Explanation

Design and semantics of Shifty’s compiler, evaluator, evidence model, and experimental repair layer.

How shapes are compiled	How shapes are compiled, how rules feed inference, and how algebraic findings differ from the W3C report path.
Shapes graphs and data graphs	The distinction between the shapes graph and the data graph, and the separate question of which triples are visible during evaluation. The most common source of a validation that passes for the wrong reason.
Recursion and stratification	Cyclic shape references have no answer in the SHACL spec. What Shifty chose, why validation and inference use opposite fixed points, and why some schemas are refused.
Why evidence	Why the validator keeps its derivation, what “canonical” evidence means and why it deliberately omits things, and what it honestly cannot explain.
Evidence performance	Choose an evidence entry point using measured runtime and size costs.
Why repair computes but does not choose	Experimental. Repair as the abductive dual of validation, and why the library computes the space of fixes but refuses to choose one.