ref(issue-ownership): switch issue assignment off OwnerActorField

[cvxluo]

Be more permissive when assigning issue owners. Two forms of this:

• stop using OwnerActorField
• for open membership, allow issue assignment to any user or team, as long as the assigner has project level access

We want to stop using OwnerActorField since issue assignment doesn't convey any permissions increase or access to the issue, it's primarily a label for searching. Since issue ownership has its own validation in validate_assignedTo, this won't have any increase in permissions. Note that alerts, etc. still use OwnerActorField.

We also want to allow basically all issue assignment with open membership on. There were some previous edge cases, like where you couldn't assign a team to a issue if the team didn't have access to the project, even with open membership on. These will now be allowed.

Small docs update that clarifies this: getsentry/sentry-docs#17441

More context: https://www.notion.so/sentry/permissive-ownership-assignments-3348b10e4b5d806e91b4cbf12af6a26c?source=copy_link

[github-actions]

Backend Test Failures

Failures on 441eef5 in this run:

tests/sentry/integrations/slack/webhooks/actions/test_status.py::StatusActionTest::test_assign_issue_where_team_not_in_project_through_unfurl — log

[gw0] linux -- Python 3.13.1 /home/runner/work/sentry/sentry/.venv/bin/python3
tests/sentry/integrations/slack/webhooks/actions/test_status.py:622: in test_assign_issue_where_team_not_in_project_through_unfurl
    assert resp.data["text"].endswith("Cannot assign to a team without access to the project")
E   AssertionError: assert False
E    +  where False = <built-in method endswith of str object at 0x7f880cdfe730>('Cannot assign to a team without access to the project')
E    +    where <built-in method endswith of str object at 0x7f880cdfe730> = '[caring-egret] IntegrationError: Identity not found.'.endswith

tests/sentry/issues/endpoints/test_group_details.py::GroupUpdateTest::test_assign_unavailable_team — log

[gw1] linux -- Python 3.13.1 /home/runner/work/sentry/sentry/.venv/bin/python3
tests/sentry/issues/endpoints/test_group_details.py:619: in test_assign_unavailable_team
    assert response.status_code == 400, response.content
E   AssertionError: b'{"id":"36","shareId":null,"shortId":"BAR-1","title":"Hello world","culprit":null,"permalink":"http://testserver/orga...d":false,"count":"1","userCount":0,"firstSeen":"2026-04-22T18:04:22.201370Z","lastSeen":"2026-04-22T18:04:22.201366Z"}'
E   assert 200 == 400
E    +  where 200 = <Response status_code=200, "application/json">.status_code

tests/sentry/integrations/slack/webhooks/actions/test_status.py::StatusActionTest::test_assign_issue_where_team_not_in_project — log

[gw1] linux -- Python 3.13.1 /home/runner/work/sentry/sentry/.venv/bin/python3
tests/sentry/integrations/slack/webhooks/actions/test_status.py:608: in test_assign_issue_where_team_not_in_project
    assert resp.data["text"].endswith("Cannot assign to a team without access to the project")
E   AssertionError: assert False
E    +  where False = <built-in method endswith of str object at 0x7fe26d889170>('Cannot assign to a team without access to the project')
E    +    where <built-in method endswith of str object at 0x7fe26d889170> = '[suitable-sponge] IntegrationError: Identity not found.'.endswith

[cvxluo]

these are docs-only edits to clarify this new exception

[cursor]

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

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[shashjar]

nice

[geoffg-sentry]

Looking solid Charlie, thanks!