FA-86184 / Game economy crafting balance / Member archive

Inventory stack insertion: Top-up fills later slots first · case 04

Loot lands in the last partial stack instead of the first.

Member previewVariant 4 · 3 implementations · 8 checks per implementation

Case contract

slots = list of None or [name, count]; names are case sensitive. First top up partial stacks (count < max_stack) of the same item in slot order, then fill empty slots in order with new stacks of at most max_stack. Reserved placeholders [name, 0] count as partial stacks. Legacy stacks above max_stack are left untouched. Returns {slots, leftover}.

Why this case matters

Game economies leak or destroy currency when one crafting or pricing rule is off by one boundary, rounding stage or state update; the defect is observable in exact integer outcomes.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
two partial stacks #1	`{"leftover": 0, "slots": [["Arrow", 18], ["Arrow", 19], null]}`	`{"leftover": 0, "slots": [["Arrow", 20], ["Arrow", 17], null]}`	Failed

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This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

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