From cd9c3a79ab17dae4a924ad6e3bfac7c3ab11a773 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E5=88=98=E8=88=AA=E5=AE=87?= <3364451258@qq.com>
Date: Sun, 31 May 2026 13:38:04 +0800
Subject: [PATCH] =?UTF-8?q?fix:=20=E4=BF=AE=E5=A4=8D=E6=82=94=E6=A3=8B?=
 =?UTF-8?q?=E5=A5=87=E6=95=B0=E6=AD=A5=E5=B4=A9=E6=BA=83=E5=8F=8A=E7=A9=BA?=
 =?UTF-8?q?=E5=8E=86=E5=8F=B2=E9=94=99=E8=AF=AF=E8=AF=AD=E4=B9=89=20(NoHis?=
 =?UTF-8?q?tory)?=
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Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
---
 core/src/board.rs   | 11 ++++++++---
 core/src/types.rs   |  2 ++
 gui/src/commands.rs |  5 ++++-
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/core/src/board.rs b/core/src/board.rs
index 43f65ef..6c5c238 100644
--- a/core/src/board.rs
+++ b/core/src/board.rs
@@ -99,7 +99,7 @@ impl Board {
     /// 悔棋 — 撤销最近一步
     pub fn undo(&self) -> Result<Board, MoveError> {
         if self.history.is_empty() {
-            return Err(MoveError::GameOver);
+            return Err(MoveError::NoHistory);
         }
         let mut new_board = self.clone();
         let last_move = new_board.history.pop().unwrap();
@@ -253,9 +253,14 @@ mod tests {
     }
 
     #[test]
-    fn test_undo_empty_history() {
+    fn test_undo_empty_history_returns_no_history_error() {
         let board = Board::new(15);
-        assert_eq!(board.undo(), Err(MoveError::GameOver));
+        let result = board.undo();
+        assert!(result.is_err());
+        match result {
+            Err(MoveError::NoHistory) => {},
+            other => panic!("expected NoHistory, got {:?}", other),
+        }
     }
 
     #[test]
diff --git a/core/src/types.rs b/core/src/types.rs
index 564ef1f..714d04d 100644
--- a/core/src/types.rs
+++ b/core/src/types.rs
@@ -68,6 +68,7 @@ pub enum MoveError {
     Occupied,
     ForbiddenMove,
     GameOver,
+    NoHistory,
 }
 
 impl std::fmt::Display for MoveError {
@@ -77,6 +78,7 @@ impl std::fmt::Display for MoveError {
             MoveError::Occupied => "该位置已有棋子",
             MoveError::ForbiddenMove => "禁手位置，不能落子",
             MoveError::GameOver => "游戏已结束",
+            MoveError::NoHistory => "没有可撤销的棋子",
         };
         write!(f, "{}", msg)
     }
diff --git a/gui/src/commands.rs b/gui/src/commands.rs
index 948f77f..df64fce 100644
--- a/gui/src/commands.rs
+++ b/gui/src/commands.rs
@@ -94,7 +94,10 @@ pub fn undo(steps: u32, state: State<AppState>) -> Result<(), String> {
     let mut board_opt = state.board.lock().map_err(|e| e.to_string())?;
     let mut board = board_opt.clone().ok_or("游戏未开始")?;
 
-    for _ in 0..steps * 2 {
+    let max_undo = board.history().len() as u32;
+    let actual_steps = (steps * 2).min(max_undo);
+
+    for _ in 0..actual_steps {
         board = board.undo().map_err(|e| e.to_string())?;
     }