diff --git a/CHANGELOG.md b/CHANGELOG.md
index f24bdb803b2..a7e6e31e10b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,7 @@ Docs: https://docs.openclaw.ai
 - Plugin hooks: expose first-class run, message, sender, session, and trace correlation fields on message hook contexts and run lifecycle events. Thanks @vincentkoc.
 - TUI/dependencies: remove direct `cli-highlight` usage from the OpenClaw TUI code-block renderer, keeping themed code coloring without the extra root dependency. Thanks @vincentkoc.
 - Diagnostics/OTEL: export run, model-call, and tool-execution diagnostic lifecycle events as OTEL spans without retaining live span state. Thanks @vincentkoc.
+- Providers/Anthropic Vertex: move the Vertex SDK runtime behind the bundled provider plugin so core no longer owns that provider-specific dependency. Thanks @vincentkoc.
 - Plugins/activation: expose activation plan reasons and a richer plan API so callers can inspect why a plugin was selected while preserving existing id-list activation behavior. (#70943) Thanks @vincentkoc.
 - Plugins/source metadata: expose normalized install-source facts on provider and channel catalogs so onboarding can explain npm pinning, integrity state, and local availability before runtime loads. (#70951) Thanks @vincentkoc.
 - Plugins/catalog: pin the official external WeCom channel source to an exact npm release plus dist integrity, with a guard that official external sources stay integrity-pinned. (#70997) Thanks @vincentkoc.
diff --git a/extensions/anthropic-vertex/api.test.ts b/extensions/anthropic-vertex/api.test.ts
new file mode 100644
index 00000000000..d177f8833ed
--- /dev/null
+++ b/extensions/anthropic-vertex/api.test.ts
@@ -0,0 +1,77 @@
+import type { Model } from "@mariozechner/pi-ai";
+import { beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
+
+const hoisted = vi.hoisted(() => {
+  const streamAnthropicMock = vi.fn(() => Symbol("anthropic-vertex-stream"));
+  const anthropicVertexCtorMock = vi.fn();
+
+  return {
+    streamAnthropicMock,
+    anthropicVertexCtorMock,
+  };
+});
+
+vi.mock("@mariozechner/pi-ai", async () => {
+  const original =
+    await vi.importActual<typeof import("@mariozechner/pi-ai")>("@mariozechner/pi-ai");
+  return {
+    ...original,
+    streamAnthropic: hoisted.streamAnthropicMock,
+  };
+});
+
+vi.mock("@anthropic-ai/vertex-sdk", () => ({
+  AnthropicVertex: vi.fn(function MockAnthropicVertex(options: unknown) {
+    hoisted.anthropicVertexCtorMock(options);
+    return { options };
+  }),
+}));
+
+let createAnthropicVertexStreamFn: typeof import("./api.js").createAnthropicVertexStreamFn;
+let createAnthropicVertexStreamFnForModel: typeof import("./api.js").createAnthropicVertexStreamFnForModel;
+
+function makeModel(): Model<"anthropic-messages"> {
+  return {
+    id: "claude-sonnet-4-6",
+    api: "anthropic-messages",
+    provider: "anthropic-vertex",
+    maxTokens: 128000,
+  } as Model<"anthropic-messages">;
+}
+
+describe("Anthropic Vertex API stream factories", () => {
+  beforeAll(async () => {
+    ({ createAnthropicVertexStreamFn, createAnthropicVertexStreamFnForModel } =
+      await import("./api.js"));
+  });
+
+  beforeEach(() => {
+    hoisted.streamAnthropicMock.mockClear();
+    hoisted.anthropicVertexCtorMock.mockClear();
+  });
+
+  it("reuses the runtime stream factory across direct stream calls", async () => {
+    const streamFn = createAnthropicVertexStreamFn("vertex-project", "us-east5");
+    const model = makeModel();
+
+    await streamFn(model, { messages: [] }, {});
+    await streamFn(model, { messages: [] }, {});
+
+    expect(hoisted.anthropicVertexCtorMock).toHaveBeenCalledTimes(1);
+    expect(hoisted.streamAnthropicMock).toHaveBeenCalledTimes(2);
+  });
+
+  it("reuses the runtime stream factory across model-derived stream calls", async () => {
+    const streamFn = createAnthropicVertexStreamFnForModel(makeModel(), {
+      ANTHROPIC_VERTEX_PROJECT_ID: "vertex-project",
+      GOOGLE_CLOUD_LOCATION: "us-east5",
+    } as NodeJS.ProcessEnv);
+    const model = makeModel();
+
+    await streamFn(model, { messages: [] }, {});
+    await streamFn(model, { messages: [] }, {});
+
+    expect(hoisted.anthropicVertexCtorMock).toHaveBeenCalledTimes(1);
+    expect(hoisted.streamAnthropicMock).toHaveBeenCalledTimes(2);
+  });
+});
diff --git a/extensions/anthropic-vertex/api.ts b/extensions/anthropic-vertex/api.ts
index 93d04d19d85..e44b82b045a 100644
--- a/extensions/anthropic-vertex/api.ts
+++ b/extensions/anthropic-vertex/api.ts
@@ -1,3 +1,5 @@
+import type { StreamFn } from "@mariozechner/pi-agent-core";
+
 export {
   ANTHROPIC_VERTEX_DEFAULT_MODEL_ID,
   buildAnthropicVertexProvider,
@@ -40,3 +42,30 @@ export function resolveImplicitAnthropicVertexProvider(params?: { env?: NodeJS.P
 
   return buildAnthropicVertexProvider({ env });
 }
+
+export function createAnthropicVertexStreamFn(
+  projectId: string | undefined,
+  region: string,
+  baseURL?: string,
+): StreamFn {
+  const streamFnPromise = import("./stream-runtime.js").then((runtime) =>
+    runtime.createAnthropicVertexStreamFn(projectId, region, baseURL),
+  );
+  return async (model, context, options) => {
+    const streamFn = await streamFnPromise;
+    return streamFn(model, context, options);
+  };
+}
+
+export function createAnthropicVertexStreamFnForModel(
+  model: { baseUrl?: string },
+  env: NodeJS.ProcessEnv = process.env,
+): StreamFn {
+  const streamFnPromise = import("./stream-runtime.js").then((runtime) =>
+    runtime.createAnthropicVertexStreamFnForModel(model, env),
+  );
+  return async (...args) => {
+    const streamFn = await streamFnPromise;
+    return streamFn(...args);
+  };
+}
diff --git a/extensions/anthropic-vertex/package.json b/extensions/anthropic-vertex/package.json
index 1992c452c1f..ae001972279 100644
--- a/extensions/anthropic-vertex/package.json
+++ b/extensions/anthropic-vertex/package.json
@@ -4,10 +4,18 @@
   "private": true,
   "description": "OpenClaw Anthropic Vertex provider plugin",
   "type": "module",
+  "dependencies": {
+    "@anthropic-ai/vertex-sdk": "^0.16.0",
+    "@mariozechner/pi-agent-core": "0.70.2",
+    "@mariozechner/pi-ai": "0.70.2"
+  },
   "devDependencies": {
     "@openclaw/plugin-sdk": "workspace:*"
   },
   "openclaw": {
+    "bundle": {
+      "stageRuntimeDependencies": true
+    },
     "extensions": [
       "./index.ts"
     ]
diff --git a/src/agents/anthropic-vertex-stream.test.ts b/extensions/anthropic-vertex/stream-runtime.test.ts
similarity index 89%
rename from src/agents/anthropic-vertex-stream.test.ts
rename to extensions/anthropic-vertex/stream-runtime.test.ts
index ef10048cf9a..bddf6e4ccf4 100644
--- a/src/agents/anthropic-vertex-stream.test.ts
+++ b/extensions/anthropic-vertex/stream-runtime.test.ts
@@ -1,6 +1,7 @@
 import type { Model } from "@mariozechner/pi-ai";
 import { beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
-import { SYSTEM_PROMPT_CACHE_BOUNDARY } from "./system-prompt-cache-boundary.js";
+
+const SYSTEM_PROMPT_CACHE_BOUNDARY = "\n<!-- OPENCLAW_CACHE_BOUNDARY -->\n";
 
 const hoisted = vi.hoisted(() => {
   const streamAnthropicMock = vi.fn<(model: unknown, context: unknown, options: unknown) => symbol>(
@@ -31,28 +32,8 @@ vi.mock("@anthropic-ai/vertex-sdk", () => ({
   }),
 }));
 
-vi.mock("../plugin-sdk/anthropic-vertex.js", () => ({
-  resolveAnthropicVertexProjectId: (env: NodeJS.ProcessEnv = process.env) =>
-    env.ANTHROPIC_VERTEX_PROJECT_ID || env.GOOGLE_CLOUD_PROJECT || env.GOOGLE_CLOUD_PROJECT_ID,
-  resolveAnthropicVertexClientRegion: (params?: { baseUrl?: string; env?: NodeJS.ProcessEnv }) => {
-    const baseUrl = params?.baseUrl?.trim();
-    if (baseUrl) {
-      try {
-        const host = new URL(baseUrl).hostname;
-        const match = /^([a-z0-9-]+)-aiplatform\.googleapis\.com$/u.exec(host);
-        if (match?.[1]) {
-          return match[1];
-        }
-      } catch {
-        // noop; test seam only
-      }
-    }
-    return params?.env?.GOOGLE_CLOUD_LOCATION || params?.env?.CLOUD_ML_REGION || "global";
-  },
-}));
-
-let createAnthropicVertexStreamFn: typeof import("./anthropic-vertex-stream.js").createAnthropicVertexStreamFn;
-let createAnthropicVertexStreamFnForModel: typeof import("./anthropic-vertex-stream.js").createAnthropicVertexStreamFnForModel;
+let createAnthropicVertexStreamFn: typeof import("./stream-runtime.js").createAnthropicVertexStreamFn;
+let createAnthropicVertexStreamFnForModel: typeof import("./stream-runtime.js").createAnthropicVertexStreamFnForModel;
 
 function makeModel(params: { id: string; maxTokens?: number }): Model<"anthropic-messages"> {
   return {
@@ -121,7 +102,7 @@ function buildExpectedCacheBoundaryPayload(messageText: string) {
 describe("createAnthropicVertexStreamFn", () => {
   beforeAll(async () => {
     ({ createAnthropicVertexStreamFn, createAnthropicVertexStreamFnForModel } =
-      await import("./anthropic-vertex-stream.js"));
+      await import("./stream-runtime.js"));
   });
 
   beforeEach(() => {
diff --git a/extensions/anthropic-vertex/stream-runtime.ts b/extensions/anthropic-vertex/stream-runtime.ts
new file mode 100644
index 00000000000..f399cc35ae1
--- /dev/null
+++ b/extensions/anthropic-vertex/stream-runtime.ts
@@ -0,0 +1,199 @@
+import { AnthropicVertex } from "@anthropic-ai/vertex-sdk";
+import type { StreamFn } from "@mariozechner/pi-agent-core";
+import { streamAnthropic, type AnthropicOptions, type Model } from "@mariozechner/pi-ai";
+import {
+  applyAnthropicPayloadPolicyToParams,
+  resolveAnthropicPayloadPolicy,
+} from "openclaw/plugin-sdk/provider-stream-shared";
+import { resolveAnthropicVertexClientRegion, resolveAnthropicVertexProjectId } from "./region.js";
+
+type AnthropicVertexEffort = NonNullable<AnthropicOptions["effort"]>;
+type AnthropicVertexAdaptiveEffort = AnthropicVertexEffort | "xhigh";
+
+function isClaudeOpus47Model(modelId: string): boolean {
+  return modelId.includes("opus-4-7") || modelId.includes("opus-4.7");
+}
+
+function isClaudeOpus46Model(modelId: string): boolean {
+  return modelId.includes("opus-4-6") || modelId.includes("opus-4.6");
+}
+
+function supportsAdaptiveThinking(modelId: string): boolean {
+  return (
+    isClaudeOpus47Model(modelId) ||
+    isClaudeOpus46Model(modelId) ||
+    modelId.includes("sonnet-4-6") ||
+    modelId.includes("sonnet-4.6")
+  );
+}
+
+function mapAnthropicAdaptiveEffort(
+  reasoning: string,
+  modelId: string,
+): AnthropicVertexAdaptiveEffort {
+  const effortMap: Record<string, AnthropicVertexAdaptiveEffort> = {
+    minimal: "low",
+    low: "low",
+    medium: "medium",
+    high: "high",
+    xhigh: isClaudeOpus47Model(modelId) ? "xhigh" : isClaudeOpus46Model(modelId) ? "max" : "high",
+  };
+  return effortMap[reasoning] ?? "high";
+}
+
+function resolveAnthropicVertexMaxTokens(params: {
+  modelMaxTokens: number | undefined;
+  requestedMaxTokens: number | undefined;
+}): number | undefined {
+  const modelMax =
+    typeof params.modelMaxTokens === "number" &&
+    Number.isFinite(params.modelMaxTokens) &&
+    params.modelMaxTokens > 0
+      ? Math.floor(params.modelMaxTokens)
+      : undefined;
+  const requested =
+    typeof params.requestedMaxTokens === "number" &&
+    Number.isFinite(params.requestedMaxTokens) &&
+    params.requestedMaxTokens > 0
+      ? Math.floor(params.requestedMaxTokens)
+      : undefined;
+
+  if (modelMax !== undefined && requested !== undefined) {
+    return Math.min(requested, modelMax);
+  }
+  return requested ?? modelMax;
+}
+
+function createAnthropicVertexOnPayload(params: {
+  model: { api: string; baseUrl?: string; provider: string };
+  cacheRetention: AnthropicOptions["cacheRetention"] | undefined;
+  onPayload: AnthropicOptions["onPayload"] | undefined;
+}): NonNullable<AnthropicOptions["onPayload"]> {
+  const policy = resolveAnthropicPayloadPolicy({
+    provider: params.model.provider,
+    api: params.model.api,
+    baseUrl: params.model.baseUrl,
+    cacheRetention: params.cacheRetention,
+    enableCacheControl: true,
+  });
+
+  function applyPolicy(payload: unknown): unknown {
+    if (payload && typeof payload === "object" && !Array.isArray(payload)) {
+      applyAnthropicPayloadPolicyToParams(payload as Record<string, unknown>, policy);
+    }
+    return payload;
+  }
+
+  return async (payload, model) => {
+    const shapedPayload = applyPolicy(payload);
+    const nextPayload = await params.onPayload?.(shapedPayload, model);
+    if (nextPayload === undefined || nextPayload === shapedPayload) {
+      return shapedPayload;
+    }
+    return applyPolicy(nextPayload);
+  };
+}
+
+/**
+ * Create a StreamFn that routes through pi-ai's `streamAnthropic` with an
+ * injected `AnthropicVertex` client.  All streaming, message conversion, and
+ * event handling is handled by pi-ai — we only supply the GCP-authenticated
+ * client and map SimpleStreamOptions → AnthropicOptions.
+ */
+export function createAnthropicVertexStreamFn(
+  projectId: string | undefined,
+  region: string,
+  baseURL?: string,
+): StreamFn {
+  const client = new AnthropicVertex({
+    region,
+    ...(baseURL ? { baseURL } : {}),
+    ...(projectId ? { projectId } : {}),
+  });
+
+  return (model, context, options) => {
+    const transportModel = model as Model<"anthropic-messages"> & {
+      api: string;
+      baseUrl?: string;
+      provider: string;
+    };
+    const maxTokens = resolveAnthropicVertexMaxTokens({
+      modelMaxTokens: transportModel.maxTokens,
+      requestedMaxTokens: options?.maxTokens,
+    });
+    const opts: AnthropicOptions = {
+      client: client as unknown as AnthropicOptions["client"],
+      temperature: options?.temperature,
+      ...(maxTokens !== undefined ? { maxTokens } : {}),
+      signal: options?.signal,
+      cacheRetention: options?.cacheRetention,
+      sessionId: options?.sessionId,
+      headers: options?.headers,
+      onPayload: createAnthropicVertexOnPayload({
+        model: transportModel,
+        cacheRetention: options?.cacheRetention,
+        onPayload: options?.onPayload,
+      }),
+      maxRetryDelayMs: options?.maxRetryDelayMs,
+      metadata: options?.metadata,
+    };
+
+    if (options?.reasoning) {
+      if (supportsAdaptiveThinking(model.id)) {
+        opts.thinkingEnabled = true;
+        opts.effort = mapAnthropicAdaptiveEffort(
+          options.reasoning,
+          model.id,
+        ) as AnthropicVertexEffort;
+      } else {
+        opts.thinkingEnabled = true;
+        const budgets = options.thinkingBudgets;
+        opts.thinkingBudgetTokens =
+          (budgets && options.reasoning in budgets
+            ? budgets[options.reasoning as keyof typeof budgets]
+            : undefined) ?? 10000;
+      }
+    } else {
+      opts.thinkingEnabled = false;
+    }
+
+    return streamAnthropic(transportModel, context, opts);
+  };
+}
+
+function resolveAnthropicVertexSdkBaseUrl(baseUrl?: string): string | undefined {
+  const trimmed = baseUrl?.trim();
+  if (!trimmed) {
+    return undefined;
+  }
+
+  try {
+    const url = new URL(trimmed);
+    const normalizedPath = url.pathname.replace(/\/+$/, "");
+    if (!normalizedPath || normalizedPath === "") {
+      url.pathname = "/v1";
+      return url.toString().replace(/\/$/, "");
+    }
+    if (!normalizedPath.endsWith("/v1")) {
+      url.pathname = `${normalizedPath}/v1`;
+      return url.toString().replace(/\/$/, "");
+    }
+    return trimmed;
+  } catch {
+    return trimmed;
+  }
+}
+
+export function createAnthropicVertexStreamFnForModel(
+  model: { baseUrl?: string },
+  env: NodeJS.ProcessEnv = process.env,
+): StreamFn {
+  return createAnthropicVertexStreamFn(
+    resolveAnthropicVertexProjectId(env),
+    resolveAnthropicVertexClientRegion({
+      baseUrl: model.baseUrl,
+      env,
+    }),
+    resolveAnthropicVertexSdkBaseUrl(model.baseUrl),
+  );
+}
diff --git a/package.json b/package.json
index 56cf2633643..96457d25948 100644
--- a/package.json
+++ b/package.json
@@ -1581,7 +1581,6 @@
   },
   "dependencies": {
     "@agentclientprotocol/sdk": "0.19.1",
-    "@anthropic-ai/vertex-sdk": "^0.16.0",
     "@clack/prompts": "^1.2.0",
     "@lydell/node-pty": "1.2.0-beta.12",
     "@mariozechner/pi-agent-core": "0.70.2",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 962e5a01238..bbac03c1ad7 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -42,9 +42,6 @@ importers:
       '@agentclientprotocol/sdk':
         specifier: 0.19.1
         version: 0.19.1(zod@4.3.6)
-      '@anthropic-ai/vertex-sdk':
-        specifier: ^0.16.0
-        version: 0.16.0(zod@4.3.6)
       '@clack/prompts':
         specifier: ^1.2.0
         version: 1.2.0
@@ -292,6 +289,16 @@ importers:
         version: link:../../packages/plugin-sdk
 
   extensions/anthropic-vertex:
+    dependencies:
+      '@anthropic-ai/vertex-sdk':
+        specifier: ^0.16.0
+        version: 0.16.0(zod@4.3.6)
+      '@mariozechner/pi-agent-core':
+        specifier: 0.70.2
+        version: 0.70.2(@modelcontextprotocol/sdk@1.29.0(zod@4.3.6))(ws@8.20.0)(zod@4.3.6)
+      '@mariozechner/pi-ai':
+        specifier: 0.70.2
+        version: 0.70.2(@modelcontextprotocol/sdk@1.29.0(zod@4.3.6))(ws@8.20.0)(zod@4.3.6)
     devDependencies:
       '@openclaw/plugin-sdk':
         specifier: workspace:*
diff --git a/scripts/lib/dependency-ownership.json b/scripts/lib/dependency-ownership.json
index fda625ed3c6..b214762ccff 100644
--- a/scripts/lib/dependency-ownership.json
+++ b/scripts/lib/dependency-ownership.json
@@ -6,11 +6,6 @@
       "class": "core-runtime",
       "risk": ["protocol-client"]
     },
-    "@anthropic-ai/vertex-sdk": {
-      "owner": "provider:anthropic-vertex",
-      "class": "default-runtime-initially",
-      "risk": ["provider-sdk"]
-    },
     "@clack/prompts": {
       "owner": "core:cli",
       "class": "core-runtime",
diff --git a/src/agents/anthropic-vertex-stream.ts b/src/agents/anthropic-vertex-stream.ts
index 534ab8fca9d..a9e616c97d8 100644
--- a/src/agents/anthropic-vertex-stream.ts
+++ b/src/agents/anthropic-vertex-stream.ts
@@ -1,202 +1,40 @@
-import { AnthropicVertex } from "@anthropic-ai/vertex-sdk";
 import type { StreamFn } from "@mariozechner/pi-agent-core";
-import { streamAnthropic, type AnthropicOptions, type Model } from "@mariozechner/pi-ai";
-import {
-  resolveAnthropicVertexClientRegion,
-  resolveAnthropicVertexProjectId,
-} from "../plugin-sdk/anthropic-vertex.js";
-import {
-  applyAnthropicPayloadPolicyToParams,
-  resolveAnthropicPayloadPolicy,
-} from "./anthropic-payload-policy.js";
+import { loadBundledPluginPublicSurfaceModuleSync } from "../plugin-sdk/facade-loader.js";
 
-type AnthropicVertexEffort = NonNullable<AnthropicOptions["effort"]>;
-type AnthropicVertexAdaptiveEffort = AnthropicVertexEffort | "xhigh";
+type AnthropicVertexStreamFacade = {
+  createAnthropicVertexStreamFn: (
+    projectId: string | undefined,
+    region: string,
+    baseURL?: string,
+  ) => StreamFn;
+  createAnthropicVertexStreamFnForModel: (
+    model: { baseUrl?: string },
+    env?: NodeJS.ProcessEnv,
+  ) => StreamFn;
+};
 
-function isClaudeOpus47Model(modelId: string): boolean {
-  return modelId.includes("opus-4-7") || modelId.includes("opus-4.7");
-}
-
-function isClaudeOpus46Model(modelId: string): boolean {
-  return modelId.includes("opus-4-6") || modelId.includes("opus-4.6");
-}
-
-function supportsAdaptiveThinking(modelId: string): boolean {
-  return (
-    isClaudeOpus47Model(modelId) ||
-    isClaudeOpus46Model(modelId) ||
-    modelId.includes("sonnet-4-6") ||
-    modelId.includes("sonnet-4.6")
-  );
-}
-
-function mapAnthropicAdaptiveEffort(
-  reasoning: string,
-  modelId: string,
-): AnthropicVertexAdaptiveEffort {
-  const effortMap: Record<string, AnthropicVertexAdaptiveEffort> = {
-    minimal: "low",
-    low: "low",
-    medium: "medium",
-    high: "high",
-    xhigh: isClaudeOpus47Model(modelId) ? "xhigh" : isClaudeOpus46Model(modelId) ? "max" : "high",
-  };
-  return effortMap[reasoning] ?? "high";
-}
-
-function resolveAnthropicVertexMaxTokens(params: {
-  modelMaxTokens: number | undefined;
-  requestedMaxTokens: number | undefined;
-}): number | undefined {
-  const modelMax =
-    typeof params.modelMaxTokens === "number" &&
-    Number.isFinite(params.modelMaxTokens) &&
-    params.modelMaxTokens > 0
-      ? Math.floor(params.modelMaxTokens)
-      : undefined;
-  const requested =
-    typeof params.requestedMaxTokens === "number" &&
-    Number.isFinite(params.requestedMaxTokens) &&
-    params.requestedMaxTokens > 0
-      ? Math.floor(params.requestedMaxTokens)
-      : undefined;
-
-  if (modelMax !== undefined && requested !== undefined) {
-    return Math.min(requested, modelMax);
-  }
-  return requested ?? modelMax;
-}
-
-function createAnthropicVertexOnPayload(params: {
-  model: { api: string; baseUrl?: string; provider: string };
-  cacheRetention: AnthropicOptions["cacheRetention"] | undefined;
-  onPayload: AnthropicOptions["onPayload"] | undefined;
-}): NonNullable<AnthropicOptions["onPayload"]> {
-  const policy = resolveAnthropicPayloadPolicy({
-    provider: params.model.provider,
-    api: params.model.api,
-    baseUrl: params.model.baseUrl,
-    cacheRetention: params.cacheRetention,
-    enableCacheControl: true,
+function loadAnthropicVertexStreamFacade(): AnthropicVertexStreamFacade {
+  return loadBundledPluginPublicSurfaceModuleSync<AnthropicVertexStreamFacade>({
+    dirName: "anthropic-vertex",
+    artifactBasename: "api.js",
   });
-
-  function applyPolicy(payload: unknown): unknown {
-    if (payload && typeof payload === "object" && !Array.isArray(payload)) {
-      applyAnthropicPayloadPolicyToParams(payload as Record<string, unknown>, policy);
-    }
-    return payload;
-  }
-
-  return async (payload, model) => {
-    const shapedPayload = applyPolicy(payload);
-    const nextPayload = await params.onPayload?.(shapedPayload, model);
-    if (nextPayload === undefined || nextPayload === shapedPayload) {
-      return shapedPayload;
-    }
-    return applyPolicy(nextPayload);
-  };
 }
 
-/**
- * Create a StreamFn that routes through pi-ai's `streamAnthropic` with an
- * injected `AnthropicVertex` client.  All streaming, message conversion, and
- * event handling is handled by pi-ai — we only supply the GCP-authenticated
- * client and map SimpleStreamOptions → AnthropicOptions.
- */
 export function createAnthropicVertexStreamFn(
   projectId: string | undefined,
   region: string,
   baseURL?: string,
 ): StreamFn {
-  const client = new AnthropicVertex({
+  return loadAnthropicVertexStreamFacade().createAnthropicVertexStreamFn(
+    projectId,
     region,
-    ...(baseURL ? { baseURL } : {}),
-    ...(projectId ? { projectId } : {}),
-  });
-
-  return (model, context, options) => {
-    const transportModel = model as Model<"anthropic-messages"> & {
-      api: string;
-      baseUrl?: string;
-      provider: string;
-    };
-    const maxTokens = resolveAnthropicVertexMaxTokens({
-      modelMaxTokens: transportModel.maxTokens,
-      requestedMaxTokens: options?.maxTokens,
-    });
-    const opts: AnthropicOptions = {
-      client: client as unknown as AnthropicOptions["client"],
-      temperature: options?.temperature,
-      ...(maxTokens !== undefined ? { maxTokens } : {}),
-      signal: options?.signal,
-      cacheRetention: options?.cacheRetention,
-      sessionId: options?.sessionId,
-      headers: options?.headers,
-      onPayload: createAnthropicVertexOnPayload({
-        model: transportModel,
-        cacheRetention: options?.cacheRetention,
-        onPayload: options?.onPayload,
-      }),
-      maxRetryDelayMs: options?.maxRetryDelayMs,
-      metadata: options?.metadata,
-    };
-
-    if (options?.reasoning) {
-      if (supportsAdaptiveThinking(model.id)) {
-        opts.thinkingEnabled = true;
-        opts.effort = mapAnthropicAdaptiveEffort(
-          options.reasoning,
-          model.id,
-        ) as AnthropicVertexEffort;
-      } else {
-        opts.thinkingEnabled = true;
-        const budgets = options.thinkingBudgets;
-        opts.thinkingBudgetTokens =
-          (budgets && options.reasoning in budgets
-            ? budgets[options.reasoning as keyof typeof budgets]
-            : undefined) ?? 10000;
-      }
-    } else {
-      opts.thinkingEnabled = false;
-    }
-
-    return streamAnthropic(transportModel, context, opts);
-  };
-}
-
-function resolveAnthropicVertexSdkBaseUrl(baseUrl?: string): string | undefined {
-  const trimmed = baseUrl?.trim();
-  if (!trimmed) {
-    return undefined;
-  }
-
-  try {
-    const url = new URL(trimmed);
-    const normalizedPath = url.pathname.replace(/\/+$/, "");
-    if (!normalizedPath || normalizedPath === "") {
-      url.pathname = "/v1";
-      return url.toString().replace(/\/$/, "");
-    }
-    if (!normalizedPath.endsWith("/v1")) {
-      url.pathname = `${normalizedPath}/v1`;
-      return url.toString().replace(/\/$/, "");
-    }
-    return trimmed;
-  } catch {
-    return trimmed;
-  }
+    baseURL,
+  );
 }
 
 export function createAnthropicVertexStreamFnForModel(
   model: { baseUrl?: string },
   env: NodeJS.ProcessEnv = process.env,
 ): StreamFn {
-  return createAnthropicVertexStreamFn(
-    resolveAnthropicVertexProjectId(env),
-    resolveAnthropicVertexClientRegion({
-      baseUrl: model.baseUrl,
-      env,
-    }),
-    resolveAnthropicVertexSdkBaseUrl(model.baseUrl),
-  );
+  return loadAnthropicVertexStreamFacade().createAnthropicVertexStreamFnForModel(model, env);
 }