feat: add authorship arguments to assistant threads and chat stream

[zimeg]

Summary

This pull request adds authorship arguments (icon_emoji, icon_url, username) to the assistant.threads.setStatus and chat.startStream Web API methods.

Mirrors slackapi/node-slack-sdk#2455 for the Python SDK.

Testing

Try the following snippet against an assistant thread:

importtimeclient.assistant_threads_setStatus(
channel_id="C018QLSQ38A",
thread_ts="1765934795.222209",
status="dancing...",
username="Charlie Brown",
icon_emoji="maple_leaf",
)
time.sleep(4)
response=client.chat_startStream(
channel="C018QLSQ38A",
thread_ts="1765934795.222209",
recipient_team_id="T07L2FPUY",
recipient_user_id="U0187GKV2US",
username="Charlie Brown",
icon_emoji="maple_leaf",
)
time.sleep(2)
client.chat_appendStream(
channel="C018QLSQ38A",
ts=response["ts"],
markdown_text="Dancing with snoopy dog.",
)
time.sleep(2)
client.chat_stopStream(
channel="C018QLSQ38A",
ts=response["ts"],
)

streamer=app.client.chat_stream(
channel="C07U19RTY90",
thread_ts="1777925328.173729",
recipient_user_id="U06MCF88LQY",
recipient_team_id="T06M2FAFCF3",
username="Charlie Brown",
icon_emoji="maple_leaf",
buffer_size=0,
)
streamer.append(markdown_text="Dancing with snoopy dog!")
time.sleep(2)
streamer.append(markdown_text=" Fun!")
streamer.stop()

Category

• slack_sdk.web.WebClient (sync/async) (Web API client)
• tests/integration_tests (Automated tests for this library)

Requirements

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.
• I've run python3 -m venv .venv && source .venv/bin/activate && ./scripts/run_validation.sh after making the changes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.00%. Comparing base (726538c) to head (c623822).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@ Coverage Diff @@## main #1862 +/- ##
==========================================
- Coverage 84.00% 84.00% -0.01% 
==========================================
Files 117 117 Lines 13257 13257 ==========================================
- Hits 11137 11136 -1 - Misses 2120 2121 +1 

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[srtaalej]

Looks great and working well for me ⭐ ⭐ ⭐

[zimeg]

@srtaalej Thanks so much for reviewing! I landed c623822 after reading the linked issue again to find that the included chat_stream helper requires these same arguments be defined for editor hints 🔍 ✨

The description has updated test steps if that's curious but I will plan to merge this soon otherwise 🚢