Merge branch 'mvadari/rearch/account' into mvadari/rearch/token

include/xrpl/basics/BasicConfig.h

@@ -311,7 +311,7 @@ template <class T>
 bool
 set(T& target, T const& defaultValue, std::string const& name, Section const& section)
 {
-    bool found_and_valid = set<T>(target, name, section);
+    bool const found_and_valid = set<T>(target, name, section);
     if (!found_and_valid)
         target = defaultValue;
     return found_and_valid;

include/xrpl/basics/CountedObject.h

@@ -34,7 +34,7 @@ public:
         {
             // Insert ourselves at the front of the lock-free linked list
             CountedObjects& instance = CountedObjects::getInstance();
-            Counter* head;
+            Counter* head = nullptr;
 
             do
             {
@@ -99,7 +99,7 @@ private:
     Derived classes have their instances counted automatically. This is used
     for reporting purposes.
 
-    @ingroup ripple_basics
+    @ingroup basics
 */
 template <class Object>
 class CountedObject

include/xrpl/basics/DecayingSample.h

@@ -93,7 +93,7 @@ class DecayWindow
 public:
     using time_point = typename Clock::time_point;
 
-    explicit DecayWindow(time_point now) : value_(0), when_(now)
+    explicit DecayWindow(time_point now) : when_(now)
     {
     }
 
@@ -125,7 +125,7 @@ private:
         when_ = now;
     }
 
-    double value_;
+    double value_{0};
     time_point when_;
 };
 

include/xrpl/basics/IntrusivePointer.h

@@ -59,7 +59,7 @@ concept CAdoptTag = std::is_same_v<T, SharedIntrusiveAdoptIncrementStrongTag> ||
     still retaining the reference counts. For example, for SHAMapInnerNodes the
     children may be reset in that function. Note that std::shared_pointer WILL
     run the destructor when the strong count reaches zero, but may not free the
-    memory used by the object until the weak count reaches zero. In rippled, we
+    memory used by the object until the weak count reaches zero. In xrpld, we
     typically allocate shared pointers with the `make_shared` function. When
     that is used, the memory is not reclaimed until the weak count reaches zero.
 */
@@ -84,7 +84,8 @@ public:
 
     template <class TT>
         requires std::convertible_to<TT*, T*>
-    SharedIntrusive(SharedIntrusive<TT>&& rhs);
+    SharedIntrusive(
+        SharedIntrusive<TT>&& rhs);  // NOLINT(cppcoreguidelines-rvalue-reference-param-not-moved)
 
     SharedIntrusive&
     operator=(SharedIntrusive const& rhs);
@@ -106,7 +107,8 @@ public:
     template <class TT>
         requires std::convertible_to<TT*, T*>
     SharedIntrusive&
-    operator=(SharedIntrusive<TT>&& rhs);
+    operator=(
+        SharedIntrusive<TT>&& rhs);  // NOLINT(cppcoreguidelines-rvalue-reference-param-not-moved)
 
     /** Adopt the raw pointer. The strong reference may or may not be
         incremented, depending on the TAdoptTag
@@ -314,7 +316,8 @@ public:
 
     template <class TT>
         requires std::convertible_to<TT*, T*>
-    SharedWeakUnion(SharedIntrusive<TT>&& rhs);
+    SharedWeakUnion(
+        SharedIntrusive<TT>&& rhs);  // NOLINT(cppcoreguidelines-rvalue-reference-param-not-moved)
 
     SharedWeakUnion&
     operator=(SharedWeakUnion const& rhs);
@@ -327,7 +330,8 @@ public:
     template <class TT>
         requires std::convertible_to<TT*, T*>
     SharedWeakUnion&
-    operator=(SharedIntrusive<TT>&& rhs);
+    operator=(
+        SharedIntrusive<TT>&& rhs);  // NOLINT(cppcoreguidelines-rvalue-reference-param-not-moved)
 
     ~SharedWeakUnion();
 

include/xrpl/basics/IntrusivePointer.ipp

@@ -68,9 +68,7 @@ SharedIntrusive<T>::operator=(SharedIntrusive const& rhs)
 
 template <class T>
 template <class TT>
-// clang-format off
-requires std::convertible_to<TT*, T*>
-// clang-format on
+    requires std::convertible_to<TT*, T*>
 SharedIntrusive<T>&
 SharedIntrusive<T>::operator=(SharedIntrusive<TT> const& rhs)
 {
@@ -101,9 +99,7 @@ SharedIntrusive<T>::operator=(SharedIntrusive&& rhs)
 
 template <class T>
 template <class TT>
-// clang-format off
-requires std::convertible_to<TT*, T*>
-// clang-format on
+    requires std::convertible_to<TT*, T*>
 SharedIntrusive<T>&
 SharedIntrusive<T>::operator=(SharedIntrusive<TT>&& rhs)
 {
@@ -307,9 +303,7 @@ WeakIntrusive<T>::WeakIntrusive(SharedIntrusive<T> const& rhs) : ptr_{rhs.unsafe
 
 template <class T>
 template <class TT>
-// clang-format off
-requires std::convertible_to<TT*, T*>
-// clang-format on
+    requires std::convertible_to<TT*, T*>
 WeakIntrusive<T>&
 WeakIntrusive<T>::operator=(SharedIntrusive<TT> const& rhs)
 {
@@ -454,9 +448,7 @@ SharedWeakUnion<T>::operator=(SharedWeakUnion const& rhs)
 
 template <class T>
 template <class TT>
-// clang-format off
-requires std::convertible_to<TT*, T*>
-// clang-format on
+    requires std::convertible_to<TT*, T*>
 SharedWeakUnion<T>&
 SharedWeakUnion<T>::operator=(SharedIntrusive<TT> const& rhs)
 {
@@ -470,9 +462,7 @@ SharedWeakUnion<T>::operator=(SharedIntrusive<TT> const& rhs)
 
 template <class T>
 template <class TT>
-// clang-format off
-requires std::convertible_to<TT*, T*>
-// clang-format on
+    requires std::convertible_to<TT*, T*>
 SharedWeakUnion<T>&
 SharedWeakUnion<T>::operator=(SharedIntrusive<TT>&& rhs)
 {

include/xrpl/basics/IntrusiveRefCounts.h

@@ -33,7 +33,7 @@ enum class ReleaseWeakRefAction { noop, destroy };
 /** Implement the strong count, weak count, and bit flags for an intrusive
     pointer.
 
-    A class can satisfy the requirements of a xrpl::IntrusivePointer by
+    A class can satisfy the requirements of an xrpl::IntrusivePointer by
     inheriting from this class.
   */
 struct IntrusiveRefCounts
@@ -448,7 +448,7 @@ inline void
 partialDestructorFinished(T** o)
 {
     T& self = **o;
-    IntrusiveRefCounts::RefCountPair p =
+    IntrusiveRefCounts::RefCountPair const p =
         self.refCounts.fetch_or(IntrusiveRefCounts::partialDestroyFinishedMask);
     XRPL_ASSERT(
         (!p.partialDestroyFinishedBit && p.partialDestroyStartedBit && !p.strong),

include/xrpl/basics/Number.h

@@ -73,12 +73,12 @@ struct MantissaRange
     enum mantissa_scale { small, large };
 
     explicit constexpr MantissaRange(mantissa_scale scale_)
-        : min(getMin(scale_)), max(min * 10 - 1), log(logTen(min).value_or(-1)), scale(scale_)
+        : min(getMin(scale_)), log(logTen(min).value_or(-1)), scale(scale_)
     {
     }
 
     rep min;
-    rep max;
+    rep max{min * 10 - 1};
     int log;
     mantissa_scale scale;
 

include/xrpl/basics/README.md

@@ -2,9 +2,9 @@
 
 Utility functions and classes.
 
-ripple/basic should contain no dependencies on other modules.
+The module xrpl/basics should contain no dependencies on other modules.
 
-# Choosing a rippled container.
+# Choosing an xrpld container.
 
 - `std::vector`
   - For ordered containers with most insertions or erases at the end.

include/xrpl/basics/SlabAllocator.h

@@ -91,10 +91,10 @@ class SlabAllocator
         std::uint8_t*
         allocate() noexcept
         {
-            std::uint8_t* ret;
+            std::uint8_t* ret = nullptr;  // NOLINT(misc-const-correctness)
 
             {
-                std::lock_guard l(m_);
+                std::lock_guard const l(m_);
 
                 ret = l_;
 
@@ -123,7 +123,7 @@ class SlabAllocator
         {
             XRPL_ASSERT(own(ptr), "xrpl::SlabAllocator::SlabBlock::deallocate : own input");
 
-            std::lock_guard l(m_);
+            std::lock_guard const l(m_);
 
             // Use memcpy to avoid unaligned UB
             // (will optimize to equivalent code)
@@ -210,16 +210,13 @@ public:
 
         // No slab can satisfy our request, so we attempt to allocate a new
         // one here:
-        std::size_t size = slabSize_;
+        std::size_t const size = slabSize_;
 
         // We want to allocate the memory at a 2 MiB boundary, to make it
         // possible to use hugepage mappings on Linux:
         auto buf = boost::alignment::aligned_alloc(megabytes(std::size_t(2)), size);
-
-        // clang-format off
         if (!buf) [[unlikely]]
             return nullptr;
-        // clang-format on
 
 #if BOOST_OS_LINUX
         // When allocating large blocks, attempt to leverage Linux's

include/xrpl/basics/StringUtilities.h

@@ -66,12 +66,12 @@ strUnHex(std::size_t strSize, Iterator begin, Iterator end)
 
     while (iter != end)
     {
-        int cHigh = digitLookupTable[*iter++];
+        int const cHigh = digitLookupTable[*iter++];
 
         if (cHigh < 0)
             return {};
 
-        int cLow = digitLookupTable[*iter++];
+        int const cLow = digitLookupTable[*iter++];
 
         if (cLow < 0)
             return {};

include/xrpl/basics/TaggedCache.h

@@ -182,8 +182,7 @@ private:
             : hook(collector->make_hook(handler))
             , size(collector->make_gauge(prefix, "size"))
             , hit_rate(collector->make_gauge(prefix, "hit_rate"))
-            , hits(0)
-            , misses(0)
+
         {
         }
 
@@ -191,8 +190,8 @@ private:
         beast::insight::Gauge size;
         beast::insight::Gauge hit_rate;
 
-        std::size_t hits;
-        std::size_t misses;
+        std::size_t hits{0};
+        std::size_t misses{0};
     };
 
     class KeyOnlyEntry
@@ -294,10 +293,10 @@ private:
     clock_type::duration const m_target_age;
 
     // Number of items cached
-    int m_cache_count;
+    int m_cache_count{0};
     cache_type m_cache;  // Hold strong reference to recent objects
-    std::uint64_t m_hits;
-    std::uint64_t m_misses;
+    std::uint64_t m_hits{0};
+    std::uint64_t m_misses{0};
 };
 
 }  // namespace xrpl

include/xrpl/basics/TaggedCache.ipp

@@ -36,9 +36,7 @@ inline TaggedCache<
     , m_name(name)
     , m_target_size(size)
     , m_target_age(expiration)
-    , m_cache_count(0)
-    , m_hits(0)
-    , m_misses(0)
+
 {
 }
 

include/xrpl/basics/UptimeClock.h

@@ -26,7 +26,7 @@ public:
     explicit UptimeClock() = default;
 
     static time_point
-    now();  // seconds since rippled program start
+    now();  // seconds since xrpld program start
 
 private:
     static std::atomic<rep> now_;

include/xrpl/basics/base_uint.h

@@ -212,7 +212,7 @@ private:
         while (in != sv.end())
         {
             std::uint32_t accum = {};
-            for (std::uint32_t shift : {4u, 0u, 12u, 8u, 20u, 16u, 28u, 24u})
+            for (std::uint32_t const shift : {4u, 0u, 12u, 8u, 20u, 16u, 28u, 24u})
             {
                 if (auto const result = hexCharToUInt(*in++, shift, accum);
                     result != ParseResult::okay)
@@ -335,11 +335,13 @@ public:
     operator=(std::uint64_t uHost)
     {
         *this = beast::zero;
+        // NOLINTBEGIN(cppcoreguidelines-pro-type-member-init)
         union
         {
             unsigned u[2];
             std::uint64_t ul;
         };
+        // NOLINTEND(cppcoreguidelines-pro-type-member-init)
         // Put in least significant bits.
         ul = boost::endian::native_to_big(uHost);
         data_[WIDTH - 2] = u[0];
@@ -444,7 +446,7 @@ public:
 
         for (int i = WIDTH; i--;)
         {
-            std::uint64_t n = carry + boost::endian::big_to_native(data_[i]) +
+            std::uint64_t const n = carry + boost::endian::big_to_native(data_[i]) +
                 boost::endian::big_to_native(b.data_[i]);
 
             data_[i] = boost::endian::native_to_big(static_cast<std::uint32_t>(n));
@@ -621,7 +623,7 @@ template <>
 inline std::size_t
 extract(uint256 const& key)
 {
-    std::size_t result;
+    std::size_t result = 0;
     // Use memcpy to avoid unaligned UB
     // (will optimize to equivalent code)
     std::memcpy(&result, key.data(), sizeof(std::size_t));

include/xrpl/basics/contract.h

@@ -54,7 +54,7 @@ Throw(Args&&... args)
 
     E e(std::forward<Args>(args)...);
     LogThrow(std::string("Throwing exception of type " + beast::type_name<E>() + ": ") + e.what());
-    throw e;
+    throw std::move(e);
 }
 
 /** Called when faulty logic causes a broken invariant. */

include/xrpl/basics/hardened_hash.h

@@ -32,7 +32,7 @@ make_seed_pair() noexcept
         // state_t& operator=(state_t const&) = delete;
     };
     static state_t state;
-    std::lock_guard lock(state.mutex);
+    std::lock_guard const lock(state.mutex);
     return {state.dist(state.gen), state.dist(state.gen)};
 }
 

include/xrpl/basics/random.h

@@ -14,14 +14,16 @@ namespace xrpl {
 
 #ifndef __INTELLISENSE__
 static_assert(
+    // NOLINTNEXTLINE(misc-redundant-expression)
     std::is_integral<beast::xor_shift_engine::result_type>::value &&
         std::is_unsigned<beast::xor_shift_engine::result_type>::value,
-    "The Ripple default PRNG engine must return an unsigned integral type.");
+    "The XRPL default PRNG engine must return an unsigned integral type.");
 
 static_assert(
+    // NOLINTNEXTLINE(misc-redundant-expression)
     std::numeric_limits<beast::xor_shift_engine::result_type>::max() >=
         std::numeric_limits<std::uint64_t>::max(),
-    "The Ripple default PRNG engine return must be at least 64 bits wide.");
+    "The XRPL default PRNG engine return must be at least 64 bits wide.");
 #endif
 
 namespace detail {
@@ -56,9 +58,9 @@ default_prng()
 
     // The thread-specific PRNGs:
     thread_local beast::xor_shift_engine engine = [] {
-        std::uint64_t seed;
+        std::uint64_t seed = 0;
         {
-            std::lock_guard lk(m);
+            std::lock_guard const lk(m);
             std::uniform_int_distribution<std::uint64_t> distribution{1};
             seed = distribution(seeder);
         }

include/xrpl/beast/asio/io_latency_probe.h

@@ -23,15 +23,15 @@ private:
 
     std::recursive_mutex m_mutex;
     std::condition_variable_any m_cond;
-    std::size_t m_count;
+    std::size_t m_count{1};
     duration const m_period;
     boost::asio::io_context& m_ios;
     boost::asio::basic_waitable_timer<std::chrono::steady_clock> m_timer;
-    bool m_cancel;
+    bool m_cancel{false};
 
 public:
     io_latency_probe(duration const& period, boost::asio::io_context& ios)
-        : m_count(1), m_period(period), m_ios(ios), m_timer(m_ios), m_cancel(false)
+        : m_period(period), m_ios(ios), m_timer(m_ios)
     {
     }
 
@@ -83,7 +83,7 @@ public:
     void
     sample_one(Handler&& handler)
     {
-        std::lock_guard lock(m_mutex);
+        std::lock_guard const lock(m_mutex);
         if (m_cancel)
             throw std::logic_error("io_latency_probe is canceled");
         boost::asio::post(
@@ -98,7 +98,7 @@ public:
     void
     sample(Handler&& handler)
     {
-        std::lock_guard lock(m_mutex);
+        std::lock_guard const lock(m_mutex);
         if (m_cancel)
             throw std::logic_error("io_latency_probe is canceled");
         boost::asio::post(
@@ -122,14 +122,14 @@ private:
     void
     addref()
     {
-        std::lock_guard lock(m_mutex);
+        std::lock_guard const lock(m_mutex);
         ++m_count;
     }
 
     void
     release()
     {
-        std::lock_guard lock(m_mutex);
+        std::lock_guard const lock(m_mutex);
         if (--m_count == 0)
             m_cond.notify_all();
     }
@@ -192,7 +192,7 @@ private:
             m_handler(elapsed);
 
             {
-                std::lock_guard lock(m_probe->m_mutex);
+                std::lock_guard const lock(m_probe->m_mutex);
                 if (m_probe->m_cancel)
                     return;
             }

include/xrpl/beast/container/aged_map.h

@@ -16,4 +16,4 @@ template <
     class Allocator = std::allocator<std::pair<Key const, T>>>
 using aged_map = detail::aged_ordered_container<false, true, Key, T, Clock, Compare, Allocator>;
 
-}
+}  // namespace beast

include/xrpl/beast/container/aged_multimap.h

@@ -16,4 +16,4 @@ template <
     class Allocator = std::allocator<std::pair<Key const, T>>>
 using aged_multimap = detail::aged_ordered_container<true, true, Key, T, Clock, Compare, Allocator>;
 
-}
+}  // namespace beast

include/xrpl/beast/container/aged_multiset.h

@@ -15,4 +15,4 @@ template <
     class Allocator = std::allocator<Key>>
 using aged_multiset =
     detail::aged_ordered_container<true, false, Key, void, Clock, Compare, Allocator>;
-}
+}  // namespace beast

include/xrpl/beast/container/aged_set.h

@@ -15,4 +15,4 @@ template <
     class Allocator = std::allocator<Key>>
 using aged_set = detail::aged_ordered_container<false, false, Key, void, Clock, Compare, Allocator>;
 
-}
+}  // namespace beast

include/xrpl/beast/container/aged_unordered_map.h

@@ -17,4 +17,4 @@ template <
     class Allocator = std::allocator<std::pair<Key const, T>>>
 using aged_unordered_map =
     detail::aged_unordered_container<false, true, Key, T, Clock, Hash, KeyEqual, Allocator>;
-}
+}  // namespace beast

include/xrpl/beast/container/aged_unordered_multimap.h

@@ -17,4 +17,4 @@ template <
     class Allocator = std::allocator<std::pair<Key const, T>>>
 using aged_unordered_multimap =
     detail::aged_unordered_container<true, true, Key, T, Clock, Hash, KeyEqual, Allocator>;
-}
+}  // namespace beast

include/xrpl/beast/container/aged_unordered_multiset.h

@@ -17,4 +17,4 @@ template <
 using aged_unordered_multiset =
     detail::aged_unordered_container<true, false, Key, void, Clock, Hash, KeyEqual, Allocator>;
 
-}
+}  // namespace beast

include/xrpl/beast/container/aged_unordered_set.h

@@ -16,4 +16,4 @@ template <
     class Allocator = std::allocator<Key>>
 using aged_unordered_set =
     detail::aged_unordered_container<false, false, Key, void, Clock, Hash, KeyEqual, Allocator>;
-}
+}  // namespace beast

include/xrpl/beast/container/detail/aged_ordered_container.h

@@ -262,7 +262,9 @@ private:
         {
         }
 
-        config_t(config_t&& other, Allocator const& alloc)
+        config_t(
+            config_t&& other,  // NOLINT(cppcoreguidelines-rvalue-reference-param-not-moved)
+            Allocator const& alloc)
             : KeyValueCompare(std::move(other.key_compare()))
             , beast::detail::empty_base_optimization<ElementAllocator>(alloc)
             , clock(other.clock)
@@ -552,7 +554,10 @@ public:
 
     aged_ordered_container(aged_ordered_container&& other);
 
-    aged_ordered_container(aged_ordered_container&& other, Allocator const& alloc);
+    aged_ordered_container(
+        // NOLINTNEXTLINE(cppcoreguidelines-rvalue-reference-param-not-moved)
+        aged_ordered_container&& other,
+        Allocator const& alloc);
 
     aged_ordered_container(std::initializer_list<value_type> init, clock_type& clock);
 
@@ -1290,7 +1295,7 @@ aged_ordered_container<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::aged_
 
 template <bool IsMulti, bool IsMap, class Key, class T, class Clock, class Compare, class Allocator>
 aged_ordered_container<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::aged_ordered_container(
-    aged_ordered_container&& other,
+    aged_ordered_container&& other,  // NOLINT(cppcoreguidelines-rvalue-reference-param-not-moved)
     Allocator const& alloc)
     : m_config(std::move(other.m_config), alloc)
 #if BOOST_VERSION >= 108000

include/xrpl/beast/container/detail/aged_unordered_container.h

@@ -318,7 +318,9 @@ private:
         {
         }
 
-        config_t(config_t&& other, Allocator const& alloc)
+        config_t(
+            config_t&& other,  // NOLINT(cppcoreguidelines-rvalue-reference-param-not-moved)
+            Allocator const& alloc)
             : ValueHash(std::move(other.hash_function()))
             , KeyValueEqual(std::move(other.key_eq()))
             , beast::detail::empty_base_optimization<ElementAllocator>(alloc)
@@ -774,7 +776,10 @@ public:
 
     aged_unordered_container(aged_unordered_container&& other);
 
-    aged_unordered_container(aged_unordered_container&& other, Allocator const& alloc);
+    aged_unordered_container(
+        // NOLINTNEXTLINE(cppcoreguidelines-rvalue-reference-param-not-moved)
+        aged_unordered_container&& other,
+        Allocator const& alloc);
 
     aged_unordered_container(std::initializer_list<value_type> init, clock_type& clock);
 
@@ -1838,7 +1843,10 @@ template <
     class KeyEqual,
     class Allocator>
 aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
-    aged_unordered_container(aged_unordered_container&& other, Allocator const& alloc)
+    aged_unordered_container(
+        // NOLINTNEXTLINE(cppcoreguidelines-rvalue-reference-param-not-moved)
+        aged_unordered_container&& other,
+        Allocator const& alloc)
     : m_config(std::move(other.m_config), alloc)
     , m_buck(alloc)
     , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))

include/xrpl/beast/core/List.h

@@ -449,7 +449,7 @@ public:
     iterator
     erase(iterator pos) noexcept
     {
-        Node* node = &*pos;
+        Node const* node = &*pos;
         ++pos;
         node->m_next->m_prev = node->m_prev;
         node->m_prev->m_next = node->m_next;

include/xrpl/beast/core/LockFreeStack.h

@@ -187,7 +187,7 @@ public:
     bool
     push_front(Node* node)
     {
-        bool first;
+        bool first = false;
         Node* old_head = m_head.load(std::memory_order_relaxed);
         do
         {
@@ -211,7 +211,7 @@ public:
     pop_front()
     {
         Node* node = m_head.load();
-        Node* new_head;
+        Node* new_head = nullptr;
         do
         {
             if (node == &m_end)

include/xrpl/beast/hash/xxhasher.h

@@ -23,7 +23,7 @@ private:
     // A 64-byte buffer should to be big enough for us
     static constexpr std::size_t INTERNAL_BUFFER_SIZE = 64;
 
-    alignas(64) std::array<std::uint8_t, INTERNAL_BUFFER_SIZE> buffer_;
+    alignas(64) std::array<std::uint8_t, INTERNAL_BUFFER_SIZE> buffer_{};
     std::span<std::uint8_t> readBuffer_;
     std::span<std::uint8_t> writeBuffer_;
 

include/xrpl/beast/test/yield_to.h

@@ -114,7 +114,7 @@ enable_yield_to::spawn(F0&& f, FN&&... fn)
         boost::context::fixedsize_stack(2 * 1024 * 1024),
         [&](yield_context yield) {
             f(yield);
-            std::lock_guard lock{m_};
+            std::lock_guard const lock{m_};
             if (--running_ == 0)
                 cv_.notify_all();
         },

include/xrpl/beast/unit_test/results.h

@@ -35,10 +35,10 @@ private:
     class tests_t : public detail::const_container<std::vector<test>>
     {
     private:
-        std::size_t failed_;
+        std::size_t failed_{0};
 
     public:
-        tests_t() : failed_(0)
+        tests_t()
         {
         }
 
@@ -167,12 +167,12 @@ public:
 class results : public detail::const_container<std::vector<suite_results>>
 {
 private:
-    std::size_t m_cases;
-    std::size_t total_;
-    std::size_t failed_;
+    std::size_t m_cases{0};
+    std::size_t total_{0};
+    std::size_t failed_{0};
 
 public:
-    results() : m_cases(0), total_(0), failed_(0)
+    results()
     {
     }
 

include/xrpl/beast/unit_test/runner.h

@@ -228,7 +228,7 @@ template <class>
 void
 runner::testcase(std::string const& name)
 {
-    std::lock_guard lock(mutex_);
+    std::lock_guard const lock(mutex_);
     // Name may not be empty
     BOOST_ASSERT(default_ || !name.empty());
     // Forgot to call pass or fail
@@ -244,7 +244,7 @@ template <class>
 void
 runner::pass()
 {
-    std::lock_guard lock(mutex_);
+    std::lock_guard const lock(mutex_);
     if (default_)
         testcase("");
     on_pass();
@@ -255,7 +255,7 @@ template <class>
 void
 runner::fail(std::string const& reason)
 {
-    std::lock_guard lock(mutex_);
+    std::lock_guard const lock(mutex_);
     if (default_)
         testcase("");
     on_fail(reason);
@@ -267,7 +267,7 @@ template <class>
 void
 runner::log(std::string const& s)
 {
-    std::lock_guard lock(mutex_);
+    std::lock_guard const lock(mutex_);
     if (default_)
         testcase("");
     on_log(s);

include/xrpl/beast/unit_test/suite.h

@@ -300,7 +300,7 @@ private:
     static suite**
     p_this_suite()
     {
-        static suite* pts = nullptr;
+        static suite* pts = nullptr;  // NOLINT(misc-const-correctness)
         return &pts;
     }
 

include/xrpl/beast/utility/PropertyStream.h

@@ -311,7 +311,7 @@ private:
     std::string const m_name;
     std::recursive_mutex lock_;
     Item item_;
-    Source* parent_;
+    Source* parent_{nullptr};
     List<Item> children_;
 
 public:

include/xrpl/beast/utility/Zero.h

@@ -28,7 +28,7 @@ struct Zero
 
 namespace {
 static constexpr Zero zero{};
-}
+}  // namespace
 
 /** Default implementation of signum calls the method on the class. */
 template <typename T>

include/xrpl/beast/utility/instrumentation.h

@@ -15,7 +15,7 @@
 #define ALWAYS_OR_UNREACHABLE(cond, message) assert((message) && (cond))
 #define SOMETIMES(cond, message, ...)
 #define REACHABLE(message, ...)
-#define UNREACHABLE(message, ...) assert((message) && false)
+#define UNREACHABLE(message, ...) assert((message) && false)  // NOLINT(misc-static-assert)
 #endif
 
 #define XRPL_ASSERT ALWAYS_OR_UNREACHABLE

include/xrpl/beast/xor_shift_engine.h

@@ -37,7 +37,7 @@ public:
     }
 
 private:
-    result_type s_[2];
+    result_type s_[2]{};
 
     static result_type
     murmurhash3(result_type x);

include/xrpl/core/ClosureCounter.h

@@ -56,7 +56,7 @@ private:
         // a lock.  This removes a small timing window that occurs if the
         // waiting thread is handling a spurious wakeup when closureCount_
         // drops to zero.
-        std::lock_guard lock{mutex_};
+        std::lock_guard const lock{mutex_};
 
         // Update closureCount_.  Notify if stopping and closureCount_ == 0.
         if ((--closureCount_ == 0) && waitForClosures_)
@@ -92,7 +92,9 @@ private:
             ++counter_;
         }
 
-        Substitute(ClosureCounter& counter, Closure&& closure)
+        Substitute(
+            ClosureCounter& counter,
+            Closure&& closure)  // NOLINT(cppcoreguidelines-rvalue-reference-param-not-moved)
             : counter_(counter), closure_(std::forward<Closure>(closure))
         {
             ++counter_;
@@ -168,7 +170,7 @@ public:
     {
         std::optional<Substitute<Closure>> ret;
 
-        std::lock_guard lock{mutex_};
+        std::lock_guard const lock{mutex_};
         if (!waitForClosures_)
             ret.emplace(*this, std::forward<Closure>(closure));
 
@@ -191,7 +193,7 @@ public:
     bool
     joined() const
     {
-        std::lock_guard lock{mutex_};
+        std::lock_guard const lock{mutex_};
         return waitForClosures_;
     }
 };

include/xrpl/core/Coro.ipp

@@ -7,7 +7,6 @@ JobQueue::Coro::Coro(Coro_create_t, JobQueue& jq, JobType type, std::string cons
     : jq_(jq)
     , type_(type)
     , name_(name)
-    , running_(false)
     , coro_(
           // Stack size of 1MB wasn't sufficient for deep calls. ASAN tests flagged the issue. Hence
           // increasing the size to 1.5MB.
@@ -70,14 +69,24 @@ JobQueue::Coro::resume()
         running_ = true;
     }
     {
-        std::lock_guard lock(jq_.m_mutex);
+        std::lock_guard lk(jq_.m_mutex);
         --jq_.nSuspend_;
     }
     auto saved = detail::getLocalValues().release();
     detail::getLocalValues().reset(&lvs_);
     std::lock_guard lock(mutex_);
-    XRPL_ASSERT(static_cast<bool>(coro_), "xrpl::JobQueue::Coro::resume : is runnable");
-    coro_();
+    // A late resume() can arrive after the coroutine has already completed.
+    // This is an expected (if rare) outcome of the race condition documented
+    // in JobQueue.h:354-377 where post() schedules a resume job before the
+    // coroutine yields — the mutex serializes access, but by the time this
+    // resume() acquires the lock the coroutine may have already run to
+    // completion. Calling operator() on a completed boost::coroutine2 is
+    // undefined behavior, so we must check and skip invoking the coroutine
+    // body if it has already completed.
+    if (coro_)
+    {
+        coro_();
+    }
     detail::getLocalValues().release();
     detail::getLocalValues().reset(saved);
     std::lock_guard lk(mutex_run_);

include/xrpl/core/JobQueue.h

@@ -16,7 +16,7 @@ namespace xrpl {
 
 namespace perf {
 class PerfLog;
-}
+}  // namespace perf
 
 class Logs;
 struct Coro_create_t
@@ -45,7 +45,7 @@ public:
         JobQueue& jq_;
         JobType type_;
         std::string name_;
-        bool running_;
+        bool running_{false};
         std::mutex mutex_;
         std::mutex mutex_run_;
         std::condition_variable cv_;
@@ -99,8 +99,8 @@ public:
             Effects:
                The coroutine continues execution from where it last left off
                  using this same thread.
-            Undefined behavior if called after the coroutine has completed
-              with a return (as opposed to a yield()).
+               If the coroutine has already completed, returns immediately
+                 (handles the documented post-before-yield race condition).
             Undefined behavior if resume() or post() called consecutively
               without a corresponding yield.
         */
@@ -224,7 +224,7 @@ private:
 
     beast::Journal m_journal;
     mutable std::mutex m_mutex;
-    std::uint64_t m_lastJob;
+    std::uint64_t m_lastJob{0};
     std::set<Job> m_jobSet;
     JobCounter jobCounter_;
     std::atomic_bool stopping_{false};
@@ -233,7 +233,7 @@ private:
     JobTypeData m_invalidJobData;
 
     // The number of jobs currently in processTask()
-    int m_processCount;
+    int m_processCount{0};
 
     // The number of suspended coroutines
     int nSuspend_ = 0;
@@ -316,7 +316,7 @@ private:
     // Returns the limit of running jobs for the given job type.
     // For jobs with no limit, we return the largest int. Hopefully that
     // will be enough.
-    int
+    static int
     getJobLimit(JobType type);
 };
 
@@ -357,8 +357,10 @@ private:
     If the post() job were to be executed before yield(), undefined behavior
     would occur. The lock ensures that coro_ is not called again until we exit
     the coroutine. At which point a scheduled resume() job waiting on the lock
-    would gain entry, harmlessly call coro_ and immediately return as we have
-    already completed the coroutine.
+    would gain entry. resume() checks if the coroutine has already completed
+    (coro_ converts to false) and, if so, skips invoking operator() since
+    calling operator() on a completed boost::coroutine2 pull_type is undefined
+    behavior.
 
     The race condition occurs as follows:
 

include/xrpl/core/JobTypeData.h

@@ -19,13 +19,13 @@ public:
     JobTypeInfo const& info;
 
     /* The number of jobs waiting */
-    int waiting;
+    int waiting{0};
 
     /* The number presently running */
-    int running;
+    int running{0};
 
     /* And the number we deferred executing because of job limits */
-    int deferred;
+    int deferred{0};
 
     /* Notification callbacks */
     beast::insight::Event dequeue;
@@ -35,12 +35,8 @@ public:
         JobTypeInfo const& info_,
         beast::insight::Collector::ptr const& collector,
         Logs& logs) noexcept
-        : m_load(logs.journal("LoadMonitor"))
-        , m_collector(collector)
-        , info(info_)
-        , waiting(0)
-        , running(0)
-        , deferred(0)
+        : m_load(logs.journal("LoadMonitor")), m_collector(collector), info(info_)
+
     {
         m_load.setTargetLatency(info.getAverageLatency(), info.getPeakLatency());
 

include/xrpl/core/JobTypes.h

@@ -24,7 +24,7 @@ private:
               std::chrono::milliseconds{0})
     {
         using namespace std::chrono_literals;
-        int maxLimit = std::numeric_limits<int>::max();
+        int const maxLimit = std::numeric_limits<int>::max();
 
         auto add = [this](
                        JobType jt,

include/xrpl/core/LoadMonitor.h

@@ -36,10 +36,10 @@ public:
     {
         Stats();
 
-        std::uint64_t count;
+        std::uint64_t count{0};
         std::chrono::milliseconds latencyAvg;
         std::chrono::milliseconds latencyPeak;
-        bool isOverloaded;
+        bool isOverloaded{false};
     };
 
     Stats
@@ -54,8 +54,8 @@ private:
 
     std::mutex mutex_;
 
-    std::uint64_t mCounts;
-    int mLatencyEvents;
+    std::uint64_t mCounts{0};
+    int mLatencyEvents{0};
     std::chrono::milliseconds mLatencyMSAvg;
     std::chrono::milliseconds mLatencyMSPeak;
     std::chrono::milliseconds mTargetLatencyAvg;

include/xrpl/core/PeerReservationTable.h

@@ -67,7 +67,7 @@ public:
     bool
     contains(PublicKey const& nodeId)
     {
-        std::lock_guard lock(this->mutex_);
+        std::lock_guard const lock(this->mutex_);
         return table_.find({nodeId}) != table_.end();
     }
 
@@ -92,7 +92,7 @@ public:
 private:
     beast::Journal mutable journal_;
     std::mutex mutable mutex_;
-    DatabaseCon* connection_;
+    DatabaseCon* connection_{};
     std::unordered_set<PeerReservation, beast::uhash<>, KeyEqual> table_;
 };
 

include/xrpl/core/PerfLog.h

@@ -14,7 +14,7 @@
 
 namespace beast {
 class Journal;
-}
+}  // namespace beast
 
 namespace xrpl {
 class Application;

include/xrpl/core/ServiceRegistry.h

@@ -3,7 +3,6 @@
 #include <xrpl/basics/Blob.h>
 #include <xrpl/basics/SHAMapHash.h>
 #include <xrpl/basics/TaggedCache.h>
-#include <xrpl/ledger/CachedSLEs.h>
 
 #include <boost/asio.hpp>
 
@@ -12,17 +11,31 @@ namespace xrpl {
 // Forward declarations
 namespace NodeStore {
 class Database;
-}
+}  // namespace NodeStore
 namespace Resource {
 class Manager;
-}
+}  // namespace Resource
 namespace perf {
 class PerfLog;
-}
+}  // namespace perf
 
 // This is temporary until we migrate all code to use ServiceRegistry.
 class Application;
 
+template <
+    class Key,
+    class T,
+    bool IsKeyCache,
+    class SharedWeakUnionPointer,
+    class SharedPointerType,
+    class Hash,
+    class KeyEqual,
+    class Mutex>
+class TaggedCache;
+class STLedgerEntry;
+using SLE = STLedgerEntry;
+using CachedSLEs = TaggedCache<uint256, SLE const>;
+
 // Forward declarations
 class AcceptedLedger;
 class AmendmentTable;
@@ -45,7 +58,7 @@ class NetworkIDService;
 class OpenLedger;
 class OrderBookDB;
 class Overlay;
-class PathRequests;
+class PathRequestManager;
 class PeerReservationTable;
 class PendingSaves;
 class RelationalDatabase;
@@ -89,7 +102,7 @@ public:
     getNodeFamily() = 0;
 
     virtual TimeKeeper&
-    timeKeeper() = 0;
+    getTimeKeeper() = 0;
 
     virtual JobQueue&
     getJobQueue() = 0;
@@ -98,7 +111,7 @@ public:
     getTempNodeCache() = 0;
 
     virtual CachedSLEs&
-    cachedSLEs() = 0;
+    getCachedSLEs() = 0;
 
     virtual NetworkIDService&
     getNetworkIDService() = 0;
@@ -120,26 +133,26 @@ public:
     getValidations() = 0;
 
     virtual ValidatorList&
-    validators() = 0;
+    getValidators() = 0;
 
     virtual ValidatorSite&
-    validatorSites() = 0;
+    getValidatorSites() = 0;
 
     virtual ManifestCache&
-    validatorManifests() = 0;
+    getValidatorManifests() = 0;
 
     virtual ManifestCache&
-    publisherManifests() = 0;
+    getPublisherManifests() = 0;
 
     // Network services
     virtual Overlay&
-    overlay() = 0;
+    getOverlay() = 0;
 
     virtual Cluster&
-    cluster() = 0;
+    getCluster() = 0;
 
     virtual PeerReservationTable&
-    peerReservations() = 0;
+    getPeerReservations() = 0;
 
     virtual Resource::Manager&
     getResourceManager() = 0;
@@ -174,13 +187,13 @@ public:
     getLedgerReplayer() = 0;
 
     virtual PendingSaves&
-    pendingSaves() = 0;
+    getPendingSaves() = 0;
 
     virtual OpenLedger&
-    openLedger() = 0;
+    getOpenLedger() = 0;
 
     virtual OpenLedger const&
-    openLedger() const = 0;
+    getOpenLedger() const = 0;
 
     // Transaction and operation services
     virtual NetworkOPs&
@@ -195,8 +208,8 @@ public:
     virtual TxQ&
     getTxQ() = 0;
 
-    virtual PathRequests&
-    getPathRequests() = 0;
+    virtual PathRequestManager&
+    getPathRequestManager() = 0;
 
     // Server services
     virtual ServerHandler&
@@ -210,16 +223,16 @@ public:
     isStopping() const = 0;
 
     virtual beast::Journal
-    journal(std::string const& name) = 0;
+    getJournal(std::string const& name) = 0;
 
     virtual boost::asio::io_context&
     getIOContext() = 0;
 
     virtual Logs&
-    logs() = 0;
+    getLogs() = 0;
 
     virtual std::optional<uint256> const&
-    trapTxID() const = 0;
+    getTrapTxID() const = 0;
 
     /** Retrieve the "wallet database" */
     virtual DatabaseCon&
@@ -228,7 +241,7 @@ public:
     // Temporary: Get the underlying Application for functions that haven't
     // been migrated yet. This should be removed once all code is migrated.
     virtual Application&
-    app() = 0;
+    getApp() = 0;
 };
 
 }  // namespace xrpl

include/xrpl/core/StartUpType.h

@@ -5,7 +5,7 @@
 
 namespace xrpl {
 
-enum class StartUpType { FRESH, NORMAL, LOAD, LOAD_FILE, REPLAY, NETWORK };
+enum class StartUpType { Fresh, Normal, Load, LoadFile, Replay, Network };
 
 inline std::ostream&
 operator<<(std::ostream& os, StartUpType const& type)

include/xrpl/core/detail/Workers.h

@@ -13,7 +13,7 @@ namespace xrpl {
 
 namespace perf {
 class PerfLog;
-}
+}  // namespace perf
 
 /**
  * `Workers` is effectively a thread pool. The constructor takes a "callback"
@@ -183,8 +183,8 @@ private:
         std::thread thread_;
         std::mutex mutex_;
         std::condition_variable wakeup_;
-        int wakeCount_;  // how many times to un-pause
-        bool shouldExit_;
+        int wakeCount_{0};  // how many times to un-pause
+        bool shouldExit_{false};
     };
 
 private:
@@ -197,9 +197,9 @@ private:
     std::string m_threadNames;     // The name to give each thread
     std::condition_variable m_cv;  // signaled when all threads paused
     std::mutex m_mut;
-    bool m_allPaused;
+    bool m_allPaused{true};
     semaphore m_semaphore;                             // each pending task is 1 resource
-    int m_numberOfThreads;                             // how many we want active now
+    int m_numberOfThreads{0};                          // how many we want active now
     std::atomic<int> m_activeCount;                    // to know when all are paused
     std::atomic<int> m_pauseCount;                     // how many threads need to pause now
     std::atomic<int> m_runningTaskCount;               // how many calls to processTask() active

include/xrpl/core/detail/semaphore.h

@@ -55,7 +55,7 @@ public:
     void
     notify()
     {
-        std::lock_guard lock{m_mutex};
+        std::lock_guard const lock{m_mutex};
         ++m_count;
         m_cond.notify_one();
     }

include/xrpl/json/json_reader.h

@@ -103,9 +103,9 @@ private:
     public:
         explicit ErrorInfo() = default;
 
-        Token token_;
+        Token token_{};
         std::string message_;
-        Location extra_;
+        Location extra_{};
     };
 
     using Errors = std::deque<ErrorInfo>;
@@ -173,11 +173,11 @@ private:
     Nodes nodes_;
     Errors errors_;
     std::string document_;
-    Location begin_;
-    Location end_;
-    Location current_;
-    Location lastValueEnd_;
-    Value* lastValue_;
+    Location begin_{};
+    Location end_{};
+    Location current_{};
+    Location lastValueEnd_{};
+    Value* lastValue_{};
 };
 
 template <class BufferSequence>

include/xrpl/json/json_value.h

@@ -641,7 +641,7 @@ public:
     SelfType
     operator++(int)
     {
-        SelfType temp(*this);
+        SelfType const temp(*this);
         ++*this;
         return temp;
     }
@@ -649,7 +649,7 @@ public:
     SelfType
     operator--(int)
     {
-        SelfType temp(*this);
+        SelfType const temp(*this);
         --*this;
         return temp;
     }

include/xrpl/json/json_writer.h

@@ -106,8 +106,8 @@ private:
     ChildValues childValues_;
     std::string document_;
     std::string indentString_;
-    int rightMargin_;
-    int indentSize_;
+    int rightMargin_{74};
+    int indentSize_{3};
     bool addChildValues_{};
 };
 
@@ -171,9 +171,9 @@ private:
     using ChildValues = std::vector<std::string>;
 
     ChildValues childValues_;
-    std::ostream* document_;
+    std::ostream* document_{nullptr};
     std::string indentString_;
-    int rightMargin_;
+    int rightMargin_{74};
     std::string indentation_;
     bool addChildValues_{};
 };

include/xrpl/ledger/AmendmentTable.h

@@ -143,7 +143,7 @@ public:
         // Inject appropriate pseudo-transactions
         for (auto const& it : actions)
         {
-            STTx amendTx(ttAMENDMENT, [&it, seq = lastClosedLedger->seq() + 1](auto& obj) {
+            STTx const amendTx(ttAMENDMENT, [&it, seq = lastClosedLedger->seq() + 1](auto& obj) {
                 obj.setAccountID(sfAccount, AccountID());
                 obj.setFieldH256(sfAmendment, it.first);
                 obj.setFieldU32(sfLedgerSequence, seq);

include/xrpl/ledger/ApplyView.h

@@ -213,11 +213,60 @@ public:
     // Called when a credit is made to an account
     // This is required to support PaymentSandbox
     virtual void
-    creditHook(
+    creditHookIOU(
         AccountID const& from,
         AccountID const& to,
         STAmount const& amount,
         STAmount const& preCreditBalance)
+    {
+        XRPL_ASSERT(amount.holds<Issue>(), "creditHookIOU: amount is for Issue");
+    }
+
+    virtual void
+    creditHookMPT(
+        AccountID const& from,
+        AccountID const& to,
+        STAmount const& amount,
+        std::uint64_t preCreditBalanceHolder,
+        std::int64_t preCreditBalanceIssuer)
+    {
+        XRPL_ASSERT(amount.holds<MPTIssue>(), "creditHookMPT: amount is for MPTIssue");
+    }
+
+    /** Facilitate tracking of MPT sold by an issuer owning MPT sell offer.
+     * Unlike IOU, MPT doesn't have bi-directional relationship with an issuer,
+     * where a trustline limits an amount that can be issued to a holder.
+     * Consequently, the credit step (last MPTEndpointStep or
+     * BookStep buying MPT) might temporarily overflow OutstandingAmount.
+     * Limiting of a step's output amount in this case is delegated to
+     * the next step (in rev order). The next step always redeems when a holder
+     * account sells MPT (first MPTEndpointStep or BookStep selling MPT).
+     * In this case the holder account is only limited by the step's output
+     * and it's available funds since it's transferring the funds from one
+     * account to another account and doesn't change OutstandingAmount.
+     * This doesn't apply to an offer owned by an issuer.
+     * In this case the issuer sells or self debits and is increasing
+     * OutstandingAmount. Ability to issue is limited by the issuer
+     * originally available funds less already self sold MPT amounts (MPT sell
+     * offer).
+     * Consider an example:
+     * - GW creates MPT(USD) with 1,000USD MaximumAmount.
+     * - GW pays 950USD to A1.
+     * - A1 creates an offer 100XRP(buy)/100USD(sell).
+     * - GW creates an offer 100XRP(buy)/100USD(sell).
+     * - A2 pays 200USD to A3 with sendMax of 200XRP.
+     * Since the payment engine executes payments in reverse,
+     * OutstandingAmount overflows in MPTEndpointStep: 950 + 200 = 1,150USD.
+     * BookStep first consumes A1 offer. This reduces OutstandingAmount
+     * by 100USD: 1,150 - 100 = 1,050USD. GW offer can only be partially
+     * consumed because the initial available amount is 50USD = 1,000 - 950.
+     * BookStep limits it's output to 150USD. This in turn limits A3's send
+     * amount to 150XRP: A1 buys 100XRP and sells 100USD to A3. This doesn't
+     * change OutstandingAmount. GW buys 50XRP and sells 50USD to A3. This
+     * changes OutstandingAmount to 1,000USD.
+     */
+    virtual void
+    issuerSelfDebitHookMPT(MPTIssue const& issue, std::uint64_t amount, std::int64_t origBalance)
     {
     }
 

include/xrpl/ledger/CachedSLEs.h

@@ -6,4 +6,4 @@
 
 namespace xrpl {
 using CachedSLEs = TaggedCache<uint256, SLE const>;
-}
+}  // namespace xrpl

include/xrpl/ledger/CanonicalTXSet.h

@@ -0,0 +1,157 @@
+#pragma once
+
+#include <xrpl/basics/CountedObject.h>
+#include <xrpl/protocol/RippleLedgerHash.h>
+#include <xrpl/protocol/STTx.h>
+#include <xrpl/protocol/SeqProxy.h>
+
+namespace xrpl {
+
+/** Holds transactions which were deferred to the next pass of consensus.
+
+    "Canonical" refers to the order in which transactions are applied.
+
+    - Puts transactions from the same account in SeqProxy order
+
+*/
+// VFALCO TODO rename to SortedTxSet
+class CanonicalTXSet : public CountedObject<CanonicalTXSet>
+{
+private:
+    class Key
+    {
+    public:
+        Key(uint256 const& account, SeqProxy seqProx, uint256 const& id)
+            : account_(account), txId_(id), seqProxy_(seqProx)
+        {
+        }
+
+        friend bool
+        operator<(Key const& lhs, Key const& rhs);
+
+        inline friend bool
+        operator>(Key const& lhs, Key const& rhs)
+        {
+            return rhs < lhs;
+        }
+
+        inline friend bool
+        operator<=(Key const& lhs, Key const& rhs)
+        {
+            return !(lhs > rhs);
+        }
+
+        inline friend bool
+        operator>=(Key const& lhs, Key const& rhs)
+        {
+            return !(lhs < rhs);
+        }
+
+        inline friend bool
+        operator==(Key const& lhs, Key const& rhs)
+        {
+            return lhs.txId_ == rhs.txId_;
+        }
+
+        inline friend bool
+        operator!=(Key const& lhs, Key const& rhs)
+        {
+            return !(lhs == rhs);
+        }
+
+        uint256 const&
+        getAccount() const
+        {
+            return account_;
+        }
+
+        uint256 const&
+        getTXID() const
+        {
+            return txId_;
+        }
+
+    private:
+        uint256 account_;
+        uint256 txId_;
+        SeqProxy seqProxy_;
+    };
+
+    friend bool
+    operator<(Key const& lhs, Key const& rhs);
+
+    // Calculate the salted key for the given account
+    uint256
+    accountKey(AccountID const& account);
+
+public:
+    using const_iterator = std::map<Key, std::shared_ptr<STTx const>>::const_iterator;
+
+public:
+    explicit CanonicalTXSet(LedgerHash const& saltHash) : salt_(saltHash)
+    {
+    }
+
+    void
+    insert(std::shared_ptr<STTx const> const& txn);
+
+    // Pops the next transaction on account that follows seqProx in the
+    // sort order.  Normally called when a transaction is successfully
+    // applied to the open ledger so the next transaction can be resubmitted
+    // without waiting for ledger close.
+    //
+    // The return value is often null, when an account has no more
+    // transactions.
+    std::shared_ptr<STTx const>
+    popAcctTransaction(std::shared_ptr<STTx const> const& tx);
+
+    void
+    reset(LedgerHash const& salt)
+    {
+        salt_ = salt;
+        map_.clear();
+    }
+
+    const_iterator
+    erase(const_iterator const& it)
+    {
+        return map_.erase(it);
+    }
+
+    const_iterator
+    begin() const
+    {
+        return map_.begin();
+    }
+
+    const_iterator
+    end() const
+    {
+        return map_.end();
+    }
+
+    size_t
+    size() const
+    {
+        return map_.size();
+    }
+    bool
+    empty() const
+    {
+        return map_.empty();
+    }
+
+    uint256 const&
+    key() const
+    {
+        return salt_;
+    }
+
+private:
+    std::map<Key, std::shared_ptr<STTx const>> map_;
+
+    // Used to salt the accounts so people can't mine for low account numbers
+    uint256 salt_;
+};
+
+}  // namespace xrpl

include/xrpl/ledger/Ledger.h

@@ -0,0 +1,428 @@
+#pragma once
+
+#include <xrpl/basics/CountedObject.h>
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/ledger/CachedView.h>
+#include <xrpl/ledger/View.h>
+#include <xrpl/protocol/Fees.h>
+#include <xrpl/protocol/Indexes.h>
+#include <xrpl/protocol/Rules.h>
+#include <xrpl/protocol/STLedgerEntry.h>
+#include <xrpl/protocol/Serializer.h>
+#include <xrpl/protocol/TxMeta.h>
+#include <xrpl/shamap/SHAMap.h>
+
+namespace xrpl {
+
+class ServiceRegistry;
+class Job;
+class TransactionMaster;
+
+class SqliteStatement;
+
+struct create_genesis_t
+{
+    explicit create_genesis_t() = default;
+};
+extern create_genesis_t const create_genesis;
+
+/** Holds a ledger.
+
+    The ledger is composed of two SHAMaps. The state map holds all of the
+    ledger entries such as account roots and order books. The tx map holds
+    all of the transactions and associated metadata that made it into that
+    particular ledger. Most of the operations on a ledger are concerned
+    with the state map.
+
+    This can hold just the header, a partial set of data, or the entire set
+    of data. It all depends on what is in the corresponding SHAMap entry.
+    Various functions are provided to populate or depopulate the caches that
+    the object holds references to.
+
+    Ledgers are constructed as either mutable or immutable.
+
+    1) If you are the sole owner of a mutable ledger, you can do whatever you
+    want with no need for locks.
+
+    2) If you have an immutable ledger, you cannot ever change it, so no need
+    for locks.
+
+    3) Mutable ledgers cannot be shared.
+
+    @note Presented to clients as ReadView
+    @note Calls virtuals in the constructor, so marked as final
+*/
+class Ledger final : public std::enable_shared_from_this<Ledger>,
+                     public DigestAwareReadView,
+                     public TxsRawView,
+                     public CountedObject<Ledger>
+{
+public:
+    Ledger(Ledger const&) = delete;
+    Ledger&
+    operator=(Ledger const&) = delete;
+
+    Ledger(Ledger&&) = delete;
+    Ledger&
+    operator=(Ledger&&) = delete;
+
+    /** Create the Genesis ledger.
+
+        The Genesis ledger contains a single account whose
+        AccountID is generated with a Generator using the seed
+        computed from the string "masterpassphrase" and ordinal
+        zero.
+
+        The account has an XRP balance equal to the total amount
+        of XRP in the system. No more XRP than the amount which
+        starts in this account can ever exist, with amounts
+        used to pay fees being destroyed.
+
+        Amendments specified are enabled in the genesis ledger
+    */
+    Ledger(
+        create_genesis_t,
+        Rules const& rules,
+        Fees const& fees,
+        std::vector<uint256> const& amendments,
+        Family& family);
+
+    Ledger(LedgerHeader const& info, Rules const& rules, Family& family);
+
+    /** Used for ledgers loaded from JSON files
+
+        @param acquire If true, acquires the ledger if not found locally
+
+        @note The fees parameter provides default values, but setup() may
+              override them from the ledger state if fee-related SLEs exist.
+    */
+    Ledger(
+        LedgerHeader const& info,
+        bool& loaded,
+        bool acquire,
+        Rules const& rules,
+        Fees const& fees,
+        Family& family,
+        beast::Journal j);
+
+    /** Create a new ledger following a previous ledger
+
+        The ledger will have the sequence number that
+        follows previous, and have
+        parentCloseTime == previous.closeTime.
+    */
+    Ledger(Ledger const& previous, NetClock::time_point closeTime);
+
+    // used for database ledgers
+    Ledger(
+        std::uint32_t ledgerSeq,
+        NetClock::time_point closeTime,
+        Rules const& rules,
+        Fees const& fees,
+        Family& family);
+
+    ~Ledger() = default;
+
+    //
+    // ReadView
+    //
+
+    bool
+    open() const override
+    {
+        return false;
+    }
+
+    LedgerHeader const&
+    header() const override
+    {
+        return header_;
+    }
+
+    void
+    setLedgerInfo(LedgerHeader const& info)
+    {
+        header_ = info;
+    }
+
+    Fees const&
+    fees() const override
+    {
+        return fees_;
+    }
+
+    Rules const&
+    rules() const override
+    {
+        return rules_;
+    }
+
+    bool
+    exists(Keylet const& k) const override;
+
+    bool
+    exists(uint256 const& key) const;
+
+    std::optional<uint256>
+    succ(uint256 const& key, std::optional<uint256> const& last = std::nullopt) const override;
+
+    std::shared_ptr<SLE const>
+    read(Keylet const& k) const override;
+
+    std::unique_ptr<sles_type::iter_base>
+    slesBegin() const override;
+
+    std::unique_ptr<sles_type::iter_base>
+    slesEnd() const override;
+
+    std::unique_ptr<sles_type::iter_base>
+    slesUpperBound(uint256 const& key) const override;
+
+    std::unique_ptr<txs_type::iter_base>
+    txsBegin() const override;
+
+    std::unique_ptr<txs_type::iter_base>
+    txsEnd() const override;
+
+    bool
+    txExists(uint256 const& key) const override;
+
+    tx_type
+    txRead(key_type const& key) const override;
+
+    //
+    // DigestAwareReadView
+    //
+
+    std::optional<digest_type>
+    digest(key_type const& key) const override;
+
+    //
+    // RawView
+    //
+
+    void
+    rawErase(std::shared_ptr<SLE> const& sle) override;
+
+    void
+    rawInsert(std::shared_ptr<SLE> const& sle) override;
+
+    void
+    rawErase(uint256 const& key);
+
+    void
+    rawReplace(std::shared_ptr<SLE> const& sle) override;
+
+    void
+    rawDestroyXRP(XRPAmount const& fee) override
+    {
+        header_.drops -= fee;
+    }
+
+    //
+    // TxsRawView
+    //
+
+    void
+    rawTxInsert(
+        uint256 const& key,
+        std::shared_ptr<Serializer const> const& txn,
+        std::shared_ptr<Serializer const> const& metaData) override;
+
+    // Insert the transaction, and return the hash of the SHAMap leaf node
+    // holding the transaction. The hash can be used to fetch the transaction
+    // directly, instead of traversing the SHAMap
+    // @param key transaction ID
+    // @param txn transaction
+    // @param metaData transaction metadata
+    // @return hash of SHAMap leaf node that holds the transaction
+    uint256
+    rawTxInsertWithHash(
+        uint256 const& key,
+        std::shared_ptr<Serializer const> const& txn,
+        std::shared_ptr<Serializer const> const& metaData);
+
+    //--------------------------------------------------------------------------
+
+    void
+    setValidated() const
+    {
+        header_.validated = true;
+    }
+
+    void
+    setAccepted(
+        NetClock::time_point closeTime,
+        NetClock::duration closeResolution,
+        bool correctCloseTime);
+
+    void
+    setImmutable(bool rehash = true);
+
+    bool
+    isImmutable() const
+    {
+        return mImmutable;
+    }
+
+    /*  Mark this ledger as "should be full".
+
+        "Full" is metadata property of the ledger, it indicates
+        that the local server wants all the corresponding nodes
+        in durable storage.
+
+        This is marked `const` because it reflects metadata
+        and not data that is in common with other nodes on the
+        network.
+    */
+    void
+    setFull() const
+    {
+        txMap_.setFull();
+        txMap_.setLedgerSeq(header_.seq);
+        stateMap_.setFull();
+        stateMap_.setLedgerSeq(header_.seq);
+    }
+
+    void
+    setTotalDrops(std::uint64_t totDrops)
+    {
+        header_.drops = totDrops;
+    }
+
+    SHAMap const&
+    stateMap() const
+    {
+        return stateMap_;
+    }
+
+    SHAMap&
+    stateMap()
+    {
+        return stateMap_;
+    }
+
+    SHAMap const&
+    txMap() const
+    {
+        return txMap_;
+    }
+
+    SHAMap&
+    txMap()
+    {
+        return txMap_;
+    }
+
+    // returns false on error
+    bool
+    addSLE(SLE const& sle);
+
+    //--------------------------------------------------------------------------
+
+    void
+    updateSkipList();
+
+    bool
+    walkLedger(beast::Journal j, bool parallel = false) const;
+
+    bool
+    isSensible() const;
+
+    void
+    invariants() const;
+    void
+    unshare() const;
+
+    /**
+     * get Negative UNL validators' master public keys
+     *
+     * @return the public keys
+     */
+    hash_set<PublicKey>
+    negativeUNL() const;
+
+    /**
+     * get the to be disabled validator's master public key if any
+     *
+     * @return the public key if any
+     */
+    std::optional<PublicKey>
+    validatorToDisable() const;
+
+    /**
+     * get the to be re-enabled validator's master public key if any
+     *
+     * @return the public key if any
+     */
+    std::optional<PublicKey>
+    validatorToReEnable() const;
+
+    /**
+     * update the Negative UNL ledger component.
+     * @note must be called at and only at flag ledgers
+     *       must be called before applying UNLModify Tx
+     */
+    void
+    updateNegativeUNL();
+
+    /** Returns true if the ledger is a flag ledger */
+    bool
+    isFlagLedger() const;
+
+    /** Returns true if the ledger directly precedes a flag ledger */
+    bool
+    isVotingLedger() const;
+
+    std::shared_ptr<SLE>
+    peek(Keylet const& k) const;
+
+private:
+    class sles_iter_impl;
+    class txs_iter_impl;
+
+    bool
+    setup();
+
+    /** @brief Deserialize a SHAMapItem containing a single STTx.
+     *
+     * @param item The SHAMapItem to deserialize.
+     * @return A shared pointer to the deserialized transaction.
+     * @throw May throw on deserialization error.
+     */
+    static std::shared_ptr<STTx const>
+    deserializeTx(SHAMapItem const& item);
+
+    /** @brief Deserialize a SHAMapItem containing STTx + STObject metadata.
+     *
+     * The SHAMapItem must contain two variable length serialization objects.
+     *
+     * @param item The SHAMapItem to deserialize.
+     * @return A pair containing shared pointers to the deserialized transaction
+     *         and metadata.
+     * @throw May throw on deserialization error.
+     */
+    static std::pair<std::shared_ptr<STTx const>, std::shared_ptr<STObject const>>
+    deserializeTxPlusMeta(SHAMapItem const& item);
+
+    bool mImmutable;
+
+    // A SHAMap containing the transactions associated with this ledger.
+    SHAMap mutable txMap_;
+
+    // A SHAMap containing the state objects for this ledger.
+    SHAMap mutable stateMap_;
+
+    // Protects fee variables
+    std::mutex mutable mutex_;
+
+    Fees fees_;
+    Rules rules_;
+    LedgerHeader header_;
+    beast::Journal j_;
+};
+
+/** A ledger wrapped in a CachedView. */
+using CachedLedger = CachedView<Ledger>;
+
+}  // namespace xrpl

include/xrpl/ledger/LedgerTiming.h

@@ -0,0 +1,146 @@
+#pragma once
+
+#include <xrpl/basics/chrono.h>
+#include <xrpl/beast/utility/Journal.h>
+
+#include <chrono>
+
+namespace xrpl {
+
+/**  Possible ledger close time resolutions.
+
+    Values should not be duplicated.
+    @see getNextLedgerTimeResolution
+*/
+std::chrono::seconds constexpr ledgerPossibleTimeResolutions[] = {
+    std::chrono::seconds{10},
+    std::chrono::seconds{20},
+    std::chrono::seconds{30},
+    std::chrono::seconds{60},
+    std::chrono::seconds{90},
+    std::chrono::seconds{120}};
+
+//! Initial resolution of ledger close time.
+auto constexpr ledgerDefaultTimeResolution = ledgerPossibleTimeResolutions[2];
+
+//! Close time resolution in genesis ledger
+auto constexpr ledgerGenesisTimeResolution = ledgerPossibleTimeResolutions[0];
+
+//! How often we increase the close time resolution (in numbers of ledgers)
+auto constexpr increaseLedgerTimeResolutionEvery = 8;
+
+//! How often we decrease the close time resolution (in numbers of ledgers)
+auto constexpr decreaseLedgerTimeResolutionEvery = 1;
+
+/** Calculates the close time resolution for the specified ledger.
+
+    The XRPL protocol uses binning to represent time intervals using only one
+    timestamp. This allows servers to derive a common time for the next ledger,
+    without the need for perfectly synchronized clocks.
+    The time resolution (i.e. the size of the intervals) is adjusted dynamically
+    based on what happened in the last ledger, to try to avoid disagreements.
+
+    @param previousResolution the resolution used for the prior ledger
+    @param previousAgree whether consensus agreed on the close time of the prior
+    ledger
+    @param ledgerSeq the sequence number of the new ledger
+
+    @pre previousResolution must be a valid bin
+         from @ref ledgerPossibleTimeResolutions
+
+    @tparam Rep Type representing number of ticks in std::chrono::duration
+    @tparam Period An std::ratio representing tick period in
+                   std::chrono::duration
+    @tparam Seq Unsigned integer-like type corresponding to the ledger sequence
+                number. It should be comparable to 0 and support modular
+                division. Built-in and tagged_integers are supported.
+*/
+template <class Rep, class Period, class Seq>
+std::chrono::duration<Rep, Period>
+getNextLedgerTimeResolution(
+    std::chrono::duration<Rep, Period> previousResolution,
+    bool previousAgree,
+    Seq ledgerSeq)
+{
+    XRPL_ASSERT(ledgerSeq != Seq{0}, "xrpl::getNextLedgerTimeResolution : valid ledger sequence");
+
+    using namespace std::chrono;
+    // Find the current resolution:
+    auto iter = std::find(
+        std::begin(ledgerPossibleTimeResolutions),
+        std::end(ledgerPossibleTimeResolutions),
+        previousResolution);
+    XRPL_ASSERT(
+        iter != std::end(ledgerPossibleTimeResolutions),
+        "xrpl::getNextLedgerTimeResolution : found time resolution");
+
+    // This should never happen, but just as a precaution
+    if (iter == std::end(ledgerPossibleTimeResolutions))
+        return previousResolution;
+
+    // If we did not previously agree, we try to decrease the resolution to
+    // improve the chance that we will agree now.
+    if (!previousAgree && (ledgerSeq % Seq{decreaseLedgerTimeResolutionEvery} == Seq{0}))
+    {
+        if (++iter != std::end(ledgerPossibleTimeResolutions))
+            return *iter;
+    }
+
+    // If we previously agreed, we try to increase the resolution to determine
+    // if we can continue to agree.
+    if (previousAgree && (ledgerSeq % Seq{increaseLedgerTimeResolutionEvery} == Seq{0}))
+    {
+        if (iter-- != std::begin(ledgerPossibleTimeResolutions))
+            return *iter;
+    }
+
+    return previousResolution;
+}
+
+/** Calculates the close time for a ledger, given a close time resolution.
+
+    @param closeTime The time to be rounded
+    @param closeResolution The resolution
+    @return @b closeTime rounded to the nearest multiple of @b closeResolution.
+    Rounds up if @b closeTime is midway between multiples of @b closeResolution.
+*/
+template <class Clock, class Duration, class Rep, class Period>
+std::chrono::time_point<Clock, Duration>
+roundCloseTime(
+    std::chrono::time_point<Clock, Duration> closeTime,
+    std::chrono::duration<Rep, Period> closeResolution)
+{
+    using time_point = decltype(closeTime);
+    if (closeTime == time_point{})
+        return closeTime;
+
+    closeTime += (closeResolution / 2);
+    return closeTime - (closeTime.time_since_epoch() % closeResolution);
+}
+
+/** Calculate the effective ledger close time
+
+    After adjusting the ledger close time based on the current resolution, also
+    ensure it is sufficiently separated from the prior close time.
+
+    @param closeTime The raw ledger close time
+    @param resolution The current close time resolution
+    @param priorCloseTime The close time of the prior ledger
+*/
+template <class Clock, class Duration, class Rep, class Period>
+std::chrono::time_point<Clock, Duration>
+effCloseTime(
+    std::chrono::time_point<Clock, Duration> closeTime,
+    std::chrono::duration<Rep, Period> resolution,
+    std::chrono::time_point<Clock, Duration> priorCloseTime)
+{
+    using namespace std::chrono_literals;
+    using time_point = decltype(closeTime);
+
+    if (closeTime == time_point{})
+        return closeTime;
+
+    return std::max<time_point>(roundCloseTime(closeTime, resolution), (priorCloseTime + 1s));
+}
+
+}  // namespace xrpl

include/xrpl/ledger/OrderBookDB.h

@@ -3,8 +3,8 @@
 #include <xrpl/ledger/AcceptedLedgerTx.h>
 #include <xrpl/ledger/BookListeners.h>
 #include <xrpl/ledger/ReadView.h>
+#include <xrpl/protocol/Asset.h>
 #include <xrpl/protocol/Book.h>
-#include <xrpl/protocol/Issue.h>
 #include <xrpl/protocol/MultiApiJson.h>
 #include <xrpl/protocol/UintTypes.h>
 
@@ -53,39 +53,56 @@ public:
         issue. This is useful for pathfinding to find all possible next hops
         from a given currency.
 
-        @param issue The issue to search for
+        @param asset The asset to search for
         @param domain Optional domain restriction for the order book
         @return Vector of books that want this issue
     */
     virtual std::vector<Book>
-    getBooksByTakerPays(Issue const& issue, std::optional<Domain> const& domain = std::nullopt) = 0;
+    getBooksByTakerPays(Asset const& asset, std::optional<Domain> const& domain = std::nullopt) = 0;
 
     /** Get the count of order books that want a specific issue.
 
-        @param issue The issue to search for
+        @param asset The asset to search for
         @param domain Optional domain restriction for the order book
         @return Number of books that want this issue
     */
     virtual int
-    getBookSize(Issue const& issue, std::optional<Domain> const& domain = std::nullopt) = 0;
+    getBookSize(Asset const& asset, std::optional<Domain> const& domain = std::nullopt) = 0;
 
     /** Check if an order book to XRP exists for the given issue.
 
-        @param issue The issue to check
+        @param asset The asset to check
         @param domain Optional domain restriction for the order book
         @return true if a book from this issue to XRP exists
     */
     virtual bool
-    isBookToXRP(Issue const& issue, std::optional<Domain> domain = std::nullopt) = 0;
+    isBookToXRP(Asset const& asset, std::optional<Domain> const& domain = std::nullopt) = 0;
 
+    /**
+     * Process a transaction for order book tracking.
+     * @param ledger The ledger the transaction was applied to
+     * @param alTx The transaction to process
+     * @param jvObj The JSON object of the transaction
+     */
     virtual void
     processTxn(
         std::shared_ptr<ReadView const> const& ledger,
         AcceptedLedgerTx const& alTx,
         MultiApiJson const& jvObj) = 0;
 
+    /**
+     * Get the book listeners for a book.
+     * @param book The book to get the listeners for
+     * @return The book listeners for the book
+     */
     virtual BookListeners::pointer
     getBookListeners(Book const&) = 0;
+
+    /**
+     * Create a new book listeners for a book.
+     * @param book The book to create the listeners for
+     * @return The new book listeners for the book
+     */
     virtual BookListeners::pointer
     makeBookListeners(Book const&) = 0;
 };

include/xrpl/ledger/PaymentSandbox.h

@@ -15,10 +15,55 @@ namespace detail {
 //        into the PaymentSandbox class itself
 class DeferredCredits
 {
-public:
-    struct Adjustment
+private:
+    using KeyIOU = std::tuple<AccountID, AccountID, Currency>;
+    struct ValueIOU
     {
-        Adjustment(STAmount const& d, STAmount const& c, STAmount const& b)
+        explicit ValueIOU() = default;
+
+        STAmount lowAcctCredits;
+        STAmount highAcctCredits;
+        STAmount lowAcctOrigBalance;
+    };
+
+    struct HolderValueMPT
+    {
+        HolderValueMPT() = default;
+        // Debit to issuer
+        std::uint64_t debit = 0;
+        std::uint64_t origBalance = 0;
+    };
+
+    struct IssuerValueMPT
+    {
+        IssuerValueMPT() = default;
+        std::map<AccountID, HolderValueMPT> holders;
+        // Credit to holder
+        std::uint64_t credit = 0;
+        // OutstandingAmount might overflow when MPTs are credited to a holder.
+        // Consider A1 paying 100MPT to A2 and A1 already having maximum MPTs.
+        // Since the payment engine executes a payment in revers, A2 is
+        // credited first and OutstandingAmount is going to be equal
+        // to MaximumAmount + 100MPT. In the next step A1 redeems 100MPT
+        // to the issuer and OutstandingAmount balances out.
+        std::int64_t origBalance = 0;
+        // Self debit on offer selling MPT. Since the payment engine executes
+        // a payment in reverse, a crediting/buying step may overflow
+        // OutstandingAmount. A sell MPT offer owned by a holder can redeem any
+        // amount up to the offer's amount and holder's available funds,
+        // balancing out OutstandingAmount. But if the offer's owner is issuer
+        // then it issues more MPT. In this case the available amount to issue
+        // is the initial issuer's available amount less all offer sell amounts
+        // by the issuer. This is self-debit, where the offer's owner,
+        // issuer in this case, debits to self.
+        std::uint64_t selfDebit = 0;
+    };
+    using AdjustmentMPT = IssuerValueMPT;
+
+public:
+    struct AdjustmentIOU
+    {
+        AdjustmentIOU(STAmount const& d, STAmount const& c, STAmount const& b)
             : debits(d), credits(c), origBalance(b)
         {
         }
@@ -29,16 +74,30 @@ public:
 
     // Get the adjustments for the balance between main and other.
     // Returns the debits, credits and the original balance
-    std::optional<Adjustment>
-    adjustments(AccountID const& main, AccountID const& other, Currency const& currency) const;
+    std::optional<AdjustmentIOU>
+    adjustmentsIOU(AccountID const& main, AccountID const& other, Currency const& currency) const;
+
+    std::optional<AdjustmentMPT>
+    adjustmentsMPT(MPTID const& mptID) const;
 
     void
-    credit(
+    creditIOU(
         AccountID const& sender,
         AccountID const& receiver,
         STAmount const& amount,
         STAmount const& preCreditSenderBalance);
 
+    void
+    creditMPT(
+        AccountID const& sender,
+        AccountID const& receiver,
+        STAmount const& amount,
+        std::uint64_t preCreditBalanceHolder,
+        std::int64_t preCreditBalanceIssuer);
+
+    void
+    issuerSelfDebitMPT(MPTIssue const& issue, std::uint64_t amount, std::int64_t origBalance);
+
     void
     ownerCount(AccountID const& id, std::uint32_t cur, std::uint32_t next);
 
@@ -52,21 +111,11 @@ public:
     apply(DeferredCredits& to);
 
 private:
-    // lowAccount, highAccount
-    using Key = std::tuple<AccountID, AccountID, Currency>;
-    struct Value
-    {
-        explicit Value() = default;
+    static KeyIOU
+    makeKeyIOU(AccountID const& a1, AccountID const& a2, Currency const& currency);
 
-        STAmount lowAcctCredits;
-        STAmount highAcctCredits;
-        STAmount lowAcctOrigBalance;
-    };
-
-    static Key
-    makeKey(AccountID const& a1, AccountID const& a2, Currency const& c);
-
-    std::map<Key, Value> credits_;
+    std::map<KeyIOU, ValueIOU> creditsIOU_;
+    std::map<MPTID, IssuerValueMPT> creditsMPT_;
     std::map<AccountID, std::uint32_t> ownerCounts_;
 };
 
@@ -131,16 +180,35 @@ public:
     /** @} */
 
     STAmount
-    balanceHook(AccountID const& account, AccountID const& issuer, STAmount const& amount)
+    balanceHookIOU(AccountID const& account, AccountID const& issuer, STAmount const& amount)
         const override;
 
+    STAmount
+    balanceHookMPT(AccountID const& account, MPTIssue const& issue, std::int64_t amount)
+        const override;
+
+    STAmount
+    balanceHookSelfIssueMPT(MPTIssue const& issue, std::int64_t amount) const override;
+
     void
-    creditHook(
+    creditHookIOU(
         AccountID const& from,
         AccountID const& to,
         STAmount const& amount,
         STAmount const& preCreditBalance) override;
 
+    void
+    creditHookMPT(
+        AccountID const& from,
+        AccountID const& to,
+        STAmount const& amount,
+        std::uint64_t preCreditBalanceHolder,
+        std::int64_t preCreditBalanceIssuer) override;
+
+    void
+    issuerSelfDebitHookMPT(MPTIssue const& issue, std::uint64_t amount, std::int64_t origBalance)
+        override;
+
     void
     adjustOwnerCountHook(AccountID const& account, std::uint32_t cur, std::uint32_t next) override;
 

include/xrpl/ledger/PendingSaves.h

@@ -0,0 +1,126 @@
+#pragma once
+
+#include <xrpl/protocol/Protocol.h>
+
+#include <condition_variable>
+#include <map>
+#include <mutex>
+
+namespace xrpl {
+
+/** Keeps track of which ledgers haven't been fully saved.
+
+    During the ledger building process this collection will keep
+    track of those ledgers that are being built but have not yet
+    been completely written.
+*/
+class PendingSaves
+{
+private:
+    std::mutex mutable mutex_;
+    std::map<LedgerIndex, bool> map_;
+    std::condition_variable await_;
+
+public:
+    /** Start working on a ledger
+
+        This is called prior to updating the SQLite indexes.
+
+        @return 'true' if work should be done
+    */
+    bool
+    startWork(LedgerIndex seq)
+    {
+        std::lock_guard const lock(mutex_);
+
+        auto it = map_.find(seq);
+
+        if ((it == map_.end()) || it->second)
+        {
+            // Work done or another thread is doing it
+            return false;
+        }
+
+        it->second = true;
+        return true;
+    }
+
+    /** Finish working on a ledger
+
+        This is called after updating the SQLite indexes.
+        The tracking of the work in progress is removed and
+        threads awaiting completion are notified.
+    */
+    void
+    finishWork(LedgerIndex seq)
+    {
+        std::lock_guard const lock(mutex_);
+
+        map_.erase(seq);
+        await_.notify_all();
+    }
+
+    /** Return `true` if a ledger is in the progress of being saved. */
+    bool
+    pending(LedgerIndex seq)
+    {
+        std::lock_guard const lock(mutex_);
+        return map_.find(seq) != map_.end();
+    }
+
+    /** Check if a ledger should be dispatched
+
+        Called to determine whether work should be done or
+        dispatched. If work is already in progress and the
+        call is synchronous, wait for work to be completed.
+
+        @return 'true' if work should be done or dispatched
+    */
+    bool
+    shouldWork(LedgerIndex seq, bool isSynchronous)
+    {
+        std::unique_lock<std::mutex> lock(mutex_);
+        do
+        {
+            auto it = map_.find(seq);
+
+            if (it == map_.end())
+            {
+                map_.emplace(seq, false);
+                return true;
+            }
+
+            if (!isSynchronous)
+            {
+                // Already dispatched
+                return false;
+            }
+
+            if (!it->second)
+            {
+                // Scheduled, but not dispatched
+                return true;
+            }
+
+            // Already in progress, just need to wait
+            await_.wait(lock);
+
+        } while (true);
+    }
+
+    /** Get a snapshot of the pending saves
+
+        Each entry in the returned map corresponds to a ledger
+        that is in progress or dispatched. The boolean indicates
+        whether work is currently in progress.
+    */
+    std::map<LedgerIndex, bool>
+    getSnapshot() const
+    {
+        std::lock_guard const lock(mutex_);
+
+        return map_;
+    }
+};
+
+}  // namespace xrpl

include/xrpl/ledger/ReadView.h

@@ -148,15 +148,35 @@ public:
 
     // Accounts in a payment are not allowed to use assets acquired during that
     // payment. The PaymentSandbox tracks the debits, credits, and owner count
-    // changes that accounts make during a payment. `balanceHook` adjusts
+    // changes that accounts make during a payment. `balanceHookIOU` adjusts
     // balances so newly acquired assets are not counted toward the balance.
     // This is required to support PaymentSandbox.
     virtual STAmount
-    balanceHook(AccountID const& account, AccountID const& issuer, STAmount const& amount) const
+    balanceHookIOU(AccountID const& account, AccountID const& issuer, STAmount const& amount) const
     {
+        XRPL_ASSERT(amount.holds<Issue>(), "balanceHookIOU: amount is for Issue");
+
         return amount;
     }
 
+    // balanceHookMPT adjusts balances so newly acquired assets are not counted
+    // toward the balance.
+    virtual STAmount
+    balanceHookMPT(AccountID const& account, MPTIssue const& issue, std::int64_t amount) const
+    {
+        return STAmount{issue, amount};
+    }
+
+    // An offer owned by an issuer and selling MPT is limited by the issuer's
+    // funds available to issue, which are originally available funds less
+    // already self sold MPT amounts (MPT sell offer). This hook is used
+    // by issuerFundsToSelfIssue() function.
+    virtual STAmount
+    balanceHookSelfIssueMPT(MPTIssue const& issue, std::int64_t amount) const
+    {
+        return STAmount{issue, amount};
+    }
+
     // Accounts in a payment are not allowed to use assets acquired during that
     // payment. The PaymentSandbox tracks the debits, credits, and owner count
     // changes that accounts make during a payment. `ownerCountHook` adjusts the

include/xrpl/ledger/View.h

@@ -2,32 +2,28 @@
 
 #include <xrpl/beast/utility/Journal.h>
 #include <xrpl/ledger/ApplyView.h>
-#include <xrpl/ledger/OpenView.h>
 #include <xrpl/ledger/ReadView.h>
-#include <xrpl/ledger/helpers/AccountRootHelpers.h>
-#include <xrpl/ledger/helpers/DirectoryHelpers.h>
-#include <xrpl/ledger/helpers/MPTokenHelpers.h>
-#include <xrpl/ledger/helpers/OfferHelpers.h>
-#include <xrpl/ledger/helpers/RippleStateHelpers.h>
-#include <xrpl/ledger/helpers/TokenHelpers.h>
-#include <xrpl/ledger/helpers/VaultHelpers.h>
-#include <xrpl/protocol/Asset.h>
-#include <xrpl/protocol/Indexes.h>
 #include <xrpl/protocol/MPTIssue.h>
 #include <xrpl/protocol/Protocol.h>
-#include <xrpl/protocol/Rate.h>
 #include <xrpl/protocol/STLedgerEntry.h>
-#include <xrpl/protocol/STObject.h>
-#include <xrpl/protocol/Serializer.h>
+#include <xrpl/protocol/STTx.h>
 #include <xrpl/protocol/TER.h>
 
+#include <cstdint>
 #include <functional>
-#include <initializer_list>
 #include <map>
+#include <memory>
+#include <optional>
+#include <set>
 #include <utility>
 
 namespace xrpl {
 
+// Forward declarations for SLE wrappers
+template <typename ViewT>
+class AccountRoot;
+using RAccountRoot = AccountRoot<ReadView>;
+
 enum class SkipEntry : bool { No = false, Yes };
 
 //------------------------------------------------------------------------------
@@ -39,10 +35,10 @@ enum class SkipEntry : bool { No = false, Yes };
 /** Determines whether the given expiration time has passed.
 
     In the XRP Ledger, expiration times are defined as the number of whole
-    seconds after the "Ripple Epoch" which, for historical reasons, is set
+    seconds after the "XRPL epoch" which, for historical reasons, is set
     to January 1, 2000 (00:00 UTC).
 
-    This is like the way the Unix epoch works, except the Ripple Epoch is
+    This is like the way the Unix epoch works, except the XRPL epoch is
     precisely 946,684,800 seconds after the Unix Epoch.
 
     See https://xrpl.org/basic-data-types.html#specifying-time
@@ -72,8 +68,8 @@ isVaultPseudoAccountFrozen(
 isLPTokenFrozen(
     ReadView const& view,
     AccountID const& account,
-    Issue const& asset,
-    Issue const& asset2);
+    Asset const& asset,
+    Asset const& asset2);
 
 // Return the list of enabled amendments
 [[nodiscard]] std::set<uint256>
@@ -166,7 +162,7 @@ canWithdraw(
     ReadView const& view,
     AccountID const& from,
     AccountID const& to,
-    AccountRoot const& toWrapped,
+    RAccountRoot const& toWrapped,
     STAmount const& amount,
     bool hasDestinationTag);
 

include/xrpl/ledger/helpers/AMMHelpers.h

@@ -1,8 +1,13 @@
 #pragma once
 
+#include <xrpl/basics/Expected.h>
 #include <xrpl/basics/Log.h>
 #include <xrpl/basics/Number.h>
 #include <xrpl/beast/utility/Journal.h>
+#include <xrpl/ledger/ReadView.h>
+#include <xrpl/ledger/Sandbox.h>
+#include <xrpl/ledger/helpers/RippleStateHelpers.h>
+#include <xrpl/ledger/helpers/TokenHelpers.h>
 #include <xrpl/protocol/AMMCore.h>
 #include <xrpl/protocol/AmountConversions.h>
 #include <xrpl/protocol/Feature.h>
@@ -11,6 +16,7 @@
 #include <xrpl/protocol/Quality.h>
 #include <xrpl/protocol/Rules.h>
 #include <xrpl/protocol/STAmount.h>
+#include <xrpl/protocol/STLedgerEntry.h>
 
 namespace xrpl {
 
@@ -22,7 +28,7 @@ reduceOffer(auto const& amount)
     static Number const reducedOfferPct(9999, -4);
 
     // Make sure the result is always less than amount or zero.
-    NumberRoundModeGuard mg(Number::towards_zero);
+    NumberRoundModeGuard const mg(Number::towards_zero);
     return amount * reducedOfferPct;
 }
 
@@ -36,7 +42,7 @@ enum class IsDeposit : bool { No = false, Yes = true };
  * @return LP Tokens as IOU
  */
 STAmount
-ammLPTokens(STAmount const& asset1, STAmount const& asset2, Issue const& lptIssue);
+ammLPTokens(STAmount const& asset1, STAmount const& asset2, Asset const& lptIssue);
 
 /** Calculate LP Tokens given asset's deposit amount.
  * @param asset1Balance current AMM asset1 balance
@@ -121,11 +127,11 @@ withinRelativeDistance(Quality const& calcQuality, Quality const& reqQuality, Nu
  * @param dist requested relative distance
  * @return true if within dist, false otherwise
  */
-// clang-format off
 template <typename Amt>
     requires(
         std::is_same_v<Amt, STAmount> || std::is_same_v<Amt, IOUAmount> ||
-        std::is_same_v<Amt, XRPAmount> || std::is_same_v<Amt, Number>)
+        std::is_same_v<Amt, XRPAmount> || std::is_same_v<Amt, MPTAmount> ||
+        std::is_same_v<Amt, Number>)
 bool
 withinRelativeDistance(Amt const& calc, Amt const& req, Number const& dist)
 {
@@ -134,7 +140,6 @@ withinRelativeDistance(Amt const& calc, Amt const& req, Number const& dist)
     auto const [min, max] = std::minmax(calc, req);
     return ((max - min) / max) < dist;
 }
-// clang-format on
 
 /** Solve quadratic equation to find takerGets or takerPays. Round
  * to minimize the amount in order to maximize the quality.
@@ -175,7 +180,7 @@ getAMMOfferStartWithTakerGets(
     if (targetQuality.rate() == beast::zero)
         return std::nullopt;
 
-    NumberRoundModeGuard mg(Number::to_nearest);
+    NumberRoundModeGuard const mg(Number::to_nearest);
     auto const f = feeMult(tfee);
     auto const a = 1;
     auto const b = pool.in * (1 - 1 / f) / targetQuality.rate() - 2 * pool.out;
@@ -197,13 +202,13 @@ getAMMOfferStartWithTakerGets(
         // Round downward to minimize the offer and to maximize the quality.
         // This has the most impact when takerGets is XRP.
         auto const takerGets =
-            toAmount<TOut>(getIssue(pool.out), nTakerGetsProposed, Number::downward);
+            toAmount<TOut>(getAsset(pool.out), nTakerGetsProposed, Number::downward);
         return TAmounts<TIn, TOut>{swapAssetOut(pool, takerGets, tfee), takerGets};
     };
 
     // Try to reduce the offer size to improve the quality.
     // The quality might still not match the targetQuality for a tiny offer.
-    if (auto const amounts = getAmounts(*nTakerGets); Quality{amounts} < targetQuality)
+    if (auto amounts = getAmounts(*nTakerGets); Quality{amounts} < targetQuality)
         return getAmounts(detail::reduceOffer(amounts.out));
     else
         return amounts;
@@ -242,7 +247,7 @@ getAMMOfferStartWithTakerPays(
     if (targetQuality.rate() == beast::zero)
         return std::nullopt;
 
-    NumberRoundModeGuard mg(Number::to_nearest);
+    NumberRoundModeGuard const mg(Number::to_nearest);
     auto const f = feeMult(tfee);
     auto const& a = f;
     auto const b = pool.in * (1 + f);
@@ -264,13 +269,13 @@ getAMMOfferStartWithTakerPays(
         // Round downward to minimize the offer and to maximize the quality.
         // This has the most impact when takerPays is XRP.
         auto const takerPays =
-            toAmount<TIn>(getIssue(pool.in), nTakerPaysProposed, Number::downward);
+            toAmount<TIn>(getAsset(pool.in), nTakerPaysProposed, Number::downward);
         return TAmounts<TIn, TOut>{takerPays, swapAssetIn(pool, takerPays, tfee)};
     };
 
     // Try to reduce the offer size to improve the quality.
     // The quality might still not match the targetQuality for a tiny offer.
-    if (auto const amounts = getAmounts(*nTakerPays); Quality{amounts} < targetQuality)
+    if (auto amounts = getAmounts(*nTakerPays); Quality{amounts} < targetQuality)
         return getAmounts(detail::reduceOffer(amounts.in));
     else
         return amounts;
@@ -333,10 +338,9 @@ changeSpotPriceQuality(
                                 << " " << to_string(pool.out) << " " << quality << " " << tfee;
                 return std::nullopt;
             }
-            auto const takerPays = toAmount<TIn>(getIssue(pool.in), nTakerPays, Number::upward);
+            auto const takerPays = toAmount<TIn>(getAsset(pool.in), nTakerPays, Number::upward);
             // should not fail
-            if (auto const amounts =
-                    TAmounts<TIn, TOut>{takerPays, swapAssetIn(pool, takerPays, tfee)};
+            if (auto amounts = TAmounts<TIn, TOut>{takerPays, swapAssetIn(pool, takerPays, tfee)};
                 Quality{amounts} < quality &&
                 !withinRelativeDistance(Quality{amounts}, quality, Number(1, -7)))
             {
@@ -362,8 +366,8 @@ changeSpotPriceQuality(
 
     // Generate the offer starting with XRP side. Return seated offer amounts
     // if the offer can be generated, otherwise nullopt.
-    auto const amounts = [&]() {
-        if (isXRP(getIssue(pool.out)))
+    auto amounts = [&]() {
+        if (isXRP(getAsset(pool.out)))
             return getAMMOfferStartWithTakerGets(pool, quality, tfee);
         return getAMMOfferStartWithTakerPays(pool, quality, tfee);
     }();
@@ -438,7 +442,7 @@ swapAssetIn(TAmounts<TIn, TOut> const& pool, TIn const& assetIn, std::uint16_t t
         // 1-fee
         // maximize:
         // fee
-        saveNumberRoundMode _{Number::getround()};
+        saveNumberRoundMode const _{Number::getround()};
 
         Number::setround(Number::upward);
         auto const numerator = pool.in * pool.out;
@@ -448,7 +452,7 @@ swapAssetIn(TAmounts<TIn, TOut> const& pool, TIn const& assetIn, std::uint16_t t
         auto const denom = pool.in + assetIn * (1 - fee);
 
         if (denom.signum() <= 0)
-            return toAmount<TOut>(getIssue(pool.out), 0);
+            return toAmount<TOut>(getAsset(pool.out), 0);
 
         Number::setround(Number::upward);
         auto const ratio = numerator / denom;
@@ -457,14 +461,14 @@ swapAssetIn(TAmounts<TIn, TOut> const& pool, TIn const& assetIn, std::uint16_t t
         auto const swapOut = pool.out - ratio;
 
         if (swapOut.signum() < 0)
-            return toAmount<TOut>(getIssue(pool.out), 0);
+            return toAmount<TOut>(getAsset(pool.out), 0);
 
-        return toAmount<TOut>(getIssue(pool.out), swapOut, Number::downward);
+        return toAmount<TOut>(getAsset(pool.out), swapOut, Number::downward);
     }
     else
     {
         return toAmount<TOut>(
-            getIssue(pool.out),
+            getAsset(pool.out),
             pool.out - (pool.in * pool.out) / (pool.in + assetIn * feeMult(tfee)),
             Number::downward);
     }
@@ -502,7 +506,7 @@ swapAssetOut(TAmounts<TIn, TOut> const& pool, TOut const& assetOut, std::uint16_
         // maximize:
         // tfee/100000
 
-        saveNumberRoundMode _{Number::getround()};
+        saveNumberRoundMode const _{Number::getround()};
 
         Number::setround(Number::upward);
         auto const numerator = pool.in * pool.out;
@@ -511,7 +515,7 @@ swapAssetOut(TAmounts<TIn, TOut> const& pool, TOut const& assetOut, std::uint16_
         auto const denom = pool.out - assetOut;
         if (denom.signum() <= 0)
         {
-            return toMaxAmount<TIn>(getIssue(pool.in));
+            return toMaxAmount<TIn>(getAsset(pool.in));
         }
 
         Number::setround(Number::upward);
@@ -525,14 +529,14 @@ swapAssetOut(TAmounts<TIn, TOut> const& pool, TOut const& assetOut, std::uint16_
         Number::setround(Number::upward);
         auto const swapIn = numerator2 / feeMult;
         if (swapIn.signum() < 0)
-            return toAmount<TIn>(getIssue(pool.in), 0);
+            return toAmount<TIn>(getAsset(pool.in), 0);
 
-        return toAmount<TIn>(getIssue(pool.in), swapIn, Number::upward);
+        return toAmount<TIn>(getAsset(pool.in), swapIn, Number::upward);
     }
     else
     {
         return toAmount<TIn>(
-            getIssue(pool.in),
+            getAsset(pool.in),
             ((pool.in * pool.out) / (pool.out - assetOut) - pool.in) / feeMult(tfee),
             Number::upward);
     }
@@ -619,9 +623,9 @@ getRoundedAsset(Rules const& rules, STAmount const& balance, A const& frac, IsDe
     if (!rules.enabled(fixAMMv1_3))
     {
         if constexpr (std::is_same_v<A, STAmount>)
-            return multiply(balance, frac, balance.issue());
+            return multiply(balance, frac, balance.asset());
         else
-            return toSTAmount(balance.issue(), balance * frac);
+            return toSTAmount(balance.asset(), balance * frac);
     }
     auto const rm = detail::getAssetRounding(isDeposit);
     return multiply(balance, frac, rm);
@@ -715,4 +719,94 @@ adjustFracByTokens(
     STAmount const& tokens,
     Number const& frac);
 
+/** Get AMM pool balances.
+ */
+std::pair<STAmount, STAmount>
+ammPoolHolds(
+    ReadView const& view,
+    AccountID const& ammAccountID,
+    Asset const& asset1,
+    Asset const& asset2,
+    FreezeHandling freezeHandling,
+    AuthHandling authHandling,
+    beast::Journal const j);
+
+/** Get AMM pool and LP token balances. If both optIssue are
+ * provided then they are used as the AMM token pair issues.
+ * Otherwise the missing issues are fetched from ammSle.
+ */
+Expected<std::tuple<STAmount, STAmount, STAmount>, TER>
+ammHolds(
+    ReadView const& view,
+    SLE const& ammSle,
+    std::optional<Asset> const& optAsset1,
+    std::optional<Asset> const& optAsset2,
+    FreezeHandling freezeHandling,
+    AuthHandling authHandling,
+    beast::Journal const j);
+
+/** Get the balance of LP tokens.
+ */
+STAmount
+ammLPHolds(
+    ReadView const& view,
+    Asset const& asset1,
+    Asset const& asset2,
+    AccountID const& ammAccount,
+    AccountID const& lpAccount,
+    beast::Journal const j);
+
+STAmount
+ammLPHolds(
+    ReadView const& view,
+    SLE const& ammSle,
+    AccountID const& lpAccount,
+    beast::Journal const j);
+
+/** Get AMM trading fee for the given account. The fee is discounted
+ * if the account is the auction slot owner or one of the slot's authorized
+ * accounts.
+ */
+std::uint16_t
+getTradingFee(ReadView const& view, SLE const& ammSle, AccountID const& account);
+
+/** Returns total amount held by AMM for the given token.
+ */
+STAmount
+ammAccountHolds(ReadView const& view, AccountID const& ammAccountID, Asset const& asset);
+
+/** Delete trustlines to AMM. If all trustlines are deleted then
+ * AMM object and account are deleted. Otherwise tecINCOMPLETE is returned.
+ */
+TER
+deleteAMMAccount(Sandbox& view, Asset const& asset, Asset const& asset2, beast::Journal j);
+
+/** Initialize Auction and Voting slots and set the trading/discounted fee.
+ */
+void
+initializeFeeAuctionVote(
+    ApplyView& view,
+    std::shared_ptr<SLE>& ammSle,
+    AccountID const& account,
+    Asset const& lptAsset,
+    std::uint16_t tfee);
+
+/** Return true if the Liquidity Provider is the only AMM provider, false
+ * otherwise. Return tecINTERNAL if encountered an unexpected condition,
+ * for instance Liquidity Provider has more than one LPToken trustline.
+ */
+Expected<bool, TER>
+isOnlyLiquidityProvider(ReadView const& view, Issue const& ammIssue, AccountID const& lpAccount);
+
+/** Due to rounding, the LPTokenBalance of the last LP might
+ * not match the LP's trustline balance. If it's within the tolerance,
+ * update LPTokenBalance to match the LP's trustline balance.
+ */
+Expected<bool, TER>
+verifyAndAdjustLPTokenBalance(
+    Sandbox& sb,
+    STAmount const& lpTokens,
+    std::shared_ptr<SLE>& ammSle,
+    AccountID const& account);
+
 }  // namespace xrpl

include/xrpl/ledger/helpers/AccountRootHelpers.h

@@ -18,27 +18,68 @@
 namespace xrpl {
 
 /**
- * Read-only wrapper for AccountRoot ledger entries.
+ * View-parameterized wrapper for AccountRoot ledger entries.
  *
- * Provides read-only access to account data.
+ * AccountRoot<ReadView>  — read-only access to account data
+ * AccountRoot<ApplyView> — read-write access, with insert/update/erase
+ *                          and domain-specific write methods
  */
-class AccountRoot : public ReadOnlySLE
+template <typename ViewT>
+class AccountRoot : public SLEBase<ViewT>
 {
-protected:
+    static constexpr bool is_writable = SLEBase<ViewT>::is_writable;
+
     AccountID const id_;
 
 public:
-    AccountRoot(AccountID const& id, ReadView const& view)
-        : ReadOnlySLE(view.read(keylet::account(id)), view), id_(id)
+    /** Constructor for read-only context */
+    AccountRoot(
+        AccountID const& id,
+        ReadView const& view,
+        beast::Journal j = beast::Journal{beast::Journal::getNullSink()})
+        requires(!is_writable)
+        : SLEBase<ViewT>(view.read(keylet::account(id)), view, j), id_(id)
     {
     }
 
+    /** Constructor for writable context */
+    AccountRoot(
+        AccountID const& id,
+        ApplyView& view,
+        beast::Journal j = beast::Journal{beast::Journal::getNullSink()})
+        requires is_writable
+        : SLEBase<ViewT>(keylet::account(id), view, j), id_(id)
+    {
+    }
+
+    /** Converting constructor: writable → read-only. */
+    template <WritableView OtherViewT>
+    AccountRoot(AccountRoot<OtherViewT> const& other)
+        requires(!is_writable)
+        : SLEBase<ViewT>(other), id_(other.id())
+    {
+    }
+
+    /** Create an AccountRoot backed by a brand-new SLE.
+     */
+    [[nodiscard]] static AccountRoot
+    makeNew(
+        AccountID const& id,
+        ApplyView& view,
+        beast::Journal j = beast::Journal{beast::Journal::getNullSink()})
+        requires is_writable
+    {
+        return AccountRoot(id, view, j, std::make_shared<SLE>(keylet::account(id)));
+    }
+
     AccountID const&
     id() const
     {
         return id_;
     }
 
+    // --- Read-only domain methods (available on both specializations) ---
+
     /** Check if the issuer has the global freeze flag set.
         @return true if the account has global freeze set
     */
@@ -62,7 +103,7 @@ public:
     //
     // @param ownerCountAdj positive to add to count, negative to reduce count.
     [[nodiscard]] XRPAmount
-    xrpLiquid(std::int32_t ownerCountAdj, beast::Journal j) const;
+    xrpLiquid(std::int32_t ownerCountAdj) const;
 
     /** Checks the destination and tag.
 
@@ -94,57 +135,42 @@ public:
     {
         return id_ == other;
     }
-};
 
-/**
- * Writable wrapper for AccountRoot ledger entries.
- *
- * Provides read-write access to account data.
- * Inherits from AccountRoot to reuse read-only methods,
- * and adds write capabilities.
- */
-class WritableAccountRoot : public AccountRoot, public WritableSLE
-{
-public:
-    WritableAccountRoot(AccountID const& id, ApplyView& view)
-        : AccountRoot(id, view), WritableSLE(keylet::account(id), view)
-    {
-    }
-
-    /** Create a WritableAccountRoot backed by a brand-new SLE
-     *  (not yet inserted into the view).
-     */
-    [[nodiscard]] static WritableAccountRoot
-    makeNew(AccountID const& id, ApplyView& view)
-    {
-        return WritableAccountRoot(id, view, std::make_shared<SLE>(keylet::account(id)));
-    }
-
-private:
-    // This is a private constructor only used by `makeNew`
-    WritableAccountRoot(AccountID const& id, ApplyView& view, std::shared_ptr<SLE> sle)
-        : AccountRoot(id, view), WritableSLE(std::move(sle), view)
-    {
-        insert();
-    }
-
-public:
-    // Resolve ambiguity: use writable operator-> for non-const, read-only for const
-    using WritableSLE::operator->;
-    using AccountRoot::operator->;
-    using WritableSLE::operator*;
-    using AccountRoot::operator*;
+    // --- Write-only domain methods (compile-time gated) ---
 
     /** Adjust the owner count up or down. */
     void
-    adjustOwnerCount(std::int32_t amount, beast::Journal j);
+    adjustOwnerCount(std::int32_t amount)
+        requires is_writable;
+
+private:
+    // Private constructor only used by `makeNew`
+    AccountRoot(AccountID const& id, ApplyView& view, beast::Journal j, std::shared_ptr<SLE> sle)
+        requires is_writable
+        : SLEBase<ViewT>(std::move(sle), view, j), id_(id)
+    {
+        this->insert();
+    }
 };
 
+// CTAD deduction guide — bare AccountRoot(id, view) always deduces read-only.
+// For writable access, use WAccountRoot(id, applyView) explicitly.
+AccountRoot(AccountID const&, ReadView const&) -> AccountRoot<ReadView>;
+AccountRoot(AccountID const&, ReadView const&, beast::Journal) -> AccountRoot<ReadView>;
+
+// Backward-compatible aliases
+using RAccountRoot = AccountRoot<ReadView>;
+using WAccountRoot = AccountRoot<ApplyView>;
+
+// Explicit instantiation declarations (definitions in .cpp)
+extern template class AccountRoot<ReadView>;
+extern template class AccountRoot<ApplyView>;
+
 /** Generate a pseudo-account address from a pseudo owner key.
     @param pseudoOwnerKey The key to generate the address from
     @return The generated account ID
 */
-AccountID
+[[nodiscard]] AccountID
 pseudoAccountAddress(ReadView const& view, uint256 const& pseudoOwnerKey);
 
 /** Returns the list of fields that define an ACCOUNT_ROOT as a pseudo-account
@@ -157,32 +183,6 @@ pseudoAccountAddress(ReadView const& view, uint256 const& pseudoOwnerKey);
 [[nodiscard]] std::vector<SField const*> const&
 getPseudoAccountFields();
 
-/** Returns true if and only if sleAcct is a pseudo-account or specific
-    pseudo-accounts in pseudoFieldFilter.
-
-    Returns false if sleAcct is:
-    - NOT a pseudo-account OR
-    - NOT a ltACCOUNT_ROOT OR
-    - null pointer
-*/
-[[nodiscard]] bool
-isPseudoAccount(
-    std::shared_ptr<SLE const> sleAcct,
-    std::set<SField const*> const& pseudoFieldFilter = {});
-
-/** Convenience overload that reads the account from the view. */
-[[nodiscard]] inline bool
-isPseudoAccount(
-    ReadView const& view,
-    AccountID const& accountId,
-    std::set<SField const*> const& pseudoFieldFilter = {})
-{
-    AccountRoot const acct(accountId, view);
-    if (!acct)
-        return false;
-    return acct.isPseudoAccount(pseudoFieldFilter);
-}
-
 /**
  * Create pseudo-account, storing pseudoOwnerKey into ownerField.
  *

include/xrpl/ledger/helpers/CredentialHelpers.h

@@ -74,7 +74,7 @@ verifyDepositPreauth(
     STTx const& tx,
     ApplyView& view,
     AccountID const& src,
-    AccountRoot const& dst,
+    RAccountRoot const& dst,
     beast::Journal j);
 
 }  // namespace xrpl

include/xrpl/ledger/helpers/EscrowHelpers.h

@@ -0,0 +1,244 @@
+#pragma once
+
+#include <xrpl/basics/Log.h>
+#include <xrpl/ledger/ApplyView.h>
+#include <xrpl/ledger/View.h>
+#include <xrpl/ledger/helpers/AccountRootHelpers.h>
+#include <xrpl/ledger/helpers/MPTokenHelpers.h>
+#include <xrpl/ledger/helpers/RippleStateHelpers.h>
+#include <xrpl/protocol/Feature.h>
+#include <xrpl/protocol/Indexes.h>
+#include <xrpl/protocol/MPTAmount.h>
+#include <xrpl/protocol/Rate.h>
+
+#include <variant>
+
+namespace xrpl {
+
+template <ValidIssueType T>
+TER
+escrowUnlockApplyHelper(
+    ApplyView& view,
+    Rate lockedRate,
+    std::variant<std::shared_ptr<SLE>, WAccountRoot> dest,
+    STAmount const& xrpBalance,
+    STAmount const& amount,
+    AccountID const& issuer,
+    AccountID const& sender,
+    AccountID const& receiver,
+    bool createAsset,
+    beast::Journal journal);
+
+template <>
+inline TER
+escrowUnlockApplyHelper<Issue>(
+    ApplyView& view,
+    Rate lockedRate,
+    std::variant<std::shared_ptr<SLE>, WAccountRoot> dest,
+    STAmount const& xrpBalance,
+    STAmount const& amount,
+    AccountID const& issuer,
+    AccountID const& sender,
+    AccountID const& receiver,
+    bool createAsset,
+    beast::Journal journal)
+{
+    Issue const& issue = amount.get<Issue>();
+    Keylet const trustLineKey = keylet::line(receiver, issue);
+    bool const recvLow = issuer > receiver;
+    bool const senderIssuer = issuer == sender;
+    bool const receiverIssuer = issuer == receiver;
+
+    if (senderIssuer)
+        return tecINTERNAL;  // LCOV_EXCL_LINE
+
+    if (receiverIssuer)
+        return tesSUCCESS;
+
+    if (!view.exists(trustLineKey) && createAsset)
+    {
+        // For backwards compatibility: if dest is not WAccountRoot, return error
+        if (!std::holds_alternative<WAccountRoot>(dest))
+            return tefEXCEPTION;
+
+        auto& wrappedDest = std::get<WAccountRoot>(dest);
+
+        // Can the account cover the trust line's reserve?
+        if (std::uint32_t const ownerCount = {wrappedDest->at(sfOwnerCount)};
+            xrpBalance < view.fees().accountReserve(ownerCount + 1))
+        {
+            JLOG(journal.trace()) << "Trust line does not exist. "
+                                     "Insufficient reserve to create line.";
+
+            return tecNO_LINE_INSUF_RESERVE;
+        }
+
+        Currency const currency = issue.currency;
+        STAmount initialBalance(issue);
+        initialBalance.get<Issue>().account = noAccount();
+
+        if (TER const ter = trustCreate(
+                view,              // payment sandbox
+                recvLow,           // is dest low?
+                issuer,            // source
+                receiver,          // destination
+                trustLineKey.key,  // ledger index
+                wrappedDest,       // Account to add to
+                false,             // authorize account
+                !wrappedDest->isFlag(lsfDefaultRipple),
+                false,                      // freeze trust line
+                false,                      // deep freeze trust line
+                initialBalance,             // zero initial balance
+                Issue(currency, receiver),  // limit of zero
+                0,                          // quality in
+                0,                          // quality out
+                journal);                   // journal
+            !isTesSuccess(ter))
+        {
+            return ter;  // LCOV_EXCL_LINE
+        }
+
+        wrappedDest.update();
+    }
+
+    if (!view.exists(trustLineKey) && !receiverIssuer)
+        return tecNO_LINE;
+
+    auto const xferRate = transferRate(view, amount);
+    // update if issuer rate is less than locked rate
+    if (xferRate < lockedRate)
+        lockedRate = xferRate;
+
+    // Transfer Rate only applies when:
+    // 1. Issuer is not involved in the transfer (senderIssuer or
+    // receiverIssuer)
+    // 2. The locked rate is different from the parity rate
+
+    // NOTE: Transfer fee in escrow works a bit differently from a normal
+    // payment. In escrow, the fee is deducted from the locked/sending amount,
+    // whereas in a normal payment, the transfer fee is taken on top of the
+    // sending amount.
+    auto finalAmt = amount;
+    if ((!senderIssuer && !receiverIssuer) && lockedRate != parityRate)
+    {
+        // compute transfer fee, if any
+        auto const xferFee =
+            amount.value() - divideRound(amount, lockedRate, amount.get<Issue>(), true);
+        // compute balance to transfer
+        finalAmt = amount.value() - xferFee;
+    }
+
+    // validate the line limit if the account submitting txn is not the receiver
+    // of the funds
+    if (!createAsset)
+    {
+        auto const sleRippleState = view.peek(trustLineKey);
+        if (!sleRippleState)
+            return tecINTERNAL;  // LCOV_EXCL_LINE
+
+        // if the issuer is the high, then we use the low limit
+        // otherwise we use the high limit
+        STAmount const lineLimit =
+            sleRippleState->getFieldAmount(recvLow ? sfLowLimit : sfHighLimit);
+
+        STAmount lineBalance = sleRippleState->getFieldAmount(sfBalance);
+
+        // flip the sign of the line balance if the issuer is not high
+        if (!recvLow)
+            lineBalance.negate();
+
+        // add the final amount to the line balance
+        lineBalance += finalAmt;
+
+        // if the transfer would exceed the line limit return tecLIMIT_EXCEEDED
+        if (lineLimit < lineBalance)
+            return tecLIMIT_EXCEEDED;
+    }
+
+    // if destination is not the issuer then transfer funds
+    if (!receiverIssuer)
+    {
+        auto const ter = directSendNoFee(view, issuer, receiver, finalAmt, true, journal);
+        if (!isTesSuccess(ter))
+            return ter;  // LCOV_EXCL_LINE
+    }
+    return tesSUCCESS;
+}
+
+template <>
+inline TER
+escrowUnlockApplyHelper<MPTIssue>(
+    ApplyView& view,
+    Rate lockedRate,
+    std::variant<std::shared_ptr<SLE>, WAccountRoot> dest,
+    STAmount const& xrpBalance,
+    STAmount const& amount,
+    AccountID const& issuer,
+    AccountID const& sender,
+    AccountID const& receiver,
+    bool createAsset,
+    beast::Journal journal)
+{
+    bool const senderIssuer = issuer == sender;
+    bool const receiverIssuer = issuer == receiver;
+
+    auto const mptID = amount.get<MPTIssue>().getMptID();
+    auto const issuanceKey = keylet::mptIssuance(mptID);
+    if (!view.exists(keylet::mptoken(issuanceKey.key, receiver)) && createAsset && !receiverIssuer)
+    {
+        // For backwards compatibility: if dest is not WAccountRoot, return error
+        if (!std::holds_alternative<WAccountRoot>(dest))
+            return tefEXCEPTION;
+
+        auto& wrappedDest = std::get<WAccountRoot>(dest);
+
+        if (std::uint32_t const ownerCount = {wrappedDest->at(sfOwnerCount)};
+            xrpBalance < view.fees().accountReserve(ownerCount + 1))
+        {
+            return tecINSUFFICIENT_RESERVE;
+        }
+
+        if (auto const ter = createMPToken(view, mptID, receiver, 0); !isTesSuccess(ter))
+        {
+            return ter;  // LCOV_EXCL_LINE
+        }
+
+        // update owner count.
+        wrappedDest.adjustOwnerCount(1);
+    }
+
+    if (!view.exists(keylet::mptoken(issuanceKey.key, receiver)) && !receiverIssuer)
+        return tecNO_PERMISSION;
+
+    auto const xferRate = transferRate(view, amount);
+    // update if issuer rate is less than locked rate
+    if (xferRate < lockedRate)
+        lockedRate = xferRate;
+
+    // Transfer Rate only applies when:
+    // 1. Issuer is not involved in the transfer (senderIssuer or
+    // receiverIssuer)
+    // 2. The locked rate is different from the parity rate
+
+    // NOTE: Transfer fee in escrow works a bit differently from a normal
+    // payment. In escrow, the fee is deducted from the locked/sending amount,
+    // whereas in a normal payment, the transfer fee is taken on top of the
+    // sending amount.
+    auto finalAmt = amount;
+    if ((!senderIssuer && !receiverIssuer) && lockedRate != parityRate)
+    {
+        // compute transfer fee, if any
+        auto const xferFee = amount.value() - divideRound(amount, lockedRate, amount.asset(), true);
+        // compute balance to transfer
+        finalAmt = amount.value() - xferFee;
+    }
+    return unlockEscrowMPT(
+        view,
+        sender,
+        receiver,
+        finalAmt,
+        view.rules().enabled(fixTokenEscrowV1) ? amount : finalAmt,
+        journal);
+}
+
+}  // namespace xrpl

include/xrpl/ledger/helpers/MPTokenHelpers.h

@@ -14,238 +14,133 @@
 
 namespace xrpl {
 
-class MPTokenIssuance : public virtual TokenBase
-{
-public:
-    MPTokenIssuance(ReadView const& view, MPTIssue const& mptIssue)
-        : ReadOnlySLE(view.read(keylet::mptIssuance(mptIssue.getMptID())), view)
-        , TokenBase(view, view.read(keylet::mptIssuance(mptIssue.getMptID())))
-        , mptID_(mptIssue.getMptID())
-        , mptIssue_(mptIssue)
-    {
-    }
+//------------------------------------------------------------------------------
+//
+// Freeze checking (MPT-specific)
+//
+//------------------------------------------------------------------------------
 
-    MPTokenIssuance(ReadView const& view, MPTID const& mptID)
-        : ReadOnlySLE(view.read(keylet::mptIssuance(mptID)), view)
-        , TokenBase(view, view.read(keylet::mptIssuance(mptID)))
-        , mptID_(mptID)
-        , mptIssue_(MPTIssue(mptID_))
-    {
-    }
+[[nodiscard]] bool
+isGlobalFrozen(ReadView const& view, MPTIssue const& mptIssue);
 
-    MPTID const&
-    getMptID() const
-    {
-        return mptID_;
-    }
+[[nodiscard]] bool
+isIndividualFrozen(ReadView const& view, AccountID const& account, MPTIssue const& mptIssue);
 
-    MPTIssue const&
-    getMptIssue() const
-    {
-        return mptIssue_;
-    }
+[[nodiscard]] bool
+isFrozen(ReadView const& view, AccountID const& account, MPTIssue const& mptIssue, int depth = 0);
 
-    AccountID const&
-    getIssuer() const
-    {
-        return mptIssue_.getIssuer();
-    }
+[[nodiscard]] bool
+isAnyFrozen(
+    ReadView const& view,
+    std::initializer_list<AccountID> const& accounts,
+    MPTIssue const& mptIssue,
+    int depth = 0);
 
-    //------------------------------------------------------------------------------
-    //
-    // Freeze checking (MPT-specific)
-    //
-    //------------------------------------------------------------------------------
+//------------------------------------------------------------------------------
+//
+// Transfer rate (MPT-specific)
+//
+//------------------------------------------------------------------------------
 
-    [[nodiscard]] bool
-    isGlobalFrozen() const override;
+/** Returns MPT transfer fee as Rate. Rate specifies
+ * the fee as fractions of 1 billion. For example, 1% transfer rate
+ * is represented as 1,010,000,000.
+ * @param issuanceID MPTokenIssuanceID of MPTTokenIssuance object
+ */
+[[nodiscard]] Rate
+transferRate(ReadView const& view, MPTID const& issuanceID);
 
-    [[nodiscard]] bool
-    isIndividualFrozen(AccountID const& account) const override;
+//------------------------------------------------------------------------------
+//
+// Holding checks (MPT-specific)
+//
+//------------------------------------------------------------------------------
 
-    [[nodiscard]] bool
-    isFrozen(AccountID const& account, int depth = 0) const override;
+[[nodiscard]] TER
+canAddHolding(ReadView const& view, MPTIssue const& mptIssue);
 
-    [[nodiscard]] TER
-    checkFrozen(AccountID const& account) const override;
+//------------------------------------------------------------------------------
+//
+// Authorization (MPT-specific)
+//
+//------------------------------------------------------------------------------
 
-    [[nodiscard]] bool
-    isAnyFrozen(std::initializer_list<AccountID> const& accounts, int depth = 0) const override;
+[[nodiscard]] TER
+authorizeMPToken(
+    ApplyView& view,
+    XRPAmount const& priorBalance,
+    MPTID const& mptIssuanceID,
+    AccountID const& account,
+    beast::Journal journal,
+    std::uint32_t flags = 0,
+    std::optional<AccountID> holderID = std::nullopt);
 
-    [[nodiscard]] bool
-    isDeepFrozen(AccountID const& account, int depth = 0) const override;
+/** Check if the account lacks required authorization for MPT.
+ *
+ * requireAuth check is recursive for MPT shares in a vault, descending to
+ * assets in the vault, up to maxAssetCheckDepth recursion depth. This is
+ * purely defensive, as we currently do not allow such vaults to be created.
+ * WeakAuth intentionally allows missing MPTokens under MPToken V2.
+ */
+[[nodiscard]] TER
+requireAuth(
+    ReadView const& view,
+    MPTIssue const& mptIssue,
+    AccountID const& account,
+    AuthType authType = AuthType::Legacy,
+    int depth = 0);
 
-    [[nodiscard]] TER
-    checkDeepFrozen(AccountID const& account) const override;
+/** Enforce account has MPToken to match its authorization.
+ *
+ *   Called from doApply - it will check for expired (and delete if found any)
+ *   credentials matching DomainID set in MPTokenIssuance. Must be called if
+ *   requireAuth(...MPTIssue...) returned tesSUCCESS or tecEXPIRED in preclaim.
+ */
+[[nodiscard]] TER
+enforceMPTokenAuthorization(
+    ApplyView& view,
+    MPTID const& mptIssuanceID,
+    AccountID const& account,
+    XRPAmount const& priorBalance,
+    beast::Journal j);
 
-    //------------------------------------------------------------------------------
-    //
-    // Transfer rate (MPT-specific)
-    //
-    //------------------------------------------------------------------------------
+/** Check if the destination account is allowed
+ *  to receive MPT. Return tecNO_AUTH if it doesn't
+ *  and tesSUCCESS otherwise.
+ */
+[[nodiscard]] TER
+canTransfer(
+    ReadView const& view,
+    MPTIssue const& mptIssue,
+    AccountID const& from,
+    AccountID const& to);
 
-    /** Returns MPT transfer fee as Rate. Rate specifies
-     * the fee as fractions of 1 billion. For example, 1% transfer rate
-     * is represented as 1,010,000,000.
-     * @param issuanceID MPTokenIssuanceID of MPTTokenIssuance object
-     */
-    [[nodiscard]] Rate
-    transferRate() const override;
+/** Check if Asset can be traded on DEX. return tecNO_PERMISSION
+ * if it doesn't and tesSUCCESS otherwise.
+ */
+[[nodiscard]] TER
+canTrade(ReadView const& view, Asset const& asset);
 
-    //------------------------------------------------------------------------------
-    //
-    // Holding checks (MPT-specific)
-    //
-    //------------------------------------------------------------------------------
+//------------------------------------------------------------------------------
+//
+// Empty holding operations (MPT-specific)
+//
+//------------------------------------------------------------------------------
 
-    [[nodiscard]] TER
-    canAddHolding() const override;
+[[nodiscard]] TER
+addEmptyHolding(
+    ApplyView& view,
+    AccountID const& accountID,
+    XRPAmount priorBalance,
+    MPTIssue const& mptIssue,
+    beast::Journal journal);
 
-    /** Check if the account lacks required authorization for MPT.
-     *
-     * requireAuth check is recursive for MPT shares in a vault, descending to
-     * assets in the vault, up to maxAssetCheckDepth recursion depth. This is
-     * purely defensive, as we currently do not allow such vaults to be created.
-     */
-    [[nodiscard]] TER
-    requireAuth(AccountID const& account, AuthType authType = AuthType::Legacy, int depth = 0)
-        const override;
-
-    /** Check if the destination account is allowed
-     *  to receive MPT. Return tecNO_AUTH if it doesn't
-     *  and tesSUCCESS otherwise.
-     */
-    [[nodiscard]] TER
-    canTransfer(AccountID const& from, AccountID const& to) const override;
-
-    //------------------------------------------------------------------------------
-    //
-    // Token capability checks (MPT-specific)
-    //
-    //------------------------------------------------------------------------------
-
-    [[nodiscard]] bool
-    canClawback() const override;
-
-    [[nodiscard]] bool
-    requiresAuth() const override;
-
-    STAmount
-    accountHolds(
-        AccountID const& account,
-        FreezeHandling zeroIfFrozen,
-        beast::Journal j,
-        SpendableHandling includeFullBalance = shSIMPLE_BALANCE) const override;
-
-    [[nodiscard]] STAmount
-    accountHolds(
-        AccountID const& account,
-        FreezeHandling zeroIfFrozen,
-        AuthHandling zeroIfUnauthorized,
-        beast::Journal j,
-        SpendableHandling includeFullBalance = shSIMPLE_BALANCE) const override;
-
-protected:
-    MPTID const mptID_;
-    MPTIssue const mptIssue_;
-};
-
-class WritableMPTokenIssuance : public virtual WritableTokenBase, public virtual MPTokenIssuance
-{
-public:
-    WritableMPTokenIssuance(ApplyView& view, MPTIssue const& mptIssue)
-        : ReadOnlySLE(view.peek(keylet::mptIssuance(mptIssue.getMptID())), view)
-        , TokenBase(view, view.peek(keylet::mptIssuance(mptIssue.getMptID())))
-        , WritableSLE(view.peek(keylet::mptIssuance(mptIssue.getMptID())), view)
-        , WritableTokenBase(view, view.peek(keylet::mptIssuance(mptIssue.getMptID())))
-        , MPTokenIssuance(view, mptIssue)
-    {
-    }
-
-    WritableMPTokenIssuance(ApplyView& view, MPTID const& mptID)
-        : ReadOnlySLE(view.peek(keylet::mptIssuance(mptID)), view)
-        , TokenBase(view, view.peek(keylet::mptIssuance(mptID)))
-        , WritableSLE(view.peek(keylet::mptIssuance(mptID)), view)
-        , WritableTokenBase(view, view.peek(keylet::mptIssuance(mptID)))
-        , MPTokenIssuance(view, mptID)
-    {
-    }
-
-    // Resolve ambiguity: use writable operator-> for non-const, read-only for const
-    using WritableSLE::operator->;
-    using MPTokenIssuance::operator->;
-    using WritableSLE::operator*;
-    using MPTokenIssuance::operator*;
-
-    //------------------------------------------------------------------------------
-    //
-    // Authorization (MPT-specific)
-    //
-    //------------------------------------------------------------------------------
-
-    [[nodiscard]] TER
-    authorizeMPToken(
-        XRPAmount const& priorBalance,
-        AccountID const& account,
-        beast::Journal journal,
-        std::uint32_t flags = 0,
-        std::optional<AccountID> holderID = std::nullopt);
-
-    /** Enforce account has MPToken to match its authorization.
-     *
-     *   Called from doApply - it will check for expired (and delete if found any)
-     *   credentials matching DomainID set in MPTokenIssuance. Must be called if
-     *   requireAuth(...MPTIssue...) returned tesSUCCESS or tecEXPIRED in preclaim.
-     */
-    [[nodiscard]] TER
-    enforceMPTokenAuthorization(
-        AccountID const& account,
-        XRPAmount const& priorBalance,
-        beast::Journal j);
-
-    //------------------------------------------------------------------------------
-    //
-    // Empty holding operations (MPT-specific)
-    //
-    //------------------------------------------------------------------------------
-
-    [[nodiscard]] TER
-    addEmptyHolding(AccountID const& accountID, XRPAmount priorBalance, beast::Journal journal)
-        override;
-
-    [[nodiscard]] TER
-    removeEmptyHolding(AccountID const& accountID, beast::Journal journal) override;
-
-    /** Create a WritableMPTokenIssuance backed by a brand-new SLE
-     *  (not yet inserted into the view).
-     */
-    [[nodiscard]] static WritableMPTokenIssuance
-    makeNew(MPTID const& mptID, ApplyView& view)
-    {
-        return WritableMPTokenIssuance(
-            mptID, std::make_shared<SLE>(keylet::mptIssuance(mptID)), view);
-    }
-
-    [[nodiscard]] static WritableMPTokenIssuance
-    makeNew(std::uint32_t const seq, AccountID const& issuer, ApplyView& view)
-    {
-        auto const mptID = makeMptID(seq, issuer);
-        return WritableMPTokenIssuance(
-            mptID, std::make_shared<SLE>(keylet::mptIssuance(mptID)), view);
-    }
-
-private:
-    // This is a private constructor only used by `makeNew`
-    WritableMPTokenIssuance(MPTID const& mptID, std::shared_ptr<SLE> sle, ApplyView& view)
-        : ReadOnlySLE(sle, view)
-        , TokenBase(view, sle)
-        , WritableSLE(sle, view)
-        , WritableTokenBase(view, sle)
-        , MPTokenIssuance(view, mptID)
-    {
-        insert();
-    }
-};
+[[nodiscard]] TER
+removeEmptyHolding(
+    ApplyView& view,
+    AccountID const& accountID,
+    MPTIssue const& mptIssue,
+    beast::Journal journal);
 
 //------------------------------------------------------------------------------
 //
@@ -254,14 +149,14 @@ private:
 //------------------------------------------------------------------------------
 
 TER
-rippleLockEscrowMPT(
+lockEscrowMPT(
     ApplyView& view,
     AccountID const& uGrantorID,
     STAmount const& saAmount,
     beast::Journal j);
 
 TER
-rippleUnlockEscrowMPT(
+unlockEscrowMPT(
     ApplyView& view,
     AccountID const& uGrantorID,
     AccountID const& uGranteeID,
@@ -269,4 +164,80 @@ rippleUnlockEscrowMPT(
     STAmount const& grossAmount,
     beast::Journal j);
 
+TER
+createMPToken(
+    ApplyView& view,
+    MPTID const& mptIssuanceID,
+    AccountID const& account,
+    std::uint32_t const flags);
+
+TER
+checkCreateMPT(
+    xrpl::ApplyView& view,
+    xrpl::MPTIssue const& mptIssue,
+    xrpl::AccountID const& holder,
+    beast::Journal j);
+
+//------------------------------------------------------------------------------
+//
+// MPT Overflow related
+//
+//------------------------------------------------------------------------------
+
+// MaximumAmount doesn't exceed 2**63-1
+std::int64_t
+maxMPTAmount(SLE const& sleIssuance);
+
+// OutstandingAmount may overflow and available amount might be negative.
+// But available amount is always <= |MaximumAmount - OutstandingAmount|.
+std::int64_t
+availableMPTAmount(SLE const& sleIssuance);
+
+std::int64_t
+availableMPTAmount(ReadView const& view, MPTID const& mptID);
+
+/** Checks for two types of OutstandingAmount overflow during a send operation.
+ * 1.  **Direct directSendNoFee (Overflow: No):** A true overflow check when
+ * `OutstandingAmount > MaximumAmount`. This threshold is used for direct
+ * directSendNoFee transactions that bypass the payment engine.
+ * 2.  **accountSend & Payment Engine (Overflow: Yes):** A temporary overflow
+ * check when `OutstandingAmount > UINT64_MAX`. This higher threshold is used
+ * for `accountSend` and payments processed via the payment engine.
+ */
+bool
+isMPTOverflow(
+    std::int64_t sendAmount,
+    std::uint64_t outstandingAmount,
+    std::int64_t maximumAmount,
+    AllowMPTOverflow allowOverflow);
+
+/**
+ * Determine funds available for an issuer to sell in an issuer owned offer.
+ * Issuing step, which could be either MPTEndPointStep last step or BookStep's
+ * TakerPays may overflow OutstandingAmount. Redeeming step, in BookStep's
+ * TakerGets redeems the offer's owner funds, essentially balancing out
+ * the overflow, unless the offer's owner is the issuer.
+ */
+[[nodiscard]] STAmount
+issuerFundsToSelfIssue(ReadView const& view, MPTIssue const& issue);
+
+/** Facilitate tracking of MPT sold by an issuer owning MPT sell offer.
+ * See ApplyView::issuerSelfDebitHookMPT().
+ */
+void
+issuerSelfDebitHookMPT(ApplyView& view, MPTIssue const& issue, std::uint64_t amount);
+
+//------------------------------------------------------------------------------
+//
+// MPT DEX
+//
+//------------------------------------------------------------------------------
+
+/* Return true if a transaction is allowed for the specified MPT/account. The
+ * function checks MPTokenIssuance and MPToken objects flags to determine if the
+ * transaction is allowed.
+ */
+TER
+checkMPTTxAllowed(ReadView const& v, TxType tx, Asset const& asset, AccountID const& accountID);
+
 }  // namespace xrpl

include/xrpl/ledger/helpers/NFTokenHelpers.h

@@ -1,12 +1,12 @@
 #pragma once
 
+#include <xrpl/basics/Log.h>
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/ledger/ApplyView.h>
 #include <xrpl/protocol/AccountID.h>
 #include <xrpl/protocol/TER.h>
 #include <xrpl/protocol/TxFlags.h>
 #include <xrpl/protocol/nft.h>
-#include <xrpl/tx/Transactor.h>
 
 namespace xrpl {
 

include/xrpl/ledger/helpers/PaymentChannelHelpers.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include <xrpl/ledger/ApplyView.h>
+#include <xrpl/protocol/UintTypes.h>
+
+namespace xrpl {
+
+TER
+closeChannel(
+    std::shared_ptr<SLE> const& slep,
+    ApplyView& view,
+    uint256 const& key,
+    beast::Journal j);
+
+}  // namespace xrpl

include/xrpl/ledger/helpers/README.md

@@ -1,8 +1,8 @@
-# Ledger Entry Helpers (`entries/`)
+# Ledger Entry Helpers (`helpers/`)
 
 ## Overview
 
-This folder contains helper classes and free functions for working with **Serialized Ledger Entries (SLEs)**. Its centerpiece is `SLEBase.h`, which defines two base classes — `ReadOnlySLE` and `WritableSLE` — that provide a type-safe, context-aware wrapper around the raw `std::shared_ptr<SLE>` used throughout the rest of the codebase.
+This folder contains helper classes and free functions for working with **Serialized Ledger Entries (SLEs)**. Its centerpiece is `SLEBase.h`, which defines the template class `SLEBase<ViewT>` — a type-safe, context-aware wrapper around the raw `std::shared_ptr<SLE>` used throughout the rest of the codebase.
 
 ## The Problem: Untyped SLE Access
 
@@ -16,24 +16,39 @@ Historically, ledger entries are passed around as bare `std::shared_ptr<SLE>` (o
 
 ## The Solution: `SLEBase.h`
 
-`SLEBase.h` introduces two base classes that pair an SLE with its view context and enforce read/write semantics at compile time.
+`SLEBase.h` introduces a single template class `SLEBase<ViewT>` that pairs an SLE with its view context and enforces read/write semantics at compile time via `requires` clauses.
 
-**`ReadOnlySLE`** bundles a `std::shared_ptr<SLE const>` with the `ReadView` it was read from. It provides existence checks and const-only access to the underlying entry. Derived classes add domain-specific read-only accessors (e.g. `AccountRoot::isGlobalFrozen()`).
+**`SLEBase<ReadView>`** (aliased as `ReadOnlySLE`) holds a `std::shared_ptr<SLE const>` and a `ReadView const&`. Write-only members are excluded at compile time.
 
-**`WritableSLE`** bundles a mutable `std::shared_ptr<SLE>` with the `ApplyView` used for writes. It provides helpers to insert, update, and erase the entry in the view, keeping the SLE and its view in sync automatically.
+**`SLEBase<ApplyView>`** (aliased as `WritableSLE`) holds a mutable `std::shared_ptr<SLE>`, an `ApplyView&`, and a `Keylet`. It exposes `insert()`, `update()`, `erase()`, and `newSLE()` to keep the SLE and its view in sync automatically.
 
-### Dual-Inheritance Pattern
+A converting constructor allows implicit conversion from `SLEBase<ApplyView>` to `SLEBase<ReadView>`, so functions taking a read-only wrapper can accept a writable one without a cast.
 
-Concrete writable wrappers inherit from _both_ the read-only wrapper and `WritableSLE`:
+### Template Pattern
+
+Each entry type is a single template class parameterized on the view type:
 
 ```
-WritableAccountRoot
-  ├── AccountRoot   (extends ReadOnlySLE)  — read-only domain methods
-  └── WritableSLE                          — write capabilities
+AccountRoot<ReadView>   — read-only:  RAccountRoot
+AccountRoot<ApplyView>  — writable:   WAccountRoot
 ```
 
-This lets a writable wrapper reuse all read-only domain logic from its parent while gaining mutation and persistence operations from `WritableSLE`.
+Both specializations share all domain read methods. Write methods on `WAccountRoot` are gated with `requires is_writable` so they are unavailable on `RAccountRoot` at compile time. The `R`/`W` prefix aliases (`RAccountRoot`, `WAccountRoot`) are provided for convenience and backward compatibility.
+
+## Files in This Directory
+
+| File                   | Description                                                                                                                                                 |
+| ---------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| `SLEBase.h`            | Template base class `SLEBase<ViewT>` and `ReadOnlySLE`/`WritableSLE` aliases                                                                                |
+| `AccountRootHelpers.h` | `AccountRoot<ViewT>` wrapper (`RAccountRoot`, `WAccountRoot`) and free functions for pseudo-accounts                                                        |
+| `CredentialHelpers.h`  | Free functions for Credential ledger entries                                                                                                                |
+| `DirectoryHelpers.h`   | Free functions for directory traversal (`dirFirst`, `dirNext`, `forEachItem`, etc.)                                                                         |
+| `MPTokenHelpers.h`     | Free functions for MPToken ledger entries and MPTokenIssuance<ViewT> wrapper (`RMPTokenIssuance`, `WMPTokenIssuance`) functions for MPTokenIssuance objects |
+| `OfferHelpers.h`       | Free function `offerDelete` for removing Offer entries                                                                                                      |
+| `RippleStateHelpers.h` | Free functions for RippleState (trust line) entries: credit, freeze, issuance, authorization                                                                |
+| `TokenHelpers.h`       | Shared token helpers (freeze/auth checks used by both IOU and MPT paths)                                                                                    |
+| `VaultHelpers.h`       | Free functions for Vault ledger entries                                                                                                                     |
 
 ## Migration Status
 
-This migration is still in progress and is still in the early stages. New code should prefer the wrapper style where possible; existing free functions will be migrated incrementally.
+This migration is still in progress. New code should prefer the wrapper style where possible; existing free functions will be migrated incrementally.

include/xrpl/ledger/helpers/RippleStateHelpers.h

@@ -19,191 +19,6 @@
 
 namespace xrpl {
 
-class IOUToken : public virtual TokenBase
-{
-public:
-    IOUToken(ReadView const& view, Issue const& issue)
-        : ReadOnlySLE(view.read(keylet::account(issue.getIssuer())), view)
-        , TokenBase(view, view.read(keylet::account(issue.getIssuer())))
-        , issue_(issue)
-        , issuer_(issue.getIssuer())
-        , issuerAccount_(issuer_, view)
-        , currency_(issue.currency)
-    {
-    }
-
-    IOUToken(ReadView const& view, AccountID const& issuer, Currency const& currency)
-        : IOUToken(view, Issue{currency, issuer})
-    {
-    }
-
-    [[nodiscard]] AccountID const&
-    getIssuer() const
-    {
-        return issuer_;
-    }
-
-    [[nodiscard]] Currency const&
-    getCurrency() const
-    {
-        return currency_;
-    }
-
-    [[nodiscard]] bool
-    isGlobalFrozen() const override
-    {
-        return issuerAccount_.isGlobalFrozen();
-    }
-
-    [[nodiscard]] bool
-    isIndividualFrozen(AccountID const& account) const override;
-
-    [[nodiscard]] bool
-    isFrozen(AccountID const& account, int depth = 0) const override;
-
-    [[nodiscard]] TER
-    checkFrozen(AccountID const& account) const override;
-
-    [[nodiscard]] bool
-    isAnyFrozen(std::initializer_list<AccountID> const& accounts, int depth = 0) const override;
-
-    [[nodiscard]] bool
-    isDeepFrozen(AccountID const& account, int depth = 0) const override;
-
-    [[nodiscard]] TER
-    checkDeepFrozen(AccountID const& account) const override;
-
-    [[nodiscard]] Rate
-    transferRate() const override;
-
-    STAmount
-    accountHolds(
-        AccountID const& account,
-        FreezeHandling zeroIfFrozen,
-        beast::Journal j,
-        SpendableHandling includeFullBalance = shSIMPLE_BALANCE) const override;
-
-    [[nodiscard]] STAmount
-    accountHolds(
-        AccountID const& account,
-        FreezeHandling zeroIfFrozen,
-        AuthHandling zeroIfUnauthorized,
-        beast::Journal j,
-        SpendableHandling includeFullBalance = shSIMPLE_BALANCE) const override;
-
-    /** Returns the funds available for account to pay for an amount.
-     *
-     * If the account is the issuer of the currency, it can always
-     * afford to pay (returns saDefault as-is). Otherwise, returns
-     * the result of accountHolds.
-     */
-    [[nodiscard]] STAmount
-    accountFunds(
-        AccountID const& id,
-        STAmount const& saDefault,
-        FreezeHandling freezeHandling,
-        beast::Journal j) const;
-
-    [[nodiscard]] TER
-    canAddHolding() const override;
-
-    //------------------------------------------------------------------------------
-    //
-    // Authorization and transfer checks (Asset-based dispatchers)
-    //
-    //------------------------------------------------------------------------------
-
-    [[nodiscard]] TER
-    requireAuth(AccountID const& account, AuthType authType = AuthType::Legacy, int depth = 0)
-        const override;
-
-    [[nodiscard]] TER
-    canTransfer(AccountID const& from, AccountID const& to) const override;
-
-    //------------------------------------------------------------------------------
-    //
-    // Token capability checks (IOU-specific)
-    //
-    //------------------------------------------------------------------------------
-
-    [[nodiscard]] bool
-    canClawback() const override;
-
-    [[nodiscard]] bool
-    requiresAuth() const override;
-
-protected:
-    Issue const issue_;
-    AccountID const issuer_;
-    AccountRoot const issuerAccount_;
-    Currency const currency_;
-};
-
-class WritableIOUToken : public virtual WritableTokenBase, public virtual IOUToken
-{
-public:
-    WritableIOUToken(ApplyView& view, Issue const& issue)
-        : ReadOnlySLE(view.peek(keylet::account(issue.getIssuer())), view)
-        , TokenBase(view, view.peek(keylet::account(issue.getIssuer())))
-        , WritableSLE(view.peek(keylet::account(issue.getIssuer())), view)
-        , WritableTokenBase(view, view.peek(keylet::account(issue.getIssuer())))
-        , IOUToken(view, issue)
-    {
-    }
-
-    WritableIOUToken(ApplyView& view, AccountID const& issuer, Currency const& currency)
-        : WritableIOUToken(view, Issue{currency, issuer})
-    {
-    }
-
-    // Resolve ambiguity: use writable operator-> for non-const, read-only for const
-    using WritableSLE::operator->;
-    using IOUToken::operator->;
-    using WritableSLE::operator*;
-    using IOUToken::operator*;
-
-    //------------------------------------------------------------------------------
-    //
-    // Holding management (WritableTokenBase interface)
-    //
-    //------------------------------------------------------------------------------
-
-    [[nodiscard]] TER
-    addEmptyHolding(AccountID const& accountID, XRPAmount priorBalance, beast::Journal journal)
-        override;
-
-    [[nodiscard]] TER
-    removeEmptyHolding(AccountID const& accountID, beast::Journal journal) override;
-
-    /** Create a WritableIOUToken backed by a brand-new SLE
-     *  (not yet inserted into the view).
-     */
-    [[nodiscard]] static WritableIOUToken
-    makeNew(AccountID const& id, Currency const& currency, ApplyView& view)
-    {
-        return makeNew(Issue{currency, id}, view);
-    }
-
-    [[nodiscard]] static WritableIOUToken
-    makeNew(Issue const& issue, ApplyView& view)
-    {
-        return WritableIOUToken(
-            issue, view, std::make_shared<SLE>(keylet::account(issue.getIssuer())));
-    }
-
-private:
-    // This is a private constructor only used by `makeNew`
-    WritableIOUToken(Issue const& issue, ApplyView& view, std::shared_ptr<SLE> sle)
-        : ReadOnlySLE(sle, view)
-        , TokenBase(view, sle)
-        , WritableSLE(sle, view)
-        , WritableTokenBase(view, sle)
-        , IOUToken(view, issue)
-    {
-        insert();
-    }
-};
-
 //------------------------------------------------------------------------------
 //
 // Credit functions (from Credit.h)
@@ -244,6 +59,69 @@ creditBalance(
     Currency const& currency);
 /** @} */
 
+//------------------------------------------------------------------------------
+//
+// Freeze checking (IOU-specific)
+//
+//------------------------------------------------------------------------------
+
+[[nodiscard]] bool
+isIndividualFrozen(
+    ReadView const& view,
+    AccountID const& account,
+    Currency const& currency,
+    AccountID const& issuer);
+
+[[nodiscard]] inline bool
+isIndividualFrozen(ReadView const& view, AccountID const& account, Issue const& issue)
+{
+    return isIndividualFrozen(view, account, issue.currency, issue.account);
+}
+
+[[nodiscard]] bool
+isFrozen(
+    ReadView const& view,
+    AccountID const& account,
+    Currency const& currency,
+    AccountID const& issuer);
+
+[[nodiscard]] inline bool
+isFrozen(ReadView const& view, AccountID const& account, Issue const& issue)
+{
+    return isFrozen(view, account, issue.currency, issue.account);
+}
+
+// Overload with depth parameter for uniformity with MPTIssue version.
+// The depth parameter is ignored for IOUs since they don't have vault recursion.
+[[nodiscard]] inline bool
+isFrozen(ReadView const& view, AccountID const& account, Issue const& issue, int /*depth*/)
+{
+    return isFrozen(view, account, issue);
+}
+
+[[nodiscard]] bool
+isDeepFrozen(
+    ReadView const& view,
+    AccountID const& account,
+    Currency const& currency,
+    AccountID const& issuer);
+
+[[nodiscard]] inline bool
+isDeepFrozen(
+    ReadView const& view,
+    AccountID const& account,
+    Issue const& issue,
+    int = 0 /*ignored*/)
+{
+    return isDeepFrozen(view, account, issue.currency, issue.account);
+}
+
+[[nodiscard]] inline TER
+checkDeepFrozen(ReadView const& view, AccountID const& account, Issue const& issue)
+{
+    return isDeepFrozen(view, account, issue) ? (TER)tecFROZEN : (TER)tesSUCCESS;
+}
+
 //------------------------------------------------------------------------------
 //
 // Trust line operations
@@ -260,16 +138,16 @@ trustCreate(
     bool const bSrcHigh,
     AccountID const& uSrcAccountID,
     AccountID const& uDstAccountID,
-    uint256 const& uIndex,             // ripple state entry
-    WritableAccountRoot& wrappedAcct,  // the account being set.
-    bool const bAuth,                  // authorize account.
-    bool const bNoRipple,              // others cannot ripple through
-    bool const bFreeze,                // funds cannot leave
-    bool bDeepFreeze,                  // can neither receive nor send funds
-    STAmount const& saBalance,         // balance of account being set.
-                                       // Issuer should be noAccount()
-    STAmount const& saLimit,           // limit for account being set.
-                                       // Issuer should be the account being set.
+    uint256 const& uIndex,      // ripple state entry
+    WAccountRoot& wrappedAcct,  // the account being set.
+    bool const bAuth,           // authorize account.
+    bool const bNoRipple,       // others cannot ripple through
+    bool const bFreeze,         // funds cannot leave
+    bool bDeepFreeze,           // can neither receive nor send funds
+    STAmount const& saBalance,  // balance of account being set.
+                                // Issuer should be noAccount()
+    STAmount const& saLimit,    // limit for account being set.
+                                // Issuer should be the account being set.
     std::uint32_t uQualityIn,
     std::uint32_t uQualityOut,
     beast::Journal j);
@@ -304,6 +182,43 @@ redeemIOU(
     Issue const& issue,
     beast::Journal j);
 
+//------------------------------------------------------------------------------
+//
+// Authorization and transfer checks (IOU-specific)
+//
+//------------------------------------------------------------------------------
+
+/** Check if the account lacks required authorization.
+ *
+ * Return tecNO_AUTH or tecNO_LINE if it does
+ * and tesSUCCESS otherwise.
+ *
+ * If StrongAuth then return tecNO_LINE if the RippleState doesn't exist. Return
+ * tecNO_AUTH if lsfRequireAuth is set on the issuer's AccountRoot, and the
+ * RippleState does exist, and the RippleState is not authorized.
+ *
+ * If WeakAuth then return tecNO_AUTH if lsfRequireAuth is set, and the
+ * RippleState exists, and is not authorized. Return tecNO_LINE if
+ * lsfRequireAuth is set and the RippleState doesn't exist. Consequently, if
+ * WeakAuth and lsfRequireAuth is *not* set, this function will return
+ * tesSUCCESS even if RippleState does *not* exist.
+ *
+ * The default "Legacy" auth type is equivalent to WeakAuth.
+ */
+[[nodiscard]] TER
+requireAuth(
+    ReadView const& view,
+    Issue const& issue,
+    AccountID const& account,
+    AuthType authType = AuthType::Legacy);
+
+/** Check if the destination account is allowed
+ *  to receive IOU. Return terNO_RIPPLE if rippling is
+ *  disabled on both sides and tesSUCCESS otherwise.
+ */
+[[nodiscard]] TER
+canTransfer(ReadView const& view, Issue const& issue, AccountID const& from, AccountID const& to);
+
 //------------------------------------------------------------------------------
 //
 // Empty holding operations (IOU-specific)
@@ -338,4 +253,14 @@ deleteAMMTrustLine(
     std::optional<AccountID> const& ammAccountID,
     beast::Journal j);
 
+/** Delete AMMs MPToken. The passed `sle` must be obtained from a prior
+ * call to view.peek().
+ */
+[[nodiscard]] TER
+deleteAMMMPToken(
+    ApplyView& view,
+    std::shared_ptr<SLE> sleMPT,
+    AccountID const& ammAccountID,
+    beast::Journal j);
+
 }  // namespace xrpl

include/xrpl/ledger/helpers/SLEBase.h

@@ -4,33 +4,52 @@
 #include <xrpl/ledger/ReadView.h>
 #include <xrpl/protocol/STLedgerEntry.h>
 
+#include <concepts>
 #include <memory>
 #include <stdexcept>
+#include <type_traits>
 
 namespace xrpl {
 
+// Concept to distinguish read-only vs writable view types
+template <typename V>
+concept WritableView = std::derived_from<V, ApplyView>;
+
 /**
- * Read-only base class for all ledger entry view classes.
+ * View-parameterized base class for all ledger entry wrappers.
  *
- * Provides common functionality for existence checking and raw SLE read access.
- * Supports read-only (ReadView) contexts.
+ * SLEBase<ReadView>  — read-only:  holds shared_ptr<SLE const> + ReadView const&
+ * SLEBase<ApplyView> — writable:   holds shared_ptr<SLE> + ApplyView& + Keylet,
+ *                                   plus insert/update/erase operations
+ *
+ * Write-only members are gated by `requires` clauses, providing compile-time
+ * guarantees that read-only wrappers cannot mutate state.
  *
  * Derived classes should provide domain-specific accessors that hide
  * implementation details of the underlying ledger entry format.
  */
-class ReadOnlySLE
+template <typename ViewT>
+class SLEBase
 {
 public:
-    virtual ~ReadOnlySLE() = default;
+    static constexpr bool is_writable = WritableView<ViewT>;
 
-    // Copy/move constructors are fine (reference can be initialized from another)
-    ReadOnlySLE(ReadOnlySLE const&) = default;
-    ReadOnlySLE(ReadOnlySLE&&) = default;
-    // Assignment operators are deleted (cannot rebind reference members)
-    ReadOnlySLE&
-    operator=(ReadOnlySLE const&) = delete;
-    ReadOnlySLE&
-    operator=(ReadOnlySLE&&) = delete;
+    // SLE pointer type: mutable for writable views, const for read-only
+    using sle_ptr_type = std::conditional_t<is_writable, std::shared_ptr<SLE>, SLE::const_pointer>;
+
+    // View reference type: ApplyView& for writable, ReadView const& for read-only
+    using view_ref_type = std::conditional_t<is_writable, ApplyView&, ReadView const&>;
+
+    virtual ~SLEBase() = default;
+
+    SLEBase(SLEBase const&) = default;
+    SLEBase(SLEBase&&) = default;
+    SLEBase&
+    operator=(SLEBase const&) = delete;
+    SLEBase&
+    operator=(SLEBase&&) = delete;
+
+    // --- Common interface (always available) ---
 
     /** Returns true if the ledger entry exists */
     bool
@@ -46,155 +65,176 @@ public:
         return exists();
     }
 
-    /** Returns the underlying SLE for read access (always available) */
-    std::shared_ptr<SLE const> const&
+    /** Returns the underlying SLE for read access */
+    SLE::const_pointer
     sle() const
     {
         return sle_;
     }
 
-    /** Returns the read view (always available) */
+    /** Returns the read view (always available; ApplyView inherits ReadView) */
     ReadView const&
     readView() const
     {
-        return readView_;
+        return view_;
     }
 
+    /** Const dereference operators (always available) */
     STLedgerEntry const*
     operator->() const
     {
-        XRPL_ASSERT(exists(), "xrpl::ReadOnlySLE::operator-> : exists");
+        XRPL_ASSERT(exists(), "xrpl::SLEBase::operator-> : exists");
         return sle_.get();
     }
 
     STLedgerEntry const&
     operator*() const
     {
-        XRPL_ASSERT(exists(), "xrpl::ReadOnlySLE::operator* : exists");
+        XRPL_ASSERT(exists(), "xrpl::SLEBase::operator* : exists");
         return *sle_;
     }
 
-protected:
-    // Default constructor is deleted (cannot leave reference uninitialized)
-    ReadOnlySLE() = delete;
-
-    /** Constructor for read-only context (ReadView) */
-    explicit ReadOnlySLE(std::shared_ptr<SLE const> sle, ReadView const& view)
-        : sle_(std::move(sle)), readView_(view)
-    {
-    }
-
-    std::shared_ptr<SLE const> sle_;  // Always valid (const view)
-    ReadView const& readView_;        // Always valid
-};
-
-/**
- * Writable base class for all ledger entry view classes.
- *
- * Extends ReadOnlySLE with write access capabilities.
- * Supports read-write (ApplyView) contexts.
- *
- * Derived classes should provide domain-specific accessors that hide
- * implementation details of the underlying ledger entry format.
- */
-class WritableSLE
-{
-public:
-    virtual ~WritableSLE() = default;
-
-    // Copy/move constructors are fine (reference can be initialized from another)
-    WritableSLE(WritableSLE const&) = default;
-    WritableSLE(WritableSLE&&) = default;
-    // Assignment operators are deleted (cannot rebind reference members)
-    WritableSLE&
-    operator=(WritableSLE const&) = delete;
-    WritableSLE&
-    operator=(WritableSLE&&) = delete;
+    // --- Writable interface (compile-time gated) ---
 
     /** Returns a mutable SLE for write operations */
-    std::shared_ptr<SLE> const&
+    sle_ptr_type const&
     mutableSle() const
+        requires is_writable
     {
-        return mutableSle_;
+        return sle_;
     }
 
     /** Returns true if this wrapper supports write operations */
     bool
     canModify() const
+        requires is_writable
     {
-        return mutableSle_ != nullptr;
+        return sle_ != nullptr;
     }
 
     /** Returns the apply view for write operations */
     ApplyView&
     applyView() const
+        requires is_writable
     {
-        return applyView_;
+        return view_;
     }
 
+    /** Mutable dereference operators */
     STLedgerEntry*
     operator->()
+        requires is_writable
     {
-        XRPL_ASSERT(canModify(), "xrpl::WritableSLE::operator-> : can modify");
-        return mutableSle_.get();
+        XRPL_ASSERT(canModify(), "xrpl::SLEBase::operator-> : can modify");
+        return sle_.get();
     }
 
     STLedgerEntry&
     operator*()
+        requires is_writable
     {
-        XRPL_ASSERT(canModify(), "xrpl::WritableSLE::operator* : can modify");
-        return *mutableSle_;
+        XRPL_ASSERT(canModify(), "xrpl::SLEBase::operator* : can modify");
+        return *sle_;
     }
 
     void
     insert()
+        requires is_writable
     {
-        XRPL_ASSERT(canModify(), "xrpl::WritableSLE::insert : can modify");
-        applyView_.insert(mutableSle_);
+        XRPL_ASSERT(canModify(), "xrpl::SLEBase::insert : can modify");
+        view_.insert(sle_);
     }
 
     void
     erase()
+        requires is_writable
     {
-        XRPL_ASSERT(canModify(), "xrpl::WritableSLE::erase : can modify");
-        applyView_.erase(mutableSle_);
+        XRPL_ASSERT(canModify(), "xrpl::SLEBase::erase : can modify");
+        view_.erase(sle_);
     }
 
     void
     update()
+        requires is_writable
     {
-        XRPL_ASSERT(canModify(), "xrpl::WritableSLE::update : can modify");
-        applyView_.update(mutableSle_);
+        XRPL_ASSERT(canModify(), "xrpl::SLEBase::update : can modify");
+        view_.update(sle_);
     }
 
     void
     newSLE()
+        requires is_writable
     {
-        XRPL_ASSERT(!canModify(), "xrpl::WritableSLE::newSLE : mutableSle_ is not null");
-        mutableSle_ = std::make_shared<SLE>(key_);
+        XRPL_ASSERT(!canModify(), "xrpl::SLEBase::newSLE : sle_ is not null");
+        sle_ = std::make_shared<SLE>(key_);
+    }
+
+    beast::Journal
+    journal() const
+    {
+        return j_;
     }
 
 protected:
-    // Default constructor is deleted (cannot leave reference uninitialized)
-    WritableSLE() = delete;
+    SLEBase() = delete;
 
-    /** Constructor for read-write context (ApplyView) */
-    explicit WritableSLE(std::shared_ptr<SLE> sle, ApplyView& view)
-        : applyView_(view)
+    /** Constructor for read-only context */
+    explicit SLEBase(
+        SLE::const_pointer sle,
+        ReadView const& view,
+        beast::Journal j = beast::Journal{beast::Journal::getNullSink()})
+        requires(!is_writable)
+        : view_(view), sle_(std::move(sle)), j_(j)
+    {
+    }
+
+    /** Converting constructor: writable → read-only.
+     *  Enables implicit conversion from SLEBase<ApplyView> to
+     *  SLEBase<ReadView>, so functions taking ReadOnlySLE const& can
+     *  accept WritableSLE.
+     */
+    template <WritableView OtherViewT>
+    SLEBase(SLEBase<OtherViewT> const& other)
+        requires(!is_writable)
+        : view_(other.readView()), sle_(other.sle()), j_(other.journal())
+    {
+    }
+
+    /** Constructor for writable context (from existing SLE) */
+    explicit SLEBase(
+        std::shared_ptr<SLE> sle,
+        ApplyView& view,
+        beast::Journal j = beast::Journal{beast::Journal::getNullSink()})
+        requires is_writable
+        : view_(view)
         , key_(sle ? Keylet(sle->getType(), sle->key()) : Keylet(ltANY, uint256{}))
-        , mutableSle_(std::move(sle))
+        , sle_(std::move(sle))
+        , j_(j)
     {
     }
 
-    /** Constructor for read-write context (ApplyView) */
-    explicit WritableSLE(Keylet const& key, ApplyView& view)
-        : applyView_(view), key_(key), mutableSle_(applyView_.peek(key))
+    /** Constructor for writable context (peek from view by keylet) */
+    explicit SLEBase(
+        Keylet const& key,
+        ApplyView& view,
+        beast::Journal j = beast::Journal{beast::Journal::getNullSink()})
+        requires is_writable
+        : view_(view), key_(key), sle_(view_.peek(key)), j_(j)
     {
     }
 
-    ApplyView& applyView_;  // ApplyView for write contexts (first for init order)
-    Keylet const key_;
-    std::shared_ptr<SLE> mutableSle_;  // Mutable SLE for write contexts
+    view_ref_type view_;
+
+    // Keylet is only meaningful for writable views, but we conditionally
+    // include it to avoid wasting space in read-only wrappers.
+    struct Empty
+    {
+    };
+    [[no_unique_address]]
+    std::conditional_t<is_writable, Keylet, Empty> key_{};
+
+    sle_ptr_type sle_;
+    beast::Journal j_;
 };
 
 }  // namespace xrpl

include/xrpl/ledger/helpers/TokenHelpers.h

@@ -3,7 +3,6 @@
 #include <xrpl/beast/utility/Journal.h>
 #include <xrpl/ledger/ApplyView.h>
 #include <xrpl/ledger/ReadView.h>
-#include <xrpl/ledger/helpers/SLEBase.h>
 #include <xrpl/protocol/Asset.h>
 #include <xrpl/protocol/MPTIssue.h>
 #include <xrpl/protocol/Rate.h>
@@ -11,7 +10,6 @@
 #include <xrpl/protocol/TER.h>
 
 #include <initializer_list>
-#include <memory>
 #include <vector>
 
 namespace xrpl {
@@ -33,6 +31,9 @@ enum SpendableHandling { shSIMPLE_BALANCE, shFULL_BALANCE };
 
 enum class WaiveTransferFee : bool { No = false, Yes };
 
+/** Controls whether accountSend is allowed to overflow OutstandingAmount **/
+enum class AllowMPTOverflow : bool { No = false, Yes };
+
 /* Check if MPToken (for MPT) or trust line (for IOU) exists:
  * - StrongAuth - before checking if authorization is required
  * - WeakAuth
@@ -50,156 +51,82 @@ enum class AuthType { StrongAuth, WeakAuth, Legacy };
 //
 //------------------------------------------------------------------------------
 
-class TokenBase : public virtual ReadOnlySLE
-{
-public:
-    [[nodiscard]] virtual bool
-    isGlobalFrozen() const = 0;
+[[nodiscard]] bool
+isGlobalFrozen(ReadView const& view, Asset const& asset);
 
-    [[nodiscard]] virtual bool
-    isIndividualFrozen(AccountID const& account) const = 0;
+[[nodiscard]] bool
+isIndividualFrozen(ReadView const& view, AccountID const& account, Asset const& asset);
 
-    /**
-     *   isFrozen check is recursive for MPT shares in a vault, descending to
-     *   assets in the vault, up to maxAssetCheckDepth recursion depth. This is
-     *   purely defensive, as we currently do not allow such vaults to be created.
-     */
-    [[nodiscard]] virtual bool
-    isFrozen(AccountID const& account, int depth = 0) const;
+/**
+ *   isFrozen check is recursive for MPT shares in a vault, descending to
+ *   assets in the vault, up to maxAssetCheckDepth recursion depth. This is
+ *   purely defensive, as we currently do not allow such vaults to be created.
+ */
+[[nodiscard]] bool
+isFrozen(ReadView const& view, AccountID const& account, Asset const& asset, int depth = 0);
 
-    [[nodiscard]] virtual TER
-    checkFrozen(AccountID const& account) const = 0;
+[[nodiscard]] TER
+checkFrozen(ReadView const& view, AccountID const& account, Issue const& issue);
 
-    [[nodiscard]] virtual bool
-    isAnyFrozen(std::initializer_list<AccountID> const& accounts, int depth = 0) const = 0;
+[[nodiscard]] TER
+checkFrozen(ReadView const& view, AccountID const& account, MPTIssue const& mptIssue);
 
-    /**
-     *   isFrozen check is recursive for MPT shares in a vault, descending to
-     *   assets in the vault, up to maxAssetCheckDepth recursion depth. This is
-     *   purely defensive, as we currently do not allow such vaults to be created.
-     */
-    [[nodiscard]] virtual bool
-    isDeepFrozen(AccountID const& account, int depth = 0) const = 0;
+[[nodiscard]] TER
+checkFrozen(ReadView const& view, AccountID const& account, Asset const& asset);
 
-    [[nodiscard]] virtual TER
-    checkDeepFrozen(AccountID const& account) const = 0;
+[[nodiscard]] bool
+isAnyFrozen(
+    ReadView const& view,
+    std::initializer_list<AccountID> const& accounts,
+    Issue const& issue);
 
-    /** Returns the transfer fee as Rate based on the type of token
-     * @param view The ledger view
-     * @param amount The amount to transfer
-     */
-    [[nodiscard]] virtual Rate
-    transferRate() const = 0;
-    //------------------------------------------------------------------------------
-    //
-    // Account balance functions (Asset-based dispatchers)
-    //
-    //------------------------------------------------------------------------------
+[[nodiscard]] bool
+isAnyFrozen(
+    ReadView const& view,
+    std::initializer_list<AccountID> const& accounts,
+    Asset const& asset,
+    int depth = 0);
 
-    // Returns the amount an account can spend.
-    //
-    // If shSIMPLE_BALANCE is specified, this is the amount the account can spend
-    // without going into debt.
-    //
-    // If shFULL_BALANCE is specified, this is the amount the account can spend
-    // total. Specifically:
-    // * The account can go into debt if using a trust line, and the other side has
-    // a non-zero limit.
-    // * If the account is the asset issuer the limit is defined by the asset /
-    //   issuance.
-    //
-    // <-- saAmount: amount of currency held by account. May be negative.
-    virtual STAmount
-    accountHolds(
-        AccountID const& account,
-        FreezeHandling zeroIfFrozen,
-        beast::Journal j,
-        SpendableHandling includeFullBalance = shSIMPLE_BALANCE) const = 0;
+[[nodiscard]] bool
+isDeepFrozen(
+    ReadView const& view,
+    AccountID const& account,
+    MPTIssue const& mptIssue,
+    int depth = 0);
 
-    [[nodiscard]] virtual STAmount
-    accountHolds(
-        AccountID const& account,
-        FreezeHandling zeroIfFrozen,
-        AuthHandling zeroIfUnauthorized,
-        beast::Journal j,
-        SpendableHandling includeFullBalance = shSIMPLE_BALANCE) const = 0;
+/**
+ *   isFrozen check is recursive for MPT shares in a vault, descending to
+ *   assets in the vault, up to maxAssetCheckDepth recursion depth. This is
+ *   purely defensive, as we currently do not allow such vaults to be created.
+ */
+[[nodiscard]] bool
+isDeepFrozen(ReadView const& view, AccountID const& account, Asset const& asset, int depth = 0);
 
-    [[nodiscard]] virtual TER
-    canAddHolding() const = 0;
+[[nodiscard]] TER
+checkDeepFrozen(ReadView const& view, AccountID const& account, MPTIssue const& mptIssue);
 
-    //------------------------------------------------------------------------------
-    //
-    // Authorization and transfer checks (Asset-based dispatchers)
-    //
-    //------------------------------------------------------------------------------
+[[nodiscard]] TER
+checkDeepFrozen(ReadView const& view, AccountID const& account, Asset const& asset);
 
-    [[nodiscard]] virtual TER
-    requireAuth(AccountID const& account, AuthType authType = AuthType::Legacy, int depth = 0)
-        const = 0;
+//------------------------------------------------------------------------------
+//
+// Account balance functions (Asset-based dispatchers)
+//
+//------------------------------------------------------------------------------
 
-    [[nodiscard]] virtual TER
-    canTransfer(AccountID const& from, AccountID const& to) const = 0;
-
-    //------------------------------------------------------------------------------
-    //
-    // Token capability checks (Asset-based dispatchers)
-    //
-    //------------------------------------------------------------------------------
-
-    /** Check if the token issuer has enabled clawback capability.
-     * For IOUs, checks lsfAllowTrustLineClawback on issuer's AccountRoot.
-     * For MPTs, checks lsfMPTCanClawback on the issuance.
-     */
-    [[nodiscard]] virtual bool
-    canClawback() const = 0;
-
-    /** Check if the token requires authorization for holders.
-     * For IOUs, checks lsfRequireAuth on issuer's AccountRoot.
-     * For MPTs, checks lsfMPTRequireAuth on the issuance.
-     */
-    [[nodiscard]] virtual bool
-    requiresAuth() const = 0;
-
-protected:
-    TokenBase(ReadView const& view, std::shared_ptr<SLE const> sle) : ReadOnlySLE(sle, view)
-    {
-    }
-};
-
-class WritableTokenBase : public virtual TokenBase, public virtual WritableSLE
-{
-public:
-    //------------------------------------------------------------------------------
-    //
-    // Holding operations (Asset-based dispatchers)
-    //
-    //------------------------------------------------------------------------------
-
-    [[nodiscard]] virtual TER
-    addEmptyHolding(AccountID const& accountID, XRPAmount priorBalance, beast::Journal journal) = 0;
-
-    [[nodiscard]] virtual TER
-    removeEmptyHolding(AccountID const& accountID, beast::Journal journal) = 0;
-
-protected:
-    WritableTokenBase(ApplyView& view, std::shared_ptr<SLE> sle)
-        : TokenBase(view, sle), WritableSLE(sle, view)
-    {
-    }
-};
-
-std::unique_ptr<TokenBase>
-makeTokenBase(ReadView const& view, Asset const& asset);
-
-std::unique_ptr<WritableTokenBase>
-makeWritableTokenBase(ApplyView& view, Asset const& asset);
-
-// Helper function to get transfer rate from an STAmount
-[[nodiscard]] Rate
-transferRate(ReadView const& view, STAmount const& amount);
-
-// Returns the amount the specified account can spend.
-// Supports both IOU and MPT via Currency/AccountID parameters.
+// Returns the amount an account can spend.
+//
+// If shSIMPLE_BALANCE is specified, this is the amount the account can spend
+// without going into debt.
+//
+// If shFULL_BALANCE is specified, this is the amount the account can spend
+// total. Specifically:
+// * The account can go into debt if using a trust line, and the other side has
+// a non-zero limit.
+// * If the account is the asset issuer the limit is defined by the asset /
+//   issuance.
+//
+// <-- saAmount: amount of currency held by account. May be negative.
 [[nodiscard]] STAmount
 accountHolds(
     ReadView const& view,
@@ -210,8 +137,25 @@ accountHolds(
     beast::Journal j,
     SpendableHandling includeFullBalance = shSIMPLE_BALANCE);
 
-// Returns the amount the specified account can spend for a given Asset.
-// Dispatches to appropriate token wrapper based on Asset type.
+[[nodiscard]] STAmount
+accountHolds(
+    ReadView const& view,
+    AccountID const& account,
+    Issue const& issue,
+    FreezeHandling zeroIfFrozen,
+    beast::Journal j,
+    SpendableHandling includeFullBalance = shSIMPLE_BALANCE);
+
+[[nodiscard]] STAmount
+accountHolds(
+    ReadView const& view,
+    AccountID const& account,
+    MPTIssue const& mptIssue,
+    FreezeHandling zeroIfFrozen,
+    AuthHandling zeroIfUnauthorized,
+    beast::Journal j,
+    SpendableHandling includeFullBalance = shSIMPLE_BALANCE);
+
 [[nodiscard]] STAmount
 accountHolds(
     ReadView const& view,
@@ -222,6 +166,76 @@ accountHolds(
     beast::Journal j,
     SpendableHandling includeFullBalance = shSIMPLE_BALANCE);
 
+// Returns the amount an account can spend of the currency type saDefault, or
+// returns saDefault if this account is the issuer of the currency in
+// question. Should be used in favor of accountHolds when questioning how much
+// an account can spend while also allowing currency issuers to spend
+// unlimited amounts of their own currency (since they can always issue more).
+[[nodiscard]] STAmount
+accountFunds(
+    ReadView const& view,
+    AccountID const& id,
+    STAmount const& saDefault,
+    FreezeHandling freezeHandling,
+    beast::Journal j);
+
+// Overload with AuthHandling to support IOU and MPT.
+[[nodiscard]] STAmount
+accountFunds(
+    ReadView const& view,
+    AccountID const& id,
+    STAmount const& saDefault,
+    FreezeHandling freezeHandling,
+    AuthHandling authHandling,
+    beast::Journal j);
+
+/** Returns the transfer fee as Rate based on the type of token
+ * @param view The ledger view
+ * @param amount The amount to transfer
+ */
+[[nodiscard]] Rate
+transferRate(ReadView const& view, STAmount const& amount);
+
+//------------------------------------------------------------------------------
+//
+// Holding operations (Asset-based dispatchers)
+//
+//------------------------------------------------------------------------------
+
+[[nodiscard]] TER
+canAddHolding(ReadView const& view, Asset const& asset);
+
+[[nodiscard]] TER
+addEmptyHolding(
+    ApplyView& view,
+    AccountID const& accountID,
+    XRPAmount priorBalance,
+    Asset const& asset,
+    beast::Journal journal);
+
+[[nodiscard]] TER
+removeEmptyHolding(
+    ApplyView& view,
+    AccountID const& accountID,
+    Asset const& asset,
+    beast::Journal journal);
+
+//------------------------------------------------------------------------------
+//
+// Authorization and transfer checks (Asset-based dispatchers)
+//
+//------------------------------------------------------------------------------
+
+[[nodiscard]] TER
+requireAuth(
+    ReadView const& view,
+    Asset const& asset,
+    AccountID const& account,
+    AuthType authType = AuthType::Legacy);
+
+[[nodiscard]] TER
+canTransfer(ReadView const& view, Asset const& asset, AccountID const& from, AccountID const& to);
+
 //------------------------------------------------------------------------------
 //
 // Money Transfers (Asset-based dispatchers)
@@ -234,11 +248,11 @@ accountHolds(
 // bCheckIssuer : normally require issuer to be involved.
 // [[nodiscard]] // nodiscard commented out so DirectStep.cpp compiles.
 
-/** Calls static rippleCreditIOU if saAmount represents Issue.
- * Calls static rippleCreditMPT if saAmount represents MPTIssue.
+/** Calls static directSendNoFeeIOU if saAmount represents Issue.
+ * Calls static directSendNoFeeMPT if saAmount represents MPTIssue.
  */
 TER
-rippleCredit(
+directSendNoFee(
     ApplyView& view,
     AccountID const& uSenderID,
     AccountID const& uReceiverID,
@@ -256,7 +270,8 @@ accountSend(
     AccountID const& to,
     STAmount const& saAmount,
     beast::Journal j,
-    WaiveTransferFee waiveFee = WaiveTransferFee::No);
+    WaiveTransferFee waiveFee = WaiveTransferFee::No,
+    AllowMPTOverflow allowOverflow = AllowMPTOverflow::No);
 
 using MultiplePaymentDestinations = std::vector<std::pair<AccountID, Number>>;
 /** Like accountSend, except one account is sending multiple payments (with the

include/xrpl/ledger/helpers/VaultHelpers.h

@@ -1,6 +1,5 @@
 #pragma once
 
-#include <xrpl/ledger/helpers/MPTokenHelpers.h>
 #include <xrpl/protocol/STAmount.h>
 #include <xrpl/protocol/STLedgerEntry.h>
 
@@ -22,7 +21,7 @@ namespace xrpl {
 [[nodiscard]] std::optional<STAmount>
 assetsToSharesDeposit(
     std::shared_ptr<SLE const> const& vault,
-    MPTokenIssuance const& issuance,
+    std::shared_ptr<SLE const> const& issuance,
     STAmount const& assets);
 
 /** From the perspective of a vault, return the number of assets to take from
@@ -38,7 +37,7 @@ assetsToSharesDeposit(
 [[nodiscard]] std::optional<STAmount>
 sharesToAssetsDeposit(
     std::shared_ptr<SLE const> const& vault,
-    MPTokenIssuance const& issuance,
+    std::shared_ptr<SLE const> const& issuance,
     STAmount const& shares);
 
 /** Controls whether to truncate shares instead of rounding. */
@@ -59,7 +58,7 @@ enum class TruncateShares : bool { no = false, yes = true };
 [[nodiscard]] std::optional<STAmount>
 assetsToSharesWithdraw(
     std::shared_ptr<SLE const> const& vault,
-    MPTokenIssuance const& issuance,
+    std::shared_ptr<SLE const> const& issuance,
     STAmount const& assets,
     TruncateShares truncate = TruncateShares::no);
 
@@ -76,7 +75,7 @@ assetsToSharesWithdraw(
 [[nodiscard]] std::optional<STAmount>
 sharesToAssetsWithdraw(
     std::shared_ptr<SLE const> const& vault,
-    MPTokenIssuance const& issuance,
+    std::shared_ptr<SLE const> const& issuance,
     STAmount const& shares);
 
 }  // namespace xrpl

include/xrpl/nodestore/README.md

@@ -51,7 +51,7 @@ A blob containing the payload. Stored in the following format.
 ---
 
 The `NodeStore` provides an interface that stores, in a persistent database, a
-collection of NodeObjects that rippled uses as its primary representation of
+collection of NodeObjects that xrpld uses as its primary representation of
 ledger entries. All ledger entries are stored as NodeObjects and as such, need
 to be persisted between launches. If a NodeObject is accessed and is not in
 memory, it will be retrieved from the database.
@@ -110,7 +110,7 @@ The `NodeStore.Timing` test is used to execute a set of read/write workloads to
 compare current available nodestore backends. It can be executed with:
 
 ```
-$rippled --unittest=NodeStoreTiming
+$xrpld --unittest=NodeStoreTiming
 ```
 
 It is also possible to use alternate DB config params by passing config strings
@@ -143,10 +143,10 @@ Through various executions and profiling some conclusions are presented below.
   just after ledger close, then that would provide similar, but more predictable
   guarantees. It would also remove an unneeded thread and unnecessary memory
   usage. An alternative point of view is that because there will always be many
-  other rippled instances running there is no need for such guarantees. The nodes
+  other xrpld instances running there is no need for such guarantees. The nodes
   will always be available from another peer.
 
-- Lookup in a block was previously using binary search. With rippled's use case
+- Lookup in a block was previously using binary search. With xrpld's use case
   it is highly unlikely that two adjacent key/values will ever be requested one
   after the other. Therefore hash indexing of blocks makes much more sense.
   Rocksdb has a number of options for hash indexing both memtables and blocks and

include/xrpl/nodestore/Scheduler.h

@@ -16,7 +16,7 @@ struct FetchReport
     {
     }
 
-    std::chrono::milliseconds elapsed;
+    std::chrono::milliseconds elapsed{};
     FetchType const fetchType;
     bool wasFound = false;
 };

include/xrpl/nodestore/detail/BatchWriter.h

@@ -71,8 +71,8 @@ private:
     Scheduler& m_scheduler;
     LockType mWriteMutex;
     CondvarType mWriteCondition;
-    int mWriteLoad;
-    bool mWritePending;
+    int mWriteLoad{0};
+    bool mWritePending{false};
     Batch mWriteSet;
 };
 

include/xrpl/nodestore/detail/EncodedBlob.h

@@ -35,7 +35,7 @@ namespace NodeStore {
 class EncodedBlob
 {
     /** The 32-byte key of the serialized object. */
-    std::array<std::uint8_t, 32> key_;
+    std::array<std::uint8_t, 32> key_{};
 
     /** A pre-allocated buffer for the serialized object.
 
@@ -43,7 +43,8 @@ class EncodedBlob
          1024 more bytes. The precise size is calculated automatically
          at compile time so as to avoid wasting space on padding bytes.
      */
-    std::array<std::uint8_t, boost::alignment::align_up(9 + 1024, alignof(std::uint32_t))> payload_;
+    std::array<std::uint8_t, boost::alignment::align_up(9 + 1024, alignof(std::uint32_t))>
+        payload_{};
 
     /** The size of the serialized data. */
     std::uint32_t size_;

include/xrpl/nodestore/detail/codec.h

@@ -56,7 +56,7 @@ lz4_compress(void const* in, std::size_t in_size, BufferFactory&& bf)
     using std::runtime_error;
     using namespace nudb::detail;
     std::pair<void const*, std::size_t> result;
-    std::array<std::uint8_t, varint_traits<std::size_t>::max> vi;
+    std::array<std::uint8_t, varint_traits<std::size_t>::max> vi{};
     auto const n = write_varint(vi.data(), in_size);
     auto const out_max = LZ4_compressBound(in_size);
     std::uint8_t* out = reinterpret_cast<std::uint8_t*>(bf(n + out_max));
@@ -88,7 +88,7 @@ nodeobject_decompress(void const* in, std::size_t in_size, BufferFactory&& bf)
     using namespace nudb::detail;
 
     std::uint8_t const* p = reinterpret_cast<std::uint8_t const*>(in);
-    std::size_t type;
+    std::size_t type = 0;
     auto const vn = read_varint(p, in_size, type);
     if (vn == 0)
         Throw<std::runtime_error>("nodeobject decompress");
@@ -117,7 +117,7 @@ nodeobject_decompress(void const* in, std::size_t in_size, BufferFactory&& bf)
                     "nodeobject codec v1: short inner node size: " + std::string("in_size = ") +
                     std::to_string(in_size) + " hs = " + std::to_string(hs));
             istream is(p, in_size);
-            std::uint16_t mask;
+            std::uint16_t mask = 0;
             read<std::uint16_t>(is, mask);  // Mask
             in_size -= hs;
             result.second = 525;
@@ -196,10 +196,10 @@ nodeobject_compress(void const* in, std::size_t in_size, BufferFactory&& bf)
     if (in_size == 525)
     {
         istream is(in, in_size);
-        std::uint32_t index;
-        std::uint32_t unused;
-        std::uint8_t kind;
-        std::uint32_t prefix;
+        std::uint32_t index = 0;
+        std::uint32_t unused = 0;
+        std::uint8_t kind = 0;
+        std::uint32_t prefix = 0;
         read<std::uint32_t>(is, index);
         read<std::uint32_t>(is, unused);
         read<std::uint8_t>(is, kind);
@@ -208,7 +208,7 @@ nodeobject_compress(void const* in, std::size_t in_size, BufferFactory&& bf)
         {
             std::size_t n = 0;
             std::uint16_t mask = 0;
-            std::array<std::uint8_t, 512> vh;
+            std::array<std::uint8_t, 512> vh{};
             for (unsigned bit = 0x8000; bit; bit >>= 1)
             {
                 void const* const h = is(32);
@@ -247,7 +247,7 @@ nodeobject_compress(void const* in, std::size_t in_size, BufferFactory&& bf)
         }
     }
 
-    std::array<std::uint8_t, varint_traits<std::size_t>::max> vi;
+    std::array<std::uint8_t, varint_traits<std::size_t>::max> vi{};
 
     constexpr std::size_t codecType = 1;
     auto const vn = write_varint(vi.data(), codecType);
@@ -257,7 +257,7 @@ nodeobject_compress(void const* in, std::size_t in_size, BufferFactory&& bf)
         // case 0 was uncompressed data; we always compress now.
         case 1:  // lz4
         {
-            std::uint8_t* p;
+            std::uint8_t* p = nullptr;
             auto const lzr = NodeStore::lz4_compress(in, in_size, [&p, &vn, &bf](std::size_t n) {
                 p = reinterpret_cast<std::uint8_t*>(bf(vn + n));
                 return p + vn;
@@ -287,10 +287,10 @@ filter_inner(void* in, std::size_t in_size)
     if (in_size == 525)
     {
         istream is(in, in_size);
-        std::uint32_t index;
-        std::uint32_t unused;
-        std::uint8_t kind;
-        std::uint32_t prefix;
+        std::uint32_t index = 0;
+        std::uint32_t unused = 0;
+        std::uint8_t kind = 0;
+        std::uint32_t prefix = 0;
         read<std::uint32_t>(is, index);
         read<std::uint32_t>(is, unused);
         read<std::uint8_t>(is, kind);

include/xrpl/nodestore/detail/varint.h

@@ -82,6 +82,7 @@ template <class = void>
 std::size_t
 write_varint(void* p0, std::size_t v)
 {
+    // NOLINTNEXTLINE(misc-const-correctness)
     std::uint8_t* p = reinterpret_cast<std::uint8_t*>(p0);
     do
     {

include/xrpl/proto/org/xrpl/rpc/v1/README.md

@@ -1,8 +1,8 @@
 # Protocol buffer definitions for gRPC
 
-This folder contains the protocol buffer definitions used by the rippled gRPC API.
+This folder contains the protocol buffer definitions used by the xrpld gRPC API.
 The gRPC API attempts to mimic the JSON/Websocket API as much as possible.
-As of April 2020, the gRPC API supports a subset of the full rippled API:
+As of April 2020, the gRPC API supports a subset of the full xrpld API:
 tx, account_tx, account_info, fee and submit.
 
 ### Making Changes
@@ -63,7 +63,7 @@ templated `CallData` class in GRPCServerImpl::setupListeners(). The template
 parameters should be the request type and the response type.
 
 Finally, define the handler itself in the appropriate file under the
-src/ripple/rpc/handlers folder. If the method already has a JSON/Websocket
+src/xrpld/rpc/handlers folder. If the method already has a JSON/Websocket
 equivalent, write the gRPC handler in the same file, and abstract common logic
 into helper functions (see Tx.cpp or AccountTx.cpp for an example).
 

include/xrpl/proto/xrpl.proto

@@ -36,7 +36,7 @@ enum MessageType {
 
 /* Provides the current ephemeral key for a validator. */
 message TMManifest {
-  // A Manifest object in the Ripple serialization format.
+  // A Manifest object in the XRPL serialization format.
   required bytes stobject = 1;
 }
 

include/xrpl/protocol/AMMCore.h

@@ -2,7 +2,7 @@
 
 #include <xrpl/basics/Number.h>
 #include <xrpl/protocol/AccountID.h>
-#include <xrpl/protocol/Issue.h>
+#include <xrpl/protocol/Asset.h>
 #include <xrpl/protocol/TER.h>
 #include <xrpl/protocol/UintTypes.h>
 
@@ -31,12 +31,12 @@ class Rules;
 /** Calculate Liquidity Provider Token (LPT) Currency.
  */
 Currency
-ammLPTCurrency(Currency const& cur1, Currency const& cur2);
+ammLPTCurrency(Asset const& asset1, Asset const& asset2);
 
 /** Calculate LPT Issue from AMM asset pair.
  */
 Issue
-ammLPTIssue(Currency const& cur1, Currency const& cur2, AccountID const& ammAccountID);
+ammLPTIssue(Asset const& asset1, Asset const& asset2, AccountID const& ammAccountID);
 
 /** Validate the amount.
  * If validZero is false and amount is beast::zero then invalid amount.
@@ -46,19 +46,19 @@ ammLPTIssue(Currency const& cur1, Currency const& cur2, AccountID const& ammAcco
 NotTEC
 invalidAMMAmount(
     STAmount const& amount,
-    std::optional<std::pair<Issue, Issue>> const& pair = std::nullopt,
+    std::optional<std::pair<Asset, Asset>> const& pair = std::nullopt,
     bool validZero = false);
 
 NotTEC
 invalidAMMAsset(
-    Issue const& issue,
-    std::optional<std::pair<Issue, Issue>> const& pair = std::nullopt);
+    Asset const& asset,
+    std::optional<std::pair<Asset, Asset>> const& pair = std::nullopt);
 
 NotTEC
 invalidAMMAssetPair(
-    Issue const& issue1,
-    Issue const& issue2,
-    std::optional<std::pair<Issue, Issue>> const& pair = std::nullopt);
+    Asset const& asset1,
+    Asset const& asset2,
+    std::optional<std::pair<Asset, Asset>> const& pair = std::nullopt);
 
 /** Get time slot of the auction slot.
  */

include/xrpl/protocol/AccountID.h

@@ -2,7 +2,7 @@
 
 #include <xrpl/protocol/tokens.h>
 // VFALCO Uncomment when the header issues are resolved
-// #include <ripple/protocol/PublicKey.h>
+// #include <xrpl/protocol/PublicKey.h>
 #include <xrpl/basics/UnorderedContainers.h>
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/json/json_value.h>

include/xrpl/protocol/AmountConversions.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <xrpl/protocol/IOUAmount.h>
+#include <xrpl/protocol/Protocol.h>
 #include <xrpl/protocol/STAmount.h>
 #include <xrpl/protocol/XRPAmount.h>
 
@@ -9,11 +10,12 @@
 namespace xrpl {
 
 inline STAmount
-toSTAmount(IOUAmount const& iou, Issue const& iss)
+toSTAmount(IOUAmount const& iou, Asset const& asset)
 {
+    XRPL_ASSERT(asset.holds<Issue>(), "xrpl::toSTAmount : is Issue");
     bool const isNeg = iou.signum() < 0;
     std::uint64_t const umant = isNeg ? -iou.mantissa() : iou.mantissa();
-    return STAmount(iss, umant, iou.exponent(), isNeg, STAmount::unchecked());
+    return STAmount(asset, umant, iou.exponent(), isNeg, STAmount::unchecked());
 }
 
 inline STAmount
@@ -31,12 +33,25 @@ toSTAmount(XRPAmount const& xrp)
 }
 
 inline STAmount
-toSTAmount(XRPAmount const& xrp, Issue const& iss)
+toSTAmount(XRPAmount const& xrp, Asset const& asset)
 {
-    XRPL_ASSERT(isXRP(iss.account) && isXRP(iss.currency), "xrpl::toSTAmount : is XRP");
+    XRPL_ASSERT(isXRP(asset), "xrpl::toSTAmount : is XRP");
     return toSTAmount(xrp);
 }
 
+inline STAmount
+toSTAmount(MPTAmount const& mpt)
+{
+    return STAmount(mpt, noMPT());
+}
+
+inline STAmount
+toSTAmount(MPTAmount const& mpt, Asset const& asset)
+{
+    XRPL_ASSERT(asset.holds<MPTIssue>(), "xrpl::toSTAmount : is MPT");
+    return STAmount(mpt, asset.get<MPTIssue>());
+}
+
 template <class T>
 T
 toAmount(STAmount const& amt) = delete;
@@ -76,6 +91,21 @@ toAmount<XRPAmount>(STAmount const& amt)
     return XRPAmount(sMant);
 }
 
+template <>
+inline MPTAmount
+toAmount<MPTAmount>(STAmount const& amt)
+{
+    XRPL_ASSERT(
+        amt.holds<MPTIssue>() && amt.mantissa() <= maxMPTokenAmount && amt.exponent() == 0,
+        "xrpl::toAmount<MPTAmount> : maximum mantissa");
+    if (amt.mantissa() > maxMPTokenAmount || amt.exponent() != 0)
+        Throw<std::runtime_error>("toAmount<MPTAmount>: invalid mantissa or exponent");
+    bool const isNeg = amt.negative();
+    std::int64_t const sMant = isNeg ? -std::int64_t(amt.mantissa()) : amt.mantissa();
+
+    return MPTAmount(sMant);
+}
+
 template <class T>
 T
 toAmount(IOUAmount const& amt) = delete;
@@ -98,23 +128,36 @@ toAmount<XRPAmount>(XRPAmount const& amt)
     return amt;
 }
 
+template <class T>
+T
+toAmount(MPTAmount const& amt) = delete;
+
+template <>
+inline MPTAmount
+toAmount<MPTAmount>(MPTAmount const& amt)
+{
+    return amt;
+}
+
 template <typename T>
 T
-toAmount(Issue const& issue, Number const& n, Number::rounding_mode mode = Number::getround())
+toAmount(Asset const& asset, Number const& n, Number::rounding_mode mode = Number::getround())
 {
-    saveNumberRoundMode rm(Number::getround());
-    if (isXRP(issue))
+    saveNumberRoundMode const rm(Number::getround());
+    if (isXRP(asset))
         Number::setround(mode);
 
     if constexpr (std::is_same_v<IOUAmount, T>)
         return IOUAmount(n);
     else if constexpr (std::is_same_v<XRPAmount, T>)
         return XRPAmount(static_cast<std::int64_t>(n));
+    else if constexpr (std::is_same_v<MPTAmount, T>)
+        return MPTAmount(static_cast<std::int64_t>(n));
     else if constexpr (std::is_same_v<STAmount, T>)
     {
-        if (isXRP(issue))
-            return STAmount(issue, static_cast<std::int64_t>(n));
-        return STAmount(issue, n);
+        if (isXRP(asset))
+            return STAmount(asset, static_cast<std::int64_t>(n));
+        return STAmount(asset, n);
     }
     else
     {
@@ -125,17 +168,23 @@ toAmount(Issue const& issue, Number const& n, Number::rounding_mode mode = Numbe
 
 template <typename T>
 T
-toMaxAmount(Issue const& issue)
+toMaxAmount(Asset const& asset)
 {
     if constexpr (std::is_same_v<IOUAmount, T>)
         return IOUAmount(STAmount::cMaxValue, STAmount::cMaxOffset);
     else if constexpr (std::is_same_v<XRPAmount, T>)
         return XRPAmount(static_cast<std::int64_t>(STAmount::cMaxNativeN));
+    else if constexpr (std::is_same_v<MPTAmount, T>)
+        return MPTAmount(maxMPTokenAmount);
     else if constexpr (std::is_same_v<STAmount, T>)
     {
-        if (isXRP(issue))
-            return STAmount(issue, static_cast<std::int64_t>(STAmount::cMaxNativeN));
-        return STAmount(issue, STAmount::cMaxValue, STAmount::cMaxOffset);
+        return asset.visit(
+            [](Issue const& issue) {
+                if (isXRP(issue))
+                    return STAmount(issue, static_cast<std::int64_t>(STAmount::cMaxNativeN));
+                return STAmount(issue, STAmount::cMaxValue, STAmount::cMaxOffset);
+            },
+            [](MPTIssue const& issue) { return STAmount(issue, maxMPTokenAmount); });
     }
     else
     {
@@ -145,21 +194,23 @@ toMaxAmount(Issue const& issue)
 }
 
 inline STAmount
-toSTAmount(Issue const& issue, Number const& n, Number::rounding_mode mode = Number::getround())
+toSTAmount(Asset const& asset, Number const& n, Number::rounding_mode mode = Number::getround())
 {
-    return toAmount<STAmount>(issue, n, mode);
+    return toAmount<STAmount>(asset, n, mode);
 }
 
 template <typename T>
-Issue
-getIssue(T const& amt)
+Asset
+getAsset(T const& amt)
 {
     if constexpr (std::is_same_v<IOUAmount, T>)
         return noIssue();
     else if constexpr (std::is_same_v<XRPAmount, T>)
         return xrpIssue();
+    else if constexpr (std::is_same_v<MPTAmount, T>)
+        return noMPT();
     else if constexpr (std::is_same_v<STAmount, T>)
-        return amt.issue();
+        return amt.asset();
     else
     {
         constexpr bool alwaysFalse = !std::is_same_v<T, T>;
@@ -175,6 +226,8 @@ get(STAmount const& a)
         return a.iou();
     else if constexpr (std::is_same_v<XRPAmount, T>)
         return a.xrp();
+    else if constexpr (std::is_same_v<MPTAmount, T>)
+        return a.mpt();
     else if constexpr (std::is_same_v<STAmount, T>)
         return a;
     else

include/xrpl/protocol/Asset.h

@@ -2,20 +2,37 @@
 
 #include <xrpl/basics/Number.h>
 #include <xrpl/basics/base_uint.h>
+#include <xrpl/protocol/Concepts.h>
 #include <xrpl/protocol/Issue.h>
 #include <xrpl/protocol/MPTIssue.h>
+#include <xrpl/protocol/Rules.h>
 
 namespace xrpl {
 
-class Asset;
 class STAmount;
 
-template <typename TIss>
-concept ValidIssueType = std::is_same_v<TIss, Issue> || std::is_same_v<TIss, MPTIssue>;
+template <typename T>
+    requires(
+        std::is_same_v<T, XRPAmount> || std::is_same_v<T, IOUAmount> ||
+        std::is_same_v<T, MPTAmount>)
+struct AmountType
+{
+    using amount_type = T;
+};
 
-template <typename A>
-concept AssetType = std::is_convertible_v<A, Asset> || std::is_convertible_v<A, Issue> ||
-    std::is_convertible_v<A, MPTIssue> || std::is_convertible_v<A, MPTID>;
+/* Used to check for an asset with either badCurrency()
+ * or MPT with 0 account.
+ */
+struct BadAsset
+{
+};
+
+inline BadAsset const&
+badAsset()
+{
+    static BadAsset const a;
+    return a;
+}
 
 /* Asset is an abstraction of three different issue types: XRP, IOU, MPT.
  * For historical reasons, two issue types XRP and IOU are wrapped in Issue
@@ -26,6 +43,9 @@ class Asset
 {
 public:
     using value_type = std::variant<Issue, MPTIssue>;
+    using token_type = std::variant<Currency, MPTID>;
+    using AmtType =
+        std::variant<AmountType<XRPAmount>, AmountType<IOUAmount>, AmountType<MPTAmount>>;
 
 private:
     value_type issue_;
@@ -69,36 +89,42 @@ public:
     constexpr value_type const&
     value() const;
 
+    constexpr token_type
+    token() const;
+
     void
     setJson(Json::Value& jv) const;
 
     STAmount
     operator()(Number const&) const;
 
-    bool
+    constexpr AmtType
+    getAmountType() const;
+
+    // Custom, generic visit implementation
+    template <typename... Visitors>
+    constexpr auto
+    visit(Visitors&&... visitors) const -> decltype(auto)
+    {
+        // Simple delegation to the reusable utility, passing the internal
+        // variant data.
+        return detail::visit(issue_, std::forward<Visitors>(visitors)...);
+    }
+
+    constexpr bool
     native() const
     {
-        return std::visit(
-            [&]<ValidIssueType TIss>(TIss const& issue) {
-                if constexpr (std::is_same_v<TIss, Issue>)
-                    return issue.native();
-                if constexpr (std::is_same_v<TIss, MPTIssue>)
-                    return false;
-            },
-            issue_);
+        return visit(
+            [&](Issue const& issue) { return issue.native(); },
+            [&](MPTIssue const&) { return false; });
     }
 
     bool
     integral() const
     {
-        return std::visit(
-            [&]<ValidIssueType TIss>(TIss const& issue) {
-                if constexpr (std::is_same_v<TIss, Issue>)
-                    return issue.native();
-                if constexpr (std::is_same_v<TIss, MPTIssue>)
-                    return true;
-            },
-            issue_);
+        return visit(
+            [&](Issue const& issue) { return issue.native(); },
+            [&](MPTIssue const&) { return true; });
     }
 
     friend constexpr bool
@@ -110,6 +136,10 @@ public:
     friend constexpr bool
     operator==(Currency const& lhs, Asset const& rhs);
 
+    // rhs is either badCurrency() or MPT issuer is 0
+    friend constexpr bool
+    operator==(BadAsset const& lhs, Asset const& rhs);
+
     /** Return true if both assets refer to the same currency (regardless of
      * issuer) or MPT issuance. Otherwise return false.
      */
@@ -117,6 +147,12 @@ public:
     equalTokens(Asset const& lhs, Asset const& rhs);
 };
 
+template <ValidIssueType TIss>
+constexpr bool is_issue_v = std::is_same_v<TIss, Issue>;
+
+template <ValidIssueType TIss>
+constexpr bool is_mptissue_v = std::is_same_v<TIss, MPTIssue>;
+
 inline Json::Value
 to_json(Asset const& asset)
 {
@@ -156,6 +192,29 @@ Asset::value() const
     return issue_;
 }
 
+constexpr Asset::token_type
+Asset::token() const
+{
+    return visit(
+        [&](Issue const& issue) -> Asset::token_type { return issue.currency; },
+        [&](MPTIssue const& issue) -> Asset::token_type { return issue.getMptID(); });
+}
+
+constexpr Asset::AmtType
+Asset::getAmountType() const
+{
+    return visit(
+        [&](Issue const& issue) -> Asset::AmtType {
+            constexpr AmountType<XRPAmount> xrp;
+            constexpr AmountType<IOUAmount> iou;
+            return native() ? AmtType(xrp) : AmtType(iou);
+        },
+        [&](MPTIssue const& issue) -> Asset::AmtType {
+            constexpr AmountType<MPTAmount> mpt;
+            return AmtType(mpt);
+        });
+}
+
 constexpr bool
 operator==(Asset const& lhs, Asset const& rhs)
 {
@@ -177,7 +236,7 @@ operator<=>(Asset const& lhs, Asset const& rhs)
         []<ValidIssueType TLhs, ValidIssueType TRhs>(TLhs const& lhs_, TRhs const& rhs_) {
             if constexpr (std::is_same_v<TLhs, TRhs>)
                 return std::weak_ordering(lhs_ <=> rhs_);
-            else if constexpr (std::is_same_v<TLhs, Issue> && std::is_same_v<TRhs, MPTIssue>)
+            else if constexpr (is_issue_v<TLhs> && is_mptissue_v<TRhs>)
                 return std::weak_ordering::greater;
             else
                 return std::weak_ordering::less;
@@ -189,7 +248,17 @@ operator<=>(Asset const& lhs, Asset const& rhs)
 constexpr bool
 operator==(Currency const& lhs, Asset const& rhs)
 {
-    return rhs.holds<Issue>() && rhs.get<Issue>().currency == lhs;
+    return rhs.visit(
+        [&](Issue const& issue) { return issue.currency == lhs; },
+        [](MPTIssue const& issue) { return false; });
+}
+
+constexpr bool
+operator==(BadAsset const&, Asset const& rhs)
+{
+    return rhs.visit(
+        [](Issue const& issue) -> bool { return badCurrency() == issue.currency; },
+        [](MPTIssue const& issue) -> bool { return issue.getIssuer() == xrpAccount(); });
 }
 
 constexpr bool
@@ -223,4 +292,36 @@ validJSONAsset(Json::Value const& jv);
 Asset
 assetFromJson(Json::Value const& jv);
 
+Json::Value
+to_json(Asset const& asset);
+
+inline bool
+isConsistent(Asset const& asset)
+{
+    return asset.visit(
+        [](Issue const& issue) { return isConsistent(issue); },
+        [](MPTIssue const&) { return true; });
+}
+
+inline bool
+validAsset(Asset const& asset)
+{
+    return asset.visit(
+        [](Issue const& issue) { return isConsistent(issue) && issue.currency != badCurrency(); },
+        [](MPTIssue const& issue) { return issue.getIssuer() != xrpAccount(); });
+}
+
+template <class Hasher>
+void
+hash_append(Hasher& h, Asset const& r)
+{
+    using beast::hash_append;
+    r.visit(
+        [&](Issue const& issue) { hash_append(h, issue); },
+        [&](MPTIssue const& issue) { hash_append(h, issue); });
+}
+
+std::ostream&
+operator<<(std::ostream& os, Asset const& x);
+
 }  // namespace xrpl

include/xrpl/protocol/Book.h

@@ -2,7 +2,7 @@
 
 #include <xrpl/basics/CountedObject.h>
 #include <xrpl/basics/base_uint.h>
-#include <xrpl/protocol/Issue.h>
+#include <xrpl/protocol/Asset.h>
 
 #include <boost/utility/base_from_member.hpp>
 
@@ -15,15 +15,15 @@ namespace xrpl {
 class Book final : public CountedObject<Book>
 {
 public:
-    Issue in;
-    Issue out;
+    Asset in;
+    Asset out;
     std::optional<uint256> domain;
 
     Book()
     {
     }
 
-    Book(Issue const& in_, Issue const& out_, std::optional<uint256> const& domain_)
+    Book(Asset const& in_, Asset const& out_, std::optional<uint256> const& domain_)
         : in(in_), out(out_), domain(domain_)
     {
     }
@@ -112,16 +112,67 @@ public:
     }
 };
 
+template <>
+struct hash<xrpl::MPTIssue> : private boost::base_from_member<std::hash<xrpl::MPTID>, 0>
+{
+private:
+    using id_hash_type = boost::base_from_member<std::hash<xrpl::MPTID>, 0>;
+
+public:
+    explicit hash() = default;
+
+    using value_type = std::size_t;
+    using argument_type = xrpl::MPTIssue;
+
+    value_type
+    operator()(argument_type const& value) const
+    {
+        value_type const result(id_hash_type::member(value.getMptID()));
+        return result;
+    }
+};
+
+template <>
+struct hash<xrpl::Asset>
+{
+private:
+    using value_type = std::size_t;
+    using argument_type = xrpl::Asset;
+
+    using issue_hasher = std::hash<xrpl::Issue>;
+    using mptissue_hasher = std::hash<xrpl::MPTIssue>;
+
+    issue_hasher m_issue_hasher;
+    mptissue_hasher m_mptissue_hasher;
+
+public:
+    explicit hash() = default;
+
+    value_type
+    operator()(argument_type const& asset) const
+    {
+        return asset.visit(
+            [&](xrpl::Issue const& issue) {
+                value_type const result(m_issue_hasher(issue));
+                return result;
+            },
+            [&](xrpl::MPTIssue const& issue) {
+                value_type const result(m_mptissue_hasher(issue));
+                return result;
+            });
+    }
+};
+
 //------------------------------------------------------------------------------
 
 template <>
 struct hash<xrpl::Book>
 {
 private:
-    using issue_hasher = std::hash<xrpl::Issue>;
+    using asset_hasher = std::hash<xrpl::Asset>;
     using uint256_hasher = xrpl::uint256::hasher;
 
-    issue_hasher m_issue_hasher;
+    asset_hasher m_asset_hasher;
     uint256_hasher m_uint256_hasher;
 
 public:
@@ -133,8 +184,8 @@ public:
     value_type
     operator()(argument_type const& value) const
     {
-        value_type result(m_issue_hasher(value.in));
-        boost::hash_combine(result, m_issue_hasher(value.out));
+        value_type result(m_asset_hasher(value.in));
+        boost::hash_combine(result, m_asset_hasher(value.out));
 
         if (value.domain)
             boost::hash_combine(result, m_uint256_hasher(*value.domain));
@@ -159,6 +210,22 @@ struct hash<xrpl::Issue> : std::hash<xrpl::Issue>
     // using Base::Base; // inherit ctors
 };
 
+template <>
+struct hash<xrpl::MPTIssue> : std::hash<xrpl::MPTIssue>
+{
+    explicit hash() = default;
+
+    using Base = std::hash<xrpl::MPTIssue>;
+};
+
+template <>
+struct hash<xrpl::Asset> : std::hash<xrpl::Asset>
+{
+    explicit hash() = default;
+
+    using Base = std::hash<xrpl::Asset>;
+};
+
 template <>
 struct hash<xrpl::Book> : std::hash<xrpl::Book>
 {

include/xrpl/protocol/BuildInfo.h

@@ -33,7 +33,7 @@ getFullVersionString();
     X: 16 bits identifying the particular implementation
     Y: 48 bits of data specific to the implementation
 
-    The rippled-specific format (implementation ID is: 0x18 0x3B) is:
+    The xrpld-specific format (implementation ID is: 0x18 0x3B) is:
 
     00011000-00111011-MMMMMMMM-mmmmmmmm-pppppppp-TTNNNNNN-00000000-00000000
 
@@ -55,23 +55,23 @@ encodeSoftwareVersion(std::string_view versionStr);
 std::uint64_t
 getEncodedVersion();
 
-/** Check if the encoded software version is a rippled software version.
+/** Check if the encoded software version is an xrpld software version.
 
     @param version another node's encoded software version
-    @return true if the version is a rippled software version, false otherwise
+    @return true if the version is an xrpld software version, false otherwise
 */
 bool
-isRippledVersion(std::uint64_t version);
+isXrpldVersion(std::uint64_t version);
 
-/** Check if the version is newer than the local node's rippled software
+/** Check if the version is newer than the local node's xrpld software
     version.
 
     @param version another node's encoded software version
-    @return true if the version is newer than the local node's rippled software
+    @return true if the version is newer than the local node's xrpld software
         version, false otherwise.
 
     @note This function only understands version numbers that are generated by
-        rippled. Please see the encodeSoftwareVersion() function for detail.
+        xrpld. Please see the encodeSoftwareVersion() function for detail.
 */
 bool
 isNewerVersion(std::uint64_t version);

include/xrpl/protocol/Concepts.h

@@ -0,0 +1,86 @@
+#pragma once
+
+#include <xrpl/protocol/UintTypes.h>
+
+#include <type_traits>
+
+namespace xrpl {
+
+class STAmount;
+class Asset;
+class Issue;
+class MPTIssue;
+class IOUAmount;
+class XRPAmount;
+class MPTAmount;
+
+template <typename A>
+concept StepAmount =
+    std::is_same_v<A, XRPAmount> || std::is_same_v<A, IOUAmount> || std::is_same_v<A, MPTAmount>;
+
+template <typename TIss>
+concept ValidIssueType = std::is_same_v<TIss, Issue> || std::is_same_v<TIss, MPTIssue>;
+
+template <typename A>
+concept AssetType = std::is_convertible_v<A, Asset> || std::is_convertible_v<A, Issue> ||
+    std::is_convertible_v<A, MPTIssue> || std::is_convertible_v<A, MPTID>;
+
+template <typename T>
+concept ValidPathAsset = (std::is_same_v<T, Currency> || std::is_same_v<T, MPTID>);
+
+template <class TTakerPays, class TTakerGets>
+concept ValidTaker =
+    ((std::is_same_v<TTakerPays, IOUAmount> || std::is_same_v<TTakerPays, XRPAmount> ||
+      std::is_same_v<TTakerPays, MPTAmount>) &&
+     (std::is_same_v<TTakerGets, IOUAmount> || std::is_same_v<TTakerGets, XRPAmount> ||
+      std::is_same_v<TTakerGets, MPTAmount>) &&
+     (!std::is_same_v<TTakerPays, XRPAmount> || !std::is_same_v<TTakerGets, XRPAmount>));
+
+namespace detail {
+
+// This template combines multiple callable objects (lambdas) into a single
+// object that std::visit can use for overload resolution.
+template <typename... Ts>
+struct CombineVisitors : Ts...
+{
+    // Bring all operator() overloads from base classes into this scope.
+    // It's the mechanism that makes the CombineVisitors struct function
+    // as a single callable object with multiple overloads.
+    using Ts::operator()...;
+
+    // Perfect forwarding constructor to correctly initialize the base class
+    // lambdas
+    constexpr CombineVisitors(Ts&&... ts) : Ts(std::forward<Ts>(ts))...
+    {
+    }
+};
+
+// This function forces function template argument deduction, which is more
+// robust than class template argument deduction (CTAD) via the deduction guide.
+template <typename... Ts>
+constexpr CombineVisitors<std::decay_t<Ts>...>
+make_combine_visitors(Ts&&... ts)
+{
+    // std::decay_t<Ts> is used to remove references/constness from the lambda
+    // types before they are passed as template arguments to the CombineVisitors
+    // struct.
+    return CombineVisitors<std::decay_t<Ts>...>{std::forward<Ts>(ts)...};
+}
+
+// This function takes ANY variant and ANY number of visitors, and performs the
+// visit. It is the reusable core logic.
+template <typename Variant, typename... Visitors>
+constexpr auto
+visit(Variant&& v, Visitors&&... visitors) -> decltype(auto)
+{
+    // Use the function template helper instead of raw CTAD.
+    auto visitor_set = make_combine_visitors(std::forward<Visitors>(visitors)...);
+
+    // Delegate to std::visit, perfectly forwarding the variant and the visitor
+    // set.
+    return std::visit(visitor_set, std::forward<Variant>(v));
+}
+
+}  // namespace detail
+
+}  // namespace xrpl

include/xrpl/protocol/ErrorCodes.h

@@ -153,7 +153,7 @@ enum warning_code_i {
     warnRPC_AMENDMENT_BLOCKED = 1002,
     warnRPC_EXPIRED_VALIDATOR_LIST = 1003,
     // unused = 1004
-    warnRPC_FIELDS_DEPRECATED = 2004,  // rippled needs to maintain
+    warnRPC_FIELDS_DEPRECATED = 2004,  // xrpld needs to maintain
                                        // compatibility with Clio on this code.
 };
 

include/xrpl/protocol/Feature.h

@@ -37,10 +37,10 @@
  * 5) If a supported feature (`Supported::yes`) was _ever_ in a released
  *     version, it can never be changed back to `Supported::no`, because
  *     it _may_ still become enabled at any time. This would cause newer
- *     versions of `rippled` to become amendment blocked.
+ *     versions of `xrpld` to become amendment blocked.
  *     Instead, to prevent newer versions from voting on the feature, use
  *     `VoteBehavior::Obsolete`. Obsolete features can not be voted for
- *     by any versions of `rippled` built with that setting, but will still
+ *     by any versions of `xrpld` built with that setting, but will still
  *     work correctly if they get enabled. If a feature remains obsolete
  *     for long enough that _all_ clients that could vote for it are
  *     amendment blocked, the feature can be removed from the code

include/xrpl/protocol/Fees.h

@@ -4,6 +4,10 @@
 
 namespace xrpl {
 
+// Deprecated constant for backwards compatibility with pre-XRPFees amendment.
+// This was the reference fee units used in the old fee calculation.
+inline constexpr std::uint32_t FEE_UNITS_DEPRECATED = 10;
+
 /** Reflects the fee settings for a particular ledger.
 
     The fees are always the same for any transactions applied
@@ -11,15 +15,25 @@ namespace xrpl {
 */
 struct Fees
 {
-    XRPAmount base{0};       // Reference tx cost (drops)
-    XRPAmount reserve{0};    // Reserve base (drops)
-    XRPAmount increment{0};  // Reserve increment (drops)
+    /** @brief Cost of a reference transaction in drops. */
+    XRPAmount base{0};
+
+    /** @brief Minimum XRP an account must hold to exist on the ledger. */
+    XRPAmount reserve{0};
+
+    /** @brief Additional XRP reserve required per owned ledger object. */
+    XRPAmount increment{0};
 
     explicit Fees() = default;
     Fees(Fees const&) = default;
     Fees&
     operator=(Fees const&) = default;
 
+    Fees(XRPAmount base_, XRPAmount reserve_, XRPAmount increment_)
+        : base(base_), reserve(reserve_), increment(increment_)
+    {
+    }
+
     /** Returns the account reserve given the owner count, in drops.
 
         The reserve is calculated as the reserve base plus

include/xrpl/protocol/IOUAmount.h

@@ -26,8 +26,8 @@ class IOUAmount : private boost::totally_ordered<IOUAmount>, private boost::addi
 private:
     using mantissa_type = std::int64_t;
     using exponent_type = int;
-    mantissa_type mantissa_;
-    exponent_type exponent_;
+    mantissa_type mantissa_{};
+    exponent_type exponent_{};
 
     /** Adjusts the mantissa and exponent to the proper range.
 

include/xrpl/protocol/Indexes.h

@@ -363,11 +363,12 @@ uint256
 getTicketIndex(AccountID const& account, SeqProxy ticketSeq);
 
 template <class... keyletParams>
+// NOLINTNEXTLINE(cppcoreguidelines-pro-type-member-init)
 struct keyletDesc
 {
     std::function<Keylet(keyletParams...)> function;
     Json::StaticString expectedLEName;
-    bool includeInTests;
+    bool includeInTests{};
 };
 
 // This list should include all of the keylet functions that take a single

include/xrpl/protocol/Issue.h

@@ -96,7 +96,7 @@ operator<=>(Issue const& lhs, Issue const& rhs)
 inline Issue const&
 xrpIssue()
 {
-    static Issue issue{xrpCurrency(), xrpAccount()};
+    static Issue const issue{xrpCurrency(), xrpAccount()};
     return issue;
 }
 
@@ -104,7 +104,7 @@ xrpIssue()
 inline Issue const&
 noIssue()
 {
-    static Issue issue{noCurrency(), noAccount()};
+    static Issue const issue{noCurrency(), noAccount()};
     return issue;
 }