## Summary Stacked on #2676. Review that first; this PR's diff is against it. Items players sell to NPC vendors go into the vendor's buyback (`ShopBuy`) pack. That pack was purged only when someone opened the buy menu, so a vendor that players sold to but never bought from grew without limit. - A server operator reported 250k+ items piling up from players crafting and selling on a macro. - Every one of those items was saved. - Purging or deleting that vendor then sent one remove packet per item to every nearby client and disconnected them. The behavior is inherited from RunUO. - **`VendorBuybackPack`** replaces the plain backpack on `Layer.ShopBuy`. - It opts in to `SkipsChildSerialization`, so buyback items are never saved. - Its contents are private like any container's, so removing them reaches only the vendor (no client) and openers. Purges and deletes send nothing to bystanders. - **Capacity.** The buyback holds at most `250 − buy-list entries` items, which is what the buy gump can show. The oldest items are evicted first. At capacity 0 the sold item is consumed and the seller is still paid. - **Purge on the restock grid.** - `Restock()` empties the buyback. - A purge-only timer, armed on the first sale, covers vendors nobody buys from. It is due at the next restock boundary after now, so a vendor whose restock hasn't run for hours doesn't purge an item the moment it's sold. - The timer never restocks, so stock doubling and halving is unchanged. - The old per-item one-hour `LastMoved` check is gone. - **Existing saves.** A legacy `ShopBuy` pack is replaced on the first tick after load. Thanks to #2676, deleting a pack of 250k+ items takes well under a second. **Behavior changes for shard operators:** - A buyback item lasts until the next restock boundary (at most `RestockDelay`), not one hour after its sale. - A vendor that changes maps drops its buyback. - A buy window that is open during a purge can show a row whose item is gone. Buying that row does nothing, and reopening shows the current list. ## Test plan - [x] `VendorBuybackPackTests`: evicts oldest first; capacity 0 consumes the item; purge; a stale front entry can't spin eviction - [x] `VendorBuybackTests`: - purge due time stays on the restock grid, including a stale restock and a restock time in the future; - partial stack sale: the split goes to buyback and the seller keeps the remainder; - zero capacity consumes the item and still pays; - restock purges and clears the timer, and the next sale re-arms it; - deleting the vendor cancels the timer; - a legacy 20k-item pack is replaced. - [x] UOContent.Tests and Server.Tests green; schema generator clean - [x] Manual in-game pass: - sell and buy back, including a partial stack; - over-capacity sale; - purge with no buyer; - `[restock`; - vendor facet change; - restart; - legacy save with a large `ShopBuy` pack; - mass selling with bystanders present; - deleting a vendor with a full buyback. |
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| FAQ.md | ||
| GEMINI.md | ||
| global.json | ||
| LICENSE | ||
| ModernUO.slnx | ||
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| publish.sh | ||
| README.md | ||
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ModernUO

Ultima Online Server Emulator for the modern era!
Requirements
Supported Operating Systems
Required Frameworks
All Operating Systems
Windows
Hardware
| Use | vCPU | RAM | Storage |
|---|---|---|---|
| Development / test | 2 dedicated | 2 GB | SSD |
| Small live shard (< 50 concurrent) | 4 dedicated | 4 GB | NVMe |
| Medium (50–200) | 4–8 | 8 GB | NVMe |
| Large (200+) | 8+, high clock | 16 GB+ | NVMe |
See dev-docs/server-requirements.md for more information.
Development
Supported IDEs
Getting Started
- Install prerequisite requirements
- Clone this repository (or download the latest):
git clone https://github.com/modernuo/ModernUO.git
- Open
ModernUO.slnto start developing
Building/Publishing
Interactive Mode (Recommended for new users)
Run ./publish.cmd (Windows) or ./publish.sh (Linux/macOS) with no arguments to launch the guided build tool. It will:
- Check prerequisites (.NET SDK, native libraries)
- Walk you through configuration and platform selection
- Build and publish the server to the
Distributiondirectory - Show deployment instructions for cross-compiled builds
Command Line
./publish.cmd [release|debug] [os] [arch]
os- Supported operating systemsarchx64- Intel/AMD 64-bitarm64- ARM 64-bit
Linux Prerequisites
Fedora, CentOS, RHEL, AlmaLinux, Rocky, etc
dnf upgrade --refresh -y
# RHEL-family distributions (CentOS Stream, AlmaLinux, Rocky, RHEL) need CRB and EPEL enabled.
# Fedora skips this block.
dnf install -y dnf-plugins-core
dnf config-manager --set-enabled crb
dnf install -y epel-release
# Prerequisites
dnf install -y findutils libicu libdeflate libargon2 tzdata
Ubuntu, Debian, etc
apt-get update -y
# The ICU runtime package carries the ABI version in its name (libicu74, libicu76, …) and has no
# stable alias, so match it by pattern rather than pinning a release-specific name.
apt-get install -y '^libicu[0-9]+$' libdeflate0 libargon2-1 tzdata
Only the runtime libraries are needed — the -dev/-devel packages are not. Run
./build-tool --check-prereqs to check the current machine and print the exact packages your
release needs.
zstd is not listed because ZstdNet bundles libzstd for every platform, and liburing is not
listed because IORingGroup issues io_uring syscalls directly.
If the shard's configured time zone is a legacy alias such as US/Eastern, Debian 12 and Ubuntu
24.04 also need tzdata-legacy. See Platform Prerequisites
for what each dependency is for and what breaks without it.
OSX Requirements
brew install icu4c libdeflate argon2
Running the Server
- Follow the publish instructions
- The
Distributiondirectory is portable — copy it to your production server for deployment - Run
ModernUO.exeordotnet ModernUO.dllfrom theDistributiondirectory - On first run, the server will prompt you to configure game data file locations
Troubleshooting / FAQ
- See FAQ
Want to sponsor?
Thank you for supporting us! You can find out how by visiting the sponsors page.
Collaborators
Thanks
- RunUO Team & Community
- Voxpire, the ServUO Team & Community
- Karasho, Jaedan and the ClassicUO Community
Development Tools & Plugins provided with ♥ by
Code Signing Policy
Free code signing provided by SignPath.io, certificate by SignPath Foundation.
This program will not transfer any information to other networked systems unless specifically requested by the user or the person installing or operating it
Teams & Roles
Approvers & Committers: Development Team