Continue row: a run of more than N chapters in order also marks a reread

A done chapter after the head now counts as left again when it was finished more than rereadDays before the head (default 7) or before a run of more than rereadChapters chapters read in order up to the head (default 5). Both are user settings under Library page; 0 turns a rule off. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Continue row: only manga with something left after the last chapter read
2026-11-01 11:47:45 +01:00 · 2026-11-01 11:27:02 +01:00 · 2026-10-31 12:21:24 +01:00 · 2026-10-31 11:49:52 +01:00 · 2026-10-31 11:45:44 +01:00
16 changed files with 701 additions and 58 deletions
@@ -11,6 +11,7 @@
 !reading-analytics.js
 !reading-access.js
 !moments.js
+!reader-sessions.js
 !public/
 !public/**
 !greatest/
@@ -3,7 +3,7 @@ RUN apk add --no-cache tzdata openssl
 WORKDIR /app
 ARG VCS_REF=development
 LABEL org.opencontainers.image.title="MangaCircus" org.opencontainers.image.revision=$VCS_REF
-COPY package.json server.js library.js reading-direction.js chapter-identity.js chapter-dates.js reading-analytics.js reading-access.js catalog.js backup.js moments.js ./
+COPY package.json server.js library.js reading-direction.js chapter-identity.js chapter-dates.js reading-analytics.js reading-access.js catalog.js backup.js moments.js reader-sessions.js ./
 COPY public ./public
 COPY greatest ./greatest
 COPY discovery ./discovery
@@ -50,6 +50,10 @@ Settings has **User** and **Admin** menu groups. User sections cover Reading, Re
 Notifications and Account. Admin sections cover Scraper, Server & library, Users & access, Collections &
 metadata and Service health. Only admins see administration ([settings navigation](docs/settings-navigation.md)).

+Reader settings (mode, zoom, page tone, skipping) are kept per sign-in: each device or browser keeps its own once you
+change one there, and a new sign-in starts from the one you used last. **Settings → Reading → Reader settings per
+session** shows every session's state and turns this off for one shared set ([details](docs/architecture.md#67-reader-settings-per-session)).
+
 ### Settings (environment variables)

 These configure the reader process. In Docker most are set for you by `docker-compose.yml`; the variables
@@ -144,7 +148,7 @@ completeness.
 - **Flow page gap:** Settings → Reading lets each user keep the normal separator between Flow pages or remove it for continuous webtoon artwork and text that crosses image edges.
 - **Page tone:** the reader's **Tone** button cycles Original → Inverted → Sepia → Dim → Extra dim in Flow, Page and Book. It changes only the artwork, never the controls or site theme. The choice is saved per user; it can also be selected in Settings → User → Reading.
 - **Active Reading Clock:** opt in under Settings → User → Reading time & privacy. No scrolling-speed limit; a visit counts at 60% viewed-page coverage and saves on exit. Pauses in the background or after 30 seconds without reader activity. Tap the clock for this visit's time, coverage, qualification and loading wait.
- **Continue where you left off:** the first line of the library content (below the search, filters and tags) is one row of the five manga you read most recently and have not finished (same tiles as the grid; they stay in the grid too). It hides while a search is typed, a status filter is set, or the library is sorted by *Recently read*; tags and collection grouping do not affect it. Turn it off under Settings → User → Reading → *Library page*.
+- **Continue where you left off:** the first line of the library content (below the search, filters and tags) is one row of the five manga you read most recently that still have something left after the last chapter you read (same tiles as the grid; they stay in the grid too). Left means an unfinished last chapter, an unread later chapter, or — when you are rereading — a later chapter you finished in an earlier pass: more than *N days* before your current position (default 7), or before a run of more than *M chapters* you have since read in order up to it (default 5). Both are set under Settings → User → Reading → *Library page*; 0 turns a rule off. A manga you have caught up on drops out until a new chapter arrives. It hides while a search is typed, a status filter is set, or the library is sorted by *Recently read*; tags and collection grouping do not affect it. Turn it off under Settings → User → Reading → *Library page*.
 - **Your Reading Story:** private active-time summaries appear on the library and manga pages when history exists. Chapter rows show the last timed read (60%-coverage visit), rereads remain visible as lifetime time, and Settings lets each user hide, export, or delete their own history. No leaderboards or speed ranking are used.
 - **Tap / click zones:**
  - Tapping **beside the pages** always shows or hides the controls.
@@ -129,12 +129,17 @@ This keeps ids human-readable and derivable without a database. The price: renam
        "readingClock": false,           // opt in to credible per-chapter active-time tracking
        "readingStory": true,            // show private retrospective summaries when history exists
        "continueRow": true,             // library: "Continue where you left off" row at the top
+        "rereadDays": 7,                 // continue row: a later chapter finished this long before the head is left again (0 = off)
+        "rereadChapters": 5,             // ... or one finished before a run of more than this many in-order chapters (0 = off)
        "zoom": { "flow": 1, "page": 1.5, "book": 1, "strip": 0.8 },   // page zoom per mode
-        "webhook": ""
-      }
+        "webhook": "",
+        "readerPerSession": true        // reader settings per login session (section 6.7)
+      },
+      "readerFrom": "3f9c…"            // public id of the session the latest reader settings came from
    }
  },
-  "sessions":  { "<sha256 of token>": { "u": "admin", "t": 1790796794000 } },
+  "sessions":  { "<sha256 of token>": { "u": "admin", "t": 1790796794000, "seen": 1790796794000,
+                  "agent": "<User-Agent>", "reader": { …locked reader settings, only after a change… } } },
  "progress":  { "admin": { "Moon Garden": { "1/2": {
                  "v": "c0002 Roots [MangaDex]",  // version read
                  "p": 4, "n": 14,                // page index in that version (all pages), page count
@@ -177,7 +182,7 @@ This keeps ids human-readable and derivable without a database. The price: renam

 | Path | Handling |
 |------|----------|
-| `/api/*` | `routes["<METHOD> <path>"]`. Handlers get `{ u, b, q, req, res }` and return an object, which is sent as JSON. Throwing `HttpError(code, message, extra)` sends `{ error, ...extra }` with that status (for example `nextAllowedAt` on a discovery `429`) |
+| `/api/*` | `routes["<METHOD> <path>"]`. Handlers get `{ u, b, q, req, res, sess, sk }` (`sess` = the login session record, `sk` its key) and return an object, which is sent as JSON. Throwing `HttpError(code, message, extra)` sends `{ error, ...extra }` with that status (for example `nextAllowedAt` on a discovery `429`) |
 | `/lib/*` | Image files from `LIBRARY`. Requires a session, allows image extensions only, and the path must resolve inside `LIBRARY`. `ETag` + `private, max-age=86400` |
 | everything else | Static files from `public/` (`/` → `index.html`). `ETag` + `no-cache` |

@@ -194,12 +199,15 @@ All requests and responses are JSON. POSTs require `Content-Type: application/js
 | `POST /api/login` `{name, password}` | public | Starts a session (cookie `sid`) |
 | `POST /api/logout` | user | Ends the session |
 | `GET /api/me` | user | Name, admin flag, settings, unread count |
-| `POST /api/settings` `{…partial}` | user | Validated update of the settings keys above |
+| `POST /api/settings` `{…partial}` | user | Validated update of the settings keys above; reader keys go to the current session (6.7) |
+| `GET /api/reader-sessions` | user | `{ enabled, current, latestFrom, latest, sessions: [{ id, device, created, seen, current, locked, reader }] }` |
+| `POST /api/reader-sessions` `{id, action}` | user | `follow`: the session drops its own reader settings and follows the latest; `latest`: its settings become the latest |
 | `POST /api/password` `{old, new}` | user | Change password |
-| `GET /api/library` | user | Manga list with covers, counts, the user's read count, unread notifications, last read, and optional personal Reading Story aggregates |
+| `GET /api/library` | user | Manga list with covers, counts, the user's read count, unread notifications, last read, `left` (chapters after the newest saved position that are unfinished, unread, or finished in an earlier pass — over `rereadDays` before it, or before a run of more than `rereadChapters` chapters read in order up to it; 0 = caught up), and optional personal Reading Story aggregates |
 | `GET /api/manga?m=` | user | Manga details, books, chapters with ranked versions, progress, optional chapter-time summaries, and `continue` target |
-| `GET /api/chapter?m=&c=[&v=]` | user | Pages (`u, w, h, t, r`), direction, versions, prev/next, progress, optional Active Reading Clock summary, plus all books and chapters of the manga (with the user's read state) for the chapter picker. Also marks that chapter's notifications read |
-| `POST /api/progress` `{m, c, v, p, n, done, shift}` | user | Save the reading position |
+| `GET /api/chapter?m=&c=[&v=]` | user | Pages (`u, w, h, t, r`), direction, versions, prev/next, progress, `latest` (as in `/api/progress/latest`), optional Active Reading Clock summary, plus all books and chapters of the manga (with the user's read state) for the chapter picker. Also marks that chapter's notifications read |
+| `POST /api/progress` `{m, c, v, p, n, done, shift[, tab, seen]}` | user | Save the reading position. With `seen`, a save is refused (`{ok:false, stale:true, latest}`) when another tab saved a newer position of this manga since; otherwise `{ok:true, t}` |
+| `GET /api/progress/latest?m=` | user | The manga's newest saved position (`latest`: `t, w, c, label, v, p, n, done, continue`) or `null` |
 | `POST /api/reading/pulse` `{m, c, v, session, seq, …deltas}` | user | When opted in, idempotently merge a clamped active-time pulse, verified page coverage and input totals under a single-reader lease |
 | `GET /api/reading/export` | user | Export the user's private derived reading-time summary without raw input or page-exposure diagnostics |
 | `POST /api/reading/delete` `{m}` or `{all:true,password}` | user | Delete one manga's reading history, or all history after password confirmation, without changing normal reading progress |
@@ -269,6 +277,22 @@ The reader alone talks to AniList for discovery ([discovery.md](discovery.md)).
  (all reasons, strongest first) next to `reason`; seed evidence carries `fetchedAt`.
 - `DISCOVERY_ANILIST_URL` overrides the AniList endpoint (tests point it at a local fixture server).

+### 6.7 Reader settings per session
+
+The reader keys (`startMode`, `lastMode`, `adapt`, `skipExtras`, `skipCovers`, `flowPageGap`, `pageTone`, `zoom`)
+can differ per login session, so a phone and a desktop keep their own mode and zoom (`reader-sessions.js`):
+
+- `user.settings` holds the **latest** reader set. A session without its own set follows it.
+- The first reader change in a session copies the latest set into `session.reader` with the change applied: the session
+  is now **locked** and keeps that set whatever other sessions do. The change also becomes the latest set.
+- Loading a page (`GET /api/me`) from a locked session makes its set the latest again, so a new sign-in starts from the
+  session used last. A new sign-in has no set of its own until it changes something.
+- Other settings (Reading Story, dates, discovery, webhook, …) stay per user.
+- `readerPerSession: false` (Settings → Reading) brings back one shared set: changes go to `user.settings` and apply to
+  every session. Locked sets are kept and apply again when the switch is turned back on.
+
+Settings → Reading → *Reader settings per session* lists the user's sessions (device from the User-Agent, sign-in and last
+activity, own or following) with "Follow latest again" and "Use for new sessions".
 ## 7. Frontend

 ### 7.1 Pages
@@ -352,6 +376,7 @@ mode       = adapt && intended ∉ compatible ? compatible[0] : intended
 - Saved 700 ms after the position settles, and on `pagehide` (a `fetch` with `keepalive`).
 - Stores the page index in the full page list, so skipping extras doesn't corrupt it.
 - On open, the saved page is used for the same version, and mapped proportionally for another version. A finished chapter reopens at the start.
+- **Stale reading sessions.** A tab left open on one device (or restored by the browser) must not move "Continue" back after the user read on elsewhere. Each browser tab has an id (`sessionStorage`) that its saves store as `w`; reader links carry `at`, the newest progress time the linking page knew (`continue.at`), and the reader keeps `at` current in its address bar so a reload or restored tab still knows it. A link without `at` (bookmark, notification) counts as a deliberate open. When the manga's newest position is later than `at` and came from another tab, the reader saves nothing and asks: jump to the newest position, or keep reading here, which makes this chapter the head again. It checks on open, when the tab becomes visible again, and with every save (the server refuses the stale save). The comparison is by save time, not chapter order; the question names no device.

 **Active Reading Clock (opt-in):**
 - Runs only while the reader is visible and focused, a sufficiently exposed page is decoded, a server lease is held, and accepted reader input occurred in the last 50 seconds.
@@ -387,6 +387,8 @@ main { max-width: 1200px; margin: 0 auto; padding: 16px; }
 .login input { width: 100%; }
 .saved { color: #7fd3a0; font-size: 13px; }
 .reading-data { margin-top: 16px; padding-top: 12px; border-top: 1px solid var(--line); }
+.reader-sessions { list-style: none; margin: 12px 0 0; padding: 0; }
+.reader-sessions li { display: grid; gap: 4px; padding: 10px 0; border-top: 1px solid var(--line); overflow-wrap: anywhere; }
 .reading-data > summary { cursor: pointer; font-weight: 600; }
 .reading-danger { margin-top: 14px; padding-top: 12px; border-top: 1px solid var(--line); }
 .reading-danger p { margin: 3px 0 8px; }
@@ -429,6 +431,14 @@ body.reader { position: fixed; top: 0; left: 0; right: 0; bottom: 0; overflow: h
 .reading-gate-message[data-tone="retry"] { border-color: #9b7233; background: #382b1a; color: #ffdaa0; }
 .reading-gate-message[data-tone="error"] { border-color: #944c55; background: #3c2025; color: #ffc0c6; }
@media (max-width: 660px) { .reading-gate { margin: 28px 12px 100px; padding: 18px; } }
+/* Stale reading session: a newer position was saved elsewhere since this page was opened. */
+.stale-session { position: fixed; inset: 0; z-index: 60; display: flex; align-items: center; justify-content: center;
+  padding: 16px; background: rgba(0, 0, 0, .6); }
+.stale-box { box-sizing: border-box; width: min(440px, 100%); padding: 20px; border-radius: 12px; background: var(--card);
+  border: 1px solid var(--line); box-shadow: 0 12px 40px rgba(0, 0, 0, .6); }
+.stale-box h2 { margin: 0 0 8px; font-size: 18px; }
+.stale-actions { display: flex; flex-wrap: wrap; gap: 10px; margin: 16px 0 10px; }
+.stale-actions .btn { flex: 1 1 auto; justify-content: center; text-align: center; }
 .pg { position: absolute; overflow: hidden; background: #19191c; }
 .pg img { display: block; width: 100%; height: 100%; -webkit-user-drag: none; }
 #canvas[data-page-tone="inverted"] .pg img { filter: invert(1); }
@@ -8,7 +8,7 @@
      h('div', { class: 'info' }, h('h1', {}, c.title), h('p', { class: 'muted' }, `${c.members.length} manga · ${c.read}/${c.chapters} chapters read · ${c.unread} new`),
        c.description ? h('p', {}, c.description) : null,
        c.reading.activeMs ? h('p', {}, `${readingDuration(c.reading.activeMs)} together`) : null,
-        h('div', { class: 'actions' }, h('a', { class: 'btn primary', href: readUrl(c.continue.m, c.continue.c, c.continue.v) }, c.continue.text),
+        h('div', { class: 'actions' }, h('a', { class: 'btn primary', href: readUrl(c.continue.m, c.continue.c, c.continue.v, c.continue.at) }, c.continue.text),
          me.admin ? h('a', { class: 'btn', href: 'collections.html?' + qsa({ id: c.id }) }, 'Edit collection') : null))));
    main.append(h('h2', {}, 'Reading order'), h('div', { class: 'collection-members' }, c.members.map(m =>
      h('a', { class: 'collection-member', href: mangaUrl(m.id) }, m.cover ? h('img', { src: m.cover, alt: '', loading: 'lazy' }) : null,
@@ -39,6 +39,20 @@ const store = {
  get(k) { try { return localStorage.getItem('mc.' + k); } catch (e) { return null; } },
  set(k, v) { try { localStorage.setItem('mc.' + k, v); } catch (e) { /* private mode */ } },
 };
+// One id per browser tab (it survives navigation and reloads in that tab): progress saves carry it, so
+// a reader can tell its own saves from those of another tab or device.
+const tabId = (() => {
+  let id = null;
+  return () => {
+    if (id) return id;
+    try { id = sessionStorage.getItem('mc.tab'); } catch (e) { /* storage blocked */ }
+    if (!/^[a-zA-Z0-9_-]{8,40}$/.test(id || '')) {
+      id = Array.from(crypto.getRandomValues(new Uint8Array(12)), b => b.toString(16).padStart(2, '0')).join('');
+      try { sessionStorage.setItem('mc.tab', id); } catch (e) { /* this page keeps it in memory */ }
+    }
+    return id;
+  };
+})();

 function ago(t) {
  const s = (Date.now() - t) / 1000;
@@ -60,7 +74,8 @@ function readingDuration(ms, compact = false) {
 }

 const qsa = obj => { const p = new URLSearchParams(); for (const k in obj) if (obj[k] != null && obj[k] !== '') p.set(k, obj[k]); return p.toString(); };
-const readUrl = (m, c, v) => 'read.html?' + qsa({ m, c, v });
+// `at`: the manga's latest progress time the linking page knew, so the reader can tell it opened from a stale page.
+const readUrl = (m, c, v, at) => 'read.html?' + qsa({ m, c, v, at: at || null });
 const mangaUrl = m => 'manga.html?' + qsa({ m });
 const libraryUrlForTags = tags => {
  const p = new URLSearchParams();
@@ -55,8 +55,9 @@
    h('option', { value: 'grouped' }, 'Group collections'), h('option', { value: 'expanded' }, 'Expand collections'), h('option', { value: 'individual' }, 'Individual manga'));
  grouping.value = ['grouped', 'expanded', 'individual'].includes(store.get('grouping')) ? store.get('grouping') : 'grouped';
  grouping.onchange = render;
-  // Started but unfinished manga, most recently read first; the same manga still appear in the grid.
-  const continueItems = data.mangas.filter(m => m.lastRead && m.read < m.chapters)
+  // Started manga with chapters left after the last one read (first read or reread, server `left`),
+  // most recently read first; the same manga still appear in the grid.
+  const continueItems = data.mangas.filter(m => m.lastRead && m.left > 0)
    .sort((a, b) => b.lastRead - a.lastRead).slice(0, 5);
  const continueRow = h('section', { class: 'continue-row', 'aria-label': 'Continue where you left off', hidden: true },
    h('div', { class: 'continue-banner' }, h('span', { 'aria-hidden': 'true' }, '▶'), 'Continue where you left off'),
@@ -72,7 +73,7 @@
        data.reading.rereads ? h('span', { class: 'story-pill' }, `${data.reading.rereads} reread${data.reading.rereads === 1 ? '' : 's'}`) : null),
      h('div', { class: 'reading-summary-links' },
        most ? h('a', { href: mangaUrl(most.id) }, `Most time with ${most.title}`) : null,
-        latest && data.reading.lastChapterId ? h('a', { href: readUrl(latest.id, data.reading.lastChapterId) }, `Continue ${latest.title} →`) : null)));
+        latest && data.reading.lastChapterId ? h('a', { href: readUrl(latest.id, data.reading.lastChapterId, null, latest.lastRead) }, `Continue ${latest.title} →`) : null)));
  }
  main.append(
    h('div', { class: 'library-controls' },
@@ -48,7 +48,7 @@
      h('div', { class: 'chips' }, tags.map(tag => h('a', { class: 'chip chip-link', href: libraryUrlForTags([tag]), title: `Show manga tagged ${tag}` }, tag))),
      meta.description ? h('p', { class: 'desc' }, meta.description) : null,
      h('div', { class: 'actions' },
-        M.continue ? h('a', { class: 'btn primary', href: readUrl(M.id, M.continue.c, M.continue.v) }, M.continue.text) : null,
+        M.continue ? h('a', { class: 'btn primary', href: readUrl(M.id, M.continue.c, M.continue.v, M.continue.at) }, M.continue.text) : null,
        follow))));

  let storyRhythm = null;
@@ -73,7 +73,7 @@
        storyStat(M.reading.typicalChapterMs ? readingDuration(M.reading.typicalChapterMs) : '—', 'typical chapter'),
        storyStat(M.reading.rereads, `reread${M.reading.rereads === 1 ? '' : 's'}`)),
      lastChapter ? h('p', { class: 'story-last muted' }, 'Last timed ',
-        h('a', { href: readUrl(M.id, lastChapter.id) }, `${lastChapter.label}${lastChapter.title ? ' · ' + lastChapter.title : ''}`),
+        h('a', { href: readUrl(M.id, lastChapter.id, null, M.continue?.at) }, `${lastChapter.label}${lastChapter.title ? ' · ' + lastChapter.title : ''}`),
        ` · ${ago(M.reading.updatedAt)}`) : null,
      h('div', { class: 'story-rhythm-head' }, h('b', {}, 'Reading rhythm'), h('span', { class: 'muted small' }, 'Completed chapters · active time')),
      storyRhythm,
@@ -110,7 +110,7 @@
      const passes = chapter.reading.completedPasses;
      const title = `${label} · ${readingDuration(value)}${passes > 1 ? ` · ${passes} timed reads · ${readingDuration(chapter.reading.totalActiveMs)} total` : ''}`;
      storyRhythm.append(h('a', {
-        class: 'rhythm-bar', role: 'listitem', href: readUrl(M.id, chapter.id), title,
+        class: 'rhythm-bar', role: 'listitem', href: readUrl(M.id, chapter.id, null, M.continue?.at), title,
        'aria-label': title, style: `height:${height}px`,
      }));
    }
@@ -221,7 +221,7 @@
        if (done) { await api('api/unread', { m: M.id, c: ch.id }); ch.progress = null; ch.readAt = null; }
        else {
          const version = ch.versions[0];
-          await api('api/progress', { m: M.id, c: ch.id, v: version.id, p: version.pages - 1, n: version.pages, done: true });
+          await api('api/progress', { m: M.id, c: ch.id, v: version.id, p: version.pages - 1, n: version.pages, done: true, tab: tabId() });
          ch.progress = { v: version.id, p: version.pages - 1, n: version.pages, done: true };
          ch.readAt = { at: Date.now(), approx: false };
        }
@@ -234,7 +234,7 @@
      const timing = chapterTiming(ch), released = chapterRelease(ch.dates);
      wrap.textContent = '';
      wrap.append(h('div', { class: 'ch' + (done ? ' read' : '') },
-        h('a', { class: 'ch-main' + (timing ? ' has-time' : '') + (M.chapterDates?.release ? ' has-date' : ''), href: readUrl(M.id, ch.id) },
+        h('a', { class: 'ch-main' + (timing ? ' has-time' : '') + (M.chapterDates?.release ? ' has-date' : ''), href: readUrl(M.id, ch.id, null, M.continue?.at) },
          h('span', { class: 'ch-label' }, ch.label),
          h('span', { class: 'ch-pages' }, `${pages} p.`),
          M.chapterDates?.release ? h('span', { class: 'ch-date' + (released ? ' tier-' + released.tier : ''), title: released ? released.title : 'No date known', 'aria-label': released ? released.title : 'No date known' },
@@ -259,7 +259,7 @@
            h('button', { class: version.my > 0 ? 'on' : '', title: 'Better', onclick: () => vote(1) }, '▲'),
            h('b', {}, version.score),
            h('button', { class: version.my < 0 ? 'on' : '', title: 'Worse', onclick: () => vote(-1) }, '▼')),
-          h('a', { class: 'btn small', href: readUrl(M.id, ch.id, version.id) }, 'Read')));
+          h('a', { class: 'btn small', href: readUrl(M.id, ch.id, version.id, M.continue?.at) }, 'Read')));
      });
    }
    draw();
@@ -155,6 +155,55 @@
  // A link to a page (e.g. "Open in reader" from a moment) wins over the saved position.
  if (P.get('p') != null) { const k = list.findIndex(x => x.i >= +P.get('p')); if (k >= 0) cur = k; }

+  // Stale reading sessions: a tab left open (or restored by the browser) on another device must not move
+  // the "Continue" point back. `seen` is the newest progress time this tab knows: the link's `at`, kept
+  // current in the address bar, so a reload or restored tab still knows it. Without `at` the open was a
+  // deliberate one (bookmark, notification) and starts from the current head.
+  const tab = tabId();
+  let seen = Number(P.get('at')) || (D.latest ? D.latest.t : 0), stale = null, staleCard = null;
+  const chapterUrl = (c, v) => readUrl(D.manga.id, c, v, seen);
+  const newer = latest => !!latest && latest.t > seen && latest.w !== tab;
+  function markSeen(t) {
+    seen = Math.max(seen, t || 0);
+    const q = new URLSearchParams(location.search);
+    q.set('at', seen);
+    history.replaceState(history.state, '', '?' + q);
+  }
+  // Another tab or device saved a newer position. The same place is no conflict; anything else asks.
+  function checkLatest(latest) {
+    if (!newer(latest)) return;
+    if (latest.c === D.chapter.id && list[cur] && latest.p === list[cur].i) { markSeen(latest.t); return; }
+    showStale(latest);
+  }
+  function showStale(latest) {
+    stale = latest;
+    clearTimeout(saveTimer);
+    if (staleCard) staleCard.remove();
+    const where = latest.done ? `${latest.label} (finished)` : `${latest.label} · page ${latest.p + 1}`;
+    const go = h('a', { class: 'btn primary', href: readUrl(D.manga.id, latest.continue.c, latest.continue.v, latest.t) }, latest.continue.text);
+    const stay = h('button', { class: 'btn', type: 'button' }, 'Keep reading here');
+    stay.onclick = () => {
+      staleCard.remove(); staleCard = null; stale = null;
+      markSeen(latest.t);
+      saveProgress();
+      stage.focus({ preventScroll: true });
+    };
+    staleCard = h('div', { class: 'stale-session', role: 'dialog', 'aria-modal': 'true', 'aria-labelledby': 'stale-title' },
+      h('div', { class: 'stale-box' },
+        h('h2', { id: 'stale-title' }, 'You have read further since'),
+        h('p', {}, 'This page is an older reading session. Your newest reading position is ', h('b', {}, where), ` (${ago(latest.t)}).`),
+        h('div', { class: 'stale-actions' }, go, stay),
+        h('p', { class: 'muted small' }, `Keeping ${D.chapter.label} makes it your “Continue” point again.`)));
+    document.body.append(staleCard);
+    go.focus();
+  }
+  async function recheck() {
+    if (stale || document.hidden) return;
+    try { checkLatest((await api('api/progress/latest?' + qsa({ m: D.manga.id }))).latest); } catch { /* offline: the next save checks again */ }
+  }
+  document.addEventListener('visibilitychange', recheck);
+  window.addEventListener('pageshow', e => { if (e.persisted) recheck(); });
+
  // Book mode: pages pair up inside each run of single pages. Runs restart after every double page / cover,
  // so one missing pair never shifts the rest of the chapter. "Shift" makes a run start with a lone page.
  function computeSpreads() {
@@ -240,7 +289,7 @@
    const n = D.next;
    return h('div', { class: 'end' }, h('div', { class: 'endbox' },
      h('div', { class: 'muted' }, 'End of ' + D.chapter.label + (D.chapter.title ? ' · ' + D.chapter.title : '')),
-      n ? h('a', { class: 'btn primary', href: readUrl(D.manga.id, n.id), onclick: () => saveProgress(true) }, `Next: ${n.label}${n.title ? ' · ' + n.title : ''} ›`)
+      n ? h('a', { class: 'btn primary', href: chapterUrl(n.id), onclick: e => { e.currentTarget.href = chapterUrl(n.id); saveProgress(true); } }, `Next: ${n.label}${n.title ? ' · ' + n.title : ''} ›`)
        : h('div', {}, 'You are up to date.'),
      h('a', { class: 'btn', href: mangaUrl(D.manga.id) }, 'Back to ' + D.manga.title)));
  }
@@ -589,7 +638,7 @@
  function goChapter(c) {
    if (!c) return toast('You are up to date');
    saveProgress(true);
-    location.href = readUrl(D.manga.id, c.id);
+    location.href = chapterUrl(c.id);
  }
  // Flow: jump to the top of the next page, but never further than ~one screen.
  function flowStep(dir) {
@@ -701,8 +750,13 @@
  }
  function saveProgress(keepalive) {
    clearTimeout(saveTimer);
-    const body = JSON.stringify({ m: D.manga.id, c: D.chapter.id, v: D.version, p: list[cur].i, n: all.length, done, shift: [...shift] });
-    fetch('api/progress', { method: 'POST', keepalive: !!keepalive, headers: { 'Content-Type': 'application/json' }, body }).catch(() => {});
+    if (stale) return; // nothing is saved until the reader chose where to go on
+    const body = JSON.stringify({ m: D.manga.id, c: D.chapter.id, v: D.version, p: list[cur].i, n: all.length, done, shift: [...shift], tab, seen });
+    fetch('api/progress', { method: 'POST', keepalive: !!keepalive, headers: { 'Content-Type': 'application/json' }, body })
+      .then(r => r.json()).then(r => {
+        if (r.stale) checkLatest(r.latest);
+        else if (r.ok && r.t) markSeen(r.t);
+      }).catch(() => {});
  }
  addEventListener('pagehide', () => saveProgress(true));

@@ -717,17 +771,17 @@
    groups[c.book].append(h('option', { value: c.id }, `${c.label}${c.title ? ' · ' + c.title : ''}${c.extra ? ' (extra)' : ''}${c.done ? ' ✓' : ''}`));
  }
  chsel.value = D.chapter.id;
-  chsel.onchange = () => { saveProgress(true); location.href = readUrl(D.manga.id, chsel.value); };
+  chsel.onchange = () => { saveProgress(true); location.href = chapterUrl(chsel.value); };
  $('#back').href = mangaUrl(D.manga.id);
  for (const [id, c] of [['#prevch', D.prev], ['#nextch', D.next]]) {
    const a = $(id);
-    if (c) { a.href = readUrl(D.manga.id, c.id); a.title = c.label + (c.title ? ' · ' + c.title : ''); a.onclick = () => saveProgress(true); }
+    if (c) { a.href = chapterUrl(c.id); a.title = c.label + (c.title ? ' · ' + c.title : ''); a.onclick = () => { a.href = chapterUrl(c.id); saveProgress(true); }; }
    else a.classList.add('disabled');
  }
  for (const v of D.versions) ver.append(h('option', { value: v.id }, (v.source || v.id) + (v.score ? ` (${v.score > 0 ? '+' : ''}${v.score})` : '')));
  ver.value = D.version;
  ver.hidden = D.versions.length < 2;
-  ver.onchange = () => { saveProgress(true); location.href = readUrl(D.manga.id, D.chapter.id, ver.value); };
+  ver.onchange = () => { saveProgress(true); location.href = chapterUrl(D.chapter.id, ver.value); };
  for (const b of modeBtns) b.onclick = () => { if (b.dataset.mode !== mode) setMode(b.dataset.mode, true); };
  toneButton.onclick = cycleTone;
  $('#moment').onclick = saveMoment;
@@ -748,6 +802,7 @@
  for (const bar of [$('#top'), $('#bot')]) bar.addEventListener('click', e => { if (e.target.closest('button')) stage.focus({ preventScroll: true }); });

  setMode(mode, false);
+  if (newer(D.latest)) checkLatest(D.latest); else markSeen(seen);
  if (S.readingClock) readingClock = createReadingClock({
    button: $('#readclock'),
    panel: $('#clockpanel'),
@@ -15,15 +15,68 @@
  const saved = h('span', { class: 'saved', hidden: true }, 'Saved');
  shell.titleRow.append(saved);
  let savedTimer = 0;
+  let refreshSessions = () => {};
  async function save(patch) {
    Object.assign(S, (await api('api/settings', patch)).settings);
    saved.hidden = false;
    clearTimeout(savedTimer);
    savedTimer = setTimeout(() => { saved.hidden = true; }, 1500);
+    refreshSessions();
+  }
+
+  // Which login session holds which reader settings (reader-sessions.js on the server).
+  function readerSessionsCard() {
+    const TONE = { original: 'Original', inverted: 'Inverted', sepia: 'Sepia', dim: 'Dim', 'extra-dim': 'Extra dim' };
+    const START = { last: 'last mode', flow: 'always Flow', page: 'always Page', book: 'always Book' };
+    const summary = r => [`${LABEL[r.lastMode] || r.lastMode} (opens: ${START[r.startMode] || r.startMode})`, `tone ${TONE[r.pageTone] || r.pageTone}`,
+      'zoom ' + (Object.keys(r.zoom || {}).length ? Object.entries(r.zoom).map(([k, z]) => `${LABEL[k] || k} ${Math.round(z * 100)}%`).join(', ') : 'fit'),
+      r.skipExtras ? 'skips extras' : null, r.skipCovers ? 'skips covers' : null, r.flowPageGap === false ? 'no Flow gap' : null].filter(Boolean).join(' · ');
+    const state = h('div', {}, h('p', { class: 'muted' }, 'Loading sessions…'));
+    const message = h('span', { class: 'small' });
+    async function act(id, action, current) {
+      try {
+        draw(await api('api/reader-sessions', { id, action }));
+        // This page's controls show this session's settings; reload them when they changed.
+        if (current && action === 'follow') location.reload();
+      } catch (error) { message.textContent = error.message; message.className = 'small error'; }
+    }
+    function draw(o) {
+      const current = o.sessions.find(s => s.current), source = o.sessions.find(s => s.id === o.latestFrom);
+      const latestText = !o.latestFrom ? 'one shared set (changed while per-session settings were off, or never changed)'
+        : source ? (source.current ? 'this session' : `${source.device}, active ${ago(source.seen)}`) : 'a session that has since signed out';
+      const intent = !o.enabled ? 'Off: every session uses the same reader settings, and a change applies everywhere.'
+        : current?.locked ? 'This session has its own reader settings. Changes here stay here and become the starting point for new sessions.'
+        : 'This session follows the latest reader settings. Your first change here gives it its own copy, which stays put when other sessions change theirs.';
+      state.replaceChildren(
+        h('p', {}, h('b', {}, 'Now: '), intent),
+        o.enabled ? h('p', { class: 'muted small' }, 'New sessions start from the latest settings: ', h('b', {}, summary(o.latest)), ` — from ${latestText}.`)
+          : h('p', { class: 'muted small' }, 'Shared settings: ', h('b', {}, summary(o.latest))),
+        h('ul', { class: 'reader-sessions' }, o.sessions.map(s => h('li', {},
+          h('div', {}, h('b', {}, s.device), s.current ? ' (this session)' : '', ' · ',
+            h('span', { class: 'muted small' }, `signed in ${new Date(s.created).toLocaleDateString()}, active ${ago(s.seen)}`)),
+          h('div', { class: 'small' }, !o.enabled ? 'Uses the shared settings' + (s.locked ? ' (its own copy is kept for when this is on again)' : '')
+            : s.locked ? 'Own settings: ' + summary(s.reader) : 'Follows the latest settings'),
+          o.enabled ? h('div', { class: 'row' },
+            s.locked ? h('button', { class: 'btn small', onclick: () => act(s.id, 'follow', s.current) }, 'Follow latest again') : null,
+            s.locked && s.id !== o.latestFrom ? h('button', { class: 'btn small', onclick: () => act(s.id, 'latest', s.current) }, 'Use for new sessions') : null) : null))),
+        message);
+    }
+    refreshSessions = () => api('api/reader-sessions').then(draw, error => { message.textContent = error.message; message.className = 'small error'; });
+    refreshSessions();
+    return h('section', { class: 'card' },
+      h('h2', {}, 'Reader settings per session'),
+      // The controls above switch between this session's set and the shared one, so reload them.
+      h('label', { class: 'check' },
+        h('input', { type: 'checkbox', checked: !!S.readerPerSession, onchange: async e => { await save({ readerPerSession: e.target.checked }); location.reload(); } }),
+        h('span', {}, 'Keep reader settings per session', h('div', { class: 'muted small' }, 'Each sign-in (device or browser) keeps its own reader mode, zoom, tone and the other reader preferences above once you change one there. A new sign-in copies the settings of the session you used last. Turn this off for one shared set.'))),
+      state);
  }
  const check = (key, text, hint) => h('label', { class: 'check' },
    h('input', { type: 'checkbox', checked: !!S[key], onchange: e => save({ [key]: e.target.checked }) }),
    h('span', {}, text, hint ? h('div', { class: 'muted small' }, hint) : null));
+  const number = (key, text, max) => h('label', { class: 'field' }, h('span', {}, text),
+    h('input', { type: 'number', min: 0, max, step: 1, value: S[key], style: 'width:6em',
+      onchange: e => { const n = Math.round(+e.target.value); if (n >= 0 && n <= max) save({ [key]: n }); else e.target.value = S[key]; } }));

  const startMode = h('select', { onchange: e => save({ startMode: e.target.value }) },
    h('option', { value: 'last' }, 'The mode I used last'),
@@ -90,10 +143,15 @@
      h('button', { class: 'btn small', onclick: async () => { await save({ zoom: {} }); zoomText.textContent = zooms(); } }, 'Reset to fit'),
      h('div', { class: 'muted small' }, '100% = the page fits the screen. Change it in the reader with Ctrl + mouse wheel, a pinch, or the + / - keys.'))));

+  section('user/reading').append(readerSessionsCard());
+
  section('user/reading').append(h('section', { class: 'card' },
    h('h2', {}, 'Library page'),
    check('continueRow', 'Show "Continue where you left off" at the top',
-      'One row with the five manga you read most recently and have not finished. It hides itself while you search, filter by status, or sort by "Recently read".')));
+      'One row with the five manga you read most recently that still have chapters left after the last one you read. It hides itself while you search, filter by status, or sort by "Recently read".'),
+    h('p', { class: 'muted small' }, 'Rereading: later chapters you finished in an earlier pass count as left again when either rule applies. 0 turns a rule off.'),
+    number('rereadDays', 'Finished more than this many days before my last read', 3650),
+    number('rereadChapters', 'Or I have since read more than this many chapters in a row', 1000)));

  section('user/reading').append(h('section', { class: 'card' },
    h('h2', {}, 'Chapter list dates'),
@@ -0,0 +1,88 @@
+'use strict';
+/* Reader settings per login session (docs/architecture.md, "Reader settings per session").
+ *
+ * The user's own reader settings (`user.settings`) are the "latest" set. A session that never changed a
+ * reader setting follows the latest set; the first change copies the latest set into the session and
+ * locks it there, and also makes it the new latest set. Using a locked session makes its set the latest
+ * again, so a new login starts from the last active session. With `readerPerSession: false` there is
+ * one set per user, as before; locked sets are kept and return when the switch is turned on again. */
+const crypto = require('crypto');
+
+const READER_KEYS = ['startMode', 'lastMode', 'adapt', 'skipExtras', 'skipCovers', 'flowPageGap', 'pageTone', 'zoom'];
+
+const perSession = settings => settings.readerPerSession !== false;
+const publicId = key => crypto.createHash('sha256').update('reader-session:' + key).digest('hex').slice(0, 16);
+
+function pick(settings) {
+  const out = {};
+  for (const k of READER_KEYS) if (settings[k] !== undefined) out[k] = k === 'zoom' ? { ...settings[k] } : settings[k];
+  return out;
+}
+
+// `base` is the user's merged settings (defaults + user.settings); the session's locked set wins over it.
+function effective(base, session) {
+  if (!perSession(base) || !session?.reader) return base;
+  return { ...base, ...pick(session.reader), zoom: { ...session.reader.zoom } };
+}
+
+// Splits a validated settings patch: reader keys go to the session (locking it) and to the latest set.
+function applyPatch({ user, base, session, key, patch }) {
+  const s = (user.settings = user.settings || {});
+  const reader = pick(patch), rest = Object.fromEntries(Object.entries(patch).filter(([k]) => !READER_KEYS.includes(k)));
+  Object.assign(s, rest);
+  if (!Object.keys(reader).length) return;
+  if (perSession({ ...base, ...rest }) && session) {
+    session.reader = { ...pick(effective(base, session)), ...reader };
+    Object.assign(s, pick(session.reader));
+    user.readerFrom = publicId(key);
+  } else {
+    Object.assign(s, reader);
+    user.readerFrom = null;
+  }
+}
+
+// A request from a locked session makes its set the latest one. Returns true when something changed.
+function noteActive(user, base, session, key) {
+  if (!perSession(base) || !session?.reader) return false;
+  const id = publicId(key);
+  if (user.readerFrom === id) return false;
+  user.settings = { ...(user.settings || {}), ...pick(session.reader) };
+  user.readerFrom = id;
+  return true;
+}
+
+function deviceLabel(agent) {
+  const a = String(agent || '');
+  if (!a) return 'Unknown device';
+  const os = /iPhone/.test(a) ? 'iPhone' : /iPad/.test(a) ? 'iPad' : /Android/.test(a) ? 'Android'
+    : /Windows/.test(a) ? 'Windows' : /Mac OS X|Macintosh/.test(a) ? 'Mac' : /CrOS/.test(a) ? 'ChromeOS' : /Linux/.test(a) ? 'Linux' : '';
+  const browser = /Edg\//.test(a) ? 'Edge' : /OPR\//.test(a) ? 'Opera' : /Firefox\//.test(a) ? 'Firefox'
+    : /Chrome\//.test(a) ? 'Chrome' : /Safari\//.test(a) ? 'Safari' : '';
+  return [browser, os].filter(Boolean).join(' on ') || a.slice(0, 60);
+}
+
+// What Settings shows: every login session of the user with its state and effective reader set.
+function overview(user, base, sessions, currentKey) {
+  const list = Object.entries(sessions).filter(([, s]) => s.u === user.name).map(([key, s]) => ({
+    id: publicId(key), device: deviceLabel(s.agent), created: s.t, seen: s.seen || s.t,
+    current: key === currentKey, locked: !!s.reader, reader: pick(effective(base, s)),
+  })).sort((a, b) => b.current - a.current || b.seen - a.seen);
+  return { enabled: perSession(base), current: currentKey ? publicId(currentKey) : null,
+    latestFrom: user.readerFrom || null, latest: pick(base), sessions: list };
+}
+
+// Settings actions on one of the user's sessions: 'follow' drops its lock, 'latest' makes its set the latest.
+function act(user, base, sessions, id, action) {
+  const entry = Object.entries(sessions).find(([key, s]) => s.u === user.name && publicId(key) === id);
+  if (!entry) return false;
+  const [key, session] = entry;
+  if (action === 'follow') { delete session.reader; if (user.readerFrom === id) user.readerFrom = null; return true; }
+  if (action === 'latest') {
+    user.settings = { ...(user.settings || {}), ...pick(effective(base, session)) };
+    user.readerFrom = session.reader ? publicId(key) : null;
+    return true;
+  }
+  return false;
+}
+
+module.exports = { READER_KEYS, publicId, pick, effective, applyPatch, noteActive, deviceLabel, overview, act };
@@ -40,6 +40,7 @@ const { BackupService, BackupError } = require('./backup');
 const moments = require('./moments');
 const { Tracer, requestTrace } = require('./perf/trace');
 const { ReadAhead } = require('./perf/read-ahead');
+const readerSessions = require('./reader-sessions');

 const PORT = +process.env.PORT || 8080;
 const LIB = path.resolve(process.env.LIBRARY || 'library');
@@ -119,8 +120,10 @@ function checkPw(pw, stored) {
 }
 const DUMMY_HASH = hashPw('x');
 const DEFAULTS = { startMode: 'last', lastMode: 'page', adapt: true, skipExtras: false, skipCovers: false, flowPageGap: true, pageTone: 'original', readingClock: false, readingStory: true,
-  continueRow: true, readDate: 'hour', releaseDate: true, discoveryEnabled: false, discoveryReadingActivity: false, discoveryMature: false, zoom: {}, webhook: '' };
-const settingsOf = u => ({ ...DEFAULTS, ...u.settings, zoom: { ...(u.settings && u.settings.zoom) } });
+  continueRow: true, rereadDays: 7, rereadChapters: 5, readDate: 'hour', releaseDate: true, discoveryEnabled: false, discoveryReadingActivity: false, discoveryMature: false, zoom: {}, webhook: '', readerPerSession: true };
+const userSettingsOf = u => ({ ...DEFAULTS, ...u.settings, zoom: { ...(u.settings && u.settings.zoom) } });
+// With a login session, its locked reader settings (reader-sessions.js) win over the user's latest set.
+const settingsOf = (u, sess) => readerSessions.effective(userSettingsOf(u), sess);

 function createUser(name, pw, admin, replace) {
  name = String(name || '').trim().toLowerCase(); pw = String(pw || '');
@@ -132,13 +135,21 @@ function createUser(name, pw, admin, replace) {
  save();
  return db.users[name];
 }
-function startSession(res, user) {
+function startSession(req, res, user) {
  const token = crypto.randomBytes(32).toString('base64url');
-  db.sessions[sha(token)] = { u: user.name, t: Date.now() };
+  db.sessions[sha(token)] = { u: user.name, t: Date.now(), agent: String(req.headers['user-agent'] || '').slice(0, 300) };
  save();
  res.setHeader('Set-Cookie', `sid=${token}; Path=/; HttpOnly; SameSite=Lax; Max-Age=31536000${SECURE_COOKIE ? '; Secure' : ''}`);
 }
 const tokenOf = req => { const m = /(?:^|;\s*)sid=([^;]+)/.exec(req.headers.cookie || ''); return m ? m[1] : null; };
+function sessionKeyOf(req) { const t = tokenOf(req); return t ? sha(t) : null; }
+// Last-seen time (coarse, to keep db.json writes rare) and device label of a login session.
+function touchSession(u, sess, key, req) {
+  let changed = false;
+  if (!sess.agent && req.headers['user-agent']) { sess.agent = String(req.headers['user-agent']).slice(0, 300); changed = true; }
+  if (Date.now() - (sess.seen || 0) > 5 * 60e3) { sess.seen = Date.now(); changed = true; }
+  if (changed) save();
+}
 function userOf(req) { const t = tokenOf(req), s = t && db.sessions[sha(t)]; return (s && db.users[s.u]) || null; }
 for (const [k, s] of Object.entries(db.sessions)) if (Date.now() - s.t > 365 * 864e5 || !db.users[s.u]) delete db.sessions[k];

@@ -438,14 +449,47 @@ function readAtOf(progress, record) {
  if (progress.doneAt) return { at: progress.doneAt, approx: false };
  return earliestCompletion(record);
 }
-function continueOf(m, prog, s) {
-  const ok = c => !(s.skipExtras && c.extra);
+// The most recently saved chapter position of a manga: the head that "Continue" follows.
+function lastOf(m, prog) {
  let last = null;
  for (const ch of m.chapters) { const p = prog[ch.id]; if (p && (!last || p.t > last.p.t)) last = { ch, p }; }
-  if (!last) { const first = m.chapters.find(ok) || m.chapters[0]; return { c: first.id, text: 'Start reading · ' + first.label }; }
-  if (!last.p.done) return { c: last.ch.id, v: last.p.v, text: `Continue · ${last.ch.label} · page ${last.p.p + 1}` };
+  return last;
+}
+// `at` is the head's time; reader links carry it so a reader opened from a stale page notices a newer head.
+function continueOf(m, prog, s) {
+  const ok = c => !(s.skipExtras && c.extra);
+  const last = lastOf(m, prog);
+  if (!last) { const first = m.chapters.find(ok) || m.chapters[0]; return { c: first.id, at: 0, text: 'Start reading · ' + first.label }; }
+  const at = last.p.t;
+  if (!last.p.done) return { c: last.ch.id, v: last.p.v, at, text: `Continue · ${last.ch.label} · page ${last.p.p + 1}` };
  const next = m.chapters.slice(m.chapters.indexOf(last.ch) + 1).find(ok);
-  return next ? { c: next.id, text: 'Read next · ' + next.label } : { c: last.ch.id, v: last.p.v, text: 'Read again · ' + last.ch.label };
+  return next ? { c: next.id, at, text: 'Read next · ' + next.label } : { c: last.ch.id, v: last.p.v, at, text: 'Read again · ' + last.ch.label };
+}
+// Chapters still ahead of the head: never finished, or last read in an earlier pass. 0 = caught up.
+// A done chapter after the head belongs to an earlier pass (the head is a reread) when it was saved
+// more than `rereadDays` before the head, or before a run of more than `rereadChapters` chapters read
+// in order up to the head. 0 turns either rule off.
+function leftOf(m, prog, s) {
+  const last = lastOf(m, prog);
+  if (!last) return 0;
+  const chapters = m.chapters.filter(c => c === last.ch || !(s.skipExtras && c.extra)), at = chapters.indexOf(last.ch);
+  let runStart = last.p.t, run = 1;
+  for (let i = at - 1; i >= 0; i--) {
+    const p = prog[chapters[i].id];
+    if (!p || !p.done || p.t > runStart) break;
+    runStart = p.t; run++;
+  }
+  const gap = s.rereadDays > 0 ? s.rereadDays * 24 * 3600 * 1000 : Infinity;
+  const passStart = s.rereadChapters > 0 && run > s.rereadChapters ? runStart : -Infinity;
+  return chapters.slice(at + 1).filter(c => { const p = prog[c.id]; return !p || !p.done || last.p.t - p.t > gap || p.t < passStart; }).length
+    + (last.p.done ? 0 : 1);
+}
+// What a reader tab compares itself with (stale reading sessions, docs/architecture.md).
+function latestOf(m, prog, s) {
+  const last = lastOf(m, prog);
+  if (!last) return null;
+  const { t, w, v, p, n, done } = last.p;
+  return { t, w: w || '', c: last.ch.id, label: last.ch.label, v, p, n, done, continue: continueOf(m, prog, s) };
 }
 // From the saved page on, then the pages before it; afterwards the next chapter's preferred version.
 function warmChapter(u, m, ch, v, progress, s) {
@@ -471,11 +515,11 @@ const PUBLIC = new Set(['/api/auth', '/api/login', '/api/signup']);
 const routes = {
  'GET /api/health': () => ({ ok: !scanState.error, service: 'reader', uptime: Math.round(process.uptime()), scan: scanState }),
  'GET /api/collections': ({ u }) => ({ collections: routes['GET /api/library']({ u }).collections }),
-  'GET /api/collection': ({ u, q }) => {
+  'GET /api/collection': ({ u, q, sess }) => {
    const view = routes['GET /api/library']({ u }).collections.find(c => c.id === q.get('id')) || bad(404, 'Collection not found');
    const next = view.members.find(m => m.read < m.chapters) || view.members[0];
    const manga = mangaOf(next.id);
-    return { ...view, continue: { m: next.id, ...continueOf(manga, progressOf(u, manga), settingsOf(u)) },
+    return { ...view, continue: { m: next.id, ...continueOf(manga, progressOf(u, manga), settingsOf(u, sess)) },
      relations: catalog.state.relations.filter(r => r.state === 'confirmed' && view.members.some(m => m.id === r.from || m.id === r.to)) };
  },
  'GET /api/admin/catalog': ({ u }) => { admin(u); return { ...catalog.state, types: TYPES, roles: ROLES, mangas: lib.mangas.map(m => ({ id: m.id, title: m.title })) }; },
@@ -523,16 +567,16 @@ const routes = {
  },
  'GET /api/auth': () => ({ firstRun: !Object.keys(db.users).length, signup: OPEN_SIGNUP }),

-  'POST /api/signup': ({ b, res }) => {
+  'POST /api/signup': ({ req, b, res }) => {
    const first = !Object.keys(db.users).length;
    if (!first && !OPEN_SIGNUP) bad(403, 'Sign-up is closed. Ask an admin for an account.');
-    startSession(res, createUser(b.name, b.password, first));
+    startSession(req, res, createUser(b.name, b.password, first));
    return { ok: true };
  },
-  'POST /api/login': ({ b, res }) => {
+  'POST /api/login': ({ req, b, res }) => {
    const user = db.users[String(b.name || '').trim().toLowerCase()], pw = String(b.password || '');
    if (!checkPw(pw, user ? user.hash : DUMMY_HASH) || !user) bad(403, 'Wrong user name or password.');
-    startSession(res, user);
+    startSession(req, res, user);
    return { ok: true };
  },
  'POST /api/logout': ({ req, res }) => {
@@ -541,7 +585,18 @@ const routes = {
    res.setHeader('Set-Cookie', 'sid=; Path=/; HttpOnly; SameSite=Lax; Max-Age=0');
    return { ok: true };
  },
-  'GET /api/me': ({ u }) => ({ name: u.name, admin: !!u.admin, settings: settingsOf(u), unread: unreadOf(u) }),
+  // Every page loads /api/me, so a page view marks its session as the last active one for reader settings.
+  'GET /api/me': ({ u, sess, sk }) => {
+    if (sess && readerSessions.noteActive(u, userSettingsOf(u), sess, sk)) save();
+    return { name: u.name, admin: !!u.admin, settings: settingsOf(u, sess), unread: unreadOf(u) };
+  },
+  'GET /api/reader-sessions': ({ u, sk }) => readerSessions.overview(u, userSettingsOf(u), db.sessions, sk),
+  'POST /api/reader-sessions': ({ u, b, sk }) => {
+    if (!['follow', 'latest'].includes(b.action)) bad(400, 'Unknown action');
+    if (!readerSessions.act(u, userSettingsOf(u), db.sessions, String(b.id || ''), b.action)) bad(404, 'Session not found');
+    save();
+    return readerSessions.overview(u, userSettingsOf(u), db.sessions, sk);
+  },

  'GET /api/reading-schedule': () => publicSchedule(readingSchedule),
  'GET /api/reading-access': ({ u, q }) => { mangaOf(q.get('m')); return readingAccess.status(u.name, true); },
@@ -558,22 +613,25 @@ const routes = {
    return { ok: true };
  },

-  'POST /api/settings': ({ u, b }) => {
+  'POST /api/settings': ({ u, b, sess, sk }) => {
    if (typeof b.webhook === 'string' && b.webhook.trim() && !/^https?:\/\/\S+$/i.test(b.webhook.trim())) bad(400, 'The webhook must be an http(s) URL.');
-    const s = (u.settings = u.settings || {});
+    const base = userSettingsOf(u), s = {};
    if (['last', 'flow', 'page', 'book'].includes(b.startMode)) s.startMode = b.startMode;
    if (['flow', 'page', 'book'].includes(b.lastMode)) s.lastMode = b.lastMode;
    if (['original', 'inverted', 'sepia', 'dim', 'extra-dim'].includes(b.pageTone)) s.pageTone = b.pageTone;
    if (['off', 'date', 'hour'].includes(b.readDate)) s.readDate = b.readDate;
+    if (Number.isInteger(b.rereadDays) && b.rereadDays >= 0 && b.rereadDays <= 3650) s.rereadDays = b.rereadDays;
+    if (Number.isInteger(b.rereadChapters) && b.rereadChapters >= 0 && b.rereadChapters <= 1000) s.rereadChapters = b.rereadChapters;
    for (const k of ['adapt', 'skipExtras', 'skipCovers', 'flowPageGap', 'readingClock', 'readingStory', 'releaseDate', 'continueRow',
-      'discoveryEnabled', 'discoveryReadingActivity', 'discoveryMature']) if (typeof b[k] === 'boolean') s[k] = b[k];
+      'discoveryEnabled', 'discoveryReadingActivity', 'discoveryMature', 'readerPerSession']) if (typeof b[k] === 'boolean') s[k] = b[k];
    if (b.zoom && typeof b.zoom === 'object') {
      s.zoom = {};
      for (const k of ['flow', 'page', 'book', 'strip']) if (+b.zoom[k] > 0) s.zoom[k] = Math.min(8, Math.max(0.1, +b.zoom[k]));
    }
    if (typeof b.webhook === 'string') s.webhook = b.webhook.trim().slice(0, 500);
+    readerSessions.applyPatch({ user: u, base, session: sess, key: sk, patch: s });
    save();
-    return { settings: settingsOf(u) };
+    return { settings: settingsOf(u, sess) };
  },
  'POST /api/password': ({ u, b }) => {
    if (!checkPw(String(b.old || ''), u.hash)) bad(403, 'The current password is wrong.');
@@ -583,7 +641,7 @@ const routes = {

  'GET /api/library': ({ u }) => {
    const prog = db.progress[u.name] || {}, fol = db.follows[u.name] || {}, notes = (db.notes[u.name] || []).filter(n => !n.read);
-    const showStory = settingsOf(u).readingStory;
+    const s = settingsOf(u), showStory = s.readingStory;
    const mangas = lib.mangas.map(m => {
      const p = prog[m.id] || {}, meta = m.meta || {}, release = firstReleaseOf(meta);
      return {
@@ -593,7 +651,7 @@ const routes = {
        tags: Array.isArray(meta.tags) ? meta.tags : (meta.tags ? [String(meta.tags)] : []), status: meta.status || '', year: meta.year || '',
        firstRelease: release.label, firstReleaseAt: release.time,
        read: m.chapters.filter(c => p[c.id] && p[c.id].done).length,
-        lastRead: Object.values(p).reduce((t, x) => Math.max(t, x.t || 0), 0),
+        lastRead: Object.values(p).reduce((t, x) => Math.max(t, x.t || 0), 0), left: leftOf(m, p, s),
        following: !!fol[m.id], unread: notes.filter(n => n.m === m.id).length,
        reading: showStory ? mangaInsight(mangaReadingOf(u, m), m.chapters.map(ch => ch.id)) : null,
      };
@@ -701,8 +759,8 @@ const routes = {
    return { results: await searchGreatestMangaDex(entry) };
  },

-  'GET /api/manga': ({ u, q }) => {
-    const m = mangaOf(q.get('m')), prog = progressOf(u, m), s = settingsOf(u), showStory = s.readingStory;
+  'GET /api/manga': ({ u, q, sess }) => {
+    const m = mangaOf(q.get('m')), prog = progressOf(u, m), s = settingsOf(u, sess), showStory = s.readingStory;
    const records = mangaReadingOf(u, m);
    return {
      chapterDates: { read: s.readDate, release: s.releaseDate },
@@ -719,7 +777,7 @@ const routes = {
        dates: s.releaseDate ? chapterDates(ch.versions) : null,
      })),
      reading: showStory ? mangaInsight(records, m.chapters.map(ch => ch.id)) : null,
-      continue: continueOf(m, prog, settingsOf(u)),
+      continue: continueOf(m, prog, s),
    };
  },

@@ -760,8 +818,8 @@ const routes = {
    return { ok: true, deleted: m.id };
  },

-  'GET /api/chapter': ({ u, q }) => {
-    const m = mangaOf(q.get('m')), ch = chapterOf(m, q.get('c')), s = settingsOf(u), prog = progressOf(u, m);
+  'GET /api/chapter': ({ u, q, sess }) => {
+    const m = mangaOf(q.get('m')), ch = chapterOf(m, q.get('c')), s = settingsOf(u, sess), prog = progressOf(u, m);
    if (!readingAccess.status(u.name).allowed) bad(423, 'Reading is outside the deployment schedule. Complete the five-question challenge to unlock it.');
    const v = ch.versions.find(x => x.id === q.get('v')) || ranked(m, ch)[0].v;
    // Opening a chapter clears its "new chapter" notification.
@@ -777,6 +835,7 @@ const routes = {
      pages: v.pages.map(p => ({ u: url(v.rel + '/' + p.f), w: p.w, h: p.h, t: p.t, r: p.r })),
      prev: neighbour(m, ch, -1, s), next: neighbour(m, ch, 1, s),
      progress: prog[ch.id] || null,
+      latest: latestOf(m, prog, s),
      reading: s.readingClock ? publicSummary(readingOf(u, m, ch), v.id, eligiblePages(v, s)) : null,
      // the user's moments on this version, so the reader can mark pages that already have one
      moments: momentsOf(u).filter(x => x.m === m.id && x.c === ch.id && x.v === v.id)
@@ -787,18 +846,30 @@ const routes = {
    };
  },

+  'GET /api/progress/latest': ({ u, q }) => {
+    const m = mangaOf(q.get('m'));
+    return { latest: latestOf(m, progressOf(u, m), settingsOf(u)) };
+  },
  'POST /api/progress': ({ u, b }) => {
    const m = mangaOf(b.m), ch = chapterOf(m, b.c);
    const all = (db.progress[u.name] = db.progress[u.name] || {}), mp = (all[m.id] = all[m.id] || {}), old = mp[ch.id] || {};
+    const tab = /^[a-zA-Z0-9_-]{8,40}$/.test(String(b.tab || '')) ? String(b.tab) : '';
+    // A reader tab sends the head time it knows (`seen`). When another tab or device saved a newer
+    // position since, this tab is stale: it must not become the head until the reader chooses to stay.
+    if (Number.isFinite(b.seen)) {
+      const last = lastOf(m, mp);
+      if (last && last.p.t > b.seen && (!tab || last.p.w !== tab)) return { ok: false, stale: true, latest: latestOf(m, mp, settingsOf(u)) };
+    }
    const now = Date.now(), done = !!(old.done || b.done);
    // doneAt: when the chapter was first completed; kept until it is marked unread.
    const doneAt = old.done ? old.doneAt : done ? now : undefined;
    mp[ch.id] = {
      v: String(b.v || ''), p: Math.max(0, b.p | 0), n: Math.max(0, b.n | 0), t: now, done, ...(doneAt ? { doneAt } : {}),
      shift: Array.isArray(b.shift) ? b.shift.filter(Number.isInteger).slice(0, 1000) : old.shift || [],
+      ...(tab ? { w: tab } : {}),
    };
    save();
-    return { ok: true };
+    return { ok: true, t: now };
  },
  // Separate endpoint: an older server on rollback cannot misread cumulative
  // visit totals as legacy deltas. Old open tabs retain their original protocol.
@@ -1102,7 +1173,9 @@ async function handleApi(req, res, u, route, q) {
    if (!/^application\/json/.test(req.headers['content-type'] || '') || req.headers['sec-fetch-site'] === 'cross-site') bad(403, 'Bad request origin');
    b = (await readBody(req)) || {};
  }
-  sendJson(res, 200, await route({ req, res, u, b, q }));
+  const sk = u && sessionKeyOf(req), sess = sk && db.sessions[sk];
+  if (sess) touchSession(u, sess, sk, req);
+  sendJson(res, 200, await route({ req, res, u, b, q, sess, sk }));
 }
 function serveFile(req, res, root, rel, cacheControl, only, trace) {
  let file;
@@ -0,0 +1,110 @@
+'use strict';
+// "Continue where you left off" only lists manga with something left after the last chapter read:
+// unread chapters, or chapters last read in an earlier pass (a reread).
+const test = require('node:test'), assert = require('node:assert/strict');
+const fs = require('fs'), os = require('os'), path = require('path'), net = require('net');
+const { spawn } = require('child_process');
+const { Canvas } = require('../tools/png');
+
+async function freePort() {
+  const listener = net.createServer();
+  await new Promise(resolve => listener.listen(0, '127.0.0.1', resolve));
+  const port = listener.address().port;
+  await new Promise(resolve => listener.close(resolve));
+  return port;
+}
+
+async function start(library, data) {
+  const port = await freePort(), output = [];
+  const child = spawn(process.execPath, ['server.js'], { cwd: path.resolve(__dirname, '..'), windowsHide: true,
+    env: { ...process.env, LIBRARY: library, DATA: data, PORT: String(port), SCAN_INTERVAL: '0', FULL_SCAN_INTERVAL: '0',
+      SCRAPER_URL: 'http://127.0.0.1:9', SCRAPER_TOKEN: 'fixture-token', SCRAPER_TOKEN_FILE: '', BACKUP: '', GREATEST_COVER_WARM: '0' } });
+  child.stdout.on('data', d => output.push(String(d)));
+  child.stderr.on('data', d => output.push(String(d)));
+  const base = `http://127.0.0.1:${port}`;
+  let ready = false;
+  for (let n = 0; n < 100 && !ready; n++) {
+    ready = await fetch(base + '/health').then(r => r.ok).catch(() => false);
+    if (!ready) await new Promise(resolve => setTimeout(resolve, 50));
+  }
+  assert.ok(ready, output.join(''));
+  return { child, base };
+}
+async function stop(child) {
+  if (child && child.exitCode === null) { child.kill(); await new Promise(resolve => child.once('exit', resolve)); }
+}
+
+test('the continue row counts chapters left after the head, rereads included', { timeout: 30000 }, async () => {
+  const root = fs.mkdtempSync(path.join(os.tmpdir(), 'mc-left-'));
+  let server;
+  try {
+    const library = path.join(root, 'library'), data = path.join(root, 'data');
+    for (const [title, count] of [['Moon Garden', 4], ['Sun Field', 4], ['Star Path', 8]])
+      for (let n = 1; n <= count; n++) {
+        const dir = path.join(library, title, 'v01', `c00${n}`);
+        fs.mkdirSync(dir, { recursive: true });
+        fs.writeFileSync(path.join(dir, '001.png'), new Canvas(60, 90, [40, 60, 120]).png());
+      }
+    fs.mkdirSync(data);
+    server = await start(library, data);
+    let { base } = server;
+    const post = (cookie, url, body) => fetch(base + url, { method: 'POST',
+      headers: { 'content-type': 'application/json', cookie }, body: JSON.stringify(body) }).then(r => r.json());
+    const get = (cookie, url) => fetch(base + url, { headers: { cookie } }).then(r => r.json());
+    const signup = await fetch(base + '/api/signup', { method: 'POST', headers: { 'content-type': 'application/json' },
+      body: JSON.stringify({ name: 'alice', password: 'alice-password' }) });
+    const alice = signup.headers.get('set-cookie').split(';')[0];
+    await post(alice, '/api/admin/rescan', { full: true });
+    const ids = async m => (await get(alice, '/api/manga?m=' + encodeURIComponent(m))).chapters.map(c => ({ c: c.id, v: c.versions[0].id }));
+    const moon = await ids('Moon Garden'), sun = await ids('Sun Field');
+    const done = (m, ch) => post(alice, '/api/progress', { m, ...ch, p: 0, n: 1, done: true });
+    const left = async () => Object.fromEntries((await get(alice, '/api/library')).mangas.map(m => [m.id, m.left]));
+
+    // First read stopped after chapter 2: two chapters left. Finished: nothing left.
+    for (const ch of moon.slice(0, 2)) await done('Moon Garden', ch);
+    for (const ch of sun) await done('Sun Field', ch);
+    assert.deepEqual(await left(), { 'Moon Garden': 2, 'Sun Field': 0, 'Star Path': 0 });
+
+    // Read all 8 chapters of Star Path, then reread 1-6 right away: more than 5 in a row is a reread
+    // even within the time limit; with a longer run setting, or the run rule off, it is not.
+    const star = await ids('Star Path');
+    for (const ch of star) await done('Star Path', ch);
+    await new Promise(resolve => setTimeout(resolve, 5));
+    for (const ch of star.slice(0, 5)) await done('Star Path', ch);
+    assert.equal((await left())['Star Path'], 0, 'five in a row is not yet a reread');
+    await done('Star Path', star[5]);
+    assert.equal((await left())['Star Path'], 2);
+    await post(alice, '/api/settings', { rereadChapters: 6 });
+    assert.equal((await left())['Star Path'], 0);
+    await post(alice, '/api/settings', { rereadChapters: 0 });
+    assert.equal((await left())['Star Path'], 0);
+    await post(alice, '/api/settings', { rereadChapters: 5, rereadDays: -1 });
+    const settings = (await get(alice, '/api/me')).settings;
+    assert.equal(settings.rereadDays, 7, 'invalid values are ignored');
+    assert.equal((await left())['Star Path'], 2);
+
+    // Unfinished head: the rest of that chapter is still left.
+    await post(alice, '/api/progress', { m: 'Moon Garden', ...moon[2], p: 0, n: 1 });
+    assert.equal((await left())['Moon Garden'], 2);
+
+    // Glancing back at chapter 1 right after finishing is not a reread.
+    await done('Sun Field', sun[0]);
+    assert.equal((await left())['Sun Field'], 0);
+
+    // The finish was a month ago: rereading chapters 1-2 now leaves 3-4 from the earlier pass.
+    await new Promise(resolve => setTimeout(resolve, 700));
+    await stop(server.child);
+    const dbFile = path.join(data, 'db.json'), db = JSON.parse(fs.readFileSync(dbFile, 'utf8'));
+    const month = 30 * 24 * 3600 * 1000, sunProgress = db.progress.alice['Sun Field'];
+    for (const p of Object.values(sunProgress)) { p.t -= month; p.doneAt -= month; }
+    sunProgress[sun[0].c].t += month;
+    fs.writeFileSync(dbFile, JSON.stringify(db));
+    server = await start(library, data);
+    base = server.base;
+    await done('Sun Field', sun[1]);
+    assert.equal((await left())['Sun Field'], 2);
+  } finally {
+    await stop(server && server.child);
+    fs.rmSync(root, { recursive: true, force: true });
+  }
+});
@@ -0,0 +1,106 @@
+'use strict';
+// Reader settings per login session: a session follows the latest set until it changes one, then keeps its own.
+const test = require('node:test'), assert = require('node:assert/strict');
+const fs = require('fs'), os = require('os'), path = require('path'), net = require('net');
+const { spawn } = require('child_process');
+const readerSessions = require('../reader-sessions');
+
+async function freePort() {
+  const listener = net.createServer();
+  await new Promise(resolve => listener.listen(0, '127.0.0.1', resolve));
+  const port = listener.address().port;
+  await new Promise(resolve => listener.close(resolve));
+  return port;
+}
+
+test('device labels name browser and system', () => {
+  assert.equal(readerSessions.deviceLabel('Mozilla/5.0 (iPhone; CPU iPhone OS 17_0 like Mac OS X) AppleWebKit/605.1.15 Version/17.0 Mobile/15E148 Safari/604.1'), 'Safari on iPhone');
+  assert.equal(readerSessions.deviceLabel('Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 Chrome/130.0 Safari/537.36 Edg/130.0'), 'Edge on Windows');
+  assert.equal(readerSessions.deviceLabel(''), 'Unknown device');
+});
+
+test('sessions lock their reader settings on the first change, new ones copy the last active one', { timeout: 20000 }, async () => {
+  const root = fs.mkdtempSync(path.join(os.tmpdir(), 'mc-reader-sessions-'));
+  let child;
+  try {
+    const library = path.join(root, 'library'), data = path.join(root, 'data');
+    fs.mkdirSync(library); fs.mkdirSync(data);
+    const port = await freePort(), output = [];
+    child = spawn(process.execPath, ['server.js'], { cwd: path.resolve(__dirname, '..'), windowsHide: true,
+      env: { ...process.env, LIBRARY: library, DATA: data, PORT: String(port), SCAN_INTERVAL: '0', FULL_SCAN_INTERVAL: '0',
+        SCRAPER_URL: 'http://127.0.0.1:9', SCRAPER_TOKEN: 'fixture-token', SCRAPER_TOKEN_FILE: '', BACKUP: '',
+        GREATEST_COVER_WARM: '0' } });
+    child.stdout.on('data', d => output.push(String(d)));
+    child.stderr.on('data', d => output.push(String(d)));
+    const base = `http://127.0.0.1:${port}`;
+    let ready = false;
+    for (let n = 0; n < 100 && !ready; n++) {
+      ready = await fetch(base + '/health').then(r => r.ok).catch(() => false);
+      if (!ready) await new Promise(resolve => setTimeout(resolve, 50));
+    }
+    assert.ok(ready, output.join(''));
+
+    const json = async r => { const body = await r.json(); assert.equal(r.status, 200, JSON.stringify(body)); return body; };
+    const post = (cookie, url, body) => fetch(base + url, { method: 'POST',
+      headers: { 'content-type': 'application/json', 'user-agent': 'Mozilla/5.0 (X11; Linux x86_64) Firefox/130.0', ...(cookie ? { cookie } : {}) },
+      body: JSON.stringify(body) }).then(async r => (url.endsWith('login') || url.endsWith('signup') ? r : json(r)));
+    const me = async cookie => (await json(await fetch(base + '/api/me', { headers: { cookie } }))).settings;
+    const overview = cookie => fetch(base + '/api/reader-sessions', { headers: { cookie } }).then(json);
+    const login = async () => (await post(null, '/api/login', { name: 'reader', password: 'reader-password' })).headers.get('set-cookie').split(';')[0];
+
+    const a = (await post(null, '/api/signup', { name: 'reader', password: 'reader-password' })).headers.get('set-cookie').split(';')[0];
+    // First session: defaults, following the latest set.
+    assert.equal((await me(a)).lastMode, 'page');
+    assert.equal((await overview(a)).sessions[0].locked, false);
+
+    // Session B exists before A changes anything: it follows A's change.
+    const b = await login();
+    await post(a, '/api/settings', { lastMode: 'flow', zoom: { flow: 1.5 } });
+    assert.equal((await me(b)).lastMode, 'flow');
+    assert.equal((await me(b)).zoom.flow, 1.5);
+
+    // B changes its own: B locks, A keeps its own set.
+    await post(b, '/api/settings', { pageTone: 'sepia' });
+    assert.equal((await me(b)).pageTone, 'sepia');
+    assert.equal((await me(b)).lastMode, 'flow');
+    assert.equal((await me(a)).pageTone, 'original');
+
+    // A non-reader setting is shared and does not lock anything.
+    const c = await login();
+    await post(c, '/api/settings', { continueRow: false });
+    assert.equal((await me(a)).continueRow, false);
+    assert.equal((await overview(c)).sessions.find(s => s.current).locked, false);
+    // C follows the last active session, which is A (it loaded /api/me last).
+    assert.equal((await me(c)).pageTone, 'original');
+    await me(b);
+    assert.equal((await me(c)).pageTone, 'sepia');
+
+    // Overview: three sessions, labels, intent.
+    const o = await overview(a);
+    assert.equal(o.enabled, true);
+    assert.equal(o.sessions.length, 3);
+    assert.equal(o.sessions[0].current, true);
+    assert.equal(o.sessions[0].device, 'Firefox on Linux');
+    assert.deepEqual(o.sessions.map(s => s.locked).sort(), [false, true, true]);
+
+    // "Follow latest again" drops A's lock; "Use for new sessions" makes a set the latest.
+    const idA = o.sessions[0].id, idB = o.sessions.find(s => !s.current && s.locked).id;
+    await post(a, '/api/reader-sessions', { id: idA, action: 'follow' });
+    assert.equal((await me(a)).pageTone, 'sepia');
+    assert.equal((await fetch(base + '/api/reader-sessions', { method: 'POST', headers: { 'content-type': 'application/json', cookie: a },
+      body: JSON.stringify({ id: 'nope', action: 'follow' }) })).status, 404);
+    assert.equal((await post(a, '/api/reader-sessions', { id: idB, action: 'latest' })).latestFrom, idB);
+
+    // Off: one shared set; a change applies everywhere and locks nothing. On again: kept locks return.
+    await post(b, '/api/settings', { readerPerSession: false });
+    await post(a, '/api/settings', { pageTone: 'dim' });
+    assert.equal((await me(b)).pageTone, 'dim');
+    assert.equal((await me(c)).pageTone, 'dim');
+    await post(a, '/api/settings', { readerPerSession: true });
+    assert.equal((await me(b)).pageTone, 'sepia');
+    assert.equal((await me(a)).pageTone, 'sepia');
+  } finally {
+    if (child && child.exitCode === null) { child.kill(); await new Promise(resolve => child.once('exit', resolve)); }
+    fs.rmSync(root, { recursive: true, force: true });
+  }
+});
@@ -0,0 +1,97 @@
+'use strict';
+// Stale reading sessions: a reader tab left open on another device must not move "Continue" back.
+const test = require('node:test'), assert = require('node:assert/strict');
+const fs = require('fs'), os = require('os'), path = require('path'), net = require('net');
+const { spawn } = require('child_process');
+const { Canvas } = require('../tools/png');
+
+async function freePort() {
+  const listener = net.createServer();
+  await new Promise(resolve => listener.listen(0, '127.0.0.1', resolve));
+  const port = listener.address().port;
+  await new Promise(resolve => listener.close(resolve));
+  return port;
+}
+
+test('a save from a tab that missed a newer position is refused until the reader stays', { timeout: 30000 }, async () => {
+  const root = fs.mkdtempSync(path.join(os.tmpdir(), 'mc-stale-'));
+  let child;
+  try {
+    const library = path.join(root, 'library'), data = path.join(root, 'data');
+    for (const ch of ['c001 One', 'c002 Two', 'c003 Three']) {
+      const dir = path.join(library, 'Moon Garden', 'v01', ch);
+      fs.mkdirSync(dir, { recursive: true });
+      for (const n of [1, 2, 3]) fs.writeFileSync(path.join(dir, `00${n}.png`), new Canvas(60, 90, [40 * n, 60, 120]).png());
+    }
+    fs.mkdirSync(data);
+    const port = await freePort(), output = [];
+    child = spawn(process.execPath, ['server.js'], { cwd: path.resolve(__dirname, '..'), windowsHide: true,
+      env: { ...process.env, LIBRARY: library, DATA: data, PORT: String(port), SCAN_INTERVAL: '0', FULL_SCAN_INTERVAL: '0',
+        SCRAPER_URL: 'http://127.0.0.1:9', SCRAPER_TOKEN: 'fixture-token', SCRAPER_TOKEN_FILE: '', BACKUP: '', GREATEST_COVER_WARM: '0' } });
+    child.stdout.on('data', d => output.push(String(d)));
+    child.stderr.on('data', d => output.push(String(d)));
+    const base = `http://127.0.0.1:${port}`;
+    let ready = false;
+    for (let n = 0; n < 100 && !ready; n++) {
+      ready = await fetch(base + '/health').then(r => r.ok).catch(() => false);
+      if (!ready) await new Promise(resolve => setTimeout(resolve, 50));
+    }
+    assert.ok(ready, output.join(''));
+    const post = (cookie, url, body) => fetch(base + url, { method: 'POST',
+      headers: { 'content-type': 'application/json', cookie }, body: JSON.stringify(body) }).then(r => r.json());
+    const get = (cookie, url) => fetch(base + url, { headers: { cookie } }).then(r => r.json());
+    const signup = await fetch(base + '/api/signup', { method: 'POST', headers: { 'content-type': 'application/json' },
+      body: JSON.stringify({ name: 'alice', password: 'alice-password' }) });
+    const alice = signup.headers.get('set-cookie').split(';')[0];
+    await post(alice, '/api/admin/rescan', { full: true });
+
+    const manga = await get(alice, '/api/manga?m=Moon%20Garden');
+    const [one, two, three] = manga.chapters.map(c => ({ c: c.id, v: c.versions[0].id }));
+    const save = (ch, extra) => post(alice, '/api/progress', { m: 'Moon Garden', ...ch, p: 1, n: 3, ...extra });
+    const latest = () => get(alice, '/api/progress/latest?m=Moon%20Garden').then(r => r.latest);
+
+    // Phone reads chapter 1, the tablet then reads on in chapter 3.
+    const first = await save(one, { tab: 'phone-tab-1', seen: 0 });
+    assert.equal(first.ok, true);
+    const phoneSeen = first.t;
+    await new Promise(resolve => setTimeout(resolve, 5));
+    const tablet = await save(three, { tab: 'tablet-tab-1', seen: phoneSeen });
+    assert.equal(tablet.ok, true);
+    assert.equal((await latest()).c, three.c);
+
+    // The phone's old tab wakes up and saves chapter 1 again: refused, the head stays on chapter 3.
+    const refused = await save(one, { tab: 'phone-tab-1', seen: phoneSeen, p: 2 });
+    assert.equal(refused.ok, false);
+    assert.equal(refused.stale, true);
+    assert.equal(refused.latest.c, three.c);
+    assert.equal(refused.latest.w, 'tablet-tab-1');
+    assert.equal(refused.latest.continue.c, three.c);
+    assert.match(refused.latest.continue.text, /Continue/);
+    const after = await get(alice, '/api/manga?m=Moon%20Garden');
+    assert.equal(after.continue.c, three.c);
+    assert.equal(after.continue.at, tablet.t);
+    assert.equal(after.chapters[0].progress.p, 1, 'the stale save changed nothing');
+
+    // The chapter view tells a reader which head it is compared with.
+    const view = await get(alice, `/api/chapter?m=Moon%20Garden&c=${encodeURIComponent(one.c)}`);
+    assert.equal(view.latest.c, three.c);
+    assert.equal(view.latest.t, tablet.t);
+
+    // The tablet's own saves never conflict with themselves, even with an older `seen` still in flight.
+    assert.equal((await save(three, { tab: 'tablet-tab-1', seen: phoneSeen, p: 2 })).ok, true);
+
+    // "Keep reading here": the phone now knows the newest time and its save becomes the head.
+    const head = await latest();
+    const stayed = await save(one, { tab: 'phone-tab-1', seen: head.t, p: 2 });
+    assert.equal(stayed.ok, true);
+    assert.equal((await latest()).c, one.c);
+    assert.equal((await get(alice, '/api/manga?m=Moon%20Garden')).continue.c, one.c);
+
+    // Saves without `seen` (mark as read on the manga page, older clients) behave as before.
+    assert.equal((await save(two, { done: true })).ok, true);
+    assert.equal((await latest()).c, two.c);
+  } finally {
+    if (child && child.exitCode === null) { child.kill(); await new Promise(resolve => child.once('exit', resolve)); }
+    fs.rmSync(root, { recursive: true, force: true });
+  }
+});
Author	SHA1	Message	Date
MaashkinoozheandClaude Opus 5.5	c760141636	Continue row: a run of more than N chapters in order also marks a reread A done chapter after the head now counts as left again when it was finished more than rereadDays before the head (default 7) or before a run of more than rereadChapters chapters read in order up to the head (default 5). Both are user settings under Library page; 0 turns a rule off. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-11-01 11:47:45 +01:00
MaashkinoozheandClaude Opus 5.5	9b529d7709	Continue row: only manga with something left after the last chapter read GET /api/library returns `left` per manga: chapters after the newest saved position that are unfinished, unread, or were last read more than 7 days before it (a reread from the start). The continue row lists manga with left > 0, so caught-up series drop out until a new chapter arrives. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-11-01 11:27:02 +01:00
Maashkinoozhe	dddf9bb4ac	Merge remote-tracking branch 'origin/main' into feature/stale-reading-session	2026-10-31 12:21:24 +01:00
MaashkinoozheandClaude Opus 5.5	618992ec14	Reader: stale reading sessions never move "Continue" back A reader tab left open on one device (or restored by the browser) used to save its old chapter as the newest position as soon as it was shown again. Progress saves now carry the tab id and the newest progress time the tab knows (`seen`); the server refuses a save when another tab or device saved a newer position since. The reader then asks: jump to the newest position, or keep reading here (which makes this chapter the head again). It checks on open, when the tab becomes visible, and on every save. Reader links carry `at` and the reader keeps it in the address bar, so reloads and restored tabs still know what they had seen. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-31 11:49:52 +01:00
MaashkinoozheandClaude Opus 5.5	e3e57b60bd	Reader settings per login session Each sign-in keeps its own reader mode, zoom, page tone and skipping once it changes one; sessions that never changed follow the latest set, and a new sign-in starts from the session used last. Settings -> Reading shows every session's state, lets a session follow the latest again or become the latest, and turns the feature off for one shared set. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-31 11:45:44 +01:00