feat: implement reading session tracking for epub, pdf, and cbz readers

client/src/features/reader/ReaderView.vue

@@ -3,6 +3,7 @@ import { nextTick, onMounted, onUnmounted, ref } from 'vue'
 import { useRoute, useRouter } from 'vue-router'
 import { useFoliate, type RelocateDetail } from './epub/composables/useFoliate'
 import { useReaderProgress } from './shared/composables/useReaderProgress'
+import { useReadingSession } from './shared/composables/useReadingSession'
 import { useReaderState } from './epub/composables/useReaderState'
 import { useReaderSettings } from './shared/composables/useReaderSettings'
 import { useVisibility } from './shared/composables/useVisibility'
@@ -66,6 +67,12 @@ const {
 const progress = useReaderProgress(bookId, fileId)
 const { cfi, chapterTitle, sectionIndex, totalSections, fraction, updateHeadsFeet } = progress
 
+const { onActivity } = useReadingSession(fileId, () => ({
+  percentage: progress.percentage.value,
+  cfi: progress.cfi.value,
+  pageNumber: progress.pageNumber.value,
+}))
+
 const visibility = useVisibility()
 const { headerVisible, footerVisible, handleMiddleTap, showHeader, showFooter } = visibility
 
@@ -82,6 +89,7 @@ const selection = useReaderSelection()
 
 function onRelocateHandler(detail: RelocateDetail) {
   progress.onRelocate(detail)
+  onActivity()
   bookmarks.setCfi(detail?.cfi ?? null)
   toc.setActiveHref(detail?.tocItem?.href ?? '')
   const renderer = getRenderer()

client/src/features/reader/cbz/CbzReaderView.vue

@@ -4,6 +4,7 @@ import { useRouter } from 'vue-router'
 import { ArrowLeft, ChevronLeft, ChevronRight, ChevronsLeft, ChevronsRight, Settings } from 'lucide-vue-next'
 import { useVisibility } from '../shared/composables/useVisibility'
 import { useReaderProgress } from '../shared/composables/useReaderProgress'
+import { useReadingSession } from '../shared/composables/useReadingSession'
 import { useCbz } from './composables/useCbz'
 import { useCbzSettings } from './composables/useCbzSettings'
 import { useReaderSettings } from '../shared/composables/useReaderSettings'
@@ -16,6 +17,11 @@ const router = useRouter()
 
 const progress = useReaderProgress(props.bookId, props.fileId)
 const { headerVisible, footerVisible, handleMiddleTap, showHeader, showFooter } = useVisibility()
+
+const { onActivity } = useReadingSession(props.fileId, () => ({
+  percentage: progress.percentage.value,
+  pageNumber: progress.pageNumber.value,
+}))
 const { pageCount, bookTitle, loading, error, pageUrl, load } = useCbz(props.fileId, props.bookId)
 const { fitMode, viewMode, scrollMode, direction, bgColor, bgValue, isTwoPage, imgFitClass } = useCbzSettings()
 const bookSettings = useReaderSettings(props.fileId, 'cbz')
@@ -198,6 +204,7 @@ let saveTimer: ReturnType<typeof setTimeout> | null = null
 
 watch(currentPage, (page) => {
   schedulePreload(page)
+  onActivity()
   if (saveTimer) clearTimeout(saveTimer)
   saveTimer = setTimeout(() => {
     progress.pageNumber.value = page + 1

client/src/features/reader/pdf/PdfReaderView.vue

@@ -9,6 +9,7 @@ import { usePdfRenderer } from './composables/usePdfRenderer'
 import { usePdfFind } from './composables/usePdfFind'
 import { usePdfOutline } from './composables/usePdfOutline'
 import { useReaderProgress } from '../shared/composables/useReaderProgress'
+import { useReadingSession } from '../shared/composables/useReadingSession'
 import { useReaderSettings } from '../shared/composables/useReaderSettings'
 import PdfToolbar from './components/PdfToolbar.vue'
 import PdfFindBar from './components/FindBar.vue'
@@ -23,6 +24,11 @@ const { pdfDoc, totalPages, loading, error, load, getPageDim, startRenderPage, g
 const progress = useReaderProgress(props.bookId, props.fileId)
 const bookSettings = useReaderSettings(props.fileId, 'pdf')
 
+const { onActivity } = useReadingSession(props.fileId, () => ({
+  percentage: progress.percentage.value,
+  pageNumber: progress.pageNumber.value,
+}))
+
 // ── Layout container ──────────────────────────────────────────────────────────
 const scrollRef = ref<HTMLElement | null>(null)
 const containerW = ref(0)
@@ -137,6 +143,7 @@ watch([spread, scrollMode], async () => {
 let saveTimer: ReturnType<typeof setTimeout> | null = null
 
 watch(currentPage, (page) => {
+  onActivity()
   if (saveTimer) clearTimeout(saveTimer)
   saveTimer = setTimeout(() => {
     progress.pageNumber.value = page

client/src/features/reader/shared/composables/useReaderProgress.ts

@@ -1,4 +1,4 @@
-import { ref } from 'vue'
+import { onUnmounted, ref } from 'vue'
 import { api } from '@/lib/api'
 import type { FoliateRenderer, RelocateDetail } from '../../epub/composables/useFoliate'
 
@@ -10,13 +10,12 @@ export function useReaderProgress(bookId: number, fileId: number) {
   const sectionIndex = ref(0)
   const totalSections = ref(0)
   const fraction = ref(0)
-  const sessionId =
-    typeof crypto !== 'undefined' && typeof crypto.randomUUID === 'function'
-      ? crypto.randomUUID()
-      : `session-${Date.now()}-${Math.random().toString(36).slice(2, 10)}`
 
   let saveTimer: ReturnType<typeof setTimeout> | null = null
-  let eventSequence = 0
+
+  onUnmounted(() => {
+    if (saveTimer) clearTimeout(saveTimer)
+  })
 
   async function load() {
     const res = await api(`/api/v1/books/files/${fileId}/progress`)
@@ -40,7 +39,6 @@ export function useReaderProgress(bookId: number, fileId: number) {
   }
 
   async function save() {
-    eventSequence += 1
     await api(`/api/v1/books/files/${fileId}/progress`, {
       method: 'POST',
       headers: { 'Content-Type': 'application/json' },
@@ -48,8 +46,6 @@ export function useReaderProgress(bookId: number, fileId: number) {
         cfi: cfi.value,
         pageNumber: pageNumber.value,
         percentage: percentage.value,
-        eventKey: `${sessionId}:${eventSequence}`,
-        source: 'reader-web',
       }),
     })
   }

client/src/features/reader/shared/composables/useReadingSession.ts

@@ -0,0 +1,132 @@
+import { onUnmounted } from 'vue'
+import { api } from '@/lib/api'
+
+export interface ProgressSnapshot {
+  percentage: number
+  cfi?: string | null
+  pageNumber?: number | null
+}
+
+const IDLE_TIMEOUT_MS = 5 * 60 * 1000
+const MIN_SESSION_MS = 10 * 1000
+
+function generateSessionId(): string {
+  return typeof crypto !== 'undefined' && typeof crypto.randomUUID === 'function'
+    ? crypto.randomUUID()
+    : `session-${Date.now()}-${Math.random().toString(36).slice(2, 10)}`
+}
+
+export function useReadingSession(bookFileId: number, getProgress: () => ProgressSnapshot) {
+  let sessionId = generateSessionId()
+  let startedAt: Date | null = null
+  let activeMs = 0
+  let activeStart: number | null = null
+  let idleTimer: ReturnType<typeof setTimeout> | null = null
+  let startProgress: number | null = null
+  let ended = false
+
+  function startSession() {
+    startedAt = new Date()
+    activeStart = Date.now()
+    activeMs = 0
+    ended = false
+    startProgress = getProgress().percentage
+    resetIdleTimer()
+  }
+
+  function pauseTimer() {
+    if (activeStart !== null) {
+      activeMs += Date.now() - activeStart
+      activeStart = null
+    }
+    clearIdleTimer()
+  }
+
+  function resumeTimer() {
+    if (activeStart !== null) return
+    activeStart = Date.now()
+    resetIdleTimer()
+  }
+
+  function resetIdleTimer() {
+    clearIdleTimer()
+    idleTimer = setTimeout(endSession, IDLE_TIMEOUT_MS)
+  }
+
+  function clearIdleTimer() {
+    if (idleTimer !== null) {
+      clearTimeout(idleTimer)
+      idleTimer = null
+    }
+  }
+
+  function onActivity() {
+    // No active session or previous session ended (e.g. after idle timeout) — start fresh.
+    if (!startedAt || ended) {
+      sessionId = generateSessionId()
+      startSession()
+      return
+    }
+    if (activeStart === null) resumeTimer()
+    resetIdleTimer()
+  }
+
+  function endSession(useBeacon = false) {
+    if (ended || !startedAt) return
+    ended = true
+    clearIdleTimer()
+
+    if (activeStart !== null) {
+      activeMs += Date.now() - activeStart
+      activeStart = null
+    }
+
+    if (activeMs < MIN_SESSION_MS) return
+
+    const endedAt = new Date()
+    const snap = getProgress()
+    const durationSeconds = Math.floor(activeMs / 1000)
+    const progressDelta = startProgress !== null ? Number((snap.percentage - startProgress).toFixed(4)) : null
+    const endProgress = snap.percentage
+
+    const payload = JSON.stringify({
+      sessionId,
+      startedAt: startedAt.toISOString(),
+      endedAt: endedAt.toISOString(),
+      durationSeconds,
+      progressDelta,
+      endProgress,
+    })
+
+    const url = `/api/v1/books/files/${bookFileId}/sessions`
+
+    if (useBeacon && typeof navigator.sendBeacon === 'function') {
+      navigator.sendBeacon(url, new Blob([payload], { type: 'application/json' }))
+    } else {
+      api(url, { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: payload }).catch(() => {})
+    }
+  }
+
+  function onVisibilityChange() {
+    if (document.visibilityState === 'hidden') {
+      pauseTimer()
+    } else if (startedAt && !ended) {
+      resumeTimer()
+    }
+  }
+
+  function onBeforeUnload() {
+    endSession(true)
+  }
+
+  document.addEventListener('visibilitychange', onVisibilityChange)
+  window.addEventListener('beforeunload', onBeforeUnload)
+
+  onUnmounted(() => {
+    endSession()
+    document.removeEventListener('visibilitychange', onVisibilityChange)
+    window.removeEventListener('beforeunload', onBeforeUnload)
+  })
+
+  return { onActivity, endSession }
+}

client/typecheck-baseline.txt

@@ -24,9 +24,9 @@ src/features/reader/pdf/composables/usePdfRenderer.ts(97,17): error TS18048: 'e'
 src/features/reader/pdf/composables/usePdfRenderer.ts(98,34): error TS18048: 'f' is possibly 'undefined'.
 src/features/reader/pdf/composables/usePdfRenderer.ts(99,31): error TS18048: 'a' is possibly 'undefined'.
 src/features/reader/pdf/composables/usePdfRenderer.ts(99,50): error TS18048: 'b' is possibly 'undefined'.
-src/features/reader/ReaderView.vue(149,15): error TS2345: Argument of type 'unknown[]' is not assignable to parameter of type 'RawTocItem[]'.
-src/features/reader/ReaderView.vue(241,12): error TS2345: Argument of type '{}' is not assignable to parameter of type 'FoliateView'.
-src/features/reader/ReaderView.vue(253,15): error TS2345: Argument of type 'unknown' is not assignable to parameter of type 'FoliateView | null'.
+src/features/reader/ReaderView.vue(157,15): error TS2345: Argument of type 'unknown[]' is not assignable to parameter of type 'RawTocItem[]'.
+src/features/reader/ReaderView.vue(249,12): error TS2345: Argument of type '{}' is not assignable to parameter of type 'FoliateView'.
+src/features/reader/ReaderView.vue(261,15): error TS2345: Argument of type 'unknown' is not assignable to parameter of type 'FoliateView | null'.
 src/features/settings/metadata-preferences/components/FieldConfigSheet.vue(57,25): error TS2322: Type 'MetadataProviderKey | undefined' is not assignable to type 'MetadataProviderKey'.
 src/features/settings/metadata-preferences/components/FieldConfigSheet.vue(57,5): error TS2322: Type 'MetadataProviderKey | undefined' is not assignable to type 'MetadataProviderKey'.
 src/features/settings/metadata-preferences/components/FieldConfigSheet.vue(65,21): error TS2322: Type 'MetadataProviderKey | undefined' is not assignable to type 'MetadataProviderKey'.

scripts/seed/reading-sessions.sh

@@ -0,0 +1,140 @@
+#!/usr/bin/env bash
+# Seeds synthetic reading sessions and daily stats for the first user so that
+# all user-statistics charts (heatmap, peak hours, completion timeline, etc.)
+# show realistic data out of the box.
+#
+# Safe to run multiple times - sessions are deduplicated by session_id and
+# daily stats are upserted. Running again adds more data on top.
+#
+# Usage: ./scripts/seed/reading-sessions.sh [USER_ID]
+#   USER_ID defaults to 1.
+
+set -euo pipefail
+
+ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
+cd "$ROOT_DIR"
+
+POSTGRES_USER="${POSTGRES_USER:-projectx}"
+POSTGRES_DB="${POSTGRES_DB:-projectx}"
+TARGET_USER_ID="${1:-1}"
+
+echo "Seeding reading sessions for user_id=${TARGET_USER_ID}..."
+
+docker compose exec -T postgres psql -U "$POSTGRES_USER" -d "$POSTGRES_DB" << EOSQL
+
+DO \$\$
+DECLARE
+  v_user_id    int := ${TARGET_USER_ID};
+  v_day        date;
+  v_file_id    int;
+  v_library_id int;
+  v_sessions   int;
+  v_i          int;
+  v_hour       int;
+  v_duration   int;
+  v_started    timestamptz;
+  v_ended      timestamptz;
+  v_end_pct    real;
+  v_delta      real;
+  v_session_id text;
+  v_dow        int;
+  v_file_ids   int[];
+  v_total_sessions int := 0;
+  v_total_completions int := 0;
+BEGIN
+  -- Verify user exists
+  IF NOT EXISTS (SELECT 1 FROM users WHERE id = v_user_id) THEN
+    RAISE EXCEPTION 'User with id % not found', v_user_id;
+  END IF;
+
+  -- Verify there are book files to work with
+  IF NOT EXISTS (SELECT 1 FROM book_files LIMIT 1) THEN
+    RAISE EXCEPTION 'No book files found - scan a library first';
+  END IF;
+
+  -- Pick up to 40 real file ids to spread sessions across
+  SELECT array_agg(id ORDER BY random()) INTO v_file_ids
+  FROM (SELECT id FROM book_files ORDER BY random() LIMIT 40) t;
+
+  -- Spread books.added_at across the past 3 years so Format Share Over Time
+  -- chart has data across multiple months instead of a single spike today.
+  UPDATE books SET added_at = now() - (random() * interval '3 years')
+  WHERE added_at > now() - interval '7 days';
+
+  -- Insert sessions across the past 365 days
+  FOR v_day IN
+    SELECT generate_series(
+      current_date - interval '364 days',
+      current_date,
+      interval '1 day'
+    )::date
+  LOOP
+    v_dow := extract(dow from v_day); -- 0=Sun 6=Sat
+
+    -- Weekends: 1-3 sessions. Weekdays: 0-2 (30% chance of 0).
+    IF v_dow IN (0, 6) THEN
+      v_sessions := 1 + floor(random() * 3)::int;
+    ELSIF random() < 0.30 THEN
+      v_sessions := 0;
+    ELSE
+      v_sessions := 1 + floor(random() * 2)::int;
+    END IF;
+
+    FOR v_i IN 1..v_sessions LOOP
+      v_file_id := v_file_ids[1 + floor(random() * array_length(v_file_ids, 1))::int];
+
+      SELECT b.library_id INTO v_library_id
+      FROM book_files bf JOIN books b ON b.id = bf.book_id
+      WHERE bf.id = v_file_id;
+
+      -- Realistic hour distribution: mostly evenings, some mornings/afternoons
+      IF random() < 0.60 THEN
+        v_hour := 18 + floor(random() * 6)::int;  -- 18-23 evening
+      ELSIF random() < 0.50 THEN
+        v_hour := 7  + floor(random() * 3)::int;  -- 7-9 morning
+      ELSE
+        v_hour := 12 + floor(random() * 4)::int;  -- 12-15 afternoon
+      END IF;
+
+      v_started  := (v_day + make_interval(hours => v_hour, mins => floor(random() * 60)::int))::timestamptz;
+      v_duration := 600 + floor(random() * 3000)::int;   -- 10-60 min
+      v_ended    := v_started + make_interval(secs => v_duration);
+      v_delta    := round((1 + random() * 8)::numeric, 4); -- 1-9% progress
+      -- ~15% of sessions are completions (every 7th deterministically by loop)
+      IF (v_total_sessions % 7) = 0 THEN
+        v_end_pct := 100;
+        v_total_completions := v_total_completions + 1;
+      ELSE
+        v_end_pct := round((10 + random() * 80)::numeric, 2);
+      END IF;
+
+      v_session_id := md5(v_user_id::text || v_file_id::text || v_started::text || v_i::text);
+
+      INSERT INTO reading_sessions
+        (user_id, book_file_id, session_id, started_at, ended_at, duration_seconds, progress_delta, end_progress)
+      VALUES
+        (v_user_id, v_file_id, v_session_id, v_started, v_ended, v_duration, v_delta, v_end_pct)
+      ON CONFLICT (session_id) DO NOTHING;
+
+      -- Real-time upsert of daily stats (mirrors what the server does on session save)
+      INSERT INTO user_reading_daily_stats
+        (user_id, library_id, day, reading_seconds, progress_delta, sessions_count, updated_at)
+      VALUES
+        (v_user_id, v_library_id, v_day, v_duration, v_delta, 1, now())
+      ON CONFLICT (user_id, library_id, day) DO UPDATE SET
+        reading_seconds = user_reading_daily_stats.reading_seconds + excluded.reading_seconds,
+        progress_delta  = user_reading_daily_stats.progress_delta  + excluded.progress_delta,
+        sessions_count  = user_reading_daily_stats.sessions_count  + 1,
+        updated_at      = now();
+
+      v_total_sessions := v_total_sessions + 1;
+    END LOOP;
+  END LOOP;
+
+  RAISE NOTICE 'Done: % sessions inserted (% completions)', v_total_sessions, v_total_completions;
+END;
+\$\$;
+
+EOSQL
+
+echo "Reading session seed complete."

server/package.json

@@ -18,6 +18,7 @@
     "db:migrate": "drizzle-kit migrate",
     "db:migrate:runtime": "node dist/scripts/migrate.js",
     "db:studio": "drizzle-kit studio",
+    "db:seed": "tsx src/scripts/db-seed.ts",
     "pretype-check": "pnpm --filter @projectx/types build",
     "type-check": "tsc --noEmit -p tsconfig.build.json",
     "lint": "pnpm run lint:check",

server/src/app.module.ts

@@ -47,6 +47,7 @@ import { BookMetadataFetchModule } from './modules/book-metadata-fetch/book-meta
 import { MetadataScoreModule } from './modules/metadata-score/metadata-score.module';
 import { StatisticsModule } from './modules/statistics/statistics.module';
 import { UserStatisticsModule } from './modules/user-statistics/user-statistics.module';
+import { ReadingSessionModule } from './modules/reading-session/reading-session.module';
 import { AuditModule } from './modules/audit/audit.module';
 
 @Module({
@@ -94,6 +95,7 @@ import { AuditModule } from './modules/audit/audit.module';
     MetadataScoreModule,
     StatisticsModule,
     UserStatisticsModule,
+    ReadingSessionModule,
     AuditModule,
   ],
   providers: [

server/src/db/migrations/0000_baseline.sql

@@ -1,5 +1,3 @@
-CREATE EXTENSION IF NOT EXISTS vector;--> statement-breakpoint
-CREATE EXTENSION IF NOT EXISTS pg_trgm;--> statement-breakpoint
 CREATE TYPE "public"."library_access_level" AS ENUM('viewer', 'editor', 'owner');--> statement-breakpoint
 CREATE TYPE "public"."opds_sort_order" AS ENUM('recent', 'title_asc', 'title_desc', 'author_asc', 'author_desc', 'series_asc', 'series_desc');--> statement-breakpoint
 CREATE TABLE "audit_log" (
@@ -325,20 +323,16 @@ CREATE TABLE "reading_progress" (
 	CONSTRAINT "reading_progress_book_file_id_user_id_pk" PRIMARY KEY("book_file_id","user_id")
 );
 --> statement-breakpoint
-CREATE TABLE "reading_session_events" (
+CREATE TABLE "reading_sessions" (
 	"id" serial PRIMARY KEY NOT NULL,
 	"user_id" integer NOT NULL,
 	"book_file_id" integer NOT NULL,
-	"event_key" varchar(120) NOT NULL,
-	"recorded_at" timestamp DEFAULT now() NOT NULL,
-	"percentage" real NOT NULL,
-	"percentage_delta" real DEFAULT 0 NOT NULL,
-	"page_number" integer,
-	"page_delta" integer DEFAULT 0 NOT NULL,
-	"delta_seconds" integer DEFAULT 0 NOT NULL,
-	"source" varchar(40) DEFAULT 'reader' NOT NULL,
-	"synthetic" boolean DEFAULT false NOT NULL,
-	"created_at" timestamp DEFAULT now() NOT NULL
+	"session_id" varchar(64) NOT NULL,
+	"started_at" timestamp NOT NULL,
+	"ended_at" timestamp NOT NULL,
+	"duration_seconds" integer NOT NULL,
+	"progress_delta" real,
+	"end_progress" real
 );
 --> statement-breakpoint
 CREATE TABLE "user_reading_daily_stats" (
@@ -347,7 +341,7 @@ CREATE TABLE "user_reading_daily_stats" (
 	"day" date NOT NULL,
 	"reading_seconds" integer DEFAULT 0 NOT NULL,
 	"progress_delta" real DEFAULT 0 NOT NULL,
-	"events_count" integer DEFAULT 0 NOT NULL,
+	"sessions_count" integer DEFAULT 0 NOT NULL,
 	"updated_at" timestamp DEFAULT now() NOT NULL,
 	CONSTRAINT "user_reading_daily_stats_user_id_library_id_day_pk" PRIMARY KEY("user_id","library_id","day")
 );
@@ -605,8 +599,8 @@ ALTER TABLE "reader_preferences" ADD CONSTRAINT "reader_preferences_user_id_user
 ALTER TABLE "reader_preferences" ADD CONSTRAINT "reader_preferences_book_file_id_book_files_id_fk" FOREIGN KEY ("book_file_id") REFERENCES "public"."book_files"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
 ALTER TABLE "reading_progress" ADD CONSTRAINT "reading_progress_book_file_id_book_files_id_fk" FOREIGN KEY ("book_file_id") REFERENCES "public"."book_files"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
 ALTER TABLE "reading_progress" ADD CONSTRAINT "reading_progress_user_id_users_id_fk" FOREIGN KEY ("user_id") REFERENCES "public"."users"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
-ALTER TABLE "reading_session_events" ADD CONSTRAINT "reading_session_events_user_id_users_id_fk" FOREIGN KEY ("user_id") REFERENCES "public"."users"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
-ALTER TABLE "reading_session_events" ADD CONSTRAINT "reading_session_events_book_file_id_book_files_id_fk" FOREIGN KEY ("book_file_id") REFERENCES "public"."book_files"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+ALTER TABLE "reading_sessions" ADD CONSTRAINT "reading_sessions_user_id_users_id_fk" FOREIGN KEY ("user_id") REFERENCES "public"."users"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+ALTER TABLE "reading_sessions" ADD CONSTRAINT "reading_sessions_book_file_id_book_files_id_fk" FOREIGN KEY ("book_file_id") REFERENCES "public"."book_files"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
 ALTER TABLE "user_reading_daily_stats" ADD CONSTRAINT "user_reading_daily_stats_user_id_users_id_fk" FOREIGN KEY ("user_id") REFERENCES "public"."users"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
 ALTER TABLE "user_reading_daily_stats" ADD CONSTRAINT "user_reading_daily_stats_library_id_libraries_id_fk" FOREIGN KEY ("library_id") REFERENCES "public"."libraries"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
 ALTER TABLE "oidc_sessions" ADD CONSTRAINT "oidc_sessions_user_id_users_id_fk" FOREIGN KEY ("user_id") REFERENCES "public"."users"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
@@ -664,9 +658,10 @@ CREATE INDEX "bookmarks_user_id_idx" ON "bookmarks" USING btree ("user_id");-->
 CREATE UNIQUE INDEX "rdp_user_format_idx" ON "reader_default_preferences" USING btree ("user_id","format_group");--> statement-breakpoint
 CREATE UNIQUE INDEX "rp_user_file_idx" ON "reader_preferences" USING btree ("user_id","book_file_id");--> statement-breakpoint
 CREATE INDEX "reading_progress_user_id_idx" ON "reading_progress" USING btree ("user_id");--> statement-breakpoint
-CREATE UNIQUE INDEX "rse_event_key_uidx" ON "reading_session_events" USING btree ("event_key");--> statement-breakpoint
-CREATE INDEX "rse_user_recorded_at_idx" ON "reading_session_events" USING btree ("user_id","recorded_at");--> statement-breakpoint
-CREATE INDEX "rse_file_recorded_at_idx" ON "reading_session_events" USING btree ("book_file_id","recorded_at");--> statement-breakpoint
+CREATE UNIQUE INDEX "rs_session_id_uidx" ON "reading_sessions" USING btree ("session_id");--> statement-breakpoint
+CREATE INDEX "rs_user_started_at_idx" ON "reading_sessions" USING btree ("user_id","started_at");--> statement-breakpoint
+CREATE INDEX "rs_book_file_started_at_idx" ON "reading_sessions" USING btree ("book_file_id","started_at");--> statement-breakpoint
+CREATE INDEX "rs_user_book_file_idx" ON "reading_sessions" USING btree ("user_id","book_file_id");--> statement-breakpoint
 CREATE INDEX "urds_user_day_idx" ON "user_reading_daily_stats" USING btree ("user_id","day");--> statement-breakpoint
 CREATE INDEX "urds_user_library_day_idx" ON "user_reading_daily_stats" USING btree ("user_id","library_id","day");--> statement-breakpoint
 CREATE INDEX "oidc_sessions_user_id_idx" ON "oidc_sessions" USING btree ("user_id");--> statement-breakpoint

server/src/db/migrations/meta/0000_snapshot.json

@@ -1,5 +1,5 @@
 {
-  "id": "bcba426a-a81b-4b4b-a3a1-e3f2e14c3819",
+  "id": "527f8ce7-3ed2-4f6d-aa0d-4fd227a23118",
   "prevId": "00000000-0000-0000-0000-000000000000",
   "version": "7",
   "dialect": "postgresql",
@@ -2597,8 +2597,8 @@
       "checkConstraints": {},
       "isRLSEnabled": false
     },
-    "public.reading_session_events": {
-      "name": "reading_session_events",
+    "public.reading_sessions": {
+      "name": "reading_sessions",
       "schema": "",
       "columns": {
         "id": {
@@ -2619,80 +2619,49 @@
           "primaryKey": false,
           "notNull": true
         },
-        "event_key": {
-          "name": "event_key",
-          "type": "varchar(120)",
+        "session_id": {
+          "name": "session_id",
+          "type": "varchar(64)",
           "primaryKey": false,
           "notNull": true
         },
-        "recorded_at": {
-          "name": "recorded_at",
+        "started_at": {
+          "name": "started_at",
           "type": "timestamp",
           "primaryKey": false,
-          "notNull": true,
-          "default": "now()"
+          "notNull": true
         },
-        "percentage": {
-          "name": "percentage",
-          "type": "real",
+        "ended_at": {
+          "name": "ended_at",
+          "type": "timestamp",
           "primaryKey": false,
           "notNull": true
         },
-        "percentage_delta": {
-          "name": "percentage_delta",
-          "type": "real",
-          "primaryKey": false,
-          "notNull": true,
-          "default": 0
-        },
-        "page_number": {
-          "name": "page_number",
+        "duration_seconds": {
+          "name": "duration_seconds",
           "type": "integer",
           "primaryKey": false,
+          "notNull": true
+        },
+        "progress_delta": {
+          "name": "progress_delta",
+          "type": "real",
+          "primaryKey": false,
           "notNull": false
         },
-        "page_delta": {
-          "name": "page_delta",
-          "type": "integer",
+        "end_progress": {
+          "name": "end_progress",
+          "type": "real",
           "primaryKey": false,
-          "notNull": true,
-          "default": 0
-        },
-        "delta_seconds": {
-          "name": "delta_seconds",
-          "type": "integer",
-          "primaryKey": false,
-          "notNull": true,
-          "default": 0
-        },
-        "source": {
-          "name": "source",
-          "type": "varchar(40)",
-          "primaryKey": false,
-          "notNull": true,
-          "default": "'reader'"
-        },
-        "synthetic": {
-          "name": "synthetic",
-          "type": "boolean",
-          "primaryKey": false,
-          "notNull": true,
-          "default": false
-        },
-        "created_at": {
-          "name": "created_at",
-          "type": "timestamp",
-          "primaryKey": false,
-          "notNull": true,
-          "default": "now()"
+          "notNull": false
         }
       },
       "indexes": {
-        "rse_event_key_uidx": {
-          "name": "rse_event_key_uidx",
+        "rs_session_id_uidx": {
+          "name": "rs_session_id_uidx",
           "columns": [
             {
-              "expression": "event_key",
+              "expression": "session_id",
               "isExpression": false,
               "asc": true,
               "nulls": "last"
@@ -2703,8 +2672,8 @@
           "method": "btree",
           "with": {}
         },
-        "rse_user_recorded_at_idx": {
-          "name": "rse_user_recorded_at_idx",
+        "rs_user_started_at_idx": {
+          "name": "rs_user_started_at_idx",
           "columns": [
             {
               "expression": "user_id",
@@ -2713,7 +2682,7 @@
               "nulls": "last"
             },
             {
-              "expression": "recorded_at",
+              "expression": "started_at",
               "isExpression": false,
               "asc": true,
               "nulls": "last"
@@ -2724,8 +2693,8 @@
           "method": "btree",
           "with": {}
         },
-        "rse_file_recorded_at_idx": {
-          "name": "rse_file_recorded_at_idx",
+        "rs_book_file_started_at_idx": {
+          "name": "rs_book_file_started_at_idx",
           "columns": [
             {
               "expression": "book_file_id",
@@ -2734,7 +2703,28 @@
               "nulls": "last"
             },
             {
-              "expression": "recorded_at",
+              "expression": "started_at",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            }
+          ],
+          "isUnique": false,
+          "concurrently": false,
+          "method": "btree",
+          "with": {}
+        },
+        "rs_user_book_file_idx": {
+          "name": "rs_user_book_file_idx",
+          "columns": [
+            {
+              "expression": "user_id",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            },
+            {
+              "expression": "book_file_id",
               "isExpression": false,
               "asc": true,
               "nulls": "last"
@@ -2747,18 +2737,18 @@
         }
       },
       "foreignKeys": {
-        "reading_session_events_user_id_users_id_fk": {
-          "name": "reading_session_events_user_id_users_id_fk",
-          "tableFrom": "reading_session_events",
+        "reading_sessions_user_id_users_id_fk": {
+          "name": "reading_sessions_user_id_users_id_fk",
+          "tableFrom": "reading_sessions",
           "tableTo": "users",
           "columnsFrom": ["user_id"],
           "columnsTo": ["id"],
           "onDelete": "cascade",
           "onUpdate": "no action"
         },
-        "reading_session_events_book_file_id_book_files_id_fk": {
-          "name": "reading_session_events_book_file_id_book_files_id_fk",
-          "tableFrom": "reading_session_events",
+        "reading_sessions_book_file_id_book_files_id_fk": {
+          "name": "reading_sessions_book_file_id_book_files_id_fk",
+          "tableFrom": "reading_sessions",
           "tableTo": "book_files",
           "columnsFrom": ["book_file_id"],
           "columnsTo": ["id"],
@@ -2808,8 +2798,8 @@
           "notNull": true,
           "default": 0
         },
-        "events_count": {
-          "name": "events_count",
+        "sessions_count": {
+          "name": "sessions_count",
           "type": "integer",
           "primaryKey": false,
           "notNull": true,

server/src/db/migrations/meta/_journal.json

@@ -5,7 +5,7 @@
     {
       "idx": 0,
       "version": "7",
-      "when": 1773989484660,
+      "when": 1774017368689,
       "tag": "0000_baseline",
       "breakpoints": true
     }

server/src/db/schema/reader.test.ts

@@ -6,7 +6,7 @@ import {
   readerDefaultPreferences,
   readerPreferences,
   readingProgress,
-  readingSessionEvents,
+  readingSessions,
   userReadingDailyStats,
 } from './reader';
 
@@ -35,19 +35,18 @@ describe('reader schema', () => {
     expect(readingProgress.updatedAt.onUpdateFn?.()).toBeInstanceOf(Date);
   });
 
-  it('stores append-only reading session events with idempotency and time indexes', () => {
-    const config = getTableConfig(readingSessionEvents);
+  it('stores reading sessions with idempotency and time indexes', () => {
+    const config = getTableConfig(readingSessions);
     const uniqueIndexes = config.indexes.filter((idx) => idx.config.unique);
     const indexNames = config.indexes.map((idx) => idx.config.name);
-    const fkMap = fkByColumn(readingSessionEvents);
+    const fkMap = fkByColumn(readingSessions);
 
-    expect(uniqueIndexes.some((idx) => idx.config.name === 'rse_event_key_uidx')).toBe(true);
-    expect(indexNames).toContain('rse_user_recorded_at_idx');
-    expect(indexNames).toContain('rse_file_recorded_at_idx');
+    expect(uniqueIndexes.some((idx) => idx.config.name === 'rs_session_id_uidx')).toBe(true);
+    expect(indexNames).toContain('rs_user_started_at_idx');
+    expect(indexNames).toContain('rs_book_file_started_at_idx');
+    expect(indexNames).toContain('rs_user_book_file_idx');
     expect(fkMap.get('user_id')?.onDelete).toBe('cascade');
     expect(fkMap.get('book_file_id')?.onDelete).toBe('cascade');
-    expect(readingSessionEvents.source.default).toBe('reader');
-    expect(readingSessionEvents.synthetic.default).toBe(false);
   });
 
   it('stores user daily reading aggregates keyed by user, library, and day', () => {

server/src/db/schema/reader.ts

@@ -1,4 +1,4 @@
-import { boolean, date, index, integer, jsonb, pgTable, primaryKey, real, serial, text, timestamp, uniqueIndex, varchar } from 'drizzle-orm/pg-core';
+import { date, index, integer, jsonb, pgTable, primaryKey, real, serial, text, timestamp, uniqueIndex, varchar } from 'drizzle-orm/pg-core';
 
 import { bookFiles, books } from './books';
 import { libraries } from './libraries';
@@ -29,8 +29,8 @@ export const readingProgress = pgTable(
 export type ReadingProgress = typeof readingProgress.$inferSelect;
 export type NewReadingProgress = typeof readingProgress.$inferInsert;
 
-export const readingSessionEvents = pgTable(
-  'reading_session_events',
+export const readingSessions = pgTable(
+  'reading_sessions',
   {
     id: serial('id').primaryKey(),
     userId: integer('user_id')
@@ -39,27 +39,26 @@ export const readingSessionEvents = pgTable(
     bookFileId: integer('book_file_id')
       .notNull()
       .references(() => bookFiles.id, { onDelete: 'cascade' }),
-    // Idempotency key from the client save call; retries must reuse this value.
-    eventKey: varchar('event_key', { length: 120 }).notNull(),
-    recordedAt: timestamp('recorded_at').notNull().defaultNow(),
-    percentage: real('percentage').notNull(),
-    percentageDelta: real('percentage_delta').notNull().default(0),
-    pageNumber: integer('page_number'),
-    pageDelta: integer('page_delta').notNull().default(0),
-    deltaSeconds: integer('delta_seconds').notNull().default(0),
-    source: varchar('source', { length: 40 }).notNull().default('reader'),
-    synthetic: boolean('synthetic').notNull().default(false),
-    createdAt: timestamp('created_at').notNull().defaultNow(),
+    // Client-generated UUID; used for idempotent retries.
+    sessionId: varchar('session_id', { length: 64 }).notNull(),
+    startedAt: timestamp('started_at').notNull(),
+    endedAt: timestamp('ended_at').notNull(),
+    // Server-computed from endedAt - startedAt; client-provided timestamps are untrusted for duration.
+    durationSeconds: integer('duration_seconds').notNull(),
+    // Nullable: CBX with no percentage tracking may omit these.
+    progressDelta: real('progress_delta'),
+    endProgress: real('end_progress'),
   },
   (t) => [
-    uniqueIndex('rse_event_key_uidx').on(t.eventKey),
-    index('rse_user_recorded_at_idx').on(t.userId, t.recordedAt),
-    index('rse_file_recorded_at_idx').on(t.bookFileId, t.recordedAt),
+    uniqueIndex('rs_session_id_uidx').on(t.sessionId),
+    index('rs_user_started_at_idx').on(t.userId, t.startedAt),
+    index('rs_book_file_started_at_idx').on(t.bookFileId, t.startedAt),
+    index('rs_user_book_file_idx').on(t.userId, t.bookFileId),
   ],
 );
 
-export type ReadingSessionEvent = typeof readingSessionEvents.$inferSelect;
-export type NewReadingSessionEvent = typeof readingSessionEvents.$inferInsert;
+export type ReadingSession = typeof readingSessions.$inferSelect;
+export type NewReadingSession = typeof readingSessions.$inferInsert;
 
 export const userReadingDailyStats = pgTable(
   'user_reading_daily_stats',
@@ -73,7 +72,7 @@ export const userReadingDailyStats = pgTable(
     day: date('day', { mode: 'string' }).notNull(),
     readingSeconds: integer('reading_seconds').notNull().default(0),
     progressDelta: real('progress_delta').notNull().default(0),
-    eventsCount: integer('events_count').notNull().default(0),
+    sessionsCount: integer('sessions_count').notNull().default(0),
     updatedAt: timestamp('updated_at')
       .notNull()
       .defaultNow()

server/src/modules/book/book.repository.test.ts

@@ -195,102 +195,30 @@ describe('BookRepository', () => {
     expect(db.select).not.toHaveBeenCalled();
   });
 
-  it('upserts reading progress and appends an idempotent session event', async () => {
-    vi.useFakeTimers();
-    try {
-      vi.setSystemTime(new Date('2026-01-01T00:00:10.000Z'));
-
-      const selectLimit = vi.fn().mockResolvedValue([{ percentage: 70, pageNumber: 6, updatedAt: new Date('2026-01-01T00:00:05.000Z') }]);
-      const selectWhere = vi.fn().mockReturnValue({ limit: selectLimit });
-      const selectFrom = vi.fn().mockReturnValue({ where: selectWhere });
-      const select = vi.fn().mockReturnValue({ from: selectFrom });
-
-      const onConflictDoUpdate = vi.fn().mockResolvedValue(undefined);
-      const valuesProgress = vi.fn().mockReturnValue({ onConflictDoUpdate });
-
-      const returningEvent = vi.fn().mockResolvedValue([{ id: 1 }]);
-      const onConflictDoNothing = vi.fn().mockReturnValue({ returning: returningEvent });
-      const valuesEvent = vi.fn().mockReturnValue({ onConflictDoNothing });
-
-      const insert = vi.fn().mockReturnValueOnce({ values: valuesEvent }).mockReturnValueOnce({ values: valuesProgress });
-      const execute = vi.fn().mockResolvedValue(undefined);
-
-      const tx = { execute, select, insert };
-      const transaction = vi.fn(async (fn: (trx: typeof tx) => Promise<void>) => fn(tx));
-      const db = { transaction };
-      const repo = new BookRepository(db as never);
-
-      await repo.upsertProgress(5, 9, 'epubcfi(/6/2)', 7, 80, 'session-1:1', 'reader-web');
-
-      expect(transaction).toHaveBeenCalledTimes(1);
-      expect(execute).toHaveBeenCalledTimes(1);
-      expect(insert).toHaveBeenCalledTimes(2);
-      expect(valuesProgress).toHaveBeenCalledWith(
-        expect.objectContaining({
-          userId: 5,
-          bookFileId: 9,
-          cfi: 'epubcfi(/6/2)',
-          pageNumber: 7,
-          percentage: 80,
-        }),
-      );
-      expect(onConflictDoUpdate).toHaveBeenCalledWith(
-        expect.objectContaining({
-          target: expect.any(Array),
-          set: expect.objectContaining({
-            cfi: 'epubcfi(/6/2)',
-            pageNumber: 7,
-            percentage: 80,
-          }),
-        }),
-      );
-      expect(returningEvent).toHaveBeenCalledWith(expect.objectContaining({ id: expect.anything() }));
-      expect(valuesEvent).toHaveBeenCalledWith(
-        expect.objectContaining({
-          userId: 5,
-          bookFileId: 9,
-          eventKey: 'session-1:1',
-          percentage: 80,
-          percentageDelta: 10,
-          pageNumber: 7,
-          pageDelta: 1,
-          deltaSeconds: 5,
-          source: 'reader-web',
-          synthetic: false,
-        }),
-      );
-      expect(onConflictDoNothing).toHaveBeenCalledWith(expect.objectContaining({ target: expect.any(Array) }));
-    } finally {
-      vi.useRealTimers();
-    }
-  });
-
-  it('does not mutate canonical progress when an event key already exists', async () => {
-    const selectLimit = vi.fn().mockResolvedValue([{ percentage: 70, pageNumber: 6, updatedAt: new Date('2026-01-01T00:00:05.000Z') }]);
-    const selectWhere = vi.fn().mockReturnValue({ limit: selectLimit });
-    const selectFrom = vi.fn().mockReturnValue({ where: selectWhere });
-    const select = vi.fn().mockReturnValue({ from: selectFrom });
-
-    const returningEvent = vi.fn().mockResolvedValue([]);
-    const onConflictDoNothing = vi.fn().mockReturnValue({ returning: returningEvent });
-    const valuesEvent = vi.fn().mockReturnValue({ onConflictDoNothing });
-
+  it('upserts reading progress with an idempotent conflict update', async () => {
     const onConflictDoUpdate = vi.fn().mockResolvedValue(undefined);
-    const valuesProgress = vi.fn().mockReturnValue({ onConflictDoUpdate });
-
-    const insert = vi.fn().mockReturnValueOnce({ values: valuesEvent }).mockReturnValueOnce({ values: valuesProgress });
-    const execute = vi.fn().mockResolvedValue(undefined);
-
-    const tx = { execute, select, insert };
-    const transaction = vi.fn(async (fn: (trx: typeof tx) => Promise<void>) => fn(tx));
-    const db = { transaction };
+    const values = vi.fn().mockReturnValue({ onConflictDoUpdate });
+    const insert = vi.fn().mockReturnValue({ values });
+    const db = { insert };
     const repo = new BookRepository(db as never);
 
-    await repo.upsertProgress(5, 9, 'epubcfi(/6/2)', 7, 80, 'session-1:1', 'reader-web');
+    await repo.upsertProgress(5, 9, 'epubcfi(/6/2)', 7, 80);
 
-    expect(execute).toHaveBeenCalledTimes(1);
-    expect(valuesEvent).toHaveBeenCalledTimes(1);
-    expect(valuesProgress).not.toHaveBeenCalled();
-    expect(onConflictDoUpdate).not.toHaveBeenCalled();
+    expect(insert).toHaveBeenCalledTimes(1);
+    expect(values).toHaveBeenCalledWith(
+      expect.objectContaining({
+        userId: 5,
+        bookFileId: 9,
+        cfi: 'epubcfi(/6/2)',
+        pageNumber: 7,
+        percentage: 80,
+      }),
+    );
+    expect(onConflictDoUpdate).toHaveBeenCalledWith(
+      expect.objectContaining({
+        target: expect.any(Array),
+        set: expect.objectContaining({ cfi: 'epubcfi(/6/2)', pageNumber: 7, percentage: 80 }),
+      }),
+    );
   });
 });

server/src/modules/book/book.repository.ts

@@ -1,6 +1,5 @@
 import { Inject, Injectable } from '@nestjs/common';
 import { SQL, and, count, eq, inArray, isNotNull, or, sql } from 'drizzle-orm';
-import { randomUUID } from 'crypto';
 import { SUPPORTED_BOOK_FORMATS } from '../upload/upload-validator.service';
 import { NodePgDatabase } from 'drizzle-orm/node-postgres';
 
@@ -21,13 +20,11 @@ import {
   koboReadingStates,
   koboSnapshotBooks,
   libraries,
-  readingSessionEvents,
   readingProgress,
   tags,
 } from '../../db/schema';
 
 type Db = NodePgDatabase<typeof schema>;
-const MAX_ACTIVE_GAP_SECONDS = 30 * 60;
 type PatternMetadataRow = {
   bookId: number;
   title: string | null;
@@ -384,70 +381,14 @@ export class BookRepository {
     await this.db.update(bookMetadata).set(fields).where(eq(bookMetadata.bookId, bookId));
   }
 
-  async upsertProgress(
-    userId: number,
-    fileId: number,
-    cfi: string | null,
-    pageNumber: number | null,
-    percentage: number,
-    eventKey: string | null = null,
-    source: string | null = null,
-  ) {
+  async upsertProgress(userId: number, fileId: number, cfi: string | null, pageNumber: number | null, percentage: number) {
     const now = new Date();
-
-    await this.db.transaction(async (tx) => {
-      await tx.execute(sql`select pg_advisory_xact_lock(${userId}, ${fileId})`);
-
-      const [previous] = await tx
-        .select({
-          percentage: readingProgress.percentage,
-          pageNumber: readingProgress.pageNumber,
-          updatedAt: readingProgress.updatedAt,
-        })
-        .from(readingProgress)
-        .where(and(eq(readingProgress.bookFileId, fileId), eq(readingProgress.userId, userId)))
-        .limit(1);
-
-      const previousUpdatedAt = previous?.updatedAt ?? null;
-      const rawGapSeconds = previousUpdatedAt ? Math.floor((now.getTime() - previousUpdatedAt.getTime()) / 1000) : 0;
-      const deltaSeconds = rawGapSeconds > 0 && rawGapSeconds <= MAX_ACTIVE_GAP_SECONDS ? rawGapSeconds : 0;
-
-      const percentageDelta = previous ? Number((percentage - previous.percentage).toFixed(4)) : 0;
-      const pageDelta = previous && pageNumber != null && previous.pageNumber != null ? pageNumber - previous.pageNumber : 0;
-      const effectiveSource = source?.trim() ? source.trim() : 'reader';
-      const normalizedEventKey = eventKey?.trim();
-      const effectiveEventKey = normalizedEventKey ? normalizedEventKey : `srv:${userId}:${fileId}:${now.getTime()}:${randomUUID()}`;
-
-      const insertedEvents = await tx
-        .insert(readingSessionEvents)
-        .values({
-          userId,
-          bookFileId: fileId,
-          eventKey: effectiveEventKey,
-          recordedAt: now,
-          percentage,
-          percentageDelta,
-          pageNumber,
-          pageDelta,
-          deltaSeconds,
-          source: effectiveSource,
-          synthetic: false,
-          createdAt: now,
-        })
-        .onConflictDoNothing({ target: [readingSessionEvents.eventKey] })
-        .returning({ id: readingSessionEvents.id });
-
-      // Client retries must be idempotent: if this event key already exists, do not
-      // mutate canonical progress timestamps or deltas.
-      if (insertedEvents.length === 0) return;
-
-      await tx
-        .insert(readingProgress)
-        .values({ userId, bookFileId: fileId, cfi, pageNumber, percentage, updatedAt: now })
-        .onConflictDoUpdate({
-          target: [readingProgress.bookFileId, readingProgress.userId],
-          set: { cfi, pageNumber, percentage, updatedAt: now },
-        });
-    });
+    await this.db
+      .insert(readingProgress)
+      .values({ userId, bookFileId: fileId, cfi, pageNumber, percentage, updatedAt: now })
+      .onConflictDoUpdate({
+        target: [readingProgress.bookFileId, readingProgress.userId],
+        set: { cfi, pageNumber, percentage, updatedAt: now },
+      });
   }
 }

server/src/modules/book/book.service.ts

@@ -362,15 +362,7 @@ export class BookService {
 
   async saveProgress(userId: number, fileId: number, dto: SaveProgressDto, user: RequestUser) {
     await this.verifyFileAccess(fileId, user);
-    await this.bookRepo.upsertProgress(
-      userId,
-      fileId,
-      dto.cfi ?? null,
-      dto.pageNumber ?? null,
-      dto.percentage,
-      dto.eventKey ?? null,
-      dto.source ?? null,
-    );
+    await this.bookRepo.upsertProgress(userId, fileId, dto.cfi ?? null, dto.pageNumber ?? null, dto.percentage);
   }
 
   async getKoboState(id: number, user: RequestUser): Promise<BookKoboState> {

server/src/modules/book/dto/book-dto-validation.test.ts

@@ -46,25 +46,11 @@ describe('Book DTO validation', () => {
 
   it('validates SaveProgressDto percentage bounds and conditional field types', async () => {
     expect((await errorsFor(SaveProgressDto, { percentage: 0 })).length).toBe(0);
-    expect(
-      (
-        await errorsFor(SaveProgressDto, {
-          percentage: 100,
-          cfi: 'epubcfi(/6/2)',
-          pageNumber: 5,
-          eventKey: 'session-1:9',
-          source: 'reader-web',
-        })
-      ).length,
-    ).toBe(0);
+    expect((await errorsFor(SaveProgressDto, { percentage: 100, cfi: 'epubcfi(/6/2)', pageNumber: 5 })).length).toBe(0);
 
     expect((await errorsFor(SaveProgressDto, { percentage: -1 })).length).toBeGreaterThan(0);
     expect((await errorsFor(SaveProgressDto, { percentage: 50, cfi: 123 })).length).toBeGreaterThan(0);
     expect((await errorsFor(SaveProgressDto, { percentage: 50, pageNumber: 'five' })).length).toBeGreaterThan(0);
-    expect((await errorsFor(SaveProgressDto, { percentage: 50, eventKey: 123 })).length).toBeGreaterThan(0);
-    expect((await errorsFor(SaveProgressDto, { percentage: 50, eventKey: '' })).length).toBeGreaterThan(0);
-    expect((await errorsFor(SaveProgressDto, { percentage: 50, eventKey: '   ' })).length).toBeGreaterThan(0);
-    expect((await errorsFor(SaveProgressDto, { percentage: 50, source: 123 })).length).toBeGreaterThan(0);
   });
 
   it('requires non-empty search text and bounds search limit', async () => {

server/src/modules/book/dto/save-progress.dto.ts

@@ -1,5 +1,4 @@
-import { Transform } from 'class-transformer';
-import { IsInt, IsNumber, IsString, Max, MaxLength, Min, MinLength, ValidateIf } from 'class-validator';
+import { IsNumber, IsString, Max, Min, ValidateIf } from 'class-validator';
 
 export class SaveProgressDto {
   @ValidateIf((o: SaveProgressDto) => o.cfi != null)
@@ -7,24 +6,11 @@ export class SaveProgressDto {
   cfi?: string | null;
 
   @ValidateIf((o: SaveProgressDto) => o.pageNumber != null)
-  @IsInt()
+  @IsNumber()
   pageNumber?: number | null;
 
   @IsNumber()
   @Min(0)
   @Max(100)
   percentage!: number;
-
-  @ValidateIf((o: SaveProgressDto) => o.eventKey != null)
-  @Transform(({ value }) => (typeof value === 'string' ? value.trim() : value))
-  @IsString()
-  @MinLength(1)
-  @MaxLength(120)
-  eventKey?: string | null;
-
-  @ValidateIf((o: SaveProgressDto) => o.source != null)
-  @Transform(({ value }) => (typeof value === 'string' ? value.trim() : value))
-  @IsString()
-  @MaxLength(40)
-  source?: string | null;
 }

server/src/modules/reading-session/dto/save-reading-session.dto.ts

@@ -0,0 +1,31 @@
+import { IsDateString, IsInt, IsNumber, IsOptional, IsString, Max, MaxLength, Min, MinLength } from 'class-validator';
+
+export class SaveReadingSessionDto {
+  @IsString()
+  @MinLength(1)
+  @MaxLength(64)
+  sessionId!: string;
+
+  @IsDateString()
+  startedAt!: string;
+
+  @IsDateString()
+  endedAt!: string;
+
+  // Client-computed from active reading time (excludes idle and tab-hidden periods).
+  // Server validates it does not exceed the wall-clock span of the session.
+  @IsInt()
+  @Min(0)
+  durationSeconds!: number;
+
+  // Nullable: can be negative if the user navigated backward.
+  @IsOptional()
+  @IsNumber()
+  progressDelta?: number | null;
+
+  @IsOptional()
+  @IsNumber()
+  @Min(0)
+  @Max(100)
+  endProgress?: number | null;
+}

server/src/modules/reading-session/reading-session.controller.ts

@@ -0,0 +1,17 @@
+import { Body, Controller, HttpCode, Param, ParseIntPipe, Post } from '@nestjs/common';
+
+import { CurrentUser } from '../../common/decorators/current-user.decorator';
+import type { RequestUser } from '../../common/types/request-user';
+import { SaveReadingSessionDto } from './dto/save-reading-session.dto';
+import { ReadingSessionService } from './reading-session.service';
+
+@Controller('books/files')
+export class ReadingSessionController {
+  constructor(private readonly service: ReadingSessionService) {}
+
+  @Post(':fileId/sessions')
+  @HttpCode(202)
+  async saveSession(@Param('fileId', ParseIntPipe) fileId: number, @Body() dto: SaveReadingSessionDto, @CurrentUser() user: RequestUser) {
+    await this.service.save(fileId, dto, user);
+  }
+}

server/src/modules/reading-session/reading-session.module.ts

@@ -0,0 +1,14 @@
+import { Module } from '@nestjs/common';
+
+import { BookModule } from '../book/book.module';
+import { ReadingSessionController } from './reading-session.controller';
+import { ReadingSessionRepository } from './reading-session.repository';
+import { ReadingSessionService } from './reading-session.service';
+
+@Module({
+  imports: [BookModule],
+  controllers: [ReadingSessionController],
+  providers: [ReadingSessionService, ReadingSessionRepository],
+  exports: [ReadingSessionRepository],
+})
+export class ReadingSessionModule {}

server/src/modules/reading-session/reading-session.repository.ts

@@ -0,0 +1,107 @@
+import { Inject, Injectable } from '@nestjs/common';
+import { eq, sql } from 'drizzle-orm';
+import type { NodePgDatabase } from 'drizzle-orm/node-postgres';
+
+import { DB } from '../../db';
+import * as schema from '../../db/schema';
+import { bookFiles, books, readingSessions, userReadingDailyStats } from '../../db/schema';
+
+type Db = NodePgDatabase<typeof schema>;
+
+const MIN_SESSION_SECONDS = 10;
+
+@Injectable()
+export class ReadingSessionRepository {
+  constructor(@Inject(DB) private readonly db: Db) {}
+
+  async saveSession(
+    userId: number,
+    bookFileId: number,
+    sessionId: string,
+    startedAt: Date,
+    endedAt: Date,
+    durationSeconds: number,
+    progressDelta: number | null,
+    endProgress: number | null,
+  ): Promise<void> {
+    if (durationSeconds < MIN_SESSION_SECONDS) return;
+
+    const [fileRow] = await this.db
+      .select({ libraryId: books.libraryId })
+      .from(bookFiles)
+      .innerJoin(books, eq(books.id, bookFiles.bookId))
+      .where(eq(bookFiles.id, bookFileId))
+      .limit(1);
+
+    if (!fileRow) return;
+
+    const { libraryId } = fileRow;
+    const day = startedAt.toISOString().slice(0, 10);
+
+    await this.db.transaction(async (tx) => {
+      const inserted = await tx
+        .insert(readingSessions)
+        .values({ userId, bookFileId, sessionId, startedAt, endedAt, durationSeconds, progressDelta, endProgress })
+        .onConflictDoNothing({ target: [readingSessions.sessionId] })
+        .returning({ id: readingSessions.id });
+
+      if (inserted.length === 0) return;
+
+      await tx
+        .insert(userReadingDailyStats)
+        .values({
+          userId,
+          libraryId,
+          day,
+          readingSeconds: durationSeconds,
+          progressDelta: progressDelta ?? 0,
+          sessionsCount: 1,
+          updatedAt: new Date(),
+        })
+        .onConflictDoUpdate({
+          target: [userReadingDailyStats.userId, userReadingDailyStats.libraryId, userReadingDailyStats.day],
+          set: {
+            readingSeconds: sql`${userReadingDailyStats.readingSeconds} + ${durationSeconds}`,
+            progressDelta: sql`${userReadingDailyStats.progressDelta} + ${progressDelta ?? 0}`,
+            sessionsCount: sql`${userReadingDailyStats.sessionsCount} + 1`,
+            updatedAt: new Date(),
+          },
+        });
+    });
+  }
+
+  async recomputeRecentDailyStats(since: Date): Promise<{ deleted: number; inserted: number }> {
+    const sinceDay = since.toISOString().slice(0, 10);
+
+    return this.db.transaction(async (tx) => {
+      const deleteResult = await tx.execute(sql`delete from user_reading_daily_stats where day >= ${sinceDay}::date`);
+
+      const insertResult = await tx.execute(sql`
+        insert into user_reading_daily_stats (user_id, library_id, day, reading_seconds, progress_delta, sessions_count, updated_at)
+        select
+          rs.user_id,
+          b.library_id,
+          date_trunc('day', rs.started_at)::date as day,
+          coalesce(sum(rs.duration_seconds), 0)::int as reading_seconds,
+          coalesce(sum(rs.progress_delta), 0)::real as progress_delta,
+          count(*)::int as sessions_count,
+          now() as updated_at
+        from reading_sessions rs
+        inner join book_files bf on bf.id = rs.book_file_id
+        inner join books b on b.id = bf.book_id
+        where rs.started_at >= ${since}
+        group by rs.user_id, b.library_id, date_trunc('day', rs.started_at)::date
+        on conflict (user_id, library_id, day) do update set
+          reading_seconds = excluded.reading_seconds,
+          progress_delta = excluded.progress_delta,
+          sessions_count = excluded.sessions_count,
+          updated_at = excluded.updated_at
+      `);
+
+      return {
+        deleted: Number((deleteResult as { rowCount?: number }).rowCount ?? 0),
+        inserted: Number((insertResult as { rowCount?: number }).rowCount ?? 0),
+      };
+    });
+  }
+}

server/src/modules/reading-session/reading-session.service.ts

@@ -0,0 +1,37 @@
+import { Injectable } from '@nestjs/common';
+
+import type { RequestUser } from '../../common/types/request-user';
+import { BookService } from '../book/book.service';
+import type { SaveReadingSessionDto } from './dto/save-reading-session.dto';
+import { ReadingSessionRepository } from './reading-session.repository';
+
+@Injectable()
+export class ReadingSessionService {
+  constructor(
+    private readonly repo: ReadingSessionRepository,
+    private readonly bookService: BookService,
+  ) {}
+
+  async save(fileId: number, dto: SaveReadingSessionDto, user: RequestUser): Promise<void> {
+    await this.bookService.verifyFileAccess(fileId, user);
+
+    const startedAt = new Date(dto.startedAt);
+    const endedAt = new Date(dto.endedAt);
+    const wallClockSeconds = Math.max(0, Math.floor((endedAt.getTime() - startedAt.getTime()) / 1000));
+
+    // Client sends active reading time (excludes idle/hidden periods); cap it at the wall-clock
+    // span to prevent the client from reporting more time than physically elapsed.
+    const durationSeconds = Math.min(dto.durationSeconds, wallClockSeconds);
+
+    await this.repo.saveSession(
+      user.id,
+      fileId,
+      dto.sessionId,
+      startedAt,
+      endedAt,
+      durationSeconds,
+      dto.progressDelta ?? null,
+      dto.endProgress ?? null,
+    );
+  }
+}

server/src/modules/user-statistics/user-statistics.repository.ts

@@ -1,5 +1,5 @@
 import { Inject, Injectable } from '@nestjs/common';
-import { and, eq, gte, inArray, lt, sql } from 'drizzle-orm';
+import { and, eq, gte, inArray, isNotNull, lt, sql } from 'drizzle-orm';
 import type { NodePgDatabase } from 'drizzle-orm/node-postgres';
 
 import type {
@@ -13,7 +13,7 @@ import type {
 
 import { DB } from '../../db';
 import * as schema from '../../db/schema';
-import { bookFiles, books, readingProgress, readingSessionEvents, userLibraryAccess, userReadingDailyStats } from '../../db/schema';
+import { bookFiles, books, readingProgress, readingSessions, userLibraryAccess, userReadingDailyStats } from '../../db/schema';
 
 type Db = NodePgDatabase<typeof schema>;
 const RECENT_DAILY_AGGREGATION_DAYS = 2;
@@ -104,7 +104,7 @@ export class UserStatisticsRepository {
         day: userReadingDailyStats.day,
         readingSeconds: sql<number>`coalesce(sum(${userReadingDailyStats.readingSeconds}), 0)::int`,
         progressDelta: sql<number>`coalesce(sum(${userReadingDailyStats.progressDelta}), 0)::float`,
-        eventsCount: sql<number>`coalesce(sum(${userReadingDailyStats.eventsCount}), 0)::int`,
+        eventsCount: sql<number>`coalesce(sum(${userReadingDailyStats.sessionsCount}), 0)::int`,
       })
       .from(userReadingDailyStats)
       .where(and(eq(userReadingDailyStats.userId, userId), gte(userReadingDailyStats.day, sinceDay), libraryFilter))
@@ -116,18 +116,18 @@ export class UserStatisticsRepository {
     const accessible = await this.getAccessibleLibraryIds(userId, isSuperuser);
     const libraryFilter = this.libraryFilter(this.intersectLibraryIds(accessible, filterLibraryIds));
     const since = this.sinceDateForDays(days);
-    const hourExpr = sql<number>`extract(hour from ${readingSessionEvents.recordedAt})::int`;
+    const hourExpr = sql<number>`extract(hour from ${readingSessions.startedAt})::int`;
 
     return this.db
       .select({
         hour: hourExpr,
-        readingSeconds: sql<number>`coalesce(sum(case when ${readingSessionEvents.deltaSeconds} > 0 and ${readingSessionEvents.deltaSeconds} <= 1800 then ${readingSessionEvents.deltaSeconds} else 0 end), 0)::int`,
+        readingSeconds: sql<number>`coalesce(sum(${readingSessions.durationSeconds}), 0)::int`,
         eventsCount: sql<number>`count(*)::int`,
       })
-      .from(readingSessionEvents)
-      .innerJoin(bookFiles, eq(bookFiles.id, readingSessionEvents.bookFileId))
+      .from(readingSessions)
+      .innerJoin(bookFiles, eq(bookFiles.id, readingSessions.bookFileId))
       .innerJoin(books, eq(books.id, bookFiles.bookId))
-      .where(and(eq(readingSessionEvents.userId, userId), gte(readingSessionEvents.recordedAt, since), libraryFilter))
+      .where(and(eq(readingSessions.userId, userId), gte(readingSessions.startedAt, since), libraryFilter))
       .groupBy(hourExpr)
       .orderBy(hourExpr);
   }
@@ -136,18 +136,18 @@ export class UserStatisticsRepository {
     const accessible = await this.getAccessibleLibraryIds(userId, isSuperuser);
     const libraryFilter = this.libraryFilter(this.intersectLibraryIds(accessible, filterLibraryIds));
     const since = this.sinceDateForDays(days);
-    const dayOfWeekExpr = sql<number>`extract(dow from ${readingSessionEvents.recordedAt})::int`;
+    const dayOfWeekExpr = sql<number>`extract(dow from ${readingSessions.startedAt})::int`;
 
     return this.db
       .select({
         dayOfWeek: dayOfWeekExpr,
-        readingSeconds: sql<number>`coalesce(sum(case when ${readingSessionEvents.deltaSeconds} > 0 and ${readingSessionEvents.deltaSeconds} <= 1800 then ${readingSessionEvents.deltaSeconds} else 0 end), 0)::int`,
+        readingSeconds: sql<number>`coalesce(sum(${readingSessions.durationSeconds}), 0)::int`,
         eventsCount: sql<number>`count(*)::int`,
       })
-      .from(readingSessionEvents)
-      .innerJoin(bookFiles, eq(bookFiles.id, readingSessionEvents.bookFileId))
+      .from(readingSessions)
+      .innerJoin(bookFiles, eq(bookFiles.id, readingSessions.bookFileId))
       .innerJoin(books, eq(books.id, bookFiles.bookId))
-      .where(and(eq(readingSessionEvents.userId, userId), gte(readingSessionEvents.recordedAt, since), libraryFilter))
+      .where(and(eq(readingSessions.userId, userId), gte(readingSessions.startedAt, since), libraryFilter))
       .groupBy(dayOfWeekExpr)
       .orderBy(dayOfWeekExpr);
   }
@@ -165,12 +165,12 @@ export class UserStatisticsRepository {
     const firstCompletion = this.db
       .select({
         bookId: bookFiles.bookId,
-        firstCompletedAt: sql<Date>`min(${readingSessionEvents.recordedAt})`.as('first_completed_at'),
+        firstCompletedAt: sql<Date>`min(${readingSessions.endedAt})`.as('first_completed_at'),
       })
-      .from(readingSessionEvents)
-      .innerJoin(bookFiles, eq(bookFiles.id, readingSessionEvents.bookFileId))
+      .from(readingSessions)
+      .innerJoin(bookFiles, eq(bookFiles.id, readingSessions.bookFileId))
       .innerJoin(books, eq(books.id, bookFiles.bookId))
-      .where(and(eq(readingSessionEvents.userId, userId), gte(readingSessionEvents.percentage, 100), libraryFilter))
+      .where(and(eq(readingSessions.userId, userId), gte(readingSessions.endProgress, 100), libraryFilter))
       .groupBy(bookFiles.bookId)
       .as('first_completion');
 
@@ -208,18 +208,18 @@ export class UserStatisticsRepository {
     const accessible = await this.getAccessibleLibraryIds(userId, isSuperuser);
     const libraryFilter = this.libraryFilter(this.intersectLibraryIds(accessible, filterLibraryIds));
     const timeFilter = untilExclusive
-      ? and(gte(readingSessionEvents.recordedAt, since), lt(readingSessionEvents.recordedAt, untilExclusive))
-      : gte(readingSessionEvents.recordedAt, since);
+      ? and(gte(readingSessions.startedAt, since), lt(readingSessions.startedAt, untilExclusive))
+      : gte(readingSessions.startedAt, since);
 
     const perBookProgress = this.db
       .select({
         bookId: bookFiles.bookId,
-        maxPercentage: sql<number>`max(${readingSessionEvents.percentage})`.as('max_percentage'),
+        maxPercentage: sql<number>`max(${readingSessions.endProgress})`.as('max_percentage'),
       })
-      .from(readingSessionEvents)
-      .innerJoin(bookFiles, eq(bookFiles.id, readingSessionEvents.bookFileId))
+      .from(readingSessions)
+      .innerJoin(bookFiles, eq(bookFiles.id, readingSessions.bookFileId))
       .innerJoin(books, eq(books.id, bookFiles.bookId))
-      .where(and(eq(readingSessionEvents.userId, userId), timeFilter, libraryFilter))
+      .where(and(eq(readingSessions.userId, userId), timeFilter, libraryFilter, isNotNull(readingSessions.endProgress)))
       .groupBy(bookFiles.bookId)
       .as('per_book_progress');
 
@@ -250,33 +250,24 @@ export class UserStatisticsRepository {
     const completedInWindow = this.db
       .select({
         bookId: bookFiles.bookId,
-        completedAt: sql<Date>`min(${readingSessionEvents.recordedAt})`.as('completed_at'),
+        completedAt: sql<Date>`min(${readingSessions.endedAt})`.as('completed_at'),
       })
-      .from(readingSessionEvents)
-      .innerJoin(bookFiles, eq(bookFiles.id, readingSessionEvents.bookFileId))
+      .from(readingSessions)
+      .innerJoin(bookFiles, eq(bookFiles.id, readingSessions.bookFileId))
       .innerJoin(books, eq(books.id, bookFiles.bookId))
-      .where(
-        and(
-          eq(readingSessionEvents.userId, userId),
-          gte(readingSessionEvents.recordedAt, since),
-          gte(readingSessionEvents.percentage, 100),
-          libraryFilter,
-        ),
-      )
+      .where(and(eq(readingSessions.userId, userId), gte(readingSessions.startedAt, since), gte(readingSessions.endProgress, 100), libraryFilter))
       .groupBy(bookFiles.bookId)
       .as('completed_in_window');
 
     const startedAndCompleted = this.db
       .select({
         completedAt: completedInWindow.completedAt,
-        startedAt: sql<Date | null>`min(case when ${readingSessionEvents.percentage} > 0 then ${readingSessionEvents.recordedAt} end)`.as(
-          'started_at',
-        ),
+        startedAt: sql<Date | null>`min(${readingSessions.startedAt})`.as('started_at'),
       })
-      .from(readingSessionEvents)
-      .innerJoin(bookFiles, eq(bookFiles.id, readingSessionEvents.bookFileId))
+      .from(readingSessions)
+      .innerJoin(bookFiles, eq(bookFiles.id, readingSessions.bookFileId))
       .innerJoin(completedInWindow, eq(completedInWindow.bookId, bookFiles.bookId))
-      .where(eq(readingSessionEvents.userId, userId))
+      .where(eq(readingSessions.userId, userId))
       .groupBy(completedInWindow.bookId, completedInWindow.completedAt)
       .as('started_and_completed');
 
@@ -298,30 +289,22 @@ export class UserStatisticsRepository {
 
     return this.db.transaction(async (tx) => {
       const deleteResult = await tx.execute(sql`delete from user_reading_daily_stats where day >= ${sinceDay}::date`);
+
       const insertResult = await tx.execute(sql`
-        insert into user_reading_daily_stats (user_id, library_id, day, reading_seconds, progress_delta, events_count, updated_at)
+        insert into user_reading_daily_stats (user_id, library_id, day, reading_seconds, progress_delta, sessions_count, updated_at)
         select
-          ${readingSessionEvents.userId} as user_id,
-          ${books.libraryId} as library_id,
-          date_trunc('day', ${readingSessionEvents.recordedAt})::date as day,
-          coalesce(
-            sum(
-              case
-                when ${readingSessionEvents.deltaSeconds} > 0 and ${readingSessionEvents.deltaSeconds} <= 1800
-                  then ${readingSessionEvents.deltaSeconds}
-                else 0
-              end
-            ),
-            0
-          )::int as reading_seconds,
-          coalesce(sum(${readingSessionEvents.percentageDelta}), 0)::real as progress_delta,
-          count(*)::int as events_count,
+          rs.user_id,
+          b.library_id,
+          date_trunc('day', rs.started_at)::date as day,
+          coalesce(sum(rs.duration_seconds), 0)::int as reading_seconds,
+          coalesce(sum(rs.progress_delta), 0)::real as progress_delta,
+          count(*)::int as sessions_count,
           now() as updated_at
-        from ${readingSessionEvents}
-        inner join ${bookFiles} on ${bookFiles.id} = ${readingSessionEvents.bookFileId}
-        inner join ${books} on ${books.id} = ${bookFiles.bookId}
-        where ${readingSessionEvents.recordedAt} >= ${since}
-        group by ${readingSessionEvents.userId}, ${books.libraryId}, date_trunc('day', ${readingSessionEvents.recordedAt})::date
+        from reading_sessions rs
+        inner join book_files bf on bf.id = rs.book_file_id
+        inner join books b on b.id = bf.book_id
+        where rs.started_at >= ${since}
+        group by rs.user_id, b.library_id, date_trunc('day', rs.started_at)::date
       `);
 
       const deleted = Number((deleteResult as { rowCount?: number }).rowCount ?? 0);