diff --git a/src/domain/ports/bucket-repository.ts b/src/domain/ports/bucket-repository.ts
new file mode 100644
index 0000000..6009d13
--- /dev/null
+++ b/src/domain/ports/bucket-repository.ts
@@ -0,0 +1,42 @@
+import type { Bucket } from '../entities/bucket';
+
+/**
+ * Repository interface for Bucket entity persistence.
+ *
+ * Abstracts the bucket CRUD operations currently in `src/db/buckets.ts`.
+ */
+export interface IBucketRepository {
+  /**
+   * Create a new bucket with the given name.
+   * @param name - The unique bucket name (S3 naming convention).
+   * @returns The newly created bucket record.
+   */
+  create(name: string): Promise<Bucket>;
+
+  /**
+   * Find a bucket by its unique name.
+   * @param name - The bucket name to look up.
+   * @returns The matching bucket, or `null` when not found.
+   */
+  findByName(name: string): Promise<Bucket | null>;
+
+  /**
+   * List all buckets, ordered alphabetically by name.
+   * @returns An array of all bucket records.
+   */
+  list(): Promise<Bucket[]>;
+
+  /**
+   * Delete a bucket and cascade-delete all associated files and multipart data.
+   * @param name - The name of the bucket to delete.
+   * @returns `true` if the bucket was deleted, `false` if it did not exist.
+   */
+  delete(name: string): Promise<boolean>;
+
+  /**
+   * Check whether a bucket with the given name exists.
+   * @param name - The bucket name to check.
+   * @returns `true` if the bucket exists, `false` otherwise.
+   */
+  exists(name: string): Promise<boolean>;
+}
diff --git a/src/domain/ports/file-part-repository.ts b/src/domain/ports/file-part-repository.ts
new file mode 100644
index 0000000..16c9432
--- /dev/null
+++ b/src/domain/ports/file-part-repository.ts
@@ -0,0 +1,30 @@
+import type { FilePart, NewFilePart } from '../entities/file-part';
+
+/**
+ * Repository interface for FilePart entity persistence.
+ *
+ * Abstracts the file-part operations currently in `src/db/file-parts.ts`.
+ * File parts represent the chunks of a large file stored across multiple
+ * Telegram messages for Telegram-safe storage.
+ */
+export interface IFilePartRepository {
+  /**
+   * Insert multiple file parts in a single operation.
+   * @param parts - An array of new file part records (auto-generated fields omitted).
+   */
+  insert(parts: NewFilePart[]): Promise<void>;
+
+  /**
+   * List all file parts for a given file, ordered by part number.
+   * @param fileId - The UUID of the parent file record.
+   * @returns An array of file parts.
+   */
+  listByFileId(fileId: string): Promise<FilePart[]>;
+
+  /**
+   * Count the number of file parts associated with a file.
+   * @param fileId - The UUID of the parent file record.
+   * @returns The part count.
+   */
+  countByFileId(fileId: string): Promise<number>;
+}
diff --git a/src/domain/ports/file-repository.ts b/src/domain/ports/file-repository.ts
new file mode 100644
index 0000000..5b648af
--- /dev/null
+++ b/src/domain/ports/file-repository.ts
@@ -0,0 +1,108 @@
+import type { File, NewFile } from '../entities/file';
+
+/**
+ * An S3-synced file record: a File entity guaranteed to have non-null
+ * bucketId and s3Key values.
+ */
+export interface S3FileRecord extends File {
+  /** S3 bucket UUID (non-null refinement) */
+  bucketId: string;
+  /** S3 object key (non-null refinement) */
+  s3Key: string;
+}
+
+/**
+ * Repository interface for File entity persistence.
+ *
+ * Abstracts all file CRUD operations currently spread across
+ * `src/db/files.ts` and `src/db/files-ext.ts`.
+ */
+export interface IFileRepository {
+  /**
+   * Find a single file by its SHA-256 content hash.
+   * @param hash - The SHA-256 hash to search for.
+   * @returns The matching file, or `null` when not found.
+   */
+  findByHash(hash: string): Promise<File | null>;
+
+  /**
+   * Find a single file by its public-facing short identifier.
+   * @param publicId - The public ID to look up.
+   * @returns The matching file, or `null` when not found.
+   */
+  findByPublicId(publicId: string): Promise<File | null>;
+
+  /**
+   * Find a single file by its Telegram file unique ID (stable across bot tokens).
+   * @param telegramFileUniqueId - The Telegram unique file ID.
+   * @returns The matching file, or `null` when not found.
+   */
+  findByUniqueId(telegramFileUniqueId: string): Promise<File | null>;
+
+  /**
+   * Find a single file by its S3 bucket and object key.
+   * @param bucketId - The bucket UUID.
+   * @param s3Key - The S3 object key.
+   * @returns The matching file, or `null` when not found.
+   */
+  findByBucketAndKey(bucketId: string, s3Key: string): Promise<File | null>;
+
+  /**
+   * Create a new file record.
+   * @param file - The file data (auto-generated fields omitted).
+   * @returns The newly created file record with all fields populated.
+   */
+  create(file: NewFile): Promise<File>;
+
+  /**
+   * List objects within a bucket, optionally filtered by prefix and delimiter.
+   *
+   * When `delimiter` is `"/"`, common prefixes (pseudo-directories) are
+   * returned separately and objects whose key continues past the delimiter
+   * are omitted from the `objects` array.
+   *
+   * @param bucketId - The bucket UUID to list from.
+   * @param prefix - Key prefix to filter by.
+   * @param delimiter - Delimiter character (e.g. `"/"`) or `null` for flat listing.
+   * @param maxKeys - Maximum number of object records to return.
+   * @param startAfter - Return only keys strictly greater than this value, or `null`.
+   * @returns A list of matching S3 file records and discovered common prefixes.
+   */
+  listByPrefix(
+    bucketId: string,
+    prefix: string,
+    delimiter: string | null,
+    maxKeys: number,
+    startAfter: string | null,
+  ): Promise<{ objects: S3FileRecord[]; prefixes: string[] }>;
+
+  /**
+   * Soft-delete a single file by bucket and key.
+   * @param bucketId - The bucket UUID.
+   * @param s3Key - The S3 object key.
+   * @returns `true` if a row was soft-deleted, `false` otherwise.
+   */
+  softDelete(bucketId: string, s3Key: string): Promise<boolean>;
+
+  /**
+   * Soft-delete multiple files within a bucket in batch.
+   * @param bucketId - The bucket UUID.
+   * @param keys - Array of S3 object keys to delete.
+   * @returns The number of rows actually soft-deleted.
+   */
+  softDeleteBatch(bucketId: string, keys: string[]): Promise<number>;
+
+  /**
+   * Count non-deleted objects in a bucket.
+   * @param bucketId - The bucket UUID.
+   * @returns The object count.
+   */
+  countByBucket(bucketId: string): Promise<number>;
+
+  /**
+   * Find soft-deleted (orphaned) file records in a bucket.
+   * @param bucketId - The bucket UUID.
+   * @returns An array of orphaned file records.
+   */
+  findOrphansByBucket(bucketId: string): Promise<File[]>;
+}
diff --git a/src/domain/ports/multipart-repository.ts b/src/domain/ports/multipart-repository.ts
new file mode 100644
index 0000000..ce35d4b
--- /dev/null
+++ b/src/domain/ports/multipart-repository.ts
@@ -0,0 +1,70 @@
+import type { MultipartUpload, MultipartPart } from '../entities/multipart';
+
+/**
+ * Repository interface for S3 multipart upload persistence.
+ *
+ * Abstracts the multipart upload operations currently in `src/db/multipart.ts`.
+ * Manages both multipart upload sessions and their individual parts.
+ */
+export interface IMultipartRepository {
+  /**
+   * Initiate a new multipart upload session.
+   * @param bucketId - The UUID of the target bucket.
+   * @param s3Key - The S3 object key being uploaded.
+   * @param initiatedBy - Identifier of the entity that initiated the upload.
+   * @returns The newly generated upload ID (nanoid).
+   */
+  create(bucketId: string, s3Key: string, initiatedBy: string): Promise<string>;
+
+  /**
+   * Find an in-progress multipart upload by its upload ID.
+   * @param uploadId - The upload identifier.
+   * @returns The matching upload, or `null` if not found or not in progress.
+   */
+  findById(uploadId: string): Promise<MultipartUpload | null>;
+
+  /**
+   * Mark a multipart upload as completed.
+   * @param uploadId - The upload identifier to complete.
+   */
+  complete(uploadId: string): Promise<void>;
+
+  /**
+   * Mark a multipart upload as aborted.
+   * @param uploadId - The upload identifier to abort.
+   */
+  abort(uploadId: string): Promise<void>;
+
+  /**
+   * Insert a single part record for a multipart upload.
+   * @param part - The part data (auto-generated fields omitted).
+   */
+  insertPart(part: Omit<MultipartPart, 'id' | 'createdAt'>): Promise<void>;
+
+  /**
+   * List all parts for a multipart upload, ordered by part number.
+   * @param uploadId - The upload identifier.
+   * @returns An array of multipart parts.
+   */
+  listParts(uploadId: string): Promise<MultipartPart[]>;
+
+  /**
+   * List in-progress multipart uploads within a bucket, with pagination.
+   *
+   * Results are ordered by S3 key and initiation timestamp.
+   *
+   * @param bucketId - The UUID of the bucket.
+   * @param maxUploads - Maximum number of uploads to return (clamped 1-1000).
+   * @param keyMarker - Return only uploads whose S3 key is strictly greater than this, or `null`.
+   * @returns A list of uploads and pagination metadata.
+   */
+  listByBucket(
+    bucketId: string,
+    maxUploads: number,
+    keyMarker: string | null,
+  ): Promise<{
+    uploads: MultipartUpload[];
+    isTruncated: boolean;
+    nextKeyMarker: string | null;
+  }>;
+}
diff --git a/src/domain/ports/telegram-service.ts b/src/domain/ports/telegram-service.ts
new file mode 100644
index 0000000..4bf9188
--- /dev/null
+++ b/src/domain/ports/telegram-service.ts
@@ -0,0 +1,68 @@
+/**
+ * Result of forwarding a file to Telegram storage.
+ */
+export interface ForwardResult {
+  /** The Telegram file_id for retrieving the file */
+  telegramFileId: string;
+  /** The Telegram unique file_id (stable across bot tokens) */
+  telegramFileUniqueId: string;
+  /** The message ID within the storage chat */
+  storageMessageId: number;
+}
+
+/**
+ * File information returned by Telegram's getFile API.
+ */
+export interface TelegramFileInfo {
+  /** File size in bytes */
+  file_size: number;
+  /** MIME type of the file */
+  mime_type: string;
+  /** Path on Telegram's file server for downloading */
+  file_path: string;
+  /** Bot token that owns the retrieved file */
+  bot_token: string;
+}
+
+/**
+ * Abstraction over Telegram bot API operations.
+ *
+ * Defines the contract for forwarding files to Telegram storage,
+ * retrieving file metadata, and managing concurrent uploads.
+ */
+export interface ITelegramService {
+  /**
+   * Forward a file chunk to the configured Telegram storage chat.
+   *
+   * @param fileChunk - The file data (ReadStream, Buffer, or file path).
+   * @param fileName - The original file name.
+   * @param fileType - The file type classification (e.g. "photo", "document").
+   * @returns The Telegram identifiers of the stored file.
+   */
+  forwardToStorage(
+    fileChunk: unknown,
+    fileName: string,
+    fileType: string,
+  ): Promise<ForwardResult>;
+
+  /**
+   * Retrieve file metadata from Telegram by file ID.
+   *
+   * Tries all configured bots; returns info from the first that owns the file.
+   *
+   * @param telegramFileId - The Telegram file_id to look up.
+   * @returns Metadata including size, MIME type, download path, and bot token.
+   */
+  getFileInfo(telegramFileId: string): Promise<TelegramFileInfo>;
+
+  /**
+   * Enqueue a task for sequential upload execution.
+   *
+   * Ensures only one Telegram upload runs at a time to avoid
+   * rate limits and resource contention.
+   *
+   * @param task - An async function performing the upload.
+   * @returns The result of the task.
+   */
+  enqueueUpload<T>(task: () => Promise<T>): Promise<T>;
+}