Try the capitalized title too, and reach Париж (V-668)

A ZIM title carries a leading capital and the utterance does not: /A/фотосинтез
is a 404 and /A/Фотосинтез is a 200. TitleCandidates tries the spoken form
first, so a title that begins lowercase on purpose keeps its chance.

That takes the measurement from four right to five, and the fifth is the one
that mattered. "столица Франции" returned "Список столиц Олимпийских игр"
and now returns Париж, through a title redirect the ZIM already held. The
2026-08-05 measurement named that case as the one no lexical signal could
reach. Retrieval by title reaches it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013ptwopxyo3Z2kwFckHkLvN

internal/kiwix/live_test.go

@@ -39,9 +39,13 @@ func TestLiveTopicBeatsTheSentence(t *testing.T) {
 		before := firstTitle(ctx, c, q, book)
 		topic := Topic(q)
 		after := ""
-		if page, err := c.Article(ctx, TitlePath(book, topic), 400); err == nil && page.Text != "" {
-			after = page.Title + " (by title)"
-		} else {
+		for _, cand := range TitleCandidates(topic) {
+			if page, err := c.Article(ctx, TitlePath(book, cand), 400); err == nil && page.Text != "" {
+				after = page.Title + " (by title)"
+				break
+			}
+		}
+		if after == "" {
 			after = firstTitle(ctx, c, topic, book)
 		}
 		cancel()

internal/kiwix/topic.go

@@ -61,6 +61,26 @@ func Topic(utterance string) string {
 	return ""
 }
 
+// TitleCandidates is the topic as it might be titled, best first.
+//
+// A ZIM title is capitalized and the utterance is not: measured on 2026-08-09,
+// `/A/фотосинтез` is a 404 and `/A/Фотосинтез` is a 200. The spoken form is
+// tried first anyway, because a title that begins lowercase on purpose
+// ("iPhone") would not survive capitalizing it. Both are one request each
+// against a server on the same box, and a miss is a 404 rather than a wrong
+// article.
+func TitleCandidates(topic string) []string {
+	if topic == "" {
+		return nil
+	}
+	r := []rune(topic)
+	up := unicode.ToUpper(r[0])
+	if up == r[0] {
+		return []string{topic}
+	}
+	return []string{topic, string(up) + string(r[1:])}
+}
+
 func isCopula(w string) bool {
 	switch w {
 	case "такое", "такой", "такая", "такие", "is", "are", "was", "were":

internal/kiwix/topic_test.go

@@ -49,3 +49,19 @@ func TestTitlePathEscapesAndUnderscores(t *testing.T) {
 		t.Errorf("TitlePath = %q, want %q", got, want)
 	}
 }
+
+// A ZIM title carries a leading capital and the utterance does not. The spoken
+// form is still tried first, so a title that begins lowercase on purpose keeps
+// its chance.
+func TestTitleCandidatesTryTheSpokenFormFirst(t *testing.T) {
+	got := TitleCandidates("фотосинтез")
+	if len(got) != 2 || got[0] != "фотосинтез" || got[1] != "Фотосинтез" {
+		t.Errorf("TitleCandidates = %q", got)
+	}
+	if got := TitleCandidates("TCP"); len(got) != 1 || got[0] != "TCP" {
+		t.Errorf("an already-capital topic was tried twice: %q", got)
+	}
+	if got := TitleCandidates(""); got != nil {
+		t.Errorf("TitleCandidates(\"\") = %q, want nil", got)
+	}
+}