In a motion for habeas corpus, what is the test for "no satisfactory explanation" for the actions of counsel on appeal?

Where the record on appeal "sheds no light" on why counsel acted or failed to act in the manner challenged, we will affirm the judgment unless there could be "no satisfactory explanation" for counsel's actions. (People v. Ledesma (2006) 39 Cal.4th 641, 746.) Where the record does not illuminate the basis for a challenged act or omission, a defendant's claim of ineffective assistance of counsel is more appropriately made in a petition for habeas corpus where there is an opportunity in an evidentiary hearing to have trial counsel fully describe his or her reasons for acting or failing to act in the manner challenged. (Ibid.)