Label chapter chips by kind, not raw number

Beats, tags, locations, open questions, and character/arc-stage
responses that reference a chapter now carry a ChapterLabel/DisplayNumber
alongside the raw Number, computed via the new
ChapterDisplayNumberLookup. Front/back matter chips show their title;
body chapters show "Chapter N: Title".

src/Novelly.Api/Chapters/ChapterDisplayNumberLookup.cs

@@ -0,0 +1,38 @@
+using Microsoft.EntityFrameworkCore;
+using Novelly.Api.Data;
+
+namespace Novelly.Api.Chapters;
+
+public class ChapterDisplayNumberLookup(INovelDbContext db)
+{
+    public async Task<IReadOnlyDictionary<Guid, int>> ForNovelAsync(Guid novelId, CancellationToken ct = default)
+    {
+        var chapters = await db.Chapters.AsNoTracking().Where(c => c.NovelId == novelId).ToListAsync(ct);
+        return ChapterNumbering.DisplayNumbers(chapters);
+    }
+
+    public async Task<int?> ForChapterAsync(Chapter chapter, CancellationToken ct = default)
+    {
+        if (chapter.Kind != ChapterKind.Body)
+            return null;
+
+        return await db.Chapters.CountAsync(
+            c => c.NovelId == chapter.NovelId && c.Kind == ChapterKind.Body && c.Number <= chapter.Number, ct);
+    }
+
+    public async Task<IReadOnlyDictionary<Guid, int>> ForChaptersAsync(IEnumerable<Chapter> chapters, CancellationToken ct = default)
+    {
+        var displayNumbers = new Dictionary<Guid, int>();
+
+        foreach (var chapter in chapters.DistinctBy(c => c.Id))
+        {
+            if (await ForChapterAsync(chapter, ct) is { } number)
+                displayNumbers[chapter.Id] = number;
+        }
+
+        return displayNumbers;
+    }
+
+    public string LabelFor(Chapter chapter, IReadOnlyDictionary<Guid, int> displayNumbers) =>
+        ChapterNumbering.Label(chapter.Kind, displayNumbers.TryGetValue(chapter.Id, out var n) ? n : null, chapter.Title);
+}

src/Novelly.Api/Chapters/ChapterService.cs

@@ -14,6 +14,7 @@ public class ChapterService(
     NovelAccessService access,
     TagService tags,
     LocationService locations,
+    ChapterDisplayNumberLookup displayNumbers,
     ActivityLog activity,
     ILogger<ChapterService> logger,
     IModelValidator<CreateChapterRequest> createValidator,
@@ -168,14 +169,8 @@ public class ChapterService(
         return true;
     }
 
-    public async Task<int?> DisplayNumberAsync(Chapter chapter, CancellationToken ct = default)
-    {
-        if (chapter.Kind != ChapterKind.Body)
-            return null;
-
-        return await db.Chapters.CountAsync(
-            c => c.NovelId == chapter.NovelId && c.Kind == ChapterKind.Body && c.Number <= chapter.Number, ct);
-    }
+    public Task<int?> DisplayNumberAsync(Chapter chapter, CancellationToken ct = default) =>
+        displayNumbers.ForChapterAsync(chapter, ct);
 
     private async Task<int> NextChapterNumberAsync(Guid novelId, CancellationToken ct)
     {