feat: implement chunked storage for Telegram file uploads and retrieval

src/db/file-parts.ts

@@ -0,0 +1,97 @@
+import { sql } from 'drizzle-orm';
+import { db } from './index';
+
+export type CompressionAlgorithm = 'gzip' | null;
+
+export interface FilePart {
+  id: number;
+  fileId: string;
+  partNumber: number;
+  telegramFileId: string;
+  telegramFileUniqueId: string;
+  storageChatId: number;
+  storageMessageId: number;
+  sizeBytes: number;
+  storedSizeBytes: number;
+  compressionAlgorithm: CompressionAlgorithm;
+  etag: string;
+  createdAt: Date;
+}
+
+export type NewFilePartInput = Omit<FilePart, 'id' | 'createdAt'>;
+
+const toNumber = (value: unknown): number => Number(value ?? 0);
+
+const mapRowToFilePart = (row: Record<string, unknown>): FilePart => ({
+  id: toNumber(row.id),
+  fileId: row.file_id as string,
+  partNumber: toNumber(row.part_number),
+  telegramFileId: row.telegram_file_id as string,
+  telegramFileUniqueId: row.telegram_file_unique_id as string,
+  storageChatId: toNumber(row.storage_chat_id),
+  storageMessageId: toNumber(row.storage_message_id),
+  sizeBytes: toNumber(row.size_bytes),
+  storedSizeBytes: toNumber(row.stored_size_bytes),
+  compressionAlgorithm: (row.compression_algorithm as CompressionAlgorithm) || null,
+  etag: row.etag as string,
+  createdAt: new Date(row.created_at as string),
+});
+
+export const insertFileParts = async (parts: NewFilePartInput[]): Promise<void> => {
+  for (const part of parts) {
+    await db.execute(
+      sql`INSERT INTO file_parts (
+        file_id,
+        part_number,
+        telegram_file_id,
+        telegram_file_unique_id,
+        storage_chat_id,
+        storage_message_id,
+        size_bytes,
+        stored_size_bytes,
+        compression_algorithm,
+        etag
+      ) VALUES (
+        ${part.fileId}::uuid,
+        ${part.partNumber},
+        ${part.telegramFileId},
+        ${part.telegramFileUniqueId},
+        ${part.storageChatId},
+        ${part.storageMessageId},
+        ${part.sizeBytes},
+        ${part.storedSizeBytes},
+        ${part.compressionAlgorithm},
+        ${part.etag}
+      )`,
+    );
+  }
+};
+
+export const listFileParts = async (fileId: string): Promise<FilePart[]> => {
+  const result = (await db.execute(
+    sql`SELECT id,
+      file_id,
+      part_number,
+      telegram_file_id,
+      telegram_file_unique_id,
+      storage_chat_id,
+      storage_message_id,
+      size_bytes,
+      stored_size_bytes,
+      compression_algorithm,
+      etag,
+      created_at
+    FROM file_parts
+    WHERE file_id = ${fileId}::uuid
+    ORDER BY part_number`,
+  )) as unknown as Record<string, unknown>[];
+
+  return result.map(mapRowToFilePart);
+};
+
+export const countFileParts = async (fileId: string): Promise<number> => {
+  const result = (await db.execute(
+    sql`SELECT COUNT(*) AS count FROM file_parts WHERE file_id = ${fileId}::uuid`,
+  )) as unknown as Record<string, unknown>[];
+  return toNumber(result[0]?.count);
+};

src/db/files-ext.ts

@@ -51,6 +51,8 @@ const mapDbRowToS3Record = (row: Record<string, unknown>): S3FileRecord => {
     storageBackend: (row.storage_backend as string) || 'telegram',
     isDeleted: row.is_deleted as boolean,
     multipartUploadId: row.multipart_upload_id as string | null,
+    partCount:
+      row.part_count === null || row.part_count === undefined ? null : toNumber(row.part_count),
     createdAt: new Date(row.created_at as string),
     updatedAt: new Date(row.updated_at as string),
   };

src/db/index.ts

@@ -1,6 +1,6 @@
 import { drizzle } from 'drizzle-orm/postgres-js';
 import postgres from 'postgres';
-import { files } from './schema';
+import { fileParts, files } from './schema';
 
 const client = postgres(process.env.DATABASE_URL!, {
   max: 10,
@@ -8,6 +8,6 @@ const client = postgres(process.env.DATABASE_URL!, {
   connect_timeout: 10,
 });
 
-export const db = drizzle(client, { schema: { files } });
-export { files };
+export const db = drizzle(client, { schema: { fileParts, files } });
+export { fileParts, files };
 export default db;

src/db/schema.ts

@@ -1,5 +1,14 @@
 import type { InferInsertModel, InferSelectModel } from 'drizzle-orm';
-import { bigint, boolean, pgTable, text, timestamp, uuid } from 'drizzle-orm/pg-core';
+import {
+  bigint,
+  boolean,
+  integer,
+  pgTable,
+  serial,
+  text,
+  timestamp,
+  uuid,
+} from 'drizzle-orm/pg-core';
 
 export const files = pgTable('files', {
   id: uuid('id').primaryKey().defaultRandom(),
@@ -25,9 +34,27 @@ export const files = pgTable('files', {
   storageBackend: text('storage_backend').default('telegram'),
   isDeleted: boolean('is_deleted').default(false),
   multipartUploadId: text('multipart_upload_id'),
+  partCount: integer('part_count'),
   createdAt: timestamp('created_at').defaultNow().notNull(),
   updatedAt: timestamp('updated_at').defaultNow().notNull(),
 });
 
+export const fileParts = pgTable('file_parts', {
+  id: serial('id').primaryKey(),
+  fileId: uuid('file_id').notNull(),
+  partNumber: integer('part_number').notNull(),
+  telegramFileId: text('telegram_file_id').notNull(),
+  telegramFileUniqueId: text('telegram_file_unique_id').notNull(),
+  storageChatId: bigint('storage_chat_id', { mode: 'number' }).notNull(),
+  storageMessageId: bigint('storage_message_id', { mode: 'number' }).notNull(),
+  sizeBytes: bigint('size_bytes', { mode: 'number' }).notNull(),
+  storedSizeBytes: bigint('stored_size_bytes', { mode: 'number' }).notNull(),
+  compressionAlgorithm: text('compression_algorithm'),
+  etag: text('etag').notNull(),
+  createdAt: timestamp('created_at').defaultNow().notNull(),
+});
+
 export type File = InferSelectModel<typeof files>;
 export type NewFile = InferInsertModel<typeof files>;
+export type FilePart = InferSelectModel<typeof fileParts>;
+export type NewFilePart = InferInsertModel<typeof fileParts>;

src/env.ts

@@ -16,6 +16,9 @@ interface AppConfig {
   batchMaxItems: number;
   batchMaxSizeBytes: number;
   maxRequestBodyBytes: number;
+  telegramChunkSizeBytes: number;
+  compressChunkedUploads: boolean;
+  chunkCompressionMinSizeBytes: number;
   s3AccessKey: string;
   s3SecretKey: string;
   s3DefaultRegion: string;
@@ -85,6 +88,9 @@ export const config: AppConfig = {
   batchMaxItems: parseNumber(process.env.BATCH_MAX_ITEMS, 20),
   batchMaxSizeBytes: parseNumber(process.env.BATCH_MAX_SIZE_BYTES, 500 * 1024 * 1024),
   maxRequestBodyBytes: parseNumber(process.env.MAX_REQUEST_BODY_BYTES, 2 * 1024 * 1024 * 1024),
+  telegramChunkSizeBytes: parseNumber(process.env.TELEGRAM_CHUNK_SIZE_BYTES, 20 * 1024 * 1024),
+  compressChunkedUploads: process.env.COMPRESS_CHUNKED_UPLOADS !== 'false',
+  chunkCompressionMinSizeBytes: parseNumber(process.env.CHUNK_COMPRESSION_MIN_SIZE_BYTES, 4096),
   s3AccessKey: process.env.S3_ACCESS_KEY || 'teleuploader-admin',
   s3SecretKey: process.env.S3_SECRET_KEY || '',
   s3DefaultRegion: process.env.S3_DEFAULT_REGION || 'us-east-1',

src/routes/files.ts

@@ -2,6 +2,7 @@ import { createReadStream } from 'node:fs';
 import { nanoid } from 'nanoid';
 import { findFileByPublicId } from '../db/files';
 import { fileInfoCache } from '../utils/cache';
+import { createChunkedObjectResponse } from '../utils/chunked-storage';
 import { cleanupTempFile, formatCreatedAt, getErrorMessage } from '../utils/file';
 import logger from '../utils/logger';
 import { metricsCollector } from '../utils/metrics';
@@ -52,6 +53,14 @@ export const handleFileRedirect = async (req: RequestWithParams): Promise<Respon
       return fail(404, 'File not found');
     }
 
+    if (file.storageBackend === 'chunked') {
+      if (file.archiveEntryName) {
+        return fail(501, 'Archive entry extraction is not supported for chunked files');
+      }
+      const range = { type: 'none' as const };
+      return createChunkedObjectResponse({ file, range, reqId: '' });
+    }
+
     const archiveEntryName = file.archiveEntryName;
     if (archiveEntryName) {
       const archiveFileId = file.archiveTelegramFileId || file.telegramFileId;

src/routes/s3.ts

@@ -18,6 +18,7 @@ import {
 } from '../db/multipart';
 import type { File } from '../db/schema';
 import { config } from '../env';
+import { createChunkedObjectResponse, storeFileInTelegramChunks } from '../utils/chunked-storage';
 import { cleanupTempFile, computeHash, ensureExtension, getErrorMessage } from '../utils/file';
 import logger from '../utils/logger';
 import { verifyPresignedUrl, verifySignature } from '../utils/s3/auth';
@@ -319,6 +320,35 @@ const handleGetObject = async (
       reqId,
     );
 
+  if (file.storageBackend === 'chunked') {
+    const totalSize = Number(file.sizeBytes);
+    const range = parseRangeHeader(headers.range || null, totalSize);
+    if (range.type === 'invalid') {
+      return s3ErrorResponse(
+        'InvalidRange',
+        'The requested range is not satisfiable.',
+        `/${bucket}/${key}`,
+        416,
+        reqId,
+        {
+          'content-range': unsatisfiedContentRange(totalSize),
+        },
+      );
+    }
+    try {
+      return await createChunkedObjectResponse({ file, range, reqId });
+    } catch (error) {
+      logger.warn('Chunked object content fetch failed', { key, error: getErrorMessage(error) });
+      return s3ErrorResponse(
+        'InternalError',
+        'Failed to fetch object content from storage',
+        `/${bucket}/${key}`,
+        502,
+        reqId,
+      );
+    }
+  }
+
   if (file.multipartUploadId) {
     return handleGetMultipartObject(file, bucket, key, headers, reqId);
   }
@@ -545,9 +575,28 @@ const storeFileToTelegram = async (
     contentType,
   );
 
+  const bucketId = bucketRecord.id;
+  const partFileNamePrefix = `s3-${bucketRecord.name}-${key.replace(/\//g, '_')}`;
+
+  if (buffer.byteLength > config.telegramChunkSizeBytes) {
+    const file = await storeFileInTelegramChunks({
+      tempPath,
+      partFileNamePrefix,
+      fileName: finalFileName,
+      mimeType,
+      sizeBytes: buffer.byteLength,
+      fileType: 'document',
+      uploaderId: 0,
+      bucketId,
+      s3Key: key,
+    });
+    await cleanupTempFile(tempPath);
+    return s3Response(null, 200, reqId, { etag: `"${file.fileHash}"` });
+  }
+
   const forwardResult = await forwardToStorage(
     createReadStream(tempPath),
-    `s3-${bucketRecord.name}-${key.replace(/\//g, '_')}`,
+    partFileNamePrefix,
     'document',
   );
 
@@ -566,7 +615,7 @@ const storeFileToTelegram = async (
     fileType: 'document',
     uploaderId: 0,
     fileHash: hash,
-    bucketId: bucketRecord.id,
+    bucketId,
     s3Key: key,
     storageBackend: 'telegram',
     isDeleted: false,
@@ -613,6 +662,17 @@ const handleCopyObject = async (
       reqId,
     );
 
+  if (sourceFile.storageBackend === 'chunked') {
+    // Copying chunked objects is not yet supported.
+    return s3ErrorResponse(
+      'NotImplemented',
+      'Copying chunked objects is not yet implemented.',
+      copySource,
+      501,
+      reqId,
+    );
+  }
+
   // Conditional copy: if-match / if-none-match checks
   const ifMatch = headers['x-amz-copy-source-if-match'];
   const ifNoneMatch = headers['x-amz-copy-source-if-none-match'];
@@ -883,6 +943,16 @@ const handleUploadPart = async (
   const body = await req.arrayBuffer();
   const buffer = Buffer.from(body);
 
+  if (buffer.byteLength > config.telegramChunkSizeBytes) {
+    return s3ErrorResponse(
+      'EntityTooLarge',
+      `Your proposed upload part size (${buffer.byteLength} bytes) exceeds the maximum allowed part size (${config.telegramChunkSizeBytes} bytes) for this storage backend. Use smaller part sizes.`,
+      `/${bucket}/${key}`,
+      400,
+      reqId,
+    );
+  }
+
   const tempPath = `/tmp/teleuploader-mp-${nanoid()}`;
   await Bun.write(tempPath, buffer);
 

src/routes/upload.ts

@@ -2,6 +2,7 @@ import { createWriteStream } from 'node:fs';
 import { nanoid } from 'nanoid';
 import { findFileByHash } from '../db/files';
 import { config } from '../env';
+import { storeFileInTelegramChunks } from '../utils/chunked-storage';
 import {
   buildUploadResponse,
   checkFileSize,
@@ -200,6 +201,20 @@ const handleMultipartUpload = async (req: Request): Promise<Response> => {
       return Response.json({ error: `File size exceeds ${fileType} limit` }, { status: 400 });
     }
 
+    if (prepared.sizeBytes > config.telegramChunkSizeBytes) {
+      const file = await storeFileInTelegramChunks({
+        tempPath: prepared.tempPath,
+        partFileNamePrefix: `direct-${prepared.fileHash?.slice(0, 16) || 'upload'}`,
+        fileName: finalFileName,
+        mimeType,
+        sizeBytes: prepared.sizeBytes,
+        fileType,
+        uploaderId: 0,
+      });
+      await cleanupTempFile(prepared.tempPath);
+      return Response.json(buildUploadResponse(file, config.baseUrl), { status: 200 });
+    }
+
     const uploaded = await enqueuePreparedUpload({
       prepared,
       fileName: finalFileName,
@@ -257,6 +272,21 @@ const handleJSONUpload = async (req: Request): Promise<Response> => {
     }
 
     const prepared = await writeBufferToTemp(fileBytes, hash);
+
+    if (prepared.sizeBytes > config.telegramChunkSizeBytes) {
+      const file = await storeFileInTelegramChunks({
+        tempPath: prepared.tempPath,
+        partFileNamePrefix: `direct-${prepared.fileHash?.slice(0, 16) || 'json'}`,
+        fileName: finalFileName,
+        mimeType,
+        sizeBytes: prepared.sizeBytes,
+        fileType,
+        uploaderId: 0,
+      });
+      await cleanupTempFile(prepared.tempPath);
+      return Response.json(buildUploadResponse(file, config.baseUrl), { status: 200 });
+    }
+
     const uploaded = await enqueuePreparedUpload({
       prepared,
       fileName: finalFileName,

src/routes/web-api.ts

@@ -8,6 +8,7 @@ import {
   softDeleteFile,
 } from '../db/files-ext';
 import { config } from '../env';
+import { createChunkedObjectResponse, storeFileInTelegramChunks } from '../utils/chunked-storage';
 import { cleanupTempFile, computeHash, ensureExtension, getErrorMessage } from '../utils/file';
 import logger from '../utils/logger';
 import { forwardToStorage, getFileInfo } from '../utils/telegram';
@@ -126,9 +127,35 @@ export const handleUploadObjectV1 = async (
     file.type || 'application/octet-stream',
   );
 
+  const partFileNamePrefix = `s3-${bucket.name}-${key.replace(/\//g, '_')}`;
+
+  if (buffer.byteLength > config.telegramChunkSizeBytes) {
+    const file = await storeFileInTelegramChunks({
+      tempPath,
+      partFileNamePrefix,
+      fileName: finalFileName,
+      mimeType,
+      sizeBytes: buffer.byteLength,
+      fileType: 'document',
+      uploaderId: 0,
+      bucketId: bucket.id,
+      s3Key: key,
+    });
+    await cleanupTempFile(tempPath);
+    return json(
+      {
+        key,
+        size: buffer.byteLength,
+        etag: hash,
+        downloadUrl: `${config.baseUrl}/f/${file.publicId}`,
+      },
+      201,
+    );
+  }
+
   const forwardResult = await forwardToStorage(
     createReadStream(tempPath),
-    `s3-${bucket.name}-${key.replace(/\//g, '_')}`,
+    partFileNamePrefix,
     'document',
   );
 
@@ -183,6 +210,11 @@ export const handleDownloadObjectV1 = async (
   const file = await findFileByBucketAndKey(bucket.id, params.key!);
   if (!file) return jsonError('Object not found', 404);
 
+  if (file.storageBackend === 'chunked') {
+    const range = { type: 'none' as const };
+    return createChunkedObjectResponse({ file, range, reqId: '' });
+  }
+
   const fileInfo = await getFileInfo(file.telegramFileId);
   const redirectUrl = `https://api.telegram.org/file/bot${fileInfo.bot_token}/${fileInfo.file_path}`;
 
@@ -209,6 +241,10 @@ export const handleCopyObjectV1 = async (req: Request, params: RouteParams): Pro
   const sourceFile = await findFileByBucketAndKey(sourceBucket.id, body.sourceKey);
   if (!sourceFile) return jsonError('Source object not found', 404);
 
+  if (sourceFile.storageBackend === 'chunked') {
+    return json({ error: 'Copying chunked objects is not implemented' }, 501);
+  }
+
   const publicId = nanoid();
   const { db, files: fileSchema } = await import('../db/index');
 

src/utils/chunked-storage.ts

@@ -0,0 +1,226 @@
+import { randomUUID } from 'node:crypto';
+import { createReadStream } from 'node:fs';
+import { gzipSync } from 'node:zlib';
+import { nanoid } from 'nanoid';
+import { db, files as fileSchema } from '../db';
+import { insertFileParts, listFileParts, type NewFilePartInput } from '../db/file-parts';
+import type { File } from '../db/schema';
+import { config } from '../env';
+import { computeHash } from './file';
+import { createGetObjectResponse, type ObjectPartSource } from './s3/object-stream';
+import type { RangeParseResult } from './s3/range';
+import { forwardToStorage, getFileInfo } from './telegram';
+
+export type ChunkCompressionAlgorithm = 'gzip' | null;
+
+export interface ChunkedUploadPart {
+  partNumber: number;
+  telegramFileId: string;
+  telegramFileUniqueId: string;
+  storageMessageId: number;
+  sizeBytes: number;
+  storedSizeBytes: number;
+  compressionAlgorithm: ChunkCompressionAlgorithm;
+  etag: string;
+}
+
+export interface ChunkedUploadResult {
+  parts: ChunkedUploadPart[];
+  fileHash: string;
+  totalSizeBytes: number;
+}
+
+export interface ChunkedFileInput {
+  tempPath: string;
+  partFileNamePrefix: string;
+  fileName: string;
+  mimeType: string;
+  sizeBytes: number;
+  fileType: string;
+  uploaderId: number;
+  bucketId?: string | null;
+  s3Key?: string | null;
+}
+
+const asSafeChunkSize = (chunkSizeBytes: number): number => {
+  if (!Number.isSafeInteger(chunkSizeBytes) || chunkSizeBytes <= 0) {
+    throw new Error('Invalid Telegram chunk size');
+  }
+  return chunkSizeBytes;
+};
+
+const maybeCompressChunk = (
+  chunk: Buffer,
+  compress: boolean,
+  compressionMinSizeBytes: number,
+): { bytes: Buffer; compressionAlgorithm: ChunkCompressionAlgorithm } => {
+  if (!compress || chunk.byteLength < compressionMinSizeBytes) {
+    return { bytes: chunk, compressionAlgorithm: null };
+  }
+
+  const gzipped = gzipSync(chunk);
+  if (gzipped.byteLength >= chunk.byteLength) {
+    return { bytes: chunk, compressionAlgorithm: null };
+  }
+
+  return { bytes: gzipped, compressionAlgorithm: 'gzip' };
+};
+
+export const uploadFileInTelegramChunks = async (input: {
+  tempPath: string;
+  partFileNamePrefix: string;
+  chunkSizeBytes: number;
+  compress: boolean;
+  compressionMinSizeBytes: number;
+}): Promise<ChunkedUploadResult> => {
+  const chunkSizeBytes = asSafeChunkSize(input.chunkSizeBytes);
+  const hasher = new Bun.CryptoHasher('sha256');
+  const parts: ChunkedUploadPart[] = [];
+  let totalSizeBytes = 0;
+  let partNumber = 0;
+
+  const stream = createReadStream(input.tempPath, { highWaterMark: chunkSizeBytes });
+
+  for await (const data of stream) {
+    const chunk = Buffer.isBuffer(data) ? data : Buffer.from(data as Uint8Array);
+    if (chunk.byteLength === 0) continue;
+
+    partNumber += 1;
+    totalSizeBytes += chunk.byteLength;
+    hasher.update(chunk);
+
+    const { bytes, compressionAlgorithm } = maybeCompressChunk(
+      chunk,
+      input.compress,
+      input.compressionMinSizeBytes,
+    );
+    const forwardResult = await forwardToStorage(
+      bytes,
+      `${input.partFileNamePrefix}.part-${partNumber}`,
+      'document',
+    );
+
+    parts.push({
+      partNumber,
+      telegramFileId: forwardResult.telegramFileId,
+      telegramFileUniqueId: forwardResult.telegramFileUniqueId,
+      storageMessageId: forwardResult.storageMessageId,
+      sizeBytes: chunk.byteLength,
+      storedSizeBytes: bytes.byteLength,
+      compressionAlgorithm,
+      etag: computeHash(chunk),
+    });
+  }
+
+  return {
+    parts,
+    fileHash: hasher.digest('hex'),
+    totalSizeBytes,
+  };
+};
+
+export const storeFileInTelegramChunks = async (input: ChunkedFileInput): Promise<File> => {
+  const upload = await uploadFileInTelegramChunks({
+    tempPath: input.tempPath,
+    partFileNamePrefix: input.partFileNamePrefix,
+    chunkSizeBytes: config.telegramChunkSizeBytes,
+    compress: config.compressChunkedUploads,
+    compressionMinSizeBytes: config.chunkCompressionMinSizeBytes,
+  });
+
+  const firstPart = upload.parts[0];
+  if (!firstPart) {
+    throw new Error('Chunked upload produced no parts');
+  }
+
+  const now = new Date();
+  const fileId = randomUUID();
+  const publicId = nanoid();
+  const file: File = {
+    id: fileId,
+    publicId,
+    telegramFileId: firstPart.telegramFileId,
+    telegramFileUniqueId: firstPart.telegramFileUniqueId,
+    storageChatId: config.storageChatId,
+    storageMessageId: firstPart.storageMessageId,
+    fileName: input.fileName,
+    mimeType: input.mimeType,
+    sizeBytes: upload.totalSizeBytes,
+    fileType: input.fileType,
+    uploaderId: input.uploaderId,
+    fileHash: upload.fileHash,
+    archiveTelegramFileId: null,
+    archiveStorageMessageId: null,
+    archiveFileName: null,
+    archiveEntryName: null,
+    archiveMimeType: null,
+    archiveSizeBytes: null,
+    bucketId: input.bucketId ?? null,
+    s3Key: input.s3Key ?? null,
+    storageBackend: 'chunked',
+    isDeleted: false,
+    multipartUploadId: null,
+    partCount: upload.parts.length,
+    createdAt: now,
+    updatedAt: now,
+  };
+
+  await db.insert(fileSchema).values(file);
+
+  const fileParts: NewFilePartInput[] = upload.parts.map((part) => ({
+    fileId,
+    partNumber: part.partNumber,
+    telegramFileId: part.telegramFileId,
+    telegramFileUniqueId: part.telegramFileUniqueId,
+    storageChatId: config.storageChatId,
+    storageMessageId: part.storageMessageId,
+    sizeBytes: part.sizeBytes,
+    storedSizeBytes: part.storedSizeBytes,
+    compressionAlgorithm: part.compressionAlgorithm,
+    etag: part.etag,
+  }));
+
+  await insertFileParts(fileParts);
+  return file;
+};
+
+export const buildChunkedObjectSources = async (file: File): Promise<ObjectPartSource[]> => {
+  const parts = await listFileParts(file.id);
+  const sources: ObjectPartSource[] = [];
+
+  for (const part of parts) {
+    const fileInfo = await getFileInfo(part.telegramFileId);
+    sources.push({
+      telegramFileId: part.telegramFileId,
+      telegramUrl: `https://api.telegram.org/file/bot${fileInfo.bot_token}/${fileInfo.file_path}`,
+      sizeBytes: part.sizeBytes,
+      storedSizeBytes: part.storedSizeBytes,
+      compressionAlgorithm: part.compressionAlgorithm,
+      partNumber: part.partNumber,
+    });
+  }
+
+  return sources;
+};
+
+export const createChunkedObjectResponse = async (input: {
+  file: File;
+  range: RangeParseResult;
+  reqId: string;
+}): Promise<Response> => {
+  const parts = await buildChunkedObjectSources(input.file);
+  if (parts.length === 0) {
+    throw new Error('Chunked object has no parts');
+  }
+
+  return createGetObjectResponse({
+    reqId: input.reqId,
+    contentType: input.file.mimeType,
+    etag: input.file.fileHash || parts.map((p) => p.telegramFileId).join('-'),
+    lastModified:
+      input.file.createdAt instanceof Date ? input.file.createdAt : new Date(input.file.createdAt),
+    totalSize: Number(input.file.sizeBytes),
+    parts,
+    range: input.range,
+  });
+};

src/utils/s3/object-stream.ts

@@ -1,3 +1,4 @@
+import { gunzipSync } from 'node:zlib';
 import { applyS3Headers } from './headers';
 import { contentRange, type RangeParseResult } from './range';
 
@@ -6,6 +7,8 @@ export interface ObjectPartSource {
   telegramUrl: string;
   sizeBytes: number;
   partNumber: number;
+  storedSizeBytes?: number;
+  compressionAlgorithm?: 'gzip' | null;
 }
 
 export interface ObjectResponseInput {
@@ -54,10 +57,26 @@ const planParts = (parts: ObjectPartSource[], start: number, end: number): Plann
   return planned;
 };
 
+const streamFromBytes = (bytes: Uint8Array): ReadableStream<Uint8Array> =>
+  new Response(bytes).body!;
+
+const fetchWholePartBytes = async (telegramUrl: string): Promise<Uint8Array> => {
+  const res = await fetch(telegramUrl);
+  if (!res.ok) throw new Error(`Telegram fetch failed: ${res.status}`);
+  return new Uint8Array(await res.arrayBuffer());
+};
+
 const fetchPartBody = async (planned: PlannedPart): Promise<ReadableStream<Uint8Array>> => {
-  const rangeHeader = `bytes=${planned.relativeStart}-${planned.relativeEnd}`;
   const wantsWholePart =
     planned.relativeStart === 0 && planned.relativeEnd === planned.part.sizeBytes - 1;
+
+  if (planned.part.compressionAlgorithm === 'gzip') {
+    const storedBytes = await fetchWholePartBytes(planned.part.telegramUrl);
+    const bytes = gunzipSync(storedBytes);
+    return streamFromBytes(bytes.subarray(planned.relativeStart, planned.relativeEnd + 1));
+  }
+
+  const rangeHeader = `bytes=${planned.relativeStart}-${planned.relativeEnd}`;
   const res = await fetch(
     planned.part.telegramUrl,
     wantsWholePart ? undefined : { headers: { range: rangeHeader } },
@@ -66,7 +85,7 @@ const fetchPartBody = async (planned: PlannedPart): Promise<ReadableStream<Uint8
   if (wantsWholePart || res.status === 206) return res.body!;
 
   const bytes = new Uint8Array(await res.arrayBuffer());
-  return new Response(bytes.slice(planned.relativeStart, planned.relativeEnd + 1)).body!;
+  return streamFromBytes(bytes.slice(planned.relativeStart, planned.relativeEnd + 1));
 };
 
 const concatPartStreams = (plannedParts: PlannedPart[]): ReadableStream<Uint8Array> =>