Strategies as documents

A strategy expressible as data can be diffed, generated in batches and shipped in an extension. A grid document searches a rule Arvo implements over parameters you choose; it cannot contribute a rule, and a document naming a rule Arvo does not have is refused when the manifest is read, with the list of what it does have.

A rules document — thresholds over named signals — is read but not yet run: Arvo has no runner for one, and says so rather than dropping it.

A rule over a value that is not there is false

A signal may be absent: not published, or published with nothing in it. A predicate over an absent value is false — never zero, never true, never the last known value — and an empty rule set never fires either way. This exists because the alternative is quiet: an indicator with too little history is absent where it is computed and 0.0 by the time a rule reads it, and 0.0 is a value a threshold matches.