diff --git a/src/bin/cli.tsx b/src/bin/cli.tsx
index b93e7e7..507dfe4 100644
--- a/src/bin/cli.tsx
+++ b/src/bin/cli.tsx
@@ -15,9 +15,8 @@ const options = program.opts();
 const sampleMode = options.sample;
 
 async function loadSpans(): Promise<Array<Span>> {
-  if (!fs.existsSync('spans.jsonl')) return [];
   const spans: Array<Span> = [];
-  const file = await fs.promises.open('testSpans.jsonl', 'r');
+  const file = await fs.promises.open('span.jsonl', 'r');
   for await (const line of file.readLines()) {
     spans.push(JSON.parse(line));
   }
diff --git a/src/lib/Tracer.ts b/src/lib/Tracer.ts
index b434626..e4679a1 100644
--- a/src/lib/Tracer.ts
+++ b/src/lib/Tracer.ts
@@ -1,12 +1,13 @@
+import type { SpanEvent } from './types.js';
 import Span from './Span.js';
 
 class Tracer {
   protected activeSpans: Map<string, Span> = new Map();
-  protected queue: Array<Span> = [];
+  protected queue: Array<SpanEvent> = [];
   protected resolveWaitChunksP: (() => void) | undefined;
   protected ended: boolean = false;
 
-  protected queueSpan(span: Span) {
+  protected queueSpanEvent(span: SpanEvent) {
     this.queue.push(span);
     if (this.resolveWaitChunksP != null) this.resolveWaitChunksP();
   }
@@ -14,11 +15,10 @@ class Tracer {
   public startSpan(name: string, parentSpanId?: string): string {
     const span = new Span(name, parentSpanId);
     this.activeSpans.set(span.spanId, span);
-
     if (parentSpanId && this.activeSpans.has(parentSpanId)) {
       this.activeSpans.get(parentSpanId)!.children.push(span);
     }
-
+    this.queueSpanEvent({ type: 'start', span: span.toJSON() });
     return span.spanId;
   }
 
@@ -27,7 +27,7 @@ class Tracer {
     if (!span) return;
 
     span.close();
-    this.queueSpan(span);
+    this.queueSpanEvent({ type: 'stop', span: span.toJSON() });
     return span;
   }
 
@@ -56,7 +56,7 @@ class Tracer {
     this.ended = true;
   }
 
-  public async *streamEvents(): AsyncGenerator<Span, void, void> {
+  public async *streamEvents(): AsyncGenerator<SpanEvent, void, void> {
     while (true) {
       const value = this.queue.shift();
       if (value == null) {
diff --git a/src/lib/types.ts b/src/lib/types.ts
index 09811b1..d2ee4c0 100644
--- a/src/lib/types.ts
+++ b/src/lib/types.ts
@@ -8,4 +8,9 @@ type SpanJSON = {
   children: Array<SpanJSON>;
 };
 
-export type { SpanJSON };
+type SpanEvent = {
+  type: 'start' | 'stop';
+  span: SpanJSON;
+};
+
+export type { SpanJSON, SpanEvent };
diff --git a/tests/asciinemaTest.ts b/tests/asciinemaTest.ts
index 056d9e7..aafed31 100644
--- a/tests/asciinemaTest.ts
+++ b/tests/asciinemaTest.ts
@@ -159,7 +159,7 @@ setInterval(async () => {
   }
 
   step++;
-  process.stderr.write('generated data step');
+  process.stderr.write('generated data step\n');
 }, 500);
 
 await saveToFileP;