From e8ff9ed909d5b3853660c1e1f26140e7df0fc598 Mon Sep 17 00:00:00 2001
From: winapiadmin <138602885+winapiadmin@users.noreply.github.com>
Date: Sun, 29 Mar 2026 23:37:14 +0700
Subject: [PATCH 1/5] Update doNullMove to handle en passant state

---
 position.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/position.h b/position.h
index 932b795..77a6761 100644
--- a/position.h
+++ b/position.h
@@ -182,6 +182,9 @@ template <typename PieceC = EnginePiece, typename = std::enable_if_t<is_piece_en
 
     inline void doNullMove() {
         history.push_back(current_state);
+        if (current_state.epIncluded) current_state.hash ^= zobrist::RandomEP[file_of(ep_square())];
+        current_state.epIncluded=false;
+        current_state.enPassant=SQ_NONE;
         current_state.turn = ~current_state.turn;
         current_state.hash ^= zobrist::RandomTurn;
         current_state.fullMoveNumber += (current_state.turn == WHITE);

From 73eb819134670a91d6360ca4f8166c321ebf14d8 Mon Sep 17 00:00:00 2001
From: GitHub Actions <actions@github.com>
Date: Sun, 29 Mar 2026 16:37:37 +0000
Subject: [PATCH 2/5] Apply clang-format

---
 position.h | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/position.h b/position.h
index 77a6761..8d3bc85 100644
--- a/position.h
+++ b/position.h
@@ -182,9 +182,10 @@ template <typename PieceC = EnginePiece, typename = std::enable_if_t<is_piece_en
 
     inline void doNullMove() {
         history.push_back(current_state);
-        if (current_state.epIncluded) current_state.hash ^= zobrist::RandomEP[file_of(ep_square())];
-        current_state.epIncluded=false;
-        current_state.enPassant=SQ_NONE;
+        if (current_state.epIncluded)
+            current_state.hash ^= zobrist::RandomEP[file_of(ep_square())];
+        current_state.epIncluded = false;
+        current_state.enPassant = SQ_NONE;
         current_state.turn = ~current_state.turn;
         current_state.hash ^= zobrist::RandomTurn;
         current_state.fullMoveNumber += (current_state.turn == WHITE);

From b457d385f942858bb197de5eaae4ede5b3604576 Mon Sep 17 00:00:00 2001
From: winapiadmin <138602885+winapiadmin@users.noreply.github.com>
Date: Sun, 29 Mar 2026 23:37:57 +0700
Subject: [PATCH 3/5] Add tests for move, null move, and undo move

---
 tests.cpp | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/tests.cpp b/tests.cpp
index 3c60bf0..22acd44 100644
--- a/tests.cpp
+++ b/tests.cpp
@@ -402,6 +402,17 @@ TEST_CASE("Experienced bugs in this repo") {
         REQUIRE(p.zobrist() == p.hash());
         REQUIRE(p.hash() == 4177524090105507023);
     }
+    {
+        Position p;
+        p.doMove<false>(Move(SQ_F7, SQ_F5));
+        REQUIRE(p.zobrist() == p.hash());
+        p.doNullMove();
+        REQUIRE(p.zobrist() == p.hash());
+        p.undoMove();
+        REQUIRE(p.zobrist() == p.hash());
+        p.undoMove();
+        REQUIRE(p.zobrist() == p.hash());
+    }
     {
         Position p;
         REQUIRE(p.getCastlingPath(WHITE, true) == 0x60);

From b7545062d313ce4ffd4c4f24fbc53a644941ed58 Mon Sep 17 00:00:00 2001
From: winapiadmin <138602885+winapiadmin@users.noreply.github.com>
Date: Sun, 29 Mar 2026 23:42:50 +0700
Subject: [PATCH 4/5] Update tests.cpp

---
 tests.cpp | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/tests.cpp b/tests.cpp
index 22acd44..ee557da 100644
--- a/tests.cpp
+++ b/tests.cpp
@@ -404,6 +404,12 @@ TEST_CASE("Experienced bugs in this repo") {
     }
     {
         Position p;
+        p.doMove<false>(Move(SQ_A2, SQ_A3));
+        REQUIRE(p.zobrist() == p.hash());
+        p.doMove<false>(Move(SQ_B8, SQ_A6));
+        REQUIRE(p.zobrist() == p.hash());
+        p.doMove<false>(Move(SQ_F2, SQ_F3));
+        REQUIRE(p.zobrist() == p.hash());
         p.doMove<false>(Move(SQ_F7, SQ_F5));
         REQUIRE(p.zobrist() == p.hash());
         p.doNullMove();
@@ -412,6 +418,12 @@ TEST_CASE("Experienced bugs in this repo") {
         REQUIRE(p.zobrist() == p.hash());
         p.undoMove();
         REQUIRE(p.zobrist() == p.hash());
+        p.undoMove();
+        REQUIRE(p.zobrist() == p.hash());
+        p.undoMove();
+        REQUIRE(p.zobrist() == p.hash());
+        p.undoMove();
+        REQUIRE(p.zobrist() == p.hash());
     }
     {
         Position p;

From 0e69ea84d8d0d5ecec0cd7828d544197a60aa074 Mon Sep 17 00:00:00 2001
From: winapiadmin <138602885+winapiadmin@users.noreply.github.com>
Date: Sun, 29 Mar 2026 16:54:13 +0000
Subject: [PATCH 5/5] fix 1

---
 position.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/position.h b/position.h
index 8d3bc85..3f6e036 100644
--- a/position.h
+++ b/position.h
@@ -182,6 +182,9 @@ template <typename PieceC = EnginePiece, typename = std::enable_if_t<is_piece_en
 
     inline void doNullMove() {
         history.push_back(current_state);
+        current_state.incr_sqs[0] = current_state.incr_sqs[1] = current_state.incr_sqs[2] = current_state.incr_sqs[3] = SQ_NONE;
+        current_state.incr_pc[0] = current_state.incr_pc[1] = current_state.incr_pc[2] = current_state.incr_pc[3] =
+            PieceC::NO_PIECE;
         if (current_state.epIncluded)
             current_state.hash ^= zobrist::RandomEP[file_of(ep_square())];
         current_state.epIncluded = false;