diff --git a/server/controllers/LibraryController.js b/server/controllers/LibraryController.js
index 73b3d5c60..a8ddbf725 100644
--- a/server/controllers/LibraryController.js
+++ b/server/controllers/LibraryController.js
@@ -830,7 +830,7 @@ class LibraryController {
     }
 
     // TODO: Create paginated queries
-    let collections = await Database.collectionModel.getOldCollectionsJsonExpanded(req.user, req.library.id, include)
+    let collections = await Database.collectionModel.getOldCollectionsJsonExpanded(req.user, req.library.id, include, payload.minified)
 
     payload.total = collections.length
 
diff --git a/server/models/Collection.js b/server/models/Collection.js
index d5f36ba9c..7789170dd 100644
--- a/server/models/Collection.js
+++ b/server/models/Collection.js
@@ -29,9 +29,10 @@ class Collection extends Model {
    * @param {import('./User')} user
    * @param {string} [libraryId]
    * @param {string[]} [include]
+   * @param {boolean} [minified=false]
    * @async
    */
-  static async getOldCollectionsJsonExpanded(user, libraryId, include) {
+  static async getOldCollectionsJsonExpanded(user, libraryId, include, minified = false) {
     let collectionWhere = null
     if (libraryId) {
       collectionWhere = {
@@ -98,7 +99,7 @@ class Collection extends Model {
 
         this.books = books
 
-        const collectionExpanded = c.toOldJSONExpanded()
+        const collectionExpanded = c.toOldJSONExpanded(minified)
 
         // Map feed if found
         if (c.feeds?.length) {
@@ -272,7 +273,11 @@ class Collection extends Model {
     }
   }
 
-  toOldJSONExpanded() {
+  /**
+   * @param {boolean} [minified=false] When true, books use the minified library item serialization
+   *                                    (omits libraryFiles and heavy media fields like chapters/tracks/audioFiles)
+   */
+  toOldJSONExpanded(minified = false) {
     if (!this.books) {
       throw new Error('Books are required to expand Collection')
     }
@@ -282,7 +287,7 @@ class Collection extends Model {
       const libraryItem = book.libraryItem
       delete book.libraryItem
       libraryItem.media = book
-      return libraryItem.toOldJSONExpanded()
+      return minified ? libraryItem.toOldJSONMinified() : libraryItem.toOldJSONExpanded()
     })
 
     return json
diff --git a/test/server/models/Collection.test.js b/test/server/models/Collection.test.js
new file mode 100644
index 000000000..962106acd
--- /dev/null
+++ b/test/server/models/Collection.test.js
@@ -0,0 +1,107 @@
+const { expect } = require('chai')
+const { Sequelize } = require('sequelize')
+
+const Database = require('../../../server/Database')
+
+describe('Collection', () => {
+  /** @type {string} */
+  let libraryId
+  /** @type {string} */
+  let collectionId
+
+  beforeEach(async () => {
+    global.ServerSettings = {}
+    Database.sequelize = new Sequelize({ dialect: 'sqlite', storage: ':memory:', logging: false })
+    Database.sequelize.uppercaseFirst = (str) => (str ? `${str[0].toUpperCase()}${str.substr(1)}` : '')
+    await Database.buildModels()
+
+    const library = await Database.libraryModel.create({ name: 'Test Library', mediaType: 'book' })
+    libraryId = library.id
+    const libraryFolder = await Database.libraryFolderModel.create({ path: '/test', libraryId: library.id })
+
+    // Build a book with heavy media: many audio files + chapters
+    const audioFiles = []
+    const chapters = []
+    for (let i = 0; i < 30; i++) {
+      audioFiles.push({
+        index: i + 1,
+        ino: `ino-${i}`,
+        duration: 600,
+        exclude: false,
+        mimeType: 'audio/mpeg',
+        metadata: { filename: `track-${i}.mp3`, ext: '.mp3', path: `/test/book/track-${i}.mp3`, relPath: `track-${i}.mp3`, size: 12345678 }
+      })
+      chapters.push({ id: i, start: i * 600, end: (i + 1) * 600, title: `Chapter ${i + 1}` })
+    }
+
+    const book = await Database.bookModel.create({ title: 'Heavy Book', audioFiles, tags: [], narrators: [], genres: [], chapters })
+
+    // libraryItem carries a large libraryFiles array (dropped by the minified form)
+    const libraryFiles = []
+    for (let i = 0; i < 30; i++) {
+      libraryFiles.push({
+        ino: `lf-${i}`,
+        metadata: { filename: `track-${i}.mp3`, ext: '.mp3', path: `/test/book/track-${i}.mp3`, relPath: `track-${i}.mp3`, size: 12345678, mtimeMs: 0, ctimeMs: 0, birthtimeMs: 0 }
+      })
+    }
+    await Database.libraryItemModel.create({ libraryFiles, mediaId: book.id, mediaType: 'book', libraryId: library.id, libraryFolderId: libraryFolder.id })
+
+    const collection = await Database.collectionModel.create({ name: 'Test Collection', libraryId: library.id })
+    collectionId = collection.id
+    await Database.collectionBookModel.create({ collectionId: collection.id, bookId: book.id, order: 1 })
+  })
+
+  afterEach(async () => {
+    await Database.sequelize.close()
+  })
+
+  describe('getOldCollectionsJsonExpanded', () => {
+    it('returns fully expanded book objects when minified is not requested', async () => {
+      const collections = await Database.collectionModel.getOldCollectionsJsonExpanded(null, libraryId, [], false)
+      expect(collections).to.have.lengthOf(1)
+      const book = collections[0].books[0]
+
+      // Library item keeps the full libraryFiles array
+      expect(book).to.have.property('libraryFiles')
+      expect(book.libraryFiles).to.be.an('array').with.lengthOf(30)
+
+      // Media keeps the heavy arrays
+      expect(book.media).to.have.property('audioFiles').that.is.an('array').with.lengthOf(30)
+      expect(book.media).to.have.property('chapters').that.is.an('array').with.lengthOf(30)
+      expect(book.media).to.have.property('tracks').that.is.an('array').with.lengthOf(30)
+    })
+
+    it('returns minified book objects that omit libraryFiles and heavy media when minified is requested', async () => {
+      const collections = await Database.collectionModel.getOldCollectionsJsonExpanded(null, libraryId, [], true)
+      expect(collections).to.have.lengthOf(1)
+      const book = collections[0].books[0]
+
+      // Library item drops libraryFiles in favor of a numFiles count
+      expect(book).to.not.have.property('libraryFiles')
+      expect(book).to.have.property('numFiles', 30)
+
+      // Media drops the heavy arrays in favor of counts
+      expect(book.media).to.not.have.property('audioFiles')
+      expect(book.media).to.not.have.property('chapters')
+      expect(book.media).to.not.have.property('tracks')
+      expect(book.media).to.have.property('numAudioFiles', 30)
+      expect(book.media).to.have.property('numChapters', 30)
+      expect(book.media).to.have.property('numTracks', 30)
+
+      // Essential display fields survive minification
+      expect(book.media).to.have.property('coverPath')
+      expect(book.media).to.have.property('duration')
+      expect(book.media.metadata).to.have.property('title', 'Heavy Book')
+    })
+
+    it('produces a materially smaller payload when minified', async () => {
+      const expanded = await Database.collectionModel.getOldCollectionsJsonExpanded(null, libraryId, [], false)
+      const minified = await Database.collectionModel.getOldCollectionsJsonExpanded(null, libraryId, [], true)
+
+      const expandedSize = JSON.stringify(expanded).length
+      const minifiedSize = JSON.stringify(minified).length
+
+      expect(minifiedSize).to.be.lessThan(expandedSize * 0.5)
+    })
+  })
+})