feat: support R2 image attachments in agent conversations

src/storage/r2-public-file.service.spec.ts

@@ -2,6 +2,23 @@ import { ConfigService } from '@nestjs/config';
 import { R2PublicFileService } from './r2-public-file.service';
 
 describe('R2 direct upload URL', () => {
+  it('bounds image object reads and closes streams on oversized responses', async () => {
+    const service = new R2PublicFileService(new ConfigService({ R2_BUCKET: 'test', R2_PUBLIC_BASE_URL: 'https://files.test', R2_ACCESS_KEY_ID: 'test', R2_SECRET_ACCESS_KEY: 'test' }));
+    const body = { async *[Symbol.asyncIterator]() { yield Buffer.from('12'); yield Buffer.from('34'); }, destroy: jest.fn() };
+    const send = jest.fn().mockResolvedValue({ ContentLength: 4, Body: body });
+    (service as unknown as { client: unknown }).client = { send };
+    expect(await service.readPublicFile('studio-files/public/image.png', 4)).toEqual(Buffer.from('1234'));
+    expect(body.destroy).toHaveBeenCalledTimes(1);
+    send.mockResolvedValueOnce({ ContentLength: 100, Body: body });
+    await expect(service.readPublicFile('studio-files/public/image.png', 4)).rejects.toThrow(/크기/);
+    expect(body.destroy).toHaveBeenCalledTimes(2);
+    send.mockResolvedValueOnce({ ContentLength: 2, Body: body });
+    await expect(service.readPublicFile('studio-files/public/image.png', 3)).rejects.toThrow(/크기/);
+    expect(body.destroy).toHaveBeenCalledTimes(3);
+    await expect(service.readPublicFile('private/image.png', 4)).rejects.toThrow();
+    expect(send).toHaveBeenCalledTimes(3);
+  });
+
   it('signs a PUT without a checksum for an empty body', async () => {
     const service = new R2PublicFileService(new ConfigService({
       R2_BUCKET: 'test', R2_ACCOUNT_ID: 'test',

src/storage/r2-public-file.service.ts

@@ -1,4 +1,4 @@
-import { DeleteObjectCommand, HeadObjectCommand, PutObjectCommand, S3Client } from '@aws-sdk/client-s3';
+import { DeleteObjectCommand, GetObjectCommand, HeadObjectCommand, PutObjectCommand, S3Client } from '@aws-sdk/client-s3';
 import { getSignedUrl } from '@aws-sdk/s3-request-presigner';
 import { Injectable } from '@nestjs/common';
 import { ConfigService } from '@nestjs/config';
@@ -79,6 +79,29 @@ export class R2PublicFileService {
     return this.publicUrl(input.key);
   }
 
+  createLmsAgentImageKey(input: { courseId: string; userId: string; imageId: string }) {
+    return [this.publicPrefix, 'lms', 'agent-attachments', input.courseId, input.userId, `${input.imageId}.png`].join('/');
+  }
+
+  async readPublicFile(key: string, maxBytes: number): Promise<Buffer> {
+    if (!this.isConfigured() || !this.isPublicKey(key)) throw new Error('이미지 저장소가 설정되지 않았습니다.');
+    const result = await this.getClient().send(new GetObjectCommand({ Bucket: this.bucket, Key: key }));
+    if (!result.Body) throw new Error('첨부 이미지를 찾을 수 없습니다.');
+    const chunks: Buffer[] = [];
+    let bytes = 0;
+    try {
+      if ((result.ContentLength ?? maxBytes + 1) > maxBytes) throw new Error('첨부 이미지 크기가 올바르지 않습니다.');
+      for await (const chunk of result.Body as AsyncIterable<Uint8Array>) {
+        bytes += chunk.length;
+        if (bytes > maxBytes) throw new Error('첨부 이미지 크기가 올바르지 않습니다.');
+        chunks.push(Buffer.from(chunk));
+      }
+      return Buffer.concat(chunks);
+    } finally {
+      if ('destroy' in result.Body && typeof result.Body.destroy === 'function') result.Body.destroy();
+    }
+  }
+
   async deletePublicFile(key: string) {
     if (!this.isConfigured() || !this.isPublicKey(key)) return;