---
id: 5745e0d5-e98d-458e-bd00-a58304877f07
type: solution
title: "Fix backpack AE slot bonus not applying"
tags: [vagabond-rpg, foundry-vtt, active-effects, fix]
importance: 0.6
confidence: 0.8
created: "2025-12-22T20:42:05.466526+00:00"
updated: "2025-12-22T20:42:05.466526+00:00"
---

Active Effects modifying itemSlots.bonus were being overwritten by prepareDerivedData(). Fixed by changing 'this.itemSlots.bonus = totalBonus' to 'this.itemSlots.bonus += totalBonus' so AE contributions are preserved. Also fixed backpack.json effect _key referencing wrong item ID.