phosphor-rules

Phosphor's single rule engine: one composable match-expression language, one pluggable action set, one serialization format, and one evaluation pipeline with a match cache. Both the KWin effect and the daemon link this one implementation so match code lives in exactly one place. RuleEvaluator::resolve() walks the rule set in descending priority and accumulates the first action that fills each slot, and RuleSet reads and writes rules.json at a fixed schema version, dropping malformed rules with a diagnostic. Actions are slot-based descriptors registered in an ActionRegistry, so a new action type — setting a scrolling template, pinning a strip axis — is a registration rather than an engine change.