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| 1 | +import { |
| 2 | + type AssistantMessage, |
| 3 | + type Context, |
| 4 | + createToolResultMessage, |
| 5 | + type Message, |
| 6 | + type StreamOptions, |
| 7 | +} from '@agentic-kit/core'; |
| 8 | +import { stream as defaultStream } from 'agentic-kit'; |
| 9 | + |
| 10 | +import type { |
| 11 | + AgentEvent, |
| 12 | + AgentOptions, |
| 13 | + AgentState, |
| 14 | + AgentTool, |
| 15 | + AgentToolResult, |
| 16 | +} from './types.js'; |
| 17 | +import { validateToolArguments as defaultValidateToolArguments } from './validation.js'; |
| 18 | + |
| 19 | +export type AgentEventSink = (event: AgentEvent) => void | Promise<void>; |
| 20 | + |
| 21 | +export type AgentLoopConfig = { |
| 22 | + initialMessages?: Message[]; |
| 23 | + state: AgentState; |
| 24 | + streamFn?: AgentOptions['streamFn']; |
| 25 | + transformContext?: AgentOptions['transformContext']; |
| 26 | + validateToolArguments?: AgentOptions['validateToolArguments']; |
| 27 | + signal: AbortSignal; |
| 28 | +}; |
| 29 | + |
| 30 | +export async function runAgentLoop(config: AgentLoopConfig, emit: AgentEventSink): Promise<Message[]> { |
| 31 | + const messages = [...config.state.messages]; |
| 32 | + |
| 33 | + await emit({ type: 'agent_start' }); |
| 34 | + |
| 35 | + if (config.initialMessages && config.initialMessages.length > 0) { |
| 36 | + for (const message of config.initialMessages) { |
| 37 | + await emit({ type: 'message_start', message }); |
| 38 | + messages.push(message); |
| 39 | + await emit({ type: 'message_end', message }); |
| 40 | + } |
| 41 | + } |
| 42 | + |
| 43 | + while (true) { |
| 44 | + await emit({ type: 'turn_start' }); |
| 45 | + |
| 46 | + const assistantMessage = await generateAssistantMessage(config, messages, emit); |
| 47 | + messages.push(assistantMessage); |
| 48 | + await emit({ type: 'message_end', message: assistantMessage }); |
| 49 | + |
| 50 | + if (assistantMessage.stopReason === 'error' || assistantMessage.stopReason === 'aborted') { |
| 51 | + await emit({ type: 'turn_end', message: assistantMessage, toolResults: [] }); |
| 52 | + break; |
| 53 | + } |
| 54 | + |
| 55 | + const toolCalls = assistantMessage.content.filter((block) => block.type === 'toolCall'); |
| 56 | + if (toolCalls.length === 0) { |
| 57 | + await emit({ type: 'turn_end', message: assistantMessage, toolResults: [] }); |
| 58 | + break; |
| 59 | + } |
| 60 | + |
| 61 | + const toolResults = await executeToolCalls(config, toolCalls, emit); |
| 62 | + for (const toolResult of toolResults) { |
| 63 | + await emit({ type: 'message_start', message: toolResult }); |
| 64 | + messages.push(toolResult); |
| 65 | + await emit({ type: 'message_end', message: toolResult }); |
| 66 | + } |
| 67 | + |
| 68 | + await emit({ type: 'turn_end', message: assistantMessage, toolResults }); |
| 69 | + } |
| 70 | + |
| 71 | + await emit({ type: 'agent_end', messages }); |
| 72 | + return messages; |
| 73 | +} |
| 74 | + |
| 75 | +async function generateAssistantMessage( |
| 76 | + config: AgentLoopConfig, |
| 77 | + messages: Message[], |
| 78 | + emit: AgentEventSink |
| 79 | +): Promise<AssistantMessage> { |
| 80 | + const transformedMessages = config.transformContext |
| 81 | + ? await config.transformContext(messages, config.signal) |
| 82 | + : messages; |
| 83 | + |
| 84 | + const context: Context = { |
| 85 | + systemPrompt: config.state.systemPrompt, |
| 86 | + tools: config.state.tools, |
| 87 | + messages: transformedMessages, |
| 88 | + }; |
| 89 | + |
| 90 | + const streamFn = config.streamFn ?? defaultStream; |
| 91 | + const streamResult = streamFn(config.state.model, context, { |
| 92 | + ...(config.state.streamOptions ?? {}), |
| 93 | + signal: config.signal, |
| 94 | + } as StreamOptions); |
| 95 | + |
| 96 | + for await (const event of streamResult) { |
| 97 | + switch (event.type) { |
| 98 | + case 'start': |
| 99 | + await emit({ type: 'message_start', message: event.partial }); |
| 100 | + break; |
| 101 | + case 'text_start': |
| 102 | + case 'text_delta': |
| 103 | + case 'text_end': |
| 104 | + case 'thinking_start': |
| 105 | + case 'thinking_delta': |
| 106 | + case 'thinking_end': |
| 107 | + case 'toolcall_start': |
| 108 | + case 'toolcall_delta': |
| 109 | + case 'toolcall_end': |
| 110 | + await emit({ |
| 111 | + type: 'message_update', |
| 112 | + message: event.partial, |
| 113 | + assistantMessageEvent: event, |
| 114 | + }); |
| 115 | + break; |
| 116 | + case 'done': |
| 117 | + case 'error': |
| 118 | + break; |
| 119 | + } |
| 120 | + } |
| 121 | + |
| 122 | + return streamResult.result(); |
| 123 | +} |
| 124 | + |
| 125 | +async function executeToolCalls( |
| 126 | + config: AgentLoopConfig, |
| 127 | + toolCalls: Array<Extract<AssistantMessage['content'][number], { type: 'toolCall' }>>, |
| 128 | + emit: AgentEventSink |
| 129 | +) { |
| 130 | + const results = []; |
| 131 | + |
| 132 | + for (const toolCall of toolCalls) { |
| 133 | + const tool = config.state.tools.find((candidate) => candidate.name === toolCall.name); |
| 134 | + await emit({ |
| 135 | + type: 'tool_execution_start', |
| 136 | + toolCallId: toolCall.id, |
| 137 | + toolName: toolCall.name, |
| 138 | + args: toolCall.arguments as Record<string, unknown>, |
| 139 | + }); |
| 140 | + |
| 141 | + let result: AgentToolResult; |
| 142 | + let isError = false; |
| 143 | + |
| 144 | + try { |
| 145 | + if (!tool) { |
| 146 | + throw new Error(`Tool '${toolCall.name}' not found`); |
| 147 | + } |
| 148 | + |
| 149 | + const validateToolArguments = config.validateToolArguments ?? defaultValidateToolArguments; |
| 150 | + const validatedArgs = validateToolArguments( |
| 151 | + tool.parameters, |
| 152 | + toolCall.arguments as Record<string, unknown> |
| 153 | + ); |
| 154 | + |
| 155 | + result = await executeTool(tool, toolCall.id, validatedArgs, config.signal, emit); |
| 156 | + } catch (error) { |
| 157 | + result = { |
| 158 | + content: [ |
| 159 | + { |
| 160 | + type: 'text', |
| 161 | + text: error instanceof Error ? error.message : String(error), |
| 162 | + }, |
| 163 | + ], |
| 164 | + }; |
| 165 | + isError = true; |
| 166 | + } |
| 167 | + |
| 168 | + await emit({ |
| 169 | + type: 'tool_execution_end', |
| 170 | + toolCallId: toolCall.id, |
| 171 | + toolName: toolCall.name, |
| 172 | + result, |
| 173 | + isError, |
| 174 | + }); |
| 175 | + |
| 176 | + results.push( |
| 177 | + createToolResultMessage(toolCall.id, toolCall.name, result.content, isError) |
| 178 | + ); |
| 179 | + } |
| 180 | + |
| 181 | + return results; |
| 182 | +} |
| 183 | + |
| 184 | +async function executeTool( |
| 185 | + tool: AgentTool, |
| 186 | + toolCallId: string, |
| 187 | + args: Record<string, unknown>, |
| 188 | + signal: AbortSignal, |
| 189 | + emit: AgentEventSink |
| 190 | +): Promise<AgentToolResult> { |
| 191 | + const updateEvents: Promise<void>[] = []; |
| 192 | + |
| 193 | + try { |
| 194 | + return await tool.execute(toolCallId, args, signal, (partialResult) => { |
| 195 | + updateEvents.push( |
| 196 | + Promise.resolve( |
| 197 | + emit({ |
| 198 | + type: 'tool_execution_update', |
| 199 | + toolCallId, |
| 200 | + toolName: tool.name, |
| 201 | + args, |
| 202 | + partialResult, |
| 203 | + }) |
| 204 | + ) |
| 205 | + ); |
| 206 | + }); |
| 207 | + } finally { |
| 208 | + await Promise.all(updateEvents); |
| 209 | + } |
| 210 | +} |
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