Refactor GL period and entry date handling to use BusinessClock for accurate date resolution; add GlAccountCodeValidator for startup validation of configured account codes.

Backend/ERPCore/Services/AdjustmentService.cs

@@ -9,6 +9,7 @@ using ERPCore.Repositories.Interfaces;
 using ERPCore.Services.Gl;
 using ERPCore.Services.Interfaces;
 using ERPCore.System.Errors;
+using ERPCore.System.Time;
 using Microsoft.EntityFrameworkCore;
 
 namespace ERPCore.Services;
@@ -73,7 +74,7 @@ public sealed class AdjustmentService : IAdjustmentService
         var loss = refs.Where(r => r.Direction == Direction.Out).Sum(r => r.Value);
         if (gain <= 0 && loss <= 0) return null;
 
-        var period = await _gl.GetPeriodByDateAsync(DateOnly.FromDateTime(now), ct);
+        var period = await _gl.GetPeriodByDateAsync(BusinessClock.ToBusinessDate(now), ct);
         var lines = new List<GlJournalEntryLineRequest>();
         if (gain > 0)
         {
@@ -89,7 +90,7 @@ public sealed class AdjustmentService : IAdjustmentService
         var result = await _gl.PostJournalEntryAsync(new GlJournalEntryRequest
         {
             PeriodId = period.PeriodId,
-            EntryDate = DateOnly.FromDateTime(now),
+            EntryDate = BusinessClock.ToBusinessDate(now),
             SourceModule = "ADJUSTMENT",
             Reference = docNo,
             Narration = $"Stock adjustment {docNo}",

Backend/ERPCore/Services/CountService.cs

@@ -9,6 +9,7 @@ using ERPCore.Repositories.Interfaces;
 using ERPCore.Services.Gl;
 using ERPCore.Services.Interfaces;
 using ERPCore.System.Errors;
+using ERPCore.System.Time;
 using Microsoft.EntityFrameworkCore;
 
 namespace ERPCore.Services;
@@ -80,7 +81,7 @@ public sealed class CountService : ICountService
         var loss = refs.Where(r => r.Direction == Direction.Out).Sum(r => r.Value);
         if (gain <= 0 && loss <= 0) return null;
 
-        var period = await _gl.GetPeriodByDateAsync(DateOnly.FromDateTime(now), ct);
+        var period = await _gl.GetPeriodByDateAsync(BusinessClock.ToBusinessDate(now), ct);
         var lines = new List<GlJournalEntryLineRequest>();
         if (gain > 0)
         {
@@ -96,7 +97,7 @@ public sealed class CountService : ICountService
         var result = await _gl.PostJournalEntryAsync(new GlJournalEntryRequest
         {
             PeriodId = period.PeriodId,
-            EntryDate = DateOnly.FromDateTime(now),
+            EntryDate = BusinessClock.ToBusinessDate(now),
             SourceModule = "ADJUSTMENT",
             Reference = docNo,
             Narration = $"Stock adjustment {docNo}",

Backend/ERPCore/Services/GeneralLedgerService.cs

@@ -49,6 +49,19 @@ public sealed class GeneralLedgerService : IGeneralLedgerService
             a.CashAccountTypeName, a.AccountNumber, a.GlAccountId, a.GlAccountCode, a.CurrencyCode)).ToList();
     }
 
+    public async Task<HashSet<string>> ListAccountCodesAsync(CancellationToken ct)
+    {
+        // No page/pageSize: GL pages this endpoint only when both are supplied, so this is the
+        // full, flat chart of accounts (child codes like "1000-01" are rows of their own —
+        // `parentAccountId` is a field, not a nested `children` array).
+        var response = await _client.SendAsync(HttpMethod.Get, "accounts", null, null, null, ct);
+        var data = ParseSuccess<GlAccountListData>(response);
+        return data.Items
+            .Select(a => a.AccountCode)
+            .Where(c => !string.IsNullOrWhiteSpace(c))
+            .ToHashSet(StringComparer.Ordinal);
+    }
+
     /// <summary>
     /// Parses GL's <c>ApiResponse</c> envelope (case-insensitively, since GL's success bodies are
     /// camelCase and its error bodies are PascalCase — docs/12 §4) and throws
@@ -96,6 +109,16 @@ public sealed class GeneralLedgerService : IGeneralLedgerService
         public int FiscalYearId { get; set; }
     }
 
+    private sealed class GlAccountListData
+    {
+        public List<GlAccountData> Items { get; set; } = [];
+    }
+
+    private sealed class GlAccountData
+    {
+        public string AccountCode { get; set; } = string.Empty;
+    }
+
     private sealed class GlBankAccountData
     {
         public string AccountType { get; set; } = string.Empty;

Backend/ERPCore/Services/GrnService.cs

@@ -9,6 +9,7 @@ using ERPCore.Repositories.Interfaces;
 using ERPCore.Services.Gl;
 using ERPCore.Services.Interfaces;
 using ERPCore.System.Errors;
+using ERPCore.System.Time;
 using Microsoft.EntityFrameworkCore;
 
 namespace ERPCore.Services;
@@ -310,7 +311,7 @@ public sealed class GrnService : IGrnService
             // with it, so inventory and the ledger never diverge (user-approved "fails
             // atomically" behavior; residual risk if GL posts but the local commit still
             // fails afterward is accepted for this phase, see the integration plan).
-            var period = await _gl.GetPeriodByDateAsync(DateOnly.FromDateTime(now), token);
+            var period = await _gl.GetPeriodByDateAsync(BusinessClock.ToBusinessDate(now), token);
             var glLines = new List<GlJournalEntryLineRequest>();
             decimal totalPayable = 0m;
             foreach (var line in grn.Lines.OrderBy(l => l.GrnLineId))
@@ -325,7 +326,7 @@ public sealed class GrnService : IGrnService
             var posted = await _gl.PostJournalEntryAsync(new GlJournalEntryRequest
             {
                 PeriodId = period.PeriodId,
-                EntryDate = DateOnly.FromDateTime(now),
+                EntryDate = BusinessClock.ToBusinessDate(now),
                 SourceModule = "GRN",
                 Reference = grn.DocNo,
                 Narration = $"Goods received - GRN {grn.DocNo}",

Backend/ERPCore/Services/Interfaces/IGeneralLedgerService.cs

@@ -24,4 +24,10 @@ public interface IGeneralLedgerService
 
     /// <summary>Lists GL's cash and bank accounts (default: both types).</summary>
     Task<IReadOnlyList<GlBankAccount>> ListBankAccountsAsync(CancellationToken ct);
+
+    /// <summary>
+    /// Every account code in GL's chart of accounts. Used at startup to verify the configured
+    /// <c>Gl*Code</c> settings exist — see <see cref="ERPCore.Infra.Gl.GlAccountCodeValidator"/>.
+    /// </summary>
+    Task<HashSet<string>> ListAccountCodesAsync(CancellationToken ct);
 }

Backend/ERPCore/Services/PurchaseInvoicePaymentService.cs

@@ -7,6 +7,7 @@ using ERPCore.Repositories.Interfaces;
 using ERPCore.Services.Gl;
 using ERPCore.Services.Interfaces;
 using ERPCore.System.Errors;
+using ERPCore.System.Time;
 using Microsoft.EntityFrameworkCore;
 
 namespace ERPCore.Services;
@@ -61,11 +62,11 @@ public sealed class PurchaseInvoicePaymentService : IPurchaseInvoicePaymentServi
 
         var payment = await _uow.ExecuteInTransactionAsync(async token =>
         {
-            var period = await _gl.GetPeriodByDateAsync(DateOnly.FromDateTime(now), token);
+            var period = await _gl.GetPeriodByDateAsync(BusinessClock.ToBusinessDate(now), token);
             var posted = await _gl.PostJournalEntryAsync(new GlJournalEntryRequest
             {
                 PeriodId = period.PeriodId,
-                EntryDate = DateOnly.FromDateTime(now),
+                EntryDate = BusinessClock.ToBusinessDate(now),
                 SourceModule = "PURCHASE_INVOICE_PAYMENT",
                 Reference = invoice.DocNo,
                 Narration = $"Payment against invoice {invoice.DocNo}",

Backend/ERPCore/Services/PurchaseInvoiceService.cs

@@ -11,6 +11,7 @@ using ERPCore.Repositories.Interfaces;
 using ERPCore.Services.Gl;
 using ERPCore.Services.Interfaces;
 using ERPCore.System.Errors;
+using ERPCore.System.Time;
 using Microsoft.EntityFrameworkCore;
 
 namespace ERPCore.Services;
@@ -185,11 +186,11 @@ public sealed class PurchaseInvoiceService : IPurchaseInvoiceService
             // Reclassify the GRN clearing balance to Accounts Payable — the mirror image of
             // SalesInvoicePaymentService's AR credit — before committing, so a GL rejection
             // rolls the whole post back (same atomicity approach as GrnService.ConfirmAsync).
-            var period = await _gl.GetPeriodByDateAsync(DateOnly.FromDateTime(now), token);
+            var period = await _gl.GetPeriodByDateAsync(BusinessClock.ToBusinessDate(now), token);
             var posted = await _gl.PostJournalEntryAsync(new GlJournalEntryRequest
             {
                 PeriodId = period.PeriodId,
-                EntryDate = DateOnly.FromDateTime(now),
+                EntryDate = BusinessClock.ToBusinessDate(now),
                 SourceModule = "PURCHASE_INVOICE",
                 Reference = invoice.DocNo,
                 Narration = $"Vendor invoice recognized - {invoice.DocNo}",

Backend/ERPCore/Services/PurchaseReturnService.cs

@@ -9,6 +9,7 @@ using ERPCore.Repositories.Interfaces;
 using ERPCore.Services.Gl;
 using ERPCore.Services.Interfaces;
 using ERPCore.System.Errors;
+using ERPCore.System.Time;
 using Microsoft.EntityFrameworkCore;
 
 namespace ERPCore.Services;
@@ -220,11 +221,11 @@ public sealed class PurchaseReturnService : IPurchaseReturnService
             var totalValue = refs.Sum(r => r.Value);
             if (totalValue > 0)
             {
-                var period = await _gl.GetPeriodByDateAsync(DateOnly.FromDateTime(now), token);
+                var period = await _gl.GetPeriodByDateAsync(BusinessClock.ToBusinessDate(now), token);
                 var glResult = await _gl.PostJournalEntryAsync(new GlJournalEntryRequest
                 {
                     PeriodId = period.PeriodId,
-                    EntryDate = DateOnly.FromDateTime(now),
+                    EntryDate = BusinessClock.ToBusinessDate(now),
                     SourceModule = "PURCHASE-RETURN",
                     Reference = docNo,
                     Narration = $"Purchase return {docNo} — stock returned to vendor",

Backend/ERPCore/Services/SalesInvoicePaymentService.cs

@@ -7,6 +7,7 @@ using ERPCore.Repositories.Interfaces;
 using ERPCore.Services.Gl;
 using ERPCore.Services.Interfaces;
 using ERPCore.System.Errors;
+using ERPCore.System.Time;
 using Microsoft.EntityFrameworkCore;
 
 namespace ERPCore.Services;
@@ -220,13 +221,15 @@ public sealed class SalesInvoicePaymentService : ISalesInvoicePaymentService
 
     /// <summary>
     /// The payment's calendar day (also the GL entry date) and the timestamp stored on it. Omitted ⇒
-    /// today. One day of slack on "future": the client sends its local date, which runs ahead of UTC
-    /// for users east of it. Today keeps the actual time of entry; a back-dated payment is stamped at
-    /// that day's start.
+    /// today — the <em>business</em> day (<see cref="BusinessClock"/>), not the UTC one, or a payment
+    /// taken between midnight and 05:30 local would post to the previous day and, on the 1st, to the
+    /// previous accounting period. The day of slack on "future" is kept as a tolerance for clients
+    /// whose own clock runs ahead. Today keeps the actual time of entry; a back-dated payment is
+    /// stamped at that day's start. The returned stamp stays UTC.
     /// </summary>
     private static (DateOnly Day, DateTime Stamp) ResolvePaymentDate(DateOnly? requested, DateTime now)
     {
-        var today = DateOnly.FromDateTime(now);
+        var today = BusinessClock.ToBusinessDate(now);
         var day = requested ?? today;
         if (day > today.AddDays(1))
             throw new DomainException(ErrorCodes.Validation, "Payment date cannot be in the future.", 400);

Backend/ERPCore/Services/SalesPostingService.cs

@@ -9,6 +9,7 @@ using ERPCore.Services.Gl;
 using ERPCore.Services.Interfaces;
 using ERPCore.Services.Stock;
 using ERPCore.System.Errors;
+using ERPCore.System.Time;
 using Microsoft.EntityFrameworkCore;
 
 namespace ERPCore.Services;
@@ -184,7 +185,7 @@ public sealed class SalesPostingService : ISalesPostingService
         if (invoice.NetPayable <= 0 && cogs <= 0) return;
 
         var now = DateTime.UtcNow;
-        var period = await _gl.GetPeriodByDateAsync(DateOnly.FromDateTime(now), ct);
+        var period = await _gl.GetPeriodByDateAsync(BusinessClock.ToBusinessDate(now), ct);
         var lines = new List<GlJournalEntryLineRequest>();
         if (invoice.NetPayable > 0)
         {
@@ -204,7 +205,7 @@ public sealed class SalesPostingService : ISalesPostingService
         var result = await _gl.PostJournalEntryAsync(new GlJournalEntryRequest
         {
             PeriodId = period.PeriodId,
-            EntryDate = DateOnly.FromDateTime(now),
+            EntryDate = BusinessClock.ToBusinessDate(now),
             SourceModule = "SALES_INVOICE",
             Reference = invoice.InvoiceNo,
             Narration = $"Sales invoice {invoice.InvoiceNo} posted",

Backend/ERPCore/Services/SalesReturnService.cs

@@ -9,6 +9,7 @@ using ERPCore.Repositories.Interfaces;
 using ERPCore.Services.Gl;
 using ERPCore.Services.Interfaces;
 using ERPCore.System.Errors;
+using ERPCore.System.Time;
 using Microsoft.EntityFrameworkCore;
 
 namespace ERPCore.Services;
@@ -179,11 +180,11 @@ public sealed class SalesReturnService : ISalesReturnService
             var totalValue = refs.Sum(r => r.Value);
             if (totalValue > 0)
             {
-                var period = await _gl.GetPeriodByDateAsync(DateOnly.FromDateTime(now), token);
+                var period = await _gl.GetPeriodByDateAsync(BusinessClock.ToBusinessDate(now), token);
                 var glResult = await _gl.PostJournalEntryAsync(new GlJournalEntryRequest
                 {
                     PeriodId = period.PeriodId,
-                    EntryDate = DateOnly.FromDateTime(now),
+                    EntryDate = BusinessClock.ToBusinessDate(now),
                     SourceModule = "SALES-RETURN",
                     Reference = docNo,
                     Narration = $"Sales return {docNo} — stock restocked",

Backend/ERPCore/Services/Stock/FifoCostingService.cs

@@ -6,6 +6,7 @@ using ERPCore.Repositories.Interfaces;
 using ERPCore.Services.Gl;
 using ERPCore.Services.Interfaces;
 using ERPCore.System.Errors;
+using ERPCore.System.Time;
 using Microsoft.EntityFrameworkCore;
 
 namespace ERPCore.Services.Stock;
@@ -289,11 +290,11 @@ public sealed class FifoCostingService : IFifoCostingService
 
         if (entry.Value != 0)
         {
-            var period = await _gl.GetPeriodByDateAsync(DateOnly.FromDateTime(createdAt), ct);
+            var period = await _gl.GetPeriodByDateAsync(BusinessClock.ToBusinessDate(createdAt), ct);
             await _gl.PostJournalEntryAsync(new GlJournalEntryRequest
             {
                 PeriodId = period.PeriodId,
-                EntryDate = DateOnly.FromDateTime(createdAt),
+                EntryDate = BusinessClock.ToBusinessDate(createdAt),
                 SourceModule = "STOCK",
                 Reference = $"{sourceDocType}#{sourceDocId}",
                 Narration = $"{sourceDocType} {sourceDocId} — {direction} {qtyBase} @ {unitCost}",