2 files changed, 24 insertions, 0 deletions
diff --git a/lib/citation/book.ml b/lib/citation/book.ml
index 545e324..2a2b9c0 100644
--- a/lib/citation/book.ml
+++ b/lib/citation/book.ml
@@ -78,6 +78,11 @@ let all = List.map fst table @ tradition_targets
 let tokens =
   List.concat_map (fun (id, sp) -> List.map (fun s -> (s, id)) sp) table
 
+let default_spelling id =
+  match List.assoc_opt id table with
+  | Some (first :: _) -> first
+  | Some [] | None -> id
+
 let of_token s =
   let s = String.trim s in
   List.assoc_opt s tokens
diff --git a/lib/citation/book.mli b/lib/citation/book.mli
index 8918bc3..0ca229c 100644
--- a/lib/citation/book.mli
+++ b/lib/citation/book.mli
@@ -36,6 +36,25 @@ val all : id list
 (** Every accepted spelling paired with its id. *)
 val tokens : (string * id) list
 
+(** The first spelling registered for an id -- the form the shipped data
+    itself uses ([luke] -> ["Luke"], [kings_3] -> ["3 Kings"]).
+
+    This is the FALLBACK display name, and it exists because the obvious
+    alternative is actively worse. A language file's [\[bible\]] lookup is
+    total and returns THE KEY on a miss, so a book with no entry would
+    otherwise render as ["luke.abbr 5:12-14"]. Falling back here instead makes
+    an unnamed book render as ["Luke 5:12-14"] -- exactly what colitur printed
+    before this feature existed. The degraded case is the OLD behaviour, not a
+    broken page, the same principle {!Colitur_naming.Lang} states for its own
+    key-returning misses.
+
+    An id with no registered spelling -- only a {!tradition} target such as
+    [kings_1] or [sirach], which the Vulgate data never cites -- returns the id
+    itself. Reachable only from a user language file that selects a tradition
+    without naming its target books; every SHIPPED language file is asserted
+    complete over {!all}. *)
+val default_spelling : id -> string
+
 (** A numbering tradition: which book an id denotes. Separate from NAMING
     (what a book is called), which lives in a language file's [\[bible\]]
     section, because naming varies by language and this does not -- "modern