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/stream.test.ts

@@ -8,6 +8,7 @@ import { getModel } from "../src/models.js";
 import { complete, stream } from "../src/stream.js";
 import type { Api, Context, ImageContent, Model, OptionsForApi, Tool, ToolResultMessage } from "../src/types.js";
 import { StringEnum } from "../src/utils/typebox-helpers.js";
+import { hasBedrockCredentials } from "./bedrock-utils.js";
 import { resolveApiKey } from "./oauth.js";
 
 const __filename = fileURLToPath(import.meta.url);
@@ -356,7 +357,7 @@ describe("Generate E2E Tests", () => {
 			await handleStreaming(llm);
 		});
 
-		it("should handle ", { retry: 3 }, async () => {
+		it("should handle thinking", { retry: 3 }, async () => {
 			await handleThinking(llm, { thinking: { enabled: true, budgetTokens: 1024 } });
 		});
 
@@ -907,6 +908,34 @@ describe("Generate E2E Tests", () => {
 		});
 	});
 
+	describe.skipIf(!hasBedrockCredentials())("Amazon Bedrock Provider (claude-sonnet-4-5)", () => {
+		const llm = getModel("amazon-bedrock", "global.anthropic.claude-sonnet-4-5-20250929-v1:0");
+
+		it("should complete basic text generation", { retry: 3 }, async () => {
+			await basicTextGeneration(llm);
+		});
+
+		it("should handle tool calling", { retry: 3 }, async () => {
+			await handleToolCall(llm);
+		});
+
+		it("should handle streaming", { retry: 3 }, async () => {
+			await handleStreaming(llm);
+		});
+
+		it("should handle thinking", { retry: 3 }, async () => {
+			await handleThinking(llm, { reasoning: "medium" });
+		});
+
+		it("should handle multi-turn with thinking and tools", { retry: 3 }, async () => {
+			await multiTurn(llm, { reasoning: "high" });
+		});
+
+		it("should handle image input", { retry: 3 }, async () => {
+			await handleImage(llm);
+		});
+	});
+
 	// Check if ollama is installed and local LLM tests are enabled
 	let ollamaInstalled = false;
 	if (!process.env.PI_NO_LOCAL_LLM) {