diff --git a/src/core/game-client.ts b/src/core/game-client.ts
index 0c487c4..ba7e71c 100644
--- a/src/core/game-client.ts
+++ b/src/core/game-client.ts
@@ -1,35 +1,31 @@
-import { createPromptContext, PromptCall } from "@/utils/command";
-import { createMiddlewareChain } from "@/utils/middleware";
-import { computed } from "@preact/signals-core";
+import { createPromptContext, PromptDef } from "@/utils/command";
+import { computed, effect, signal } from "@preact/signals-core";
 import { createGameContext, IGameContext } from "./game";
 
-export interface GameClient<E extends {} = {}, T extends {} = {}> {
-  // c# calls this to generate a ReactiveProperty<T>
-  select<K extends keyof E>(
-    type: K,
-    id: string,
-    callback: (t: E[K]) => void,
-  ): () => void;
-
-  // c# calls this to interrupt and capture async events
-  use<K extends keyof T>(
-    trigger: K,
-    callback: (ctx: T[K], next: () => Promise<any>) => Promise<any>,
-  ): () => void;
-}
-
-export type EntityMap = {};
-
-export type ClientTriggerMap = {
-  status: { status: ClientStatus; result?: unknown };
-  prompt: PromptCall;
-};
-
 export enum ClientStatus {
   Idle = "idle",
   Running = "running",
   Disposed = "disposed",
 }
+
+export type PromptInfo =
+  | {
+      hasPrompt: false;
+      player: string;
+    }
+  | {
+      hasPrompt: true;
+      player: string;
+      def: PromptDef<unknown[]>;
+      tryAnswer(...args: unknown[]): string | null;
+    };
+
+/**
+ * 1. create a client instance
+ * 2. setStatus("running")
+ * 3. select("selector", t => {}) for c# to capture game state
+ * 4. useClient("status" | "prompt") for c# to handle prompt / game status
+ */
 export abstract class BaseGameClient<
   T extends Record<string, unknown> = Record<string, unknown>,
   R = unknown,
@@ -37,33 +33,32 @@ export abstract class BaseGameClient<
   protected _initialState: T;
   protected _context: IGameContext<T>;
   protected _prompts = createPromptContext();
-  protected _status = ClientStatus.Idle;
-
-  protected _setStatus = createMiddlewareChain(
-    async (ctx: ClientTriggerMap["status"]) => {
-      this._status = ctx.status;
-      if (this._status === ClientStatus.Disposed) {
-        this._prompts.reset();
-      } else if (this._status === ClientStatus.Running) {
-        this._prompts.reset();
-        this._context._state.value = this._initialState;
-        const r = await this.start(this._context);
-        this._setStatus.execute({ status: ClientStatus.Idle, result: r });
-      }
-    },
-  );
+  protected _status = signal(ClientStatus.Idle);
+  protected _result = signal(null as null | R);
+  public get state() {
+    return this._context.value;
+  }
   constructor(is: T) {
     this._initialState = is;
     this._context = createGameContext(this._prompts, is);
   }
 
-  setStatus(status: ClientStatus) {
-    this._setStatus.execute({ status });
+  async setStatus(status: ClientStatus) {
+    this._status.value = status;
+    if (status === ClientStatus.Disposed) {
+      this._prompts.reset();
+    } else if (status === ClientStatus.Running) {
+      this._prompts.reset();
+      this._context._state.value = this._initialState;
+      this._result.value = null;
+      this._result.value = await this.start(this._context);
+      this.setStatus(ClientStatus.Idle);
+    }
   }
 
   abstract start(ctx: IGameContext<T>): Promise<R>;
 
-  protected assignSelector<S>(selector: (t: T) => S, callback: (s: S) => void) {
+  assignSelector<S>(selector: (t: T) => S, callback: (s: S) => void) {
     const selected = computed(() => selector(this._context.value));
     return selected.subscribe(callback);
   }
@@ -77,27 +72,42 @@ export abstract class BaseGameClient<
     return resolve;
   }
 
-  useClient<K extends keyof ClientTriggerMap>(
-    trigger: K,
-    callback: (
-      ctx: ClientTriggerMap[K],
-      next: () => Promise<void>,
-    ) => Promise<void>,
-  ) {
-    if (trigger === "prompt") {
-      return this._prompts.handleCall.use(
-        callback as (
-          ctx: ClientTriggerMap["prompt"],
-          next: () => Promise<unknown>,
-        ) => Promise<void>,
-      );
-    } else if (trigger === "status") {
-      return this._setStatus.use(
-        callback as (
-          ctx: ClientTriggerMap["status"],
-          next: () => Promise<void>,
-        ) => Promise<void>,
-      );
-    }
+  selectPrompt(callback: (prompt: PromptInfo) => void) {
+    return this._prompts.handleCall.use(async (ctx, next) => {
+      function tryAnswer(...args: any[]) {
+        try {
+          const res = ctx.validator(...args);
+          ctx.resolve(res);
+          return null;
+        } catch (reason) {
+          if (typeof reason === "string") {
+            return reason;
+          }
+          throw reason;
+        }
+      }
+
+      callback({
+        hasPrompt: true,
+        player: ctx.player || "global",
+        def: ctx.def,
+        tryAnswer,
+      });
+      await next();
+      callback({
+        hasPrompt: false,
+        player: ctx.player || "global",
+      });
+    });
+  }
+  selectStatus(callback: (status: ClientStatus) => void) {
+    return effect(() => {
+      callback(this._status.value);
+    });
+  }
+  selectResult(callback: (status: R | null) => void) {
+    return effect(() => {
+      callback(this._result.value);
+    });
   }
 }
diff --git a/src/samples/tic-tac-toe.ts b/src/samples/tic-tac-toe.ts
index 2176cde..ba13d68 100644
--- a/src/samples/tic-tac-toe.ts
+++ b/src/samples/tic-tac-toe.ts
@@ -1,5 +1,5 @@
 import { Part } from "@/core/part";
-import { createRegion } from "@/core/region";
+import { createRegion, Region } from "@/core/region";
 import { createPromptDef, IGameContext } from "@/core/game";
 import { BaseGameClient, GameClient } from "@/core/game-client";
 import { createMiddlewareChain } from "@/utils/middleware";
@@ -186,7 +186,7 @@ export async function placePiece(
   });
 }
 
-type EntityMap = { parts: TicTacToePart };
+type EntityMap = { parts: TicTacToePart; board: Region };
 type TriggerMap = {
   turn: { player: PlayerType; turn: number };
 };