Change 6901

```Originally Posted : Fri Jul 31 09:09:52 2026
Posted by : Ghyath
Title : Shop stock
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With introduction of gen_eq equipment grind became "the thing", but the
shop stock used to basically just destruct latest 200 items while keeping
the first 200 items for whole boot duration.
I made a change how shop stock is handled and the long story short,
shopkeepers try to always preserve valuable items of each rarity
independently on their actual "age".
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