diff --git a/src/index.ts b/src/index.ts
index 73e5439..9e90b0f 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -36,11 +36,19 @@ export {
 export {
     Library,
     DEFAULT_REFRESH_INTERVAL_SECONDS,
+    Album,
+    Photo,
     type LibraryClient,
     type LibraryOptions,
     type LibraryStatus,
     type RefreshEvent,
     type RefreshProgressCallback,
+    type AlbumsAPI,
+    type PhotosAPI,
+    type TimelineAPI,
+    type PhotoFilter,
+    type TimelineGroup,
+    type GroupBy,
 } from "./library/index.js";
 export type {
     AlbumRecord,
diff --git a/src/library/index.ts b/src/library/index.ts
index 4d06e87..9a1b0fa 100644
--- a/src/library/index.ts
+++ b/src/library/index.ts
@@ -31,6 +31,25 @@ import {
     type LibrarySnapshot,
     type LibraryChange,
 } from "./records.js";
+import {
+    makeAlbumsAPI,
+    makePhotosAPI,
+    makeTimelineAPI,
+    type AlbumsAPI,
+    type PhotosAPI,
+    type TimelineAPI,
+} from "./read.js";
+
+export {
+    Album,
+    Photo,
+    type AlbumsAPI,
+    type PhotosAPI,
+    type TimelineAPI,
+    type PhotoFilter,
+    type TimelineGroup,
+    type GroupBy,
+} from "./read.js";
 import type { CollectionsPage, FilesPage } from "../client.js";
 import type { Collection, EnteFile } from "../model/types.js";
 
@@ -88,6 +107,13 @@ export class Library {
     readonly cacheDirectory: string;
     readonly downloadDirectory?: string;
 
+    // The in-process read surface (issue #44). Each namespace answers
+    // synchronously from the live record projection; no read touches the
+    // network.
+    readonly albums: AlbumsAPI;
+    readonly photos: PhotosAPI;
+    readonly timeline: TimelineAPI;
+
     private readonly client: LibraryClient;
     private readonly store: MetadataStore;
     private readonly userID: number;
@@ -127,6 +153,13 @@ export class Library {
         this.intervalMs = args.intervalMs;
         this.onProgress = args.onProgress;
         this.lastRecords = this.deriveNow();
+
+        // The read namespaces derive fresh from the store on each call, so they
+        // always reflect the latest refresh.
+        const derive = (): DerivedRecords => this.deriveNow();
+        this.albums = makeAlbumsAPI(derive);
+        this.photos = makePhotosAPI(derive);
+        this.timeline = makeTimelineAPI(derive);
     }
 
     // Load the cache and start the refresh loop. With an empty cache the first
diff --git a/src/library/read.ts b/src/library/read.ts
new file mode 100644
index 0000000..3af8069
--- /dev/null
+++ b/src/library/read.ts
@@ -0,0 +1,319 @@
+// The in-process read surface over the local cache (issue #44).
+//
+// A CLI or an in-process script reads albums, photos, and a grouped timeline
+// through `lib.albums`, `lib.photos`, and `lib.timeline`. Every call is
+// answered synchronously from the same plain-record projection the GUI reads
+// (`deriveRecords`, issue #43); nothing here touches the network. Every method
+// takes a single named-argument object.
+//
+// The `Album` and `Photo` classes are thin, in-process-only wrappers over
+// those records: a caller that holds an object reference gets typed field
+// access and, for an album, its photos. They are not sent across IPC — the
+// plain records are the serializable surface, and `record()` returns one.
+// Content-fetch methods (`Photo.original` / `thumbnail`) belong to a later
+// unit; this surface is read-only.
+
+import type { CollectionType, FileType } from "../model/types.js";
+import type { AlbumRecord, PhotoRecord, DerivedRecords } from "./records.js";
+
+// Newest first, with fileID as a stable tiebreak so equal-timed files order
+// deterministically — the same order the record projection uses.
+const byNewest = (a: PhotoRecord, b: PhotoRecord): number =>
+    b.takenAt - a.takenAt || b.fileID - a.fileID;
+
+// Albums newest updated first, collection id breaking ties. This is the order
+// `albums.list` returns and the order `byName` resolves a name collision in.
+const byNewestAlbum = (a: AlbumRecord, b: AlbumRecord): number =>
+    b.updationTime - a.updationTime || b.collectionID - a.collectionID;
+
+// A single photo. Field access mirrors `PhotoRecord`; `record()` returns the
+// underlying plain record for callers that need the IPC-safe value.
+export class Photo {
+    constructor(private readonly rec: PhotoRecord) {}
+
+    get fileID(): number {
+        return this.rec.fileID;
+    }
+    get albumIDs(): number[] {
+        return this.rec.albumIDs;
+    }
+    get title(): string {
+        return this.rec.title;
+    }
+    get takenAt(): number {
+        return this.rec.takenAt;
+    }
+    get fileType(): FileType {
+        return this.rec.fileType;
+    }
+    get caption(): string | undefined {
+        return this.rec.caption;
+    }
+    get width(): number | undefined {
+        return this.rec.width;
+    }
+    get height(): number | undefined {
+        return this.rec.height;
+    }
+    get latitude(): number | undefined {
+        return this.rec.latitude;
+    }
+    get longitude(): number | undefined {
+        return this.rec.longitude;
+    }
+    get isArchived(): boolean {
+        return this.rec.isArchived;
+    }
+    get isHidden(): boolean {
+        return this.rec.isHidden;
+    }
+
+    record(): PhotoRecord {
+        return this.rec;
+    }
+}
+
+// A single album. `photos.list()` returns the album's photos as wrappers,
+// newest first (the record already stores `fileIDs` in that order).
+export class Album {
+    constructor(
+        private readonly rec: AlbumRecord,
+        private readonly records: DerivedRecords,
+    ) {}
+
+    get collectionID(): number {
+        return this.rec.collectionID;
+    }
+    get name(): string {
+        return this.rec.name;
+    }
+    get type(): CollectionType {
+        return this.rec.type;
+    }
+    get isShared(): boolean {
+        return this.rec.isShared;
+    }
+    get updationTime(): number {
+        return this.rec.updationTime;
+    }
+    get fileIDs(): number[] {
+        return this.rec.fileIDs;
+    }
+
+    get photos(): { list: () => Photo[] } {
+        return { list: (): Photo[] => this.listPhotos() };
+    }
+
+    record(): AlbumRecord {
+        return this.rec;
+    }
+
+    private listPhotos(): Photo[] {
+        const out: Photo[] = [];
+        for (const id of this.rec.fileIDs) {
+            const p = this.records.photos.get(id);
+            if (p) out.push(new Photo(p));
+        }
+        return out;
+    }
+}
+
+export interface AlbumsAPI {
+    list(): Album[];
+    byName(args: { albumName: string }): Album | undefined;
+    byID(args: { collectionID: number }): Album | undefined;
+}
+
+export interface PhotosAPI {
+    byID(args: { fileID: number }): Photo | undefined;
+    // Plain records for the requested ids, in the order requested, each id at
+    // most once, unknown ids dropped.
+    records(args: { fileIDs: number[] }): PhotoRecord[];
+}
+
+export type GroupBy = "day" | "week" | "month";
+
+// A filter over the timeline. All fields are optional and combine with AND.
+// Hidden photos are never included, regardless of this filter.
+export interface PhotoFilter {
+    // Keep only photos that belong to this album.
+    albumID?: number;
+    // Case-insensitive substring of the title, caption, or any album name the
+    // photo belongs to.
+    text?: string;
+    // Keep only photos of one of these types.
+    fileTypes?: FileType[];
+    // `true` keeps only geotagged photos; `false` keeps only those without a
+    // location; omitted places no constraint.
+    hasLocation?: boolean;
+    // Archived photos are excluded unless this is `true`. Defaults to `false`.
+    includeArchived?: boolean;
+}
+
+export interface TimelineGroup {
+    // The period's identity: `YYYY-MM-DD` for day and week (the Monday), and
+    // `YYYY-MM` for month.
+    key: string;
+    // Local-time milliseconds at the start of the period.
+    startsAt: number;
+    // The period's files, newest first, each file once.
+    fileIDs: number[];
+}
+
+export interface TimelineAPI {
+    groups(args: { groupBy: GroupBy; filter?: PhotoFilter }): TimelineGroup[];
+}
+
+export const makeAlbumsAPI = (derive: () => DerivedRecords): AlbumsAPI => ({
+    list: (): Album[] => {
+        const records = derive();
+        return [...records.albums.values()]
+            .sort(byNewestAlbum)
+            .map((rec) => new Album(rec, records));
+    },
+    byID: ({ collectionID }): Album | undefined => {
+        const records = derive();
+        const rec = records.albums.get(collectionID);
+        return rec ? new Album(rec, records) : undefined;
+    },
+    byName: ({ albumName }): Album | undefined => {
+        const records = derive();
+        // Names are not unique in Ente; resolve a collision deterministically
+        // to the newest-updated album, matching `list` order.
+        const match = [...records.albums.values()]
+            .sort(byNewestAlbum)
+            .find((rec) => rec.name === albumName);
+        return match ? new Album(match, records) : undefined;
+    },
+});
+
+export const makePhotosAPI = (derive: () => DerivedRecords): PhotosAPI => ({
+    byID: ({ fileID }): Photo | undefined => {
+        const rec = derive().photos.get(fileID);
+        return rec ? new Photo(rec) : undefined;
+    },
+    records: ({ fileIDs }): PhotoRecord[] => {
+        const { photos } = derive();
+        const seen = new Set<number>();
+        const out: PhotoRecord[] = [];
+        for (const id of fileIDs) {
+            if (seen.has(id)) continue;
+            const rec = photos.get(id);
+            if (rec) {
+                out.push(rec);
+                seen.add(id);
+            }
+        }
+        return out;
+    },
+});
+
+export const makeTimelineAPI = (derive: () => DerivedRecords): TimelineAPI => ({
+    groups: ({ groupBy, filter }): TimelineGroup[] => {
+        const records = derive();
+        return groupPhotos(filterPhotos(records, filter), groupBy);
+    },
+});
+
+// Apply a `PhotoFilter` to the projection. Hidden photos are always dropped;
+// archived photos are dropped unless `includeArchived` asks for them.
+const filterPhotos = (
+    records: DerivedRecords,
+    filter?: PhotoFilter,
+): PhotoRecord[] => {
+    const f = filter ?? {};
+    const includeArchived = f.includeArchived ?? false;
+    const needle = f.text?.toLowerCase();
+    const out: PhotoRecord[] = [];
+    for (const rec of records.photos.values()) {
+        if (rec.isHidden) continue;
+        if (rec.isArchived && !includeArchived) continue;
+        if (f.albumID !== undefined && !rec.albumIDs.includes(f.albumID))
+            continue;
+        if (f.fileTypes !== undefined && !f.fileTypes.includes(rec.fileType))
+            continue;
+        if (f.hasLocation !== undefined) {
+            const has =
+                rec.latitude !== undefined && rec.longitude !== undefined;
+            if (has !== f.hasLocation) continue;
+        }
+        if (needle !== undefined && !matchesText(rec, needle, records))
+            continue;
+        out.push(rec);
+    }
+    return out;
+};
+
+const matchesText = (
+    rec: PhotoRecord,
+    needle: string,
+    records: DerivedRecords,
+): boolean => {
+    if (rec.title.toLowerCase().includes(needle)) return true;
+    if (rec.caption !== undefined && rec.caption.toLowerCase().includes(needle))
+        return true;
+    for (const id of rec.albumIDs) {
+        const album = records.albums.get(id);
+        if (album && album.name.toLowerCase().includes(needle)) return true;
+    }
+    return false;
+};
+
+// Bucket photos into periods, groups newest first, members newest first.
+const groupPhotos = (
+    photos: PhotoRecord[],
+    groupBy: GroupBy,
+): TimelineGroup[] => {
+    const buckets = new Map<
+        string,
+        { startsAt: number; recs: PhotoRecord[] }
+    >();
+    for (const rec of photos) {
+        const { key, startsAt } = periodOf(rec.takenAt, groupBy);
+        const bucket = buckets.get(key);
+        if (bucket) bucket.recs.push(rec);
+        else buckets.set(key, { startsAt, recs: [rec] });
+    }
+    const groups: TimelineGroup[] = [];
+    for (const [key, bucket] of buckets) {
+        bucket.recs.sort(byNewest);
+        groups.push({
+            key,
+            startsAt: bucket.startsAt,
+            fileIDs: bucket.recs.map((r) => r.fileID),
+        });
+    }
+    groups.sort((a, b) => b.startsAt - a.startsAt);
+    return groups;
+};
+
+const pad = (n: number): string => String(n).padStart(2, "0");
+
+const dateKey = (d: Date): string =>
+    `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())}`;
+
+// The period a millisecond instant falls in, in local time. Weeks start on
+// Monday. `Date` normalizes out-of-range day arguments, so the week's Monday
+// is correct across month and year boundaries.
+const periodOf = (
+    takenAt: number,
+    groupBy: GroupBy,
+): { key: string; startsAt: number } => {
+    const d = new Date(takenAt);
+    const year = d.getFullYear();
+    const month = d.getMonth();
+    const day = d.getDate();
+
+    if (groupBy === "month") {
+        const start = new Date(year, month, 1);
+        return { key: `${year}-${pad(month + 1)}`, startsAt: start.getTime() };
+    }
+    if (groupBy === "week") {
+        // getDay(): 0=Sunday..6=Saturday; shift so Monday is the week start.
+        const fromMonday = (d.getDay() + 6) % 7;
+        const start = new Date(year, month, day - fromMonday);
+        return { key: dateKey(start), startsAt: start.getTime() };
+    }
+    const start = new Date(year, month, day);
+    return { key: dateKey(start), startsAt: start.getTime() };
+};