Phase 5 red: collection and file decryption tests

10 tests covering decryptCollection (key + name decryption from raw
server JSON, type mapping, isShared, missing name, wrong key) and
decryptFile (key + metadata decryption, fileType number-to-string
mapping, file/thumbnail header passthrough, wrong key).

Adds src/model/types.ts with both raw (server) and decrypted (library)
type definitions. src/model/decrypt.ts has throwing stubs.

src/model/decrypt.ts

@@ -0,0 +1,23 @@
+// Stub: see the README "Development workflow" section for TDD policy.
+
+import type {
+    Collection,
+    EnteFile,
+    RawCollection,
+    RawEnteFile,
+} from "./types.js";
+
+export const decryptCollection = (
+    _raw: RawCollection,
+    _masterKey: Uint8Array,
+    _currentUserID?: number,
+): Collection => {
+    throw new Error("model.decryptCollection not implemented");
+};
+
+export const decryptFile = (
+    _raw: RawEnteFile,
+    _collectionKey: Uint8Array,
+): EnteFile => {
+    throw new Error("model.decryptFile not implemented");
+};

src/model/index.ts

@@ -0,0 +1,12 @@
+export { decryptCollection, decryptFile } from "./decrypt.js";
+export type {
+    Collection,
+    CollectionType,
+    EnteFile,
+    FileBlob,
+    FileMetadata,
+    FileType,
+    Microseconds,
+    RawCollection,
+    RawEnteFile,
+} from "./types.js";

src/model/types.ts

@@ -0,0 +1,74 @@
+export type Microseconds = number;
+
+export type CollectionType =
+    | "album"
+    | "folder"
+    | "favorites"
+    | "uncategorized"
+    | "unknown";
+
+export interface Collection {
+    id: number;
+    ownerID: number;
+    key: Uint8Array;
+    name: string;
+    type: CollectionType;
+    updationTime: Microseconds;
+    isShared: boolean;
+}
+
+export type FileType = "image" | "video" | "livePhoto" | "unknown";
+
+export interface FileMetadata {
+    title: string;
+    fileType: FileType;
+    creationTime: Microseconds;
+    modificationTime: Microseconds;
+    latitude?: number;
+    longitude?: number;
+    hash?: string;
+}
+
+export interface FileBlob {
+    decryptionHeader: string;
+    size?: number;
+}
+
+export interface EnteFile {
+    id: number;
+    collectionID: number;
+    ownerID: number;
+    key: Uint8Array;
+    metadata: FileMetadata;
+    file: FileBlob;
+    thumbnail: FileBlob;
+    updationTime: Microseconds;
+}
+
+// Raw shapes as they arrive from the Ente API, before decryption.
+
+export interface RawCollection {
+    id: number;
+    owner: { id: number };
+    encryptedKey: string;
+    keyDecryptionNonce: string;
+    encryptedName?: string;
+    nameDecryptionNonce?: string;
+    type: string;
+    updationTime: number;
+    isDeleted?: boolean;
+}
+
+export interface RawEnteFile {
+    id: number;
+    collectionID: number;
+    ownerID: number;
+    encryptedKey: string;
+    keyDecryptionNonce: string;
+    metadata: { encryptedData: string; decryptionHeader: string };
+    info?: { fileSize?: number; thumbSize?: number };
+    file: { decryptionHeader: string };
+    thumbnail: { decryptionHeader: string };
+    updationTime: number;
+    isDeleted?: boolean;
+}