feat(ai): Add Amazon Bedrock provider (#494)

Adds support for Amazon Bedrock with Claude models including:
- Full streaming support via Converse API
- Reasoning/thinking support for Claude models
- Cross-region inference model ID handling
- Multiple AWS credential sources (profile, IAM keys, API keys)
- Image support in messages and tool results
- Unicode surrogate sanitization

Also adds 'Adding a New Provider' documentation to AGENTS.md and README.

Co-authored-by: nickchan2 <nickchan2@users.noreply.github.com>

packages/ai/test/bedrock-models.test.ts

@@ -0,0 +1,66 @@
+/**
+ * A test suite to ensure all configured Amazon Bedrock models are usable.
+ *
+ * This is here to make sure we got correct model identifiers from models.dev and other sources.
+ * Because Amazon Bedrock requires cross-region inference in some models,
+ * plain model identifiers are not always usable and it requires tweaking of model identifiers to use cross-region inference.
+ * See https://docs.aws.amazon.com/bedrock/latest/userguide/inference-profiles-support.html#inference-profiles-support-system for more details.
+ *
+ * This test suite is not enabled by default unless AWS credentials and `BEDROCK_EXTENSIVE_MODEL_TEST` environment variables are set.
+ * This test suite takes ~2 minutes to run. Because not all models are available in all regions,
+ * it's recommended to use `us-west-2` region for best coverage for running this test suite.
+ *
+ * You can run this test suite with:
+ * ```bash
+ * $ AWS_REGION=us-west-2 BEDROCK_EXTENSIVE_MODEL_TEST=1 AWS_PROFILE=... npm test -- ./test/bedrock-models.test.ts
+ * ```
+ */
+
+import { describe, expect, it } from "vitest";
+import { getModels } from "../src/models.js";
+import { complete } from "../src/stream.js";
+import type { Context } from "../src/types.js";
+import { hasBedrockCredentials } from "./bedrock-utils.js";
+
+describe("Amazon Bedrock Models", () => {
+	const models = getModels("amazon-bedrock");
+
+	it("should get all available Bedrock models", () => {
+		expect(models.length).toBeGreaterThan(0);
+		console.log(`Found ${models.length} Bedrock models`);
+	});
+
+	if (hasBedrockCredentials() && process.env.BEDROCK_EXTENSIVE_MODEL_TEST) {
+		for (const model of models) {
+			it(`should make a simple request with ${model.id}`, { timeout: 10_000 }, async () => {
+				const context: Context = {
+					systemPrompt: "You are a helpful assistant. Be extremely concise.",
+					messages: [
+						{
+							role: "user",
+							content: "Reply with exactly: 'OK'",
+							timestamp: Date.now(),
+						},
+					],
+				};
+
+				const response = await complete(model, context);
+
+				expect(response.role).toBe("assistant");
+				expect(response.content).toBeTruthy();
+				expect(response.content.length).toBeGreaterThan(0);
+				expect(response.usage.input + response.usage.cacheRead).toBeGreaterThan(0);
+				expect(response.usage.output).toBeGreaterThan(0);
+				expect(response.errorMessage).toBeFalsy();
+
+				const textContent = response.content
+					.filter((b) => b.type === "text")
+					.map((b) => (b.type === "text" ? b.text : ""))
+					.join("")
+					.trim();
+				expect(textContent).toBeTruthy();
+				console.log(`${model.id}: ${textContent.substring(0, 100)}`);
+			});
+		}
+	}
+});