2 files changed, 63 insertions, 0 deletions

diff --git a/internal/bible/booktable.go b/internal/bible/booktable.go
index eb3b4e4..007e75e 100644
--- a/internal/bible/booktable.go
+++ b/internal/bible/booktable.go
@@ -141,6 +141,38 @@ func (t *BookTable) ParseRef(dialect, input string) (string, bool) {
 	return "", false
 }
 
+// shortcut returns the dialect's primary abbreviation (the first form) for a
+// canonical book, or "" when the dialect has no entry for it.
+func (t *BookTable) shortcut(dialect, canonical string) string {
+	if forms := t.forms[dialect][canonical]; len(forms) > 0 {
+		return forms[0]
+	}
+	return ""
+}
+
+// FormatRef renders a canonical English reference ("John 20:1,11-18") in the
+// dialect's sigla: the dialect's book shortcut plus its number style -- English
+// "Jn 20:1,11-18" (colon chapter:verse, comma groups); Polish "J 20, 1. 11-18"
+// (comma chapter, verse; period groups). It is the inverse of ParseRef's
+// normalizeSigla. If canonicalRef can't be parsed or the book is not in the
+// dialect, it is returned unchanged (a safe, still-readable fallback).
+func (t *BookTable) FormatRef(dialect, canonicalRef string) string {
+	m := refRe.FindStringSubmatch(strings.TrimSpace(canonicalRef))
+	if m == nil {
+		return canonicalRef
+	}
+	canon, chap, verses := m[1], m[2], m[3]
+	abbrev := t.shortcut(dialect, canon)
+	if abbrev == "" {
+		return canonicalRef
+	}
+	if dialect == "pl" {
+		verses = strings.ReplaceAll(verses, ",", ". ") // disjoint groups
+		return abbrev + " " + chap + ", " + verses
+	}
+	return abbrev + " " + chap + ":" + verses
+}
+
 // normalizeSigla rewrites a dialect's verse-reference tail into the colon/comma
 // form bible.Lookup expects: "<chap>:<groups>", groups comma-separated, ranges
 // with "-". Polish uses a comma (with or without a space) as the chapter/verse
diff --git a/internal/bible/booktable_test.go b/internal/bible/booktable_test.go
index ededad3..2a57d80 100644
--- a/internal/bible/booktable_test.go
+++ b/internal/bible/booktable_test.go
@@ -64,6 +64,37 @@ func TestParseRefDialects(t *testing.T) {
 	}
 }
 
+func TestFormatRef(t *testing.T) {
+	tbl, _ := LoadBookTable(nil)
+	cases := []struct {
+		dialect, canonical, want string
+	}{
+		{"en", "John 20:1,11-18", "Jn 20:1,11-18"},
+		{"pl", "John 20:1,11-18", "J 20, 1. 11-18"},
+		{"en", "Matthew 13:18-23", "Matt 13:18-23"},
+		{"pl", "Matthew 13:18-23", "Mt 13, 18-23"},
+		{"en", "Luke 16:1-9", "Lk 16:1-9"},
+		// Round-trip: ParseRef then FormatRef in the same dialect is stable.
+	}
+	for _, c := range cases {
+		if got := tbl.FormatRef(c.dialect, c.canonical); got != c.want {
+			t.Errorf("FormatRef(%q,%q)=%q want %q", c.dialect, c.canonical, got, c.want)
+		}
+	}
+	// Unparseable / unknown book -> unchanged (safe fallback).
+	if got := tbl.FormatRef("en", "not a ref"); got != "not a ref" {
+		t.Errorf("unparseable ref should be unchanged, got %q", got)
+	}
+	// Round-trip through both dialects.
+	canon, ok := tbl.ParseRef("pl", "J 20, 1. 11-18")
+	if !ok || canon != "John 20:1,11-18" {
+		t.Fatalf("ParseRef round-trip canon=%q ok=%v", canon, ok)
+	}
+	if got := tbl.FormatRef("pl", canon); got != "J 20, 1. 11-18" {
+		t.Errorf("pl round-trip = %q", got)
+	}
+}
+
 func TestBookTableMergeAndMalformed(t *testing.T) {
 	// User adds an alias "Jhn" to English John; other books stay default.
 	user := []byte("[en]\nJohn = [\"Jn\", \"Jhn\", \"John\"]\n")