diff --git a/model/interactive/src/main/proto/beam_interactive_api.proto b/model/interactive/src/main/proto/beam_interactive_api.proto
index 91c89c88708c..e9136cb11ff0 100644
--- a/model/interactive/src/main/proto/beam_interactive_api.proto
+++ b/model/interactive/src/main/proto/beam_interactive_api.proto
@@ -46,14 +46,6 @@ message TestStreamFileHeader {
 // give enough information to create a faithful recreation of the original
 // stream of data.
 message TestStreamFileRecord {
-  oneof recorded_event {
-    // The recorded element with its event timestamp (when it was produced).
-    org.apache.beam.model.pipeline.v1.TestStreamPayload.TimestampedElement element = 1;
-
-    // Indicating the output watermark of the source changed.
-    google.protobuf.Timestamp watermark = 2;
-  }
-
-  // The wall-time timestamp of either the new element or watermark change.
-  google.protobuf.Timestamp processing_time = 3;
+  // The recorded event from an element stream.
+  org.apache.beam.model.pipeline.v1.TestStreamPayload.Event recorded_event = 1;
 }
diff --git a/model/pipeline/src/main/proto/beam_runner_api.proto b/model/pipeline/src/main/proto/beam_runner_api.proto
index 5439bc008c10..050fc070c925 100644
--- a/model/pipeline/src/main/proto/beam_runner_api.proto
+++ b/model/pipeline/src/main/proto/beam_runner_api.proto
@@ -576,7 +576,14 @@ service TestStreamService {
   // A TestStream will request for events using this RPC.
   rpc Events(EventsRequest) returns (stream TestStreamPayload.Event) {}
 }
-message EventsRequest {}
+
+message EventsRequest {
+  // The set of PCollections to read from. These are the PTransform outputs
+  // local names. These are a subset of the TestStream's outputs. This allows
+  // Interactive Beam to cache many PCollections from a pipeline then replay a
+  // subset of them.
+  repeated string output_ids = 1;
+}
 
 // The payload for the special-but-not-primitive WriteFiles transform.
 message WriteFilesPayload {