* fix(conversations): enforce NOT NULL + FK on contact_id
Conversations had contact_id nullable with no FK to contacts. Combined
with dependent: :destroy_async on Contact#conversations, deleting a
contact could leave conversations pointing to a missing contact,
breaking the conversations#index API with
"undefined method 'additional_attributes' for nil" from the contact
partial.
Changes:
- Migration cleans up existing orphans, sets contact_id NOT NULL and
adds a FK with ON DELETE CASCADE so the invariant is enforced at the
DB level (complements the existing Rails presence validation).
- ContactMergeAction uses update_all for conversations/messages/notes/
contact_inboxes so a failing callback cannot silently leave records
pointing to the mergee contact before it is destroyed.
- Drop the now-redundant orphan filter in Conversations::ResolutionJob
and its spec; the invariant is enforced at the schema level.
* fix: address review feedback
- Drop the ON DELETE CASCADE FK on conversations.contact_id. Several
conversation-owned tables (messages, mentions, conversation_participants,
reporting_events, csat_survey_responses, calls, applied_slas, sla_events,
and polymorphic notifications) still have plain conversation_id references
without FK cascades. The DB-level cascade would skip Conversation's
dependent: cleanup and replace the NULL-contact bug with orphan children,
and would also conflict with the existing non-cascade FKs on
scheduled_messages/recurring_scheduled_messages. Keep the invariant at the
Rails layer (NOT NULL + presence validation + dependent: :destroy_async).
- Clean up orphan conversations in the migration via Rails destroy so
dependent associations are propagated correctly, instead of a raw
DELETE FROM conversations that would orphan all child rows.
- Revert ContactMergeAction.merge_* methods back to per-record update! so
Conversation#after_update_commit still fires (notify_status_change /
CONVERSATION_CONTACT_CHANGED) for contact_id changes. The bang form
still removes the silent-failure risk of the original .update call.