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index 3a0805a..c12a520 100644
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diff --git a/card_game/__pycache__/battlefield.cpython-312.pyc b/card_game/__pycache__/battlefield.cpython-312.pyc
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diff --git a/card_game/__pycache__/player.cpython-312.pyc b/card_game/__pycache__/player.cpython-312.pyc
index 2a4d497..0e209a4 100644
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diff --git a/card_game/__pycache__/ui.cpython-312.pyc b/card_game/__pycache__/ui.cpython-312.pyc
index f4a5550..d17317d 100644
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diff --git a/card_game/ai.py b/card_game/ai.py
index 68f6c24..3ed5be2 100644
--- a/card_game/ai.py
+++ b/card_game/ai.py
@@ -85,7 +85,7 @@ class AIPlayer:
 
         # Frontline units: attack enemy frontline > enemy support > capital
         for unit in ai.get_frontline_units():
-            if not unit.can_attack or unit.has_attacked:
+            if not unit.can_attack or unit.has_attacked or not ai.can_afford_attack(unit):
                 continue
             enemy_front = player.get_frontline_units()
             enemy_support = player.get_support_units()
@@ -104,7 +104,7 @@ class AIPlayer:
 
         # Support units: attack enemy frontline > enemy support > capital (ranged only)
         for unit in ai.get_support_units():
-            if not unit.can_attack or unit.has_attacked:
+            if not unit.can_attack or unit.has_attacked or not ai.can_afford_attack(unit):
                 continue
             enemy_front = player.get_frontline_units()
             enemy_support = player.get_support_units()
diff --git a/card_game/battlefield.py b/card_game/battlefield.py
index 18ebd8f..1823de7 100644
--- a/card_game/battlefield.py
+++ b/card_game/battlefield.py
@@ -79,12 +79,17 @@ class Battlefield:
 
     def resolve_attack(self, attacker, defender):
         dead = []
+        owner = self._get_unit_owner(attacker)
+        if owner:
+            attack_cost = owner.get_attack_cost(attacker)
+            if owner.provisions < attack_cost:
+                return dead
+            owner.provisions -= attack_cost
         atk = attacker.get_effective_attack()
 
         if "siege" in attacker.abilities and defender == "capital":
             atk *= 2
 
-        owner = self._get_unit_owner(attacker)
         if (owner and owner.faction_id == "han"
                 and attacker.unit_type == "archer" and defender == "capital"):
             atk += 1
diff --git a/card_game/config.py b/card_game/config.py
index 7d3e3ba..ea6e19d 100644
--- a/card_game/config.py
+++ b/card_game/config.py
@@ -95,9 +95,10 @@ MAX_HAND_SIZE = 8
 
 # --- Game Rules ---
 STARTING_CAPITAL_HP = 20
-MAX_PROVISIONS = 10
+MAX_PROVISIONS = 12
 DECK_SIZE = 30
-STARTING_HAND_SIZE = 4
+FIRST_HAND_SIZE = 4
+SECOND_HAND_SIZE = 5
 FATIGUE_START_DAMAGE = 1
 
 # --- Rarity ---
diff --git a/card_game/main.py b/card_game/main.py
index 95a125f..63a4700 100644
--- a/card_game/main.py
+++ b/card_game/main.py
@@ -33,6 +33,7 @@ class Game:
         self.player_faction = None
         self.ai_faction = None
         self.custom_deck = None
+        self.player_goes_first = True
         self._load_custom_deck()
         self.custom_deck = None
 
@@ -112,6 +113,16 @@ class Game:
             self.player_faction = fid
             self.custom_deck = None
             self._load_custom_deck()
+            self.state = "turn_order"
+
+    # --- State: Turn Order ---
+
+    def _handle_click_turn_order(self, pos):
+        if "first" in self.ui.menu_buttons and self.ui.menu_buttons["first"].collidepoint(pos):
+            self.player_goes_first = True
+            self.state = "deck_select"
+        elif "second" in self.ui.menu_buttons and self.ui.menu_buttons["second"].collidepoint(pos):
+            self.player_goes_first = False
             self.state = "deck_select"
 
     # --- State: Deck Select ---
@@ -184,16 +195,30 @@ class Game:
             self.ui.deck_builder_cards.remove(cid)
 
     def _start_game(self):
+        from card_game.config import FIRST_HAND_SIZE, SECOND_HAND_SIZE
         self.battlefield = Battlefield(self.player_faction, self.ai_faction)
+        if self.player_goes_first:
+            self.battlefield.player.start_game(FIRST_HAND_SIZE)
+            self.battlefield.ai.start_game(SECOND_HAND_SIZE)
+        else:
+            self.battlefield.player.start_game(SECOND_HAND_SIZE)
+            self.battlefield.ai.start_game(FIRST_HAND_SIZE)
         if self.custom_deck:
             self.battlefield.player.deck.build(self.custom_deck)
+            hand_size = FIRST_HAND_SIZE if self.player_goes_first else SECOND_HAND_SIZE
             self.battlefield.player.hand = []
-            for _ in range(4):
+            for _ in range(hand_size):
                 self.battlefield.player.draw_card()
-        self.battlefield.start_game()
+        self.battlefield.turn_number = 1
+        self.battlefield.frontline_controller = None
+        self.battlefield.current_turn = "player"
+        self.battlefield.player.start_turn(1)
         self.ai_player = AIPlayer(self.battlefield)
         self.ui.clear_selection()
-        self.state = "playing"
+        if self.player_goes_first:
+            self.state = "playing"
+        else:
+            self._start_ai_turn()
 
     # --- State: Playing ---
 
@@ -267,7 +292,7 @@ class Game:
         opponent = self.battlefield.get_opponent(player)
 
         if unit.zone == "support":
-            if unit.can_attack and not unit.has_attacked:
+            if unit.can_attack and not unit.has_attacked and player.can_afford_attack(unit):
                 self.ui.selected_unit = unit
                 self.ui.target_mode = "attack"
                 targets = list(opponent.get_frontline_units())
@@ -282,7 +307,7 @@ class Game:
                     self.ui.selected_unit = unit
                     self.ui.target_mode = "move"
         elif unit.zone == "frontline":
-            if unit.can_attack and not unit.has_attacked:
+            if unit.can_attack and not unit.has_attacked and player.can_afford_attack(unit):
                 self.ui.selected_unit = unit
                 self.ui.target_mode = "attack"
                 targets = list(opponent.get_frontline_units())
@@ -417,8 +442,7 @@ class Game:
                 y = zone_y + ZONE_HEIGHT // 2
             else:
                 x = _frontline_slot_x(unit.slot, n_fl) + FIELD_CARD_WIDTH // 2
-                zone_y = FRONTLINE_Y if is_ai else (FRONTLINE_Y + half)
-                y = zone_y + half // 2
+                y = FRONTLINE_Y + ZONE_HEIGHT // 2
             return x, y
 
         try:
@@ -518,6 +542,8 @@ class Game:
     def _handle_click(self, pos):
         if self.state == "menu":
             self._handle_click_menu(pos)
+        elif self.state == "turn_order":
+            self._handle_click_turn_order(pos)
         elif self.state == "deck_select":
             self._handle_click_deck_select(pos)
         elif self.state == "deck_build":
@@ -537,6 +563,8 @@ class Game:
     def _draw(self):
         if self.state == "menu":
             self.ui.draw_menu()
+        elif self.state == "turn_order":
+            self.ui.draw_turn_order(self.player_faction)
         elif self.state == "deck_select":
             self.ui.draw_deck_select(self.player_faction)
         elif self.state == "deck_build":
diff --git a/card_game/player.py b/card_game/player.py
index 4547a59..894cf86 100644
--- a/card_game/player.py
+++ b/card_game/player.py
@@ -2,8 +2,9 @@
 
 from card_game.config import (
     STARTING_CAPITAL_HP, MAX_PROVISIONS, MAX_HAND_SIZE,
-    MAX_SUPPORT_SLOTS, MAX_FRONTLINE_SLOTS, DECK_SIZE, STARTING_HAND_SIZE,
+    MAX_SUPPORT_SLOTS, MAX_FRONTLINE_SLOTS, DECK_SIZE,
     FATIGUE_START_DAMAGE, FACTIONS, DECK_PRESETS,
+    FIRST_HAND_SIZE, SECOND_HAND_SIZE,
 )
 from card_game.deck import Deck
 from card_game.card import Card
@@ -33,14 +34,16 @@ class Player:
         preset = DECK_PRESETS[self.faction_id]
         self.deck.build(preset["cards"])
 
-    def start_game(self):
+    def start_game(self, hand_size=None):
         self.build_deck()
-        for _ in range(STARTING_HAND_SIZE):
+        if hand_size is None:
+            hand_size = FIRST_HAND_SIZE
+        for _ in range(hand_size):
             self.draw_card()
 
     def start_turn(self, turn_number):
         self.turn_number = turn_number
-        gained = min(turn_number + 1, MAX_PROVISIONS)
+        gained = min(turn_number, MAX_PROVISIONS)
         self.provisions = gained
         self.max_provisions = gained
 
@@ -176,6 +179,15 @@ class Player:
                 if unit.current_hp < unit.max_hp:
                     unit.current_hp = min(unit.max_hp, unit.current_hp + 1)
 
+    def get_attack_cost(self, unit):
+        cost = unit.op_cost
+        if self.faction_id == "yan" and unit.unit_type == "cavalry":
+            cost = max(0, cost - 1)
+        return cost
+
+    def can_afford_attack(self, unit):
+        return self.provisions >= self.get_attack_cost(unit)
+
     def cleanup_dead(self):
         for i in range(len(self.support_line)):
             u = self.support_line[i]
diff --git a/card_game/ui.py b/card_game/ui.py
index 410a0d7..31fd6fb 100644
--- a/card_game/ui.py
+++ b/card_game/ui.py
@@ -131,6 +131,30 @@ class UI:
         inst = self.font_sm.render("选择你的国家开始游戏", True, INK_WASH_3)
         self.screen.blit(inst, (WINDOW_WIDTH // 2 - inst.get_width() // 2, WINDOW_HEIGHT - 60))
 
+    def draw_turn_order(self, player_faction):
+        ink_style.blit_paper_background(self.screen)
+        ink_style.blit_mountains(self.screen)
+        faction = FACTIONS[player_faction]
+        title = self.font_xl.render("选择先后手", True, FACTION_COLORS[player_faction])
+        self.screen.blit(title, (WINDOW_WIDTH // 2 - title.get_width() // 2, 100))
+        faction_text = self.font_lg.render(f"你的国家：{faction['name']}", True, PAPER_WHITE)
+        self.screen.blit(faction_text, (WINDOW_WIDTH // 2 - faction_text.get_width() // 2, 180))
+
+        self.menu_buttons = {}
+        for key, lbl, desc, y in [
+            ("first", "先手", "先行动，起始4张手牌", 280),
+            ("second", "后手", "后行动，起始5张手牌", 370),
+        ]:
+            btn_w, btn_h = 300, 70
+            rect = pygame.Rect(WINDOW_WIDTH // 2 - btn_w // 2, y, btn_w, btn_h)
+            ink_style.draw_ink_rect(self.screen, rect, FACTION_COLORS[player_faction], alpha=200)
+            pygame.draw.rect(self.screen, PAPER_WHITE, rect, 2, border_radius=5)
+            t = self.font_lg.render(lbl, True, PAPER_WHITE)
+            self.screen.blit(t, (rect.centerx - t.get_width() // 2, y + 10))
+            d = self.font_sm.render(desc, True, LIGHT_GRAY)
+            self.screen.blit(d, (rect.centerx - d.get_width() // 2, y + 45))
+            self.menu_buttons[key] = rect
+
     def draw_deck_select(self, player_faction):
         ink_style.blit_paper_background(self.screen)
         ink_style.blit_mountains(self.screen)
@@ -423,27 +447,23 @@ class UI:
 
     def _draw_frontline(self, battlefield):
         y = FRONTLINE_Y
-        half = ZONE_HEIGHT // 2
-
-        # Center divider line
-        pygame.draw.line(self.screen, INK_WASH_3, (0, y + half), (WINDOW_WIDTH, y + half), 1)
 
         lbl = self.font_sm.render("前 线", True, (ZHU_HONG[0], ZHU_HONG[1], ZHU_HONG[2]))
         self.screen.blit(lbl, (WINDOW_WIDTH // 2 - lbl.get_width() // 2, y + 3))
 
         n_fl = MAX_FRONTLINE_SLOTS
+        uy = y + (ZONE_HEIGHT - FIELD_CARD_HEIGHT) // 2
+
         for i, unit in enumerate(battlefield.ai.frontline):
             if unit is None:
                 continue
             ux = _frontline_slot_x(i, n_fl)
-            uy = y + (half - FIELD_CARD_HEIGHT) // 2
             self._draw_field_unit(unit, ux, uy, False, battlefield.ai)
 
         for i, unit in enumerate(battlefield.player.frontline):
             if unit is None:
                 continue
             ux = _frontline_slot_x(i, n_fl)
-            uy = y + half + (half - FIELD_CARD_HEIGHT) // 2
             self._draw_field_unit(unit, ux, uy, True, battlefield.player)
 
     def _draw_capital(self, player, zone_y):
@@ -659,10 +679,9 @@ class UI:
                     ux = _support_slot_x(unit.slot)
                     uy = zone_y + (zone_h - FIELD_CARD_HEIGHT) // 2
                 else:
-                    half = ZONE_HEIGHT // 2
                     n_fl = MAX_FRONTLINE_SLOTS
-                    zone_y = FRONTLINE_Y if is_ai else (FRONTLINE_Y + half)
-                    zone_h = half
+                    zone_y = FRONTLINE_Y
+                    zone_h = ZONE_HEIGHT
                     ux = _frontline_slot_x(unit.slot, n_fl)
                     uy = zone_y + (zone_h - FIELD_CARD_HEIGHT) // 2
                 s = pygame.Surface((FIELD_CARD_WIDTH, FIELD_CARD_HEIGHT), pygame.SRCALPHA)
@@ -681,12 +700,11 @@ class UI:
 
         # Move highlights
         if self.target_mode == "move":
-            half = ZONE_HEIGHT // 2
             n_fl = MAX_FRONTLINE_SLOTS
             for i, slot in enumerate(battlefield.player.frontline):
                 if slot is None:
                     sx = _frontline_slot_x(i, n_fl)
-                    sy = FRONTLINE_Y + half + (half - FIELD_CARD_HEIGHT) // 2
+                    sy = FRONTLINE_Y + (ZONE_HEIGHT - FIELD_CARD_HEIGHT) // 2
                     s = pygame.Surface((FIELD_CARD_WIDTH, FIELD_CARD_HEIGHT), pygame.SRCALPHA)
                     s.fill((100, 180, 220, 50))
                     self.screen.blit(s, (sx, sy))
@@ -717,7 +735,7 @@ class UI:
         n_fl = MAX_FRONTLINE_SLOTS
         zones = [
             (battlefield.player.support_line, PLAYER_SUPPORT_Y, ZONE_HEIGHT, battlefield.player, "support"),
-            (battlefield.player.frontline, FRONTLINE_Y + half, half, battlefield.player, "frontline"),
+            (battlefield.player.frontline, FRONTLINE_Y, ZONE_HEIGHT, battlefield.player, "frontline"),
             (battlefield.ai.support_line, ENEMY_SUPPORT_Y, ZONE_HEIGHT, battlefield.ai, "support"),
             (battlefield.ai.frontline, FRONTLINE_Y, half, battlefield.ai, "frontline"),
         ]
@@ -750,12 +768,11 @@ class UI:
 
     def get_frontline_slot_at(self, pos, player):
         mx, my = pos
-        half = ZONE_HEIGHT // 2
         n_fl = MAX_FRONTLINE_SLOTS
-        zone_y = FRONTLINE_Y + half
+        zone_y = FRONTLINE_Y
         for i, slot in enumerate(player.frontline):
             sx = _frontline_slot_x(i, n_fl)
-            sy = zone_y + (half - FIELD_CARD_HEIGHT) // 2
+            sy = zone_y + (ZONE_HEIGHT - FIELD_CARD_HEIGHT) // 2
             rect = pygame.Rect(sx, sy, FIELD_CARD_WIDTH, FIELD_CARD_HEIGHT)
             if rect.collidepoint(mx, my):
                 return i