fix(amazon-bedrock): restore regional endpoint resolution

closes #3481
closes #3485
closes #3486
closes #3487
closes #3488

packages/ai/test/bedrock-endpoint-resolution.test.ts

@@ -0,0 +1,131 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+const bedrockMock = vi.hoisted(() => ({
+	constructorCalls: [] as Array<Record<string, unknown>>,
+}));
+
+vi.mock("@aws-sdk/client-bedrock-runtime", () => {
+	class BedrockRuntimeServiceException extends Error {}
+
+	class BedrockRuntimeClient {
+		constructor(config: Record<string, unknown>) {
+			bedrockMock.constructorCalls.push(config);
+		}
+
+		send(): Promise<never> {
+			return Promise.reject(new Error("mock send"));
+		}
+	}
+
+	class ConverseStreamCommand {
+		readonly input: unknown;
+
+		constructor(input: unknown) {
+			this.input = input;
+		}
+	}
+
+	return {
+		BedrockRuntimeClient,
+		BedrockRuntimeServiceException,
+		ConverseStreamCommand,
+		StopReason: {
+			END_TURN: "end_turn",
+			STOP_SEQUENCE: "stop_sequence",
+			MAX_TOKENS: "max_tokens",
+			MODEL_CONTEXT_WINDOW_EXCEEDED: "model_context_window_exceeded",
+			TOOL_USE: "tool_use",
+		},
+		CachePointType: { DEFAULT: "default" },
+		CacheTTL: { ONE_HOUR: "ONE_HOUR" },
+		ConversationRole: { ASSISTANT: "assistant", USER: "user" },
+		ImageFormat: { JPEG: "jpeg", PNG: "png", GIF: "gif", WEBP: "webp" },
+		ToolResultStatus: { ERROR: "error", SUCCESS: "success" },
+	};
+});
+
+import { getModel } from "../src/models.js";
+import { streamBedrock } from "../src/providers/amazon-bedrock.js";
+import type { Context, Model } from "../src/types.js";
+
+const context: Context = {
+	messages: [{ role: "user", content: "hello", timestamp: Date.now() }],
+};
+
+const originalAwsRegion = process.env.AWS_REGION;
+const originalAwsDefaultRegion = process.env.AWS_DEFAULT_REGION;
+const originalAwsProfile = process.env.AWS_PROFILE;
+
+beforeEach(() => {
+	bedrockMock.constructorCalls.length = 0;
+	delete process.env.AWS_REGION;
+	delete process.env.AWS_DEFAULT_REGION;
+	delete process.env.AWS_PROFILE;
+});
+
+afterEach(() => {
+	if (originalAwsRegion === undefined) {
+		delete process.env.AWS_REGION;
+	} else {
+		process.env.AWS_REGION = originalAwsRegion;
+	}
+
+	if (originalAwsDefaultRegion === undefined) {
+		delete process.env.AWS_DEFAULT_REGION;
+	} else {
+		process.env.AWS_DEFAULT_REGION = originalAwsDefaultRegion;
+	}
+
+	if (originalAwsProfile === undefined) {
+		delete process.env.AWS_PROFILE;
+	} else {
+		process.env.AWS_PROFILE = originalAwsProfile;
+	}
+});
+
+async function captureClientConfig(model: Model<"bedrock-converse-stream">): Promise<Record<string, unknown>> {
+	await streamBedrock(model, context, { cacheRetention: "none" }).result();
+	expect(bedrockMock.constructorCalls).toHaveLength(1);
+	return bedrockMock.constructorCalls[0];
+}
+
+describe("bedrock endpoint resolution", () => {
+	it("assigns eu-central-1 runtime URLs to built-in EU inference profiles", () => {
+		const model = getModel("amazon-bedrock", "eu.anthropic.claude-sonnet-4-5-20250929-v1:0");
+
+		expect(model.baseUrl).toBe("https://bedrock-runtime.eu-central-1.amazonaws.com");
+	});
+
+	it("does not pin standard AWS endpoints when AWS_REGION is configured", async () => {
+		process.env.AWS_REGION = "us-east-2";
+		const model = getModel("amazon-bedrock", "us.anthropic.claude-opus-4-7");
+
+		const config = await captureClientConfig(model);
+
+		expect(config.region).toBe("us-east-2");
+		expect(config.endpoint).toBeUndefined();
+	});
+
+	it("derives region from a built-in EU endpoint when no region or profile is configured", async () => {
+		const model = getModel("amazon-bedrock", "eu.anthropic.claude-sonnet-4-5-20250929-v1:0");
+
+		const config = await captureClientConfig(model);
+
+		expect(config.endpoint).toBe("https://bedrock-runtime.eu-central-1.amazonaws.com");
+		expect(config.region).toBe("eu-central-1");
+	});
+
+	it("still passes custom Bedrock endpoints through to the SDK client", async () => {
+		process.env.AWS_REGION = "us-west-2";
+		const baseModel = getModel("amazon-bedrock", "us.anthropic.claude-opus-4-7");
+		const model: Model<"bedrock-converse-stream"> = {
+			...baseModel,
+			baseUrl: "https://bedrock-vpc.example.com",
+		};
+
+		const config = await captureClientConfig(model);
+
+		expect(config.endpoint).toBe("https://bedrock-vpc.example.com");
+		expect(config.region).toBe("us-west-2");
+	});
+});