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/package.json

@@ -13,6 +13,7 @@
 		"clean": "rm -rf dist",
 		"generate-models": "npx tsx scripts/generate-models.ts",
 		"build": "npm run generate-models && tsc -p tsconfig.build.json",
+		"dev": "tsc -p tsconfig.build.json --watch",
 		"check": "biome check --write .",
 		"test": "vitest --run",
 		"prepublishOnly": "npm run clean && npm run build"

packages/ai/src/agent/agent.ts

@@ -0,0 +1,231 @@
+import { EventStream } from "../event-stream";
+import { streamSimple } from "../generate.js";
+import type {
+	AssistantMessage,
+	Context,
+	Message,
+	Model,
+	SimpleGenerateOptions,
+	ToolResultMessage,
+	UserMessage,
+} from "../types.js";
+import type { AgentContext, AgentTool, AgentToolResult } from "./types";
+
+// Event types
+export type AgentEvent =
+	| { type: "message_start"; message: Message }
+	| { type: "message_update"; message: AssistantMessage }
+	| { type: "message_complete"; message: Message }
+	| { type: "tool_execution_start"; toolCallId: string; toolName: string; args: any }
+	| {
+			type: "tool_execution_complete";
+			toolCallId: string;
+			toolName: string;
+			result: AgentToolResult<any> | string;
+			isError: boolean;
+	  }
+	| { type: "turn_complete"; messages: AgentContext["messages"] };
+
+// Configuration for prompt execution
+export interface PromptConfig {
+	model: Model<any>;
+	apiKey: string;
+	enableThinking?: boolean;
+	preprocessor?: (messages: AgentContext["messages"], abortSignal?: AbortSignal) => Promise<AgentContext["messages"]>;
+}
+
+// Main prompt function - returns a stream of events
+export function prompt(
+	context: AgentContext,
+	config: PromptConfig,
+	prompt: UserMessage,
+	signal?: AbortSignal,
+): EventStream<AgentEvent, AgentContext["messages"]> {
+	const stream = new EventStream<AgentEvent, AgentContext["messages"]>(
+		(event) => event.type === "turn_complete",
+		(event) => (event.type === "turn_complete" ? event.messages : []),
+	);
+
+	// Run the prompt async
+	(async () => {
+		try {
+			// Track new messages generated during this prompt
+			const newMessages: AgentContext["messages"] = [];
+
+			// Create user message
+			const messages = [...context.messages, prompt];
+			newMessages.push(prompt);
+
+			stream.push({ type: "message_start", message: prompt });
+			stream.push({ type: "message_complete", message: prompt });
+
+			// Update context with new messages
+			const currentContext: AgentContext = {
+				...context,
+				messages,
+			};
+
+			// Keep looping while we have tool calls
+			let hasMoreToolCalls = true;
+			while (hasMoreToolCalls) {
+				// Stream assistant response
+				const assistantMessage = await streamAssistantResponse(currentContext, config, signal, stream);
+				newMessages.push(assistantMessage);
+
+				// Check for tool calls
+				const toolCalls = assistantMessage.content.filter((c) => c.type === "toolCall");
+				hasMoreToolCalls = toolCalls.length > 0;
+
+				if (hasMoreToolCalls) {
+					// Execute tool calls
+					const toolResults = await executeToolCalls(currentContext.tools, assistantMessage, signal, stream);
+					newMessages.push(...toolResults);
+
+					// Add tool results to context
+					currentContext.messages = [...currentContext.messages, ...toolResults];
+				}
+			}
+
+			stream.push({ type: "turn_complete", messages: newMessages });
+		} catch (error) {
+			// End stream on error
+			stream.end([]);
+			throw error;
+		}
+	})();
+
+	return stream;
+}
+
+// Helper functions
+async function streamAssistantResponse(
+	context: AgentContext,
+	config: PromptConfig,
+	signal: AbortSignal | undefined,
+	stream: EventStream<AgentEvent, AgentContext["messages"]>,
+): Promise<AssistantMessage> {
+	// Convert AgentContext to Context for streamSimple
+	// Use a copy of messages to avoid mutating the original context
+	const processedMessages = config.preprocessor
+		? await config.preprocessor(context.messages, signal)
+		: [...context.messages];
+	const processedContext: Context = {
+		systemPrompt: context.systemPrompt,
+		messages: [...processedMessages].map((m) => {
+			if (m.role === "toolResult") {
+				const { details, ...rest } = m;
+				return rest;
+			} else {
+				return m;
+			}
+		}),
+		tools: context.tools, // AgentTool extends Tool, so this works
+	};
+
+	const options: SimpleGenerateOptions = {
+		apiKey: config.apiKey,
+		signal,
+	};
+
+	if (config.model.reasoning && config.enableThinking) {
+		options.reasoning = "medium";
+	}
+
+	const response = await streamSimple(config.model, processedContext, options);
+
+	let partialMessage: AssistantMessage | null = null;
+	let addedPartial = false;
+
+	for await (const event of response) {
+		switch (event.type) {
+			case "start":
+				partialMessage = event.partial;
+				context.messages.push(partialMessage);
+				addedPartial = true;
+				stream.push({ type: "message_start", message: { ...partialMessage } });
+				break;
+
+			case "text_start":
+			case "text_delta":
+			case "thinking_start":
+			case "thinking_delta":
+			case "toolcall_start":
+			case "toolcall_delta":
+				if (partialMessage) {
+					partialMessage = event.partial;
+					context.messages[context.messages.length - 1] = partialMessage;
+					stream.push({ type: "message_update", message: { ...partialMessage } });
+				}
+				break;
+
+			case "done":
+			case "error": {
+				const finalMessage = await response.result();
+				if (addedPartial) {
+					context.messages[context.messages.length - 1] = finalMessage;
+				} else {
+					context.messages.push(finalMessage);
+				}
+				stream.push({ type: "message_complete", message: finalMessage });
+				return finalMessage;
+			}
+		}
+	}
+
+	return await response.result();
+}
+
+async function executeToolCalls<T>(
+	tools: AgentTool<T>[] | undefined,
+	assistantMessage: AssistantMessage,
+	signal: AbortSignal | undefined,
+	stream: EventStream<AgentEvent, Message[]>,
+): Promise<ToolResultMessage<T>[]> {
+	const toolCalls = assistantMessage.content.filter((c) => c.type === "toolCall");
+	const results: ToolResultMessage<any>[] = [];
+
+	for (const toolCall of toolCalls) {
+		const tool = tools?.find((t) => t.name === toolCall.name);
+
+		stream.push({
+			type: "tool_execution_start",
+			toolCallId: toolCall.id,
+			toolName: toolCall.name,
+			args: toolCall.arguments,
+		});
+
+		let resultOrError: AgentToolResult<T> | string;
+		let isError = false;
+
+		try {
+			if (!tool) throw new Error(`Tool ${toolCall.name} not found`);
+			resultOrError = await tool.execute(toolCall.arguments, toolCall.id, signal);
+		} catch (e) {
+			resultOrError = `Error: ${e instanceof Error ? e.message : String(e)}`;
+			isError = true;
+		}
+
+		stream.push({
+			type: "tool_execution_complete",
+			toolCallId: toolCall.id,
+			toolName: toolCall.name,
+			result: resultOrError,
+			isError,
+		});
+
+		const toolResultMessage: ToolResultMessage<T> = {
+			role: "toolResult",
+			toolCallId: toolCall.id,
+			toolName: toolCall.name,
+			output: typeof resultOrError === "string" ? resultOrError : resultOrError.output,
+			details: typeof resultOrError === "string" ? ({} as T) : resultOrError.details,
+			isError,
+		};
+
+		results.push(toolResultMessage);
+		stream.push({ type: "message_start", message: toolResultMessage });
+		stream.push({ type: "message_complete", message: toolResultMessage });
+	}
+
+	return results;
+}

packages/ai/src/agent/index.ts

@@ -0,0 +1,3 @@
+export { type AgentEvent, type PromptConfig, prompt } from "./agent";
+export * from "./tools";
+export type { AgentContext, AgentTool } from "./types";

packages/ai/src/agent/tools/calculate.ts

@@ -0,0 +1,34 @@
+import type { AgentTool } from "../../agent";
+
+export interface CalculateResult {
+	output: string;
+	details: undefined;
+}
+
+export function calculate(expression: string): CalculateResult {
+	try {
+		const result = new Function("return " + expression)();
+		return { output: `${expression} = ${result}`, details: undefined };
+	} catch (e: any) {
+		throw new Error(e.message || String(e));
+	}
+}
+
+export const calculateTool: AgentTool<undefined> = {
+	label: "Calculator",
+	name: "calculate",
+	description: "Evaluate mathematical expressions",
+	parameters: {
+		type: "object",
+		properties: {
+			expression: {
+				type: "string",
+				description: "The mathematical expression to evaluate",
+			},
+		},
+		required: ["expression"],
+	},
+	execute: async (args: { expression: string }) => {
+		return calculate(args.expression);
+	},
+};

packages/ai/src/agent/tools/get-current-time.ts

@@ -0,0 +1,44 @@
+import type { AgentTool } from "../../agent";
+import type { AgentToolResult } from "../types";
+
+export interface GetCurrentTimeResult extends AgentToolResult<{ utcTimestamp: number }> {}
+
+export async function getCurrentTime(timezone?: string): Promise<GetCurrentTimeResult> {
+	const date = new Date();
+	if (timezone) {
+		try {
+			return {
+				output: date.toLocaleString("en-US", {
+					timeZone: timezone,
+					dateStyle: "full",
+					timeStyle: "long",
+				}),
+				details: { utcTimestamp: date.getTime() },
+			};
+		} catch (e) {
+			throw new Error(`Invalid timezone: ${timezone}. Current UTC time: ${date.toISOString()}`);
+		}
+	}
+	return {
+		output: date.toLocaleString("en-US", { dateStyle: "full", timeStyle: "long" }),
+		details: { utcTimestamp: date.getTime() },
+	};
+}
+
+export const getCurrentTimeTool: AgentTool<{ utcTimestamp: number }> = {
+	label: "Current Time",
+	name: "get_current_time",
+	description: "Get the current date and time",
+	parameters: {
+		type: "object",
+		properties: {
+			timezone: {
+				type: "string",
+				description: "Optional timezone (e.g., 'America/New_York', 'Europe/London')",
+			},
+		},
+	},
+	execute: async (args: { timezone?: string }) => {
+		return getCurrentTime(args.timezone);
+	},
+};

packages/ai/src/agent/tools/index.ts

@@ -0,0 +1,2 @@
+export { calculate, calculateTool } from "./calculate";
+export { getCurrentTime, getCurrentTimeTool } from "./get-current-time";

packages/ai/src/agent/types.ts

@@ -0,0 +1,22 @@
+import type { Message, Tool } from "../types.js";
+
+export interface AgentToolResult<T> {
+	// Output of the tool to be given to the LLM in ToolResultMessage.content
+	output: string;
+	// Details to be displayed in a UI or loggedty
+	details: T;
+}
+
+// AgentTool extends Tool but adds the execute function
+export interface AgentTool<TDetails> extends Tool {
+	// A human-readable label for the tool to be displayed in UI
+	label: string;
+	execute: (params: any, toolCallId: string, signal?: AbortSignal) => Promise<AgentToolResult<TDetails>>;
+}
+
+// AgentContext is like Context but uses AgentTool
+export interface AgentContext {
+	systemPrompt: string;
+	messages: Message[];
+	tools?: AgentTool<any>[];
+}

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");
+			},
+		);
+	}
+}

packages/ai/src/generate.ts

@@ -5,9 +5,8 @@ import { type OpenAIResponsesOptions, streamOpenAIResponses } from "./providers/
 import type {
 	Api,
 	AssistantMessage,
-	AssistantMessageEvent,
+	AssistantMessageEventStream,
 	Context,
-	GenerateStream,
 	KnownProvider,
 	Model,
 	OptionsForApi,
@@ -15,73 +14,6 @@ import type {
 	SimpleGenerateOptions,
 } from "./types.js";
 
-export class QueuedGenerateStream implements GenerateStream {
-	private queue: AssistantMessageEvent[] = [];
-	private waiting: ((value: IteratorResult<AssistantMessageEvent>) => void)[] = [];
-	private done = false;
-	private finalMessagePromise: Promise<AssistantMessage>;
-	private resolveFinalMessage!: (message: AssistantMessage) => void;
-
-	constructor() {
-		this.finalMessagePromise = new Promise((resolve) => {
-			this.resolveFinalMessage = resolve;
-		});
-	}
-
-	push(event: AssistantMessageEvent): void {
-		if (this.done) return;
-
-		if (event.type === "done") {
-			this.done = true;
-			this.resolveFinalMessage(event.message);
-		}
-		if (event.type === "error") {
-			this.done = true;
-			this.resolveFinalMessage(event.partial);
-		}
-
-		// 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(): void {
-		this.done = true;
-		// 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<AssistantMessageEvent> {
-		while (true) {
-			// If we have queued events, yield them
-			if (this.queue.length > 0) {
-				yield this.queue.shift()!;
-			} else if (this.done) {
-				// No more events and we're done
-				return;
-			} else {
-				// Wait for next event
-				const result = await new Promise<IteratorResult<AssistantMessageEvent>>((resolve) =>
-					this.waiting.push(resolve),
-				);
-				if (result.done) return;
-				yield result.value;
-			}
-		}
-	}
-
-	finalMessage(): Promise<AssistantMessage> {
-		return this.finalMessagePromise;
-	}
-}
-
 const apiKeys: Map<string, string> = new Map();
 
 export function setApiKey(provider: KnownProvider, key: string): void;
@@ -117,7 +49,7 @@ export function stream<TApi extends Api>(
 	model: Model<TApi>,
 	context: Context,
 	options?: OptionsForApi<TApi>,
-): GenerateStream {
+): AssistantMessageEventStream {
 	const apiKey = options?.apiKey || getApiKey(model.provider);
 	if (!apiKey) {
 		throw new Error(`No API key for provider: ${model.provider}`);
@@ -152,14 +84,14 @@ export async function complete<TApi extends Api>(
 	options?: OptionsForApi<TApi>,
 ): Promise<AssistantMessage> {
 	const s = stream(model, context, options);
-	return s.finalMessage();
+	return s.result();
 }
 
 export function streamSimple<TApi extends Api>(
 	model: Model<TApi>,
 	context: Context,
 	options?: SimpleGenerateOptions,
-): GenerateStream {
+): AssistantMessageEventStream {
 	const apiKey = options?.apiKey || getApiKey(model.provider);
 	if (!apiKey) {
 		throw new Error(`No API key for provider: ${model.provider}`);
@@ -175,7 +107,7 @@ export async function completeSimple<TApi extends Api>(
 	options?: SimpleGenerateOptions,
 ): Promise<AssistantMessage> {
 	const s = streamSimple(model, context, options);
-	return s.finalMessage();
+	return s.result();
 }
 
 function mapOptionsForApi<TApi extends Api>(

packages/ai/src/index.ts

@@ -1,3 +1,4 @@
+export * from "./agent/index.js";
 export * from "./generate.js";
 export * from "./models.js";
 export * from "./providers/anthropic.js";

packages/ai/src/providers/anthropic.ts

@@ -4,7 +4,7 @@ import type {
 	MessageCreateParamsStreaming,
 	MessageParam,
 } from "@anthropic-ai/sdk/resources/messages.js";
-import { QueuedGenerateStream } from "../generate.js";
+import { AssistantMessageEventStream } from "../event-stream.js";
 import { calculateCost } from "../models.js";
 import type {
 	Api,
@@ -12,7 +12,6 @@ import type {
 	Context,
 	GenerateFunction,
 	GenerateOptions,
-	GenerateStream,
 	Message,
 	Model,
 	StopReason,
@@ -20,8 +19,9 @@ import type {
 	ThinkingContent,
 	Tool,
 	ToolCall,
+	ToolResultMessage,
 } from "../types.js";
-import { transformMessages } from "./utils.js";
+import { transformMessages } from "./transorm-messages.js";
 
 export interface AnthropicOptions extends GenerateOptions {
 	thinkingEnabled?: boolean;
@@ -33,8 +33,8 @@ export const streamAnthropic: GenerateFunction<"anthropic-messages"> = (
 	model: Model<"anthropic-messages">,
 	context: Context,
 	options?: AnthropicOptions,
-): GenerateStream => {
+): AssistantMessageEventStream => {
-	const stream = new QueuedGenerateStream();
+	const stream = new AssistantMessageEventStream();
 
 	(async () => {
 		const output: AssistantMessage = {
@@ -59,93 +59,114 @@ export const streamAnthropic: GenerateFunction<"anthropic-messages"> = (
 			const anthropicStream = client.messages.stream({ ...params, stream: true }, { signal: options?.signal });
 			stream.push({ type: "start", partial: output });
 
-			let currentBlock: ThinkingContent | TextContent | (ToolCall & { partialJson: string }) | null = null;
+			type Block = (ThinkingContent | TextContent | (ToolCall & { partialJson: string })) & { index: number };
+			const blocks = output.content as Block[];
 
 			for await (const event of anthropicStream) {
 				if (event.type === "content_block_start") {
 					if (event.content_block.type === "text") {
-						currentBlock = {
+						const block: Block = {
 							type: "text",
 							text: "",
+							index: event.index,
 						};
-						output.content.push(currentBlock);
+						output.content.push(block);
-						stream.push({ type: "text_start", partial: output });
+						stream.push({ type: "text_start", contentIndex: output.content.length - 1, partial: output });
 					} else if (event.content_block.type === "thinking") {
-						currentBlock = {
+						const block: Block = {
 							type: "thinking",
 							thinking: "",
 							thinkingSignature: "",
+							index: event.index,
 						};
-						output.content.push(currentBlock);
+						output.content.push(block);
-						stream.push({ type: "thinking_start", partial: output });
+						stream.push({ type: "thinking_start", contentIndex: output.content.length - 1, partial: output });
 					} else if (event.content_block.type === "tool_use") {
-						// We wait for the full tool use to be streamed
+						const block: Block = {
-						currentBlock = {
 							type: "toolCall",
 							id: event.content_block.id,
 							name: event.content_block.name,
 							arguments: event.content_block.input as Record<string, any>,
 							partialJson: "",
+							index: event.index,
 						};
+						output.content.push(block);
+						stream.push({ type: "toolcall_start", contentIndex: output.content.length - 1, partial: output });
 					}
 				} else if (event.type === "content_block_delta") {
 					if (event.delta.type === "text_delta") {
-						if (currentBlock && currentBlock.type === "text") {
+						const index = blocks.findIndex((b) => b.index === event.index);
-							currentBlock.text += event.delta.text;
+						const block = blocks[index];
+						if (block && block.type === "text") {
+							block.text += event.delta.text;
 							stream.push({
 								type: "text_delta",
+								contentIndex: index,
 								delta: event.delta.text,
 								partial: output,
 							});
 						}
 					} else if (event.delta.type === "thinking_delta") {
-						if (currentBlock && currentBlock.type === "thinking") {
+						const index = blocks.findIndex((b) => b.index === event.index);
-							currentBlock.thinking += event.delta.thinking;
+						const block = blocks[index];
+						if (block && block.type === "thinking") {
+							block.thinking += event.delta.thinking;
 							stream.push({
 								type: "thinking_delta",
+								contentIndex: index,
 								delta: event.delta.thinking,
 								partial: output,
 							});
 						}
 					} else if (event.delta.type === "input_json_delta") {
-						if (currentBlock && currentBlock.type === "toolCall") {
+						const index = blocks.findIndex((b) => b.index === event.index);
-							currentBlock.partialJson += event.delta.partial_json;
+						const block = blocks[index];
+						if (block && block.type === "toolCall") {
+							block.partialJson += event.delta.partial_json;
+							stream.push({
+								type: "toolcall_delta",
+								contentIndex: index,
+								delta: event.delta.partial_json,
+								partial: output,
+							});
 						}
 					} else if (event.delta.type === "signature_delta") {
-						if (currentBlock && currentBlock.type === "thinking") {
+						const index = blocks.findIndex((b) => b.index === event.index);
-							currentBlock.thinkingSignature = currentBlock.thinkingSignature || "";
+						const block = blocks[index];
-							currentBlock.thinkingSignature += event.delta.signature;
+						if (block && block.type === "thinking") {
+							block.thinkingSignature = block.thinkingSignature || "";
+							block.thinkingSignature += event.delta.signature;
 						}
 					}
 				} else if (event.type === "content_block_stop") {
-					if (currentBlock) {
+					const index = blocks.findIndex((b) => b.index === event.index);
-						if (currentBlock.type === "text") {
+					const block = blocks[index];
+					if (block) {
+						delete (block as any).index;
+						if (block.type === "text") {
 							stream.push({
 								type: "text_end",
-								content: currentBlock.text,
+								contentIndex: index,
+								content: block.text,
 								partial: output,
 							});
-						} else if (currentBlock.type === "thinking") {
+						} else if (block.type === "thinking") {
 							stream.push({
 								type: "thinking_end",
-								content: currentBlock.thinking,
+								contentIndex: index,
+								content: block.thinking,
 								partial: output,
 							});
-						} else if (currentBlock.type === "toolCall") {
+						} else if (block.type === "toolCall") {
-							const finalToolCall: ToolCall = {
+							block.arguments = JSON.parse(block.partialJson);
-								type: "toolCall",
+							delete (block as any).partialJson;
-								id: currentBlock.id,
-								name: currentBlock.name,
-								arguments: JSON.parse(currentBlock.partialJson),
-							};
-							output.content.push(finalToolCall);
 							stream.push({
-								type: "toolCall",
+								type: "toolcall_end",
-								toolCall: finalToolCall,
+								contentIndex: index,
+								toolCall: block,
 								partial: output,
 							});
 						}
-						currentBlock = null;
 					}
 				} else if (event.type === "message_delta") {
 					if (event.delta.stop_reason) {
@@ -166,6 +187,7 @@ export const streamAnthropic: GenerateFunction<"anthropic-messages"> = (
 			stream.push({ type: "done", reason: output.stopReason, message: output });
 			stream.end();
 		} catch (error) {
+			for (const block of output.content) delete (block as any).index;
 			output.stopReason = "error";
 			output.error = error instanceof Error ? error.message : JSON.stringify(error);
 			stream.push({ type: "error", error: output.error, partial: output });
@@ -294,7 +316,9 @@ function convertMessages(messages: Message[], model: Model<"anthropic-messages">
 	// Transform messages for cross-provider compatibility
 	const transformedMessages = transformMessages(messages, model);
 
-	for (const msg of transformedMessages) {
+	for (let i = 0; i < transformedMessages.length; i++) {
+		const msg = transformedMessages[i];
+
 		if (msg.role === "user") {
 			if (typeof msg.content === "string") {
 				if (msg.content.trim().length > 0) {
@@ -366,16 +390,37 @@ function convertMessages(messages: Message[], model: Model<"anthropic-messages">
 				content: blocks,
 			});
 		} else if (msg.role === "toolResult") {
-			params.push({
+			// Collect all consecutive toolResult messages
-				role: "user",
+			const toolResults: ContentBlockParam[] = [];
-				content: [
+
-					{
+			// Add the current tool result
+			toolResults.push({
 				type: "tool_result",
 				tool_use_id: sanitizeToolCallId(msg.toolCallId),
-						content: msg.content,
+				content: msg.output,
 				is_error: msg.isError,
-					},
+			});
-				],
+
+			// Look ahead for consecutive toolResult messages
+			let j = i + 1;
+			while (j < transformedMessages.length && transformedMessages[j].role === "toolResult") {
+				const nextMsg = transformedMessages[j] as ToolResultMessage; // We know it's a toolResult
+				toolResults.push({
+					type: "tool_result",
+					tool_use_id: sanitizeToolCallId(nextMsg.toolCallId),
+					content: nextMsg.output,
+					is_error: nextMsg.isError,
+				});
+				j++;
+			}
+
+			// Skip the messages we've already processed
+			i = j - 1;
+
+			// Add a single user message with all tool results
+			params.push({
+				role: "user",
+				content: toolResults,
 			});
 		}
 	}

packages/ai/src/providers/google.ts

@@ -7,7 +7,7 @@ import {
 	GoogleGenAI,
 	type Part,
 } from "@google/genai";
-import { QueuedGenerateStream } from "../generate.js";
+import { AssistantMessageEventStream } from "../event-stream.js";
 import { calculateCost } from "../models.js";
 import type {
 	Api,
@@ -15,7 +15,6 @@ import type {
 	Context,
 	GenerateFunction,
 	GenerateOptions,
-	GenerateStream,
 	Model,
 	StopReason,
 	TextContent,
@@ -23,7 +22,7 @@ import type {
 	Tool,
 	ToolCall,
 } from "../types.js";
-import { transformMessages } from "./utils.js";
+import { transformMessages } from "./transorm-messages.js";
 
 export interface GoogleOptions extends GenerateOptions {
 	toolChoice?: "auto" | "none" | "any";
@@ -40,8 +39,8 @@ export const streamGoogle: GenerateFunction<"google-generative-ai"> = (
 	model: Model<"google-generative-ai">,
 	context: Context,
 	options?: GoogleOptions,
-): GenerateStream => {
+): AssistantMessageEventStream => {
-	const stream = new QueuedGenerateStream();
+	const stream = new AssistantMessageEventStream();
 
 	(async () => {
 		const output: AssistantMessage = {
@@ -67,6 +66,8 @@ export const streamGoogle: GenerateFunction<"google-generative-ai"> = (
 
 			stream.push({ type: "start", partial: output });
 			let currentBlock: TextContent | ThinkingContent | null = null;
+			const blocks = output.content;
+			const blockIndex = () => blocks.length - 1;
 			for await (const chunk of googleStream) {
 				const candidate = chunk.candidates?.[0];
 				if (candidate?.content?.parts) {
@@ -82,12 +83,14 @@ export const streamGoogle: GenerateFunction<"google-generative-ai"> = (
 									if (currentBlock.type === "text") {
 										stream.push({
 											type: "text_end",
+											contentIndex: blocks.length - 1,
 											content: currentBlock.text,
 											partial: output,
 										});
 									} else {
 										stream.push({
 											type: "thinking_end",
+											contentIndex: blockIndex(),
 											content: currentBlock.thinking,
 											partial: output,
 										});
@@ -95,10 +98,10 @@ export const streamGoogle: GenerateFunction<"google-generative-ai"> = (
 								}
 								if (isThinking) {
 									currentBlock = { type: "thinking", thinking: "", thinkingSignature: undefined };
-									stream.push({ type: "thinking_start", partial: output });
+									stream.push({ type: "thinking_start", contentIndex: blockIndex(), partial: output });
 								} else {
 									currentBlock = { type: "text", text: "" };
-									stream.push({ type: "text_start", partial: output });
+									stream.push({ type: "text_start", contentIndex: blockIndex(), partial: output });
 								}
 								output.content.push(currentBlock);
 							}
@@ -107,12 +110,18 @@ export const streamGoogle: GenerateFunction<"google-generative-ai"> = (
 								currentBlock.thinkingSignature = part.thoughtSignature;
 								stream.push({
 									type: "thinking_delta",
+									contentIndex: blockIndex(),
 									delta: part.text,
 									partial: output,
 								});
 							} else {
 								currentBlock.text += part.text;
-								stream.push({ type: "text_delta", delta: part.text, partial: output });
+								stream.push({
+									type: "text_delta",
+									contentIndex: blockIndex(),
+									delta: part.text,
+									partial: output,
+								});
 							}
 						}
 
@@ -121,12 +130,14 @@ export const streamGoogle: GenerateFunction<"google-generative-ai"> = (
 								if (currentBlock.type === "text") {
 									stream.push({
 										type: "text_end",
+										contentIndex: blockIndex(),
 										content: currentBlock.text,
 										partial: output,
 									});
 								} else {
 									stream.push({
 										type: "thinking_end",
+										contentIndex: blockIndex(),
 										content: currentBlock.thinking,
 										partial: output,
 									});
@@ -149,7 +160,14 @@ export const streamGoogle: GenerateFunction<"google-generative-ai"> = (
 								arguments: part.functionCall.args as Record<string, any>,
 							};
 							output.content.push(toolCall);
-							stream.push({ type: "toolCall", toolCall, partial: output });
+							stream.push({ type: "toolcall_start", contentIndex: blockIndex(), partial: output });
+							stream.push({
+								type: "toolcall_delta",
+								contentIndex: blockIndex(),
+								delta: JSON.stringify(toolCall.arguments),
+								partial: output,
+							});
+							stream.push({ type: "toolcall_end", contentIndex: blockIndex(), toolCall, partial: output });
 						}
 					}
 				}
@@ -182,9 +200,19 @@ export const streamGoogle: GenerateFunction<"google-generative-ai"> = (
 
 			if (currentBlock) {
 				if (currentBlock.type === "text") {
-					stream.push({ type: "text_end", content: currentBlock.text, partial: output });
+					stream.push({
+						type: "text_end",
+						contentIndex: blockIndex(),
+						content: currentBlock.text,
+						partial: output,
+					});
 				} else {
-					stream.push({ type: "thinking_end", content: currentBlock.thinking, partial: output });
+					stream.push({
+						type: "thinking_end",
+						contentIndex: blockIndex(),
+						content: currentBlock.thinking,
+						partial: output,
+					});
 				}
 			}
 
@@ -333,7 +361,7 @@ function convertMessages(model: Model<"google-generative-ai">, context: Context)
 							id: msg.toolCallId,
 							name: msg.toolName,
 							response: {
-								result: msg.content,
+								result: msg.output,
 								isError: msg.isError,
 							},
 						},

packages/ai/src/providers/openai-completions.ts

@@ -7,14 +7,13 @@ import type {
 	ChatCompletionContentPartText,
 	ChatCompletionMessageParam,
 } from "openai/resources/chat/completions.js";
-import { QueuedGenerateStream } from "../generate.js";
+import { AssistantMessageEventStream } from "../event-stream.js";
 import { calculateCost } from "../models.js";
 import type {
 	AssistantMessage,
 	Context,
 	GenerateFunction,
 	GenerateOptions,
-	GenerateStream,
 	Model,
 	StopReason,
 	TextContent,
@@ -22,7 +21,7 @@ import type {
 	Tool,
 	ToolCall,
 } from "../types.js";
-import { transformMessages } from "./utils.js";
+import { transformMessages } from "./transorm-messages.js";
 
 export interface OpenAICompletionsOptions extends GenerateOptions {
 	toolChoice?: "auto" | "none" | "required" | { type: "function"; function: { name: string } };
@@ -33,8 +32,8 @@ export const streamOpenAICompletions: GenerateFunction<"openai-completions"> = (
 	model: Model<"openai-completions">,
 	context: Context,
 	options?: OpenAICompletionsOptions,
-): GenerateStream => {
+): AssistantMessageEventStream => {
-	const stream = new QueuedGenerateStream();
+	const stream = new AssistantMessageEventStream();
 
 	(async () => {
 		const output: AssistantMessage = {
@@ -60,6 +59,37 @@ export const streamOpenAICompletions: GenerateFunction<"openai-completions"> = (
 			stream.push({ type: "start", partial: output });
 
 			let currentBlock: TextContent | ThinkingContent | (ToolCall & { partialArgs?: string }) | null = null;
+			const blocks = output.content;
+			const blockIndex = () => blocks.length - 1;
+			const finishCurrentBlock = (block?: typeof currentBlock) => {
+				if (block) {
+					if (block.type === "text") {
+						stream.push({
+							type: "text_end",
+							contentIndex: blockIndex(),
+							content: block.text,
+							partial: output,
+						});
+					} else if (block.type === "thinking") {
+						stream.push({
+							type: "thinking_end",
+							contentIndex: blockIndex(),
+							content: block.thinking,
+							partial: output,
+						});
+					} else if (block.type === "toolCall") {
+						block.arguments = JSON.parse(block.partialArgs || "{}");
+						delete block.partialArgs;
+						stream.push({
+							type: "toolcall_end",
+							contentIndex: blockIndex(),
+							toolCall: block,
+							partial: output,
+						});
+					}
+				}
+			};
+
 			for await (const chunk of openaiStream) {
 				if (chunk.usage) {
 					output.usage = {
@@ -94,120 +124,54 @@ export const streamOpenAICompletions: GenerateFunction<"openai-completions"> = (
 						choice.delta.content.length > 0
 					) {
 						if (!currentBlock || currentBlock.type !== "text") {
-							if (currentBlock) {
+							finishCurrentBlock(currentBlock);
-								if (currentBlock.type === "thinking") {
-									stream.push({
-										type: "thinking_end",
-										content: currentBlock.thinking,
-										partial: output,
-									});
-								} else if (currentBlock.type === "toolCall") {
-									currentBlock.arguments = JSON.parse(currentBlock.partialArgs || "{}");
-									delete currentBlock.partialArgs;
-									stream.push({
-										type: "toolCall",
-										toolCall: currentBlock as ToolCall,
-										partial: output,
-									});
-								}
-							}
 							currentBlock = { type: "text", text: "" };
 							output.content.push(currentBlock);
-							stream.push({ type: "text_start", partial: output });
+							stream.push({ type: "text_start", contentIndex: blockIndex(), partial: output });
 						}
 
 						if (currentBlock.type === "text") {
 							currentBlock.text += choice.delta.content;
 							stream.push({
 								type: "text_delta",
+								contentIndex: blockIndex(),
 								delta: choice.delta.content,
 								partial: output,
 							});
 						}
 					}
 
-					// Some endpoints return reasoning in reasoning_content (llama.cpp)
+					// Some endpoints return reasoning in reasoning_content (llama.cpp),
+					// or reasoning (other openai compatible endpoints)
+					const reasoningFields = ["reasoning_content", "reasoning"];
+					for (const field of reasoningFields) {
 						if (
-						(choice.delta as any).reasoning_content !== null &&
+							(choice.delta as any)[field] !== null &&
-						(choice.delta as any).reasoning_content !== undefined &&
+							(choice.delta as any)[field] !== undefined &&
-						(choice.delta as any).reasoning_content.length > 0
+							(choice.delta as any)[field].length > 0
 						) {
 							if (!currentBlock || currentBlock.type !== "thinking") {
-							if (currentBlock) {
+								finishCurrentBlock(currentBlock);
-								if (currentBlock.type === "text") {
-									stream.push({
-										type: "text_end",
-										content: currentBlock.text,
-										partial: output,
-									});
-								} else if (currentBlock.type === "toolCall") {
-									currentBlock.arguments = JSON.parse(currentBlock.partialArgs || "{}");
-									delete currentBlock.partialArgs;
-									stream.push({
-										type: "toolCall",
-										toolCall: currentBlock as ToolCall,
-										partial: output,
-									});
-								}
-							}
 								currentBlock = {
 									type: "thinking",
 									thinking: "",
-								thinkingSignature: "reasoning_content",
+									thinkingSignature: field,
 								};
 								output.content.push(currentBlock);
-							stream.push({ type: "thinking_start", partial: output });
+								stream.push({ type: "thinking_start", contentIndex: blockIndex(), partial: output });
 							}
 
 							if (currentBlock.type === "thinking") {
-							const delta = (choice.delta as any).reasoning_content;
+								const delta = (choice.delta as any)[field];
 								currentBlock.thinking += delta;
 								stream.push({
 									type: "thinking_delta",
+									contentIndex: blockIndex(),
 									delta,
 									partial: output,
 								});
 							}
 						}
-
-					// Some endpoints return reasoning in reasining (ollama, xAI, ...)
-					if (
-						(choice.delta as any).reasoning !== null &&
-						(choice.delta as any).reasoning !== undefined &&
-						(choice.delta as any).reasoning.length > 0
-					) {
-						if (!currentBlock || currentBlock.type !== "thinking") {
-							if (currentBlock) {
-								if (currentBlock.type === "text") {
-									stream.push({
-										type: "text_end",
-										content: currentBlock.text,
-										partial: output,
-									});
-								} else if (currentBlock.type === "toolCall") {
-									currentBlock.arguments = JSON.parse(currentBlock.partialArgs || "{}");
-									delete currentBlock.partialArgs;
-									stream.push({
-										type: "toolCall",
-										toolCall: currentBlock as ToolCall,
-										partial: output,
-									});
-								}
-							}
-							currentBlock = {
-								type: "thinking",
-								thinking: "",
-								thinkingSignature: "reasoning",
-							};
-							output.content.push(currentBlock);
-							stream.push({ type: "thinking_start", partial: output });
-						}
-
-						if (currentBlock.type === "thinking") {
-							const delta = (choice.delta as any).reasoning;
-							currentBlock.thinking += delta;
-							stream.push({ type: "thinking_delta", delta, partial: output });
-						}
 					}
 
 					if (choice?.delta?.tool_calls) {
@@ -217,30 +181,7 @@ export const streamOpenAICompletions: GenerateFunction<"openai-completions"> = (
 								currentBlock.type !== "toolCall" ||
 								(toolCall.id && currentBlock.id !== toolCall.id)
 							) {
-								if (currentBlock) {
+								finishCurrentBlock(currentBlock);
-									if (currentBlock.type === "text") {
-										stream.push({
-											type: "text_end",
-											content: currentBlock.text,
-											partial: output,
-										});
-									} else if (currentBlock.type === "thinking") {
-										stream.push({
-											type: "thinking_end",
-											content: currentBlock.thinking,
-											partial: output,
-										});
-									} else if (currentBlock.type === "toolCall") {
-										currentBlock.arguments = JSON.parse(currentBlock.partialArgs || "{}");
-										delete currentBlock.partialArgs;
-										stream.push({
-											type: "toolCall",
-											toolCall: currentBlock as ToolCall,
-											partial: output,
-										});
-									}
-								}
-
 								currentBlock = {
 									type: "toolCall",
 									id: toolCall.id || "",
@@ -249,43 +190,30 @@ export const streamOpenAICompletions: GenerateFunction<"openai-completions"> = (
 									partialArgs: "",
 								};
 								output.content.push(currentBlock);
+								stream.push({ type: "toolcall_start", contentIndex: blockIndex(), partial: output });
 							}
 
 							if (currentBlock.type === "toolCall") {
 								if (toolCall.id) currentBlock.id = toolCall.id;
 								if (toolCall.function?.name) currentBlock.name = toolCall.function.name;
+								let delta = "";
 								if (toolCall.function?.arguments) {
+									delta = toolCall.function.arguments;
 									currentBlock.partialArgs += toolCall.function.arguments;
 								}
+								stream.push({
+									type: "toolcall_delta",
+									contentIndex: blockIndex(),
+									delta,
+									partial: output,
+								});
 							}
 						}
 					}
 				}
 			}
 
-			if (currentBlock) {
+			finishCurrentBlock(currentBlock);
-				if (currentBlock.type === "text") {
-					stream.push({
-						type: "text_end",
-						content: currentBlock.text,
-						partial: output,
-					});
-				} else if (currentBlock.type === "thinking") {
-					stream.push({
-						type: "thinking_end",
-						content: currentBlock.thinking,
-						partial: output,
-					});
-				} else if (currentBlock.type === "toolCall") {
-					currentBlock.arguments = JSON.parse(currentBlock.partialArgs || "{}");
-					delete currentBlock.partialArgs;
-					stream.push({
-						type: "toolCall",
-						toolCall: currentBlock as ToolCall,
-						partial: output,
-					});
-				}
-			}
 
 			if (options?.signal?.aborted) {
 				throw new Error("Request was aborted");
@@ -438,7 +366,7 @@ function convertMessages(model: Model<"openai-completions">, context: Context):
 		} else if (msg.role === "toolResult") {
 			params.push({
 				role: "tool",
-				content: msg.content,
+				content: msg.output,
 				tool_call_id: msg.toolCallId,
 			});
 		}

packages/ai/src/providers/openai-responses.ts

@@ -10,7 +10,7 @@ import type {
 	ResponseOutputMessage,
 	ResponseReasoningItem,
 } from "openai/resources/responses/responses.js";
-import { QueuedGenerateStream } from "../generate.js";
+import { AssistantMessageEventStream } from "../event-stream.js";
 import { calculateCost } from "../models.js";
 import type {
 	Api,
@@ -18,7 +18,6 @@ import type {
 	Context,
 	GenerateFunction,
 	GenerateOptions,
-	GenerateStream,
 	Model,
 	StopReason,
 	TextContent,
@@ -26,7 +25,7 @@ import type {
 	Tool,
 	ToolCall,
 } from "../types.js";
-import { transformMessages } from "./utils.js";
+import { transformMessages } from "./transorm-messages.js";
 
 // OpenAI Responses-specific options
 export interface OpenAIResponsesOptions extends GenerateOptions {
@@ -41,8 +40,8 @@ export const streamOpenAIResponses: GenerateFunction<"openai-responses"> = (
 	model: Model<"openai-responses">,
 	context: Context,
 	options?: OpenAIResponsesOptions,
-): GenerateStream => {
+): AssistantMessageEventStream => {
-	const stream = new QueuedGenerateStream();
+	const stream = new AssistantMessageEventStream();
 
 	// Start async processing
 	(async () => {
@@ -70,7 +69,9 @@ export const streamOpenAIResponses: GenerateFunction<"openai-responses"> = (
 			stream.push({ type: "start", partial: output });
 
 			let currentItem: ResponseReasoningItem | ResponseOutputMessage | ResponseFunctionToolCall | null = null;
-			let currentBlock: ThinkingContent | TextContent | ToolCall | null = null;
+			let currentBlock: ThinkingContent | TextContent | (ToolCall & { partialJson: string }) | null = null;
+			const blocks = output.content;
+			const blockIndex = () => blocks.length - 1;
 
 			for await (const event of openaiStream) {
 				// Handle output item start
@@ -80,12 +81,23 @@ export const streamOpenAIResponses: GenerateFunction<"openai-responses"> = (
 						currentItem = item;
 						currentBlock = { type: "thinking", thinking: "" };
 						output.content.push(currentBlock);
-						stream.push({ type: "thinking_start", partial: output });
+						stream.push({ type: "thinking_start", contentIndex: blockIndex(), partial: output });
 					} else if (item.type === "message") {
 						currentItem = item;
 						currentBlock = { type: "text", text: "" };
 						output.content.push(currentBlock);
-						stream.push({ type: "text_start", partial: output });
+						stream.push({ type: "text_start", contentIndex: blockIndex(), partial: output });
+					} else if (item.type === "function_call") {
+						currentItem = item;
+						currentBlock = {
+							type: "toolCall",
+							id: item.call_id + "|" + item.id,
+							name: item.name,
+							arguments: {},
+							partialJson: item.arguments || "",
+						};
+						output.content.push(currentBlock);
+						stream.push({ type: "toolcall_start", contentIndex: blockIndex(), partial: output });
 					}
 				}
 				// Handle reasoning summary deltas
@@ -108,6 +120,7 @@ export const streamOpenAIResponses: GenerateFunction<"openai-responses"> = (
 							lastPart.text += event.delta;
 							stream.push({
 								type: "thinking_delta",
+								contentIndex: blockIndex(),
 								delta: event.delta,
 								partial: output,
 							});
@@ -129,6 +142,7 @@ export const streamOpenAIResponses: GenerateFunction<"openai-responses"> = (
 							lastPart.text += "\n\n";
 							stream.push({
 								type: "thinking_delta",
+								contentIndex: blockIndex(),
 								delta: "\n\n",
 								partial: output,
 							});
@@ -149,6 +163,7 @@ export const streamOpenAIResponses: GenerateFunction<"openai-responses"> = (
 							lastPart.text += event.delta;
 							stream.push({
 								type: "text_delta",
+								contentIndex: blockIndex(),
 								delta: event.delta,
 								partial: output,
 							});
@@ -162,12 +177,36 @@ export const streamOpenAIResponses: GenerateFunction<"openai-responses"> = (
 							lastPart.refusal += event.delta;
 							stream.push({
 								type: "text_delta",
+								contentIndex: blockIndex(),
 								delta: event.delta,
 								partial: output,
 							});
 						}
 					}
 				}
+				// Handle function call argument deltas
+				else if (event.type === "response.function_call_arguments.delta") {
+					if (
+						currentItem &&
+						currentItem.type === "function_call" &&
+						currentBlock &&
+						currentBlock.type === "toolCall"
+					) {
+						currentBlock.partialJson += event.delta;
+						try {
+							const args = JSON.parse(currentBlock.partialJson);
+							currentBlock.arguments = args;
+						} catch {
+							// Ignore JSON parse errors - the JSON might be incomplete
+						}
+						stream.push({
+							type: "toolcall_delta",
+							contentIndex: blockIndex(),
+							delta: event.delta,
+							partial: output,
+						});
+					}
+				}
 				// Handle output item completion
 				else if (event.type === "response.output_item.done") {
 					const item = event.item;
@@ -177,6 +216,7 @@ export const streamOpenAIResponses: GenerateFunction<"openai-responses"> = (
 						currentBlock.thinkingSignature = JSON.stringify(item);
 						stream.push({
 							type: "thinking_end",
+							contentIndex: blockIndex(),
 							content: currentBlock.thinking,
 							partial: output,
 						});
@@ -186,6 +226,7 @@ export const streamOpenAIResponses: GenerateFunction<"openai-responses"> = (
 						currentBlock.textSignature = item.id;
 						stream.push({
 							type: "text_end",
+							contentIndex: blockIndex(),
 							content: currentBlock.text,
 							partial: output,
 						});
@@ -197,8 +238,7 @@ export const streamOpenAIResponses: GenerateFunction<"openai-responses"> = (
 							name: item.name,
 							arguments: JSON.parse(item.arguments),
 						};
-						output.content.push(toolCall);
+						stream.push({ type: "toolcall_end", contentIndex: blockIndex(), toolCall, partial: output });
-						stream.push({ type: "toolCall", toolCall, partial: output });
 					}
 				}
 				// Handle completion
@@ -398,7 +438,7 @@ function convertMessages(model: Model<"openai-responses">, context: Context): Re
 			messages.push({
 				type: "function_call_output",
 				call_id: msg.toolCallId.split("|")[0],
-				output: msg.content,
+				output: msg.output,
 			});
 		}
 	}

packages/ai/src/types.ts

@@ -1,8 +1,11 @@
+import type { AssistantMessageEventStream } from "./event-stream";
 import type { AnthropicOptions } from "./providers/anthropic";
 import type { GoogleOptions } from "./providers/google";
 import type { OpenAICompletionsOptions } from "./providers/openai-completions";
 import type { OpenAIResponsesOptions } from "./providers/openai-responses";
 
+export type { AssistantMessageEventStream } from "./event-stream";
+
 export type Api = "openai-completions" | "openai-responses" | "anthropic-messages" | "google-generative-ai";
 
 export interface ApiOptionsMap {
@@ -28,12 +31,6 @@ export type Provider = KnownProvider | string;
 
 export type ReasoningEffort = "minimal" | "low" | "medium" | "high";
 
-// The stream interface - what generate() returns
-export interface GenerateStream extends AsyncIterable<AssistantMessageEvent> {
-	// Get the final message (waits for streaming to complete)
-	finalMessage(): Promise<AssistantMessage>;
-}
-
 // Base options all providers share
 export interface GenerateOptions {
 	temperature?: number;
@@ -52,7 +49,7 @@ export type GenerateFunction<TApi extends Api> = (
 	model: Model<TApi>,
 	context: Context,
 	options: OptionsForApi<TApi>,
-) => GenerateStream;
+) => AssistantMessageEventStream;
 
 export interface TextContent {
 	type: "text";
@@ -111,11 +108,12 @@ export interface AssistantMessage {
 	error?: string;
 }
 
-export interface ToolResultMessage {
+export interface ToolResultMessage<TDetails = any> {
 	role: "toolResult";
 	toolCallId: string;
 	toolName: string;
-	content: string;
+	output: string;
+	details?: TDetails;
 	isError: boolean;
 }
 
@@ -135,13 +133,15 @@ export interface Context {
 
 export type AssistantMessageEvent =
 	| { type: "start"; partial: AssistantMessage }
-	| { type: "text_start"; partial: AssistantMessage }
+	| { type: "text_start"; contentIndex: number; partial: AssistantMessage }
-	| { type: "text_delta"; delta: string; partial: AssistantMessage }
+	| { type: "text_delta"; contentIndex: number; delta: string; partial: AssistantMessage }
-	| { type: "text_end"; content: string; partial: AssistantMessage }
+	| { type: "text_end"; contentIndex: number; content: string; partial: AssistantMessage }
-	| { type: "thinking_start"; partial: AssistantMessage }
+	| { type: "thinking_start"; contentIndex: number; partial: AssistantMessage }
-	| { type: "thinking_delta"; delta: string; partial: AssistantMessage }
+	| { type: "thinking_delta"; contentIndex: number; delta: string; partial: AssistantMessage }
-	| { type: "thinking_end"; content: string; partial: AssistantMessage }
+	| { type: "thinking_end"; contentIndex: number; content: string; partial: AssistantMessage }
-	| { type: "toolCall"; toolCall: ToolCall; partial: AssistantMessage }
+	| { type: "toolcall_start"; contentIndex: number; partial: AssistantMessage }
+	| { type: "toolcall_delta"; contentIndex: number; delta: string; partial: AssistantMessage }
+	| { type: "toolcall_end"; contentIndex: number; toolCall: ToolCall; partial: AssistantMessage }
 	| { type: "done"; reason: StopReason; message: AssistantMessage }
 	| { type: "error"; error: string; partial: AssistantMessage };
 

packages/ai/test/abort.test.ts

@@ -22,7 +22,7 @@ async function testAbortSignal<TApi extends Api>(llm: Model<TApi>, options: Opti
 		abortFired = true;
 		break;
 	}
-	const msg = await response.finalMessage();
+	const msg = await response.result();
 
 	// If we get here without throwing, the abort didn't work
 	expect(msg.stopReason).toBe("error");

packages/ai/test/cross-provider-toolcall.test.ts

@@ -1,113 +0,0 @@
-import { type Context, complete, getModel } from "../src/index.js";
-
-async function testCrossProviderToolCall() {
-	console.log("Testing cross-provider tool call handoff...\n");
-
-	// Define a simple tool
-	const tools = [
-		{
-			name: "get_weather",
-			description: "Get current weather for a location",
-			parameters: {
-				type: "object",
-				properties: {
-					location: { type: "string", description: "City name" },
-				},
-				required: ["location"],
-			},
-		},
-	];
-
-	// Create context with tools
-	const context: Context = {
-		systemPrompt: "You are a helpful assistant. Use the get_weather tool when asked about weather.",
-		messages: [{ role: "user", content: "What is the weather in Paris?" }],
-		tools,
-	};
-
-	try {
-		// Step 1: Get tool call from GPT-5
-		console.log("Step 1: Getting tool call from GPT-5...");
-		const gpt5 = getModel("openai", "gpt-5-mini");
-		const gpt5Response = await complete(gpt5, context);
-		context.messages.push(gpt5Response);
-
-		// Check for tool calls
-		const toolCalls = gpt5Response.content.filter((b) => b.type === "toolCall");
-		console.log(`GPT-5 made ${toolCalls.length} tool call(s)`);
-
-		if (toolCalls.length > 0) {
-			const toolCall = toolCalls[0];
-			console.log(`Tool call ID: ${toolCall.id}`);
-			console.log(`Tool call contains pipe: ${toolCall.id.includes("|")}`);
-			console.log(`Tool: ${toolCall.name}(${JSON.stringify(toolCall.arguments)})\n`);
-
-			// Add tool result
-			context.messages.push({
-				role: "toolResult",
-				toolCallId: toolCall.id,
-				toolName: toolCall.name,
-				content: JSON.stringify({
-					location: "Paris",
-					temperature: "22°C",
-					conditions: "Partly cloudy",
-				}),
-				isError: false,
-			});
-
-			// Step 2: Send to Claude Haiku for follow-up
-			console.log("Step 2: Sending to Claude Haiku for follow-up...");
-			const haiku = getModel("anthropic", "claude-3-5-haiku-20241022");
-
-			try {
-				const haikuResponse = await complete(haiku, context);
-				console.log("✅ Claude Haiku successfully processed the conversation!");
-				console.log("Response content types:", haikuResponse.content.map((b) => b.type).join(", "));
-				console.log("Number of content blocks:", haikuResponse.content.length);
-				console.log("Stop reason:", haikuResponse.stopReason);
-				if (haikuResponse.error) {
-					console.log("Error message:", haikuResponse.error);
-				}
-
-				// Print all response content
-				for (const block of haikuResponse.content) {
-					if (block.type === "text") {
-						console.log("\nClaude text response:", block.text);
-					} else if (block.type === "thinking") {
-						console.log("\nClaude thinking:", block.thinking);
-					} else if (block.type === "toolCall") {
-						console.log("\nClaude tool call:", block.name, block.arguments);
-					}
-				}
-
-				if (haikuResponse.content.length === 0) {
-					console.log("⚠️  Claude returned an empty response!");
-				}
-			} catch (error) {
-				console.error("❌ Claude Haiku failed to process the conversation:");
-				console.error("Error:", error);
-
-				// Check if it's related to the tool call ID
-				if (error instanceof Error && error.message.includes("tool")) {
-					console.error("\n⚠️  This appears to be a tool call ID issue!");
-					console.error("The pipe character (|) in OpenAI Response API tool IDs might be causing problems.");
-				}
-			}
-		} else {
-			console.log("No tool calls were made by GPT-5");
-		}
-	} catch (error) {
-		console.error("Test failed:", error);
-	}
-}
-
-// Set API keys from environment or pass them explicitly
-const openaiKey = process.env.OPENAI_API_KEY;
-const anthropicKey = process.env.ANTHROPIC_API_KEY;
-
-if (!openaiKey || !anthropicKey) {
-	console.error("Please set OPENAI_API_KEY and ANTHROPIC_API_KEY environment variables");
-	process.exit(1);
-}
-
-testCrossProviderToolCall().catch(console.error);

packages/ai/test/generate.test.ts

@@ -5,7 +5,7 @@ import { fileURLToPath } from "url";
 import { afterAll, beforeAll, describe, expect, it } from "vitest";
 import { complete, stream } from "../src/generate.js";
 import { getModel } from "../src/models.js";
-import type { Api, Context, ImageContent, Model, OptionsForApi, Tool } from "../src/types.js";
+import type { Api, Context, ImageContent, Model, OptionsForApi, Tool, ToolResultMessage } from "../src/types.js";
 
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = dirname(__filename);
@@ -70,13 +70,62 @@ async function handleToolCall<TApi extends Api>(model: Model<TApi>, options?: Op
 		tools: [calculatorTool],
 	};
 
-	const response = await complete(model, context, options);
+	const s = await stream(model, context, options);
+	let hasToolStart = false;
+	let hasToolDelta = false;
+	let hasToolEnd = false;
+	let accumulatedToolArgs = "";
+	let index = 0;
+	for await (const event of s) {
+		if (event.type === "toolcall_start") {
+			hasToolStart = true;
+			const toolCall = event.partial.content[event.contentIndex];
+			index = event.contentIndex;
+			expect(toolCall.type).toBe("toolCall");
+			if (toolCall.type === "toolCall") {
+				expect(toolCall.name).toBe("calculator");
+				expect(toolCall.id).toBeTruthy();
+			}
+		}
+		if (event.type === "toolcall_delta") {
+			hasToolDelta = true;
+			const toolCall = event.partial.content[event.contentIndex];
+			expect(event.contentIndex).toBe(index);
+			expect(toolCall.type).toBe("toolCall");
+			if (toolCall.type === "toolCall") {
+				expect(toolCall.name).toBe("calculator");
+				accumulatedToolArgs += event.delta;
+			}
+		}
+		if (event.type === "toolcall_end") {
+			hasToolEnd = true;
+			const toolCall = event.partial.content[event.contentIndex];
+			expect(event.contentIndex).toBe(index);
+			expect(toolCall.type).toBe("toolCall");
+			if (toolCall.type === "toolCall") {
+				expect(toolCall.name).toBe("calculator");
+				JSON.parse(accumulatedToolArgs);
+				expect(toolCall.arguments).not.toBeUndefined();
+				expect((toolCall.arguments as any).a).toBe(15);
+				expect((toolCall.arguments as any).b).toBe(27);
+				expect((toolCall.arguments as any).operation).oneOf(["add", "subtract", "multiply", "divide"]);
+			}
+		}
+	}
+
+	expect(hasToolStart).toBe(true);
+	expect(hasToolDelta).toBe(true);
+	expect(hasToolEnd).toBe(true);
+
+	const response = await s.result();
 	expect(response.stopReason).toBe("toolUse");
 	expect(response.content.some((b) => b.type === "toolCall")).toBeTruthy();
 	const toolCall = response.content.find((b) => b.type === "toolCall");
 	if (toolCall && toolCall.type === "toolCall") {
 		expect(toolCall.name).toBe("calculator");
 		expect(toolCall.id).toBeTruthy();
+	} else {
+		throw new Error("No tool call found in response");
 	}
 }
 
@@ -101,7 +150,7 @@ async function handleStreaming<TApi extends Api>(model: Model<TApi>, options?: O
 		}
 	}
 
-	const response = await s.finalMessage();
+	const response = await s.result();
 
 	expect(textStarted).toBe(true);
 	expect(textChunks.length).toBeGreaterThan(0);
@@ -135,7 +184,7 @@ async function handleThinking<TApi extends Api>(model: Model<TApi>, options?: Op
 		}
 	}
 
-	const response = await s.finalMessage();
+	const response = await s.result();
 
 	expect(response.stopReason, `Error: ${response.error}`).toBe("stop");
 	expect(thinkingStarted).toBe(true);
@@ -214,6 +263,7 @@ async function multiTurn<TApi extends Api>(model: Model<TApi>, options?: Options
 		context.messages.push(response);
 
 		// Process content blocks
+		const results: ToolResultMessage[] = [];
 		for (const block of response.content) {
 			if (block.type === "text") {
 				allTextContent += block.text;
@@ -241,15 +291,16 @@ async function multiTurn<TApi extends Api>(model: Model<TApi>, options?: Options
 				}
 
 				// Add tool result to context
-				context.messages.push({
+				results.push({
 					role: "toolResult",
 					toolCallId: block.id,
 					toolName: block.name,
-					content: `${result}`,
+					output: `${result}`,
 					isError: false,
 				});
 			}
 		}
+		context.messages.push(...results);
 
 		// If we got a stop response with text content, we're likely done
 		expect(response.stopReason).not.toBe("error");
@@ -331,12 +382,12 @@ describe("Generate E2E Tests", () => {
 			await handleStreaming(llm);
 		});
 
-		it("should handle ", { retry: 2 }, async () => {
+		it("should handle thinking", { retry: 2 }, async () => {
-			await handleThinking(llm, { reasoningEffort: "medium" });
+			await handleThinking(llm, { reasoningEffort: "high" });
 		});
 
 		it("should handle multi-turn with thinking and tools", async () => {
-			await multiTurn(llm, { reasoningEffort: "medium" });
+			await multiTurn(llm, { reasoningEffort: "high" });
 		});
 
 		it("should handle image input", async () => {

packages/ai/test/handoff.test.ts

@@ -1,7 +1,7 @@
 import { describe, expect, it } from "vitest";
 import { complete } from "../src/generate.js";
 import { getModel } from "../src/models.js";
-import type { Api, AssistantMessage, Context, Message, Model, Tool } from "../src/types.js";
+import type { Api, AssistantMessage, Context, Message, Model, Tool, ToolResultMessage } from "../src/types.js";
 
 // Tool for testing
 const weatherTool: Tool = {
@@ -22,6 +22,7 @@ const providerContexts = {
 	anthropic: {
 		message: {
 			role: "assistant",
+			api: "anthropic-messages",
 			content: [
 				{
 					type: "thinking",
@@ -49,14 +50,14 @@ const providerContexts = {
 				cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
 			},
 			stopReason: "toolUse",
-		} as AssistantMessage,
+		} satisfies AssistantMessage,
 		toolResult: {
 			role: "toolResult" as const,
 			toolCallId: "toolu_01abc123",
 			toolName: "get_weather",
-			content: "Weather in Tokyo: 18°C, partly cloudy",
+			output: "Weather in Tokyo: 18°C, partly cloudy",
 			isError: false,
-		},
+		} satisfies ToolResultMessage,
 		facts: {
 			calculation: 391,
 			city: "Tokyo",
@@ -69,6 +70,7 @@ const providerContexts = {
 	google: {
 		message: {
 			role: "assistant",
+			api: "google-generative-ai",
 			content: [
 				{
 					type: "thinking",
@@ -97,14 +99,14 @@ const providerContexts = {
 				cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
 			},
 			stopReason: "toolUse",
-		} as AssistantMessage,
+		} satisfies AssistantMessage,
 		toolResult: {
 			role: "toolResult" as const,
 			toolCallId: "call_gemini_123",
 			toolName: "get_weather",
-			content: "Weather in Berlin: 22°C, sunny",
+			output: "Weather in Berlin: 22°C, sunny",
 			isError: false,
-		},
+		} satisfies ToolResultMessage,
 		facts: {
 			calculation: 456,
 			city: "Berlin",
@@ -117,6 +119,7 @@ const providerContexts = {
 	openaiCompletions: {
 		message: {
 			role: "assistant",
+			api: "openai-completions",
 			content: [
 				{
 					type: "thinking",
@@ -144,14 +147,14 @@ const providerContexts = {
 				cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
 			},
 			stopReason: "toolUse",
-		} as AssistantMessage,
+		} satisfies AssistantMessage,
 		toolResult: {
 			role: "toolResult" as const,
 			toolCallId: "call_abc123",
 			toolName: "get_weather",
-			content: "Weather in London: 15°C, rainy",
+			output: "Weather in London: 15°C, rainy",
 			isError: false,
-		},
+		} satisfies ToolResultMessage,
 		facts: {
 			calculation: 525,
 			city: "London",
@@ -164,6 +167,7 @@ const providerContexts = {
 	openaiResponses: {
 		message: {
 			role: "assistant",
+			api: "openai-responses",
 			content: [
 				{
 					type: "thinking",
@@ -193,14 +197,14 @@ const providerContexts = {
 				cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
 			},
 			stopReason: "toolUse",
-		} as AssistantMessage,
+		} satisfies AssistantMessage,
 		toolResult: {
 			role: "toolResult" as const,
 			toolCallId: "call_789_item_012", // Match the updated ID format
 			toolName: "get_weather",
-			content: "Weather in Sydney: 25°C, clear",
+			output: "Weather in Sydney: 25°C, clear",
 			isError: false,
-		},
+		} satisfies ToolResultMessage,
 		facts: {
 			calculation: 486,
 			city: "Sydney",
@@ -213,6 +217,7 @@ const providerContexts = {
 	aborted: {
 		message: {
 			role: "assistant",
+			api: "anthropic-messages",
 			content: [
 				{
 					type: "thinking",
@@ -235,7 +240,7 @@ const providerContexts = {
 			},
 			stopReason: "error",
 			error: "Request was aborted",
-		} as AssistantMessage,
+		} satisfies AssistantMessage,
 		toolResult: null,
 		facts: {
 			calculation: 600,

packages/ai/tsconfig.build.json

@@ -4,6 +4,6 @@
 		"outDir": "./dist",
 		"rootDir": "./src"
 	},
-	"include": ["src/**/*"],
+	"include": ["src/**/*.ts"],
-	"exclude": ["node_modules", "dist"]
+	"exclude": ["node_modules", "dist", "**/*.d.ts", "src/**/*.d.ts"]
 }