backend/internal/latest/sites.go

@@ -1,6 +1,8 @@
 package latest
 
 import (
+	"encoding/json"
+	"html"
 	"net/url"
 	"regexp"
 	"strconv"
@@ -34,6 +36,18 @@ var demonicChapterRe = regexp.MustCompile(`chaptered\.php\?manga=\d+&(?:amp;)?ch
 // Only the id prefix is stable; the slug tail follows the title.
 var comixSlugRe = regexp.MustCompile(`/title/([^/?#]+)`)
 
+func comixSeriesID(seriesURL string) (string, bool) {
+	m := comixSlugRe.FindStringSubmatch(seriesURL)
+	if m == nil {
+		return "", false
+	}
+	id := m[1]
+	if i := strings.Index(id, "-"); i != -1 {
+		id = id[:i]
+	}
+	return id, true
+}
+
 // kaganeChapterRe matches the chapter numbers in a kagane API response. This
 // branch is fed by the browser fetcher, so the body is JSON rather than HTML —
 // there are no anchors to scan.
@@ -87,18 +101,14 @@ func latestChapterFrom(site, seriesURL, body string) (latestChapter, bool) {
 	case "demonic":
 		re = demonicChapterRe
 	case "comix":
-		m := comixSlugRe.FindStringSubmatch(seriesURL)
+		id, ok := comixSeriesID(seriesURL)
-		if m == nil {
+		if !ok {
 			return latestChapter{}, false
 		}
 		// comix ships an SPA: the served HTML carries a JSON state blob instead
 		// of chapter anchors, and latestChapterUrl is the only place the newest
 		// chapter appears. Scoping to this series' id prefix keeps a
 		// "recommended" strip's entries from winning the maximum.
-		id := m[1]
-		if i := strings.Index(id, "-"); i != -1 {
-			id = id[:i]
-		}
 		re = regexp.MustCompile(`"latestChapterUrl":"/title/` + regexp.QuoteMeta(id) + `-[^"]*-chapter-([0-9.]+)"`)
 	case "kagane":
 		re = kaganeChapterRe
@@ -146,3 +156,102 @@ func latestChapterFrom(site, seriesURL, body string) (latestChapter, bool) {
 	}
 	return best, found
 }
+
+var metaTagRe = regexp.MustCompile(`(?is)<meta\b[^>]*>`)
+var doubleQuotedMetaAttrRe = regexp.MustCompile(`(?is)([a-z][a-z0-9:_-]*)\s*=\s*"([^"]*)"`)
+var singleQuotedMetaAttrRe = regexp.MustCompile(`(?is)([a-z][a-z0-9:_-]*)\s*=\s*'([^']*)'`)
+
+// comix's server-rendered page embeds query data in this JSON script; parsing
+// the target detail entry avoids matching posters from recommended results.
+var comixInitialDataRe = regexp.MustCompile(`(?is)<script\b[^>]*\bid\s*=\s*["']initial-data["'][^>]*>(.*?)</script>`)
+
+// kagane's browser-fetched series response publishes cover image IDs under
+// series_covers. The API's canonical compressed image route is the only URL
+// form accepted by the store and browser fetcher; no rendition is guessed.
+func kaganeCoverURL(body string) string {
+	var response struct {
+		SeriesCovers []struct {
+			ImageID string `json:"image_id"`
+		} `json:"series_covers"`
+	}
+	if err := json.Unmarshal([]byte(body), &response); err != nil {
+		return ""
+	}
+	for _, cover := range response.SeriesCovers {
+		if kaganeImageIDRe.MatchString(cover.ImageID) {
+			return "https://kagane.to/api/v2/image/" + cover.ImageID + "/compressed"
+		}
+	}
+	return ""
+}
+
+func comixCoverURL(seriesURL, body string) string {
+	id, ok := comixSeriesID(seriesURL)
+	if !ok {
+		return ""
+	}
+	data := comixInitialDataRe.FindStringSubmatch(body)
+	if data == nil {
+		return ""
+	}
+	var state struct {
+		Queries map[string]json.RawMessage `json:"queries"`
+	}
+	if err := json.Unmarshal([]byte(data[1]), &state); err != nil {
+		return ""
+	}
+	raw := state.Queries[`["manga","detail","`+id+`"]`]
+	if len(raw) == 0 {
+		return ""
+	}
+	var detail struct {
+		Poster struct {
+			Medium string `json:"medium"`
+		} `json:"poster"`
+	}
+	if err := json.Unmarshal(raw, &detail); err != nil {
+		return ""
+	}
+	return publishedCoverURL(detail.Poster.Medium)
+}
+
+// coverFrom reports false for unknown sites, challenge bodies, and pages with
+// no usable cover. Metadata extraction keeps scanning after an empty match so
+// a later published cover is not hidden by an empty tag.
+func coverFrom(site, seriesURL, body string) (string, bool) {
+	var cover string
+	switch site {
+	case "asura", "demonic", "lightnovelworld":
+		cover = metaContent(body, "property", "og:image")
+	case "novelfull":
+		cover = metaContent(body, "name", "image")
+	case "comix":
+		cover = comixCoverURL(seriesURL, body)
+	case "kagane":
+		cover = kaganeCoverURL(body)
+	}
+	return cover, cover != ""
+}
+
+func metaContent(body, attrName, attrValue string) string {
+	for _, tag := range metaTagRe.FindAllString(body, -1) {
+		attrs := make(map[string]string)
+		for _, m := range doubleQuotedMetaAttrRe.FindAllStringSubmatch(tag, -1) {
+			attrs[strings.ToLower(m[1])] = m[2]
+		}
+		for _, m := range singleQuotedMetaAttrRe.FindAllStringSubmatch(tag, -1) {
+			attrs[strings.ToLower(m[1])] = m[2]
+		}
+		if strings.EqualFold(attrs[strings.ToLower(attrName)], attrValue) {
+			if cover := publishedCoverURL(attrs["content"]); cover != "" {
+				return cover
+			}
+		}
+	}
+	return ""
+}
+
+func publishedCoverURL(value string) string {
+	value = strings.TrimSpace(html.UnescapeString(value))
+	return strings.ReplaceAll(value, " ", "%20")
+}

backend/internal/latest/sites_test.go

@@ -79,6 +79,119 @@ const lnwSeriesFixture = `
 <a href="https://lightnovelworld.net/overgeared-chapter-9999/">Chapter 9999</a>
 `
 
+// Trimmed from https://asurascans.com/comics/chronicles-of-the-demon-faction-f886a8af
+// (redirected to ...-00dcbf97) on 2026-08-10.
+const asuraCoverFixture = `<meta property="og:image" content="https://cdn.asurascans.com/asura-images/covers/chronicles-of-the-demon-faction.d4dcb8.webp">`
+
+// Trimmed from https://demonicscans.org/manga/Catastrophic-Necromancer on 2026-08-10.
+// The source publishes the raw space in this URL.
+const demonicCoverFixture = `<meta property="og:image" content="https://readermc.org/images/thumbnails/Catastrophic Necromancer.webp">`
+
+// Trimmed from https://comix.to/title/n8we-dungeons-and-crayons on 2026-08-10.
+// The state includes a recommended poster before the target detail object and
+// nested IDs inside that object; no og:image is present.
+const comixCoverFixture = `<script type="application/json" id="initial-data">{"queries":{"[\"manga\",\"recommended\",\"n8we\",1]":{"poster":{"medium":"https://static.comix.to/recommended@280.jpg","large":"https://static.comix.to/recommended.jpg"}},"[\"manga\",\"detail\",\"n8we\"]":{"chapters":[{"hid":"nested"}],"poster":{"medium":"https://static.comix.to/039d/i/1/34/6a6742bf15736@280.jpg","large":"https://static.comix.to/039d/i/1/34/6a6742bf15736.jpg"}}}}</script>`
+
+// Trimmed from GET https://kagane.to/api/v2/series/019fe11a-8670-7cf3-8343-0b02057d3787 on 2026-08-10.
+const kaganeCoverFixture = `{"series_covers":[{"cover_id":"019fe11a-84d1-714b-9cf4-2827f277f3c0","language":"en","volume_number":"1","chapter_number":null,"note":null,"image_id":"019fe11a-84c3-7fc3-a84b-88787374b617"}]}`
+
+// Trimmed from https://novelfull.com/reverend-insanity.html on 2026-08-10.
+const novelfullCoverFixture = `<meta name="image" content="https://novelfull.com/uploads/webp/novel/reverend-insanity-82661d911a.webp">`
+
+// Trimmed from https://lightnovelworld.net/novel/a-will-eternal/ on 2026-08-10.
+const lnwCoverFixture = `<meta content='https://lightnovelworld.net/wp-content/uploads/2026/03/a-will-eternal-1.webp' property='og:image'>`
+
+func TestCoverFrom(t *testing.T) {
+	const comixURL = "https://comix.to/title/n8we-dungeons-and-crayons"
+	tests := []struct {
+		name      string
+		site      string
+		seriesURL string
+		body      string
+		wantOK    bool
+		wantCover string
+	}{
+		{
+			name: "asura uses published metadata URL",
+			site: "asura", body: asuraCoverFixture, wantOK: true,
+			wantCover: "https://cdn.asurascans.com/asura-images/covers/chronicles-of-the-demon-faction.d4dcb8.webp",
+		},
+		{
+			name: "demonic escapes raw spaces",
+			site: "demonic", body: demonicCoverFixture, wantOK: true,
+			wantCover: "https://readermc.org/images/thumbnails/Catastrophic%20Necromancer.webp",
+		},
+		{
+			name: "comix takes target medium poster",
+			site: "comix", seriesURL: comixURL, body: comixCoverFixture, wantOK: true,
+			wantCover: "https://static.comix.to/039d/i/1/34/6a6742bf15736@280.jpg",
+		},
+		{
+			name: "kagane reads API cover image ID",
+			site: "kagane", body: kaganeCoverFixture, wantOK: true,
+			wantCover: "https://kagane.to/api/v2/image/019fe11a-84c3-7fc3-a84b-88787374b617/compressed",
+		},
+		{
+			name: "novelfull reads image metadata",
+			site: "novelfull", body: novelfullCoverFixture, wantOK: true,
+			wantCover: "https://novelfull.com/uploads/webp/novel/reverend-insanity-82661d911a.webp",
+		},
+		{
+			name: "lightnovelworld reads og image",
+			site: "lightnovelworld", body: lnwCoverFixture, wantOK: true,
+			wantCover: "https://lightnovelworld.net/wp-content/uploads/2026/03/a-will-eternal-1.webp",
+		},
+		{
+			name:      "later metadata cover survives empty match",
+			site:      "asura",
+			body:      `<meta property="og:image" content="">` + asuraCoverFixture,
+			wantOK:    true,
+			wantCover: "https://cdn.asurascans.com/asura-images/covers/chronicles-of-the-demon-faction.d4dcb8.webp",
+		},
+		{
+			name: "page without cover is empty",
+			site: "asura", body: `<meta property="og:title" content="No Cover">`,
+		},
+		{
+			name: "unknown site is empty",
+			site: "unknown", body: asuraCoverFixture,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, ok := coverFrom(tt.site, tt.seriesURL, tt.body)
+			if ok != tt.wantOK {
+				t.Fatalf("ok = %v, want %v (got %q)", ok, tt.wantOK, got)
+			}
+			if got != tt.wantCover {
+				t.Errorf("cover = %q, want %q", got, tt.wantCover)
+			}
+		})
+	}
+}
+
+func TestCoverFromChallenge(t *testing.T) {
+	tests := []struct {
+		site      string
+		seriesURL string
+	}{
+		{"asura", "https://asurascans.com/comics/chronicles-of-the-demon-faction-f886a8af"},
+		{"demonic", "https://demonicscans.org/manga/Catastrophic-Necromancer"},
+		{"comix", "https://comix.to/title/n8we-dungeons-and-crayons"},
+		{"kagane", "https://kagane.to/series/019f84bc-9ba0-7ed9-86f5-8b905ec7c28b"},
+		{"novelfull", "https://novelfull.com/reverend-insanity.html"},
+		{"lightnovelworld", "https://lightnovelworld.net/novel/a-will-eternal/"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.site, func(t *testing.T) {
+			if got, ok := coverFrom(tt.site, tt.seriesURL, challengeFixture); ok || got != "" {
+				t.Fatalf("cover = %q, ok = %v, want empty", got, ok)
+			}
+		})
+	}
+}
+
 func TestLatestChapterFrom(t *testing.T) {
 	const asuraURL = "https://asurascans.com/comics/chronicles-of-the-demon-faction-f886a8af"
 	const demonicURL = "https://demonicscans.org/manga/Catastrophic-Necromancer"