Chapter dates: read date setting and tiered release dates (BL-0047)

- Chapter rows show when you first finished a chapter (setting: date + hour,
  date, off) from a new durable progress doneAt; older reads fall back to the
  reading clock's earliest remembered completion.
- chapter.json keeps added (arrival in this library, now kept on replace) plus
  x-dates.source (source upload, bulk imports flagged), x-dates.release
  (official, for a later metadata job) and x-dates.ecosystem (first entry into
  any Manga Circus library; carried over peering, earliest wins, clamped).
- Rows show one release date by tier: official > source upload > ecosystem >
  library, with all known dates in the tooltip (setting to hide).
- Fixes: WeebCentral dates came from the chapter page, which has none (every
  chapter got the download time); they now come from the full chapter list.
  MangaDex no longer writes a group's publishAt into added. Peering sends dates.
- tools/backfill-chapter-dates.js migrates an existing library (dry run default).
- Coverage dry run on the server: docs/chapter-dates-coverage-2026-10-24.md.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tools/backfill-chapter-dates.js

@@ -0,0 +1,83 @@
+#!/usr/bin/env node
+'use strict';
+// One-time migration to chapter dates (BL-0047). Dry run by default; apply only with the
+// scraper stopped (--apply --writers-stopped), then run a deep "Rescan" in Settings.
+//  - WeebCentral: x-dates.source from the series' full chapter list (one request per series).
+//  - MangaDex: chapters published before x-dates stored the group's publishAt in "added";
+//    it moves to x-dates.source and "added" becomes the folder's arrival time.
+//  - Every chapter: x-dates.ecosystem = "added" unless an earlier one is already known.
+const fs = require('node:fs').promises;
+const path = require('node:path');
+const { batchFlags, sourceDate, publishedDates } = require('../chapter-dates');
+const weebcentral = require('../scraper/plugins/weebcentral');
+const { writeJsonAtomic } = require('../scraper/lib/publisher');
+
+const args = process.argv.slice(2);
+const apply = args.includes('--apply');
+const only = args.find(arg => arg.startsWith('--manga='))?.slice('--manga='.length);
+const offline = args.includes('--offline');
+const root = args.find(arg => !arg.startsWith('--'));
+if (!root || args.some(arg => arg.startsWith('--') && !['--apply', '--writers-stopped', '--offline'].includes(arg) && !arg.startsWith('--manga='))
+  || (apply && !args.includes('--writers-stopped'))) {
+  console.error('Usage: node tools/backfill-chapter-dates.js <library> [--manga=<folder>] [--offline] [--apply --writers-stopped]');
+  process.exit(2);
+}
+const UA = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/130 Safari/537.36';
+const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));
+const readJson = async file => { try { return JSON.parse(await fs.readFile(file, 'utf8')); } catch { return null; } };
+const dirs = async dir => (await fs.readdir(dir, { withFileTypes: true })).filter(e => e.isDirectory() && !e.name.startsWith('.')).map(e => e.name).sort();
+
+async function weebCentralUploads(seriesId) {
+  const url = `https://weebcentral.com/series/${seriesId}/full-chapter-list`;
+  const response = await fetch(url, { headers: { 'user-agent': UA, accept: 'text/html' }, signal: AbortSignal.timeout(30000) });
+  if (!response.ok) throw new Error(`WeebCentral HTTP ${response.status}`);
+  const { chapters } = weebcentral.catalog({ html: await response.text(), url });
+  return new Map(chapters.filter(c => c.uploadedAt).map(c => [c.id, sourceDate(c.uploadedAt, 'WeebCentral', c.uploadBatch)]));
+}
+
+async function main() {
+  const totals = { chapters: 0, changed: 0, alreadyDated: 0, weebSource: 0, weebBatch: 0, mangaDexMoved: 0, missing: 0 };
+  for (const manga of await dirs(root)) {
+    if (only && manga !== only) continue;
+    const mangaDir = path.join(root, manga), meta = (await readJson(path.join(mangaDir, 'manga.json'))) || {};
+    const versions = [];
+    for (const book of await dirs(mangaDir)) {
+      for (const chapter of await dirs(path.join(mangaDir, book))) {
+        const dir = path.join(mangaDir, book, chapter), file = path.join(dir, 'chapter.json'), chapterMeta = await readJson(file);
+        if (chapterMeta) versions.push({ dir, file, meta: chapterMeta, mtime: (await fs.stat(dir)).mtimeMs });
+      }
+    }
+    let uploads = new Map();
+    const seriesId = meta['x-scraper']?.ids?.weebcentral;
+    if (seriesId && !offline && versions.some(v => /weebcentral\.com\/chapters\//.test(v.meta.source?.url || '') && !v.meta['x-dates'])) {
+      try { uploads = await weebCentralUploads(seriesId); await sleep(2000); }
+      catch (error) { console.warn(`[backfill] ${manga}: WeebCentral list failed: ${error.message}`); }
+    }
+    // Legacy MangaDex "added" values are group upload times; flag bulk uploads among them.
+    const legacyDex = versions.filter(v => !v.meta['x-dates'] && /^MangaDex\b/.test(v.meta.source?.name || '') && Date.parse(v.meta.added));
+    const dexBatch = new Map(batchFlags(legacyDex.map(v => v.meta.added)).map((flag, i) => [legacyDex[i], flag]));
+    let changed = 0;
+    for (const version of versions) {
+      totals.chapters++;
+      if (version.meta['x-dates']) { totals.alreadyDated++; continue; }
+      const prior = { ...version.meta }, incoming = {};
+      const weebId = /weebcentral\.com\/chapters\/([0-9A-Z]{26})/.exec(prior.source?.url || '')?.[1];
+      if (weebId && uploads.has(weebId)) {
+        incoming.source = uploads.get(weebId);
+        totals[incoming.source.batch ? 'weebBatch' : 'weebSource']++;
+      } else if (dexBatch.has(version)) {
+        incoming.source = sourceDate(prior.added, prior.source.name, dexBatch.get(version));
+        prior.added = new Date(version.mtime).toISOString();
+        totals.mangaDexMoved++;
+      } else totals.missing++;
+      const next = { ...prior, ...publishedDates(prior, incoming, version.mtime) };
+      changed++; totals.changed++;
+      if (apply) await writeJsonAtomic(version.file, next);
+    }
+    if (changed) console.log(`[backfill] ${manga}: ${changed} of ${versions.length} chapter versions ${apply ? 'updated' : 'would change'}`);
+  }
+  console.log(JSON.stringify({ apply, ...totals }));
+  if (apply) console.log('Run a deep "Rescan" in Settings so the reader picks up the edited chapter.json files.');
+}
+
+main().catch(error => { console.error(error); process.exit(1); });