feat(ecosystem): Implement cross-system issue synchronization

[akshayutture-augment]

Test 7

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Replicated from ai-code-review-evaluation/sentry-cursor#7

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Note

Introduces AssignmentSource and threads it through assignee/status sync to prevent cross-integration assignment sync loops.

• Integrations
  • Add AssignmentSource (src/sentry/integrations/services/assignment_source.py) with from_integration, to_dict, from_dict for tracking assignment origin.
  • Extend IssueBasicIntegration.should_sync(...) and IssueSyncIntegration.should_sync(...) to accept sync_source and short-circuit when source integration matches, preventing sync cycles.
  • Extend IssueSyncIntegration.sync_status_outbound(...) to accept assignment_source.
• Tasks
  • Update sync_assignee_outbound task to accept assignment_source_dict, parse to AssignmentSource, pass to should_sync and sync_assignee_outbound.
• Utils
  • In sync_group_assignee_inbound, pass AssignmentSource.from_integration(...) to GroupAssignee.objects.assign/deassign.
  • In sync_group_assignee_outbound, forward assignment_source via assignment_source_dict to the task.
• Models
  • Update GroupAssigneeManager.assign/deassign to accept assignment_source and propagate to sync_group_assignee_outbound.
• Tests
  • Add tests for AssignmentSource serialization/parsing.
  • Update/extend GroupAssignee tests to verify outbound sync receives assignment_source and that matching-source integrations do not trigger outbound sync.

^{Written by Cursor Bugbot for commit f9919d7. Configure here.}

[akshayutture-augment]

cursor review

[cursor]

Bug: Default Timestamps: One for All

The queued field uses timezone.now() as a default value, which is evaluated once at class definition time rather than at instance creation time. This means all AssignmentSource instances will share the same timestamp instead of getting unique timestamps when created. Use field(default_factory=timezone.now) instead to generate a fresh timestamp for each instance.