diff --git a/.opencode/agents/instruction.md b/.opencode/agents/instruction.md
index b4d4625..b6bf35d 100644
--- a/.opencode/agents/instruction.md
+++ b/.opencode/agents/instruction.md
@@ -1,7 +1,7 @@
 ---
 description: TJWater Agent，用于供水网络分析和操作员工作流
 mode: primary
-model: deepseek/deepseek-v4-flash
+model: deepseek/deepseek-flash
 ---
 你是 TJWater 供水管网分析 Agent，运用水力专业知识，回复用户时使用简体中文，内容要求简洁准确。
 
diff --git a/opencode.json b/opencode.json
index 83b9f89..5b8b025 100644
--- a/opencode.json
+++ b/opencode.json
@@ -7,7 +7,7 @@
       }
     }
   },
-  "model": "deepseek/deepseek-v4-flash",
+  "model": "deepseek/deepseek-flash",
   "server": {
     "hostname": "127.0.0.1",
     "port": 4096
diff --git a/src/chat/modelConfig.ts b/src/chat/modelConfig.ts
index e2797e9..74842f8 100644
--- a/src/chat/modelConfig.ts
+++ b/src/chat/modelConfig.ts
@@ -10,7 +10,7 @@ export type AgentModelOption = {
 
 export const defaultAgentModelOptions: AgentModelOption[] = [
   {
-    id: "deepseek/deepseek-v4-flash",
+    id: "deepseek/deepseek-flash",
     label: "快速",
     description: "快速回答和任务执行",
     icon: "bolt",
diff --git a/src/config.ts b/src/config.ts
index 80fc715..e54337a 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -52,7 +52,7 @@ const envSchema = z
     // opencode SDK 启动或连接运行时时的超时时间（毫秒）。
     OPENCODE_TIMEOUT_MS: z.coerce.number().int().positive().default(5000),
     // 默认使用的 opencode 模型标识。
-    OPENCODE_MODEL: z.string().default("deepseek/deepseek-v4-flash"),
+    OPENCODE_MODEL: z.string().default("deepseek/deepseek-flash"),
     // 聊天 UI 和 /stream 允许选择的 opencode 模型完整配置，JSON 数组。
     OPENCODE_MODEL_OPTIONS: z.string().default(defaultAgentModelOptionsJson),
     // opencode skills 树目录；会在运行时解析为绝对路径，避免工具 cwd 偏移。
diff --git a/src/learning/orchestrator.ts b/src/learning/orchestrator.ts
index 04ac637..a16396f 100644
--- a/src/learning/orchestrator.ts
+++ b/src/learning/orchestrator.ts
@@ -573,7 +573,7 @@ const toRuntimeModel = (model?: SupportedModel) => {
 };
 
 const GATE_MODEL = {
-  modelID: "deepseek-v4-flash",
+  modelID: "deepseek-flash",
   providerID: "deepseek",
 } as const;
 
diff --git a/tests/chat/models.test.ts b/tests/chat/models.test.ts
index 2580c2b..7079b68 100644
--- a/tests/chat/models.test.ts
+++ b/tests/chat/models.test.ts
@@ -6,7 +6,11 @@ import {
   resolveDefaultModel,
   supportedModels,
 } from "../../src/chat/models.js";
-import { parseAgentModelOptions } from "../../src/chat/modelConfig.js";
+import {
+  defaultAgentModelOptions,
+  getAgentModelIds,
+  parseAgentModelOptions,
+} from "../../src/chat/modelConfig.js";
 
 describe("agent model config", () => {
   it("keeps every exposed option in the supported model list", () => {
@@ -19,14 +23,19 @@ describe("agent model config", () => {
   });
 
   it("validates supported model ids", () => {
-    expect(isSupportedModel("deepseek/deepseek-v4-flash")).toBe(true);
+    expect(isSupportedModel(supportedModels[0])).toBe(true);
     expect(isSupportedModel("unknown/model")).toBe(false);
   });
 
-  it("rejects unsupported default models", () => {
-    expect(resolveDefaultModel("deepseek/deepseek-v4-pro")).toBe(
+  it("defaults to the currently selectable DeepSeek models", () => {
+    expect(getAgentModelIds(defaultAgentModelOptions)).toEqual([
+      "deepseek/deepseek-flash",
       "deepseek/deepseek-v4-pro",
-    );
+    ]);
+  });
+
+  it("rejects unsupported default models", () => {
+    expect(resolveDefaultModel(supportedModels[0])).toBe(supportedModels[0]);
     expect(() => resolveDefaultModel("unknown/model")).toThrow(
       "unsupported default agent model",
     );
diff --git a/tests/routes/chatStream.test.ts b/tests/routes/chatStream.test.ts
index e054876..40ad4d9 100644
--- a/tests/routes/chatStream.test.ts
+++ b/tests/routes/chatStream.test.ts
@@ -1087,7 +1087,7 @@ describe("streamPromptResponse", () => {
       sessionId: "runtime-session-1",
       clientSessionId: "client-session-1",
       message: "分析供水服务分区",
-      model: "deepseek/deepseek-v4-flash",
+      model: "deepseek/deepseek-flash",
       write: (event, data) => events.push({ event, data }),
     });