fix(annotations): preserve source highlight timestamps

Use KOReader highlight times for annotation history while retaining ingestion times for diagnostics. Export all stored location representations and backfill existing rows during sync. Fixes #1300
2026-11-03 08:21:39 -06:00 · 2026-09-08 16:52:36 +00:00
parent cf40058cb6
commit b9609b198e
38 changed files with 18700 additions and 42 deletions
@@ -137,7 +137,7 @@ const metadataItems = computed(() => {
  if (props.annotation.chapterTitle) items.push(props.annotation.chapterTitle)
  if (props.annotation.pageno != null) items.push(t('annotations.listItem.pageNumber', { page: props.annotation.pageno }))
  if (props.annotation.chapterIndex != null) items.push(t('annotations.listItem.chapterNumber', { chapter: props.annotation.chapterIndex + 1 }))
-  const date = formatDate(props.annotation.createdAt)
+  const date = formatDate(props.annotation.highlightedAt)
  if (date) items.push(date)
  return items
 })
@@ -31,6 +31,7 @@ function makeAnnotation(overrides: Partial<AnnotationItem> = {}): AnnotationItem
    origin: 'web',
    positionStatus: 'exact',
    chapterIndex: 0,
+    highlightedAt: '2026-01-01T00:00:00.000Z',
    createdAt: '2026-01-01T00:00:00.000Z',
    ...overrides,
  }
@@ -64,7 +64,7 @@ const { t } = useI18n()

 const STYLE_ICONS = { highlight: Highlighter, underline: Underline, strikethrough: Strikethrough, squiggly: Waves, invert: Contrast }

-const created = computed(() => new Date(props.annotation.createdAt))
+const created = computed(() => new Date(props.annotation.highlightedAt))
 const dayLabel = computed(() => formatDate(created.value, { day: 'numeric', month: 'short' }))
 const yearLabel = computed(() => formatDate(created.value, { year: 'numeric' }))
 const hub = computed(() => ('bookTitle' in props.annotation ? props.annotation : null))
@@ -86,7 +86,7 @@ function isFirstOfDay(groupIndex: number, itemIndex: number): boolean {
  if (!group) return true
  const previous = group.items[itemIndex - 1]
  if (!previous) return true
-  return dayKey(previous.createdAt) !== dayKey(group.items[itemIndex]!.createdAt)
+  return dayKey(previous.highlightedAt) !== dayKey(group.items[itemIndex]!.highlightedAt)
 }

 function isFirstOfChapter(groupIndex: number, itemIndex: number): boolean {
@@ -18,6 +18,7 @@ function annotation(overrides: Partial<AnnotationHubItem> = {}): AnnotationHubIt
    origin: 'web',
    positionStatus: 'exact',
    chapterIndex: 0,
+    highlightedAt: '2026-07-12T00:00:00.000Z',
    createdAt: '2026-07-12T00:00:00.000Z',
    bookTitle: 'A Book',
    author: 'An Author',
@@ -17,6 +17,7 @@ function item(overrides: Partial<AnnotationHubItem> = {}): AnnotationHubItem {
    origin: 'web',
    positionStatus: 'exact',
    chapterIndex: null,
+    highlightedAt: '2026-08-24T10:00:00.000Z',
    createdAt: '2026-08-24T10:00:00.000Z',
    bookTitle: 'Tartufo',
    author: 'Kira Jane Buxton',
@@ -46,11 +47,11 @@ describe('HUB_VIEWS', () => {

 describe('hubGroupKey', () => {
  it('keys each mode off the field the server sorted by', () => {
-    const row = item({ bookId: 42, color: '#38BDF8', origin: 'kobo', createdAt: '2026-03-04T00:00:00.000Z' })
+    const row = item({ bookId: 42, color: '#38BDF8', origin: 'kobo', highlightedAt: '2026-03-04T00:00:00.000Z' })
    expect(hubGroupKey(row, 'book')).toBe('42')
    expect(hubGroupKey(row, 'color')).toBe('#38BDF8')
    expect(hubGroupKey(row, 'source')).toBe('kobo')
-    expect(hubGroupKey(row, 'month')).toBe(monthKey(row.createdAt))
+    expect(hubGroupKey(row, 'month')).toBe(monthKey(row.highlightedAt))
  })
 })

@@ -58,7 +58,7 @@ export function hubGroupKey(item: AnnotationHubItem, mode: AnnotationHubGroupMod
    case 'source':
      return item.origin
    default:
-      return monthKey(item.createdAt)
+      return monthKey(item.highlightedAt)
  }
 }

@@ -89,7 +89,7 @@ const groups = computed<StreamGroup[]>(() =>
    }
    return {
      key: group.key,
-      label: formatDate(new Date(lead.createdAt), { month: 'long', year: 'numeric' }),
+      label: formatDate(new Date(lead.highlightedAt), { month: 'long', year: 'numeric' }),
      count: group.items.length,
      items: group.items,
    }
@@ -91,6 +91,7 @@ function exportJson() {
      color: h.color,
      style: h.style,
      chapter: h.chapterTitle,
+      highlightedAt: h.highlightedAt,
      createdAt: h.createdAt,
    })),
  }
@@ -73,7 +73,7 @@ const groups = computed<StreamGroup[]>(() =>
      const first = group.items[0]
      return {
        key: group.key,
-        label: first ? formatDate(new Date(first.createdAt), { day: 'numeric', month: 'long', year: 'numeric' }) : group.key,
+        label: first ? formatDate(new Date(first.highlightedAt), { day: 'numeric', month: 'long', year: 'numeric' }) : group.key,
        count: group.total,
        items: group.items,
      }
@@ -18,6 +18,7 @@ function makeHighlight(overrides: Partial<AnnotationItem> = {}): AnnotationItem
    origin: 'web',
    positionStatus: 'exact',
    chapterIndex: null,
+    highlightedAt: '2026-01-01T00:00:00.000Z',
    createdAt: '2026-01-01T00:00:00.000Z',
    ...overrides,
  }
@@ -17,6 +17,7 @@ function item(overrides: Partial<AnnotationItem> = {}): AnnotationItem {
    origin: 'kobo',
    positionStatus: 'exact',
    chapterIndex: null,
+    highlightedAt: '2026-04-02T19:30:00.000Z',
    createdAt: '2026-04-02T19:30:00.000Z',
    ...overrides,
  }
@@ -157,21 +158,21 @@ describe('buildHighlightGroups by colour', () => {
 describe('buildHighlightGroups by day', () => {
  it('groups by the viewer time zone and puts the newest day first', () => {
    const groups = buildHighlightGroups(
-      [item({ id: 1, createdAt: '2026-04-02T12:00:00.000Z' }), item({ id: 2, createdAt: '2026-04-05T12:00:00.000Z' })],
+      [item({ id: 1, highlightedAt: '2026-04-02T12:00:00.000Z' }), item({ id: 2, highlightedAt: '2026-04-05T12:00:00.000Z' })],
      stats(),
      'day',
    )

    expect(groups.map((g) => g.label)).toEqual([
-      highlightDay(item({ createdAt: '2026-04-05T12:00:00.000Z' })),
-      highlightDay(item({ createdAt: '2026-04-02T12:00:00.000Z' })),
+      highlightDay(item({ highlightedAt: '2026-04-05T12:00:00.000Z' })),
+      highlightDay(item({ highlightedAt: '2026-04-02T12:00:00.000Z' })),
    ])
    expect(groups[0].total).toBe(1)
  })

  it('puts highlights made on the same day in one group', () => {
    const groups = buildHighlightGroups(
-      [item({ id: 1, createdAt: '2026-04-02T09:00:00.000Z' }), item({ id: 2, createdAt: '2026-04-02T11:00:00.000Z' })],
+      [item({ id: 1, highlightedAt: '2026-04-02T09:00:00.000Z' }), item({ id: 2, highlightedAt: '2026-04-02T11:00:00.000Z' })],
      stats(),
      'day',
    )
@@ -183,6 +184,6 @@ describe('buildHighlightGroups by day', () => {

 describe('highlightDay', () => {
  it('returns an empty key for an unparseable timestamp', () => {
-    expect(highlightDay(item({ createdAt: 'not a date' }))).toBe('')
+    expect(highlightDay(item({ highlightedAt: 'not a date' }))).toBe('')
  })
 })
@@ -24,7 +24,7 @@ export interface HighlightGroup {

 /** The day an annotation was made, in the viewer's own time zone. */
 export function highlightDay(annotation: AnnotationItem): string {
-  const date = new Date(annotation.createdAt)
+  const date = new Date(annotation.highlightedAt)
  if (Number.isNaN(date.getTime())) return ''
  const month = `${date.getMonth() + 1}`.padStart(2, '0')
  const day = `${date.getDate()}`.padStart(2, '0')
@@ -161,6 +161,7 @@ describe('ReaderSidebar', () => {
            origin: 'web',
            positionStatus: 'exact',
            chapterIndex: null,
+            highlightedAt: '2026-02-14T12:00:00.000Z',
            createdAt: '2026-02-14T12:00:00.000Z',
          },
          {
@@ -177,6 +178,7 @@ describe('ReaderSidebar', () => {
            origin: 'web',
            positionStatus: 'exact',
            chapterIndex: null,
+            highlightedAt: '2026-02-15T12:00:00.000Z',
            createdAt: '2026-02-15T12:00:00.000Z',
          },
        ],
@@ -237,6 +239,7 @@ describe('ReaderSidebar', () => {
            origin: 'web',
            positionStatus: 'exact',
            chapterIndex: null,
+            highlightedAt: '2026-02-13T12:00:00.000Z',
            createdAt: '2026-02-13T12:00:00.000Z',
          },
          {
@@ -253,6 +256,7 @@ describe('ReaderSidebar', () => {
            origin: 'web',
            positionStatus: 'exact',
            chapterIndex: null,
+            highlightedAt: '2026-02-16T12:00:00.000Z',
            createdAt: '2026-02-16T12:00:00.000Z',
          },
        ],
@@ -348,6 +352,7 @@ describe('ReaderSidebar', () => {
            origin: 'web',
            positionStatus: 'exact',
            chapterIndex: null,
+            highlightedAt: '2026-02-11T12:00:00.000Z',
            createdAt: '2026-02-11T12:00:00.000Z',
          },
        ],
@@ -27,6 +27,7 @@ function makeAnnotation(id: number, cfi = `epubcfi(/6/${id})`): Annotation {
    origin: 'web',
    positionStatus: 'exact',
    chapterIndex: null,
+    highlightedAt: '2026-01-01T00:00:00.000Z',
    createdAt: '2026-01-01T00:00:00.000Z',
  }
 }
@@ -18,6 +18,7 @@ function makeAnnotation(overrides: Partial<Annotation> = {}): Annotation {
    origin: 'web',
    positionStatus: 'exact',
    chapterIndex: null,
+    highlightedAt: '2026-01-01T00:00:00.000Z',
    createdAt: '2026-01-01T00:00:00.000Z',
    ...overrides,
  }
@@ -167,6 +167,7 @@ function makeAnnotation(id: number, overrides: Partial<AnnotationItem> = {}): An
    origin: 'web',
    positionStatus: 'exact',
    chapterIndex: null,
+    highlightedAt: '2026-01-01T00:00:00.000Z',
    createdAt: '2026-01-01T00:00:00.000Z',
    pdf: { page: 2, rect: { x: 10, y: 20, width: 30, height: 8 }, rects: [{ x: 10, y: 20, width: 30, height: 8 }] },
    ...overrides,
@@ -25,6 +25,7 @@ function makeAnnotation(overrides: Partial<AnnotationItem> = {}): AnnotationItem
    origin: 'web',
    positionStatus: 'exact',
    chapterIndex: null,
+    highlightedAt: '2026-01-01T00:00:00.000Z',
    createdAt: '2026-01-01T00:00:00.000Z',
    pdf: { page: 1, rect: { x: 10, y: 20, width: 30, height: 8 }, rects: [{ x: 10, y: 20, width: 30, height: 8 }] },
    ...overrides,
@@ -37,6 +37,7 @@ function makeAnnotation(id: number): AnnotationItem {
    origin: 'web',
    positionStatus: 'exact',
    chapterIndex: null,
+    highlightedAt: '2026-01-01T00:00:00.000Z',
    createdAt: '2026-01-01T00:00:00.000Z',
    pdf: PDF_POSITION,
  }
@@ -96,6 +96,7 @@ export interface AnnotationItem {
  origin: "web" | "koreader" | "kobo";
  positionStatus: AnnotationPositionStatus | null;
  chapterIndex: number | null;
+  highlightedAt: string;
  createdAt: string;
  /** Present for PDF highlights; null/absent for EPUB and device-synced formats. */
  pdf?: AnnotationPdfPosition | null;
@@ -0,0 +1,4 @@
+DROP INDEX "annotations_user_created_active_idx";--> statement-breakpoint
+ALTER TABLE "annotations" ADD COLUMN "source_created_at" timestamp with time zone;--> statement-breakpoint
+CREATE INDEX "annotations_user_book_created_active_idx" ON "annotations" USING btree ("user_id","book_id",coalesce("source_created_at", "created_at") desc,"id" DESC NULLS LAST) WHERE "annotations"."deleted_at" is null;--> statement-breakpoint
+CREATE INDEX "annotations_user_created_active_idx" ON "annotations" USING btree ("user_id",coalesce("source_created_at", "created_at") desc,"id" DESC NULLS LAST) WHERE "annotations"."deleted_at" is null;
@@ -603,6 +603,13 @@
      "when": 1788321273908,
      "tag": "0085_add_authentication_method",
      "breakpoints": true
+    },
+    {
+      "idx": 86,
+      "version": "7",
+      "when": 1788884825211,
+      "tag": "0086_add_annotation_source_created_at",
+      "breakpoints": true
    }
  ]
 }
@@ -408,6 +408,7 @@ export const annotations = pgTable(
    // deviceCreatedAt doubles as the KOReader-side identity datetime for synced annotations.
    deviceCreatedAt: varchar('device_created_at', { length: 19 }),
    deviceUpdatedAt: varchar('device_updated_at', { length: 19 }),
+    sourceCreatedAt: timestamp('source_created_at', { withTimezone: true }),
    createdAt: timestamp('created_at', { withTimezone: true }).defaultNow().notNull(),
    updatedAt: timestamp('updated_at', { withTimezone: true })
      .notNull()
@@ -425,7 +426,10 @@ export const annotations = pgTable(
    // The annotations hub is an infinite stream ordered newest-first over everything a
    // user owns, so its default query sorts the whole set without this.
    index('annotations_user_created_active_idx')
-      .on(t.userId, t.createdAt.desc(), t.id.desc())
+      .on(t.userId, sql`coalesce(${t.sourceCreatedAt}, ${t.createdAt}) desc`, t.id.desc())
+      .where(sql`${t.deletedAt} is null`),
+    index('annotations_user_book_created_active_idx')
+      .on(t.userId, t.bookId, sql`coalesce(${t.sourceCreatedAt}, ${t.createdAt}) desc`, t.id.desc())
      .where(sql`${t.deletedAt} is null`),
    check('annotations_style_chk', sql`${t.style} in ('highlight', 'underline', 'strikethrough', 'squiggly', 'invert')`),
    check('annotations_origin_chk', sql`${t.origin} in ('web', 'koreader', 'kobo')`),
@@ -18,6 +18,7 @@ function makeRow(overrides: Partial<HubAnnotationRow> = {}): HubAnnotationRow {
    deletedAt: null,
    deviceCreatedAt: null,
    deviceUpdatedAt: null,
+    sourceCreatedAt: null,
    createdAt: new Date('2026-06-01T10:00:00Z'),
    updatedAt: new Date('2026-06-01T10:00:00Z'),
    cfi: 'epubcfi(/6/2!/4/2,/1:0,/1:5)',
@@ -26,6 +27,7 @@ function makeRow(overrides: Partial<HubAnnotationRow> = {}): HubAnnotationRow {
    bookTitle: 'Test Book',
    jumpFileId: 10,
    pageno: null,
+    xpointer: null,
    ...overrides,
  } as HubAnnotationRow;
 }
@@ -59,7 +61,7 @@ describe('AnnotationExportService', () => {

    expect(result.contentType).toContain('csv');
    expect(result.content).toContain('"He said ""hi"", twice\nand left"');
-    expect(result.content.split('\r\n')[0]).toBe('book,chapter,text,note,color,style,origin,createdAt');
+    expect(result.content.split('\r\n')[0]).toBe('book,chapter,text,note,color,style,origin,page,cfi,xpointer,highlightedAt,createdAt');
  });

  it('renders JSON with stable fields', () => {
@@ -75,4 +77,31 @@ describe('AnnotationExportService', () => {
      cfi: 'epubcfi(/6/2!/4/2,/1:0,/1:5)',
    });
  });
+
+  it('exports source time and KOReader position while preserving ingestion time', () => {
+    const result = service.export(
+      [
+        makeRow({
+          origin: 'koreader',
+          sourceCreatedAt: new Date('2026-01-15T16:30:00.000Z'),
+          createdAt: new Date('2026-09-06T17:10:19.332Z'),
+          cfi: null,
+          pageno: 123,
+          xpointer: '/body/DocFragment[5]/body/p[2]/text().0',
+        }),
+      ],
+      'json',
+      'library',
+    );
+
+    expect(JSON.parse(result.content)).toEqual([
+      expect.objectContaining({
+        page: 123,
+        cfi: null,
+        xpointer: '/body/DocFragment[5]/body/p[2]/text().0',
+        highlightedAt: '2026-01-15T16:30:00.000Z',
+        createdAt: '2026-09-06T17:10:19.332Z',
+      }),
+    ]);
+  });
 });
@@ -62,13 +62,13 @@ export class AnnotationExportService {
        .join('\n');
      lines.push(quote);
      if (row.note) lines.push('', `Note: ${row.note}`);
-      lines.push('', `<sub>${row.style}, ${row.color}, ${row.origin}, ${row.createdAt.toISOString().slice(0, 10)}</sub>`, '');
+      lines.push('', `<sub>${row.style}, ${row.color}, ${row.origin}, ${this.highlightedAt(row).toISOString().slice(0, 10)}</sub>`, '');
    }
    return lines.join('\n');
  }

  private toCsv(rows: HubAnnotationRow[]): string {
-    const header = ['book', 'chapter', 'text', 'note', 'color', 'style', 'origin', 'createdAt'];
+    const header = ['book', 'chapter', 'text', 'note', 'color', 'style', 'origin', 'page', 'cfi', 'xpointer', 'highlightedAt', 'createdAt'];
    const escape = (value: string | null): string => {
      const raw = value ?? '';
      return /[",\n\r]/.test(raw) ? `"${raw.replace(/"/g, '""')}"` : raw;
@@ -84,6 +84,10 @@ export class AnnotationExportService {
          escape(row.color),
          escape(row.style),
          escape(row.origin),
+          escape(row.pageno == null ? null : String(row.pageno)),
+          escape(row.cfi),
+          escape(row.xpointer),
+          escape(this.highlightedAt(row).toISOString()),
          escape(row.createdAt.toISOString()),
        ].join(','),
      );
@@ -103,11 +107,18 @@ export class AnnotationExportService {
        color: row.color,
        style: row.style,
        origin: row.origin,
+        page: row.pageno,
        cfi: row.cfi,
+        xpointer: row.xpointer,
+        highlightedAt: this.highlightedAt(row).toISOString(),
        createdAt: row.createdAt.toISOString(),
      })),
      null,
      2,
    );
  }
+
+  private highlightedAt(row: HubAnnotationRow): Date {
+    return row.sourceCreatedAt ?? row.createdAt;
+  }
 }
@@ -20,6 +20,7 @@ function makeHubRow(overrides: Record<string, unknown> = {}) {
    deletedAt: null,
    deviceCreatedAt: null,
    deviceUpdatedAt: null,
+    sourceCreatedAt: null,
    createdAt: new Date('2026-01-10T00:00:00Z'),
    updatedAt: new Date('2026-01-10T00:00:00Z'),
    bookTitle: 'A Book',
@@ -27,6 +28,7 @@ function makeHubRow(overrides: Record<string, unknown> = {}) {
    jumpFileId: 9,
    jumpFileFormat: 'fb2',
    pageno: null,
+    xpointer: null,
    ...overrides,
  };
 }
@@ -204,6 +206,27 @@ describe('AnnotationHubService', () => {

      expect(result.items[0]).toMatchObject({ cfi: null, jumpFileId: 9, jumpFileFormat: 'pdf', pageno: 4 });
    });
+
+    it('returns source highlight time separately from ingestion time', async () => {
+      const { service, annotationRepo } = makeService();
+      annotationRepo.findHubPaginated.mockResolvedValueOnce({
+        items: [
+          makeHubRow({
+            origin: 'koreader',
+            sourceCreatedAt: new Date('2026-01-15T16:30:00.000Z'),
+            createdAt: new Date('2026-09-06T17:10:19.332Z'),
+          }),
+        ],
+        total: 1,
+      });
+
+      const result = await service.list(10, {});
+
+      expect(result.items[0]).toMatchObject({
+        highlightedAt: '2026-01-15T16:30:00.000Z',
+        createdAt: '2026-09-06T17:10:19.332Z',
+      });
+    });
  });

  describe('listBooks', () => {
@@ -171,6 +171,7 @@ export class AnnotationHubService {
        jumpFileId: null,
        jumpFileFormat: null,
        pageno: null,
+        xpointer: null,
      },
    );
  }
@@ -266,6 +267,7 @@ export class AnnotationHubService {
      origin: row.origin,
      positionStatus: (row.cfi != null || row.cfiStatus != null ? (row.cfiStatus ?? 'exact') : null) as AnnotationHubItem['positionStatus'],
      chapterIndex: typeof chapterIndex === 'number' ? chapterIndex : null,
+      highlightedAt: (row.sourceCreatedAt ?? row.createdAt).toISOString(),
      createdAt: row.createdAt.toISOString(),
      bookTitle: row.bookTitle,
      author: row.author,
@@ -350,6 +350,27 @@ export class AnnotationSyncRepository {
    await ex.update(annotations).set({ deviceUpdatedAt }).where(eq(annotations.id, annotationId));
  }

+  async setSourceCreatedAtSilent(annotationId: number, sourceCreatedAt: Date, ex: Executor = this.db): Promise<void> {
+    await ex
+      .update(annotations)
+      .set({ sourceCreatedAt })
+      .where(and(eq(annotations.id, annotationId), isNull(annotations.sourceCreatedAt)));
+  }
+
+  async setSourceCreatedAtsSilent(entries: { annotationId: number; sourceCreatedAt: Date }[], ex: Executor = this.db): Promise<void> {
+    if (entries.length === 0) return;
+    const values = sql.join(
+      entries.map((entry) => sql`(${entry.annotationId}::int, ${entry.sourceCreatedAt}::timestamptz)`),
+      sql`, `,
+    );
+    await ex.execute(sql`
+      update ${annotations} set source_created_at = v.source_created_at
+      from (values ${values}) as v(annotation_id, source_created_at)
+      where ${annotations.id} = v.annotation_id
+        and ${annotations.sourceCreatedAt} is null
+    `);
+  }
+
  async bumpVersion(annotationId: number, ex: Executor = this.db): Promise<number> {
    const [row] = await ex
      .update(annotations)
@@ -14,6 +14,7 @@ const TX = Symbol('tx');
 function makeIncoming(overrides: Partial<IncomingDeviceAnnotation> = {}): IncomingDeviceAnnotation {
  return {
    datetime: '2026-06-01 21:14:03',
+    sourceCreatedAt: new Date('2026-06-02T03:14:03.000Z'),
    datetimeUpdated: null,
    drawer: 'lighten',
    color: 'yellow',
@@ -43,6 +44,7 @@ function makeAnnotationRow(overrides: Record<string, unknown> = {}) {
    deletedAt: null,
    deviceCreatedAt: '2026-06-01 21:14:03',
    deviceUpdatedAt: null,
+    sourceCreatedAt: null,
    createdAt: new Date('2026-06-01T21:14:03Z'),
    updatedAt: new Date('2026-06-01T21:14:03Z'),
    ...overrides,
@@ -109,6 +111,8 @@ function makeRepo(): RepoMock {
    setDeviceIdentitySilent: vi.fn().mockResolvedValue(undefined),
    setDeviceIdentitiesSilent: vi.fn().mockResolvedValue(undefined),
    setDeviceUpdatedAtSilent: vi.fn().mockResolvedValue(undefined),
+    setSourceCreatedAtSilent: vi.fn().mockResolvedValue(undefined),
+    setSourceCreatedAtsSilent: vi.fn().mockResolvedValue(undefined),
    bumpVersion: vi.fn().mockResolvedValue(5),
    softDeleteById: vi.fn().mockResolvedValue(undefined),
    setDeleteAcked: vi.fn().mockResolvedValue(undefined),
@@ -180,6 +184,7 @@ describe('AnnotationSyncService', () => {
        color: '#84CC16',
        version: 1,
        deviceCreatedAt: '2026-06-01 21:14:03',
+        sourceCreatedAt: new Date('2026-06-02T03:14:03.000Z'),
      });
      expect(position).toMatchObject({
        bookFileId: BOOK_FILE_ID,
@@ -296,6 +301,7 @@ describe('AnnotationSyncService', () => {
      const result = await ingest(service, [makeIncoming()]);

      expect(result).toMatchObject({ unchanged: 1, updated: 0, created: 0 });
+      expect(repo.setSourceCreatedAtSilent).toHaveBeenCalledWith(100, new Date('2026-06-02T03:14:03.000Z'), TX);
      expect(repo.touchState).toHaveBeenCalled();
      expect(repo.applyContentPatch).not.toHaveBeenCalled();
    });
@@ -444,9 +450,20 @@ describe('AnnotationSyncService', () => {
  });

  describe('detectDeviceDeletions', () => {
-    const detect = (presentKeys: { k: string; dt: string }[]) =>
+    const detect = (presentKeys: { k: string; dt: string; sourceCreatedAt?: Date | null }[]) =>
      service.detectDeviceDeletions({ userId: USER_ID, source: 'koreader', deviceId: DEVICE_ID, bookId: BOOK_ID, presentKeys });

+    it('backfills source creation times from a complete key set without changing annotation versions', async () => {
+      const state = makeStateRow();
+      repo.findStatesForDeviceBook.mockResolvedValue([{ state, annotation: makeAnnotationRow() }]);
+      const sourceCreatedAt = new Date('2026-06-02T03:14:03.000Z');
+
+      await detect([{ k: state.externalKey as string, dt: state.externalCreatedAt as string, sourceCreatedAt }]);
+
+      expect(repo.setSourceCreatedAtsSilent).toHaveBeenCalledWith([{ annotationId: 100, sourceCreatedAt }], TX);
+      expect(repo.applyContentPatch).not.toHaveBeenCalled();
+    });
+
    it('soft-deletes annotations missing from the device key set and acks this device', async () => {
      repo.findStatesForDeviceBook.mockResolvedValue([{ state: makeStateRow(), annotation: makeAnnotationRow() }]);

@@ -29,6 +29,7 @@ export interface IncomingDeviceAnnotation {
   */
  externalKey?: string;
  datetime: string;
+  sourceCreatedAt?: Date | null;
  datetimeUpdated?: string | null;
  drawer?: string;
  color?: string | null;
@@ -163,6 +164,7 @@ export class AnnotationSyncService {
        result.skippedDeleted += 1;
        return;
      }
+      await this.backfillSourceCreatedAt(annotation, incoming, source, tx);
      const changed = await this.applyIncomingContent(annotation, incoming, bookFileId, tx);
      if (changed) {
        await this.syncRepo.updateState(deviceState.id, { lastAppliedVersion: changed.newVersion }, tx);
@@ -192,6 +194,7 @@ export class AnnotationSyncService {
        result.skippedDeleted += 1;
        return;
      }
+      await this.backfillSourceCreatedAt(crossDevice.annotation, incoming, source, tx);
      const state = await this.syncRepo.insertState(
        {
          annotationId: crossDevice.annotation.id,
@@ -240,6 +243,8 @@ export class AnnotationSyncService {
        return;
      }

+      await this.backfillSourceCreatedAt(annotation, incoming, source, tx);
+
      const isMove = !exact && position != null && position.pos0 !== incoming.pos0;
      let version = annotation.version;
      if (isMove) {
@@ -287,6 +292,7 @@ export class AnnotationSyncService {
        version: 1,
        deviceCreatedAt: incoming.datetime,
        deviceUpdatedAt: incoming.datetimeUpdated ?? null,
+        sourceCreatedAt: incoming.sourceCreatedAt ?? null,
      },
      {
        bookFileId,
@@ -309,6 +315,16 @@ export class AnnotationSyncService {
    result.created += 1;
  }

+  private async backfillSourceCreatedAt(
+    annotation: AnnotationRow,
+    incoming: IncomingDeviceAnnotation,
+    source: AnnotationSyncSource,
+    tx: DbTx,
+  ): Promise<void> {
+    if (annotation.origin !== source || annotation.sourceCreatedAt != null || incoming.sourceCreatedAt == null) return;
+    await this.syncRepo.setSourceCreatedAtSilent(annotation.id, incoming.sourceCreatedAt, tx);
+  }
+
  /**
   * Applies device content only when the device actually made a new edit since the last
   * one we ingested (device-clock comparison, no cross-clock skew). Style and color use
@@ -547,10 +563,22 @@ export class AnnotationSyncService {
  }): Promise<number> {
    const present = new Set(params.presentKeys.map((entry) => entry.k));
    const presentDatetimes = new Set(params.presentKeys.map((entry) => entry.dt));
+    const sourceCreatedAtByKey = new Map(
+      params.presentKeys.flatMap((entry) => (entry.sourceCreatedAt ? [[entry.k, entry.sourceCreatedAt] as const] : [])),
+    );
    let deletedCount = 0;

    await this.syncRepo.transaction(async (tx) => {
      const states = await this.syncRepo.findStatesForDeviceBook(params.userId, params.source, params.deviceId, params.bookId, tx);
+      await this.syncRepo.setSourceCreatedAtsSilent(
+        states.flatMap(({ state, annotation }) => {
+          const sourceCreatedAt = sourceCreatedAtByKey.get(state.externalKey);
+          return annotation.origin === params.source && annotation.sourceCreatedAt == null && sourceCreatedAt
+            ? [{ annotationId: annotation.id, sourceCreatedAt }]
+            : [];
+        }),
+        tx,
+      );
      for (const { state, annotation } of states) {
        if (annotation.deletedAt) continue;
        if (present.has(state.externalKey)) continue;
@@ -747,6 +775,7 @@ export class AnnotationSyncService {
 export interface DeviceKeyEntry {
  k: string;
  dt: string;
+  sourceCreatedAt?: Date | null;
 }

 export interface PushDownSets {
@@ -1,4 +1,6 @@
 import { Test } from '@nestjs/testing';
+import type { SQL } from 'drizzle-orm';
+import { PgDialect } from 'drizzle-orm/pg-core';

 import { DB } from '../../db';
 import { AnnotationRepository } from './annotation.repository';
@@ -20,12 +22,18 @@ function makeRow(overrides?: Record<string, unknown>) {
    deletedAt: null,
    deviceCreatedAt: null,
    deviceUpdatedAt: null,
+    sourceCreatedAt: null,
    createdAt: new Date('2026-01-01T00:00:00Z'),
    updatedAt: new Date('2026-01-01T00:00:00Z'),
    ...overrides,
  };
 }

+function compileSql(fragments: unknown[]): string {
+  const dialect = new PgDialect();
+  return fragments.map((fragment) => dialect.sqlToQuery(fragment as SQL).sql).join(' ');
+}
+
 type ChainQuery = Record<string, ReturnType<typeof vi.fn>> & {
  then: (resolve: (value: unknown) => unknown, reject?: (error: unknown) => unknown) => Promise<unknown>;
 };
@@ -92,6 +100,7 @@ describe('AnnotationRepository', () => {
      expect(db.select).toHaveBeenCalled();
      expect(db._queries[0].leftJoin).toHaveBeenCalled();
      expect(db._queries[0].orderBy).toHaveBeenCalled();
+      expect(compileSql(db._queries[0].orderBy.mock.calls[0])).toContain('coalesce("annotations"."source_created_at", "annotations"."created_at")');
      expect(result).toEqual(rows);
    });

@@ -524,7 +533,10 @@ describe('AnnotationRepository', () => {
      expect(result.items).toHaveLength(1);
      expect(result.items[0].jumpFileFormat).toBe('mobi');
      expect(db.select.mock.calls[0][0]).toHaveProperty('jumpFileFormat');
+      expect(db.select.mock.calls[0][0]).toHaveProperty('xpointer');
      expect(db._queries[0].where).toHaveBeenCalled();
+      expect(compileSql(db._queries[0].where.mock.calls[0])).toContain('coalesce("annotations"."source_created_at", "annotations"."created_at")');
+      expect(compileSql(db._queries[0].orderBy.mock.calls[0])).toContain('coalesce("annotations"."source_created_at", "annotations"."created_at")');
    });

    it('orders by book title when sort.by is book', async () => {
@@ -580,6 +592,8 @@ describe('AnnotationRepository', () => {
      });

      expect(rows).toHaveLength(2);
+      expect(db.select.mock.calls[0][0]).toHaveProperty('xpointer');
+      expect(compileSql(db._queries[0].orderBy.mock.calls[0])).toContain('coalesce("annotations"."source_created_at", "annotations"."created_at")');
    });
  });

@@ -48,7 +48,16 @@ export type AnnotationWithCfi = AnnotationRow & {
  pdfPos0?: string | null;
  pdfStatus?: string | null;
 };
-export type HubAnnotationRow = AnnotationWithCfi & { bookTitle: string | null; author: string | null; jumpFileFormat: string | null };
+export type HubAnnotationRow = AnnotationWithCfi & {
+  bookTitle: string | null;
+  author: string | null;
+  jumpFileFormat: string | null;
+  xpointer: string | null;
+};
+
+function highlightedAt(): SQL<Date> {
+  return sql<Date>`coalesce(${annotations.sourceCreatedAt}, ${annotations.createdAt})`;
+}

 export interface HubFilters {
  bookId?: number;
@@ -142,6 +151,9 @@ export class AnnotationRepository {
      pageno: sql<
        number | null
      >`(select (ap3.extras ->> 'pageno')::int from annotation_positions ap3 where ap3.annotation_id = ${annotations.id} and ap3.format in ('xpointer', 'pdf') limit 1)`,
+      xpointer: sql<
+        string | null
+      >`(select ap4.pos0 from annotation_positions ap4 where ap4.annotation_id = ${annotations.id} and ap4.format = 'xpointer' limit 1)`,
    };
  }

@@ -173,7 +185,7 @@ export class AnnotationRepository {
  async findByBookId(bookId: number, userId: number): Promise<AnnotationWithCfi[]> {
    return this.selectWithCfi()
      .where(and(...this.baseConditions(bookId, userId)))
-      .orderBy(asc(annotations.createdAt));
+      .orderBy(asc(highlightedAt()));
  }

  async findById(bookId: number, annotationId: number, userId: number): Promise<AnnotationWithCfi | null> {
@@ -256,7 +268,7 @@ export class AnnotationRepository {
          // The step after `/6` in an epub CFI addresses the spine itemref. Kept raw here and
          // converted to a spine index in foldChapterRows, where it can be tested.
          cfiSpineStep: sql<number | null>`min(nullif(substring(${annotationPositions.pos0} from 'epubcfi[(]/6/([0-9]+)'), '')::int)`,
-          firstCreatedAt: sql<Date>`min(${annotations.createdAt})`,
+          firstCreatedAt: sql<Date>`min(${highlightedAt()})`,
        })
        .from(annotations)
        .leftJoin(annotationPositions, cfiJoin)
@@ -264,7 +276,7 @@ export class AnnotationRepository {
        .groupBy(annotations.chapterTitle, annotations.color),
      this.db
        .select({
-          day: sql<string>`to_char(${annotations.createdAt} at time zone 'UTC', 'YYYY-MM-DD')`,
+          day: sql<string>`to_char(${highlightedAt()} at time zone 'UTC', 'YYYY-MM-DD')`,
          origin: annotations.origin,
          count: count(),
        })
@@ -421,7 +433,7 @@ export class AnnotationRepository {
    // The hub groups a page at a time, so a grouped run only ever lands whole when the
    // rows arrive already ordered by the grouping key. Every non-date sort therefore
    // falls back to newest-first inside the group.
-    const withinGroup = [desc(annotations.createdAt), desc(annotations.id)];
+    const withinGroup = [desc(highlightedAt()), desc(annotations.id)];
    const orderBy =
      sort.by === 'book'
        ? [direction(bookMetadata.title), ...withinGroup]
@@ -429,7 +441,7 @@ export class AnnotationRepository {
          ? [direction(annotations.color), ...withinGroup]
          : sort.by === 'origin'
            ? [direction(annotations.origin), ...withinGroup]
-            : [direction(annotations.createdAt), direction(annotations.id)];
+            : [direction(highlightedAt()), direction(annotations.id)];
    const offset = (page - 1) * pageSize;

    const [items, totalResult] = await Promise.all([
@@ -483,7 +495,7 @@ export class AnnotationRepository {
      .leftJoin(bookMetadata, eq(bookMetadata.bookId, annotations.bookId))
      .leftJoin(books, eq(books.id, annotations.bookId))
      .where(and(...conditions))
-      .orderBy(asc(bookMetadata.title), asc(annotations.chapterTitle), asc(annotations.createdAt))
+      .orderBy(asc(bookMetadata.title), asc(annotations.chapterTitle), asc(highlightedAt()))
      .limit(limit);
    return rows as HubAnnotationRow[];
  }
@@ -546,12 +558,12 @@ export class AnnotationRepository {
  async getHubActivityWeeks(userId: number, filters: HubFilters, since: Date) {
    return this.db
      .select({
-        weekStart: sql<string>`to_char(date_trunc('week', ${annotations.createdAt} at time zone 'UTC'), 'YYYY-MM-DD')`,
+        weekStart: sql<string>`to_char(date_trunc('week', ${highlightedAt()} at time zone 'UTC'), 'YYYY-MM-DD')`,
        origin: annotations.origin,
        count: count(),
      })
      .from(annotations)
-      .where(and(...this.buildHubConditions(userId, filters), gte(annotations.createdAt, since)))
+      .where(and(...this.buildHubConditions(userId, filters), gte(highlightedAt(), since)))
      .groupBy(sql`1`, annotations.origin)
      .orderBy(sql`1`);
  }
@@ -613,7 +625,7 @@ export class AnnotationRepository {
      .leftJoin(bookMetadata, eq(bookMetadata.bookId, annotations.bookId))
      .where(and(...conditions))
      .groupBy(annotations.bookId, bookMetadata.title)
-      .orderBy(...(params.order === 'count' ? [desc(count()), asc(bookMetadata.title)] : [desc(max(annotations.createdAt)), asc(bookMetadata.title)]))
+      .orderBy(...(params.order === 'count' ? [desc(count()), asc(bookMetadata.title)] : [desc(max(highlightedAt())), asc(bookMetadata.title)]))
      .limit(params.limit);
  }

@@ -685,8 +697,8 @@ export class AnnotationRepository {
        sql`exists (select 1 from ${annotationPositions} where ${annotationPositions.annotationId} = ${annotations.id} and ${annotationPositions.format} = 'cfi' and ${annotationPositions.status} <> 'exact')`,
      );
    }
-    if (filters.dateFrom) conditions.push(gte(annotations.createdAt, filters.dateFrom));
-    if (filters.dateTo) conditions.push(lte(annotations.createdAt, filters.dateTo));
+    if (filters.dateFrom) conditions.push(gte(highlightedAt(), filters.dateFrom));
+    if (filters.dateTo) conditions.push(lte(highlightedAt(), filters.dateTo));
    return conditions;
  }

@@ -722,10 +734,10 @@ export class AnnotationRepository {
      conditions.push(eq(annotations.chapterTitle, filters.chapter));
    }
    if (filters.dateFrom) {
-      conditions.push(gte(annotations.createdAt, filters.dateFrom));
+      conditions.push(gte(highlightedAt(), filters.dateFrom));
    }
    if (filters.dateTo) {
-      conditions.push(lte(annotations.createdAt, filters.dateTo));
+      conditions.push(lte(highlightedAt(), filters.dateTo));
    }
    if (filters.hasNote) {
      conditions.push(sql`${annotations.note} is not null and ${annotations.note} <> ''`);
@@ -767,6 +779,6 @@ export class AnnotationRepository {
        direction(annotations.id),
      ];
    }
-    return [direction(annotations.createdAt), direction(annotations.id)];
+    return [direction(highlightedAt()), direction(annotations.id)];
  }
 }
@@ -54,6 +54,7 @@ function makeAnnotationRow(overrides?: Record<string, unknown>) {
    deletedAt: null,
    deviceCreatedAt: null,
    deviceUpdatedAt: null,
+    sourceCreatedAt: null,
    createdAt: new Date('2026-01-01T00:00:00Z'),
    updatedAt: new Date('2026-01-01T00:00:00Z'),
    ...overrides,
@@ -559,9 +560,23 @@ describe('AnnotationService', () => {
      expect(dto.style).toBe('underline');
      expect(dto.note).toBe('a note');
      expect(dto.chapterTitle).toBe('Intro');
+      expect(dto.highlightedAt).toEqual(new Date('2026-03-01T00:00:00Z'));
      expect(dto.createdAt).toEqual(new Date('2026-03-01T00:00:00Z'));
    });

+    it('maps source creation and ingestion timestamps independently', () => {
+      const row = makeAnnotationRow({
+        origin: 'koreader',
+        sourceCreatedAt: new Date('2026-01-15T16:30:00.000Z'),
+        createdAt: new Date('2026-09-06T17:10:19.332Z'),
+      });
+
+      const dto = AnnotationResponseDto.from(row as never);
+
+      expect(dto.highlightedAt).toEqual(new Date('2026-01-15T16:30:00.000Z'));
+      expect(dto.createdAt).toEqual(new Date('2026-09-06T17:10:19.332Z'));
+    });
+
    it('parses pdf geometry and derives positionStatus for a pdf row', () => {
      const geometry = {
        page: 2,
@@ -67,6 +67,7 @@ export class AnnotationService {
          origin: dto.origin as 'web' | 'koreader' | 'kobo',
          positionStatus: dto.positionStatus as AnnotationListResponse['items'][number]['positionStatus'],
          chapterIndex: dto.chapterIndex,
+          highlightedAt: dto.highlightedAt.toISOString(),
          createdAt: dto.createdAt instanceof Date ? dto.createdAt.toISOString() : String(dto.createdAt),
          pdf: dto.pdf,
        };
@@ -16,6 +16,7 @@ export class AnnotationResponseDto {
  origin!: string;
  positionStatus!: string | null;
  chapterIndex!: number | null;
+  highlightedAt!: Date;
  createdAt!: Date;
  pdf!: AnnotationPdfPosition | null;

@@ -36,6 +37,7 @@ export class AnnotationResponseDto {
    dto.positionStatus = resolvePositionStatus(row);
    const chapterIndex = (row.cfiExtras as { chapterIndex?: number } | null)?.chapterIndex;
    dto.chapterIndex = typeof chapterIndex === 'number' ? chapterIndex : null;
+    dto.highlightedAt = row.sourceCreatedAt ?? row.createdAt;
    dto.createdAt = row.createdAt;
    return dto;
  }
@@ -5,15 +5,15 @@ import type { RequestUser } from '../../common/types/request-user';
 import type { AnnotationSyncService } from '../annotation/annotation-sync.service';
 import type { PositionConverterService } from '../position-converter/position-converter.service';
 import type { AnnotationExchangeAckDto, AnnotationExchangeDto } from './dto';
-import { KoreaderAnnotationExchangeService } from './koreader-annotation-exchange.service';
+import { KoreaderAnnotationExchangeService, parseKoreaderSourceCreatedAt } from './koreader-annotation-exchange.service';
 import type { KoreaderRepository } from './koreader.repository';

 const DEVICE_ID = 'device-1234';
 const HASH_A = 'a'.repeat(32);
 const HASH_B = 'b'.repeat(32);

-function makeUser(): RequestUser {
-  return { id: 7, settings: {} } as unknown as RequestUser;
+function makeUser(timezone = 'UTC'): RequestUser {
+  return { id: 7, settings: { timezone } } as unknown as RequestUser;
 }

 function makeAnnotationRow(overrides: Record<string, unknown> = {}) {
@@ -31,6 +31,7 @@ function makeAnnotationRow(overrides: Record<string, unknown> = {}) {
    deletedAt: null,
    deviceCreatedAt: null,
    deviceUpdatedAt: null,
+    sourceCreatedAt: null,
    createdAt: new Date('2026-06-08T10:00:00Z'),
    updatedAt: new Date('2026-06-09T11:30:00Z'),
    ...overrides,
@@ -106,6 +107,33 @@ describe('KoreaderAnnotationExchangeService', () => {
    return { hash: HASH_A, keys: [], keysComplete: true, changes: [], ...overrides } as AnnotationExchangeDto['books'][number];
  }

+  it('converts KOReader wall-clock dates with the user timezone, including historical DST', () => {
+    expect(parseKoreaderSourceCreatedAt('2026-01-15 09:30:00', 'America/Denver')).toEqual(new Date('2026-01-15T16:30:00.000Z'));
+    expect(parseKoreaderSourceCreatedAt('2026-07-15 09:30:00', 'America/Denver')).toEqual(new Date('2026-07-15T15:30:00.000Z'));
+  });
+
+  it('rejects impossible or nonexistent KOReader wall-clock dates', () => {
+    expect(parseKoreaderSourceCreatedAt('2026-02-30 09:30:00', 'UTC')).toBeNull();
+    expect(parseKoreaderSourceCreatedAt('2026-03-08 02:30:00', 'America/Denver')).toBeNull();
+  });
+
+  it('passes the normalized source date into annotation ingest', async () => {
+    const change = {
+      datetime: '2026-01-15 09:30:00',
+      drawer: 'lighten',
+      posFormat: 'xpointer',
+      pos0: '/body/DocFragment[1]',
+    } as AnnotationExchangeDto['books'][number]['changes'][number];
+
+    await service.exchange(makeUser('America/Denver'), makeExchangeDto([makeBook({ changes: [change] })]));
+
+    expect(annotationSync.ingestDeviceAnnotations).toHaveBeenCalledWith(
+      expect.objectContaining({
+        annotations: [expect.objectContaining({ datetime: change.datetime, sourceCreatedAt: new Date('2026-01-15T16:30:00.000Z') })],
+      }),
+    );
+  });
+
  it('reports unmatched hashes without processing them', async () => {
    const response = await service.exchange(makeUser(), makeExchangeDto([makeBook({ hash: HASH_B })]));

@@ -137,7 +165,12 @@ describe('KoreaderAnnotationExchangeService', () => {
    await service.exchange(makeUser(), makeExchangeDto([makeBook({ keys })]));

    expect(annotationSync.detectDeviceDeletions).toHaveBeenCalledWith(
-      expect.objectContaining({ userId: 7, deviceId: DEVICE_ID, bookId: 20, presentKeys: keys }),
+      expect.objectContaining({
+        userId: 7,
+        deviceId: DEVICE_ID,
+        bookId: 20,
+        presentKeys: [expect.objectContaining({ ...keys[0], sourceCreatedAt: new Date('2026-06-01T21:14:03.000Z') })],
+      }),
    );
  });

@@ -1,7 +1,9 @@
 import { BadRequestException, Injectable, Logger } from '@nestjs/common';
+import { formatInTimeZone, fromZonedTime } from 'date-fns-tz';

 import type { RequestUser } from '../../common/types/request-user';
 import { sanitizeLogValue } from '../../common/utils/log-sanitize.utils';
+import { resolveTimeZone } from '../../common/utils/timezone.utils';
 import type { AnnotationPosition, AnnotationRow } from '../../db/schema';
 import { drawerFromStyle, koreaderColorFromHex } from '../annotation/annotation-style-map';
 import { AnnotationSyncService, formatDeviceDatetime, type IncomingDeviceAnnotation, type IngestResult } from '../annotation/annotation-sync.service';
@@ -15,9 +17,20 @@ const ACK_EVENT = 'koreader.annotation_exchange_ack';
 const MAX_CHANGES_PER_REQUEST = 50;
 const PUSH_DOWN_PAGE = 100;
 const CONVERSION_BUDGET_PER_REQUEST = 20;
+const DEVICE_DATETIME_FORMAT = 'yyyy-MM-dd HH:mm:ss';

 type DevicePositionsByFormat = { pdf?: AnnotationPosition; xpointer?: AnnotationPosition; cfi?: AnnotationPosition };

+export function parseKoreaderSourceCreatedAt(datetime: string, timeZone: string): Date | null {
+  try {
+    const parsed = fromZonedTime(datetime, timeZone);
+    if (Number.isNaN(parsed.getTime())) return null;
+    return formatInTimeZone(parsed, timeZone, DEVICE_DATETIME_FORMAT) === datetime ? parsed : null;
+  } catch {
+    return null;
+  }
+}
+
 export interface ExchangeAddEntry {
  serverId: number;
  version: number;
@@ -102,6 +115,7 @@ export class KoreaderAnnotationExchangeService {
      const hashes = [...new Set(dto.books.map((book) => book.hash.toLowerCase()))];
      const matches = await this.koreaderRepo.resolveBookFilesByHashes(hashes, accessibleLibraryIds, user.id);
      const deviceClockOffsetMs = this.deviceClockOffsetMs(dto.deviceTime);
+      const timeZone = resolveTimeZone((user.settings as { timezone?: unknown } | undefined)?.timezone, 'UTC');

      const results: ExchangeBookResult[] = [];
      const unmatched: string[] = [];
@@ -114,7 +128,7 @@ export class KoreaderAnnotationExchangeService {
          unmatched.push(hash);
          continue;
        }
-        const result = await this.exchangeBook(user.id, dto.deviceId, hash, match.bookId, match.bookFileId, book, deviceClockOffsetMs);
+        const result = await this.exchangeBook(user.id, dto.deviceId, hash, match.bookId, match.bookFileId, book, deviceClockOffsetMs, timeZone);
        pushedTotal += result.toApply.add.length + result.toApply.edit.length + result.toApply.delete.length;
        results.push(result);
      }
@@ -202,6 +216,7 @@ export class KoreaderAnnotationExchangeService {
    bookFileId: number,
    book: ExchangeBookDto,
    deviceClockOffsetMs: number,
+    timeZone: string,
  ): Promise<ExchangeBookResult> {
    const ingest = await this.annotationSync.ingestDeviceAnnotations({
      userId,
@@ -209,7 +224,7 @@ export class KoreaderAnnotationExchangeService {
      deviceId,
      bookId,
      bookFileId,
-      annotations: book.changes.map((change) => this.toIncoming(change)),
+      annotations: book.changes.map((change) => this.toIncoming(change, timeZone)),
    });

    let deviceDeleted = 0;
@@ -219,7 +234,10 @@ export class KoreaderAnnotationExchangeService {
        source: 'koreader',
        deviceId,
        bookId,
-        presentKeys: book.keys,
+        presentKeys: book.keys.map((entry) => ({
+          ...entry,
+          sourceCreatedAt: parseKoreaderSourceCreatedAt(entry.dt, timeZone),
+        })),
      });
    }

@@ -427,9 +445,10 @@ export class KoreaderAnnotationExchangeService {
    return candidate;
  }

-  private toIncoming(change: KoreaderAnnotationDto): IncomingDeviceAnnotation {
+  private toIncoming(change: KoreaderAnnotationDto, timeZone: string): IncomingDeviceAnnotation {
    return {
      datetime: change.datetime,
+      sourceCreatedAt: parseKoreaderSourceCreatedAt(change.datetime, timeZone),
      datetimeUpdated: change.datetimeUpdated ?? null,
      drawer: change.drawer,
      color: change.color ?? null,