Unify page routing and harden acquire wiring after review (#62)

backend/internal/latest/poller.go

@@ -116,16 +116,28 @@ func (p *Poller) storeCover(ctx context.Context, sr store.Series, sourceURL stri
 	}
 }
 
-// fetcherFor returns the fetcher a site needs, or nil when the site cannot be
-// fetched at all right now. kagane and novelfull both sit behind a Cloudflare
-// JavaScript challenge that no TLS fingerprint clears — kagane verified
-// 2026-08-03, novelfull verified 2026-08-05, both against the same Chrome_133
-// profile TLSFetcher uses — so they are browser-only or nothing.
-func (p *Poller) fetcherFor(site string) Fetcher {
-	if slices.Contains(browserBackedSites, site) {
-		return p.BrowserFetch
+// fetcherFor returns the fetcher a site's page needs, or nil when the site
+// cannot be fetched at all right now. kagane and novelfull pages sit behind a
+// Cloudflare JavaScript challenge that no TLS fingerprint clears (kagane
+// verified 2026-08-03, novelfull verified 2026-08-05, both against the same
+// Chrome_133 profile TLSFetcher uses), so both prefer the browser; novelfull
+// alone falls back to the plain-TLS fetcher when no browser is configured,
+// because its challenge is a live time-varying fact (AGENTS.md) and its cover
+// bytes never need the browser. kagane never falls back: a plain fetch of a
+// kagane page or cover would only ever retrieve a challenge page. One routing
+// rule for the poll and the acquirer, so the two cannot drift apart.
+func fetcherFor(site string, browser, tls Fetcher) Fetcher {
+	switch {
+	case site == "kagane":
+		return browser
+	case slices.Contains(browserBackedSites, site): // novelfull
+		if browser != nil {
+			return browser
+		}
+		return tls
+	default:
+		return tls
 	}
-	return p.Fetch
 }
 
 // Run polls until ctx is cancelled.
@@ -221,7 +233,7 @@ func (p *Poller) checkOne(ctx context.Context, sr store.Series) {
 		return
 	}
 
-	f := p.fetcherFor(sr.Site)
+	f := fetcherFor(sr.Site, p.BrowserFetch, p.Fetch)
 	if f == nil {
 		log.Printf("latest poll %q: no fetcher for site %q", sr.Key(), sr.Site)
 		return