There was never a campaign where the command dynamic in the Army of Northern Virginia was Longstreet the anvil and Jackson the hammer, despite it being popularized by Bob Krick the Elder.
In the Seven Days Campaigns, Longstreet and Jackson were usually slotted for offensive roles, with exception (Glendale, where Jackson and Huger were supposed to strike the Federal flanks, and Malvern Hill where Longstreet was in reserve). At the Second Manassas Campaign, the best description would be Jackson was the maneuver element and Longstreet the assaulting element. It was Jackson who held the main attention of Pope's army while Longstreet delivered the decisive blow.
At the Antietam Battle, both Jackson and Longstreet were defensive at the battle and maneuver elements in the campaign. And they were defensive at Fredericksburg as well. And at Chancellorsville, Longstreet was detached.
I think its a simplification when we try to categorize officers or units in such a manner. Lee, a sophisticated general, often needed different generals capable of doing different duties simultaneously. I don't think Lee approached a campaign with the attitude of "Longstreet is good at this and Jackson is good at that, so Longstreet's Corps will do this and Jackson's Corps will do that." His command approach and the strategic situation required flexibility.