From 5724cb7d97f3814cfd0ac560b6a6addcac4bad94 Mon Sep 17 00:00:00 2001
From: Poker Design Developer <developer@poker-design.local>
Date: Wed, 3 Jun 2026 22:26:48 +0800
Subject: [PATCH] feat: add DEFAULT_BACK_DESIGN and getEffectiveBackDesign

---
 frontend/src/utils/cardLayout.js   | 20 ++++++++++++++++++++
 frontend/src/utils/cardRenderer.js |  2 ++
 2 files changed, 22 insertions(+)

diff --git a/frontend/src/utils/cardLayout.js b/frontend/src/utils/cardLayout.js
index b7ec2bd..f0486b6 100644
--- a/frontend/src/utils/cardLayout.js
+++ b/frontend/src/utils/cardLayout.js
@@ -58,6 +58,15 @@ export function getEffectiveDesign(project, cardKey) {
   return { ...base, ...overrides }
 }
 
+/**
+ * 合并项目级 back_design 与背面 card_overrides
+ */
+export function getEffectiveBackDesign(project) {
+  const base = JSON.parse(JSON.stringify(project?.back_design || DEFAULT_BACK_DESIGN))
+  const overrides = (project?.card_overrides || {})['back'] || {}
+  return { ...base, ...overrides }
+}
+
 /**
  * 计算数字牌 (1-10) 实际的花色位置（绝对像素）
  *  - 默认按 LAYOUT_POSITIONS
@@ -136,3 +145,14 @@ export const DEFAULT_DESIGN = {
   font_color: '#000000',
   corner_offset: { x: 0, y: 0 },
 }
+
+export const DEFAULT_BACK_DESIGN = {
+  background_color: '#1A237E',
+  border_color: '#C0A050',
+  border_width: 3,
+  pattern_color: null,
+  image: null,
+  image_dx: 0,
+  image_dy: 0,
+  image_scale: 1,
+}
diff --git a/frontend/src/utils/cardRenderer.js b/frontend/src/utils/cardRenderer.js
index aac996c..61e146d 100644
--- a/frontend/src/utils/cardRenderer.js
+++ b/frontend/src/utils/cardRenderer.js
@@ -12,6 +12,8 @@ import {
   isJoker,
   computeNumberPipPositions,
   getEffectiveDesign,
+  getEffectiveBackDesign,
+  DEFAULT_BACK_DESIGN,
 } from './cardLayout.js'
 
 const CARD_W = 750