feat(slack): Add Slack Agent DM and assistant thread support for Seer Explorer

[leeandher]

this allows DMs to the bot trigger Seer and gives a richer experience for starting conversations by suggesting prompts. to support this locally, you need to do a few things

• Enable Agent + AI App for Slack App
• Add the assistant:write OAuth scope
• Add event subscriptions for assistant_thread_started

Refs ISWF-2388

[linear-code]

ISWF-2388 Explore Slack DMs + Agent interface for Seer Explorer

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[cursor]

Identity check bypassed for assistant_thread_started events

Low Severity

The org membership check in _resolve_seer_organization relies on slack_request.get_identity_user(), which resolves the user via slack_request.user_id. For assistant_thread_started events, the user ID lives at event.assistant_thread.user_id, but SlackEventRequest.user_id reads from event.user, returning "". This means identity_user is always None for these events, causing the if identity_user and not organization.has_access(identity_user) check to be silently skipped. The first org with Seer access is selected without verifying user membership — the exact security gap the PR discussion identified and intended to close. Impact is limited today since the handler only sends generic prompts, but it undermines the access control model.

Additional Locations (1)

• src/sentry/integrations/slack/webhooks/event.py#L494-L497

 

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