From 41a7e14af514a6b1a3bf8e9ee21a205e2fec6aaa Mon Sep 17 00:00:00 2001
From: Ryan Gaus <rsg1egoman@gmail.com>
Date: Wed, 4 Feb 2026 18:18:47 -0500
Subject: [PATCH 1/2] feat: add attachedStreamIds as text stream metadata

This allows downstream libraries to determine which "attachments" were
sent in a data stream so the previous legacy chat message files
interface can be satisfied.
---
 src/room/data-stream/incoming/IncomingDataStreamManager.ts | 1 +
 src/room/data-stream/outgoing/OutgoingDataStreamManager.ts | 3 ++-
 src/room/types.ts                                          | 4 +++-
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/room/data-stream/incoming/IncomingDataStreamManager.ts b/src/room/data-stream/incoming/IncomingDataStreamManager.ts
index 4cf7f34202..e739844e7b 100644
--- a/src/room/data-stream/incoming/IncomingDataStreamManager.ts
+++ b/src/room/data-stream/incoming/IncomingDataStreamManager.ts
@@ -191,6 +191,7 @@ export default class IncomingDataStreamManager {
         timestamp: Number(streamHeader.timestamp),
         attributes: streamHeader.attributes,
         encryptionType,
+        attachedStreamIds: streamHeader.contentHeader.value.attachedStreamIds,
       };
 
       const stream = new ReadableStream<DataStream_Chunk>({
diff --git a/src/room/data-stream/outgoing/OutgoingDataStreamManager.ts b/src/room/data-stream/outgoing/OutgoingDataStreamManager.ts
index 02df785aee..b5eec14e5b 100644
--- a/src/room/data-stream/outgoing/OutgoingDataStreamManager.ts
+++ b/src/room/data-stream/outgoing/OutgoingDataStreamManager.ts
@@ -107,6 +107,7 @@ export default class OutgoingDataStreamManager {
       encryptionType: this.engine.e2eeManager?.isDataChannelEncryptionEnabled
         ? Encryption_Type.GCM
         : Encryption_Type.NONE,
+      attachedStreamIds: options?.attachedStreamIds,
     };
     const header = new DataStream_Header({
       streamId,
@@ -119,7 +120,7 @@ export default class OutgoingDataStreamManager {
         case: 'textHeader',
         value: new DataStream_TextHeader({
           version: options?.version,
-          attachedStreamIds: options?.attachedStreamIds,
+          attachedStreamIds: info.attachedStreamIds,
           replyToStreamId: options?.replyToStreamId,
           operationType:
             options?.type === 'update'
diff --git a/src/room/types.ts b/src/room/types.ts
index 9536eeaeda..fdfb36d4ec 100644
--- a/src/room/types.ts
+++ b/src/room/types.ts
@@ -142,4 +142,6 @@ export interface ByteStreamInfo extends BaseStreamInfo {
   name: string;
 }
 
-export interface TextStreamInfo extends BaseStreamInfo {}
+export interface TextStreamInfo extends BaseStreamInfo {
+  attachedStreamIds?: Array<string>;
+}

From ca1f59c7e9838c16ce2a4c1ce2b20e1359054de3 Mon Sep 17 00:00:00 2001
From: Ryan Gaus <rsg1egoman@gmail.com>
Date: Wed, 4 Feb 2026 18:34:25 -0500
Subject: [PATCH 2/2] fix: add missing changeset

---
 .changeset/spotty-tigers-sort.md | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 .changeset/spotty-tigers-sort.md

diff --git a/.changeset/spotty-tigers-sort.md b/.changeset/spotty-tigers-sort.md
new file mode 100644
index 0000000000..1efe600819
--- /dev/null
+++ b/.changeset/spotty-tigers-sort.md
@@ -0,0 +1,5 @@
+---
+'livekit-client': patch
+---
+
+Add attachedStreamIds as text stream metadata