feat(auditlog): SiteAuditTelemetryActor + ISiteStreamAuditClient seam (#23)

src/ScadaLink.AuditLog/Site/Telemetry/ISiteAuditQueue.cs

@@ -0,0 +1,34 @@
+using ScadaLink.Commons.Entities.Audit;
+
+namespace ScadaLink.AuditLog.Site.Telemetry;
+
+/// <summary>
+/// Site-local audit-log queue surface consumed by <see cref="SiteAuditTelemetryActor"/>.
+/// Extracted from <see cref="SqliteAuditWriter"/> so the telemetry actor can be
+/// unit-tested against a stub without touching SQLite. <see cref="SqliteAuditWriter"/>
+/// implements this interface; production wiring injects the same instance.
+/// </summary>
+/// <remarks>
+/// Only the two methods the drain loop needs are exposed — the hot-path
+/// <c>WriteAsync</c> stays on <see cref="Commons.Interfaces.Services.IAuditWriter"/>
+/// (script-thread surface), separated by concern from the
+/// telemetry-actor surface so each side can be mocked independently.
+/// </remarks>
+public interface ISiteAuditQueue
+{
+    /// <summary>
+    /// Returns up to <paramref name="limit"/> rows currently in
+    /// <see cref="ScadaLink.Commons.Types.Enums.AuditForwardState.Pending"/>,
+    /// oldest first. Idempotent — repeated calls before
+    /// <see cref="MarkForwardedAsync"/> will yield the same rows again.
+    /// </summary>
+    Task<IReadOnlyList<AuditEvent>> ReadPendingAsync(int limit, CancellationToken ct = default);
+
+    /// <summary>
+    /// Flips the supplied EventIds from
+    /// <see cref="ScadaLink.Commons.Types.Enums.AuditForwardState.Pending"/> to
+    /// <see cref="ScadaLink.Commons.Types.Enums.AuditForwardState.Forwarded"/>.
+    /// Non-existent or already-forwarded ids are silent no-ops.
+    /// </summary>
+    Task MarkForwardedAsync(IReadOnlyList<Guid> eventIds, CancellationToken ct = default);
+}