Cloudflareでコンテンツエージェントを動かす最安コスト分析

HTTPトリガー（cronまたはwebhook）
        │
        ▼
  Worker: オーケストレーター
        │
        ├─ ジョブメタデータをKVに書き込む（ステータス: "pending"）
        │
        └─ ENジョブ1件をキューに積む
               │
               ▼
         キュー: content-jobs
               │
        ┌──────┴──────┐
        ▼             ▼
  Worker: ライター   Worker: トランスレーター（×12ロケール）
        │                    │
        ▼                    ▼
  Claude API             Claude API
        │                    │
        └──────┬─────────────┘
               ▼
        KV: posts/{slug}/{locale}
               │
               ▼
     Webhook → GitHub → デプロイ

// src/workers/orchestrator.ts
import { Queue } from "@cloudflare/workers-types";

interface Env {
  CONTENT_QUEUE: Queue;
  POSTS_KV: KVNamespace;
}

export default {
  async fetch(request: Request, env: Env): Promise<Response> {
    const { slug, topic } = await request.json<{ slug: string; topic: string }>();

    // 初期ステータスを書き込む
    await env.POSTS_KV.put(
      `status:${slug}`,
      JSON.stringify({ status: "pending", createdAt: Date.now() })
    );

    // EN生成ジョブをキューに積む
    await env.CONTENT_QUEUE.send({
      type: "generate",
      slug,
      topic,
      locale: "en",
    });

    return Response.json({ queued: true, slug });
  },
};

// src/workers/content-processor.ts
interface Env {
  CONTENT_QUEUE: Queue;
  POSTS_KV: KVNamespace;
  ANTHROPIC_API_KEY: string;
}

const LOCALES = ["ar","de","es","fr","hi","it","ja","ko","nl","pt","ru","zh"];

export default {
  async queue(batch: MessageBatch<ContentJob>, env: Env): Promise<void> {
    for (const msg of batch.messages) {
      const job = msg.body;

      if (job.type === "generate") {
        const post = await generatePost(job.topic, env.ANTHROPIC_API_KEY);
        await env.POSTS_KV.put(`post:${job.slug}:en`, post);

        // 翻訳をファンアウト
        for (const locale of LOCALES) {
          await env.CONTENT_QUEUE.send({
            type: "translate",
            slug: job.slug,
            locale,
            sourceText: post,
          });
        }
      }

      if (job.type === "translate") {
        const translated = await translatePost(
          job.sourceText,
          job.locale,
          env.ANTHROPIC_API_KEY,
          // コスト削減のため翻訳にはHaikuを使用
          "claude-haiku-3-5-20241022"
        );
        await env.POSTS_KV.put(`post:${job.slug}:${job.locale}`, translated);
      }

      msg.ack();
    }
  },
};

async function generatePost(topic: string, apiKey: string): Promise<string> {
  const res = await fetch("https://api.anthropic.com/v1/messages", {
    method: "POST",
    headers: {
      "x-api-key": apiKey,
      "anthropic-version": "2023-06-01",
      "content-type": "application/json",
    },
    body: JSON.stringify({
      model: "claude-sonnet-3-5-20241022",
      max_tokens: 4096,
      messages: [{ role: "user", content: `Write a detailed blog post about: ${topic}` }],
    }),
  });
  const data = await res.json<{ content: Array<{ text: string }> }>();
  return data.content[0].text;
}

async function translatePost(
  text: string,
  locale: string,
  apiKey: string,
  model: string
): Promise<string> {
  const res = await fetch("https://api.anthropic.com/v1/messages", {
    method: "POST",
    headers: {
      "x-api-key": apiKey,
      "anthropic-version": "2023-06-01",
      "content-type": "application/json",
    },
    body: JSON.stringify({
      model,
      max_tokens: 4096,
      messages: [
        {
          role: "user",
          content: `Translate the following blog post to ${locale}. Preserve all markdown. Keep code blocks in English.\n\n${text}`,
        },
      ],
    }),
  });
  const data = await res.json<{ content: Array<{ text: string }> }>();
  return data.content[0].text;
}

// ジョブステータス
await kv.put(`status:${slug}`, JSON.stringify({ status, updatedAt: Date.now() }));

// 記事コンテンツ
await kv.put(`post:${slug}:${locale}`, markdownContent);

// 一覧用インデックス
const index = await kv.get<string[]>("index:posts", "json") ?? [];
await kv.put("index:posts", JSON.stringify([...index, slug]));