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src/PowderCoating.Infrastructure/Services/PlatformSettingsService.cs

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+using Microsoft.EntityFrameworkCore;
+using PowderCoating.Application.Interfaces;
+using PowderCoating.Core.Entities;
+using PowderCoating.Infrastructure.Data;
+
+namespace PowderCoating.Infrastructure.Services;
+
+/// <summary>
+/// Database-backed key/value store for platform-wide configuration settings managed by
+/// SuperAdmins at <c>/PlatformSettings</c>. Settings are persisted in the <c>PlatformSettings</c>
+/// table as free-form strings; callers are responsible for parsing typed values (booleans, ints,
+/// etc.) from the returned strings. Rows are seeded at startup so that every expected key always
+/// has a row — the <see cref="SetAsync"/> guard that inserts a missing row is a safety net for
+/// future migrations, not the normal path.
+/// </summary>
+public class PlatformSettingsService : IPlatformSettingsService
+{
+    private readonly ApplicationDbContext _db;
+
+    /// <summary>
+    /// Constructs the service with a direct <see cref="ApplicationDbContext"/> reference.
+    /// Direct context access is used (rather than a repository) because
+    /// <c>PlatformSetting</c> does not inherit <c>BaseEntity</c> and therefore is not managed
+    /// by the generic <c>Repository&lt;T&gt;</c> or filtered by the global query filters.
+    /// </summary>
+    public PlatformSettingsService(ApplicationDbContext db)
+    {
+        _db = db;
+    }
+
+    /// <summary>
+    /// Retrieves the value for the given <paramref name="key"/>, or <c>null</c> when the key
+    /// does not exist. Uses <c>AsNoTracking</c> because reads are more frequent than writes and
+    /// the caller never modifies the returned value directly.
+    /// </summary>
+    public async Task<string?> GetAsync(string key)
+    {
+        var setting = await _db.PlatformSettings
+            .AsNoTracking()
+            .FirstOrDefaultAsync(s => s.Key == key);
+        return setting?.Value;
+    }
+
+    /// <summary>
+    /// Creates or updates the platform setting identified by <paramref name="key"/>.
+    /// Records <paramref name="updatedBy"/> (typically the SuperAdmin's username) and
+    /// <c>UpdatedAt</c> (UTC) for audit purposes. Inserts a new row if the key is missing —
+    /// this should only happen when a new setting key is introduced without a corresponding
+    /// seed migration. Calls <c>SaveChangesAsync</c> directly rather than going through
+    /// <c>IUnitOfWork</c> to avoid inadvertently flushing unrelated tracked changes from the
+    /// caller's scope.
+    /// </summary>
+    public async Task SetAsync(string key, string? value, string? updatedBy = null)
+    {
+        var setting = await _db.PlatformSettings.FirstOrDefaultAsync(s => s.Key == key);
+        if (setting == null)
+        {
+            // Shouldn't happen in normal use (rows are seeded), but handle gracefully
+            setting = new PlatformSetting { Key = key };
+            _db.PlatformSettings.Add(setting);
+        }
+
+        setting.Value = value;
+        setting.UpdatedAt = DateTime.UtcNow;
+        setting.UpdatedBy = updatedBy;
+
+        await _db.SaveChangesAsync();
+    }
+
+    /// <summary>
+    /// Returns all platform settings ordered by group then key, suitable for rendering the
+    /// SuperAdmin settings management UI. Results are read with <c>AsNoTracking</c> for
+    /// performance; the UI renders them read-only and individual edits go through
+    /// <see cref="SetAsync"/>.
+    /// </summary>
+    public async Task<IReadOnlyList<PlatformSetting>> GetAllAsync()
+    {
+        return await _db.PlatformSettings
+            .AsNoTracking()
+            .OrderBy(s => s.GroupName)
+            .ThenBy(s => s.Key)
+            .ToListAsync();
+    }
+}