fix: removed-trim-pipeline-buffer-to-prevent-event-loss

Author: Zaimwa9

flagsmith-core.ts

@@ -277,8 +277,8 @@ const Flagsmith = class {
 
         const environmentKey = this.evaluationContext.environment!.apiKey;
         this.isPipelineFlushing = true;
-        const eventsToSend = this.pipelineEvents;
-        this.pipelineEvents = [];
+        const eventsToSend = this.pipelineEvents.slice(0, this.evaluationAnalyticsMaxBuffer);
+        this.pipelineEvents = this.pipelineEvents.slice(this.evaluationAnalyticsMaxBuffer);
         this.pipelineRecordedKeys.clear();
 
         const batch: IPipelineEventBatch = {
@@ -302,7 +302,6 @@ const Flagsmith = class {
             this.log('Pipeline analytics: flush successful');
         } catch (err) {
             this.pipelineEvents = eventsToSend.concat(this.pipelineEvents);
-            this.trimPipelineBuffer();
             this.log('Pipeline analytics: flush failed, events re-queued', err);
         } finally {
             this.isPipelineFlushing = false;
@@ -1008,13 +1007,6 @@ const Flagsmith = class {
         this.pipelineRecordedKeys.clear();
     }
 
-    private trimPipelineBuffer() {
-        if (this.pipelineEvents.length > this.evaluationAnalyticsMaxBuffer) {
-            const excess = this.pipelineEvents.length - this.evaluationAnalyticsMaxBuffer;
-            this.pipelineEvents = this.pipelineEvents.slice(excess);
-        }
-    }
-
     // Pipeline event schema — must match the pipeline server's Event struct.
     // To update: 1) IPipelineEvent in types.d.ts  2) event object below  3) tests in test/analytics-pipeline.test.ts
     private recordPipelineEvent(key: string) {
@@ -1042,9 +1034,8 @@ const Flagsmith = class {
             },
         };
         this.pipelineEvents.push(event);
-        this.trimPipelineBuffer();
 
-        if (this.pipelineFlushInterval === 0) {
+        if (this.pipelineFlushInterval === 0 || this.pipelineEvents.length >= this.evaluationAnalyticsMaxBuffer) {
             this.flushPipelineAnalytics();
         }
     }

test/analytics-pipeline.test.ts

@@ -89,8 +89,8 @@ describe('Pipeline Analytics', () => {
         });
     });
 
-    test('should cap buffer at maxBuffer and skip events when skipAnalytics is used', async () => {
-        const { flagsmith, initConfig } = getFlagsmith({
+    test('should flush excess events when buffer exceeds maxBuffer and skip events when skipAnalytics is used', async () => {
+        const { flagsmith, initConfig, mockFetch } = getFlagsmith({
             evaluationAnalyticsConfig: {
                 analyticsServerUrl: pipelineUrl,
                 maxBuffer: 3,
@@ -110,12 +110,17 @@ describe('Pipeline Analytics', () => {
         flagsmith.getValue('number_value');
         flagsmith.getValue('off_value');
 
+        const calls = mockFetch.mock.calls.filter(([url]: [string, any]) => url.includes('v1/analytics/batch'));
+        expect(calls).toHaveLength(1);
+        const flushedBatch = JSON.parse(calls[0][1].body).events;
+        expect(flushedBatch).toHaveLength(3);
+        expect(flushedBatch[0].event_id).toBe('hero');
+        expect(flushedBatch[2].event_id).toBe('json_value');
+
+        // @ts-ignore — remaining events kept for next flush
+        expect(flagsmith.pipelineEvents).toHaveLength(2);
         // @ts-ignore
-        expect(flagsmith.pipelineEvents).toHaveLength(3);
-        // @ts-ignore
-        expect(flagsmith.pipelineEvents[0].event_id).toBe('json_value');
-        // @ts-ignore
-        expect(flagsmith.pipelineEvents[2].event_id).toBe('off_value');
+        expect(flagsmith.pipelineEvents[0].event_id).toBe('number_value');
     });
 
     test('should deduplicate repeated evaluations with same result per flush window', async () => {