Before: main 200dad3b39, Linux fs-31, web dev server, Chrome 1280x800.
UI steps: enable only worktreeOnDelete; add tiny git project; create thread in New worktree; ask Codex gpt-6.1-sol native spawn_agent to reply child done; wait for parent done; delete parent using Thread actions > Delete > Confirm; Settings > Storage > Delete now.
Observed cleanup UI: worktree t3-7d7d6c30 kept; Thread /root/child; Reason Has commits beyond the default branch.
{"id": "72981082-34a4-46fd-b7c5-a582558f9535", "title": "Test Subagent Completion", "lineage": {"parentThreadId": null, "relationshipToParent": null, "rootThreadId": "72981082-34a4-46fd-b7c5-a582558f9535"}, "branch": "t3/spawn-child-agent", "worktreePath": "/home/ubuntu/wt/issue-17812/.t3/worktrees/issue-17812-repro/t3-7d7d6c30", "deletedAt": "2026-10-22T23:32:35.297Z"}
worktree exists: True
git status --porcelain: 
{"id": "thread:provider:codex:native-thread:01a165f5-2492-7152-9ab7-f54404a1f461", "title": "/root/child", "lineage": {"parentThreadId": "72981082-34a4-46fd-b7c5-a582558f9535", "relationshipToParent": "subagent", "rootThreadId": "72981082-34a4-46fd-b7c5-a582558f9535"}, "branch": "t3/spawn-child-agent", "worktreePath": "/home/ubuntu/wt/issue-17812/.t3/worktrees/issue-17812-repro/t3-7d7d6c30", "deletedAt": null}
worktree exists: True
git status --porcelain: