Fix streaming for z-ai in anthropic provider, add preliminary support for tool call streaming. Only reporting argument string deltas, not partial JSON objects

packages/ai/src/event-stream.ts

@@ -0,0 +1,82 @@
+import type { AssistantMessage, AssistantMessageEvent } from "./types";
+
+// Generic event stream class for async iteration
+export class EventStream<T, R = T> implements AsyncIterable<T> {
+	private queue: T[] = [];
+	private waiting: ((value: IteratorResult<T>) => void)[] = [];
+	private done = false;
+	private finalResultPromise: Promise<R>;
+	private resolveFinalResult!: (result: R) => void;
+
+	constructor(
+		private isComplete: (event: T) => boolean,
+		private extractResult: (event: T) => R,
+	) {
+		this.finalResultPromise = new Promise((resolve) => {
+			this.resolveFinalResult = resolve;
+		});
+	}
+
+	push(event: T): void {
+		if (this.done) return;
+
+		if (this.isComplete(event)) {
+			this.done = true;
+			this.resolveFinalResult(this.extractResult(event));
+		}
+
+		// Deliver to waiting consumer or queue it
+		const waiter = this.waiting.shift();
+		if (waiter) {
+			waiter({ value: event, done: false });
+		} else {
+			this.queue.push(event);
+		}
+	}
+
+	end(result?: R): void {
+		this.done = true;
+		if (result !== undefined) {
+			this.resolveFinalResult(result);
+		}
+		// Notify all waiting consumers that we're done
+		while (this.waiting.length > 0) {
+			const waiter = this.waiting.shift()!;
+			waiter({ value: undefined as any, done: true });
+		}
+	}
+
+	async *[Symbol.asyncIterator](): AsyncIterator<T> {
+		while (true) {
+			if (this.queue.length > 0) {
+				yield this.queue.shift()!;
+			} else if (this.done) {
+				return;
+			} else {
+				const result = await new Promise<IteratorResult<T>>((resolve) => this.waiting.push(resolve));
+				if (result.done) return;
+				yield result.value;
+			}
+		}
+	}
+
+	result(): Promise<R> {
+		return this.finalResultPromise;
+	}
+}
+
+export class AssistantMessageEventStream extends EventStream<AssistantMessageEvent, AssistantMessage> {
+	constructor() {
+		super(
+			(event) => event.type === "done" || event.type === "error",
+			(event) => {
+				if (event.type === "done") {
+					return event.message;
+				} else if (event.type === "error") {
+					return event.partial;
+				}
+				throw new Error("Unexpected event type for final result");
+			},
+		);
+	}
+}