One point to make is that the outcome of any cabinet decision about individual budget measures is published as part of the budget documentation, so the result of the green brief, if you like, as reflected in the government decision, is a matter of public record. Individual measures are published in budget papers. There are also portfolio budget statements that accompany the budget papers. They show individual measures and the performance measures that are attached to them so Parliament can judge the success of any new program or any new spending.
What is a matter of internal government record, if you like, is the information that's produced for deliberative processes, but the outcome of those deliberative processes is a matter of public record, with a fair degree of granularity.