fix: harden real backend workflows and channel connections

api/src/files/files.service.ts

@@ -1,4 +1,4 @@
-import { Injectable } from '@nestjs/common';
+import { Injectable, NotFoundException } from '@nestjs/common';
 import { Prisma } from '@prisma/client';
 import { randomUUID } from 'node:crypto';
 import { PrismaService } from '../prisma/prisma.service';
@@ -38,7 +38,7 @@ export class FilesService {
       where: tenantId ? { tenantId } : undefined,
       orderBy: { createdAt: 'desc' },
       take: 100,
-    });
+    }).then((items) => items.map(serializeFileObject));
   }
 
   create(data: CreateFileObjectDto) {
@@ -52,7 +52,7 @@ export class FilesService {
       checksum: data.checksum,
       purpose: data.purpose,
     };
-    return this.prisma.fileObject.create({ data: createData });
+    return this.prisma.fileObject.create({ data: createData }).then(serializeFileObject);
   }
 
   async createPresignedUpload(data: CreatePresignedUploadDto) {
@@ -79,4 +79,23 @@ export class FilesService {
       purpose: data.purpose,
     });
   }
+
+  async getDownload(id: string) {
+    const fileObject = await this.prisma.fileObject.findUnique({ where: { id } });
+    if (!fileObject) {
+      throw new NotFoundException('File object not found');
+    }
+    const content = await this.objectStorage.getObject(fileObject.objectKey);
+    return {
+      fileObject: serializeFileObject(fileObject),
+      content,
+    };
+  }
+}
+
+function serializeFileObject<T extends { sizeBytes: bigint | number | string }>(fileObject: T) {
+  return {
+    ...fileObject,
+    sizeBytes: fileObject.sizeBytes.toString(),
+  };
 }