From 406a8e343cbb13d89e4370afc5bb6d15f8cb86bf Mon Sep 17 00:00:00 2001
From: Ale Mercado <maria.mercado@slack-corp.com>
Date: Wed, 27 May 2026 12:01:09 -0600
Subject: [PATCH 1/2] feat(web): expose public ts property on ChatStream for
 fallback recovery

---
 slack_sdk/web/async_chat_stream.py      |  9 +++++++++
 slack_sdk/web/chat_stream.py            |  9 +++++++++
 tests/slack_sdk/web/test_chat_stream.py | 16 ++++++++++++++++
 3 files changed, 34 insertions(+)

diff --git a/slack_sdk/web/async_chat_stream.py b/slack_sdk/web/async_chat_stream.py
index a527c41e1..20e3fd98b 100644
--- a/slack_sdk/web/async_chat_stream.py
+++ b/slack_sdk/web/async_chat_stream.py
@@ -86,6 +86,15 @@ def __init__(
         self._stream_ts: Optional[str] = None
         self._buffer_size = buffer_size
 
+    @property
+    def ts(self) -> Optional[str]:
+        """The message timestamp of the stream.
+
+        Returns None until the first flush (when chat.startStream is called).
+        Can be used with chat.update as a fallback if the stream expires server-side.
+        """
+        return self._stream_ts
+
     async def append(
         self,
         *,
diff --git a/slack_sdk/web/chat_stream.py b/slack_sdk/web/chat_stream.py
index 7bd2daec9..9f97ac7cc 100644
--- a/slack_sdk/web/chat_stream.py
+++ b/slack_sdk/web/chat_stream.py
@@ -76,6 +76,15 @@ def __init__(
         self._stream_ts: Optional[str] = None
         self._buffer_size = buffer_size
 
+    @property
+    def ts(self) -> Optional[str]:
+        """The message timestamp of the stream.
+
+        Returns None until the first flush (when chat.startStream is called).
+        Can be used with chat.update as a fallback if the stream expires server-side.
+        """
+        return self._stream_ts
+
     def append(
         self,
         *,
diff --git a/tests/slack_sdk/web/test_chat_stream.py b/tests/slack_sdk/web/test_chat_stream.py
index 2db5dff88..841de9c38 100644
--- a/tests/slack_sdk/web/test_chat_stream.py
+++ b/tests/slack_sdk/web/test_chat_stream.py
@@ -262,6 +262,22 @@ def test_streams_with_authorship_args(self):
             self.assertEqual(start_request.get("icon_emoji"), "abacus")
             self.assertNotIn("icon_url", start_request)
 
+    def test_ts_property_is_none_before_flush_and_set_after(self):
+        streamer = self.client.chat_stream(
+            buffer_size=5,
+            channel="C0123456789",
+            thread_ts="123.000",
+            recipient_team_id="T0123456789",
+            recipient_user_id="U0123456789",
+        )
+        self.assertIsNone(streamer.ts)
+
+        streamer.append(markdown_text="hello!")
+        self.assertEqual(streamer.ts, "123.123")
+
+        streamer.stop()
+        self.assertEqual(streamer.ts, "123.123")
+
     def test_streams_errors_when_appending_to_an_unstarted_stream(self):
         streamer = self.client.chat_stream(
             channel="C0123456789",

From 6ddc8d348b24866b50d7508eeb914b6f31b24cac Mon Sep 17 00:00:00 2001
From: Ale Mercado <maria.mercado@slack-corp.com>
Date: Fri, 29 May 2026 14:15:18 -0600
Subject: [PATCH 2/2] add async tests

---
 .../web/test_async_chat_stream.py               | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/tests/slack_sdk_async/web/test_async_chat_stream.py b/tests/slack_sdk_async/web/test_async_chat_stream.py
index 2a4f5b931..5d5ccf344 100644
--- a/tests/slack_sdk_async/web/test_async_chat_stream.py
+++ b/tests/slack_sdk_async/web/test_async_chat_stream.py
@@ -244,6 +244,23 @@ async def test_streams_a_chunk_message(self):
                 '[{"text": "\\n", "type": "markdown_text"}, {"text": ":space_invader:", "type": "markdown_text"}]',
             )
 
+    @async_test
+    async def test_ts_property_is_none_before_flush_and_set_after(self):
+        streamer = await self.client.chat_stream(
+            buffer_size=5,
+            channel="C0123456789",
+            thread_ts="123.000",
+            recipient_team_id="T0123456789",
+            recipient_user_id="U0123456789",
+        )
+        self.assertIsNone(streamer.ts)
+
+        await streamer.append(markdown_text="hello!")
+        self.assertEqual(streamer.ts, "123.123")
+
+        await streamer.stop()
+        self.assertEqual(streamer.ts, "123.123")
+
     @async_test
     async def test_streams_errors_when_appending_to_an_unstarted_stream(self):
         streamer = await self.client.chat_stream(