Interface RuleScopeAlpha

Resolves subject slots to values at evaluation time.

A CompiledRule receives a RuleScope and reads each slot it needs (e.g. the current user, the object in context). Each scope resolves slots its own way: by walking the DOM, by consulting a session-wide default, or by reading from a fixed value bag. The caller picks which strategy when they build the scope with scope.

One method, get(slot). A primitive that needs more than one slot calls get multiple times.

Each slot resolves in order from most specific to least: a per-call override on scope wins first, then the closest DOM ancestor that registered a value through provideSubject, then a session-wide default registered through registerSubject. If none of those answer, get returns undefined and primitives reading the slot return false.

Resolution is pull-based, not reactive: a RuleScope answers the current value on each get call but does not notify when a value changes. Re-evaluating a rule when its inputs change is the caller's responsibility.

Example

Reading a slot inside a primitive's predicate

type OlderThanArgs = { days: number };

const olderThan = definePrimitive({
    id: 'limetech.object-older-than',
    reads: ['limeobject'],
    build: ({ days }: OlderThanArgs) => (scope) => {
        const obj = scope.get('limeobject');
        if (!obj) return false;
        return daysSince(obj.createdtime) > days;
    },
});

See

• scope, the only supported way to construct a RuleScope.
• SubjectRegistry, what slots exist and what they return.