Delete the kagane-specific cover path (#63)

The web proxy for kagane covers is dead: since #62 every Site's cover
bytes land in the content-addressed store at creation or on the poll,
and the one public route serves them all. Remove the second way to
reach a Cover:

- Bookmark.CoverURL() and the templates' use of it: templates render
  the wire value (.Cover) and nothing else.
- GET /img/kagane/{id}, web.CoverFetcher, coverIDRe: the route and its
  identifier validation are gone, and with them web/cover.go.
- store.KaganeImageID, GetKaganeCover, PutKaganeCover,
  kaganeCoverSourceURL: the proxy's persistence.
- Bookmark.CoverSource: dead once CoverURL is gone.

Acquisition keeps the browser where kagane genuinely needs it, but the
Site name leaves the routing: kaganeImageURLRe lives in browser.go with
the rest of the per-Site knowledge, browserCoverURL claims the URLs the
sidecar alone can fetch, and fetchCoverBytes routes by URL shape with
no Site argument. No plain-TLS fallback for a claimed URL — that would
only retrieve a challenge page.

Cover tests: kagane route tests removed, the general-route guarantees
they pinned kept and re-pinned — unstored and traversal-shaped
addresses serve nothing (TestPublicCoverRejectsUnknownAddress), non-image
content types are never echoed back (TestPublicCoverNeverEchoesNonImage
+ TestCoverStoreAcceptsAnySourceURL). Store content-addressing and
reopen-persistence tests rewritten against PutCover/GetCover.

No Site name remains in a cover code path outside the acquisition
module; go test ./... green.

backend/internal/latest/acquire.go

@@ -42,8 +42,8 @@ type Acquirer struct {
 	// Covers retrieves the cover bytes. Nil leaves the Cover blank and the
 	// chapter half working.
 	Covers CoverBytesFetcher
-	// BrowserCoverFetch retrieves kagane cover bytes through the browser
-	// sidecar. Nil leaves kagane Covers blank; nothing falls back to a plain
+	// BrowserCoverFetch retrieves browser-claimed cover bytes through the
+	// sidecar. Nil leaves those Covers blank; nothing falls back to a plain
 	// fetch, which would only ever retrieve a challenge page.
 	BrowserCoverFetch BrowserCoverFetcher
 	// Ctx cancels in-flight acquisitions at shutdown. A hook signature has
@@ -136,7 +136,7 @@ func (a *Acquirer) acquire(ctx context.Context, sr store.Series) {
 	if !ok {
 		return
 	}
-	bytes, contentType, err := fetchCoverBytes(ctx, sr.Site, cover, a.BrowserCoverFetch, a.Covers)
+	bytes, contentType, err := fetchCoverBytes(ctx, cover, a.BrowserCoverFetch, a.Covers)
 	if err != nil {
 		log.Printf("acquire %q: fetch cover %s: %v", sr.Key(), cover, err)
 		return

backend/internal/latest/acquire_test.go

@@ -312,8 +312,8 @@ func TestAcquireKaganeCoverThroughBrowser(t *testing.T) {
 	if got := covers.callCount(); got != 1 {
 		t.Fatalf("browser cover fetches = %d, want 1", got)
 	}
-	if got := covers.calls[0]; got != kaganeImageID {
-		t.Fatalf("browser cover fetched image id %q, want %q", got, kaganeImageID)
+	if got := covers.calls[0]; got != kaganeCoverSrc {
+		t.Fatalf("browser cover fetched URL %q, want %q", got, kaganeCoverSrc)
 	}
 	got := readBookmark(t, s, kaganeKey)
 	if want := testCoverBaseURL + "/covers/" + store.CoverAddress(kaganeCoverSrc); got.Cover != want {

backend/internal/latest/browser.go

@@ -24,12 +24,26 @@ const challengeTimeout = 45 * time.Second
 
 var kaganeSeriesRe = regexp.MustCompile(`^/series/([0-9a-f-]{36})/?$`)
 
-// kaganeImageIDRe pins the only path segment Image interpolates into an
-// outbound URL. The id arrives from a stored cover URL, which a client
-// supplied, so it is matched rather than trusted: a headless browser is a
-// strong SSRF primitive.
+// kaganeImageIDRe pins the only image id the kagane extractor accepts. It
+// arrives from the browser-fetched API body, so it is matched rather than
+// trusted.
 var kaganeImageIDRe = regexp.MustCompile(`^[0-9a-f-]{36}$`)
 
+// kaganeImageURLRe matches the only cover URL Image fetches: the canonical
+// compressed image route kagane's API publishes. It doubles as the byte-fetch
+// router's claim check (fetchCoverBytes) — an address of this shape answers a
+// plain fetch with a challenge, so the browser is the only route for it.
+var kaganeImageURLRe = regexp.MustCompile(`^https://kagane\.to/api/v2/image/([0-9a-f-]{36})/compressed$`)
+
+// browserCoverURL reports whether the browser sidecar is the only fetcher for
+// cover bytes at imageURL. kagane serves them behind the same challenge as its
+// pages, so a plain TLS fetch would only ever retrieve a challenge page and
+// must not be attempted (ADR-0007). Per-Site knowledge, kept in the browser
+// module with the rest of it.
+func browserCoverURL(imageURL string) bool {
+	return kaganeImageURLRe.MatchString(imageURL)
+}
+
 // BrowserFetcher retrieves pages through a remote headless Chrome over the
 // DevTools Protocol.
 //
@@ -134,12 +148,14 @@ func (f *BrowserFetcher) Get(ctx context.Context, seriesURL string) (string, int
 	return body, 200, nil
 }
 
-// Image retrieves one kagane cover as raw bytes and its content type.
+// Image retrieves one cover's bytes through the browser sidecar, and its
+// content type.
 //
 // It exists because kagane serves covers behind the same challenge as its
-// pages *and* with `cross-origin-resource-policy: same-origin`, so an <img> on
-// the web UI's origin cannot load one even from a browser that already holds
-// the clearance cookie (verified 2026-08-08). Proxying is the only route.
+// pages *and* with `cross-origin-resource-policy: same-origin`, so the bytes
+// are only reachable from inside a browser that already holds the clearance
+// cookie (verified 2026-08-08). Acquisition through the sidecar is the only
+// route.
 //
 // The image URL is navigated to rather than fetched from some other kagane
 // page: the challenge only runs on a top-level navigation, and once it clears
@@ -149,12 +165,14 @@ func (f *BrowserFetcher) Get(ctx context.Context, seriesURL string) (string, int
 // The challenge is not solved by the first read: WaitReady("body") is satisfied
 // by the interstitial too. run holds the tab open until the in-page fetch
 // succeeds, which is what gives the challenge script the seconds it needs.
-func (f *BrowserFetcher) Image(ctx context.Context, imageID string) ([]byte, string, error) {
-	if !kaganeImageIDRe.MatchString(imageID) {
-		return nil, "", fmt.Errorf("not a kagane image id: %q", imageID)
+func (f *BrowserFetcher) Image(ctx context.Context, imageURL string) ([]byte, string, error) {
+	m := kaganeImageURLRe.FindStringSubmatch(imageURL)
+	if m == nil {
+		return nil, "", fmt.Errorf("not a browser-fetchable cover url: %q", imageURL)
 	}
+	imageID := m[1]
 	var dataURL string
-	err := f.run(ctx, "https://kagane.to/api/v2/image/"+imageID+"/compressed",
+	err := f.run(ctx, imageURL,
 		chromedp.Evaluate(`fetch(location.href).then(r => r.ok
 			? r.blob().then(b => new Promise(res => {
 					const fr = new FileReader();

backend/internal/latest/cover.go

@@ -22,22 +22,19 @@ type CoverBytesFetcher interface {
 	Fetch(ctx context.Context, sourceURL string) (body []byte, contentType string, err error)
 }
 
-// fetchCoverBytes routes a cover's byte retrieval by Site: only kagane needs
-// the browser for image bytes — its covers answer a plain fetch with a
-// challenge and `cross-origin-resource-policy: same-origin` — while every
-// other Site's CDN answers plain TLS. Missing fetchers degrade to an error the
-// caller logs, never a fallback onto a path that cannot succeed. One routing
-// rule for the poll and the acquirer, so the two cannot drift apart.
-func fetchCoverBytes(ctx context.Context, site, cover string, browser BrowserCoverFetcher, tls CoverBytesFetcher) ([]byte, string, error) {
-	if site == "kagane" {
+// fetchCoverBytes routes a cover's byte retrieval by URL shape, not by Site
+// name: the browser fetcher's module claims the addresses only it can fetch
+// (kagane's image route answers a plain fetch with a challenge and
+// `cross-origin-resource-policy: same-origin`), and everything else goes over
+// plain TLS. Missing fetchers degrade to an error the caller logs, never a
+// fallback onto a path that cannot succeed. One routing rule for the poll and
+// the acquirer, so the two cannot drift apart.
+func fetchCoverBytes(ctx context.Context, cover string, browser BrowserCoverFetcher, tls CoverBytesFetcher) ([]byte, string, error) {
+	if browserCoverURL(cover) {
 		if browser == nil {
 			return nil, "", errors.New("no cover fetcher")
 		}
-		imageID, ok := store.KaganeImageID(cover)
-		if !ok {
-			return nil, "", errors.New("invalid kagane cover URL")
-		}
-		return browser.Image(ctx, imageID)
+		return browser.Image(ctx, cover)
 	}
 	if tls == nil {
 		return nil, "", errors.New("no cover fetcher")

backend/internal/latest/poller.go

@@ -16,9 +16,11 @@ type Fetcher interface {
 	Get(ctx context.Context, url string) (body string, status int, err error)
 }
 
-// BrowserCoverFetcher retrieves one kagane cover through the browser-backed path.
+// BrowserCoverFetcher retrieves one cover's bytes through the browser-backed
+// path — the only route that clears the challenge kagane's image URLs answer
+// a plain fetch with. Satisfied by BrowserFetcher.
 type BrowserCoverFetcher interface {
-	Image(ctx context.Context, imageID string) (body []byte, contentType string, err error)
+	Image(ctx context.Context, imageURL string) (body []byte, contentType string, err error)
 }
 
 // Poller re-checks each bookmarked series' newest published chapter on a
@@ -44,8 +46,8 @@ type Poller struct {
 	BrowserFetch Fetcher
 	// CoverFetch is optional; failures are logged and never affect the chapter poll.
 	CoverFetch BrowserCoverFetcher
-	// CoverBytesFetch is optional; it handles non-kagane sources through the same
-	// failure-isolated prefetch path.
+	// CoverBytesFetch is optional; it handles plain-TLS sources through the
+	// same failure-isolated prefetch path.
 	CoverBytesFetch CoverBytesFetcher
 	Now             func() time.Time // injected so tests can freeze it
 	Cooldown        time.Duration
@@ -81,9 +83,10 @@ func (p *Poller) fillBlankCover(ctx context.Context, sr store.Series, body strin
 
 // prefetchCover heals Series that already carry a third-party source URL but
 // no stored address — the state left by client-supplied covers before
-// acquisition moved server-side. Every Site takes the same path; only the
-// byte fetcher differs (kagane needs the browser). New blanks have no source
-// URL and go through fillBlankCover from the series page instead.
+// acquisition moved server-side. Every Site takes the same path; fetchCoverBytes
+// routes by URL shape, so browser-claimed URLs still need the sidecar. New
+// blanks have no source URL and go through fillBlankCover from the series page
+// instead.
 func (p *Poller) prefetchCover(ctx context.Context, sr store.Series) {
 	if sr.Cover == "" || sr.CoverAddress != "" {
 		return
@@ -106,7 +109,7 @@ func (p *Poller) prefetchCover(ctx context.Context, sr store.Series) {
 // failure is logged against the Series and swallowed so the chapter poll
 // cannot see it.
 func (p *Poller) storeCover(ctx context.Context, sr store.Series, sourceURL string) {
-	bytes, contentType, err := fetchCoverBytes(ctx, sr.Site, sourceURL, p.CoverFetch, p.CoverBytesFetch)
+	bytes, contentType, err := fetchCoverBytes(ctx, sourceURL, p.CoverFetch, p.CoverBytesFetch)
 	if err != nil {
 		log.Printf("latest poll %q: fetch cover %s: %v", sr.Key(), sourceURL, err)
 		return

backend/internal/latest/poller_test.go

@@ -116,9 +116,9 @@ type fakeCoverFetcher struct {
 	err         error
 }
 
-func (f *fakeCoverFetcher) Image(_ context.Context, imageID string) ([]byte, string, error) {
+func (f *fakeCoverFetcher) Image(_ context.Context, imageURL string) ([]byte, string, error) {
 	f.mu.Lock()
-	f.calls = append(f.calls, imageID)
+	f.calls = append(f.calls, imageURL)
 	f.mu.Unlock()
 	if f.err != nil {
 		return nil, "", f.err
@@ -778,9 +778,9 @@ func TestRunOncePrefetchesKaganeCover(t *testing.T) {
 	}
 	p.runOnce(context.Background())
 
-	body, contentType, ok, err := s.GetKaganeCover("019f84bc-9ba0-7ed9-86f5-8b905ec7c28b")
+	body, contentType, ok, err := s.CoverByAddress(store.CoverAddress(coverURL))
 	if err != nil || !ok {
-		t.Fatalf("GetKaganeCover: %v found=%v", err, ok)
+		t.Fatalf("CoverByAddress: %v found=%v", err, ok)
 	}
 	if string(body) != "cover-bytes" || contentType != "image/webp" {
 		t.Fatalf("stored cover = (%q, %q), want (cover-bytes, image/webp)", body, contentType)
@@ -877,7 +877,7 @@ func TestRunOnceRejectsInvalidKaganeCover(t *testing.T) {
 	}
 	p.runOnce(context.Background())
 
-	if _, _, found, err := s.GetKaganeCover("019f84bc-9ba0-7ed9-86f5-8b905ec7c28b"); err != nil || found {
+	if _, _, found, err := s.CoverByAddress(store.CoverAddress(coverURL)); err != nil || found {
 		t.Fatalf("invalid cover persisted = %v, err %v; want missing", found, err)
 	}
 }
@@ -902,7 +902,7 @@ func TestRunOnceWithoutCoverFetcherStillPollsKagane(t *testing.T) {
 	}
 	p.runOnce(context.Background())
 
-	if _, _, found, err := s.GetKaganeCover("019f84bc-9ba0-7ed9-86f5-8b905ec7c28b"); err != nil || found {
+	if _, _, found, err := s.CoverByAddress(store.CoverAddress(coverURL)); err != nil || found {
 		t.Fatalf("cover after nil CoverFetch = found %v, err %v; want missing", found, err)
 	}
 }

backend/internal/latest/smoke_image_test.go

@@ -10,9 +10,10 @@ import (
 	"bookmarkmanager/backend/internal/store"
 )
 
-// TestSmokeKaganeImage is the live proof that the cover proxy's fetch actually
-// clears Cloudflare and returns image bytes. It needs the real browser unit
-// with outbound network, so it runs only when SMOKE_BROWSER_WS_URL is set:
+// TestSmokeKaganeImage is the live proof that the acquisition path's browser
+// fetch actually clears Cloudflare and returns image bytes. It needs the real
+// browser unit with outbound network, so it runs only when SMOKE_BROWSER_WS_URL
+// is set:
 //
 //	cd chrome && BROWSER_BIND_ADDR=127.0.0.1 docker compose up -d --build
 //	SMOKE_BROWSER_WS_URL=ws://127.0.0.1:9222 go test -run TestSmokeKaganeImage ./internal/latest
@@ -24,12 +25,11 @@ func TestSmokeKaganeImage(t *testing.T) {
 	if ws == "" {
 		t.Skip("SMOKE_BROWSER_WS_URL unset")
 	}
-	const imageID = "019fe11a-84c3-7fc3-a84b-88787374b617" // SP Baby's cover
+	const imageURL = "https://kagane.to/api/v2/image/019fe11a-84c3-7fc3-a84b-88787374b617/compressed" // SP Baby's cover
 
-	// The same URL through a plain client is what the web UI's <img> gets.
+	// The same URL through a plain client is what any other fetcher would get.
 	// Asserting on it keeps the test honest about why the browser is needed.
-	req, err := http.NewRequest(http.MethodGet,
-		"https://kagane.to/api/v2/image/"+imageID+"/compressed", nil)
+	req, err := http.NewRequest(http.MethodGet, imageURL, nil)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -48,7 +48,7 @@ func TestSmokeKaganeImage(t *testing.T) {
 
 	ctx, cancel := context.WithTimeout(context.Background(), 90*time.Second)
 	defer cancel()
-	body, contentType, err := f.Image(ctx, imageID)
+	body, contentType, err := f.Image(ctx, imageURL)
 	if err != nil {
 		t.Fatalf("Image: %v", err)
 	}
@@ -64,8 +64,10 @@ func TestSmokeKaganeImage(t *testing.T) {
 	}
 	t.Logf("fetched %d bytes of %s", len(body), contentType)
 
-	if _, _, err := f.Image(ctx, "not-a-uuid"); err == nil {
-		t.Fatal("Image accepted a non-uuid id")
+	// The browser module claims only the cover URL shape it can clear a
+	// challenge for; anything else must be refused before any navigation.
+	if _, _, err := f.Image(ctx, "https://cdn.example/cover.jpg"); err == nil {
+		t.Fatal("Image accepted a cover URL the browser module does not claim")
 	}
 }
 

backend/internal/store/store.go

@@ -40,10 +40,6 @@ type Bookmark struct {
 	// address and never an address that 404s (ADR-0007). A client may still
 	// send this field and it is discarded on the way in; see Upsert.
 	Cover string `json:"cover"`
-	// CoverSource is the third-party address the bytes were fetched from. It
-	// stays off the wire: it is the acquisition path's dedupe key, and no
-	// client is ever asked to render one.
-	CoverSource      string   `json:"-"`
 	LastChapter      string   `json:"last_chapter"`
 	LastChapterNum   float64  `json:"last_chapter_num"`
 	LastChapterURL   string   `json:"last_chapter_url"`
@@ -155,20 +151,6 @@ func (b Bookmark) Initial() string {
 	return "?"
 }
 
-// kaganeCoverRe matches the cover URL kagane's og:image carries, which is what
-// the userscript stores for that site.
-var kaganeCoverRe = regexp.MustCompile(`^https://kagane\.to/api/v2/image/([0-9a-f-]{36})/compressed$`)
-
-// KaganeImageID extracts the validated image id from the cover URL recorded by
-// the userscript.
-func KaganeImageID(cover string) (string, bool) {
-	m := kaganeCoverRe.FindStringSubmatch(cover)
-	if m == nil {
-		return "", false
-	}
-	return m[1], true
-}
-
 // CoverContentType canonicalises a fetched response's media type and reports
 // whether the bytes are safe to store and serve. comix answers "image/jpg",
 // which no standard lists but browsers accept; it is stored as the real name
@@ -184,17 +166,6 @@ func CoverContentType(contentType string) (string, bool) {
 	}
 }
 
-// CoverURL is the src the web UI puts in an <img>. Cover already is an address
-// on this origin, so for every site but kagane it is used as-is. kagane's
-// bytes still arrive through the browser-backed proxy, which is keyed by image
-// id rather than by content address until #62 moves it onto the same path.
-func (b Bookmark) CoverURL() string {
-	if imageID, ok := KaganeImageID(b.CoverSource); ok {
-		return "/img/kagane/" + imageID
-	}
-	return b.Cover
-}
-
 // Library buckets. A bookmark is in exactly one. This cannot be derived from
 // Site: asurascans serves manga and novels from the same /comics/ path, so the
 // userscript that recorded the page is the only party that knows which.
@@ -217,7 +188,7 @@ var migrations embed.FS
 // compile-time constant; every request value is bound as a parameter. The
 // series-owned fields are joined in from the series table, in scanBookmark
 // order, so the flat Bookmark reads back whole despite the split (ADR-0004).
-const bookmarkColumns = `b.site, b.series_id, s.title, s.series_url, s.cover, s.cover_address,
+const bookmarkColumns = `b.site, b.series_id, s.title, s.series_url, s.cover_address,
 	b.last_chapter, b.last_chapter_num, b.last_chapter_url,
 	b.favorite, s.latest_chapter, s.latest_chapter_num, b.updated_at, b.status, s.kind`
 
@@ -562,7 +533,7 @@ func (s *Store) scanBookmark(scan func(...any) error) (Bookmark, error) {
 		latestChapterNum sql.NullFloat64
 	)
 	if err := scan(
-		&b.Site, &b.SeriesID, &b.Title, &b.SeriesURL, &b.CoverSource, &coverAddress,
+		&b.Site, &b.SeriesID, &b.Title, &b.SeriesURL, &coverAddress,
 		&b.LastChapter, &b.LastChapterNum, &b.LastChapterURL,
 		&b.Favorite, &b.LatestChapter, &latestChapterNum, &b.UpdatedAt, &b.Status, &b.Kind,
 	); err != nil {
@@ -617,10 +588,6 @@ func coverRelativePath(address string) string {
 	return address[:2] + "/" + address[2:4] + "/" + address
 }
 
-func kaganeCoverSourceURL(imageID string) string {
-	return "https://kagane.to/api/v2/image/" + imageID + "/compressed"
-}
-
 func (s *Store) getCover(sourceURL string) ([]byte, string, bool, error) {
 	return s.getCoverByAddress(coverSourceAddress(sourceURL))
 }
@@ -703,18 +670,6 @@ func (s *Store) PutCover(sourceURL string, body []byte, contentType string) erro
 	return s.putCover(sourceURL, body, contentType)
 }
 
-// GetKaganeCover returns one persisted cover. Missing covers are reported with
-// ok=false rather than as an error so the web handler can fetch them once.
-func (s *Store) GetKaganeCover(imageID string) ([]byte, string, bool, error) {
-	return s.getCover(kaganeCoverSourceURL(imageID))
-}
-
-// PutKaganeCover persists one fetched cover. The source URL's content address
-// makes each stored object immutable, so later writes for that URL are ignored.
-func (s *Store) PutKaganeCover(imageID string, body []byte, contentType string) error {
-	return s.putCover(kaganeCoverSourceURL(imageID), body, contentType)
-}
-
 // CoverAddress is the content address bytes fetched from sourceURL are stored
 // under. It is a pure function of the URL, so the acquisition path can name a
 // Cover before it has the bytes.

backend/internal/store/store_test.go

@@ -550,45 +550,6 @@ func TestDisplayChapter(t *testing.T) {
 	}
 }
 
-// CoverURL reads the source address for the kagane branch and the wire value
-// otherwise, so both are set the way scanBookmark sets them.
-func TestCoverURL(t *testing.T) {
-	cases := []struct {
-		name        string
-		coverSource string
-		cover       string
-		want        string
-	}{
-		{
-			"kagane routes through the proxy",
-			"https://kagane.to/api/v2/image/019fe11a-84c3-7fc3-a84b-88787374b617/compressed",
-			"https://bookmarks.test/covers/" + CoverAddress("kagane"),
-			"/img/kagane/019fe11a-84c3-7fc3-a84b-88787374b617",
-		},
-		{
-			"another site is served from our own origin",
-			"https://gg.asuracomic.net/storage/media/1/conversions/cover.webp",
-			"https://bookmarks.test/covers/" + CoverAddress("asura"),
-			"https://bookmarks.test/covers/" + CoverAddress("asura"),
-		},
-		{
-			"a lookalike host is not rewritten",
-			"https://evil.example/api/v2/image/019fe11a-84c3-7fc3-a84b-88787374b617/compressed",
-			"https://bookmarks.test/covers/" + CoverAddress("evil"),
-			"https://bookmarks.test/covers/" + CoverAddress("evil"),
-		},
-		{"no cover stays empty", "", "", ""},
-	}
-	for _, tc := range cases {
-		t.Run(tc.name, func(t *testing.T) {
-			b := Bookmark{CoverSource: tc.coverSource, Cover: tc.cover}
-			if got := b.CoverURL(); got != tc.want {
-				t.Errorf("CoverURL() = %q, want %q", got, tc.want)
-			}
-		})
-	}
-}
-
 func TestUpsertKindDefaultsToManga(t *testing.T) {
 	store := newTestStore(t)
 	got, err := store.Upsert(store.OwnerID(), Bookmark{
@@ -1397,7 +1358,7 @@ func TestTwoReadersShareOneSeriesWithIndependentProgress(t *testing.T) {
 		t.Fatalf("due after one Reader left = %+v, want the series still polled", due)
 	}
 }
-func TestKaganeCoverPersistsAcrossReopen(t *testing.T) {
+func TestCoverPersistsAcrossReopen(t *testing.T) {
 	url := pgtest.URL(t)
 	coverDir := t.TempDir()
 	first, err := Open(url, testOwner, coverDir, testCoverBaseURL)
@@ -1405,8 +1366,9 @@ func TestKaganeCoverPersistsAcrossReopen(t *testing.T) {
 		t.Fatalf("Open: %v", err)
 	}
 	body := []byte("stored-cover")
-	if err := first.PutKaganeCover("019fe11a-84c3-7fc3-a84b-88787374b617", body, "image/webp"); err != nil {
-		t.Fatalf("PutKaganeCover: %v", err)
+	const sourceURL = "https://cdn.example/covers/series.jpg"
+	if err := first.PutCover(sourceURL, body, "image/webp"); err != nil {
+		t.Fatalf("PutCover: %v", err)
 	}
 	if err := first.Close(); err != nil {
 		t.Fatalf("close first store: %v", err)
@@ -1417,9 +1379,9 @@ func TestKaganeCoverPersistsAcrossReopen(t *testing.T) {
 		t.Fatalf("reopen: %v", err)
 	}
 	defer second.Close()
-	got, contentType, ok, err := second.GetKaganeCover("019fe11a-84c3-7fc3-a84b-88787374b617")
+	got, contentType, ok, err := second.GetCover(sourceURL)
 	if err != nil {
-		t.Fatalf("GetKaganeCover: %v", err)
+		t.Fatalf("GetCover: %v", err)
 	}
 	if !ok || !bytes.Equal(got, body) || contentType != "image/webp" {
 		t.Fatalf("stored cover = (%q, %q, %v), want (%q, image/webp, true)", got, contentType, ok, body)
@@ -1443,7 +1405,7 @@ func TestOpenRequiresAbsoluteCoverBaseURL(t *testing.T) {
 	}
 }
 
-func TestKaganeCoverIsContentAddressedOnFilesystem(t *testing.T) {
+func TestCoverIsContentAddressedOnFilesystem(t *testing.T) {
 	url := pgtest.URL(t)
 	coverDir := t.TempDir()
 	first, err := Open(url, testOwner, coverDir, testCoverBaseURL)
@@ -1451,14 +1413,13 @@ func TestKaganeCoverIsContentAddressedOnFilesystem(t *testing.T) {
 		t.Fatalf("Open: %v", err)
 	}
 	body := []byte("stored-cover")
-	const imageID = "019fe11a-84c3-7fc3-a84b-88787374b617"
-	if err := first.PutKaganeCover(imageID, body, "image/webp"); err != nil {
+	const sourceURL = "https://cdn.example/covers/series.jpg"
+	if err := first.PutCover(sourceURL, body, "image/webp"); err != nil {
 		first.Close()
-		t.Fatalf("PutKaganeCover: %v", err)
+		t.Fatalf("PutCover: %v", err)
 	}
 	defer first.Close()
 
-	sourceURL := "https://kagane.to/api/v2/image/" + imageID + "/compressed"
 	addressBytes := sha256.Sum256([]byte(sourceURL))
 	address := hex.EncodeToString(addressBytes[:])
 	wantPath := filepath.Join(address[:2], address[2:4], address)

backend/internal/web/cover.go

@@ -1,89 +0,0 @@
-package web
-
-import (
-	"bookmarkmanager/backend/internal/store"
-	"context"
-	"log"
-	"net/http"
-	"regexp"
-	"time"
-)
-
-// CoverFetcher retrieves one kagane cover by image id. Satisfied by
-// latest.BrowserFetcher. It is nil when BROWSER_WS_URL is unset; uncached
-// covers are then unavailable, while covers already stored by the backend
-// remain available without a browser.
-type CoverFetcher interface {
-	Image(ctx context.Context, imageID string) (body []byte, contentType string, err error)
-}
-
-// coverIDRe matches the request path segment that becomes part of an outbound
-// URL. The proxy is session-gated, but the id still reaches a headless browser,
-// so it is validated at the boundary rather than passed through.
-var coverIDRe = regexp.MustCompile(`^[0-9a-f-]{36}$`)
-
-// coverTimeout bounds one proxied cover. Shorter than the fetcher's own
-// challenge budget on purpose: a browser page is waiting on this, and a cover
-// that has not arrived by now is better left as a broken slot than as a request
-// holding a connection open.
-const coverTimeout = 20 * time.Second
-
-// kaganeCover serves a kagane cover from the backend's own origin.
-//
-// kagane answers image requests with a Cloudflare challenge and
-// `cross-origin-resource-policy: same-origin`, so the web UI cannot render one
-// directly under any combination of referrer policy or crossorigin attribute
-// (verified 2026-08-08). Fetching it through the headless browser that already
-// clears the challenge, and re-serving it here, is what puts the bytes on an
-// origin the page may load from.
-func (h *Handler) kaganeCover(w http.ResponseWriter, r *http.Request) {
-	id := r.PathValue("id")
-	if !coverIDRe.MatchString(id) {
-		http.NotFound(w, r)
-		return
-	}
-	body, contentType, ok, err := h.store.GetKaganeCover(id)
-	if err != nil {
-		log.Printf("read kagane cover %s: %v", id, err)
-		http.Error(w, "internal error", http.StatusInternalServerError)
-		return
-	}
-	if ok {
-		writeCover(w, body, contentType)
-		return
-	}
-	if h.covers == nil {
-		http.NotFound(w, r)
-		return
-	}
-
-	ctx, cancel := context.WithTimeout(r.Context(), coverTimeout)
-	defer cancel()
-	body, contentType, err = h.covers.Image(ctx, id)
-	if err != nil {
-		log.Printf("kagane cover %s: %v", id, err)
-		http.NotFound(w, r)
-		return
-	}
-	canonical, ok := store.CoverContentType(contentType)
-	if !ok {
-		log.Printf("kagane cover %s: unexpected content type %q", id, contentType)
-		http.NotFound(w, r)
-		return
-	}
-	contentType = canonical
-	if err := h.store.PutKaganeCover(id, body, contentType); err != nil {
-		log.Printf("persist kagane cover %s: %v", id, err)
-		http.Error(w, "internal error", http.StatusInternalServerError)
-		return
-	}
-	writeCover(w, body, contentType)
-}
-
-// writeCover sends the bytes with a long cache life: an image id names one
-// immutable rendering, so a client that has it never needs to ask again.
-func writeCover(w http.ResponseWriter, body []byte, contentType string) {
-	w.Header().Set("Content-Type", contentType)
-	w.Header().Set("Cache-Control", "private, max-age=604800, immutable")
-	w.Write(body)
-}

backend/internal/web/templates/card.html

@@ -6,7 +6,7 @@
   <div class="row">
     <a class="cover" href="{{.ContinueURL}}" target="_blank" rel="noopener noreferrer"
        tabindex="-1" aria-hidden="true">
-      {{if .CoverURL}}<img src="{{.CoverURL}}" alt="" loading="lazy">
+      {{if .Cover}}<img src="{{.Cover}}" alt="" loading="lazy">
       {{/* aria-hidden on the cover link is not enough — Chromium still exposes
            the letter because the link is programmatically focusable — so the
            monogram carries its own, same as the recent strip's. */}}

backend/internal/web/templates/chrome.html

@@ -14,7 +14,7 @@
     <a class="recent-card {{if .HasNewChapter}}is-new{{end}}" href="{{.ContinueURL}}"
        target="_blank" rel="noopener noreferrer">
       <span class="recent-cover">
-        {{if .CoverURL}}<img src="{{.CoverURL}}" alt="" loading="lazy">
+        {{if .Cover}}<img src="{{.Cover}}" alt="" loading="lazy">
         {{else}}<span class="monogram" aria-hidden="true">{{.Initial}}</span>{{end}}
         {{if .HasNewChapter}}<span class="foot-rule"></span>
         {{else if .Favorite}}<span class="foot-rule brass"></span>{{end}}

backend/internal/web/web.go

@@ -50,9 +50,6 @@ type Handler struct {
 	// httpClient is the plain stdlib client that talks to Discord. It is not
 	// an injected interface: tests point APIBase at a stub server instead.
 	httpClient *http.Client
-	// covers proxies kagane cover images, which no browser can load directly.
-	// Nil disables the endpoint — see CoverFetcher.
-	covers CoverFetcher
 }
 
 // listView is what every list-rendering template receives.
@@ -114,7 +111,7 @@ type loginView struct {
 
 // New parses every template up front so a broken one kills the process at
 // startup rather than the first request that touches it.
-func New(s *store.Store, discord DiscordConfig, tokenKey []byte, mangaPath, novelPath string, covers CoverFetcher) (*Handler, error) {
+func New(s *store.Store, discord DiscordConfig, tokenKey []byte, mangaPath, novelPath string) (*Handler, error) {
 	tmpl, err := template.ParseFS(templateFS, "templates/*.html")
 	if err != nil {
 		return nil, err
@@ -129,7 +126,6 @@ func New(s *store.Store, discord DiscordConfig, tokenKey []byte, mangaPath, nove
 		states:              newOAuthStates(),
 		limiter:             session.NewLoginLimiter(),
 		httpClient:          &http.Client{Timeout: discordTimeout},
-		covers:              covers,
 	}, nil
 }
 
@@ -146,10 +142,6 @@ func (h *Handler) Register(mux *http.ServeMux) {
 	mux.HandleFunc("POST /ui/bookmarks/{key}/chapter", h.requireSession(h.uiChapter))
 	mux.HandleFunc("DELETE /ui/bookmarks/{key}", h.requireSession(h.uiDelete))
 
-	// Session-gated like every other UI route: the deployment proxies kagane's
-	// images for its own Readers, not for the internet.
-	mux.HandleFunc("GET /img/kagane/{id}", h.requireSession(h.kaganeCover))
-
 	// Install endpoints render the script directly under the session: the
 	// credential travels inside the served bytes, never in the address bar or
 	// the page markup. Updates after install use the credential-bearing /u/