizes)
+        {
+            beast::temp_dir tempDir;
+            auto params = createSection(tempDir.path(), size);
+
+            DummyScheduler scheduler;
+            test::SuiteJournal journal("NuDBFactory_test", *this);
+
+            // Should throw exception for invalid sizes
+            try
+            {
+                auto backend = Manager::instance().make_Backend(
+                    params, megabytes(4), scheduler, journal);
+                // If we get here, the test failed
+                BEAST_EXPECT(false);
+            }
+            catch (std::exception const& e)
+            {
+                // Expected exception
+                std::string error{e.what()};
+                BEAST_EXPECT(
+                    error.find("Invalid nudb_block_size") != std::string::npos);
+            }
+        }
+    }
+
+    void
+    testLogMessages()
+    {
+        testcase("Log message verification");
+
+        // Test valid custom block size logging
+        {
+            beast::temp_dir tempDir;
+            auto params = createSection(tempDir.path(), "8192");
+
+            testLogMessage(
+                params,
+                beast::severities::kInfo,
+                "Using custom NuDB block size: 8192");
+        }
+
+        // Test invalid block size exception message
+        {
+            beast::temp_dir tempDir;
+            auto params = createSection(tempDir.path(), "5000");
+
+            test::StreamSink sink(beast::severities::kWarning);
+            beast::Journal journal(sink);
+
+            DummyScheduler scheduler;
+            try
+            {
+                auto backend = Manager::instance().make_Backend(
+                    params, megabytes(4), scheduler, journal);
+                fail();
+            }
+            catch (std::exception const& e)
+            {
+                std::string logOutput{e.what()};
+                BEAST_EXPECT(
+                    logOutput.find("Invalid nudb_block_size: 5000") !=
+                    std::string::npos);
+                BEAST_EXPECT(
+                    logOutput.find(
+                        "Must be power of 2 between 4096 and 32768") !=
+                    std::string::npos);
+            }
+        }
+
+        // Test non-numeric value exception message
+        {
+            beast::temp_dir tempDir;
+            auto params = createSection(tempDir.path(), "invalid");
+
+            test::StreamSink sink(beast::severities::kWarning);
+            beast::Journal journal(sink);
+
+            DummyScheduler scheduler;
+            try
+            {
+                auto backend = Manager::instance().make_Backend(
+                    params, megabytes(4), scheduler, journal);
+
+                fail();
+            }
+            catch (std::exception const& e)
+            {
+                std::string logOutput{e.what()};
+                BEAST_EXPECT(
+                    logOutput.find("Invalid nudb_block_size value: invalid") !=
+                    std::string::npos);
+            }
+        }
+    }
+
+    void
+    testPowerOfTwoValidation()
+    {
+        testcase("Power of 2 validation logic");
+
+        // Test edge cases around valid range
+        std::vector<std::pair<std::string, bool>> testCases = {
+            {"4095", false},   // Just below minimum
+            {"4096", true},    // Minimum valid
+            {"4097", false},   // Just above minimum, not power of 2
+            {"8192", true},    // Valid power of 2
+            {"8193", false},   // Just above valid power of 2
+            {"16384", true},   // Valid power of 2
+            {"32768", true},   // Maximum valid
+            {"32769", false},  // Just above maximum
+            {"65536", false}   // Power of 2 but too large
+        };
+
+        for (auto const& [size, shouldWork] : testCases)
+        {
+            beast::temp_dir tempDir;
+            auto params = createSection(tempDir.path(), size);
+
+            test::StreamSink sink(beast::severities::kWarning);
+            beast::Journal journal(sink);
+
+            DummyScheduler scheduler;
+            try
+            {
+                auto backend = Manager::instance().make_Backend(
+                    params, megabytes(4), scheduler, journal);
+                BEAST_EXPECT(shouldWork);
+            }
+            catch (std::exception const& e)
+            {
+                std::string logOutput{e.what()};
+                BEAST_EXPECT(
+                    logOutput.find("Invalid nudb_block_size") !=
+                    std::string::npos);
+                BEAST_EXPECT(!shouldWork);
+            }
+        }
+    }
+
+    void
+    testDataPersistence()
+    {
+        testcase("Data persistence with different block sizes");
+
+        std::vector<std::string> blockSizes = {
+            "4096", "8192", "16384", "32768"};
+
+        for (auto const& size : blockSizes)
+        {
+            beast::temp_dir tempDir;
+            auto params = createSection(tempDir.path(), size);
+
+            DummyScheduler scheduler;
+            test::SuiteJournal journal("NuDBFactory_test", *this);
+
+            // Create test data
+            auto batch = createPredictableBatch(50, 54321);
+
+            // Store data
+            {
+                auto backend = Manager::instance().make_Backend(
+                    params, megabytes(4), scheduler, journal);
+                backend->open();
+                storeBatch(*backend, batch);
+                backend->close();
+            }
+
+            // Retrieve data in new backend instance
+            {
+                auto backend = Manager::instance().make_Backend(
+                    params, megabytes(4), scheduler, journal);
+                backend->open();
+
+                Batch copy;
+                fetchCopyOfBatch(*backend, &copy, batch);
+
+                BEAST_EXPECT(areBatchesEqual(batch, copy));
+                backend->close();
+            }
+        }
+    }
+
+    void
+    run() override
+    {
+        testDefaultBlockSize();
+        testValidBlockSizes();
+        testInvalidBlockSizes();
+        testLogMessages();
+        testPowerOfTwoValidation();
+        testDataPersistence();
+    }
+};
+
+BEAST_DEFINE_TESTSUITE(NuDBFactory, ripple_core, ripple);
+
+}  // namespace NodeStore
+}  // namespace ripple