Function carry_block_identity_env 

pub(crate) fn carry_block_identity_env(
    mstore: &Store,
    block_id: &str,
    env_vars: &mut HashMap<String, String>,
)

Identity M4b-2 (spec §6.5.8): carry block_id’s row UID and token into the env of a controller that builds its own (App Server, ACP) instead of going through build_persistent_spawn_env. Same resolution and the same reserved-value rules as that builder (stale values are overwritten, or removed when the block has no row). A synchronous store read and an idempotent token mint, so on a multi-thread runtime worker it runs under block_in_place, as eager resume does (incident #1782).