fix(ai,coding-agent): make pi-ai browser-safe and move OAuth runtime exports

- add browser smoke bundling check to root check + pre-commit

- lazy-load Bedrock provider registration to avoid browser graph traversal

- remove top-level OAuth runtime exports from @mariozechner/pi-ai

- add @mariozechner/pi-ai/oauth subpath export and update coding-agent imports

- move proxy dispatcher init to coding-agent CLI (Node-only)

- document Bedrock/OAuth browser limitations

closes #1814

packages/ai/src/providers/register-builtins.ts

@@ -1,5 +1,13 @@
 import { clearApiProviders, registerApiProvider } from "../api-registry.js";
-import { streamBedrock, streamSimpleBedrock } from "./amazon-bedrock.js";
+import type {
+	AssistantMessage,
+	AssistantMessageEvent,
+	Context,
+	Model,
+	SimpleStreamOptions,
+	StreamOptions,
+} from "../types.js";
+import { AssistantMessageEventStream } from "../utils/event-stream.js";
 import { streamAnthropic, streamSimpleAnthropic } from "./anthropic.js";
 import { streamAzureOpenAIResponses, streamSimpleAzureOpenAIResponses } from "./azure-openai-responses.js";
 import { streamGoogle, streamSimpleGoogle } from "./google.js";
@@ -9,6 +17,100 @@ import { streamOpenAICodexResponses, streamSimpleOpenAICodexResponses } from "./
 import { streamOpenAICompletions, streamSimpleOpenAICompletions } from "./openai-completions.js";
 import { streamOpenAIResponses, streamSimpleOpenAIResponses } from "./openai-responses.js";
 
+interface BedrockProviderModule {
+	streamBedrock: (
+		model: Model<"bedrock-converse-stream">,
+		context: Context,
+		options?: StreamOptions,
+	) => AssistantMessageEventStream;
+	streamSimpleBedrock: (
+		model: Model<"bedrock-converse-stream">,
+		context: Context,
+		options?: SimpleStreamOptions,
+	) => AssistantMessageEventStream;
+}
+
+type DynamicImport = (specifier: string) => Promise<unknown>;
+
+const dynamicImport = new Function("specifier", "return import(specifier);") as DynamicImport;
+
+async function loadBedrockProviderModule(): Promise<BedrockProviderModule> {
+	const module = await dynamicImport("./amazon-bedrock.js");
+	return module as BedrockProviderModule;
+}
+
+function forwardStream(target: AssistantMessageEventStream, source: AssistantMessageEventStream): void {
+	(async () => {
+		for await (const event of source as AsyncIterable<AssistantMessageEvent>) {
+			target.push(event);
+		}
+		target.end();
+	})();
+}
+
+function createLazyLoadErrorMessage(model: Model<"bedrock-converse-stream">, error: unknown): AssistantMessage {
+	return {
+		role: "assistant",
+		content: [],
+		api: "bedrock-converse-stream",
+		provider: model.provider,
+		model: model.id,
+		usage: {
+			input: 0,
+			output: 0,
+			cacheRead: 0,
+			cacheWrite: 0,
+			totalTokens: 0,
+			cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
+		},
+		stopReason: "error",
+		errorMessage: error instanceof Error ? error.message : String(error),
+		timestamp: Date.now(),
+	};
+}
+
+function streamBedrockLazy(
+	model: Model<"bedrock-converse-stream">,
+	context: Context,
+	options?: StreamOptions,
+): AssistantMessageEventStream {
+	const outer = new AssistantMessageEventStream();
+
+	loadBedrockProviderModule()
+		.then((module) => {
+			const inner = module.streamBedrock(model, context, options);
+			forwardStream(outer, inner);
+		})
+		.catch((error) => {
+			const message = createLazyLoadErrorMessage(model, error);
+			outer.push({ type: "error", reason: "error", error: message });
+			outer.end(message);
+		});
+
+	return outer;
+}
+
+function streamSimpleBedrockLazy(
+	model: Model<"bedrock-converse-stream">,
+	context: Context,
+	options?: SimpleStreamOptions,
+): AssistantMessageEventStream {
+	const outer = new AssistantMessageEventStream();
+
+	loadBedrockProviderModule()
+		.then((module) => {
+			const inner = module.streamSimpleBedrock(model, context, options);
+			forwardStream(outer, inner);
+		})
+		.catch((error) => {
+			const message = createLazyLoadErrorMessage(model, error);
+			outer.push({ type: "error", reason: "error", error: message });
+			outer.end(message);
+		});
+
+	return outer;
+}
+
 export function registerBuiltInApiProviders(): void {
 	registerApiProvider({
 		api: "anthropic-messages",
@@ -60,8 +162,8 @@ export function registerBuiltInApiProviders(): void {
 
 	registerApiProvider({
 		api: "bedrock-converse-stream",
-		stream: streamBedrock,
-		streamSimple: streamSimpleBedrock,
+		stream: streamBedrockLazy,
+		streamSimple: streamSimpleBedrockLazy,
 	});
 }