fix: stop polling activity logs after an auth error

[mwbrooks]

Changelog

Fixed an issue where slack activity --tail and slack run kept requesting activity logs every few seconds after the login token became invalid. The command now exits with the auth error.

Summary

This pull request stops activity log polling when the activity API returns an auth error.

• While tailing, apps.activities.list errors were logged at debug level and retried on every tick (3 seconds by default) until the idle timeout. For slack run, the idle timeout is 24 hours.
• invalid_auth, not_authed, token_expired, and token_revoked now return the error and stop polling, because every later request with the same token would fail too.
• Other errors keep the current behavior of retrying on the next tick.

This is a follow-up to #679, which stops retrying token rotation with an invalid refresh token. The two changes are independent and can merge in either order.

Preview

$ slack activity --tail
✨ user of Example Workspace
☁️  2026-09-28 17:36:22 [info] Application Created by user 'U0123456789' on team 'E0123456789'
Check ~/.slack/logs/slack-debug-20260929.log for error logs
The following error was returned by the apps.activities.list Slack API method

🚫 Your token has already been revoked (token_revoked)

💡 Suggestion
   Use the command `slack login` to authenticate again

Testing

1. Run slack activity --tail for an app.
2. In another terminal, revoke the token used by the CLI, e.g. slack logout for that workspace.
3. Confirm slack activity --tail exits with an auth error on the next poll instead of continuing to poll.
4. Repeat with slack run and confirm it exits with the auth error.

Notes

• In slack run, an auth error from activity polling now ends the run session, which is consistent with how other errors from the run goroutines are handled.

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.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.23%. Comparing base (7076706) to head (073e9b0).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #680      +/-   ##
==========================================
+ Coverage   78.22%   78.23%   +0.01%     
==========================================
  Files         239      239              
  Lines       18144    18149       +5     
==========================================
+ Hits        14193    14199       +6     
+ Misses       3951     3950       -1     

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[srtaalej]

thank you for quick followups!

[mwbrooks]

Thanks a lot for the second pair of eyes @srtaalej! 🙇🏻