From 099e9c747868933e5e7675916d50fc6c39635ebd Mon Sep 17 00:00:00 2001
From: Ryan Gaus <rsg1egoman@gmail.com>
Date: Fri, 17 Apr 2026 13:32:21 -0400
Subject: [PATCH 1/4] fix: avoid attaching a new Closing event listener for
 each waitForBufferStatusLow call

This can very quickly start to log lots of warnings.
---
 src/room/RTCEngine.ts | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/src/room/RTCEngine.ts b/src/room/RTCEngine.ts
index 4bf7cb1cd4..045f22f1e3 100644
--- a/src/room/RTCEngine.ts
+++ b/src/room/RTCEngine.ts
@@ -86,6 +86,7 @@ import type { TrackPublishOptions, VideoCodec } from './track/options';
 import { getTrackPublicationInfo } from './track/utils';
 import type { LoggerOptions } from './types';
 import {
+  Future,
   isCompressionStreamSupported,
   isVideoCodec,
   isVideoTrack,
@@ -249,6 +250,8 @@ export default class RTCEngine extends (EventEmitter as new () => TypedEventEmit
   /** used to indicate whether the browser is currently waiting to reconnect */
   private isWaitingForNetworkReconnect: boolean = false;
 
+  private bufferStatusLowClosingFuture = new Future<void, UnexpectedConnectionState>();
+
   constructor(private options: InternalRoomOptions) {
     super();
     this.log = getLogger(options.loggerName ?? LoggerNames.Engine);
@@ -282,6 +285,13 @@ export default class RTCEngine extends (EventEmitter as new () => TypedEventEmit
     this.client.onParticipantUpdate = (updates) =>
       this.emit(EngineEvent.ParticipantUpdate, updates);
     this.client.onJoined = (joinResponse) => this.emit(EngineEvent.Joined, joinResponse);
+
+    this.on(EngineEvent.Closing, () => {
+      this.bufferStatusLowClosingFuture.reject?.(new UnexpectedConnectionState('engine closed'));
+    });
+    // Swallow the rejection at the source so it doesn't surface as an unhandled promise rejection
+    // when no waitForBufferStatusLow callers are attached.
+    this.bufferStatusLowClosingFuture.promise.catch(() => {});
   }
 
   /** @internal */
@@ -1578,19 +1588,15 @@ export default class RTCEngine extends (EventEmitter as new () => TypedEventEmit
       if (this.isBufferStatusLow(kind)) {
         resolve();
       } else {
-        const onClosing = () => reject(new UnexpectedConnectionState('engine closed'));
-        this.once(EngineEvent.Closing, onClosing);
         const dc = this.dataChannelForKind(kind);
         if (!dc) {
           reject(new UnexpectedConnectionState(`DataChannel not found, kind: ${kind}`));
           return;
         }
+        this.bufferStatusLowClosingFuture.promise.catch((e) => reject(e));
         dc.addEventListener(
           'bufferedamountlow',
-          () => {
-            this.off(EngineEvent.Closing, onClosing);
-            resolve();
-          },
+          () => resolve(),
           {
             once: true,
           },

From ae278bb5b36087304ba72e4304408449c7851189 Mon Sep 17 00:00:00 2001
From: Ryan Gaus <rsg1egoman@gmail.com>
Date: Fri, 17 Apr 2026 13:40:47 -0400
Subject: [PATCH 2/4] fix: add missing changeset

---
 .changeset/modern-birds-lose.md | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 .changeset/modern-birds-lose.md

diff --git a/.changeset/modern-birds-lose.md b/.changeset/modern-birds-lose.md
new file mode 100644
index 0000000000..2f955bafb6
--- /dev/null
+++ b/.changeset/modern-birds-lose.md
@@ -0,0 +1,5 @@
+---
+'livekit-client': patch
+---
+
+Avoid attaching a new Closing event listener for each waitForBufferStatusLow call

From f89dca8c8c9e7b92939bb9a2482abf1653f7149a Mon Sep 17 00:00:00 2001
From: Ryan Gaus <rsg1egoman@gmail.com>
Date: Fri, 17 Apr 2026 13:41:13 -0400
Subject: [PATCH 3/4] fix: run npm run format

---
 src/room/RTCEngine.ts | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/src/room/RTCEngine.ts b/src/room/RTCEngine.ts
index 045f22f1e3..e07b3c7c42 100644
--- a/src/room/RTCEngine.ts
+++ b/src/room/RTCEngine.ts
@@ -1594,13 +1594,9 @@ export default class RTCEngine extends (EventEmitter as new () => TypedEventEmit
           return;
         }
         this.bufferStatusLowClosingFuture.promise.catch((e) => reject(e));
-        dc.addEventListener(
-          'bufferedamountlow',
-          () => resolve(),
-          {
-            once: true,
-          },
-        );
+        dc.addEventListener('bufferedamountlow', () => resolve(), {
+          once: true,
+        });
       }
     });
   }

From 1e97f7cb1dfd8e10e3eb24a4fbc40709662d1064 Mon Sep 17 00:00:00 2001
From: Ryan Gaus <rsg1egoman@gmail.com>
Date: Mon, 20 Apr 2026 12:48:51 -0400
Subject: [PATCH 4/4] fix: swap void -> never

---
 src/room/RTCEngine.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/room/RTCEngine.ts b/src/room/RTCEngine.ts
index e07b3c7c42..e95a77742c 100644
--- a/src/room/RTCEngine.ts
+++ b/src/room/RTCEngine.ts
@@ -250,7 +250,7 @@ export default class RTCEngine extends (EventEmitter as new () => TypedEventEmit
   /** used to indicate whether the browser is currently waiting to reconnect */
   private isWaitingForNetworkReconnect: boolean = false;
 
-  private bufferStatusLowClosingFuture = new Future<void, UnexpectedConnectionState>();
+  private bufferStatusLowClosingFuture = new Future<never, UnexpectedConnectionState>();
 
   constructor(private options: InternalRoomOptions) {
     super();