fix: google-vertex support multi-region endpoints

packages/ai/src/providers/google-vertex.ts

@@ -1,4 +1,5 @@
 import { $env } from "@oh-my-pi/pi-utils";
+import { resolveVertexEndpointHost } from "@oh-my-pi/pi-catalog/hosts";
 import * as AIError from "../error";
 import type { Context, Model, StreamFunction } from "../types";
 import type { AssistantMessageEventStream } from "../utils/event-stream";
@@ -69,7 +70,7 @@ export const streamGoogleVertex: StreamFunction<"google-vertex"> = (
 				// global-only request.
 				const explicitLocation = options?.location;
 				const location = explicitLocation ?? resolveAmbientLocation() ?? "global";
-				const host = resolveEndpointHost(location);
+				const host = resolveVertexEndpointHost(location);
 				const path = `${API_VERSION}/publishers/google/models/${model.id}:streamGenerateContent?alt=sse`;
 				const useGlobalFallback = !explicitLocation && host !== "aiplatform.googleapis.com";
 				return {
@@ -87,7 +88,7 @@ export const streamGoogleVertex: StreamFunction<"google-vertex"> = (
 			const project = resolveProject(options);
 			const location = resolveLocation(options);
 			const accessToken = await getVertexAccessToken({ signal: options?.signal, fetch: options?.fetch });
-			const host = resolveEndpointHost(location);
+			const host = resolveVertexEndpointHost(location);
 			const url = `https://${host}/${API_VERSION}/projects/${project}/locations/${location}/publishers/google/models/${model.id}:streamGenerateContent?alt=sse`;
 			return {
 				params,
@@ -117,9 +118,6 @@ function resolveProject(options?: GoogleVertexOptions): string {
 	return project;
 }
 
-function resolveEndpointHost(location: string): string {
-	return location === "global" ? "aiplatform.googleapis.com" : `${location}-aiplatform.googleapis.com`;
-}
 function resolveAmbientLocation(): string | undefined {
 	return $env.GOOGLE_VERTEX_LOCATION || $env.GOOGLE_CLOUD_LOCATION || $env.VERTEX_LOCATION || undefined;
 }

packages/ai/src/stream.ts

@@ -5,7 +5,7 @@ import * as path from "node:path";
 import { scheduler } from "node:timers/promises";
 import { isOfficialAnthropicApiUrl } from "@oh-my-pi/pi-catalog/compat/anthropic";
 import type { Effort } from "@oh-my-pi/pi-catalog/effort";
-import { isVertexExpressOpenAIUrl, isVertexRawPredictUrl } from "@oh-my-pi/pi-catalog/hosts";
+import { isVertexExpressOpenAIUrl, isVertexRawPredictUrl, resolveVertexEndpointHost } from "@oh-my-pi/pi-catalog/hosts";
 import {
 	mapEffortToAnthropicAdaptiveEffort,
 	mapEffortToGoogleThinkingLevel,
@@ -662,7 +662,7 @@ function resolveVertexRequest(input: string | URL | Request): string | URL | Req
 			url.includes("{location}") ||
 			url.includes("%7Bproject%7D") ||
 			url.includes("%7Blocation%7D");
-		const host = location === "global" ? "aiplatform.googleapis.com" : `${location}-aiplatform.googleapis.com`;
+		const host = resolveVertexEndpointHost(location);
 		const rewritten = hasPlaceholder
 			? url
 					.replace("https://{location}-aiplatform.googleapis.com", `https://${host}`)

packages/ai/test/issue-1270-repro.test.ts

@@ -62,4 +62,42 @@ describe("issue #1270: Vertex AI global endpoint", () => {
 			"https://aiplatform.googleapis.com/v1/projects/vertex-project/locations/global/publishers/google/models/gemini-3.1-pro-preview:streamGenerateContent?alt=sse",
 		);
 	});
+
+	it.each([
+		{
+			location: "eu",
+			host: "aiplatform.eu.rep.googleapis.com",
+		},
+		{
+			location: "us",
+			host: "aiplatform.us.rep.googleapis.com",
+		},
+		{
+			location: "europe-west4",
+			host: "europe-west4-aiplatform.googleapis.com",
+		},
+	] as const)("uses the $host host for location $location", async ({ location, host }) => {
+		delete Bun.env.GOOGLE_CLOUD_API_KEY;
+		delete Bun.env.GOOGLE_APPLICATION_CREDENTIALS;
+
+		const urls: string[] = [];
+		const stream = streamGoogleVertex(model, context, {
+			project: "vertex-project",
+			location,
+			fetch: async input => {
+				const url = input instanceof Request ? input.url : input.toString();
+				urls.push(url);
+				if (url === METADATA_TOKEN_URL || url === OAUTH_TOKEN_URL) {
+					return new Response(JSON.stringify({ access_token: "token", expires_in: 3600 }));
+				}
+				return new Response('{"error":{"message":"stop after capture"}}', { status: 400 });
+			},
+		});
+
+		await stream.result();
+
+		expect(urls).toContain(
+			`https://${host}/v1/projects/vertex-project/locations/${location}/publishers/google/models/gemini-3.1-pro-preview:streamGenerateContent?alt=sse`,
+		);
+	});
 });

packages/catalog/src/hosts.ts

@@ -111,6 +111,24 @@ function includesAsciiCaseInsensitive(value: string, lowerNeedle: string): boole
 
 // --- Endpoint-shape predicates (URL path/verb shapes, not vendor hosts) ---
 
+/**
+ * Hostname for a Vertex AI GenerateContent / rawPredict / OpenAI-compat
+ * request for the given location.
+ *
+ * - `global` → global endpoint (`aiplatform.googleapis.com`)
+ * - `eu` / `us` multi-regions → REP endpoints (`aiplatform.{eu|us}.rep.googleapis.com`)
+ * - every other location → regional (`{location}-aiplatform.googleapis.com`)
+ *
+ * Multi-region codes do NOT follow the regional `{location}-aiplatform` pattern;
+ * interpolating them that way yields hosts like `eu-aiplatform.googleapis.com`
+ * that 404.
+ */
+export function resolveVertexEndpointHost(location: string): string {
+	if (location === "global") return "aiplatform.googleapis.com";
+	if (location === "eu" || location === "us") return `aiplatform.${location}.rep.googleapis.com`;
+	return `${location}-aiplatform.googleapis.com`;
+}
+
 /** Vertex AI express-mode OpenAI-compatible endpoint (`…/endpoints/openapi`). */
 export function isVertexExpressOpenAIUrl(baseUrl: string): boolean {
 	return baseUrl.includes("/endpoints/openapi");

packages/catalog/test/hosts.test.ts

@@ -5,6 +5,7 @@ import {
 	isVertexExpressOpenAIUrl,
 	isVertexRawPredictUrl,
 	modelMatchesHost,
+	resolveVertexEndpointHost,
 } from "@oh-my-pi/pi-catalog/hosts";
 
 describe("hostMatchesUrl", () => {
@@ -66,6 +67,14 @@ describe("endpoint shape predicates", () => {
 		).toBe(true);
 	});
 
+	test("resolves Vertex endpoint hosts for global, multi-region, and regional locations", () => {
+		expect(resolveVertexEndpointHost("global")).toBe("aiplatform.googleapis.com");
+		expect(resolveVertexEndpointHost("eu")).toBe("aiplatform.eu.rep.googleapis.com");
+		expect(resolveVertexEndpointHost("us")).toBe("aiplatform.us.rep.googleapis.com");
+		expect(resolveVertexEndpointHost("europe-west4")).toBe("europe-west4-aiplatform.googleapis.com");
+		expect(resolveVertexEndpointHost("us-central1")).toBe("us-central1-aiplatform.googleapis.com");
+	});
+
 	test("requires all DashScope compatible-mode URL markers", () => {
 		expect(isDashscopeCompatibleModeUrl("https://dashscope.aliyuncs.com/compatible-mode/v1")).toBe(true);
 		expect(isDashscopeCompatibleModeUrl("https://example.aliyuncs.com/compatible-mode/v1")).toBe(false);