From cf03c4cb8f5c8c4944b82d90640a49fbe9c5b255 Mon Sep 17 00:00:00 2001
From: tequ <git@tequ.dev>
Date: Wed, 7 Jan 2026 12:31:01 +0900
Subject: [PATCH] change Sponsor related fields to `soeDEFAULT`

---
 .../xrpl/protocol/detail/ledger_entries.macro | 10 ++++-----
 src/libxrpl/ledger/View.cpp                   |  5 ++++-
 src/test/app/Sponsor_test.cpp                 | 21 ++++++++++++++++++-
 src/xrpld/app/tx/detail/SponsorshipSet.cpp    |  4 ----
 src/xrpld/app/tx/detail/Transactor.cpp        | 10 +++++++--
 5 files changed, 37 insertions(+), 13 deletions(-)

diff --git a/include/xrpl/protocol/detail/ledger_entries.macro b/include/xrpl/protocol/detail/ledger_entries.macro
index 75b9aa49e3..20cff0e41b 100644
--- a/include/xrpl/protocol/detail/ledger_entries.macro
+++ b/include/xrpl/protocol/detail/ledger_entries.macro
@@ -150,9 +150,9 @@ LEDGER_ENTRY(ltACCOUNT_ROOT, 0x0061, AccountRoot, account, ({
     {sfAMMID,                soeOPTIONAL}, // pseudo-account designator
     {sfVaultID,              soeOPTIONAL}, // pseudo-account designator
     {sfLoanBrokerID,         soeOPTIONAL}, // pseudo-account designator
-    {sfSponsoredOwnerCount,  soeOPTIONAL},
-    {sfSponsoringOwnerCount, soeOPTIONAL},
-    {sfSponsoringAccountCount,soeOPTIONAL},
+    {sfSponsoredOwnerCount,  soeDEFAULT},
+    {sfSponsoringOwnerCount, soeDEFAULT},
+    {sfSponsoringAccountCount,soeDEFAULT},
 }))
 
 /** A ledger object which contains a list of object identifiers.
@@ -616,9 +616,9 @@ LEDGER_ENTRY(ltSPONSORSHIP, 0x0090, Sponsorship, sponsorship, ({
     {sfPreviousTxnLgrSeq,    soeREQUIRED},
     {sfOwner,                soeREQUIRED},
     {sfSponsee,              soeREQUIRED},
-    {sfFeeAmount,            soeOPTIONAL},
+    {sfFeeAmount,            soeDEFAULT},
     {sfMaxFee,               soeOPTIONAL},
-    {sfReserveCount,         soeOPTIONAL},
+    {sfReserveCount,         soeDEFAULT},
     {sfOwnerNode,            soeREQUIRED},
     {sfSponseeNode,          soeREQUIRED},
 }))
diff --git a/src/libxrpl/ledger/View.cpp b/src/libxrpl/ledger/View.cpp
index 802aeb9a4b..e4238b199b 100644
--- a/src/libxrpl/ledger/View.cpp
+++ b/src/libxrpl/ledger/View.cpp
@@ -1387,7 +1387,10 @@ adjustOwnerCount(
                 currentReserveCount >= amount,
                 "xrpl::adjustOwnerCount : enough reserve count");
 
-            sle->setFieldU32(sfReserveCount, currentReserveCount - amount);
+            if (currentReserveCount - amount > 0)
+                sle->setFieldU32(sfReserveCount, currentReserveCount - amount);
+            else
+                sle->makeFieldAbsent(sfReserveCount);
             view.update(sle);
         }
     }
diff --git a/src/test/app/Sponsor_test.cpp b/src/test/app/Sponsor_test.cpp
index 6c642af5cd..45c8f30d19 100644
--- a/src/test/app/Sponsor_test.cpp
+++ b/src/test/app/Sponsor_test.cpp
@@ -990,7 +990,7 @@ public:
                     auto sponsorFee = sponsorFeeBalance(sponsor, alice);
 
                     env(pay(alice, bob, XRP(100)),
-                        fee(XRP(100) + drops(1)),
+                        fee(XRP(90) + drops(1)),
                         sponsor::as(sponsor, tfSponsorFee),
                         ter(terINSUF_FEE_B));
                     env.close();
@@ -1001,6 +1001,25 @@ public:
                     BEAST_EXPECT(
                         sponsorFeeBalance(sponsor, alice) == sponsorFee);
                 }
+                // use all FeeAmount
+                {
+                    // = FeeAmount
+                    auto aliceBalance = env.balance(alice);
+                    auto bobBalance = env.balance(bob);
+                    auto sponsorBalance = env.balance(sponsor);
+
+                    env(pay(alice, bob, XRP(100)),
+                        fee(XRP(90)),
+                        sponsor::as(sponsor, tfSponsorFee),
+                        ter(tesSUCCESS));
+                    env.close();
+
+                    BEAST_EXPECT(env.balance(alice) == aliceBalance - XRP(100));
+                    BEAST_EXPECT(env.balance(bob) == bobBalance + XRP(100));
+                    BEAST_EXPECT(env.balance(sponsor) == sponsorBalance);
+                    BEAST_EXPECT(!env.le(keylet::sponsor(sponsor, alice))
+                                      ->isFieldPresent(sfFeeAmount));
+                }
 
                 // reset FeeAmount and MaxFee
                 env(sponsor::del(sponsor), sponsor::sponseeAcc(alice));
diff --git a/src/xrpld/app/tx/detail/SponsorshipSet.cpp b/src/xrpld/app/tx/detail/SponsorshipSet.cpp
index cdb84292ac..8f61f86b44 100644
--- a/src/xrpld/app/tx/detail/SponsorshipSet.cpp
+++ b/src/xrpld/app/tx/detail/SponsorshipSet.cpp
@@ -271,13 +271,9 @@ SponsorshipSet::doApply()
             (*newSle)[sfFeeAmount] = *feeAmount;
         }
         if (maxFee)
-        {
             (*newSle)[sfMaxFee] = *maxFee;
-        }
         if (reserveCount)
-        {
             (*newSle)[sfReserveCount] = *reserveCount;
-        }
 
         auto flags = 0;
         if (ctx_.tx.isFlag(tfSponsorshipSetRequireSignForFee))
diff --git a/src/xrpld/app/tx/detail/Transactor.cpp b/src/xrpld/app/tx/detail/Transactor.cpp
index 0398c15284..34c6c48fab 100644
--- a/src/xrpld/app/tx/detail/Transactor.cpp
+++ b/src/xrpld/app/tx/detail/Transactor.cpp
@@ -501,8 +501,14 @@ Transactor::payFee()
     if (!sle)
         return tefINTERNAL;  // LCOV_EXCL_LINE
 
-    sle->setFieldAmount(
-        result.field, sle->getFieldAmount(result.field) - feePaid);
+    auto const feeAmountAfter = sle->getFieldAmount(result.field) - feePaid;
+
+    if (feeAmountAfter == beast::zero &&
+        result.field.fieldMeta == SField::sMD_Default)
+        // for ltSponsorship.sfFeeAmount
+        sle->makeFieldAbsent(result.field);
+    else
+        sle->setFieldAmount(result.field, feeAmountAfter);
 
     view().update(sle);