diff --git a/livekit-rtc/livekit/rtc/_utils.py b/livekit-rtc/livekit/rtc/_utils.py
index c7fbc092..fd7e452f 100644
--- a/livekit-rtc/livekit/rtc/_utils.py
+++ b/livekit-rtc/livekit/rtc/_utils.py
@@ -17,7 +17,7 @@
 from collections import deque
 import ctypes
 import random
-from typing import Callable, Generic, List, TypeVar
+from typing import Callable, Generator, Generic, List, TypeVar
 
 logger = logging.getLogger("livekit")
 
@@ -133,12 +133,13 @@ def generate_random_base62(length=12):
 
 
 # adapted from https://stackoverflow.com/a/6043797
-def split_utf8(s: str, n: int):
+def split_utf8(s: str, n: int) -> Generator[bytes, None, None]:
     """Split UTF-8 s into chunks of maximum length n."""
-    while len(s) > n:
+    encoded = s.encode()
+    while len(encoded) > n:
         k = n
-        while (ord(s[k]) & 0xC0) == 0x80:
+        while (encoded[k] & 0xC0) == 0x80:
             k -= 1
-        yield s[:k]
-        s = s[k:]
-    yield s
+        yield encoded[:k]
+        encoded = encoded[k:]
+    yield encoded
diff --git a/livekit-rtc/livekit/rtc/data_stream.py b/livekit-rtc/livekit/rtc/data_stream.py
index 770a19e1..c7a22bf5 100644
--- a/livekit-rtc/livekit/rtc/data_stream.py
+++ b/livekit-rtc/livekit/rtc/data_stream.py
@@ -27,10 +27,10 @@
 from ._utils import split_utf8
 from typing import TYPE_CHECKING
 
+
 if TYPE_CHECKING:
     from .participant import LocalParticipant
 
-
 STREAM_CHUNK_SIZE = 15_000
 
 
@@ -65,7 +65,6 @@ def __init__(
             attachments=list(header.text_header.attached_stream_ids),
         )
         self._queue: asyncio.Queue[proto_DataStream.Chunk | None] = asyncio.Queue()
-        self._chunks: Dict[int, proto_DataStream.Chunk] = {}
 
     async def _on_chunk_update(self, chunk: proto_DataStream.Chunk):
         await self._queue.put(chunk)
@@ -146,6 +145,7 @@ def __init__(
         total_size: int | None = None,
         mime_type: str = "",
         destination_identities: Optional[List[str]] = None,
+        sender_identity: str | None = None,
     ):
         self._local_participant = local_participant
         if stream_id is None:
@@ -161,6 +161,7 @@ def __init__(
         )
         self._next_chunk_index: int = 0
         self._destination_identities = destination_identities
+        self._sender_identity = sender_identity or self._local_participant.identity
 
     async def _send_header(self):
         req = proto_ffi.FfiRequest(
@@ -168,7 +169,7 @@ async def _send_header(self):
                 header=self._header,
                 local_participant_handle=self._local_participant._ffi_handle.handle,
                 destination_identities=self._destination_identities,
-                sender_identity=self._local_participant.identity,
+                sender_identity=self._sender_identity,
             )
         )
 
@@ -230,10 +231,12 @@ async def _send_trailer(self, trailer: proto_DataStream.Trailer):
         if cb.send_stream_chunk.error:
             raise ConnectionError(cb.send_stream_trailer.error)
 
-    async def aclose(self):
+    async def aclose(
+        self, *, reason: str = "", attributes: Optional[Dict[str, str]] = None
+    ):
         await self._send_trailer(
             trailer=proto_DataStream.Trailer(
-                stream_id=self._header.stream_id, reason=""
+                stream_id=self._header.stream_id, reason=reason, attributes=attributes
             )
         )
 
@@ -249,6 +252,7 @@ def __init__(
         total_size: int | None = None,
         reply_to_id: str | None = None,
         destination_identities: Optional[List[str]] = None,
+        sender_identity: str | None = None,
     ) -> None:
         super().__init__(
             local_participant,
@@ -258,6 +262,7 @@ def __init__(
             total_size,
             mime_type="text/plain",
             destination_identities=destination_identities,
+            sender_identity=sender_identity,
         )
         self._header.text_header.operation_type = proto_DataStream.OperationType.CREATE
         if reply_to_id:
@@ -276,7 +281,7 @@ def __init__(
     async def write(self, text: str):
         async with self._write_lock:
             for chunk in split_utf8(text, STREAM_CHUNK_SIZE):
-                content = chunk.encode()
+                content = chunk
                 chunk_index = self._next_chunk_index
                 self._next_chunk_index += 1
                 chunk_msg = proto_DataStream.Chunk(
diff --git a/livekit-rtc/livekit/rtc/participant.py b/livekit-rtc/livekit/rtc/participant.py
index a520dd4d..e22f6648 100644
--- a/livekit-rtc/livekit/rtc/participant.py
+++ b/livekit-rtc/livekit/rtc/participant.py
@@ -585,8 +585,10 @@ async def stream_text(
         destination_identities: Optional[List[str]] = None,
         topic: str = "",
         attributes: Optional[Dict[str, str]] = None,
+        stream_id: str | None = None,
         reply_to_id: str | None = None,
         total_size: int | None = None,
+        sender_identity: str | None = None,
     ) -> TextStreamWriter:
         """
         Returns a TextStreamWriter that allows to write individual chunks of text to a text stream.
@@ -599,6 +601,8 @@ async def stream_text(
             reply_to_id=reply_to_id,
             destination_identities=destination_identities,
             total_size=total_size,
+            stream_id=stream_id,
+            sender_identity=sender_identity,
         )
 
         await writer._send_header()