What materials are needed to repair real stucco hairline cracks?

Brushable caulk is the thing to use for hairline cracks. It was used on our condo in Florida. Old stucco on concrete block had no large cracks, only hairline. Pro painter used it with excellent results. Later, where there were chinks out of corners of blocks, such as where it was hit with mower, etc., I modeled in latex stucco repair. I also used the stucco repair like mortar with concrete pavers to fill a niche that had held an old fire extinguisher. Let it cure well, apply stucco repair for surface, paint, and you couldn't tell there had ever been a defect.

DAP All-Purpose Stucco Patch (Read-To-Use) is designed and recommended for use a a patch and repair product. The work as described, is outside of the scope of this product's intended use.