diff --git a/internal/events/event-relay.go b/internal/events/event-relay.go
index e4e11ce4..3ecdb201 100644
--- a/internal/events/event-relay.go
+++ b/internal/events/event-relay.go
@@ -83,12 +83,17 @@ func (r *analyticsEventEndpointDispatcher) dispatch(w http.ResponseWriter, req *
 		metadata := GetEventPayloadMetadata(req)
 
 		r.loggers.Debugf("Received %d events (v%d) to be proxied to %s", len(evts), metadata.SchemaVersion, r.remotePath)
-		if metadata.SchemaVersion >= SummaryEventsSchemaVersion {
-			// New-style events that have already gone through summarization - deliver them as-is
-			r.getVerbatimRelay().enqueue(metadata, evts)
-		} else {
+		if metadata.SchemaVersion < SummaryEventsSchemaVersion {
 			r.getSummarizingRelay().enqueue(metadata, evts)
+			return
+		}
+
+		if _, ok := req.Header[http.CanonicalHeaderKey(EventUnsummarizedHeader)]; ok {
+			r.getSummarizingRelay().enqueue(metadata, evts)
+			return
 		}
+
+		r.getVerbatimRelay().enqueue(metadata, evts)
 	})
 }
 
diff --git a/internal/events/event_constants.go b/internal/events/event_constants.go
index d04f2f70..5d6f0bec 100644
--- a/internal/events/event_constants.go
+++ b/internal/events/event_constants.go
@@ -10,6 +10,10 @@ const (
 	// EventSchemaHeader is an HTTP header that describes the schema version for event requests.
 	EventSchemaHeader = "X-LaunchDarkly-Event-Schema"
 
+	// EventUnsummarizedHeader is an HTTP header that denotes events being received have not gone
+	// through the standard event summarization process.
+	EventUnsummarizedHeader = "X-LaunchDarkly-Unsummarized"
+
 	// TagsHeader is an HTTP header that may be sent by SDKs that support application metadata.
 	// We copy the value of this header when proxying events.
 	TagsHeader = "X-LaunchDarkly-Tags"
diff --git a/internal/events/summarizing-relay-testdata_test.go b/internal/events/summarizing-relay-testdata_test.go
index c422b8a8..3fb8b57d 100644
--- a/internal/events/summarizing-relay-testdata_test.go
+++ b/internal/events/summarizing-relay-testdata_test.go
@@ -90,6 +90,28 @@ func makeAllSummarizeEventsParams() []summarizeEventsParams {
 				}
 			]`,
 		},
+		{
+			name:          "php feature event using schema 4 will be summarized",
+			schemaVersion: 4,
+			inputEventsJSON: `
+			[
+				{ "kind": "feature", "creationDate": 1000, "key": "flagkey", "user": {"key": "userkey"},
+				"value": "b", "default": "c", "version": 11, "variation": 1, "trackEvents": false, "samplingRatio": 1, "excludeFromSummaries": false }
+			]`,
+			expectedEventsJSON: `
+			[
+				{ "kind": "index", "creationDate": 1000, "context": {"key": "userkey"} },
+				{
+					"kind": "summary", "startDate": 1000, "endDate": 1000,
+					"features": {
+						"flagkey": {
+							"default": "c", "contextKinds": ["user"],
+							"counters": [{"variation": 1, "version": 11, "value": "b", "count": 1}]
+						}
+					}
+				}
+			]`,
+		},
 		{
 			name: "feature event has non-standard defaults for ratio and exclusion fields",
 			inputEventsJSON: `
@@ -106,13 +128,13 @@ func makeAllSummarizeEventsParams() []summarizeEventsParams {
 			name: "feature event includes the provided sampling ratio",
 			inputEventsJSON: `
 			[
-				{ "kind": "feature", "creationDate": 1000, "key": "flagkey", "user": {"key": "userkey"},
+				{ "kind": "feature", "creationDate": 1000, "key": "flagkey", "context": {"key": "userkey"},
 				"value": "b", "default": "c", "version": 11, "variation": 1, "trackEvents": true, "samplingRatio": 0 }
 			]`,
 			expectedEventsJSON: `
 			[
 				{"kind":"index","creationDate":1000,"context":{"key": "userkey"}},
-				{"kind":"feature","creationDate":1000,"key":"flagkey","version":11,"contextKeys":{"user":"userkey"},"variation":1,"value":"b","default":"c","samplingRatio":0},
+				{"kind":"feature","creationDate":1000,"key":"flagkey","version":11,"context":{"key":"userkey"},"variation":1,"value":"b","default":"c","samplingRatio":0},
 				{"kind":"summary","startDate":1000,"endDate":1000,"features":{"flagkey":{"default":"c","counters":[{"variation":1,"version":11,"value":"b","count":1}],"contextKinds":["user"]}}}
 			]`,
 		},
@@ -126,7 +148,7 @@ func makeAllSummarizeEventsParams() []summarizeEventsParams {
 			expectedEventsJSON: `
 			[
 				{"kind":"index","creationDate":1000,"context":{"key": "userkey"}},
-				{"kind":"feature","creationDate":1000,"key":"flagkey","version":11,"contextKeys":{"user":"userkey"},"variation":1,"value":"b","default":"c"}
+				{"kind":"feature","creationDate":1000,"key":"flagkey","version":11,"context":{"key":"userkey"},"variation":1,"value":"b","default":"c"}
 			]`,
 		},
 		{
diff --git a/internal/events/summarizing-relay_test.go b/internal/events/summarizing-relay_test.go
index fb110f74..3e2357dd 100644
--- a/internal/events/summarizing-relay_test.go
+++ b/internal/events/summarizing-relay_test.go
@@ -48,7 +48,10 @@ func TestSummarizeEvents(t *testing.T) {
 					_, _ = st.UpsertFlag(p.dataStore, ep.storedFlag)
 				}
 
-				req := st.BuildRequest("POST", "/", []byte(ep.inputEventsJSON), headersWithEventSchema(ep.schemaVersion))
+				headers := headersWithEventSchema(ep.schemaVersion)
+				headers.Set(EventUnsummarizedHeader, "true")
+
+				req := st.BuildRequest("POST", "/", []byte(ep.inputEventsJSON), headers)
 				p.dispatcher.GetHandler(basictypes.ServerSDK, ldevents.AnalyticsEventDataKind)(httptest.NewRecorder(), req)
 				p.dispatcher.flush()