feat: migrate runtime backend to node server

2026-04-08 16:41:29 +08:00
parent 9d2fc9e4b8
commit a83841ff2d
70 changed files with 8239 additions and 1561 deletions
--- a/server-node/src/services/llmClient.ts
+++ b/server-node/src/services/llmClient.ts
@@ -0,0 +1,169 @@
+import { Readable } from 'node:stream';
+
+import type { Response as ExpressResponse } from 'express';
+import type { Logger } from 'pino';
+
+import type { AppConfig } from '../config.js';
+import { upstreamError } from '../errors.js';
+import { extractApiErrorMessage } from '../http.js';
+
+export type ChatMessage = {
+  role: 'system' | 'user' | 'assistant';
+  content: string;
+};
+
+type CompletionRequest = {
+  model?: string;
+  stream?: boolean;
+  messages: ChatMessage[];
+};
+
+function normalizeBaseUrl(baseUrl: string) {
+  return baseUrl.replace(/\/+$/u, '');
+}
+
+function buildCompletionUrl(baseUrl: string) {
+  return `${normalizeBaseUrl(baseUrl)}/chat/completions`;
+}
+
+export class UpstreamLlmClient {
+  constructor(
+    private readonly config: AppConfig,
+    private readonly logger: Logger,
+  ) {}
+
+  private resolveModel(model?: string) {
+    return model?.trim() || this.config.llm.model;
+  }
+
+  private buildHeaders() {
+    if (!this.config.llm.apiKey) {
+      throw upstreamError('服务端缺少 LLM_API_KEY');
+    }
+
+    return {
+      Authorization: `Bearer ${this.config.llm.apiKey}`,
+      'Content-Type': 'application/json',
+    };
+  }
+
+  async requestCompletion(body: CompletionRequest, signal?: AbortSignal) {
+    const response = await fetch(buildCompletionUrl(this.config.llm.baseUrl), {
+      method: 'POST',
+      headers: this.buildHeaders(),
+      body: JSON.stringify({
+        ...body,
+        model: this.resolveModel(body.model),
+      }),
+      signal,
+    });
+
+    if (!response.ok) {
+      const rawText = await response.text();
+      throw upstreamError(
+        extractApiErrorMessage(rawText, 'LLM 上游请求失败'),
+      );
+    }
+
+    return response;
+  }
+
+  async requestMessageContent(params: {
+    systemPrompt: string;
+    userPrompt: string;
+    model?: string;
+    signal?: AbortSignal;
+  }) {
+    const response = await this.requestCompletion(
+      {
+        model: params.model,
+        messages: [
+          { role: 'system', content: params.systemPrompt },
+          { role: 'user', content: params.userPrompt },
+        ],
+      },
+      params.signal,
+    );
+    const rawText = await response.text();
+    const parsed = JSON.parse(rawText) as {
+      choices?: Array<{
+        message?: {
+          content?: string;
+        };
+      }>;
+    };
+    const content = parsed.choices?.[0]?.message?.content?.trim();
+
+    if (!content) {
+      throw upstreamError('LLM 返回内容为空');
+    }
+
+    return content;
+  }
+
+  async forwardCompletion(body: Record<string, unknown>, response: ExpressResponse) {
+    const upstreamResponse = await fetch(buildCompletionUrl(this.config.llm.baseUrl), {
+      method: 'POST',
+      headers: this.buildHeaders(),
+      body: JSON.stringify({
+        ...body,
+        model:
+          typeof body.model === 'string' && body.model.trim()
+            ? body.model
+            : this.config.llm.model,
+      }),
+    });
+
+    if (!upstreamResponse.ok) {
+      const rawText = await upstreamResponse.text();
+      throw upstreamError(
+        extractApiErrorMessage(rawText, 'LLM 上游请求失败'),
+      );
+    }
+
+    response.status(upstreamResponse.status);
+    response.setHeader(
+      'Content-Type',
+      upstreamResponse.headers.get('content-type') || 'application/json; charset=utf-8',
+    );
+
+    if (!upstreamResponse.body) {
+      response.end();
+      return;
+    }
+
+    await Readable.fromWeb(upstreamResponse.body as never).pipe(response);
+  }
+
+  async forwardSseText(params: {
+    systemPrompt: string;
+    userPrompt: string;
+    response: ExpressResponse;
+    model?: string;
+  }) {
+    const upstreamResponse = await this.requestCompletion({
+      model: params.model,
+      stream: true,
+      messages: [
+        { role: 'system', content: params.systemPrompt },
+        { role: 'user', content: params.userPrompt },
+      ],
+    });
+
+    params.response.status(upstreamResponse.status);
+    params.response.setHeader(
+      'Content-Type',
+      upstreamResponse.headers.get('content-type') || 'text/event-stream; charset=utf-8',
+    );
+    params.response.setHeader('Cache-Control', 'no-cache');
+    params.response.setHeader('Connection', 'keep-alive');
+    params.response.setHeader('X-Accel-Buffering', 'no');
+
+    if (!upstreamResponse.body) {
+      params.response.end();
+      return;
+    }
+
+    await Readable.fromWeb(upstreamResponse.body as never).pipe(params.response);
+  }
+}