Casey Affleck Files Mysterious Divorce Docs, But Settlement Reached

Casey Affleck and his estranged wife, Summer Phoenix, will NOT have a nasty, drawn-out divorce -- despite a weird filing -- we've learned it's all settled already.

Casey filed docs Monday responding to Summer's divorce petition ... filed that same day. Much of his reads just like hers -- irreconcilable differences, 2 kids and same date of separation. However, in his docs, Casey says he wants the court to block Summer from getting the spousal support she had requested in her docs.

On paper, seems like a dogfight is brewing ... but sources connected to the ex-couple tell us they've already hammered out a settlement, just 4 days after she filed. We're told Casey is paying spousal support under the agreement.

It's unclear why he checked the box to block spousal support only to cave a few days later -- but what's done is done.