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src/Graph/StellaOps.Graph.Indexer/Incremental/NoOpGraphChangeEventSource.cs

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+using System.Collections.Immutable;
+using System.Runtime.CompilerServices;
+using System.Text.Json.Nodes;
+
+namespace StellaOps.Graph.Indexer.Incremental;
+
+/// <summary>
+/// No-op change/backfill source used when no external change feed is configured.
+/// </summary>
+public sealed class NoOpGraphChangeEventSource : IGraphChangeEventSource, IGraphBackfillSource
+{
+    public IAsyncEnumerable<GraphChangeEvent> ReadAsync(CancellationToken cancellationToken) =>
+        ReadInternalAsync(cancellationToken);
+
+    public IAsyncEnumerable<GraphChangeEvent> ReadBackfillAsync(CancellationToken cancellationToken) =>
+        ReadInternalAsync(cancellationToken);
+
+    private static async IAsyncEnumerable<GraphChangeEvent> ReadInternalAsync([EnumeratorCancellation] CancellationToken cancellationToken)
+    {
+        await Task.CompletedTask.ConfigureAwait(false);
+        yield break;
+    }
+}