Rendered from docs/obligations/0081-a-published-read-set-never-says-which-instances-must-run-again.md in the Headwater corpus. Every document on this half of the site is typed by the taxonomy the descriptor names: corpus.json.

A published read set never says which instances must run again

Context

Spec 12 asks a run to report the union of its in-scope inputs, and the union is what headwater check publishes. A gate that holds the union against a later tree learns one thing: whether anything the run read has moved.

The same section also says that the engine derives the invalidated instances from a merge, and the union cannot support that. One changed document voids the instances that read it, and a union does not say which instances those are.

Obligation

The artifact that answers the second question is one row per instance rather than one per document. Over this repository that is 424 rows against 36.

Discharge

Either spec 12 states that the published artifact answers the coarse question alone, or the artifact carries a row per instance. The cost question of Q21 is then asked again at that size.