@@ -426,6 +426,8 @@ class BroadcastImpl {
   }
 
   #tryTrimBuffer() {
+    // Retain buffered data for consumers that attach while none are active.
+    if (this.#consumers.size === 0) return;
     if (this.#cachedMinCursorConsumers === 0) {
       this.#recomputeMinCursor();
     }
 
@@ -350,6 +350,18 @@ async function testLateJoinerSeesBufferedData() {
   assert.strictEqual(result, 'before-join');
 }
 
+async function testLateJoinerAfterDetachSeesBufferedData() {
+  const { writer, broadcast: bc } = broadcast({ budget: 16384 });
+  const first = bc.push()[Symbol.asyncIterator]();
+
+  writer.writeSync('before-detach');
+  await first.return();
+
+  const second = bc.push();
+  writer.endSync();
+  assert.strictEqual(await text(second), 'before-detach');
+}
+
 async function testOverlappingNextKeepsEarlierRead() {
   const { writer, broadcast: bc } = broadcast();
   const it = bc.push()[Symbol.asyncIterator]();
@@ -403,5 +415,6 @@ Promise.all([
   testFailDetachesConsumers(),
   testWriterFailIdempotent(),
   testLateJoinerSeesBufferedData(),
+  testLateJoinerAfterDetachSeesBufferedData(),
   testOverlappingNextKeepsEarlierRead(),
 ]).then(common.mustCall());
Original file line number	Diff line number	Diff line change
`@@ -426,6 +426,8 @@ class BroadcastImpl {`
`426`	`426`	`}`
`427`	`427`
`428`	`428`	`#tryTrimBuffer() {`
	`429`	`+ // Retain buffered data for consumers that attach while none are active.`
	`430`	`+ if (this.#consumers.size === 0) return;`
`429`	`431`	`if (this.#cachedMinCursorConsumers === 0) {`
`430`	`432`	`this.#recomputeMinCursor();`
`431`	`433`	`}`