Start here: choose your first test

Loot, Vendors & Economy supplies trading, loot collection, buyback, market interfaces and integration contracts. Your game owns production inventory, currency, saves and authority. There are two different examples: the standalone sample bag and a buyer-owned inventory connection. Their wallets and stock are separate.

Install in your existing third-person project

1. Install the engine-compatible LootVendorEconomy plugin through Fab. For manual source installation, put its single folder in your project's Plugins directory and build Development Editor with Unreal's compatible C++ toolchain. The source plugin does not require you to write a gameplay C++ module.
2. In Edit → Plugins, enable Loot, Vendors & Economy explicitly. Keep IKRig, SQLiteCore, InterchangeAssets and ACLPlugin enabled. Restart when requested. Rowan is bundled; a separate QuartermasterRowanCore plugin is not required. The bundled Fallen Marauder retargeting assets reference the standard Third Person template mesh /Game/Characters/Mannequins/Meshes/SKM_Manny_Simple. Keep that template content for the supplied character examples, or replace those retargeting references when adapting them to your own characters. It is host template content, not a BIS UI dependency.
3. Use your existing Third Person level, with collision-enabled ground and a possessed local player. Enable Show Plugin Content in the Content Browser. The editable examples are under LootVendorEconomy → LootVendorEconomy → Examples.
4. For the ordinary standalone demonstration, press Play and use the sample bag's plain word buttons. For your own inventory, duplicate BP_LVE_BuyerStarter, BP_LVE_BuyerInventory and BP_LVE_BuyerCommerce into your project's Content before customizing them, and follow the illustrated setup below.

Manual source installation needs a build toolchain. An Epic-managed compiled installation follows Fab's installation workflow. A working editor preview does not prove that your own replacement assets are cooked into a packaged game.

Try the bag, vendor, loot and market

Standalone DEMO BAG

1. Each new Play session starts with an empty temporary bag and no demo Rowan, Marauder or display bench. The standard Third Person level, character and game mode remain in place.
2. Use the single ITEMS button to add the active demo collection. Press the same button again to remove its remaining temporary units. The bag shows one square slot for each active item definition, including an empty slot when that item is absent. The bundled collection has fifteen definitions; its slot count follows the collection rather than a fixed grid of twenty.
3. Use ROWAN and MARAUDER to spawn or remove their runtime demo instances. Repeated clicks must not create duplicates. End Play and start again, or reload the level: the demo actors begin absent. Their temporary instances are not saved into the level.
4. A chat-bubble indicator shows when Rowan is available. Approach and right-click to open trading. The standalone opens the vendor; in BIS UI, Rowan opens dialogue first and Trade opens the vendor. Vendor and market access remain in the commerce interface. The old coin prompt and bottom proximity bar are not part of the current standalone.
5. Buy only when wallet, stock and capacity allow it. Purchased and interchangeable demo units share compatible stacks. Selling or consuming an item uses its remaining demo units first. Removing ITEMS then removes only remaining demo-granted units, preserving purchased and unrelated quantities. It does not grant money or reset your wallet.
6. Use Buyback after a sale. Buy Back Selected restores one unit at its sale price; a refused buyback leaves wallet, stock and eligibility unchanged. Unique backpacks and equipment retain their identity. A sold demo identity bought back with your money becomes buyer-owned and is preserved by later demo cleanup.
7. Approach the Marauder and right-click to open loot. Take one or Take All. Accepted loot from the bundled demo Marauder is temporary and is removed with the remaining demo collection. Partial transfers credit only the quantity actually received. Take All processes stacks separately, so an accepted earlier stack remains if a later stack is refused. Buyer-owned loot providers do not become temporary just because their items share a name.
8. Open Market for the separate local preview. Drag an owned item to its posting slot and submit explicitly. Closing a draft does not post it. The optional sample buyer can complete a preview listing after about five seconds; it is not a real online purchaser.

The Ironbound Satchel and Field Repair Kit are excluded from current vendor offers and the active demo collection. Their legacy definitions and existing buyer-owned saved items remain compatible.

BIS UI and buyer persistence

BIS UI keeps its existing Inventory Kit bag, square cells, wallet and equipment integration. Its ITEMS button adds the same fifteen LVE demo definitions and quantities; WORLD ITEMS remains the separate physical prop and armour collection. Remove one collection before activating the other. The normal host bag capacity is not replaced by the standalone collection grid.

Only recorded temporary demo quantities are cleaned up at session end and startup. Buyer purchases, custom items, equipped gear, saves and providers remain intact. If cleanup cannot safely reduce bag capacity, or its ownership journal is missing or inconsistent, it refuses and reports the reason. Keep both inventory and ownership saves together; do not delete one file as a reset shortcut.

Generic LVE demo inventory controls stay disabled for connected buyer inventories and network play. A host such as BIS UI supplies its own recorded temporary collection controls. They remove exact owned demo quantities rather than resetting the connected inventory.

Buyer-owned inventory example

Place one BP_LVE_BuyerStarter near Player Start. Its inventory begins empty, with 500 minor units, two distinct item stacks and a four-unit limit per item. Match the currency IDs on its inventory and commerce components. Set Reward Item Id and a separate Loot Source actor. Startup connects once; failures return a reason.

With commerce windows closed, G grants one configured reward and H consumes one. The wallet stays unchanged. V opens the registered vendor; O registers the separate loot actor and L opens it. M opens the separate market preview. F8 disconnects. Successful purchases and loot already transfer their items: do not grant them again from a notification.

Controls and window behavior

Text search and numeric entry use the platform's normal text-input path; an on-screen gamepad keyboard is your host/platform integration. The buyer starter's G/H/V/M/O/L/F8 callers are editable examples, not universal keys installed into every game.

Appearance, settings and feature switches

Use window settings to adjust scale, width/height, back glass, surfaces, borders, background art, portraits and inspection. Changes apply live and save to GameUserSettings.ini after approximately 0.35 seconds without another change. Closing the window does not undo them. These are presentation saves, not saved money or inventory.

Reset Standard Appearance restores appearance/inspection defaults and the three window positions. It does not reset a production economy or erase the saved bag visibility preference. Standard, Compact and Wide are presentation profiles. Inspect your actual player viewport after changing scale or opacity.

For project-wide switches, edit your project's Config/DefaultGame.ini and restart Play/module startup. Set only the keys you need; these are separate from each player's saved appearance.

[LootVendorEconomy.Features]
bEnableDemoTools=False
bEnableTestBag=False

[LootVendorEconomy.Preview]
bEnableAutomaticPreview=False

Vendor portraits capture the selected actor's animated face and shoulders only while visible. A head socket is preferred; bounds provide fallback framing. Custom skeletons/materials need their own visual check. Loot portraits use a separate full-body framing path.

Add your own items and connect your own inventory

1. Copy the buyer examples into your game. In BuyerCommerce's Items array, add a unique Item Id and Offer Id, readable Display Name, optional Description/Icon, matching Currency Id, purchase/sale prices and Initial Stock. The sample IDs are examples; your provider need not use them.
2. For loot, add matching Loot entries with item IDs and quantities. Assign a separate source actor and a unique source identity; registering it does not open its window or transfer anything.
3. Configure BuyerInventory's Currency Id, Balance Minor Units, Counts, Stack Capacity and Maximum Per Item. On a placed starter, inspect its component instance settings as well as the copied component's defaults.
4. Connect your actual inventory component through ConnectBuyerInventory. Branch on Return Value and show Failure. Query the registered source before displaying prices/counts. Use the illustrated graphs below to retain the success/refusal paths.
5. Replace the parent/example Read, Room and Commit operations with your real inventory callbacks. Read is an observation; Room must obey your capacity policy. Commit must compare the complete Expected state and apply Desired atomically. False means no mutation; true means the change already happened.
6. Use inventory-change snapshots to refresh your UI. Do not grant another unit from a receipt or notification. Use Add LVE Inventory Item / Remove LVE Inventory Item only for separate gameplay rewards or consumption; preserve returned failure messages.

Keep callbacks synchronous. Do not use Delay, start another inventory/commerce mutation during a callback, or substitute the demo bag when the owner is lost. Your game supplies saving/loading, server authority and adapters to other inventory frameworks. Keep operation IDs stable for an identical uncertain retry; a different action gets a new ID.

The component example retains twenty eligible buyback sales separately from up to 4096 successful operation receipts. A full receipt store refuses new operations; it does not silently evict replay protection. Repeated successful requests return their existing receipt rather than granting twice.

Customize the included preview assets

For the active fifteen-definition bundled demo collection, use LootVendorEconomy.PreviewAssets in DefaultGame.ini. CommerceIcon, SettingsIcon, CloseIcon, PickupIcon and CurrencyGoldIcon / CurrencySilverIcon / CurrencyCopperIcon take disk-resource paths relative to Resources/Preview. Sample inventory icons use Resources/Preview/Items/<ItemId>.png. Keep replacement disk resources in packaging/staging.

Inspection mesh keys include FlyAgaricMesh, SilverbladeMesh, NightfallMesh, IronboundSatchelMesh, WeatheredTonicMesh, CobaltWhetstoneMesh, CobaltShardMesh, RangersRopeMesh, WardensLanternMesh, FieldRepairKitMesh, CrackedTankardMesh, TornBootMesh, CopperOreMesh, CopperBarMesh, CopperShardMesh and CobaltNodeMesh. Their values are Unreal object paths, not filesystem paths. For example:

[LootVendorEconomy.PreviewAssets]
WeatheredTonicMesh=/Game/MyItems/SM_MyTonic.SM_MyTonic

These overrides change existing sample presentation. They do not add a new vendor offer or create a general item-definition registry. Include the replacement mesh, materials and textures in your host cook. A missing mesh falls back to 2D inspection.

Change fixed sample prices or loot quantities

Create an LVE Vendor Definition and/or LVE Loot Table Definition Data Asset and select it through LootVendorEconomy.PreviewData in DefaultGame.ini. Creating the asset alone does not activate it.

[LootVendorEconomy.PreviewData]
VendorDefinition=/Game/LVE/DA_MyPreviewVendor.DA_MyPreviewVendor
LootTableDefinition=/Game/LVE/DA_MyPreviewLoot.DA_MyPreviewLoot

The vendor overlay is restricted to existing sample IDs: VendorId Rowan; OfferId matching ItemId; CurrencyId Gold; finite stock 0–1,000,000; nonnegative buy/sell prices bounded against overflow. A stocked offer needs a positive buy price. Leave Icon unset and Unlimited Stock off. Display name/description may be overridden; omitted entries retain defaults.

The fixed loot overlay accepts only WeatheredTonic and CobaltShard with equal minimum/maximum quantities 1–1,000, Weight 1 and no icon/text overrides. It changes fixed stack counts, not weighted/random loot generation. Invalid or duplicate rows reject the entire selected asset's overlay. Restart Play to load edits; an active offer is not repriced live.

For new IDs, different art, your own capacity/wallet or broader loot behavior, use the buyer provider workflow above. The fixed preview overlay and general provider contracts have different limits. The sample display converts 100 copper to one silver and 100 silver to one gold; transactions use integer minor units.

Connect an online auction economy

Opening Market does not authenticate a player. Local vendor/loot and bag-grant demonstrations are disabled in network games. Online auctions use a separate server-owned account/escrow path.

1. Add LVE Auction Connection to the owning PlayerController, replicated and owned by that player. Do not put it on a shared world actor.
2. At trusted server startup, register tradable item IDs and install the intended provider. The editable BuyerCommerce auction callbacks cover account reads, listing queries, command commits and expiry; ConnectBuyerAuctionAdapter registers that adapter before player requests.
3. After your server verifies login, Bind Authenticated Account with the stable account ID. Provision Session Account initializes only a new account; returning players bind to their existing account without another grant. Never use an unverified client name as identity.
4. The owning client submits LVE Auction Command Request with a fresh operation GUID for a new action. Retry an uncertain result with the same GUID and unchanged request. On Response supplies the confirmed receipt, private state and page. Do not debit or grant speculatively.
5. Query again for current listings. The screen supports bounded pages and refreshes while open. Expired listings whose destination cannot accept proceeds/items remain Pending Settlement with escrow preserved; the host must resolve the capacity problem.

Persistence and recovery boundaries

The bundled server provider uses SQLiteCore; it is not a hosted database service. Dedicated/listen server worlds select durable storage, normally Saved/LVE/Marketplace.sqlite. Ordinary standalone/PIE previews are isolated in memory. Configure before accepting requests:

[/Script/LootVendorEconomy.LVEAuctionServerSubsystem]
bUsePersistentStorage=True
DatabaseRelativePath=LVE/Marketplace.sqlite
CommissionBasisPoints=1200

1200 basis points is 12%; an existing durable ledger retains its recorded fee policy. State and operation receipt commit together. Storage failure refuses the request instead of falling back to an empty economy. Preserve the database on a failed load. Stop the server before making a consistent backup; off-machine backup, authentication, hosting and recovery administration are your responsibility.

The bundled provider has bounded capacity: 128 accounts, 512 active/pending listings, 256 item types per account, an 8 MiB serialized ledger and 4096 durable receipts across the database. Restart does not reset receipt capacity. Do not delete receipts or escrow to make space. A long-running or cross-server production economy needs your own authoritative provider/storage policy.

For an economy you already own, install ILVEAuctionProvider through SetProvider, or the documented Blueprint adapter. Commit inventory, wallet, listing, escrow and receipt in the same authority/transaction. Do not copy balances back into the sample ledger after each request. These callbacks are synchronous; avoid remote database I/O that blocks the game thread.

Content, cooking and your packaged game

The delivery is one LootVendorEconomy plugin. Unreal assets live below Content/LootVendorEconomy, including the three buyer examples, Rowan and Fallen Marauder content, inspection meshes/materials and sample icons. Resources/Preview supplies disk UI images and contact samples; Config and Docs contain distribution/configuration guidance.

The default cook manifest names the bundled inspection meshes, two scene-capture materials, Marauder mesh/material/legacy replacement and Rowan profile/mesh/idle roots. Unreal follows their dependencies. It does not recursively cook every directory or discover arbitrary INI replacements. Host never-cook exclusions still apply. Disk resources are staged separately as NonUFS files.

1. Keep a cooked reference or explicit host cook rule for copied buyer examples, custom catalogs, icons, meshes and materials. An INI object path is not proof that an otherwise unreferenced asset was cooked.
2. Package the supported target. Inspect its actual staged plugin/resources and cooked asset output. Run the packaged game and repeat vendor, loot, capacity/refusal, cleanup and inspection tests.
3. If you deliberately take over default asset selection, set bIncludeDefaultRuntimeAssets=False under LootVendorEconomy.Cooking. Supply equivalent rules for every feature you keep. Opting out does not remove assets selected by another map/reference.

Disable unwanted example features before removing assets, and test a clean packaged host. Your project may omit teaching examples it never references; do not remove a resource needed by an enabled feature. The plugin is validated on the Unreal 5.8 line for Win64; custom assets, rigs and other platform/host combinations need their own checks.

Included content: 114 Unreal assets, including the three editable buyer Blueprints. Optional item icons for Fly Agaric, Nightfall, Silverblade and the Vintage Leather Backpack can be assigned to Icon in your buyer commerce Items entries or custom vendor/loot definition. The unbranded Copper Bar mesh is an optional CopperBarMesh override; see Docs/PREVIEW_ASSETS.md for its asset path. These alternatives do not add items to the demo collection. Download the complete asset manifest for exact delivered paths and hashes.

If the first test does not work

Check your integration before shipping

• Try one successful purchase/sale/buyback and one refusal. Compare stock, wallet and owned quantity before/after. Replay the identical completed request: it must not transfer twice.
• Try full distinct-stack capacity and a per-item limit. A refused reward or loot stack must not change unrelated state. Check partial Take All explicitly.
• Close/cancel windows and posting drafts; verify no unintended transaction. Destroy a source/owner, disconnect twice and end play. Owner loss must refuse rather than switch to sample inventory.
• Check your own item text, icons, 3D meshes, portraits and window readability. Test real controls and the packaged game; example API checks do not certify an arbitrary host.
• For online auctions, test account ownership, uncertainty/retry, reconnect, persistence and blocked settlement with your actual server/provider. Local vendor inventory and auction escrow are separate unless your host explicitly connects their authorities.

Use the illustrated sections below for exact editable graph paths, nodes, pins and expected results. The native appendix provides equivalent public C++ connections. If requesting support, include your Fab version, Unreal version, the failing workflow and its Failure message; do not share login secrets or private account data.