The sunk cost fallacy is taking into account costs that have already incurred and are unrecoverable when making your current decision.
Planning your decisions ahead of time is merely an optimization: in order to do it correctly, you have to plan each decision according to the world state that you expect to occur when that decision is to be executed.
In the cloak example, in world states where a decision between wearing the cloak and wearing a sweater is to be executed, the price of the cloak and the price of the sweaters are sunk costs, thus they should not affect the decision.
The sunk cost fallacy is taking into account costs that have already incurred and are unrecoverable when making your current decision.
Planning your decisions ahead of time is merely an optimization: in order to do it correctly, you have to plan each decision according to the world state that you expect to occur when that decision is to be executed.
In the cloak example, in world states where a decision between wearing the cloak and wearing a sweater is to be executed, the price of the cloak and the price of the sweaters are sunk costs, thus they should not affect the decision.