Reproducible in:

slack_bolt==1.27.0
slack_sdk==3.40.1

The slack_bolt version

slack_bolt==1.27.0

Python runtime version

Python 3.12

OS info

Linux

Steps to reproduce:

1. Create an Assistant with either the default store or a custom AssistantThreadContextStore
2. Save thread context in thread_started using save_thread_context()
3. Call get_thread_context() in user_message handler

from slack_bolt import App
from slack_bolt import Assistant, Say

assistant = Assistant()  # default store or custom — same result

@assistant.thread_started
def handle_thread_started(say, save_thread_context, payload):
    thread_context = payload["assistant_thread"]["context"]
    save_thread_context(thread_context)  # ✅ works, store.save() is called
    say("Hi!")

@assistant.thread_context_changed
def handle_context_changed(save_thread_context, payload):
    new_context = payload["assistant_thread"]["context"]
    save_thread_context(new_context)  # ✅ works

@assistant.user_message
def handle_user_message(say, get_thread_context):
    ctx = get_thread_context()  # ❌ always None, store.find() never called
    print(ctx)

app = App(token="xoxb-...", signing_secret="...")
app.use(assistant)
app.start(port=3000)

Expected result:

get_thread_context() should call store.find() and return the previously saved context (e.g., {"channel_id": "C0ADEEWTZPB", "team_id": "TU8CUBAPP", ...}).

Actual result:

get_thread_context() always returns None. The store's find() method is never invoked.

Root cause

In GetThreadContext.call(), the code checks if "assistant_thread" in self.payload before checking for channel/thread_ts:

if "assistant_thread" in self.payload:
    context = self.payload["assistant_thread"].get("context", {})
    if context.get("channel_id"):
        self._thread_context = AssistantThreadContext(context)
    self.thread_context_loaded = True

elif self.payload.get("channel") and self.payload.get("thread_ts"):
    self._thread_context = self.thread_context_store.find(
        channel_id=self.payload["channel"],
        thread_ts=self.payload["thread_ts"],
    )

In assistant_thread_started events, payload["assistant_thread"] contains a full context dict — this works fine.

However, in user_message events, payload["assistant_thread"] only contains an action_token:

{
  "assistant_thread": {
    "action_token": "10647138185092.960436384805.afce3599..."
  }
}

Because the key "assistant_thread" exists, the if branch is entered. There's no context inside, so _thread_context stays None. Then thread_context_loaded is set to True, and the elif branch that calls store.find() is never reached.

Requirements

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