136 lines
5.2 KiB
TypeScript
136 lines
5.2 KiB
TypeScript
/**
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* 上下文构建（任务 A3.8，实施设计 1.3 / 1.5）。
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*
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* 目标：不把整段会话塞给模型。按预算取「最近若干轮 + 滚动摘要 + 钉住的引用」，
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* 工具执行只以引用形式进摘要（能力、状态、参数摘要、executionId），需要细节时再调能力取回。
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*
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* 三条约束：
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* 1. 摘要与原始消息都留在平台：摘要条目带来源消息 id，任何结论都能追回原文
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* 2. 构建是确定性的、可测的：这里不调模型（真正的模型摘要等 A4 之后按需替换）
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* 3. 引擎只拿到「上下文包」，不拿所有权（架构设计 5.1 固定点：状态归平台）
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*/
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import type { ChatMessage } from '@aps/contracts';
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export interface ContextBudget {
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/** 上下文包总字符预算（粗略按字符算，够用且不引入 tokenizer 依赖） */
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maxChars: number;
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/** 至少保留的最近消息条数 */
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recentMessages: number;
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/** 摘要部分最多占多少字符 */
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summaryMaxChars: number;
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/** 摘要里最多引用多少条执行记录 */
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recentExecutions: number;
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}
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export const DEFAULT_CONTEXT_BUDGET: ContextBudget = {
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maxChars: 6000,
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recentMessages: 6,
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summaryMaxChars: 1800,
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recentExecutions: 6,
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};
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/** 执行记录的引用（来自 Core，不进历史原文） */
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export interface ExecutionReference {
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capabilityId: string;
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status: string;
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executionId: string;
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paramsDigest: string;
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createdAt: number;
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}
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export interface ContextBuildInput {
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messages: ChatMessage[];
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executions?: ExecutionReference[];
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/** 用户钉住的消息：无论多早都保留（界面在 A10.4 提供入口） */
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pinnedMessageIds?: string[];
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budget?: Partial<ContextBudget>;
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}
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export interface ContextBuildResult {
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/** 注入给引擎的上下文包；空串表示无需注入（例如会话刚开始） */
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prefix: string;
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/** 存进检查点的摘要（含来源消息 id，便于追溯） */
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summary: string;
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/** 摘要引用的消息 id */
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summarySourceIds: string[];
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/** 原样保留的最近消息 id */
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includedMessageIds: string[];
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/** 因预算被折叠进摘要之前的消息（原文仍在平台，未丢失） */
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droppedMessageIds: string[];
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estimatedChars: number;
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}
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const clip = (text: string, max: number): string => (text.length <= max ? text : `${text.slice(0, max)}…（已截断）`);
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const roleLabel = (role: ChatMessage['role']): string => (role === 'user' ? '用户' : role === 'assistant' ? '助手' : '系统');
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function renderExecution(reference: ExecutionReference): string {
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return `- 调用 ${reference.capabilityId} → ${reference.status}（${reference.executionId}，参数摘要 ${reference.paramsDigest}）`;
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}
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export function buildContext(input: ContextBuildInput): ContextBuildResult {
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const budget: ContextBudget = { ...DEFAULT_CONTEXT_BUDGET, ...(input.budget ?? {}) };
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const messages = input.messages;
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const pinned = new Set(input.pinnedMessageIds ?? []);
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const kept: ChatMessage[] = [];
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const dropped: ChatMessage[] = [];
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let usedChars = 0;
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// 从最近往前收：先保证「最近若干轮」，再按预算继续吃历史
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for (let index = messages.length - 1; index >= 0; index -= 1) {
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const message = messages[index];
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if (!message) continue;
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const cost = message.text.length + 12;
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const isRecent = messages.length - index <= budget.recentMessages;
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const mustKeep = isRecent || pinned.has(message.messageId);
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if (mustKeep || usedChars + cost <= budget.maxChars) {
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kept.unshift(message);
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usedChars += cost;
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} else {
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dropped.unshift(message);
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}
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}
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// 摘要：折叠掉的消息取要点（保留前 80 字），附来源 id
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const summaryLines: string[] = [];
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let summaryChars = 0;
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for (const message of dropped) {
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const line = `- ${roleLabel(message.role)}（${message.messageId}）：${clip(message.text.replace(/\s+/g, ' '), 80)}`;
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if (summaryChars + line.length > budget.summaryMaxChars) {
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summaryLines.push(`- ……另有 ${dropped.length - summaryLines.length} 条更早的消息，原始内容保留在平台会话记录里`);
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break;
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}
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summaryLines.push(line);
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summaryChars += line.length;
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}
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const executionLines = (input.executions ?? [])
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.slice(0, budget.recentExecutions)
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.map(renderExecution);
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const blocks: string[] = [];
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if (summaryLines.length > 0 || executionLines.length > 0) {
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blocks.push('【此前对话的摘要】');
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blocks.push(...summaryLines);
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if (executionLines.length > 0) {
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blocks.push('【相关工具执行（只给引用，需要细节请调对应能力）】');
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blocks.push(...executionLines);
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}
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}
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if (kept.length > 0) {
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blocks.push('【最近的对话】');
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for (const message of kept) blocks.push(`${roleLabel(message.role)}：${message.text}`);
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}
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const prefix = blocks.length === 0 ? '' : `${blocks.join('\n')}\n【以上是背景，以下是用户这次的问题】\n`;
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const summary = summaryLines.join('\n');
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return {
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prefix,
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summary,
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summarySourceIds: dropped.map((message) => message.messageId),
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includedMessageIds: kept.map((message) => message.messageId),
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droppedMessageIds: dropped.map((message) => message.messageId),
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estimatedChars: prefix.length,
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};
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} |