GetThreadContext returns None in user_message handler

[jczhong84]

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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[srtaalej]

hi @jczhong84 thank you so much for reporting this! we've confirmed the bug and are working on a fix! 💟

[jczhong84]

Hi @srtaalej thanks for the quick fix! I've another question around this context change. When it clicks into a thread of a channel, it will also trigger thread_context_changed event, although the channel is not changed. So I think either

1. As the current context is about the channel id the user is viewing, can it only trigger the thread_context_changed when the channel changes?
2. or can we add the thread id into the context as well as the channel id? actually this will be really helpful for the ai assistant, as it will know the exact thread context user is viewing. And we're thinking if there is any workaround to do this.