feat(web): expose public ts property on ChatStream

[srtaalej]

Summary

• Adds a public read-only ts property to ChatStream and AsyncChatStream, enabling users to call chat.update as a fallback when the server closes a stream due to undocumented timeouts.

Resolves#1859

Background

When Slack's server-side timeout kills a stream, both chat.appendStream and chat.stopStream return message_not_in_streaming_state. The message still exists but is stuck as a broken pill in the UI. The only recovery path is chat.update(ts=...), but ts was previously a private attribute (_stream_ts).

Changes

• slack_sdk/web/chat_stream.py: Added ts property (read-only, returns Optional[str])
• slack_sdk/web/async_chat_stream.py: Same (auto-generated via codegen)
• tests/slack_sdk/web/test_chat_stream.py: Added test verifying ts is None before flush and set after

code snippet

fromslack_sdkimportWebClientfromslack_sdk.errorsimportSlackApiErrorclient=WebClient(token=...)
defsend_streaming(channel, thread_ts, team_id, user_id, content_iter):
stream=client.chat_stream(
channel=channel,
thread_ts=thread_ts,
recipient_team_id=team_id,
recipient_user_id=user_id,
)
full_text=""stream_alive=Trueforchunkincontent_iter:
full_text+=chunkifstream_alive:
try:
stream.append(markdown_text=chunk)
exceptSlackApiErrorase:
ife.response["error"] =="message_not_in_streaming_state":
stream_alive=Falseelse:
raiseifnotstream_alive:
client.chat_update(channel=channel, ts=stream.ts, text=full_text)
ifstream_alive:
stream.stop()
else:
client.chat_update(channel=channel, ts=stream.ts, text=full_text)

Test plan

• Existing ChatStream tests pass
• New test verifies ts is None before first flush and set after
• CI passes

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.13%. Comparing base (e513558) to head (edc4598).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@ Coverage Diff @@## main #1880 +/- ##
=======================================
Coverage 84.12% 84.13% =======================================
Files 117 117 Lines 13340 13346 +6 =======================================
+ Hits 11222 11228 +6 
Misses 2118 2118 

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[WilliamBergamin]

Awesome work 💯 this look good

Could we mirror the unit test to cover the async implementation, once added I think we are good to merge 🙏

[WilliamBergamin]

🚀