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mangaBookmark/docs/research/lightnovelworld-chapter-vs-series-slug.md
sulthan f1eb7d514c Record the lightnovelworld series-identity decision (#77) (#81)
Docs only. No code, no tests, nothing to run. Implementation is specified in #80.

Outcome of a grilling session on 2026-08-11 against #77, backed by live measurement of lightnovelworld over 2026-08-10/11.

## What changed

**`docs/adr/0008-series-identity-is-discovered-not-derived.md`** (new)

A Series identity is discovered from the Site's own links, never derived from an address.
On lightnovelworld the userscript reads the chapter page's `All Chapter` anchor instead of
building a `/novel/<slug>/` address by string manipulation. A Chapter Slug is not an
identity and is not stored. The backend's chapter scan drops its per-Series scoping and
runs against the body truncated before the visitor comment thread.

Evidence in the ADR: 3 of 41 sampled novels serve chapters under a slug that differs from
their series slug, divergence runs in both directions, one novel serves chapters under two
slugs, and neither slug is computable from the other. The pointer was checked on 8 chapter
pages and agreed every time. Three narrower selectors are recorded as rejected, each with
the measurement that killed it.

Three rejected options are recorded with reasons: correcting the stored address only, which
keeps an identity the Site does not guarantee; scoping the scan to a container, which the
probe refuted; and a SQL migration, which is impossible because the database holds no
source for the correct slug.

**`CONTEXT.md`**

- **Series** - identity is the canonical slug the Site publishes, never the title and never a Chapter Slug.
- **Chapter Slug** - new term. A slug a Site builds its chapter addresses from. Not an identity: one Series may have several, and none is computable from another.
- **Latest Chapter** - now the highest-numbered chapter, explicitly not a date and not the Site's own newest-chapter banner. Settles #79.

**`docs/research/lightnovelworld-chapter-vs-series-slug.md`** (new, committed with its corrections)

The 41-novel survey behind the ADR. Two claims are struck through and corrected in place,
with the date and sample size of the probe that refuted each: the `ul.clstyle` container it
named is the hidden, empty "Latest Reading" template rather than the chapter list, and its
caveat about the comment region understated the risk, because that region is writable by
any visitor while the scan takes an unbounded maximum into a Series row shared by every
Reader (ADR-0003).

## Review notes

Nothing here constrains code that exists today - the ADR describes work not yet written.
The part worth disagreeing with, if any of it is wrong, is the fail-closed rule: a missing
truncation marker means skip the Series and log, never scan the whole page.

Related: #77 (the defect), #80 (the spec), #79 (the numbering anomaly, closed by decision),
#71 (the same size cap seen from the cover side).

Reviewed-on: #81
Co-authored-by: Sulthan Zaki <sultankiki05@gmail.com>
Co-committed-by: Sulthan Zaki <sultankiki05@gmail.com>
2026-08-11 09:34:26 +07:00

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lightnovelworld.net — chapter slug vs. series slug

Research note for Gitea issue #77. All pages fetched live on 2026-08-11 with plain curl and a desktop UA. No Cloudflare challenge was encountered on any request — every fetch below returned real HTML on the first try, so the Playwright fallback was never needed.

Every claim carries the URL it came from. Nothing here is inferred from the existing code; where a claim is an interpretation rather than an observation it is marked [INFERENCE].


1. Summary answer table

Question Answer Evidence
Does the chapter slug equal the series slug? No, not reliably. 3 of 41 sampled novels diverge at their latest chapter (~7%); a 4th diverges historically. §4
Best chapter-page → series-URL pointer a[aria-label='All Chapter'] and the microdata breadcrumb a[itemprop=item] at position 2. Both carry the full absolute series URL. §3
Is JSON-LD BreadcrumbList usable? No. The Rank Math JSON-LD breadcrumb on a chapter page contains only Home and the chapter itself — the series is absent. §3.1
Is <link rel=canonical> usable? No. It points at the chapter page itself. §3.2
Are og: tags usable? No. og:url is the chapter page; no og: tag names the series. §3.3
Does the series page list chapters in the initial HTML? Yes — all of them. 1232 unique chapters (1…1232) present in one document. §5
Is there a paginated chapter endpoint? No. /novel/<slug>/chapters/ and /novel/<slug>/chapters/page-2 both 404. §5
Does the series page carry other novels' chapter anchors? No. Across 30 series pages, every -chapter-N/ URL belonged to the page's own novel. §6
Unscoped regex lightnovelworld\.net/[a-z0-9-]+-chapter-([0-9.]+)/ on a series page SAFE §6
Does /novel/<chapter-slug>/ 404? Yes, 404, no redirect. §7
Is there a chapter-slug → series-slug endpoint that avoids parsing a chapter page? No endpoint found. But /<chapter-slug>/ (no -chapter-N) 302s to chapter 1, which still requires parsing a chapter page. §7
Is there an "Alternative names" field explaining divergence? No such field exists on lightnovelworld series pages. §4.3

2. The two reference pages

URL Status
https://lightnovelworld.net/my-longevity-simulation-chapter-1/ 200, 0 redirects
https://lightnovelworld.net/novel/immortality-simulator/ 200, 0 redirects
https://lightnovelworld.net/novel/my-longevity-simulation/ 404, 0 redirects

Confirmed: chapter slug my-longevity-simulation, series slug immortality-simulator, and the naive /novel/<chapter-slug>/ construction is a hard 404.


3. Chapter page → series URL: every in-page pointer, in priority order

All snippets below are verbatim from https://lightnovelworld.net/my-longevity-simulation-chapter-1/.

Priority 1 — a[aria-label='All Chapter'] ✅ WORKS

Single occurrence in the document, inside the chapter navigation bar:

<div class="nvs nvsc"><a href='https://lightnovelworld.net/novel/immortality-simulator/' aria-label='All Chapter'><i class="fas fa-list-ul"></i> All Chapter</a></div>

Note the single quotes on both attributes — a regex written for href=" will miss it. This is the most narrowly-targeted pointer: exactly one element on the page has aria-label='All Chapter'.

Priority 2 — microdata BreadcrumbList / a[itemprop=item] ✅ WORKS

At line 363–379 of the served HTML. position 2 is the series:

<div itemscope="" itemtype="http://schema.org/BreadcrumbList">
	<span itemprop="itemListElement" itemscope="" itemtype="http://schema.org/ListItem">
		<a itemprop="item" href="https://lightnovelworld.net/"><span itemprop="name">Home</span></a>
		<meta itemprop="position" content="1">
	</span>
	›
	<span itemprop="itemListElement" itemscope="" itemtype="http://schema.org/ListItem">
		<a itemprop="item" href="https://lightnovelworld.net/novel/immortality-simulator/"><span itemprop="name">Immortality Simulator</span></a>
		<meta itemprop="position" content="2">
	</span>
	›
	<span itemprop="itemListElement" itemscope="" itemtype="http://schema.org/ListItem">
		<a itemprop="item" href="https://lightnovelworld.net/my-longevity-simulation-chapter-1/"><span itemprop="name">My Longevity Simulation Chapter 1</span></a>
		<meta itemprop="position" content="3">
	</span>
</div>

Bonus: <span itemprop="name">Immortality Simulator</span> gives the clean series title as well, which the userscript currently derives by stripping Chapter <n> off h1.entry-title.

Caveat: itemprop="item" is not unique to the breadcrumb — the site header nav also uses itemprop="url" on anchors, and unrelated itemprop="item" usage could appear. Scope any selector to the enclosing [itemtype="http://schema.org/BreadcrumbList"].

Priority 3 — corroborating /novel/ anchors ⚠️ AMBIGUOUS

The chapter page contains exactly 8 distinct /novel/… hrefs. Two are navigational (/novel/ index), one is the series, and five are a "recommended" strip of unrelated novels:

href="/novel/"
href="https://lightnovelworld.net/novel/"
href="https://lightnovelworld.net/novel/dreadful-radio-game/"
href="https://lightnovelworld.net/novel/evil-god-average/"
href="https://lightnovelworld.net/novel/immortality-simulator/"
href="https://lightnovelworld.net/novel/omniscient-first-persons-viewpoint/"
href="https://lightnovelworld.net/novel/reverend-insanity/"
href="https://lightnovelworld.net/novel/surviving-in-a-romance-fantasy-novel/"

So "grab the first /novel/<slug>/ link on a chapter page" is unsafe — the recommendation strip contaminates it. Use Priority 1 or 2.

❌ NOT usable — JSON-LD BreadcrumbList (§3.1)

There is exactly one application/ld+json block on the page (Rank Math SEO). Verbatim:

<script type="application/ld+json" class="rank-math-schema">{"@context":"https://schema.org","@graph":[{"@type":"BreadcrumbList","@id":"https://lightnovelworld.net/my-longevity-simulation-chapter-1/#breadcrumb","itemListElement":[{"@type":"ListItem","position":"1","item":{"@id":"https://lightnovelworld.net","name":"Home"}},{"@type":"ListItem","position":"2","item":{"@id":"https://lightnovelworld.net/my-longevity-simulation-chapter-1/","name":"My Longevity Simulation Chapter 1"}}]}]}</script>

Only two items — Home and the chapter. The series does not appear. The JSON-LD breadcrumb and the visible microdata breadcrumb disagree; the microdata one is the richer of the two. Do not use the JSON-LD.

<link rel="canonical" href="https://lightnovelworld.net/my-longevity-simulation-chapter-1/" />

Self-referential.

❌ NOT usable — og: meta tags (§3.3)

<meta property="og:type" content="article" />
<meta property="og:title" content="Read My Longevity Simulation Chapter 1 Online Free - LightNovelworld" />
<meta property="og:url" content="https://lightnovelworld.net/my-longevity-simulation-chapter-1/" />
<meta property="og:site_name" content="Light Novel World" />

og:url is the chapter. og:title carries the chapter-slug-derived title ("My Longevity Simulation"), not the series title ("Immortality Simulator") — so og tags actively reinforce the wrong name.

Also present — rel=next / rel=prev chapter navigation

<a aria-label="next" href="https://lightnovelworld.net/my-longevity-simulation-chapter-2/" rel="next">Next  <i class="fa fa-angle-right" aria-hidden="true"></i></a>

Chapter 1 has no rel=prev. Useful for walking chapters, useless for finding the series.


4. The reverse direction, and how common divergence is

4.1 Sample method

Two independent samples, deduplicated:

  • 14 novels taken from the latest-updates listing on https://lightnovelworld.net/ (distinct chapter slugs), each chapter page fetched and its aria-label='All Chapter' href read for the series slug.
  • 30 series URLs taken from https://lightnovelworld.net/novel/, each series page fetched and its chapter anchors' slug prefix extracted. Two of the 30 (/novel/feed/ and /novel/list-mode/) are not novels and are excluded, leaving 28.

One novel (investing-in-my-crippled-wife-every-return-makes-me-stronger) appears in both samples. Distinct novels sampled: 41.

4.2 Divergence results

Series slug (/novel/<…>/) Chapter slug (/<…>-chapter-N/) Result
immortality-simulator my-longevity-simulation DIVERGE
the-sword-illuminates-the-great-wilderness radiant-blade-of-the-wilderness DIVERGE
a-villains-will-to-survive the-villain-wants-to-live DIVERGE
all-jobs-and-classes-i-just-wanted-one-skill-not-them-all all-jobs-and-classes-i-just-wanted-one-skill-not (ch. 1–99) and all-jobs-and-classes-i-just-wanted-one-skill-not-them-all (ch. 100–423) SPLIT (latest matches)
86-eighty-six same match
a-dungeon-beneath-my-house-let-me-gain-800-exp same match
a-journey-of-black-and-red same match
a-knight-who-eternally-regresses same match
a-regressors-tale-of-cultivation same match
a-will-eternal same match
absolute-resonance same match
absolute-sword-sense same match
advent-of-the-three-calamities same match
after-changing-to-the-ruthless-way-the-brothers-cried-and-begged-for-forgiveness same match
against-the-gods same match
apocalypse-i-built-the-infinite-train same match
arcane-exfil same match
as-a-mafia-boss-i-refuse-to-be-an-extra same match
ascendance-of-a-bookworm same match
avatar-conquering-the-elements same match
battle-world-ascending-without-limits same match
became-the-patron-of-villains same match
ending-maker same match
got-dropped-into-a-ghost-story-still-gotta-work same match
greed-all-for-what same match
investing-in-my-crippled-wife-every-return-makes-me-stronger same match
lord-of-mysteries-2-circle-of-inevitability same match
lord-of-the-mysteries same match
my-vampire-system same match
cleaver-of-sin same match
greatest-legacy-of-the-magus-universe same match
magus-infinite same match
path-of-the-extra same match
regnum-aetern-dual-rebirth same match
shadow-slave same match
slime-evolution same match
sss-awakening-i-can-class-change-at-will same match
the-dao-of-reincarnation-ascending-through-a-hundred-lives same match
the-gamers-pov same match
the-insane-regressor-throne-of-pride same match
the-villains-pov same match

Counts (41 distinct novels):

  • 37 match (90.2%)
  • 3 diverge at the latest chapter (7.3%) — these are the ones that break the poller today
  • 1 splits mid-series but its newest chapters happen to match the series slug (2.4%)

[INFERENCE] The true site-wide divergence rate is probably in the same ballpark, but 41 novels out of a catalogue of thousands is a small sample and the listing page is alphabetically front-loaded. Treat ~7% as an order of magnitude, not a precise figure.

4.3 Is there a derivable rule? No.

The divergence is not directional, so you cannot compute one slug from the other:

  • immortality-simulator — the series carries the polished English title (<h1 class="entry-title" itemprop="name"> is absent from the chapter page's own naming; og:title says "My Longevity Simulation"), while the chapters carry the literal translation.
  • the-sword-illuminates-the-great-wilderness — the reverse: the series has the literal title (<h1 class="entry-title" itemprop="name">The Sword Illuminates the Great Wilderness</h1>, <title>Read The Sword Illuminates the Great Wilderness English Online Free - LightNovelworld</title>) while the chapters carry the polished one (radiant-blade-of-the-wilderness).
  • a-villains-will-to-survive — <h1 class="entry-title" itemprop="name">A Villain’s Will to Survive</h1>, chapters at the-villain-wants-to-live-chapter-N/.

[INFERENCE] The consistent explanation is that a novel is retitled after publication; WordPress updates the series post's slug but leaves the already-published chapter posts' slugs alone. The direction of the retitle varies per novel, which is why no rule exists. This is consistent with the split case in §4.4, but the site exposes no field that states it.

There is no "Alternative names" / "Associated names" field. Scanning https://lightnovelworld.net/novel/a-villains-will-to-survive/ and https://lightnovelworld.net/novel/immortality-simulator/ for such a label returns nothing; the series info panel exposes only Author, Released, Type, Status. (The only names? match in the document is the >Name*< label on the comment form.) So the old title is not recoverable from the series page — the mapping only exists in the chapter anchors themselves.

4.4 The split case — a slug can change mid-series

https://lightnovelworld.net/novel/all-jobs-and-classes-i-just-wanted-one-skill-not-them-all/ carries two chapter slugs in one page:

Chapter slug prefix Anchors Chapter range
all-jobs-and-classes-i-just-wanted-one-skill-not 100 1 – 99
all-jobs-and-classes-i-just-wanted-one-skill-not-them-all 325 100 – 423

Both resolve, and both point back at the same series:

200  https://lightnovelworld.net/all-jobs-and-classes-i-just-wanted-one-skill-not-chapter-1/
<a href='https://lightnovelworld.net/novel/all-jobs-and-classes-i-just-wanted-one-skill-not-them-all/' aria-label='All Chapter'>

200  https://lightnovelworld.net/all-jobs-and-classes-i-just-wanted-one-skill-not-them-all-chapter-404/
<a href='https://lightnovelworld.net/novel/all-jobs-and-classes-i-just-wanted-one-skill-not-them-all/' aria-label='All Chapter'>

Consequence: a single stored chapter slug is not a sufficient key even for one novel. A fix that captures "the chapter slug at bookmark time" and pins the poller regex to it would still miss chapters published under a later slug. This is the strongest argument for the unscoped regex over a stored-slug regex.


5. Series page → chapter list

From https://lightnovelworld.net/novel/immortality-simulator/ (200, 655 037 bytes):

  • 1234 anchors matching href="https://lightnovelworld.net/<slug>-chapter-<n>/".
  • 1232 unique chapter URLs, covering chapter numbers 1 through 1232 with no gaps.
  • The 2 extras are the First/Last shortcut widget, which duplicates two chapters:
<h2>Read Immortality Simulator</h2></div>
<div class="lastend">
  <div class="inepcx">
    <a href="https://lightnovelworld.net/my-longevity-simulation-chapter-1/">
      <span>First Chapter</span>
      <span class="epcur epcurfirst">Vol. 1 Ch. 1</span>
    </a>
  </div>
  <div class="inepcx">
    <a href="https://lightnovelworld.net/my-longevity-simulation-chapter-1232/">

The entire chapter list is in the initial HTML. No JS hydration, no pagination, no separate endpoint. Confirmed by probing the shapes the issue speculated about:

URL Status
https://lightnovelworld.net/novel/immortality-simulator/chapters/ 404
https://lightnovelworld.net/novel/immortality-simulator/chapters/page-2 404

The only page-numbers / pagination markup in the document belongs to class="wpdiscuz-comment-pagination" (the comment widget), not the chapter list.

This holds for large novels too: greed-all-for-what served 2666 chapter anchors and my-vampire-system 2547, all inline in one response.

All chapter hrefs are absolute (https://lightnovelworld.net/…). A grep for relative href="/<slug>-chapter-N/" on the series page returned 0 matches, so a pattern anchored on the literal host is safe.


6. Is the unscoped chapter regex SAFE on a series page?

Verdict: SAFE

Proposed pattern: lightnovelworld\.net/[a-z0-9-]+-chapter-([0-9.]+)/

Proof. For each of the 30 series pages fetched from https://lightnovelworld.net/novel/, every occurrence of <slug>-chapter-<n>/ anywhere in the document (href or not) was reduced to its slug prefix and deduplicated:

  • 27 of 28 real series pages had exactly 1 distinct chapter-slug prefix, equal to that novel's own chapter slug.
  • 1 page had 2 prefixes — all-jobs-and-classes-…, and §4.4 proves both belong to that same novel. Not foreign.
  • 0 pages carried any other novel's chapter URL.

The recommendation and sidebar widgets on a series page link to series URLs only, never chapter URLs. On https://lightnovelworld.net/novel/immortality-simulator/ the recommendation strip renders as:

<a href="https://lightnovelworld.net/novel/reverend-insanity/" itemprop="url" title="Reverend Insanity" class="tip" rel="292">

— /novel/<slug>/, which the pattern cannot match.

The one widget that would carry foreign chapter links, "Latest Reading", is an empty client-side template. Its container is display:none and its <ul> is empty in the served HTML; the row markup lives in an inert <span id="series-history-tpl" style='display:none'> with mustache placeholders and a href="#/{{number}}" — no real chapter URL:

<div class="bixbox bxcl" id="series-history" style="display:none;">
  <div class="releases"><h2>Latest Reading</h2></div>
  <div class="series-history-pool">
    <ul class="clstyle" id="series-history-ul"></ul>
  </div>
</div>
<span id="series-history-tpl" style='display:none'>
  <li data-id="{{id}}" data-num="{{chapter}}" data-vol="{{volume}}" data-title="{{title}}">
    <div class="chbox"><div class="eph-num">
      <a onclick="…return series_history.redirect({{id}});" href="#/{{number}}">

It is populated from the visitor's own local history, so a server-side fetch never sees content there — the poller is immune. A browser-rendered fetch with a fresh profile is likewise immune (no history to render).

Caveats to record with the verdict

  1. [INFERENCE] This is an empirical guarantee, not a structural one. Unlike the asura/novelfull cases where scoping to the slug makes foreign contamination impossible, here we only know that lightnovelworld's series template does not currently emit foreign chapter anchors. If the theme ever adds a "latest site updates" strip rendered server-side, the unscoped pattern breaks silently and in the worst direction (a foreign chapter number higher than the real one wins the maximum and the bookmark shows a phantom update).

    Correction, 2026-08-11. This caveat understated the risk. A series page server-renders a wpdiscuz comment thread below the chapter list, and comment bodies are HTML that can carry an <a href>. Verified on /novel/the-sword-illuminates-the-great-wilderness/: #wpdcom present, comment #wpd-comm-358_0 by "hasbi asy" rendered as <p>where's everyone</p> inside .wpd-comment-text, corroborated by that page's comment RSS feed; firstLoadWithAjax: 0 confirms the thread is in the initial HTML. The sampled pages carried 0 or 1 comments and no links, which is why §6 read clean. So the unscoped pattern does not merely depend on the theme staying unchanged — it reads a region any visitor can write to, and the scanner takes the maximum with no upper bound. The scan must stop before the comment thread.

  2. Consider scoping the match to the chapter-list container rather than the whole document, which would restore the structural guarantee at low cost. The list items sit under ul.clstyle (class="bixbox bxcl").

    Refuted, 2026-08-11, measured on 4 series pages (the-sword-illuminates-the-great-wilderness, all-jobs-…-them-all, a-will-eternal, immortality-simulator). The single ul.clstyle per page is the hidden, empty "Latest Reading" template (#series-history-ul, see §5), not the chapter list — scoping to it would match nothing. The real chapter list is a classless <ul> inside div.eplister.eplisterfull, in div.bixbox.bxcl.epcheck.

    The workable boundary is wpd-threads: it occurs exactly once per page, and on all 4 pages every chapter anchor precedes it and no chapter-shaped href follows it. wpdcom and wpdiscuz are unusable as markers — they occur 111 to 143 times per page, including in <head> roughly 15 KB before the chapter list, so cutting there would discard the list itself. id='comments' also occurs once but is single-quoted; the canonical id="comments" never appears.

  3. [0-9.]+ is fine: no decimal chapter numbers appeared anywhere in the sampled pages, but the existing strings.Trim(m[1], ".") guard already handles them.

  4. The current test fixture lnwSeriesFixture in backend/internal/latest/sites_test.go includes <a href="https://lightnovelworld.net/overgeared-chapter-9999/"> and asserts it is ignored. That anchor is not representative of a real series page — no sampled page contained a foreign chapter anchor. Relaxing the regex will make that assertion fail, and the correct response is to fix the fixture, not to keep the scoping.


7. Redirects and reverse-lookup endpoints

URL Status Redirects Final
https://lightnovelworld.net/novel/my-longevity-simulation/ 404 0 —
https://lightnovelworld.net/novel/radiant-blade-of-the-wilderness/ 404 0 —
https://lightnovelworld.net/immortality-simulator-chapter-1/ 404 0 —
https://lightnovelworld.net/my-longevity-simulation/ 200 1 https://lightnovelworld.net/my-longevity-simulation-chapter-1/

Two findings:

  1. /novel/<chapter-slug>/ genuinely 404s. Confirmed for both my-longevity-simulation and radiant-blade-of-the-wilderness. There is no alias, no 301, no fallback. Any stored series URL built by that construction is permanently dead.
  2. The chapter slug alone (no -chapter-N) 302s to chapter 1 of that novel. This is the closest thing to a reverse-lookup endpoint, but it lands on a chapter page, so recovering the series URL still requires parsing that page's aria-label='All Chapter' anchor or breadcrumb. No endpoint maps chapter slug → series slug directly.
  3. The inverse construction also fails: /<series-slug>-chapter-1/ 404s for a divergent novel, so you cannot probe your way from a series slug to a chapter slug either. The chapter slug must be read off the series page's anchors.

Also present but not a lookup path: the site is WordPress and exposes https://lightnovelworld.net/wp-json/wp/v2/posts/177695 (advertised via <link rel="alternate" title="JSON" type="application/json" …> on the chapter page). Whether the REST API exposes a chapter→series relation was not tested — out of scope for this note, and it would still require fetching the chapter page to learn the post ID.


8. Implications for issue #77

The issue text itself could not be read: gh is not installed in this environment, so issue://77 failed to resolve. The proposed regex quoted below is the one supplied in the task brief.

8.1 The bug

backend/internal/latest/sites.go:128-137 derives the chapter-anchor pattern from the series slug:

m := lnwSlugRe.FindStringSubmatch(u.Path)          // /novel/<series-slug>/
re = regexp.MustCompile(`lightnovelworld\.net/` + regexp.QuoteMeta(m[1]) + `-chapter-([0-9.]+)/`)

For immortality-simulator this compiles to a pattern matching …net/immortality-simulator-chapter-N/, which appears zero times on the series page — the anchors all say my-longevity-simulation. latestChapterFrom returns ok == false, indistinguishable from a Cloudflare challenge or a site redesign, and the bookmark silently stops tracking updates. Same for the-sword-illuminates-the-great-wilderness and a-villains-will-to-survive.

8.2 The proposed fix is sound

Dropping the scoping to lightnovelworld\.net/[a-z0-9-]+-chapter-([0-9.]+)/ is sound in shape and fixes all three currently-broken novels plus the split case in §4.4 — which no stored-slug approach can fix, since that novel legitimately has two chapter slugs. It must not be applied to the whole document, however: truncate the body at wpd-threads first, per the corrected caveat 2 in §6. The ul.clstyle suggestion originally recorded here is refuted.

Also worth removing: the overgeared-chapter-9999 line in lnwSeriesFixture and the "lightnovelworld takes the max and ignores another series" test case, which encode a contamination scenario that §6 shows does not occur on this site. Replacing them with a fixture that mirrors §4.4's two-slugs-one-novel reality would be a better regression test.

8.3 The userscript has the same bug, and it is worse

userscript/novel-bookmark.user.js builds the series URL by string-concatenating the chapter slug (lines 154 and 169):

seriesUrl: "https://lightnovelworld.net/novel/" + m[1] + "/",

For a divergent novel this writes a permanently-404 series URL into the database at bookmark time. Fixing only the backend regex leaves those rows broken, and fetchableSeriesURL will happily accept the dead URL because it only checks the hostname (sites.go:321-324).

The userscript should read the series URL off the page instead of constructing it. On a chapter page, prefer in this order (§3):

document.querySelector("a[aria-label='All Chapter']")?.href
  ?? document.querySelector("[itemtype$='BreadcrumbList'] a[itemprop=item][href*='/novel/']")?.href

The breadcrumb's <span itemprop="name"> also supplies the correct series title directly, replacing the current h1.entry-title + strip-Chapter <n> heuristic — which today yields "My Longevity Simulation" where the series is actually titled "Immortality Simulator".

A backfill for already-stored rows is likely needed: any lightnovelworld row whose series_url 404s can be repaired by fetching https://lightnovelworld.net/<series_id>-chapter-1/ (or /<series_id>/, which 302s there per §7) and reading its All Chapter anchor.

8.4 Note on series_id

Rows are keyed lightnovelworld:<series_id> where series_id is currently the chapter slug (from the userscript's m[1]). If the fix changes series_id to the real series slug, existing divergent bookmarks change key and need migrating. Whether that is worth it depends on whether series_id is used to rebuild URLs anywhere — sites.go uses the stored series_url, not series_id, for lightnovelworld, so storing the correct series_url may be sufficient without a re-key.


Reproduction

UA='Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0 Safari/537.36'

# §2 status codes
curl -sS -o /dev/null -w '%{http_code} %{url_effective}\n' -L -A "$UA" \
  https://lightnovelworld.net/my-longevity-simulation-chapter-1/ \
  https://lightnovelworld.net/novel/immortality-simulator/ \
  https://lightnovelworld.net/novel/my-longevity-simulation/

# §3 the two working pointers
curl -sS -A "$UA" https://lightnovelworld.net/my-longevity-simulation-chapter-1/ \
  | grep -E "aria-label='All Chapter'|itemprop=\"item\""

# §6 SAFE proof — distinct chapter-slug prefixes per series page (expect 1)
curl -sS -A "$UA" https://lightnovelworld.net/novel/immortality-simulator/ \
  | grep -oE '[a-z0-9-]+-chapter-[0-9.]+/' | sed -E 's/-chapter-[0-9.]+\///' | sort | uniq -c