#88: review — drop dead anchor branch, single marker scan in canary helper

backend/internal/latest/smoke_lnw_test.go

@@ -63,10 +63,11 @@ func TestSmokeLnwCommentBoundary(t *testing.T) {
 	if !lnwChapterRe.MatchString(body) {
 		t.Fatalf("no chapter anchor in %d bytes — not a lightnovelworld Series page; not a marker failure, likely a Cloudflare challenge or a non-Series response", len(body))
 	}
+	markerIdx := strings.Index(body, lnwCommentMarker)
 	if failures := checkLnwCommentBoundary(body); len(failures) > 0 {
 		t.Fatalf("%s (body %d bytes)", strings.Join(failures, "; "), len(body))
 	}
-	t.Logf("ok: %q once at byte %d, body %d bytes", lnwCommentMarker, strings.Index(body, lnwCommentMarker), len(body))
+	t.Logf("ok: %q once at byte %d, body %d bytes", lnwCommentMarker, markerIdx, len(body))
 }
 
 // checkLnwCommentBoundary verifies the three marker assertions against a
@@ -75,29 +76,25 @@ func TestSmokeLnwCommentBoundary(t *testing.T) {
 // human-readable failure per broken assertion — with observed offsets and body
 // length — and empty when the page is healthy.
 func checkLnwCommentBoundary(body string) []string {
-	n := strings.Count(body, lnwCommentMarker)
-	if n == 0 {
-		return []string{fmt.Sprintf("%q occurs 0 times in %d bytes, want exactly 1", lnwCommentMarker, len(body))}
-	}
-	if n != 1 {
-		return []string{fmt.Sprintf("%q occurs %d times in %d bytes (first at byte %d), want exactly 1", lnwCommentMarker, n, len(body), strings.Index(body, lnwCommentMarker))}
-	}
 	markerIdx := strings.Index(body, lnwCommentMarker)
-	lastAnchor, before := -1, 0
+	switch n := strings.Count(body, lnwCommentMarker); {
+	case n == 0:
+		return []string{fmt.Sprintf("%q occurs 0 times in %d bytes, want exactly 1", lnwCommentMarker, len(body))}
+	case n != 1:
+		return []string{fmt.Sprintf("%q occurs %d times in %d bytes (first at byte %d), want exactly 1", lnwCommentMarker, n, len(body), markerIdx)}
+	}
+	lastAnchor, anchorsBefore := -1, 0
 	for _, m := range lnwChapterRe.FindAllStringIndex(body, -1) {
 		if m[0] < markerIdx {
-			before++
+			anchorsBefore++
 		}
 		lastAnchor = m[0]
 	}
-	if lastAnchor == -1 {
-		return []string{fmt.Sprintf("no chapter anchor in the %d-byte body", len(body))}
-	}
 	var failures []string
 	if lastAnchor >= markerIdx {
 		failures = append(failures, fmt.Sprintf("last chapter anchor at byte %d does not precede the marker at byte %d", lastAnchor, markerIdx))
 	}
-	if before == 0 {
+	if anchorsBefore == 0 {
 		failures = append(failures, fmt.Sprintf("no chapter anchor before the marker at byte %d — the truncated prefix the scan sees yields nothing", markerIdx))
 	}
 	return failures