When is a delta no longer enough?#
When the person's starting point is too far from the present. An engineer back after three months, a new joiner, a reviewer after a major refactor: forty deltas explain nothing to any of them. State reconstruction rebuilds situation awareness instead, which Mica Endsley's model describes in three levels: perceiving what is there, understanding what it means, and projecting what happens next.
What does reconstruction include that a delta does not?#
The beliefs to discard. Telling someone what is true is easier than telling them which parts of their old mental model are now wrong, and the second is what prevents the error. A reviewer acting on a model that was accurate six weeks ago can approve exactly the wrong things, with confidence.
For a returning owner, needing reconstruction is the visible cost of comprehension debt.