pick up keys and items into an inventory the player carries

Inventory is a warehouse-backed SCRIPT PATTERN. Store held items as a record keyed by item type, add with ctx.warehouse.append or increment on pickup, read with get or query to gate actions, and project the counts to a HUD panel. There is no inventory component; the durable warehouse record IS the inventory.

track how many potions or ammo the player is holding

Inventory is a warehouse-backed SCRIPT PATTERN. Store held items as a record keyed by item type, add with ctx.warehouse.append or increment on pickup, read with get or query to gate actions, and project the counts to a HUD panel. There is no inventory component; the durable warehouse record IS the inventory.

use or consume an item from the inventory

Inventory is a warehouse-backed SCRIPT PATTERN. Store held items as a record keyed by item type, add with ctx.warehouse.append or increment on pickup, read with get or query to gate actions, and project the counts to a HUD panel. There is no inventory component; the durable warehouse record IS the inventory.

backpack inventory of potions and ammo the player carries

Inventory is a warehouse-backed SCRIPT PATTERN. Store held items as a record keyed by item type, add with ctx.warehouse.append or increment on pickup, read with get or query to gate actions, and project the counts to a HUD panel. There is no inventory component; the durable warehouse record IS the inventory.

Inventory item pickups keys and equipping

The recipe

Author with project_apply_script_semantic_patch using the ai_safe op pack. Held items live in a warehouse store (default storeKey:"inventory", recordKey:"player"), one field per item type.

Make each world pickup an entity tagged by item type with a trigger ColliderComponent (collision:"trigger").
On pickup, addTriggerHandler { "handlerKey":"onPickup" }. Inside it: incrementNumericState { "field":"keys", "by": 1 } to add a counted item, or writeTypedStateValue to set a unique key you either hold or do not; then despawnEntity { "reason":"picked_up" } to remove the world item.
For a list of distinct items, append to an array field with ctx.warehouse.append in a whole-body GessaScript body (replaceScriptFromGessaScript); read the whole record back with ctx.warehouse.get or filter with ctx.warehouse.query.
Gate an action on holding an item: readTypedStateValue the item field, and only open the locked door (see doors-buttons-and-interactions) or fire the weapon when the count is above zero.
Consume or equip: on use, incrementNumericState the field by -1 (consume) or writeTypedStateValue an equipped field to the item id (equip). Project every count to the HUD with wireHudStateBinding or ctx.ui.setWidgetValue.

Pitfalls

Keep the inventory in the warehouse, not on a component; a count written only on the entity is lost when the entity despawns or the player reloads.
ctx.warehouse.* writes are prefetch-then-drain and authority-gated (persistence.prefetch_only); mutate on the server, and read the field you intend to change in the same handler so the drain is deterministic.
Decrement guardedly: check the count is above zero before consuming, or you create negative inventory.
For stackable items increment a number; for unique items (a named key) set a boolean or an id, not a counter.

Verify

simulation_run (qa.run.start) to prove a pickup raises the count, using an item lowers it, and a gated door opens only while the key is held.
project_get_graph_snapshot to confirm the pickup triggers and handlers exist.

The recipe

Pitfalls

Verify

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