Function lower_agent_item_ir 

pub fn lower_agent_item_ir(
    agent: &AgentDecl,
    program: &CheckedProgram,
) -> IrItem

P6.10 (#1169): assemble an agent declaration into a real bynk_ir::IrItem::Agent — wires every prior slice’s own standalone constructor (lower_store_field_ir since P6.7, lower_invariant_ir/ lower_transition_ir/lower_commit_shape_ir since P6.8, lower_handler_ir since P6.9) rather than re-deriving any of their logic — the first IrItem variant assembled from other already-real IR data rather than lowered fresh from the AST by itself.

Computes state/store_cells/state_ty once and reuses them for every downstream call that needs them — the “future IrItem::Agent builder” every one of those constructors’ own doc comments already named as the job that would do this. store_cells is derived from state’s own already-lowered StoreKindIr::Cell entries, not re-resolved independently a second time from the AST — the one place this function could have re-derived something it already has, and doesn’t. invariants/transitions are lowered once, then passed to every handler’s own lower_handler_ir call, not just the store-writing ones: lower_commit_shape_ir only ever reads them for a Transactional shape, so a read-only or event-flushing handler simply carries the slices it was handed without using them, the same “pass what a callee needs, let it decide whether to use it” posture lower_commit_shape_ir’s own emits parameter already established.