Rendered from docs/obligations/0029-what-headwater-query-takes.md in the Headwater corpus. Every document on this half of the site is typed by the taxonomy the descriptor names: corpus.json.

What headwater query takes

Context

Spec 6 lists the verb headwater query <expression>. No document states what an expression is: not a grammar, not an example, and not the set of things it selects over.

This is the sixth surface that has a required declaration and no stated form.

Obligation

The corpus owes the grammar of an expression and the set of things it selects over.

Discharge

The agent surface does not wait on it, because spec 5 names six tools in the query class and query is not one of them. The engine implements no expression. headwater query reports this gap and names the two reads that exist, which is the posture the resolver takes over a $package reference.