refactor: strengthen type modeling with discriminated unions

lib/types.ts

@@ -15,7 +15,7 @@ export interface Game {
   id: string
   name: string
   icon: string
-  category: string
+  category: "MOBA" | "FPS" | "动作" | "RPG"
 }
 
 export interface PlayerService {
@@ -26,7 +26,7 @@ export interface PlayerService {
   title: string
   description: string
   price: number
-  unit: string
+  unit: "局" | "星" | "次"
   rankRange?: string
   availability: string[]
 }
@@ -126,10 +126,8 @@ export interface Dispute {
   createdAt: string
 }
 
-export interface ChatSession {
+interface BaseChatSession {
   id: string
-  type: "consultation" | "order"
-  orderId?: string
   participants: { id: string; name: string; avatar: string }[]
   lastMessage?: string
   lastMessageAt?: string
@@ -137,6 +135,18 @@ export interface ChatSession {
   readonly: boolean
 }
 
+export interface OrderChatSession extends BaseChatSession {
+  type: "order"
+  orderId: string
+}
+
+export interface ConsultationChatSession extends BaseChatSession {
+  type: "consultation"
+  orderId?: never
+}
+
+export type ChatSession = OrderChatSession | ConsultationChatSession
+
 export interface ChatMessage {
   id: string
   sessionId: string