[alexsohn1126]

Threads the notification platform saves now remember which integration sent them, in a new nullable integration_id column. Nothing reads it yet, so nothing changes for people in Slack.

A thread row only has the channel, so anything that wants to post back into a thread later couldn't tell which Slack workspace to use. The platform now takes the integration from the target when it creates a thread. Existing threads keep it empty. There's also a small helper to list the threads for an object, using the object columns #127289 started filling in.

The column is added during deploy, before the new code runs. #128771 uses both to send Seer investigation conclusions to every metric alert thread. Orgs with metric alert threading turned off don't save threads, so they only get the conclusion in the thread where someone clicked.

refs CW-2217

[linear-code]

CW-2217

[hobzcalvin]

I think there's precedent elsewhere to use a HybridCloudForeignKey which will handle the delete case for you:

integration_id = HybridCloudForeignKey("sentry.Integration", null=True, on_delete="SET_NULL")

[alexsohn1126]

done in 54bad49

[github-actions]

This PR has a migration; here is the generated SQL for src/sentry/notifications/migrations/0017_add_notificationthread_integration_id.py

for 0017_add_notificationthread_integration_id in notifications

--
-- Add field integration_id to notificationthread
--
ALTER TABLE "notifications_notificationthread" ADD COLUMN "integration_id" bigint NULL;
CREATE INDEX CONCURRENTLY "notifications_notificationthread_integration_id_a4a80f02" ON "notifications_notificationthread" ("integration_id");