fix(agent): align DeepSeek Flash model references

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",
     );

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 }),
     });