diff --git a/docs/superpowers/specs/2026-04-22-worktree-merge-design.md b/docs/superpowers/specs/2026-04-22-worktree-merge-design.md
index f70ae35..2a4c4a3 100644
--- a/docs/superpowers/specs/2026-04-22-worktree-merge-design.md
+++ b/docs/superpowers/specs/2026-04-22-worktree-merge-design.md
@@ -173,7 +173,7 @@ User clicks Merge (Details island or DiffModal)
 | `list.WorkingDir` null | `("blocked", [], "list has no working directory")` |
 | Merge conflict | `("conflict", [files], null)` — target auto-restored |
 | Unknown git failure | `HubException` with stderr |
-| Post-merge cleanup fails | Log a warning; merge already succeeded, state already `Merged`. Return `("merged", [], null)` with a note in `ErrorMessage`. |
+| Post-merge cleanup fails | Log a warning; merge already succeeded, state already `Merged`. Return `("merged", [], "cleanup: {reason}")` — `Status=="merged"` with a non-null `ErrorMessage` means the merge went through but the worktree couldn't be removed. UI surfaces this as a yellow note, not a failure. |
 
 ## Testing