YES. Lifetime appointment. Designed to keep them free from influence.
At the risk of being nitpicky, Article III, Section 1 doesn't specifically state "lifetime appointment" or anything approaching that.
The judicial Power of the United States, shall be vested in one supreme Court, and in such inferior Courts as the Congress may from time to time ordain and establish. The Judges, both of the supreme and inferior Courts, shall hold their Offices during good Behaviour, and shall, at stated Times, receive for their Services, a Compensation, which shall not be diminished during their Continuance in Office.
It's been interpreted that way, as you point out, but it's a stretch to say that lifetime appointments are "codified."
It's absolutely true that this interpretation for "lifetime" appointment or until resignation or impeachment is intended to keep those judges impartial, but I ask -- howzat workin' out?
We all know that all 9 of the justices lean one way or another. Kennedy was the so-called "swing" voter, and Thomas is most definitely in the conservative camp as Sotomayor is in the "liberal" camp. Could argue that Roberts is a swing voter, but based on his own voting record especially regarding Obamacare, I put him squarely in the "liberal" camp.
https://constitution.congress.gov/constitution/article-3/