Function check_plan 

pub fn check_plan(
    c: &Circuit,
    plan: &FusionPlan,
    rules: &[Rule],
    families: &Families,
    settings: &BTreeMap<String, String>,
) -> Result<PlanPipelines, PipelineError>

2026-10-02: Check plan of c: every node’s declared pipeline against its requirement under settings, the plan’s groups’ rules being among rules.