feat: 发起时指派——assignPolicy 配置/assign_json 快照/引擎收窄/preview+apply 契约

src/main/java/com/yunhai/flowcenter/engine/FlowDefModel.java

@@ -46,6 +46,10 @@ public class FlowDefModel {
     public static final String ASSIGNEE_DEPT_KEY = "DEPT_KEY";
     public static final String ASSIGNEE_USERS = "USERS";
 
+    /** 发起时指派选择模式：SINGLE=恰 1 人；MULTI=多选（min~max） */
+    public static final String ASSIGN_MODE_SINGLE = "SINGLE";
+    public static final String ASSIGN_MODE_MULTI = "MULTI";
+
     public String code;
     public String name;
     public String start;
@@ -81,6 +85,8 @@ public class FlowDefModel {
         public String waitFor;
         /** 办理时限小时数（自然时间，任务 arrive_time + N 小时；可空） */
         public Integer deadlineHours;
+        /** 发起时指派策略（2026-10-13 方案）：存在即允许指派；缺省/缺失=不允许（向前兼容） */
+        public AssignPolicy assignPolicy;
     }
 
     @JsonIgnoreProperties(ignoreUnknown = true)
@@ -91,6 +97,16 @@ public class FlowDefModel {
         public List<Integer> userIds;
     }
 
+    /** 发起时指派策略：mode 必填（容错 null=MULTI）；min/max 可空（缺省 1/候选全量数）；required 仅子应用 UI 用 */
+    @JsonIgnoreProperties(ignoreUnknown = true)
+    public static class AssignPolicy {
+        /** SINGLE | MULTI */
+        public String mode;
+        public Integer min;
+        public Integer max;
+        public Boolean required;
+    }
+
     @JsonIgnoreProperties(ignoreUnknown = true)
     public static class Edge {
         public String from;