feat(audit): M5.5 per-channel retention overrides via purge-role bounded delete (T3)

src/ZB.MOM.WW.ScadaBridge.AuditLog/Configuration/AuditLogOptionsValidator.cs

@@ -1,4 +1,5 @@
 using ZB.MOM.WW.Configuration;
+using ZB.MOM.WW.ScadaBridge.Commons.Types.Enums;
 
 namespace ZB.MOM.WW.ScadaBridge.AuditLog.Configuration;
 
@@ -52,5 +53,27 @@ public sealed class AuditLogOptionsValidator : OptionsValidatorBase<AuditLogOpti
             !(options.InboundMaxBytes < MinInboundMaxBytes || options.InboundMaxBytes > MaxInboundMaxBytes),
             $"AuditLog:{nameof(AuditLogOptions.InboundMaxBytes)} ({options.InboundMaxBytes}) " +
             $"must be in [{MinInboundMaxBytes}, {MaxInboundMaxBytes}] bytes.");
+
+        // M5.5 (T3): per-channel retention overrides. Each entry must be keyed by a
+        // recognized AuditChannel name and carry a window in [MinRetentionDays,
+        // RetentionDays] — i.e. SHORTER than or equal to the global window. A longer
+        // per-channel window is meaningless under month-partition switch-out (governed
+        // by the global window), so it is rejected rather than silently ignored.
+        foreach (var (channelKey, days) in options.PerChannelRetentionDays)
+        {
+            builder.RequireThat(
+                Enum.TryParse<AuditChannel>(channelKey, ignoreCase: false, out _),
+                $"AuditLog:{nameof(AuditLogOptions.PerChannelRetentionDays)} key '{channelKey}' " +
+                $"is not a recognized channel name. Valid keys: {string.Join(", ", Enum.GetNames<AuditChannel>())}.");
+
+            // Valid when days is within [MinRetentionDays, RetentionDays] inclusive.
+            // The lower bound matches the global RetentionDays floor; the upper bound
+            // is the configured global window (longer is meaningless — see remarks).
+            builder.RequireThat(
+                !(days < MinRetentionDays || days > options.RetentionDays),
+                $"AuditLog:{nameof(AuditLogOptions.PerChannelRetentionDays)}['{channelKey}'] ({days}) " +
+                $"must be in [{MinRetentionDays}, {nameof(AuditLogOptions.RetentionDays)}={options.RetentionDays}] days " +
+                "— a per-channel window must be shorter than or equal to the global retention window.");
+        }
     }
 }