fix(providers): preserve Volcengine custom destinations

Author: yrooogerg

src/providers/registry.ts

@@ -1107,6 +1107,7 @@ export const PROVIDER_REGISTRY: readonly ProviderRegistryEntry[] = [
     baseUrl: "https://ark.cn-beijing.volces.com/api/v3",
     adapter: "openai-chat",
     authKind: "key",
+    preserveCustomDestination: true,
     dashboardUrl: "https://console.volcengine.com/ark/region:ark+cn-beijing/apikey",
     defaultModel: "doubao-seed-2-1-pro-260628",
     models: VOLCENGINE_ARK_MODELS,
@@ -1139,6 +1140,7 @@ export const PROVIDER_REGISTRY: readonly ProviderRegistryEntry[] = [
     baseUrl: "https://ark.cn-beijing.volces.com/api/coding/v3",
     adapter: "openai-chat",
     authKind: "key",
+    preserveCustomDestination: true,
     dashboardUrl: "https://console.volcengine.com/ark/region:ark+cn-beijing/overview",
     defaultModel: "ark-code-latest",
     models: VOLCENGINE_CODING_PLAN_MODELS,
@@ -1160,6 +1162,7 @@ export const PROVIDER_REGISTRY: readonly ProviderRegistryEntry[] = [
     responsesPath: "/responses",
     adapter: "openai-responses",
     authKind: "key",
+    preserveCustomDestination: true,
     dashboardUrl: "https://console.volcengine.com/ark/region:ark+cn-beijing/overview",
     defaultModel: "deepseek-v4-pro",
     models: VOLCENGINE_AGENT_PLAN_MODELS,

tests/volcengine-providers.test.ts

@@ -21,6 +21,7 @@ describe("Volcengine Ark providers", () => {
       baseUrl: "https://ark.cn-beijing.volces.com/api/v3",
       adapter: "openai-chat",
       authKind: "key",
+      preserveCustomDestination: true,
       defaultModel: "doubao-seed-2-1-pro-260628",
       models: [
         "doubao-seed-2-1-pro-260628",
@@ -44,6 +45,7 @@ describe("Volcengine Ark providers", () => {
       baseUrl: "https://ark.cn-beijing.volces.com/api/coding/v3",
       adapter: "openai-chat",
       authKind: "key",
+      preserveCustomDestination: true,
       defaultModel: "ark-code-latest",
       models: [
         "ark-code-latest",
@@ -75,6 +77,7 @@ describe("Volcengine Ark providers", () => {
       responsesPath: "/responses",
       adapter: "openai-responses",
       authKind: "key",
+      preserveCustomDestination: true,
       defaultModel: "deepseek-v4-pro",
       models: [
         "deepseek-v4-pro",
@@ -144,6 +147,32 @@ describe("Volcengine Ark providers", () => {
     expect(request.url).toBe("https://ark.cn-beijing.volces.com/api/plan/v3/responses");
   });
 
+  test.each([
+    ["volcengine", "openai-chat", "https://custom.example.com/api/v3"],
+    ["volcengine-coding-plan", "openai-chat", "https://custom.example.com/api/coding/v3"],
+    ["volcengine-agent-plan", "openai-responses", "https://custom.example.com/api/plan/v3"],
+  ] as const)(
+    "preserves an existing same-name custom %s destination",
+    (providerId, adapter, baseUrl) => {
+      const config: OcxConfig = {
+        port: 10100,
+        defaultProvider: providerId,
+        providers: {
+          [providerId]: {
+            adapter,
+            baseUrl,
+            authMode: "key",
+            apiKey: "test-key",
+          },
+        },
+      };
+
+      const route = routeModel(config, `${providerId}/custom-model`);
+      expect(route.provider.baseUrl).toBe(baseUrl);
+      expect(route.provider.adapter).toBe(adapter);
+    },
+  );
+
   test("maps the documented Ark thinking toggle on the pay-as-you-go Chat wire", () => {
     const config: OcxConfig = {
       port: 10100,