update detail.

API/ROLAC.API/Services/DisbursementService.cs

@@ -40,6 +40,19 @@ public class DisbursementService : IDisbursementService
         var memberIds = rows.Where(r => r.MemberId != null).Select(r => r.MemberId!.Value).ToHashSet();
         var members = await _db.Members.AsNoTracking().Where(m => memberIds.Contains(m.Id)).ToDictionaryAsync(m => m.Id);
 
+        // Category label per expense: the single line's category, or "Multiple" when it spans several.
+        var expenseIds = rows.Select(r => r.Id).ToList();
+        var lineGroups = await _db.ExpenseLines.AsNoTracking()
+            .Where(l => expenseIds.Contains(l.ExpenseId))
+            .OrderBy(l => l.Id)
+            .Select(l => new { l.ExpenseId, l.CategoryGroupId })
+            .ToListAsync();
+        var categoryByExpense = lineGroups.GroupBy(l => l.ExpenseId).ToDictionary(
+            g => g.Key,
+            g => g.Select(l => l.CategoryGroupId).Distinct().Count() > 1
+                ? "Multiple / 多類別"
+                : grpNames.GetValueOrDefault(g.First().CategoryGroupId, ""));
+
         var groups = new Dictionary<string, PayeeGroupDto>();
         foreach (var e in rows)
         {
@@ -77,7 +90,7 @@ public class DisbursementService : IDisbursementService
                 ExpenseId = e.Id, ExpenseDate = e.ExpenseDate.ToString("yyyy-MM-dd"),
                 Description = e.Description, Amount = e.Amount,
                 MinistryName = minNames.GetValueOrDefault(e.MinistryId, ""),
-                CategoryName = grpNames.GetValueOrDefault(e.CategoryGroupId, ""),
+                CategoryName = categoryByExpense.GetValueOrDefault(e.Id, ""),
             });
             g.TotalAmount += e.Amount;
         }

API/ROLAC.API/Services/ExpenseService.cs

@@ -35,8 +35,9 @@ public class ExpenseService : IExpenseService
     {
         var query = _db.Expenses.AsNoTracking().AsQueryable();
         if (ministryId.HasValue)      query = query.Where(e => e.MinistryId == ministryId.Value);
-        if (categoryGroupId.HasValue) query = query.Where(e => e.CategoryGroupId == categoryGroupId.Value);
-        if (subCategoryId.HasValue)   query = query.Where(e => e.SubCategoryId == subCategoryId.Value);
+        // Category filters now match against any line of the expense.
+        if (categoryGroupId.HasValue) query = query.Where(e => e.Lines.Any(l => l.CategoryGroupId == categoryGroupId.Value));
+        if (subCategoryId.HasValue)   query = query.Where(e => e.Lines.Any(l => l.SubCategoryId == subCategoryId.Value));
         // `statuses` (comma-separated) takes precedence over single `status`; lets the dashboard
         // request the Paid+Approved set in one call.
         if (!string.IsNullOrWhiteSpace(statuses))
@@ -81,23 +82,36 @@ public class ExpenseService : IExpenseService
 
         var minNames = await _db.Ministries.AsNoTracking().ToDictionaryAsync(m => m.Id, m => $"{m.Name_en} / {m.Name_zh}");
         var grpNames = await _db.ExpenseCategoryGroups.AsNoTracking().ToDictionaryAsync(g => g.Id, g => $"{g.Name_en} / {g.Name_zh}");
-        var subNames = await _db.ExpenseSubCategories.AsNoTracking().ToDictionaryAsync(s => s.Id, s => $"{s.Name_en} / {s.Name_zh}");
         var memberIds = rows.Where(r => r.MemberId != null).Select(r => r.MemberId!.Value).ToHashSet();
         var memNames = await _db.Members.AsNoTracking().Where(m => memberIds.Contains(m.Id))
             .ToDictionaryAsync(m => m.Id, m => $"{m.FirstName_en} {m.LastName_en}");
 
-        var items = rows.Select(e => new ExpenseListItemDto
+        // Line count + first line's category, per expense on this page.
+        var expenseIds = rows.Select(r => r.Id).ToList();
+        var lineRows = await _db.ExpenseLines.AsNoTracking()
+            .Where(l => expenseIds.Contains(l.ExpenseId))
+            .OrderBy(l => l.Id)
+            .Select(l => new { l.ExpenseId, l.CategoryGroupId })
+            .ToListAsync();
+        var linesByExpense = lineRows.GroupBy(l => l.ExpenseId)
+            .ToDictionary(g => g.Key, g => g.ToList());
+
+        var items = rows.Select(e =>
         {
-            Id = e.Id, Type = e.Type, Status = e.Status, Amount = e.Amount, Description = e.Description,
-            MinistryId = e.MinistryId, MinistryName = minNames.GetValueOrDefault(e.MinistryId, ""),
-            CategoryGroupId = e.CategoryGroupId, CategoryGroupName = grpNames.GetValueOrDefault(e.CategoryGroupId, ""),
-            SubCategoryId = e.SubCategoryId, SubCategoryName = subNames.GetValueOrDefault(e.SubCategoryId, ""),
-            VendorName = e.VendorName, MemberId = e.MemberId,
-            MemberName = e.MemberId != null ? memNames.GetValueOrDefault(e.MemberId.Value) : null,
-            ExpenseDate = e.ExpenseDate.ToString("yyyy-MM-dd"),
-            HasReceipt = e.ReceiptBlobPath != null,
-            CheckNumber = e.CheckNumber,
-            FunctionalClass = e.FunctionalClass,
+            linesByExpense.TryGetValue(e.Id, out var ls);
+            var firstGroupId = ls is { Count: > 0 } ? ls[0].CategoryGroupId : 0;
+            return new ExpenseListItemDto
+            {
+                Id = e.Id, Type = e.Type, Status = e.Status, Amount = e.Amount, Description = e.Description,
+                MinistryId = e.MinistryId, MinistryName = minNames.GetValueOrDefault(e.MinistryId, ""),
+                LineCount = ls?.Count ?? 0,
+                PrimaryCategoryName = grpNames.GetValueOrDefault(firstGroupId, ""),
+                VendorName = e.VendorName, MemberId = e.MemberId,
+                MemberName = e.MemberId != null ? memNames.GetValueOrDefault(e.MemberId.Value) : null,
+                ExpenseDate = e.ExpenseDate.ToString("yyyy-MM-dd"),
+                HasReceipt = e.ReceiptBlobPath != null,
+                CheckNumber = e.CheckNumber,
+            };
         }).ToList();
 
         return new PagedResult<ExpenseListItemDto> { Items = items, TotalCount = total, Page = page, PageSize = pageSize };
@@ -108,33 +122,66 @@ public class ExpenseService : IExpenseService
         var e = await _db.Expenses.AsNoTracking().FirstOrDefaultAsync(x => x.Id == id);
         if (e is null) return null;
         var minName = await _db.Ministries.Where(m => m.Id == e.MinistryId).Select(m => m.Name_en).FirstOrDefaultAsync() ?? "";
-        var grpName = await _db.ExpenseCategoryGroups.Where(g => g.Id == e.CategoryGroupId).Select(g => g.Name_en).FirstOrDefaultAsync() ?? "";
-        var subName = await _db.ExpenseSubCategories.Where(s => s.Id == e.SubCategoryId).Select(s => s.Name_en).FirstOrDefaultAsync() ?? "";
         string? memName = e.MemberId != null
             ? await _db.Members.Where(m => m.Id == e.MemberId).Select(m => m.FirstName_en + " " + m.LastName_en).FirstOrDefaultAsync()
             : null;
+
+        var lines = await _db.ExpenseLines.AsNoTracking().Where(l => l.ExpenseId == id).OrderBy(l => l.Id).ToListAsync();
+        var grpNames = await _db.ExpenseCategoryGroups.AsNoTracking().ToDictionaryAsync(g => g.Id, g => g.Name_en);
+        var subNames = await _db.ExpenseSubCategories.AsNoTracking().ToDictionaryAsync(s => s.Id, s => s.Name_en);
+        var lineDtos = lines.Select(l => new ExpenseLineItemDto
+        {
+            Id = l.Id, CategoryGroupId = l.CategoryGroupId, CategoryGroupName = grpNames.GetValueOrDefault(l.CategoryGroupId, ""),
+            SubCategoryId = l.SubCategoryId, SubCategoryName = subNames.GetValueOrDefault(l.SubCategoryId, ""),
+            FunctionalClass = l.FunctionalClass, Amount = l.Amount, Description = l.Description,
+        }).ToList();
+
         return new ExpenseDto
         {
             Id = e.Id, Type = e.Type, Status = e.Status, Amount = e.Amount, Description = e.Description,
             MinistryId = e.MinistryId, MinistryName = minName,
-            CategoryGroupId = e.CategoryGroupId, CategoryGroupName = grpName,
-            SubCategoryId = e.SubCategoryId, SubCategoryName = subName,
+            LineCount = lineDtos.Count,
+            PrimaryCategoryName = lineDtos.Count > 0 ? lineDtos[0].CategoryGroupName : "",
             VendorName = e.VendorName, MemberId = e.MemberId, MemberName = memName,
             ExpenseDate = e.ExpenseDate.ToString("yyyy-MM-dd"), HasReceipt = e.ReceiptBlobPath != null,
             CheckNumber = e.CheckNumber, Notes = e.Notes, ReviewNotes = e.ReviewNotes,
             SubmittedBy = e.SubmittedBy, SubmittedAt = e.SubmittedAt, ReviewedAt = e.ReviewedAt, PaidAt = e.PaidAt,
-            FunctionalClass = e.FunctionalClass,
+            Lines = lineDtos,
         };
     }
 
+    // Lines are the source of truth: ≥1 line, each with a category/subcategory and a positive amount.
+    private static void ValidateLines(List<ExpenseLineInput> lines)
+    {
+        if (lines is null || lines.Count == 0)
+            throw new InvalidOperationException("An expense must have at least one line.");
+        foreach (var l in lines)
+        {
+            if (l.CategoryGroupId <= 0 || l.SubCategoryId <= 0)
+                throw new InvalidOperationException("Each expense line needs a category group and subcategory.");
+            if (l.Amount <= 0)
+                throw new InvalidOperationException("Each expense line amount must be greater than zero.");
+            if (l.FunctionalClass is not null && !FunctionalClasses.All.Contains(l.FunctionalClass))
+                throw new InvalidOperationException($"Invalid functional class '{l.FunctionalClass}'.");
+        }
+    }
+
+    private static List<ExpenseLine> BuildLines(List<ExpenseLineInput> inputs) =>
+        inputs.Select(l => new ExpenseLine
+        {
+            CategoryGroupId = l.CategoryGroupId, SubCategoryId = l.SubCategoryId,
+            FunctionalClass = l.FunctionalClass, Amount = l.Amount, Description = l.Description,
+        }).ToList();
+
     public async Task<int> CreateAsync(CreateExpenseRequest r, bool isFinance)
     {
+        ValidateLines(r.Lines);
         var e = new Expense
         {
-            MinistryId = r.MinistryId, CategoryGroupId = r.CategoryGroupId, SubCategoryId = r.SubCategoryId,
-            Type = r.Type, Amount = r.Amount, Description = r.Description, VendorName = r.VendorName,
+            MinistryId = r.MinistryId,
+            Type = r.Type, Amount = r.Lines.Sum(l => l.Amount), Description = r.Description, VendorName = r.VendorName,
             CheckNumber = r.CheckNumber, ExpenseDate = r.ExpenseDate, Notes = r.Notes,
-            FunctionalClass = r.FunctionalClass,
+            Lines = BuildLines(r.Lines),
         };
 
         if (r.Type == "VendorPayment")
@@ -174,16 +221,21 @@ public class ExpenseService : IExpenseService
 
     public async Task UpdateAsync(int id, UpdateExpenseRequest r, bool isFinance)
     {
+        ValidateLines(r.Lines);
         // FirstOrDefaultAsync (not FindAsync) so the soft-delete query filter applies.
-        var e = await _db.Expenses.FirstOrDefaultAsync(x => x.Id == id)
+        var e = await _db.Expenses.Include(x => x.Lines).FirstOrDefaultAsync(x => x.Id == id)
             ?? throw new KeyNotFoundException($"Expense {id} not found.");
         if (!isFinance && !(e.SubmittedBy == CurrentUserId && (e.Status == "Draft" || e.Status == "PendingApproval")))
             throw new InvalidOperationException("You can only edit your own draft or pending reimbursements.");
 
-        e.MinistryId = r.MinistryId; e.CategoryGroupId = r.CategoryGroupId; e.SubCategoryId = r.SubCategoryId;
-        e.Amount = r.Amount; e.Description = r.Description; e.CheckNumber = r.CheckNumber;
-        e.ExpenseDate = r.ExpenseDate; e.Notes = r.Notes; e.FunctionalClass = r.FunctionalClass;
+        e.MinistryId = r.MinistryId; e.Description = r.Description; e.CheckNumber = r.CheckNumber;
+        e.ExpenseDate = r.ExpenseDate; e.Notes = r.Notes;
         if (e.Type == "VendorPayment") e.VendorName = r.VendorName;
+
+        // Replace the line set wholesale (lines are owned by the header), recompute the total.
+        _db.ExpenseLines.RemoveRange(e.Lines);
+        e.Lines = BuildLines(r.Lines);
+        e.Amount = r.Lines.Sum(l => l.Amount);
         await _db.SaveChangesAsync();
     }
 

API/ROLAC.API/Services/FinanceDashboardService.cs

@@ -53,17 +53,24 @@ public class FinanceDashboardService : IFinanceDashboardService
         DateOnly? from, DateOnly? to, int? ministryId, int? categoryGroupId)
     {
         var q = PaidApproved(from, to);
-        if (ministryId.HasValue)      q = q.Where(e => e.MinistryId == ministryId.Value);
-        if (categoryGroupId.HasValue) q = q.Where(e => e.CategoryGroupId == categoryGroupId.Value);
+        if (ministryId.HasValue) q = q.Where(e => e.MinistryId == ministryId.Value);
 
-        // Group by the deepest level whose parent id is supplied.
+        // Lines belonging to the scoped (Paid+Approved, optionally ministry-filtered) expenses.
+        var scopedLines = from l in _db.ExpenseLines
+                          join e in q on l.ExpenseId equals e.Id
+                          select l;
+
+        // Group by the deepest level whose parent id is supplied. Category levels aggregate
+        // over LINES (line amounts); the ministry level uses the header total to avoid
+        // double-counting a multi-line expense across its lines.
         List<(int Id, decimal Amount)> grouped;
         if (categoryGroupId.HasValue)
-            grouped = (await q.GroupBy(e => e.SubCategoryId)
+            grouped = (await scopedLines.Where(l => l.CategoryGroupId == categoryGroupId.Value)
+                .GroupBy(l => l.SubCategoryId)
                 .Select(g => new { Id = g.Key, Amount = g.Sum(x => x.Amount) }).ToListAsync())
                 .Select(x => (x.Id, x.Amount)).ToList();
         else if (ministryId.HasValue)
-            grouped = (await q.GroupBy(e => e.CategoryGroupId)
+            grouped = (await scopedLines.GroupBy(l => l.CategoryGroupId)
                 .Select(g => new { Id = g.Key, Amount = g.Sum(x => x.Amount) }).ToListAsync())
                 .Select(x => (x.Id, x.Amount)).ToList();
         else

API/ROLAC.API/Services/Form990ReportService.cs

@@ -8,7 +8,7 @@ namespace ROLAC.API.Services;
 /// <summary>
 /// Read-only aggregation that produces the IRS Form 990 Part IX Statement of Functional
 /// Expenses. Expense scope matches FinanceDashboardService: Paid + Approved only.
-/// Single function per expense (direct-charge); no cost splitting.
+/// Each expense line is categorized independently, so one invoice can span multiple lines.
 /// </summary>
 public class Form990ReportService : IForm990ReportService
 {
@@ -40,13 +40,14 @@ public class Form990ReportService : IForm990ReportService
 
         var rows = await (
             from e in expenses
+            join l   in _db.ExpenseLines           on e.Id              equals l.ExpenseId
             join m   in _db.Ministries            on e.MinistryId      equals m.Id
-            join sub in _db.ExpenseSubCategories   on e.SubCategoryId   equals sub.Id
-            join grp in _db.ExpenseCategoryGroups  on e.CategoryGroupId equals grp.Id
+            join sub in _db.ExpenseSubCategories   on l.SubCategoryId   equals sub.Id
+            join grp in _db.ExpenseCategoryGroups  on l.CategoryGroupId equals grp.Id
             select new
             {
-                e.Amount,
-                e.FunctionalClass,
+                l.Amount,
+                l.FunctionalClass,
                 MinistryDefault = m.DefaultFunctionalClass,
                 SubLineId   = sub.Form990LineId,
                 GroupLineId = grp.Form990LineId,