diff --git a/src/ZB.MOM.WW.ScadaBridge.AuditLog/Site/SiteAuditRetentionOptions.cs b/src/ZB.MOM.WW.ScadaBridge.AuditLog/Site/SiteAuditRetentionOptions.cs
new file mode 100644
index 00000000..3aee06a9
--- /dev/null
+++ b/src/ZB.MOM.WW.ScadaBridge.AuditLog/Site/SiteAuditRetentionOptions.cs
@@ -0,0 +1,60 @@
+namespace ZB.MOM.WW.ScadaBridge.AuditLog.Site;
+
+/// <summary>
+/// Configuration for the site-side SQLite retention purge (PLAN-04 Task 2, S1/U2).
+/// The site audit store is ephemeral (~7-day retention); <see cref="SiteAuditRetentionService"/>
+/// runs <see cref="ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Services.ISiteAuditQueue.PurgeExpiredAsync"/>
+/// on a timer using these knobs. Mirrors the resolve/clamp shape of
+/// <c>SiteCallAuditOptions</c> so a misconfigured value can never make the timer spin
+/// or the retention window collapse.
+/// </summary>
+public class SiteAuditRetentionOptions
+{
+    /// <summary>Configuration section path bound in the site host.</summary>
+    public const string SectionName = "ScadaBridge:AuditLog:SiteRetention";
+
+    /// <summary>
+    /// Retention window in days. On each purge tick, Forwarded/Reconciled rows whose
+    /// <c>OccurredAtUtc</c> is older than <c>UtcNow - ResolvedRetentionDays</c> are
+    /// deleted (Pending rows are never purged on age alone). Default 7. Resolved value
+    /// is clamped to <see cref="MinRetentionDays"/>..<see cref="MaxRetentionDays"/>.
+    /// </summary>
+    public int RetentionDays { get; set; } = 7;
+
+    private const int MinRetentionDays = 1;
+    private const int MaxRetentionDays = 90;
+
+    /// <summary>
+    /// Effective retention window: <see cref="RetentionDays"/> clamped to
+    /// [<see cref="MinRetentionDays"/>, <see cref="MaxRetentionDays"/>] so a
+    /// misconfigured 0 (which would purge everything) or an unbounded value can
+    /// never take effect.
+    /// </summary>
+    public int ResolvedRetentionDays =>
+        RetentionDays < MinRetentionDays ? MinRetentionDays
+        : RetentionDays > MaxRetentionDays ? MaxRetentionDays
+        : RetentionDays;
+
+    /// <summary>
+    /// Period of the purge tick. Default 24 hours. Resolved value is clamped to at
+    /// least <see cref="MinPurgeInterval"/> so a zero/negative config value cannot
+    /// make the timer fire in a tight loop.
+    /// </summary>
+    public TimeSpan PurgeInterval { get; set; } = TimeSpan.FromHours(24);
+
+    private static readonly TimeSpan MinPurgeInterval = TimeSpan.FromMinutes(1);
+
+    /// <summary>
+    /// Effective purge period: <see cref="PurgeInterval"/> clamped to at least
+    /// <see cref="MinPurgeInterval"/> (the Timer/Akka zero-interval spin footgun).
+    /// </summary>
+    public TimeSpan ResolvedPurgeInterval =>
+        PurgeInterval < MinPurgeInterval ? MinPurgeInterval : PurgeInterval;
+
+    /// <summary>
+    /// Delay before the first purge tick. Default 5 minutes — short so a node that
+    /// restarts daily (or more often) still runs the purge shortly after start
+    /// rather than waiting a full <see cref="PurgeInterval"/> it may never reach.
+    /// </summary>
+    public TimeSpan InitialDelay { get; set; } = TimeSpan.FromMinutes(5);
+}
diff --git a/tests/ZB.MOM.WW.ScadaBridge.AuditLog.Tests/Site/SiteAuditRetentionOptionsTests.cs b/tests/ZB.MOM.WW.ScadaBridge.AuditLog.Tests/Site/SiteAuditRetentionOptionsTests.cs
new file mode 100644
index 00000000..da9d66da
--- /dev/null
+++ b/tests/ZB.MOM.WW.ScadaBridge.AuditLog.Tests/Site/SiteAuditRetentionOptionsTests.cs
@@ -0,0 +1,33 @@
+using ZB.MOM.WW.ScadaBridge.AuditLog.Site;
+
+namespace ZB.MOM.WW.ScadaBridge.AuditLog.Tests.Site;
+
+/// <summary>
+/// Tests for <see cref="SiteAuditRetentionOptions"/> clamping (PLAN-04 Task 2).
+/// The resolved knobs guard the daily site retention job against misconfiguration:
+/// retention days are clamped to [1, 90]; the purge interval is clamped away from
+/// TimeSpan.Zero (an Akka/Timer spin footgun).
+/// </summary>
+public class SiteAuditRetentionOptionsTests
+{
+    [Theory]
+    [InlineData(0, 1)]     // clamp floor
+    [InlineData(7, 7)]     // default passthrough
+    [InlineData(365, 90)]  // clamp ceiling (spec: min 1, max 90)
+    public void ResolvedRetentionDays_Clamps(int configured, int expected)
+        => Assert.Equal(expected, new SiteAuditRetentionOptions { RetentionDays = configured }.ResolvedRetentionDays);
+
+    [Fact]
+    public void Defaults_Are_SevenDays_DailyPurge_FiveMinuteInitialDelay()
+    {
+        var o = new SiteAuditRetentionOptions();
+        Assert.Equal(7, o.ResolvedRetentionDays);
+        Assert.Equal(TimeSpan.FromHours(24), o.ResolvedPurgeInterval);
+        Assert.Equal(TimeSpan.FromMinutes(5), o.InitialDelay);
+    }
+
+    [Fact]
+    public void ResolvedPurgeInterval_ClampsZeroToOneMinute()
+        => Assert.Equal(TimeSpan.FromMinutes(1),
+            new SiteAuditRetentionOptions { PurgeInterval = TimeSpan.Zero }.ResolvedPurgeInterval);
+}