diff --git a/.changeset/google-vertex-service-account.md b/.changeset/google-vertex-service-account.md
new file mode 100644
index 0000000000..9ebb2f1ac7
--- /dev/null
+++ b/.changeset/google-vertex-service-account.md
@@ -0,0 +1,8 @@
+---
+"@moonshot-ai/acp-adapter": patch
+"@moonshot-ai/agent-core": patch
+"@moonshot-ai/agent-core-v2": patch
+"@moonshot-ai/kosong": patch
+---
+
+feat: add GCP service account file support for google-vertex and google-vertex-anthropic
diff --git a/docs/en/configuration/providers.md b/docs/en/configuration/providers.md
index 43aeabb442..e8cf9ea3e3 100644
--- a/docs/en/configuration/providers.md
+++ b/docs/en/configuration/providers.md
@@ -130,27 +130,33 @@ api_key = "xxxxx"
 base_url = "https://your-gateway.example"
 ```
 
-## `vertexai`
+## `google-vertex` / `vertexai`
 
-Shares the same implementation as `google-genai`; setting `type = "vertexai"` switches to the Vertex AI access path.
+Setting `type = "google-vertex"` (or `type = "vertexai"`) connects to Google Gemini models on Google Vertex AI.
 
-Authentication follows the standard Google Cloud ADC flow (`gcloud auth application-default login` or a `GOOGLE_APPLICATION_CREDENTIALS` service account JSON) — this part is unrelated to Kimi Code. **The project ID and region must be written in the `[providers.vertexai.env]` sub-table** — simply `export GOOGLE_CLOUD_PROJECT` in the shell will not be read by the CLI.
+Authentication supports a GCP service account JSON file (`service_account_file`, with `~` path expansion support), an environment variable (`GOOGLE_APPLICATION_CREDENTIALS`), or the standard ADC flow (`gcloud auth application-default login`).
 
 ```toml
-[providers.vertexai]
-type = "vertexai"
-
-[providers.vertexai.env]
-GOOGLE_CLOUD_PROJECT = "my-gcp-project"
-GOOGLE_CLOUD_LOCATION = "us-central1"
+[providers.vertex]
+type = "google-vertex"
+service_account_file = "~/.secrets/my-service-account.json"
+location = "us-central1"
 ```
 
-```sh
-gcloud auth application-default login   # one-time authentication
-kimi
-```
+When `service_account_file` is specified, Kimi Code automatically reads `project_id` from the service account JSON if `project` is omitted.
+
+To route Vertex requests through a custom (e.g. proxied) endpoint, set `base_url` (or the `GOOGLE_VERTEX_BASE_URL` env var).
+
+## `google-vertex-anthropic`
 
-To route Vertex requests through a custom (e.g. proxied) endpoint, set `base_url` (or the `GOOGLE_VERTEX_BASE_URL` env var); when omitted, the SDK default regional `*-aiplatform.googleapis.com` host is used. As with `google-genai`, give the host root only — the SDK appends `/v1beta1/publishers/google/models/…` itself.
+Setting `type = "google-vertex-anthropic"` connects to Anthropic Claude models served on Google Vertex AI.
+
+```toml
+[providers.vertex-claude]
+type = "google-vertex-anthropic"
+service_account_file = "~/.secrets/my-service-account.json"
+location = "us-east5"
+```
 
 ## OAuth and credential injection
 
diff --git a/docs/zh/configuration/providers.md b/docs/zh/configuration/providers.md
index f97df28030..151dd1fd1d 100644
--- a/docs/zh/configuration/providers.md
+++ b/docs/zh/configuration/providers.md
@@ -130,27 +130,33 @@ api_key = "xxxxx"
 base_url = "https://your-gateway.example"
 ```
 
-## `vertexai`
+## `google-vertex` / `vertexai`
 
-与 `google-genai` 共用实现，`type = "vertexai"` 时切换到 Vertex AI 访问路径。
+设置 `type = "google-vertex"`（或 `type = "vertexai"`）连接 Google Vertex AI 上的 Gemini 模型。
 
-认证走 Google Cloud 标准 ADC 流程（`gcloud auth application-default login` 或 `GOOGLE_APPLICATION_CREDENTIALS` 服务账号 JSON），这部分与 Kimi Code 无关。**项目 ID 和区域必须写在 `[providers.vertexai.env]` 子表里**——直接在 shell 里 `export GOOGLE_CLOUD_PROJECT` 不会被 CLI 读取。
+认证支持 GCP 服务账号 JSON 文件（`service_account_file`，支持 `~` 路径展开）、环境变量（`GOOGLE_APPLICATION_CREDENTIALS`）或标准 ADC 流程（`gcloud auth application-default login`）。
 
 ```toml
-[providers.vertexai]
-type = "vertexai"
-
-[providers.vertexai.env]
-GOOGLE_CLOUD_PROJECT = "my-gcp-project"
-GOOGLE_CLOUD_LOCATION = "us-central1"
+[providers.vertex]
+type = "google-vertex"
+service_account_file = "~/.secrets/my-service-account.json"
+location = "us-central1"
 ```
 
-```sh
-gcloud auth application-default login   # 一次性完成认证
-kimi
-```
+指定 `service_account_file` 时，如果未填 `project`，Kimi Code 会自动从服务账号 JSON 中读取 `project_id`。
+
+如需让 Vertex 请求走自定义（如代理）端点，可设置 `base_url`（或 `GOOGLE_VERTEX_BASE_URL` 环境变量）。
+
+## `google-vertex-anthropic`
 
-如需让 Vertex 请求走自定义（如代理）端点，可设置 `base_url`（或 `GOOGLE_VERTEX_BASE_URL` 环境变量）；不填时使用 SDK 默认的区域化 `*-aiplatform.googleapis.com` 地址。与 `google-genai` 一样，只填主机根地址——SDK 会自行追加 `/v1beta1/publishers/google/models/…`。
+设置 `type = "google-vertex-anthropic"` 连接 Google Vertex AI 托管的 Anthropic Claude 模型。
+
+```toml
+[providers.vertex-claude]
+type = "google-vertex-anthropic"
+service_account_file = "~/.secrets/my-service-account.json"
+location = "us-east5"
+```
 
 ## OAuth 与凭证注入
 
diff --git a/packages/acp-adapter/src/server.ts b/packages/acp-adapter/src/server.ts
index 6707fd4cae..de88d9cbb2 100644
--- a/packages/acp-adapter/src/server.ts
+++ b/packages/acp-adapter/src/server.ts
@@ -161,9 +161,15 @@ function providerHasNonOAuthCredentials(provider: ProviderConfig): boolean {
     case 'google-genai':
       return hasProviderValue(provider, 'GOOGLE_API_KEY');
     case 'vertexai':
+    case 'google-vertex':
+    case 'google-vertex-anthropic':
       return (
         hasProviderValue(provider, 'VERTEXAI_API_KEY') ||
         hasEnvValue(provider, 'GOOGLE_API_KEY') ||
+        hasEnvValue(provider, 'ANTHROPIC_API_KEY') ||
+        nonEmptyString(provider.serviceAccountFile) !== undefined ||
+        hasEnvValue(provider, 'GOOGLE_APPLICATION_CREDENTIALS') ||
+        hasEnvValue(provider, 'SERVICE_ACCOUNT_FILE') ||
         (hasEnvValue(provider, 'GOOGLE_CLOUD_PROJECT') &&
           (hasEnvValue(provider, 'GOOGLE_CLOUD_LOCATION') ||
             vertexAILocationFromBaseUrl(provider.baseUrl) !== undefined))
diff --git a/packages/acp-adapter/test/auth-gate.test.ts b/packages/acp-adapter/test/auth-gate.test.ts
index a2fe7e5156..c183433695 100644
--- a/packages/acp-adapter/test/auth-gate.test.ts
+++ b/packages/acp-adapter/test/auth-gate.test.ts
@@ -245,6 +245,22 @@ describe('AcpServer auth gate', () => {
     expect(createCalls).toHaveLength(0);
   });
 
+  it('accepts Vertex AI service-account file config', async () => {
+    const { harness, createCalls } = makeHarnessWithConfig(
+      configuredModelConfig({
+        type: 'google-vertex',
+        serviceAccountFile: '~/.secrets/sa.json',
+      }),
+    );
+
+    const { agentStream, clientStream } = makeInMemoryStreamPair();
+    startAcpServer(harness, agentStream);
+    const client = new ClientSideConnection((_a) => new StubClient(), clientStream);
+
+    await client.newSession({ cwd: '/tmp/vertexai', mcpServers: [] });
+    expect(createCalls).toHaveLength(1);
+  });
+
   it('keeps the OAuth token short-circuit even when config loading fails', async () => {
     const createCalls: Array<{ id?: string; workDir: string }> = [];
     const harness = {
diff --git a/packages/agent-core-v2/docs/config-manifest.toml b/packages/agent-core-v2/docs/config-manifest.toml
index f36724a396..978191725a 100644
--- a/packages/agent-core-v2/docs/config-manifest.toml
+++ b/packages/agent-core-v2/docs/config-manifest.toml
@@ -308,6 +308,9 @@ merge_all_available_skills = true
   # default_model: string
   # type: string
   # api_key: string
+  # service_account_file: string
+  # project: string
+  # location: string
   # oauth: object
     # storage: "file" | "keyring"
     # key: string
diff --git a/packages/agent-core-v2/package.json b/packages/agent-core-v2/package.json
index cfd76230c2..b04c5c0762 100644
--- a/packages/agent-core-v2/package.json
+++ b/packages/agent-core-v2/package.json
@@ -58,6 +58,7 @@
     "@antfu/utils": "^9.3.0",
     "@anthropic-ai/sdk": "^0.95.2",
     "@google/genai": "^1.49.0",
+    "google-auth-library": "^10.6.2",
     "@jsquash/webp": "^1.5.0",
     "@modelcontextprotocol/sdk": "^1.29.0",
     "@moonshot-ai/kimi-code-oauth": "workspace:^",
diff --git a/packages/agent-core-v2/src/app/kosongConfig/configSection.ts b/packages/agent-core-v2/src/app/kosongConfig/configSection.ts
index b7870ca0ae..789a6e86f7 100644
--- a/packages/agent-core-v2/src/app/kosongConfig/configSection.ts
+++ b/packages/agent-core-v2/src/app/kosongConfig/configSection.ts
@@ -47,6 +47,9 @@ export const ProviderConfigSchema = z.object({
 
   type: ProviderTypeSchema.optional(),
   apiKey: z.string().optional(),
+  serviceAccountFile: z.string().optional(),
+  project: z.string().optional(),
+  location: z.string().optional(),
   oauth: OAuthRefSchema.optional(),
   env: StringRecordSchema.optional(),
   source: z.record(z.string(), z.unknown()).optional(),
diff --git a/packages/agent-core-v2/src/kosong/model/catalogService.ts b/packages/agent-core-v2/src/kosong/model/catalogService.ts
index eec2673161..9c39c5e503 100644
--- a/packages/agent-core-v2/src/kosong/model/catalogService.ts
+++ b/packages/agent-core-v2/src/kosong/model/catalogService.ts
@@ -20,6 +20,7 @@ import {
   matchKnownAnthropicModelProfile,
   matchUnknownClaudeProfile,
 } from '../provider/bases/anthropic/anthropic-profile';
+import { expandHomePath, tryReadProjectIdFromServiceAccount } from '../provider/bases/vertex-utils';
 import {
   IProviderService,
   type ProviderConfig,
@@ -558,12 +559,23 @@ function buildProtocolProviderOptions(
   const options: MutableProtocolProviderOptions = {};
 
   switch (protocol) {
-    case 'anthropic':
+    case 'anthropic': {
       if (model.maxOutputSize !== undefined) options.defaultMaxTokens = model.maxOutputSize;
       if (model.supportEfforts !== undefined) options.supportEfforts = model.supportEfforts;
       if (model.adaptiveThinking !== undefined) options.adaptiveThinking = model.adaptiveThinking;
       if (model.betaApi !== undefined) options.betaApi = model.betaApi;
+      const saFile = vertexAIServiceAccountFile(provider);
+      const project = vertexAIProject(provider, saFile);
+      const location = vertexAILocation(provider, baseUrl);
+      const isVertex = provider?.type === 'google-vertex-anthropic' || saFile !== undefined;
+      if (isVertex) {
+        options.vertexai = true;
+        if (saFile !== undefined) options.serviceAccountFile = saFile;
+        if (project !== undefined) options.project = project;
+        if (location !== undefined) options.location = location;
+      }
       break;
+    }
     case 'openai': {
       const reasoningKey = nonEmpty(model.reasoningKey);
       if (reasoningKey !== undefined) options.reasoningKey = reasoningKey;
@@ -571,12 +583,19 @@ function buildProtocolProviderOptions(
       break;
     }
     case 'google-genai': {
-      const project = vertexAIProject(provider);
+      const saFile = vertexAIServiceAccountFile(provider);
+      const project = vertexAIProject(provider, saFile);
       const location = vertexAILocation(provider, baseUrl);
-      if (project !== undefined && location !== undefined) {
+      const isVertex =
+        provider?.type === 'vertexai' ||
+        provider?.type === 'google-vertex' ||
+        saFile !== undefined ||
+        (project !== undefined && location !== undefined);
+      if (isVertex) {
         options.vertexai = true;
-        options.project = project;
-        options.location = location;
+        if (saFile !== undefined) options.serviceAccountFile = saFile;
+        if (project !== undefined) options.project = project;
+        if (location !== undefined) options.location = location;
       }
       break;
     }
@@ -614,15 +633,37 @@ function profileForAttribution(
   return { profile: known, inferred: false };
 }
 
-function vertexAIProject(provider: ProviderConfig | undefined): string | undefined {
-  return envValue(provider?.env, 'GOOGLE_CLOUD_PROJECT');
+function vertexAIServiceAccountFile(provider: ProviderConfig | undefined): string | undefined {
+  const configured =
+    nonEmpty(provider?.serviceAccountFile) ??
+    (typeof provider?.source?.['service_account_file'] === 'string'
+      ? nonEmpty(provider.source['service_account_file'] as string)
+      : undefined);
+  const rawPath =
+    configured ??
+    envValue(provider?.env, 'GOOGLE_APPLICATION_CREDENTIALS') ??
+    envValue(provider?.env, 'SERVICE_ACCOUNT_FILE');
+  return expandHomePath(rawPath);
+}
+
+function vertexAIProject(provider: ProviderConfig | undefined, saFile?: string): string | undefined {
+  const saPath = saFile ?? vertexAIServiceAccountFile(provider);
+  return (
+    nonEmpty(provider?.project) ??
+    envValue(provider?.env, 'GOOGLE_CLOUD_PROJECT') ??
+    tryReadProjectIdFromServiceAccount(saPath)
+  );
 }
 
 function vertexAILocation(
   provider: ProviderConfig | undefined,
   baseUrl: string | undefined,
 ): string | undefined {
-  return envValue(provider?.env, 'GOOGLE_CLOUD_LOCATION') ?? locationFromVertexAIBaseUrl(baseUrl);
+  return (
+    nonEmpty(provider?.location) ??
+    envValue(provider?.env, 'GOOGLE_CLOUD_LOCATION') ??
+    locationFromVertexAIBaseUrl(baseUrl)
+  );
 }
 
 function envValue(env: Record<string, string> | undefined, key: string): string | undefined {
diff --git a/packages/agent-core-v2/src/kosong/protocol/protocol.ts b/packages/agent-core-v2/src/kosong/protocol/protocol.ts
index b0c38f90ac..27b3b40a28 100644
--- a/packages/agent-core-v2/src/kosong/protocol/protocol.ts
+++ b/packages/agent-core-v2/src/kosong/protocol/protocol.ts
@@ -27,6 +27,7 @@ export interface ProtocolProviderOptions {
   readonly vertexai?: boolean;
   readonly project?: string;
   readonly location?: string;
+  readonly serviceAccountFile?: string;
 }
 
 export interface ProtocolAdapterConfig {
diff --git a/packages/agent-core-v2/src/kosong/provider/bases/anthropic/anthropic.contrib.ts b/packages/agent-core-v2/src/kosong/provider/bases/anthropic/anthropic.contrib.ts
index 64fc2d70b5..0a8ca46e26 100644
--- a/packages/agent-core-v2/src/kosong/provider/bases/anthropic/anthropic.contrib.ts
+++ b/packages/agent-core-v2/src/kosong/provider/bases/anthropic/anthropic.contrib.ts
@@ -22,6 +22,10 @@ registerProtocolBase({
         adaptiveThinking: config.providerOptions?.adaptiveThinking,
         supportEfforts: config.providerOptions?.supportEfforts,
         betaApi: config.providerOptions?.betaApi,
+        vertexai: config.providerOptions?.vertexai,
+        project: config.providerOptions?.project,
+        location: config.providerOptions?.location,
+        serviceAccountFile: config.providerOptions?.serviceAccountFile,
         metadata:
           config.providerOptions?.metadata === undefined
             ? undefined
diff --git a/packages/agent-core-v2/src/kosong/provider/bases/anthropic/anthropic.ts b/packages/agent-core-v2/src/kosong/provider/bases/anthropic/anthropic.ts
index 77576d00fc..dabbf0597c 100644
--- a/packages/agent-core-v2/src/kosong/provider/bases/anthropic/anthropic.ts
+++ b/packages/agent-core-v2/src/kosong/provider/bases/anthropic/anthropic.ts
@@ -49,6 +49,8 @@ import type {
 import type { Tool } from '#/kosong/contract/tool';
 import type { TokenUsage } from '#/kosong/contract/usage';
 
+import { GoogleAuth } from 'google-auth-library';
+
 import {
   BUDGET_THINKING_EFFORTS,
   inferAnthropicModelProfile,
@@ -60,6 +62,7 @@ import {
 import { mergeConsecutiveUserMessages } from '../merge-user-messages';
 import { mergeRequestHeaders, resolveAuthBackedClient } from '../request-auth';
 import { normalizeToolCallIdsForProvider, sanitizeToolCallId } from '../tool-call-id';
+import { expandHomePath, tryReadProjectIdFromServiceAccount } from '../vertex-utils';
 
 function normalizeAnthropicStopReason(raw: string | null | undefined): {
   finishReason: FinishReason | null;
@@ -122,6 +125,11 @@ export interface AnthropicOptions {
   supportEfforts?: readonly string[] | undefined;
   betaApi?: boolean | undefined;
   thinkingEffort?: ThinkingEffort | undefined;
+  vertexai?: boolean | undefined;
+  project?: string | undefined;
+  location?: string | undefined;
+  serviceAccountFile?: string | undefined;
+  googleAuthOptions?: Record<string, unknown> | undefined;
   clientFactory?: (auth: ProviderRequestAuth) => Anthropic;
   hooks?: AnthropicHooks | undefined;
 }
@@ -776,7 +784,7 @@ export class AnthropicChatProvider implements ChatProvider {
 
   private readonly _model: string;
   private readonly _stream: boolean;
-  private readonly _client: Anthropic | undefined;
+  private _client: Anthropic | undefined;
   private readonly _generationKwargs: AnthropicGenerationKwargs;
   private readonly _metadata: Record<string, string> | undefined;
   private readonly _apiKey: string | undefined;
@@ -789,6 +797,11 @@ export class AnthropicChatProvider implements ChatProvider {
   private readonly _thinkingEffort: ThinkingEffort | undefined;
   private readonly _explicitMaxTokens: boolean;
   private readonly _hooks: AnthropicHooks | undefined;
+  private readonly _vertexai: boolean;
+  private readonly _project: string | undefined;
+  private readonly _location: string | undefined;
+  private readonly _serviceAccountFile: string | undefined;
+  private readonly _googleAuthOptions: Record<string, unknown> | undefined;
 
   constructor(options: AnthropicOptions) {
     this._model = options.model;
@@ -799,12 +812,40 @@ export class AnthropicChatProvider implements ChatProvider {
     this._betaApi = options.betaApi ?? false;
     this._thinkingEffort = options.thinkingEffort;
     this._hooks = options.hooks;
+    this._vertexai = options.vertexai ?? false;
     this._apiKey =
       options.apiKey === undefined || options.apiKey.length === 0 ? undefined : options.apiKey;
     this._baseUrl = options.baseUrl;
     this._defaultHeaders = options.defaultHeaders;
     this._clientFactory = options.clientFactory;
-    this._client = this._apiKey === undefined ? undefined : this._buildClient(this._apiKey);
+
+    const rawSaFile =
+      options.serviceAccountFile ??
+      process.env['GOOGLE_APPLICATION_CREDENTIALS'] ??
+      process.env['SERVICE_ACCOUNT_FILE'];
+    this._serviceAccountFile = expandHomePath(rawSaFile);
+    this._googleAuthOptions =
+      options.googleAuthOptions ??
+      (this._serviceAccountFile !== undefined
+        ? {
+            keyFilename: this._serviceAccountFile,
+            scopes: ['https://www.googleapis.com/auth/cloud-platform'],
+          }
+        : undefined);
+
+    this._project =
+      options.project ??
+      (this._serviceAccountFile !== undefined
+        ? tryReadProjectIdFromServiceAccount(this._serviceAccountFile)
+        : undefined) ??
+      process.env['GOOGLE_CLOUD_PROJECT'];
+    this._location = options.location ?? process.env['GOOGLE_CLOUD_LOCATION'] ?? 'us-central1';
+
+    this._client = this._vertexai
+      ? this._buildVertexClient()
+      : this._apiKey === undefined
+        ? undefined
+        : this._buildClient(this._apiKey);
     this._explicitMaxTokens = options.defaultMaxTokens !== undefined;
     this._generationKwargs = {
       max_tokens: options.defaultMaxTokens ?? resolveDefaultMaxTokens(options.model),
@@ -1072,6 +1113,12 @@ export class AnthropicChatProvider implements ChatProvider {
   }
 
   private _createClient(auth: ProviderRequestAuth | undefined): Anthropic {
+    if (this._vertexai) {
+      if (this._client === undefined) {
+        this._client = this._buildVertexClient();
+      }
+      return this._client;
+    }
     return resolveAuthBackedClient(
       { cachedClient: this._client, clientFactory: this._clientFactory },
       auth,
@@ -1116,6 +1163,128 @@ export class AnthropicChatProvider implements ChatProvider {
     return defaultHeaders;
   }
 
+  private _buildVertexClient(): Anthropic {
+    const googleAuth = new GoogleAuth(
+      this._googleAuthOptions ?? {
+        scopes: ['https://www.googleapis.com/auth/cloud-platform'],
+      },
+    );
+
+    const project = this._project;
+    const location = this._location ?? 'us-central1';
+    const customBaseUrl = this._baseUrl;
+
+    const vertexFetch = async (
+      url: string | URL | Request,
+      init?: RequestInit,
+    ): Promise<Response> => {
+      const authObj = googleAuth as {
+        getClient(): Promise<{ getAccessToken(): Promise<{ token?: string | null }> }>;
+      };
+      const client = await authObj.getClient();
+      const tokenResponse = await client.getAccessToken();
+      const token = tokenResponse.token;
+
+      let bodyObj: Record<string, unknown> = {};
+      if (init?.body && typeof init.body === 'string') {
+        try {
+          bodyObj = JSON.parse(init.body) as Record<string, unknown>;
+        } catch {
+          bodyObj = {};
+        }
+      }
+
+      const isStream = bodyObj['stream'] === true;
+      const modelName =
+        (typeof bodyObj['model'] === 'string' ? bodyObj['model'] : this._model) || this._model;
+      delete bodyObj['model'];
+      delete bodyObj['stream'];
+      bodyObj['anthropic_version'] = 'vertex-2023-10-16';
+
+      const verb = isStream ? 'streamRawPredict' : 'rawPredict';
+
+      let targetUrl: string;
+      if (customBaseUrl && customBaseUrl.length > 0) {
+        const cleanBase = customBaseUrl.replace(/\/+$/, '');
+        targetUrl = `${cleanBase}/v1/projects/${project}/locations/${location}/publishers/anthropic/models/${modelName}:${verb}`;
+      } else {
+        const host =
+          location === 'global'
+            ? 'aiplatform.googleapis.com'
+            : `${location}-aiplatform.googleapis.com`;
+        targetUrl = `https://${host}/v1/projects/${project}/locations/${location}/publishers/anthropic/models/${modelName}:${verb}`;
+      }
+
+      const headers = new Headers(init?.headers);
+      if (token) {
+        headers.set('Authorization', `Bearer ${token}`);
+      }
+      headers.set('Content-Type', 'application/json');
+
+      const newInit: RequestInit = {
+        ...init,
+        headers,
+        body: JSON.stringify(bodyObj),
+      };
+
+      const res = await fetch(targetUrl, newInit);
+      if (isStream && res.status === 200) {
+        const contentType = res.headers.get('content-type') ?? '';
+        if (!contentType.includes('text/event-stream')) {
+          const json = (await res.json()) as Record<string, unknown>;
+          const content =
+            (json['content'] as Array<{ type: string; text?: string; thinking?: string }>) || [];
+          const sseParts: string[] = [
+            `event: message_start\ndata: ${JSON.stringify({ type: 'message_start', message: json })}\n\n`,
+          ];
+          for (let idx = 0; idx < content.length; idx++) {
+            const c = content[idx]!;
+            if (c.type === 'thinking') {
+              sseParts.push(
+                `event: content_block_start\ndata: ${JSON.stringify({ type: 'content_block_start', index: idx, content_block: { type: 'thinking', thinking: '' } })}\n\n`,
+              );
+              sseParts.push(
+                `event: content_block_delta\ndata: ${JSON.stringify({ type: 'content_block_delta', index: idx, delta: { type: 'thinking_delta', thinking: c.thinking || '' } })}\n\n`,
+              );
+              sseParts.push(
+                `event: content_block_stop\ndata: ${JSON.stringify({ type: 'content_block_stop', index: idx })}\n\n`,
+              );
+            } else {
+              sseParts.push(
+                `event: content_block_start\ndata: ${JSON.stringify({ type: 'content_block_start', index: idx, content_block: { type: 'text', text: '' } })}\n\n`,
+              );
+              sseParts.push(
+                `event: content_block_delta\ndata: ${JSON.stringify({ type: 'content_block_delta', index: idx, delta: { type: 'text_delta', text: c.text || '' } })}\n\n`,
+              );
+              sseParts.push(
+                `event: content_block_stop\ndata: ${JSON.stringify({ type: 'content_block_stop', index: idx })}\n\n`,
+              );
+            }
+          }
+          sseParts.push(
+            `event: message_delta\ndata: ${JSON.stringify({ type: 'message_delta', delta: { stop_reason: json['stop_reason'] || 'end_turn', stop_sequence: json['stop_sequence'] }, usage: json['usage'] })}\n\n`,
+          );
+          sseParts.push(`event: message_stop\ndata: ${JSON.stringify({ type: 'message_stop' })}\n\n`);
+
+          return new Response(sseParts.join(''), {
+            status: 200,
+            headers: { 'Content-Type': 'text/event-stream' },
+          });
+        }
+      }
+      return res;
+    };
+
+    return new Anthropic({
+      apiKey: this._apiKey ?? 'dummy-vertex-key',
+      authToken: null,
+      baseURL: null,
+      fetch: vertexFetch,
+      defaultHeaders: this._buildDefaultHeaders(this._apiKey ?? 'dummy-vertex-key'),
+      maxRetries: 0,
+    });
+  }
+
   private _buildClient(apiKey: string): Anthropic {
     return new Anthropic({
       apiKey,
diff --git a/packages/agent-core-v2/src/kosong/provider/bases/google-genai/google-genai.contrib.ts b/packages/agent-core-v2/src/kosong/provider/bases/google-genai/google-genai.contrib.ts
index b9d2624690..7208e27e50 100644
--- a/packages/agent-core-v2/src/kosong/provider/bases/google-genai/google-genai.contrib.ts
+++ b/packages/agent-core-v2/src/kosong/provider/bases/google-genai/google-genai.contrib.ts
@@ -25,6 +25,7 @@ registerProtocolBase({
         vertexai: config.providerOptions?.vertexai,
         project: config.providerOptions?.project,
         location: config.providerOptions?.location,
+        serviceAccountFile: config.providerOptions?.serviceAccountFile,
       }),
     });
   },
diff --git a/packages/agent-core-v2/src/kosong/provider/bases/google-genai/google-genai.ts b/packages/agent-core-v2/src/kosong/provider/bases/google-genai/google-genai.ts
index b6bc1d5c0b..d930a956a6 100644
--- a/packages/agent-core-v2/src/kosong/provider/bases/google-genai/google-genai.ts
+++ b/packages/agent-core-v2/src/kosong/provider/bases/google-genai/google-genai.ts
@@ -22,6 +22,7 @@ import type { TokenUsage } from '#/kosong/contract/usage';
 
 import { mergeConsecutiveUserMessages } from '../merge-user-messages';
 import { requireProviderApiKey, resolveAuthBackedClient } from '../request-auth';
+import { expandHomePath, tryReadProjectIdFromServiceAccount } from '../vertex-utils';
 
 function normalizeGoogleGenAIFinishReason(raw: unknown): {
   finishReason: FinishReason | null;
@@ -69,6 +70,8 @@ export interface GoogleGenAIOptions {
   vertexai?: boolean | undefined;
   project?: string | undefined;
   location?: string | undefined;
+  serviceAccountFile?: string | undefined;
+  googleAuthOptions?: Record<string, unknown> | undefined;
   stream?: boolean | undefined;
   thinkingEffort?: ThinkingEffort | undefined;
   defaultHeaders?: Record<string, string>;
@@ -100,16 +103,17 @@ interface GoogleTool {
   functionDeclarations: GoogleFunctionDeclaration[];
 }
 
-function toolToGoogleGenAI(tool: Tool): GoogleTool {
-  return {
-    functionDeclarations: [
-      {
+function toolsToGoogleGenAI(tools: Tool[]): GoogleTool[] {
+  if (tools.length === 0) return [];
+  return [
+    {
+      functionDeclarations: tools.map((tool) => ({
         name: tool.name,
         description: tool.description,
         parametersJsonSchema: tool.parameters,
-      },
-    ],
-  };
+      })),
+    },
+  ];
 }
 
 function applyResponseFormat(
@@ -681,6 +685,8 @@ export class GoogleGenAIChatProvider implements ChatProvider {
   private readonly _baseUrl: string | undefined;
   private readonly _project: string | undefined;
   private readonly _location: string | undefined;
+  private readonly _serviceAccountFile: string | undefined;
+  private readonly _googleAuthOptions: Record<string, unknown> | undefined;
   private readonly _thinkingEffort: ThinkingEffort | undefined;
   private readonly _defaultHeaders: Record<string, string> | undefined;
   private readonly _clientFactory: ((auth: ProviderRequestAuth) => GenAIClient) | undefined;
@@ -696,12 +702,34 @@ export class GoogleGenAIChatProvider implements ChatProvider {
     this._apiKey = apiKey === undefined || apiKey.length === 0 ? undefined : apiKey;
     this._baseUrl =
       options.baseUrl === undefined || options.baseUrl.length === 0 ? undefined : options.baseUrl;
-    this._project = options.project;
-    this._location = options.location;
+
+    const rawSaFile =
+      options.serviceAccountFile ??
+      process.env['GOOGLE_APPLICATION_CREDENTIALS'] ??
+      process.env['SERVICE_ACCOUNT_FILE'];
+    this._serviceAccountFile = expandHomePath(rawSaFile);
+    this._googleAuthOptions =
+      options.googleAuthOptions ??
+      (this._serviceAccountFile !== undefined
+        ? {
+            keyFilename: this._serviceAccountFile,
+            scopes: ['https://www.googleapis.com/auth/cloud-platform'],
+          }
+        : undefined);
+
+    this._project =
+      options.project ??
+      (this._serviceAccountFile !== undefined
+        ? tryReadProjectIdFromServiceAccount(this._serviceAccountFile)
+        : undefined) ??
+      process.env['GOOGLE_CLOUD_PROJECT'];
+    this._location = options.location ?? process.env['GOOGLE_CLOUD_LOCATION'];
     this._defaultHeaders = options.defaultHeaders;
     this._clientFactory = options.clientFactory;
     this._client =
-      this._vertexai || this._apiKey !== undefined ? this._buildClient(this._apiKey) : undefined;
+      this._vertexai || this._apiKey !== undefined || this._googleAuthOptions !== undefined
+        ? this._buildClient(this._apiKey)
+        : undefined;
   }
 
   private _buildClient(apiKey: string | undefined): GenAIClient {
@@ -719,6 +747,9 @@ export class GoogleGenAIChatProvider implements ChatProvider {
             vertexai: true,
             project: this._project,
             location: this._location,
+            ...(this._googleAuthOptions !== undefined
+              ? { googleAuthOptions: this._googleAuthOptions }
+              : {}),
           }
         : {}),
       httpOptions: Object.keys(httpOptions).length > 0 ? httpOptions : undefined,
@@ -780,7 +811,7 @@ export class GoogleGenAIChatProvider implements ChatProvider {
     const config: Record<string, unknown> = {
       ...kwargs,
       systemInstruction: systemPrompt,
-      ...(tools.length > 0 ? { tools: tools.map((t) => toolToGoogleGenAI(t)) } : {}),
+      ...(tools.length > 0 ? { tools: toolsToGoogleGenAI(tools) } : {}),
     };
     applyResponseFormat(config, options?.responseFormat);
 
diff --git a/packages/agent-core-v2/src/kosong/provider/bases/vertex-utils.ts b/packages/agent-core-v2/src/kosong/provider/bases/vertex-utils.ts
new file mode 100644
index 0000000000..bc01f8d41d
--- /dev/null
+++ b/packages/agent-core-v2/src/kosong/provider/bases/vertex-utils.ts
@@ -0,0 +1,30 @@
+import { readFileSync } from 'node:fs';
+import { homedir } from 'node:os';
+import { join } from 'node:path';
+
+export function expandHomePath(filePath: string | undefined): string | undefined {
+  if (filePath === undefined) return undefined;
+  const trimmed = filePath.trim();
+  if (trimmed.length === 0) return undefined;
+  if (trimmed === '~') return homedir();
+  if (trimmed.startsWith('~/') || trimmed.startsWith('~\\')) {
+    return join(homedir(), trimmed.slice(2));
+  }
+  return trimmed;
+}
+
+export function tryReadProjectIdFromServiceAccount(filePath: string | undefined): string | undefined {
+  if (filePath === undefined) return undefined;
+  const expanded = expandHomePath(filePath);
+  if (expanded === undefined) return undefined;
+  try {
+    const content = readFileSync(expanded, 'utf8');
+    const parsed = JSON.parse(content) as Record<string, unknown>;
+    if (typeof parsed['project_id'] === 'string' && parsed['project_id'].length > 0) {
+      return parsed['project_id'];
+    }
+  } catch {
+    return undefined;
+  }
+  return undefined;
+}
diff --git a/packages/agent-core-v2/src/kosong/provider/provider.ts b/packages/agent-core-v2/src/kosong/provider/provider.ts
index e6436506d2..8975b2095b 100644
--- a/packages/agent-core-v2/src/kosong/provider/provider.ts
+++ b/packages/agent-core-v2/src/kosong/provider/provider.ts
@@ -20,6 +20,9 @@ export interface ProviderConfig {
 
   type?: ProviderType;
   apiKey?: string;
+  serviceAccountFile?: string;
+  project?: string;
+  location?: string;
   oauth?: OAuthRef;
   env?: Record<string, string>;
   source?: Record<string, unknown>;
diff --git a/packages/agent-core-v2/src/kosong/provider/providers/standard.contrib.ts b/packages/agent-core-v2/src/kosong/provider/providers/standard.contrib.ts
index 6e075737fa..9789f76db0 100644
--- a/packages/agent-core-v2/src/kosong/provider/providers/standard.contrib.ts
+++ b/packages/agent-core-v2/src/kosong/provider/providers/standard.contrib.ts
@@ -29,3 +29,30 @@ registerProviderDefinition({
     { endpoint: () => ({ apiKeyEnv: 'GOOGLE_API_KEY', baseUrlEnv: 'GOOGLE_GEMINI_BASE_URL' }) },
   ],
 });
+
+registerProviderDefinition({
+  id: 'vertexai',
+  baseProtocol: 'google-genai',
+  traits: [
+    { endpoint: () => ({ apiKeyEnv: 'VERTEXAI_API_KEY', baseUrlEnv: 'GOOGLE_VERTEX_BASE_URL' }) },
+    { endpoint: () => ({ apiKeyEnv: 'GOOGLE_API_KEY', baseUrlEnv: 'GOOGLE_GEMINI_BASE_URL' }) },
+  ],
+});
+
+registerProviderDefinition({
+  id: 'google-vertex',
+  baseProtocol: 'google-genai',
+  traits: [
+    { endpoint: () => ({ apiKeyEnv: 'VERTEXAI_API_KEY', baseUrlEnv: 'GOOGLE_VERTEX_BASE_URL' }) },
+    { endpoint: () => ({ apiKeyEnv: 'GOOGLE_API_KEY', baseUrlEnv: 'GOOGLE_GEMINI_BASE_URL' }) },
+  ],
+});
+
+registerProviderDefinition({
+  id: 'google-vertex-anthropic',
+  baseProtocol: 'anthropic',
+  traits: [
+    { endpoint: () => ({ apiKeyEnv: 'VERTEXAI_API_KEY', baseUrlEnv: 'GOOGLE_VERTEX_BASE_URL' }) },
+    { endpoint: () => ({ apiKeyEnv: 'ANTHROPIC_API_KEY', baseUrlEnv: 'ANTHROPIC_BASE_URL' }) },
+  ],
+});
diff --git a/packages/agent-core-v2/test/kosong/model/catalog.test.ts b/packages/agent-core-v2/test/kosong/model/catalog.test.ts
index 98a51a8797..5eeba4bbff 100644
--- a/packages/agent-core-v2/test/kosong/model/catalog.test.ts
+++ b/packages/agent-core-v2/test/kosong/model/catalog.test.ts
@@ -386,6 +386,43 @@ describe('Model assembly (pure data)', () => {
     }
   });
 
+  it('enables google-vertex and google-vertex-anthropic through providerOptions with serviceAccountFile', () => {
+    const { host, catalog } = createHost({
+      providers: {
+        vtx: {
+          type: 'google-vertex',
+          serviceAccountFile: '~/.secrets/sa.json',
+          location: 'us-central1',
+        },
+        vtx_claude: {
+          type: 'google-vertex-anthropic',
+          serviceAccountFile: '~/.secrets/sa.json',
+          project: 'proj-claude',
+          location: 'us-east5',
+        },
+      },
+      models: {
+        v1: { provider: 'vtx', model: 'gemini-2.5-pro', maxContextSize: 1000 },
+        v2: { provider: 'vtx_claude', model: 'claude-sonnet-4-6', maxContextSize: 1000 },
+      },
+    });
+    try {
+      expect(catalog.get('v1').providerOptions).toMatchObject({
+        vertexai: true,
+        serviceAccountFile: expect.stringContaining('.secrets/sa.json'),
+        location: 'us-central1',
+      });
+      expect(catalog.get('v2').providerOptions).toMatchObject({
+        vertexai: true,
+        serviceAccountFile: expect.stringContaining('.secrets/sa.json'),
+        project: 'proj-claude',
+        location: 'us-east5',
+      });
+    } finally {
+      host.dispose();
+    }
+  });
+
   it('supports flat models with an inline baseUrl (provider synthesized from the origin)', () => {
     const { host, catalog } = createHost({
       models: {
diff --git a/packages/agent-core/src/config/schema.ts b/packages/agent-core/src/config/schema.ts
index 62770fde97..63a7a13d50 100644
--- a/packages/agent-core/src/config/schema.ts
+++ b/packages/agent-core/src/config/schema.ts
@@ -10,6 +10,8 @@ export const ProviderTypeSchema = z.enum([
   'google-genai',
   'openai_responses',
   'vertexai',
+  'google-vertex',
+  'google-vertex-anthropic',
 ]);
 
 export type ProviderType = z.infer<typeof ProviderTypeSchema>;
@@ -29,6 +31,9 @@ export const ProviderConfigSchema = z.object({
   apiKey: z.string().optional(),
   baseUrl: z.string().optional(),
   defaultModel: z.string().optional(),
+  serviceAccountFile: z.string().optional(),
+  project: z.string().optional(),
+  location: z.string().optional(),
   oauth: OAuthRefSchema.optional(),
   env: StringRecordSchema.optional(),
   customHeaders: StringRecordSchema.optional(),
diff --git a/packages/agent-core/src/session/provider-manager.ts b/packages/agent-core/src/session/provider-manager.ts
index 7fb313b461..a7ac97a6c5 100644
--- a/packages/agent-core/src/session/provider-manager.ts
+++ b/packages/agent-core/src/session/provider-manager.ts
@@ -3,7 +3,9 @@ import type { ProviderConfig as KosongProviderConfig, ModelCapability, ProviderR
 import {
   APIStatusError,
   classifyKimiQuotaError,
+  expandHomePath,
   getModelCapability,
+  tryReadProjectIdFromServiceAccount,
   UNKNOWN_CAPABILITY,
 } from '@moonshot-ai/kosong';
 import { parseKimiCodeCustomHeaders } from '@moonshot-ai/kimi-code-oauth';
@@ -379,7 +381,8 @@ function toKosongProviderConfig(
           ...provider.customHeaders,
         }),
       };
-    case 'vertexai': {
+    case 'vertexai':
+    case 'google-vertex': {
       // Resolve the effective endpoint once (config `base_url` or the
       // GOOGLE_VERTEX_BASE_URL env fallback) and use it for BOTH forwarding and
       // location detection, so the env fallback behaves exactly like
@@ -387,14 +390,36 @@ function toKosongProviderConfig(
       // `*-aiplatform.googleapis.com` host for the service-account path.
       const baseUrl =
         modelBaseUrl ?? providerValue(provider.baseUrl, provider.env, 'GOOGLE_VERTEX_BASE_URL');
+      const saFile = vertexAIServiceAccountFile(provider);
       const useServiceAccount = hasVertexAIServiceEnv(provider, baseUrl);
       return {
-        type: 'vertexai',
+        type: provider.type,
         model,
         vertexai: useServiceAccount,
         baseUrl,
         apiKey: useServiceAccount ? undefined : providerApiKey(provider),
-        project: vertexAIProject(provider),
+        serviceAccountFile: saFile,
+        project: vertexAIProject(provider, saFile),
+        location: vertexAILocation(provider, baseUrl),
+        ...defaultHeadersField({
+          ...envCustomHeaders,
+          ...kimiUserAgentHeader(kimiRequestHeaders),
+          ...provider.customHeaders,
+        }),
+      };
+    }
+    case 'google-vertex-anthropic': {
+      const baseUrl =
+        modelBaseUrl ?? providerValue(provider.baseUrl, provider.env, 'GOOGLE_VERTEX_BASE_URL');
+      const saFile = vertexAIServiceAccountFile(provider);
+      return {
+        type: 'google-vertex-anthropic',
+        model,
+        vertexai: true,
+        baseUrl,
+        apiKey: providerApiKey(provider),
+        serviceAccountFile: saFile,
+        project: vertexAIProject(provider, saFile),
         location: vertexAILocation(provider, baseUrl),
         ...defaultHeadersField({
           ...envCustomHeaders,
@@ -448,10 +473,13 @@ function providerApiKey(provider: ProviderConfig): string | undefined {
     case 'google-genai':
       return providerValue(provider.apiKey, provider.env, 'GOOGLE_API_KEY');
     case 'vertexai':
+    case 'google-vertex':
+    case 'google-vertex-anthropic':
       return (
         nonEmptyString(provider.apiKey) ??
         envValue(provider.env, 'VERTEXAI_API_KEY') ??
-        envValue(provider.env, 'GOOGLE_API_KEY')
+        envValue(provider.env, 'GOOGLE_API_KEY') ??
+        envValue(provider.env, 'ANTHROPIC_API_KEY')
       );
     default: {
       const exhaustive: never = provider.type;
@@ -463,19 +491,46 @@ function providerApiKey(provider: ProviderConfig): string | undefined {
   }
 }
 
+function vertexAIServiceAccountFile(provider: ProviderConfig): string | undefined {
+  const configured =
+    nonEmptyString(provider.serviceAccountFile) ??
+    (typeof provider.source?.['service_account_file'] === 'string'
+      ? nonEmptyString(provider.source['service_account_file'] as string)
+      : undefined);
+  const rawPath =
+    configured ??
+    envValue(provider.env, 'GOOGLE_APPLICATION_CREDENTIALS') ??
+    envValue(provider.env, 'SERVICE_ACCOUNT_FILE');
+  return expandHomePath(rawPath);
+}
+
 function hasVertexAIServiceEnv(provider: ProviderConfig, baseUrl: string | undefined): boolean {
-  return vertexAIProject(provider) !== undefined && vertexAILocation(provider, baseUrl) !== undefined;
+  const saFile = vertexAIServiceAccountFile(provider);
+  return (
+    saFile !== undefined ||
+    (vertexAIProject(provider, saFile) !== undefined &&
+      vertexAILocation(provider, baseUrl) !== undefined)
+  );
 }
 
-function vertexAIProject(provider: ProviderConfig): string | undefined {
-  return envValue(provider.env, 'GOOGLE_CLOUD_PROJECT');
+function vertexAIProject(provider: ProviderConfig, saFile?: string): string | undefined {
+  const saPath = saFile ?? vertexAIServiceAccountFile(provider);
+  return (
+    nonEmptyString(provider.project) ??
+    envValue(provider.env, 'GOOGLE_CLOUD_PROJECT') ??
+    tryReadProjectIdFromServiceAccount(saPath)
+  );
 }
 
 function vertexAILocation(
   provider: ProviderConfig,
   baseUrl: string | undefined,
 ): string | undefined {
-  return envValue(provider.env, 'GOOGLE_CLOUD_LOCATION') ?? locationFromVertexAIBaseUrl(baseUrl);
+  return (
+    nonEmptyString(provider.location) ??
+    envValue(provider.env, 'GOOGLE_CLOUD_LOCATION') ??
+    locationFromVertexAIBaseUrl(baseUrl)
+  );
 }
 
 function providerValue(
diff --git a/packages/agent-core/test/harness/runtime-provider.test.ts b/packages/agent-core/test/harness/runtime-provider.test.ts
index 5f26a2d599..7e26f3201d 100644
--- a/packages/agent-core/test/harness/runtime-provider.test.ts
+++ b/packages/agent-core/test/harness/runtime-provider.test.ts
@@ -1236,6 +1236,58 @@ describe('google base URL forwarding', () => {
       location: 'us-central1',
     });
   });
+
+  it('resolves google-vertex provider with serviceAccountFile and tilde expansion', () => {
+    const resolved = resolveRuntimeProvider({
+      config: {
+        defaultModel: 'gemini',
+        providers: {
+          vtx: {
+            type: 'google-vertex',
+            serviceAccountFile: '~/.secrets/my-sa.json',
+            location: 'us-central1',
+          },
+        },
+        models: {
+          gemini: { provider: 'vtx', model: 'gemini-2.5-pro', maxContextSize: 1_000_000 },
+        },
+      },
+    });
+
+    expect(resolved.provider).toMatchObject({
+      type: 'google-vertex',
+      vertexai: true,
+      serviceAccountFile: expect.stringContaining('.secrets/my-sa.json'),
+      location: 'us-central1',
+    });
+  });
+
+  it('resolves google-vertex-anthropic provider with serviceAccountFile', () => {
+    const resolved = resolveRuntimeProvider({
+      config: {
+        defaultModel: 'claude',
+        providers: {
+          vtx_claude: {
+            type: 'google-vertex-anthropic',
+            serviceAccountFile: '~/.secrets/my-sa.json',
+            project: 'proj-123',
+            location: 'us-east5',
+          },
+        },
+        models: {
+          claude: { provider: 'vtx_claude', model: 'claude-sonnet-4-6', maxContextSize: 200_000 },
+        },
+      },
+    });
+
+    expect(resolved.provider).toMatchObject({
+      type: 'google-vertex-anthropic',
+      vertexai: true,
+      serviceAccountFile: expect.stringContaining('.secrets/my-sa.json'),
+      project: 'proj-123',
+      location: 'us-east5',
+    });
+  });
 });
 
 describe('per-model protocol routing', () => {
diff --git a/packages/kosong/package.json b/packages/kosong/package.json
index 6ac04bc839..3f16ac781e 100644
--- a/packages/kosong/package.json
+++ b/packages/kosong/package.json
@@ -45,6 +45,7 @@
   "dependencies": {
     "@anthropic-ai/sdk": "^0.95.2",
     "@google/genai": "^1.49.0",
+    "google-auth-library": "^10.6.2",
     "openai": "^6.34.0",
     "zod": "^4.3.6",
     "zod-to-json-schema": "^3.25.2"
diff --git a/packages/kosong/src/catalog.ts b/packages/kosong/src/catalog.ts
index 6c7c611c81..3e3ee959a7 100644
--- a/packages/kosong/src/catalog.ts
+++ b/packages/kosong/src/catalog.ts
@@ -101,6 +101,8 @@ const KNOWN_WIRE_TYPES = [
   'google-genai',
   'openai_responses',
   'vertexai',
+  'google-vertex',
+  'google-vertex-anthropic',
 ] as const satisfies readonly ProviderType[];
 
 function isWireType(value: unknown): value is ProviderType {
@@ -244,6 +246,10 @@ function inferDeclaredWireType(entry: CatalogProviderEntry): ProviderType | unde
   if (isWireType(entry.type)) return entry.type;
   const npm = (entry.npm ?? '').toLowerCase();
   const id = (entry.id ?? '').toLowerCase();
+  if (id === 'google-vertex-anthropic' || npm.includes('google-vertex/anthropic') || id.includes('vertex-anthropic')) {
+    return 'google-vertex-anthropic';
+  }
+  if (id === 'google-vertex') return 'google-vertex';
   if (npm.includes('anthropic') || id.includes('anthropic') || id.includes('claude')) {
     return 'anthropic';
   }
diff --git a/packages/kosong/src/index.ts b/packages/kosong/src/index.ts
index cd0440637b..f56dac3c4f 100644
--- a/packages/kosong/src/index.ts
+++ b/packages/kosong/src/index.ts
@@ -27,6 +27,9 @@ export type {
 export * from './provider';
 export { createProvider, getModelCapability } from './providers';
 export type { ProviderConfig, ProviderType } from './providers';
+export { expandHomePath, tryReadProjectIdFromServiceAccount } from './providers/vertex-utils';
+export { GoogleGenAIChatProvider } from './providers/google-genai';
+export { AnthropicChatProvider } from './providers/anthropic';
 // Kimi provider: exported so callers can narrow a `ChatProvider` to the Kimi
 // backend (instanceof) and apply Kimi-specific request params (generation
 // kwargs, `thinking.keep` extra body).
diff --git a/packages/kosong/src/providers/anthropic.ts b/packages/kosong/src/providers/anthropic.ts
index 5af85106e2..6f32768cf0 100644
--- a/packages/kosong/src/providers/anthropic.ts
+++ b/packages/kosong/src/providers/anthropic.ts
@@ -50,6 +50,7 @@ import {
   type AnthropicModelProfile,
   type AnthropicModelVersion,
 } from './anthropic-profile';
+import { GoogleAuth } from 'google-auth-library';
 import { mergeConsecutiveUserMessages } from './merge-user-messages';
 import { mergeRequestHeaders, resolveAuthBackedClient } from './request-auth';
 import {
@@ -57,6 +58,7 @@ import {
   sanitizeToolCallId,
   type ToolCallIdPolicy,
 } from './tool-call-id';
+import { expandHomePath, tryReadProjectIdFromServiceAccount } from './vertex-utils';
 
 /**
  * Normalize an Anthropic `stop_reason` string to the unified
@@ -121,6 +123,11 @@ export interface AnthropicOptions {
    * keeps the standard endpoint + header behavior.
    */
   betaApi?: boolean | undefined;
+  vertexai?: boolean | undefined;
+  project?: string | undefined;
+  location?: string | undefined;
+  serviceAccountFile?: string | undefined;
+  googleAuthOptions?: Record<string, unknown> | undefined;
   clientFactory?: (auth: ProviderRequestAuth) => Anthropic;
   /**
    * Vendor error classification, consulted by `convertAnthropicError` with
@@ -934,6 +941,11 @@ export class AnthropicChatProvider implements ChatProvider {
   private readonly _convertErrorHook: ((error: unknown) => ChatProviderError | undefined) | undefined;
   private _betaApi: boolean;
   private _explicitMaxTokens: boolean;
+  private _vertexai: boolean;
+  private _project: string | undefined;
+  private _location: string | undefined;
+  private _serviceAccountFile: string | undefined;
+  private _googleAuthOptions: Record<string, unknown> | undefined;
 
   constructor(options: AnthropicOptions) {
     this._model = options.model;
@@ -944,12 +956,40 @@ export class AnthropicChatProvider implements ChatProvider {
     this._kimiThinking = options.kimiThinking ?? false;
     this._convertErrorHook = options.convertError;
     this._betaApi = options.betaApi ?? false;
+    this._vertexai = options.vertexai ?? false;
     this._apiKey =
       options.apiKey === undefined || options.apiKey.length === 0 ? undefined : options.apiKey;
     this._baseUrl = options.baseUrl;
     this._defaultHeaders = options.defaultHeaders;
     this._clientFactory = options.clientFactory;
-    this._client = this._apiKey === undefined ? undefined : this._buildClient(this._apiKey);
+
+    const rawSaFile =
+      options.serviceAccountFile ??
+      process.env['GOOGLE_APPLICATION_CREDENTIALS'] ??
+      process.env['SERVICE_ACCOUNT_FILE'];
+    this._serviceAccountFile = expandHomePath(rawSaFile);
+    this._googleAuthOptions =
+      options.googleAuthOptions ??
+      (this._serviceAccountFile !== undefined
+        ? {
+            keyFilename: this._serviceAccountFile,
+            scopes: ['https://www.googleapis.com/auth/cloud-platform'],
+          }
+        : undefined);
+
+    this._project =
+      options.project ??
+      (this._serviceAccountFile !== undefined
+        ? tryReadProjectIdFromServiceAccount(this._serviceAccountFile)
+        : undefined) ??
+      process.env['GOOGLE_CLOUD_PROJECT'];
+    this._location = options.location ?? process.env['GOOGLE_CLOUD_LOCATION'] ?? 'us-central1';
+
+    this._client = this._vertexai
+      ? this._buildVertexClient()
+      : this._apiKey === undefined
+        ? undefined
+        : this._buildClient(this._apiKey);
     this._explicitMaxTokens = options.defaultMaxTokens !== undefined;
     this._generationKwargs = {
       max_tokens: options.defaultMaxTokens ?? resolveDefaultMaxTokens(options.model),
@@ -1157,6 +1197,12 @@ export class AnthropicChatProvider implements ChatProvider {
   }
 
   private _createClient(auth: ProviderRequestAuth | undefined): Anthropic {
+    if (this._vertexai) {
+      if (this._client === undefined) {
+        this._client = this._buildVertexClient();
+      }
+      return this._client;
+    }
     return resolveAuthBackedClient(
       { cachedClient: this._client, clientFactory: this._clientFactory },
       auth,
@@ -1210,6 +1256,127 @@ export class AnthropicChatProvider implements ChatProvider {
   // These `null`s — and the nulled headers in _buildDefaultHeaders — are NOT
   // redundant: removing them reintroduces credential leakage. Regression cover:
   // test/e2e/anthropic-adapter.test.ts.
+  private _buildVertexClient(): Anthropic {
+    const googleAuth = new GoogleAuth(
+      this._googleAuthOptions ?? {
+        scopes: ['https://www.googleapis.com/auth/cloud-platform'],
+      },
+    );
+
+    const project = this._project;
+    const location = this._location ?? 'us-central1';
+    const customBaseUrl = this._baseUrl;
+
+    const vertexFetch = async (
+      url: string | URL | Request,
+      init?: RequestInit,
+    ): Promise<Response> => {
+      const authObj = googleAuth as {
+        getClient(): Promise<{ getAccessToken(): Promise<{ token?: string | null }> }>;
+      };
+      const client = await authObj.getClient();
+      const tokenResponse = await client.getAccessToken();
+      const token = tokenResponse.token;
+
+      let bodyObj: Record<string, unknown> = {};
+      if (init?.body && typeof init.body === 'string') {
+        try {
+          bodyObj = JSON.parse(init.body) as Record<string, unknown>;
+        } catch {
+          bodyObj = {};
+        }
+      }
+
+      const isStream = bodyObj['stream'] === true;
+      const modelName =
+        (typeof bodyObj['model'] === 'string' ? bodyObj['model'] : this._model) || this._model;
+      delete bodyObj['model'];
+      delete bodyObj['stream'];
+      bodyObj['anthropic_version'] = 'vertex-2023-10-16';
+
+      const verb = isStream ? 'streamRawPredict' : 'rawPredict';
+
+      let targetUrl: string;
+      if (customBaseUrl && customBaseUrl.length > 0) {
+        const cleanBase = customBaseUrl.replace(/\/+$/, '');
+        targetUrl = `${cleanBase}/v1/projects/${project}/locations/${location}/publishers/anthropic/models/${modelName}:${verb}`;
+      } else {
+        const host =
+          location === 'global'
+            ? 'aiplatform.googleapis.com'
+            : `${location}-aiplatform.googleapis.com`;
+        targetUrl = `https://${host}/v1/projects/${project}/locations/${location}/publishers/anthropic/models/${modelName}:${verb}`;
+      }
+
+      const headers = new Headers(init?.headers);
+      if (token) {
+        headers.set('Authorization', `Bearer ${token}`);
+      }
+      headers.set('Content-Type', 'application/json');
+
+      const newInit: RequestInit = {
+        ...init,
+        headers,
+        body: JSON.stringify(bodyObj),
+      };
+
+      const res = await fetch(targetUrl, newInit);
+      if (isStream && res.status === 200) {
+        const contentType = res.headers.get('content-type') ?? '';
+        if (!contentType.includes('text/event-stream')) {
+          const json = (await res.json()) as Record<string, unknown>;
+          const content =
+            (json['content'] as Array<{ type: string; text?: string; thinking?: string }>) || [];
+          const sseParts: string[] = [
+            `event: message_start\ndata: ${JSON.stringify({ type: 'message_start', message: json })}\n\n`,
+          ];
+          for (let idx = 0; idx < content.length; idx++) {
+            const c = content[idx]!;
+            if (c.type === 'thinking') {
+              sseParts.push(
+                `event: content_block_start\ndata: ${JSON.stringify({ type: 'content_block_start', index: idx, content_block: { type: 'thinking', thinking: '' } })}\n\n`,
+              );
+              sseParts.push(
+                `event: content_block_delta\ndata: ${JSON.stringify({ type: 'content_block_delta', index: idx, delta: { type: 'thinking_delta', thinking: c.thinking || '' } })}\n\n`,
+              );
+              sseParts.push(
+                `event: content_block_stop\ndata: ${JSON.stringify({ type: 'content_block_stop', index: idx })}\n\n`,
+              );
+            } else {
+              sseParts.push(
+                `event: content_block_start\ndata: ${JSON.stringify({ type: 'content_block_start', index: idx, content_block: { type: 'text', text: '' } })}\n\n`,
+              );
+              sseParts.push(
+                `event: content_block_delta\ndata: ${JSON.stringify({ type: 'content_block_delta', index: idx, delta: { type: 'text_delta', text: c.text || '' } })}\n\n`,
+              );
+              sseParts.push(
+                `event: content_block_stop\ndata: ${JSON.stringify({ type: 'content_block_stop', index: idx })}\n\n`,
+              );
+            }
+          }
+          sseParts.push(
+            `event: message_delta\ndata: ${JSON.stringify({ type: 'message_delta', delta: { stop_reason: json['stop_reason'] || 'end_turn', stop_sequence: json['stop_sequence'] }, usage: json['usage'] })}\n\n`,
+          );
+          sseParts.push(`event: message_stop\ndata: ${JSON.stringify({ type: 'message_stop' })}\n\n`);
+
+          return new Response(sseParts.join(''), {
+            status: 200,
+            headers: { 'Content-Type': 'text/event-stream' },
+          });
+        }
+      }
+      return res;
+    };
+
+    return new Anthropic({
+      apiKey: this._apiKey ?? 'dummy-vertex-key',
+      authToken: null,
+      baseURL: null,
+      fetch: vertexFetch,
+      defaultHeaders: this._buildDefaultHeaders(this._apiKey ?? 'dummy-vertex-key'),
+    });
+  }
+
   private _buildClient(apiKey: string): Anthropic {
     return new Anthropic({
       apiKey,
diff --git a/packages/kosong/src/providers/google-genai.ts b/packages/kosong/src/providers/google-genai.ts
index 5015e0a4b6..59b2162e54 100644
--- a/packages/kosong/src/providers/google-genai.ts
+++ b/packages/kosong/src/providers/google-genai.ts
@@ -19,6 +19,7 @@ import type { Tool } from '#/tool';
 import type { TokenUsage } from '#/usage';
 import { ApiError as GoogleApiError, GoogleGenAI as GenAIClient } from '@google/genai';
 import { mergeConsecutiveUserMessages } from './merge-user-messages';
+import { expandHomePath, tryReadProjectIdFromServiceAccount } from './vertex-utils';
 
 import { requireProviderApiKey, resolveAuthBackedClient } from './request-auth';
 
@@ -88,6 +89,8 @@ export interface GoogleGenAIOptions {
   vertexai?: boolean | undefined;
   project?: string | undefined;
   location?: string | undefined;
+  serviceAccountFile?: string | undefined;
+  googleAuthOptions?: Record<string, unknown> | undefined;
   stream?: boolean | undefined;
   defaultHeaders?: Record<string, string>;
   clientFactory?: (auth: ProviderRequestAuth) => GenAIClient;
@@ -117,16 +120,17 @@ interface GoogleTool {
   functionDeclarations: GoogleFunctionDeclaration[];
 }
 
-function toolToGoogleGenAI(tool: Tool): GoogleTool {
-  return {
-    functionDeclarations: [
-      {
+function toolsToGoogleGenAI(tools: Tool[]): GoogleTool[] {
+  if (tools.length === 0) return [];
+  return [
+    {
+      functionDeclarations: tools.map((tool) => ({
         name: tool.name,
         description: tool.description,
         parametersJsonSchema: tool.parameters,
-      },
-    ],
-  };
+      })),
+    },
+  ];
 }
 
 function applyResponseFormat(
@@ -754,6 +758,8 @@ export class GoogleGenAIChatProvider implements ChatProvider {
   private _baseUrl: string | undefined;
   private _project: string | undefined;
   private _location: string | undefined;
+  private _serviceAccountFile: string | undefined;
+  private _googleAuthOptions: Record<string, unknown> | undefined;
   private _defaultHeaders: Record<string, string> | undefined;
   private _clientFactory: ((auth: ProviderRequestAuth) => GenAIClient) | undefined;
 
@@ -767,12 +773,34 @@ export class GoogleGenAIChatProvider implements ChatProvider {
     this._apiKey = apiKey === undefined || apiKey.length === 0 ? undefined : apiKey;
     this._baseUrl =
       options.baseUrl === undefined || options.baseUrl.length === 0 ? undefined : options.baseUrl;
-    this._project = options.project;
-    this._location = options.location;
+
+    const rawSaFile =
+      options.serviceAccountFile ??
+      process.env['GOOGLE_APPLICATION_CREDENTIALS'] ??
+      process.env['SERVICE_ACCOUNT_FILE'];
+    this._serviceAccountFile = expandHomePath(rawSaFile);
+    this._googleAuthOptions =
+      options.googleAuthOptions ??
+      (this._serviceAccountFile !== undefined
+        ? {
+            keyFilename: this._serviceAccountFile,
+            scopes: ['https://www.googleapis.com/auth/cloud-platform'],
+          }
+        : undefined);
+
+    this._project =
+      options.project ??
+      (this._serviceAccountFile !== undefined
+        ? tryReadProjectIdFromServiceAccount(this._serviceAccountFile)
+        : undefined) ??
+      process.env['GOOGLE_CLOUD_PROJECT'];
+    this._location = options.location ?? process.env['GOOGLE_CLOUD_LOCATION'];
     this._defaultHeaders = options.defaultHeaders;
     this._clientFactory = options.clientFactory;
     this._client =
-      this._vertexai || this._apiKey !== undefined ? this._buildClient(this._apiKey) : undefined;
+      this._vertexai || this._apiKey !== undefined || this._googleAuthOptions !== undefined
+        ? this._buildClient(this._apiKey)
+        : undefined;
   }
 
   private _buildClient(apiKey: string | undefined): GenAIClient {
@@ -796,6 +824,9 @@ export class GoogleGenAIChatProvider implements ChatProvider {
             vertexai: true,
             project: this._project,
             location: this._location,
+            ...(this._googleAuthOptions !== undefined
+              ? { googleAuthOptions: this._googleAuthOptions }
+              : {}),
           }
         : {}),
       ...(Object.keys(httpOptions).length > 0 ? { httpOptions } : {}),
@@ -863,7 +894,7 @@ export class GoogleGenAIChatProvider implements ChatProvider {
     const config: Record<string, unknown> = {
       ...this._generationKwargs,
       systemInstruction: systemPrompt,
-      ...(tools.length > 0 ? { tools: tools.map((t) => toolToGoogleGenAI(t)) } : {}),
+      ...(tools.length > 0 ? { tools: toolsToGoogleGenAI(tools) } : {}),
     };
     applyResponseFormat(config, options?.responseFormat);
 
diff --git a/packages/kosong/src/providers/index.ts b/packages/kosong/src/providers/index.ts
index d95e9c58e9..f7c253f980 100644
--- a/packages/kosong/src/providers/index.ts
+++ b/packages/kosong/src/providers/index.ts
@@ -18,7 +18,9 @@ export type ProviderConfig =
   | ({ type: 'kimi' } & KimiOptions)
   | ({ type: 'google-genai' } & GoogleGenAIOptions)
   | ({ type: 'openai_responses' } & OpenAIResponsesOptions)
-  | ({ type: 'vertexai' } & GoogleGenAIOptions);
+  | ({ type: 'vertexai' } & GoogleGenAIOptions)
+  | ({ type: 'google-vertex' } & GoogleGenAIOptions)
+  | ({ type: 'google-vertex-anthropic' } & AnthropicOptions);
 
 export type ProviderType = ProviderConfig['type'];
 
@@ -36,6 +38,10 @@ export function createProvider(config: ProviderConfig): ChatProvider {
       return new OpenAIResponsesChatProvider(config);
     case 'vertexai':
       return new GoogleGenAIChatProvider(config);
+    case 'google-vertex':
+      return new GoogleGenAIChatProvider({ ...config, vertexai: true });
+    case 'google-vertex-anthropic':
+      return new AnthropicChatProvider({ ...config, vertexai: true });
     default: {
       const exhaustive: never = config;
       throw new Error(`Unknown provider type: ${String(exhaustive)}`);
@@ -61,7 +67,10 @@ export function getModelCapability(wire: ProviderType, modelName: string): Model
       return getOpenAIResponsesModelCapability(modelName);
     case 'google-genai':
     case 'vertexai':
+    case 'google-vertex':
       return getGoogleGenAIModelCapability(modelName);
+    case 'google-vertex-anthropic':
+      return getAnthropicModelCapability(modelName);
     case 'kimi':
       return UNKNOWN_CAPABILITY;
     default: {
diff --git a/packages/kosong/src/providers/vertex-utils.ts b/packages/kosong/src/providers/vertex-utils.ts
new file mode 100644
index 0000000000..1063e94da4
--- /dev/null
+++ b/packages/kosong/src/providers/vertex-utils.ts
@@ -0,0 +1,36 @@
+import { readFileSync } from 'node:fs';
+import { homedir } from 'node:os';
+import { join } from 'node:path';
+
+/**
+ * Expands a leading tilde (`~` or `~/`) in a file path to the user's home directory.
+ */
+export function expandHomePath(filePath: string | undefined): string | undefined {
+  if (filePath === undefined) return undefined;
+  const trimmed = filePath.trim();
+  if (trimmed.length === 0) return undefined;
+  if (trimmed === '~') return homedir();
+  if (trimmed.startsWith('~/') || trimmed.startsWith('~\\')) {
+    return join(homedir(), trimmed.slice(2));
+  }
+  return trimmed;
+}
+
+/**
+ * Safely attempts to read the `project_id` field from a GCP service account JSON file.
+ */
+export function tryReadProjectIdFromServiceAccount(filePath: string | undefined): string | undefined {
+  if (filePath === undefined) return undefined;
+  const expanded = expandHomePath(filePath);
+  if (expanded === undefined) return undefined;
+  try {
+    const content = readFileSync(expanded, 'utf8');
+    const parsed = JSON.parse(content) as Record<string, unknown>;
+    if (typeof parsed['project_id'] === 'string' && parsed['project_id'].length > 0) {
+      return parsed['project_id'];
+    }
+  } catch {
+    // Ignore unreadable file or invalid JSON; SDK auth will handle invalid files
+  }
+  return undefined;
+}
diff --git a/packages/kosong/test/catalog.test.ts b/packages/kosong/test/catalog.test.ts
index ace6298362..301c96669f 100644
--- a/packages/kosong/test/catalog.test.ts
+++ b/packages/kosong/test/catalog.test.ts
@@ -51,7 +51,7 @@ describe('resolveCatalogImport — wire resolution', () => {
     });
     expect(resolveCatalogImport({ id: 'google-vertex' })).toMatchObject({
       kind: 'ok',
-      wire: 'vertexai',
+      wire: 'google-vertex',
     });
   });
 
@@ -125,15 +125,15 @@ describe('resolveCatalogImport — endpoint resolution', () => {
     });
     expect(
       resolveCatalogImport({ id: 'google-vertex', npm: '@ai-sdk/google-vertex' }),
-    ).toMatchObject({ kind: 'ok', wire: 'vertexai' });
+    ).toMatchObject({ kind: 'ok', wire: 'google-vertex' });
   });
 
-  it('needs a URL for non-official vendors without one', () => {
+  it('resolves google-vertex-anthropic without requiring a base URL prompt', () => {
     // google-vertex-anthropic shape: Anthropic wire, vendor npm, no api —
-    // without a prompt the key would be sent to api.anthropic.com.
+    // self-contained via Google Vertex ADC auth.
     expect(
       resolveCatalogImport({ id: 'google-vertex-anthropic', npm: '@ai-sdk/google-vertex/anthropic' }),
-    ).toEqual({ kind: 'needs-base-url', wire: 'anthropic', guessed: false });
+    ).toEqual({ kind: 'ok', wire: 'google-vertex-anthropic', guessed: false });
     // kimi-for-coding declares a concrete api — no prompt needed.
     expect(
       resolveCatalogImport({
@@ -186,9 +186,9 @@ describe('resolveCatalogImport — endpoint resolution', () => {
       ),
     ).toEqual({
       kind: 'ok',
-      wire: 'anthropic',
+      wire: 'google-vertex-anthropic',
       guessed: false,
-      baseUrl: 'https://gateway.example.test',
+      baseUrl: 'https://gateway.example.test/v1',
     });
   });
 
diff --git a/packages/kosong/test/vertex-service-account.test.ts b/packages/kosong/test/vertex-service-account.test.ts
new file mode 100644
index 0000000000..7dda1bb39a
--- /dev/null
+++ b/packages/kosong/test/vertex-service-account.test.ts
@@ -0,0 +1,112 @@
+import { writeFileSync, mkdirSync, rmSync } from 'node:fs';
+import { homedir } from 'node:os';
+import { join } from 'node:path';
+import { describe, expect, it, afterAll, beforeAll } from 'vitest';
+import {
+  createProvider,
+  expandHomePath,
+  tryReadProjectIdFromServiceAccount,
+  GoogleGenAIChatProvider,
+  AnthropicChatProvider,
+} from '../src';
+
+describe('Vertex AI Service Account Support', () => {
+  const tmpDir = join(homedir(), '.test-secrets-tmp');
+  const saFileRel = '~/.test-secrets-tmp/test-sa.json';
+  const saFileAbs = join(tmpDir, 'test-sa.json');
+
+  beforeAll(() => {
+    mkdirSync(tmpDir, { recursive: true });
+    writeFileSync(
+      saFileAbs,
+      JSON.stringify({
+        type: 'service_account',
+        project_id: 'sa-project-123',
+        private_key_id: 'key-id-456',
+        private_key: '-----BEGIN PRIVATE KEY-----\nMIIEvgIBADANBgkqhkiG9w0BAQEFAASCBKgwggSlAgEAAoIBAQC...\n-----END PRIVATE KEY-----\n',
+        client_email: 'test-sa@sa-project-123.iam.gserviceaccount.com',
+      }),
+    );
+  });
+
+  afterAll(() => {
+    try {
+      rmSync(tmpDir, { recursive: true, force: true });
+    } catch {
+      // Ignore
+    }
+  });
+
+  describe('expandHomePath', () => {
+    it('expands ~ to home directory', () => {
+      expect(expandHomePath('~')).toBe(homedir());
+      expect(expandHomePath('~/my-folder/file.json')).toBe(join(homedir(), 'my-folder/file.json'));
+      expect(expandHomePath('~/.secrets/sa.json')).toBe(join(homedir(), '.secrets/sa.json'));
+    });
+
+    it('returns absolute or relative paths unchanged', () => {
+      expect(expandHomePath('/tmp/sa.json')).toBe('/tmp/sa.json');
+      expect(expandHomePath('relative/sa.json')).toBe('relative/sa.json');
+      expect(expandHomePath(undefined)).toBeUndefined();
+      expect(expandHomePath('')).toBeUndefined();
+    });
+  });
+
+  describe('tryReadProjectIdFromServiceAccount', () => {
+    it('reads project_id from tilde-expanded service account path', () => {
+      expect(tryReadProjectIdFromServiceAccount(saFileRel)).toBe('sa-project-123');
+      expect(tryReadProjectIdFromServiceAccount(saFileAbs)).toBe('sa-project-123');
+    });
+
+    it('returns undefined for non-existent file or invalid JSON', () => {
+      expect(tryReadProjectIdFromServiceAccount('/non-existent/file.json')).toBeUndefined();
+      expect(tryReadProjectIdFromServiceAccount(undefined)).toBeUndefined();
+    });
+  });
+
+  describe('google-vertex provider', () => {
+    it('initializes GoogleGenAIChatProvider with serviceAccountFile and reads project_id', () => {
+      const provider = createProvider({
+        type: 'google-vertex',
+        model: 'gemini-2.5-pro',
+        serviceAccountFile: saFileRel,
+        location: 'us-central1',
+      });
+
+      expect(provider).toBeInstanceOf(GoogleGenAIChatProvider);
+      expect(provider.modelName).toBe('gemini-2.5-pro');
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      const pAny = provider as any;
+      expect(pAny._serviceAccountFile).toBe(saFileAbs);
+      expect(pAny._project).toBe('sa-project-123');
+      expect(pAny._googleAuthOptions).toEqual({
+        keyFilename: saFileAbs,
+        scopes: ['https://www.googleapis.com/auth/cloud-platform'],
+      });
+    });
+  });
+
+  describe('google-vertex-anthropic provider', () => {
+    it('initializes AnthropicChatProvider with vertexai and serviceAccountFile', () => {
+      const provider = createProvider({
+        type: 'google-vertex-anthropic',
+        model: 'claude-sonnet-4-6',
+        serviceAccountFile: saFileRel,
+        location: 'us-east5',
+      });
+
+      expect(provider).toBeInstanceOf(AnthropicChatProvider);
+      expect(provider.modelName).toBe('claude-sonnet-4-6');
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      const pAny = provider as any;
+      expect(pAny._vertexai).toBe(true);
+      expect(pAny._serviceAccountFile).toBe(saFileAbs);
+      expect(pAny._project).toBe('sa-project-123');
+      expect(pAny._location).toBe('us-east5');
+      expect(pAny._googleAuthOptions).toEqual({
+        keyFilename: saFileAbs,
+        scopes: ['https://www.googleapis.com/auth/cloud-platform'],
+      });
+    });
+  });
+});
diff --git a/packages/node-sdk/package.json b/packages/node-sdk/package.json
index 2890654a0d..3160f2071e 100644
--- a/packages/node-sdk/package.json
+++ b/packages/node-sdk/package.json
@@ -66,6 +66,7 @@
     "@moonshot-ai/klient": "workspace:^",
     "@moonshot-ai/kosong": "workspace:^",
     "@types/yazl": "^2.4.6",
+    "google-auth-library": "^10.6.2",
     "jimp": "^1.6.1"
   }
 }
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index a29a930cd8..52e56fb07b 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -658,6 +658,9 @@ importers:
       chokidar:
         specifier: ^4.0.3
         version: 4.0.3
+      google-auth-library:
+        specifier: ^10.6.2
+        version: 10.6.2
       ignore:
         specifier: ^5.3.2
         version: 5.3.2
@@ -851,6 +854,9 @@ importers:
       '@google/genai':
         specifier: ^1.49.0
         version: 1.49.0(@modelcontextprotocol/sdk@1.29.0(zod@4.3.6))
+      google-auth-library:
+        specifier: ^10.6.2
+        version: 10.6.2
       openai:
         specifier: ^6.34.0
         version: 6.34.0(ws@8.20.0)(zod@4.3.6)
@@ -922,6 +928,9 @@ importers:
       '@types/yazl':
         specifier: ^2.4.6
         version: 2.4.6
+      google-auth-library:
+        specifier: ^10.6.2
+        version: 10.6.2
       jimp:
         specifier: ^1.6.1
         version: 1.6.1
@@ -13291,7 +13300,7 @@ snapshots:
       obug: 2.1.1
       std-env: 4.0.0
       tinyrainbow: 3.1.0
-      vitest: 4.1.4(@types/node@22.19.17)(@vitest/coverage-v8@4.1.4)(jsdom@25.0.1)(msw@2.15.0(@types/node@22.19.17)(typescript@6.0.2))(vite@8.0.8(@types/node@22.19.17)(esbuild@0.27.7)(jiti@2.6.1)(tsx@4.21.0)(yaml@2.8.3))
+      vitest: 4.1.4(@types/node@22.19.17)(@vitest/coverage-v8@4.1.4)(jsdom@25.0.1)(msw@2.15.0(@types/node@22.19.17)(typescript@6.0.2))(vite@6.4.2(@types/node@22.19.17)(jiti@2.6.1)(lightningcss@1.32.0)(tsx@4.21.0)(yaml@2.8.3))
 
   '@vitest/expect@4.1.4':
     dependencies: