slack-adapter shouldn't pick the username as a fullname

[sundaycrafts]

Bug Description

Slack adapter takes username as a fullname, but it's not intended to be public or full name as Slack UI says:

Usernames are not part of your profile, and are only required by Slack for technical reasons. Your username is mostly invisible to others, but you can change it if you want to.
Usernames must be all lowercase. They cannot be longer than 21 characters and can only contain letters, numbers, periods, hyphens, and underscores.
see https://<your_workspace>.slack.com/account/settings?updated_username=1#username

user.name is way better as a full name.

chat/packages/adapter-slack/src/index.ts

Line 1073 in af8c958

userName: payload.user.username || payload.user.name || "unknown",

Steps to Reproduce

1. Integrate Slack adapter
2. Send action block as a message
3. Retrieve "full name" from event.user.fullName

Expected Behavior

1. Integrate Slack adapter
2. Send action block as a message
3. Retrieve "full name" from event.user.fullName
4. It's something other than "username", such as "name"

Actual Behavior

1. Integrate Slack adapter
2. Send action block as a message
3. Retrieve "full name" from event.user.fullName
4. It's "username"

Code Sample

Chat SDK Version

4.20.2

Node.js Version

No response

Platform Adapter

Slack

Operating System

macOS

Additional Context

No response

[bensabic]

Thanks for reporting this. You're right that payload.user.name in Slack's action/modal payloads is the technical username (lowercase, invisible to most users), not the user's real name.

Unfortunately, Slack's interaction payloads (block_actions, view_submission, view_closed) only include user.id, user.name, and user.username — none of which are the display name or real name. Getting the real name requires an extra users.info API call.

The problem with adding that lookup in the action handler path is that Slack's trigger_id (needed for opening modals via event.openModal()) expires in ~3 seconds. An uncached users.info API call adds enough latency that it could cause modal opens to fail. Since action handlers are the primary path for opening modals, we can't safely add that latency.

For message events, we already do the lookup (via lookupUser()) because those don't have the same tight timing constraint — and the result gets cached so subsequent lookups are fast.

If you need the real name in an action handler, you can call the Slack API directly using the user ID from event.user.userId:

bot.onAction("my-action", async (event) => {
  const result = await slackClient.users.info({ user: event.user.userId });
  const realName = result.user?.real_name || result.user?.profile?.real_name;
  // ...
});

[sundaycrafts]

Thank you for your helpful information! That's reasonable design.