Dev Shard

Dev Shard

The client needs a server to talk to. The dev shard is a local ModernUO instance running against the same UO install the client reads, listening on 127.0.0.1:2593 as GUO Dev: loopback only, so no other machine can reach it unless you open it on purpose (below). It is a development dependency: nothing in godot\GUO\ knows it exists. Source of truth: tools\modernuo\README.md.

Pinned at	d4531cd94 (2026-09-30), UO_SHARD_REF in config.bat
Runtime	.NET 10 SDK (ModernUO's requirement, not the client's)
Checkout	tools\modernuo\src\, gitignored, about 1 GB built
Licence	GPL-3.0. Not vendored: fetched at the pin.

Use it

launchers\shard\fetch.bat      REM clone at the pin and apply the patches   (once)
launchers\shard\build.bat      REM publish release win-x64                  (once, ~2 min)
launchers\shard\run.bat        REM run it; Ctrl-C stops it
launchers\shard\populate.bat   REM generate the world                       (once, ~10 min)

Then, in another terminal, launchers\game\play.bat.

Auto account creation is on: the first login with any name and password creates that account. accountHandler.maxAccountsPerIP is 4 in the template rather than ModernUO's 1, because the scripted runs put several clients on one machine. Put it back to 1 on a shard anyone else can reach.

Populating the world

A new ModernUO save is the real map with nobody on it: no creatures, vendors, signs or doors. What fills it in are in-game commands, so populate.bat logs the owner account in with the client itself and types them: the list AdminGump's "Do everything" button runs, in its order ([GenerateSpawners, [Decorate, door, sign, moongate and teleporter generation, [Save). Spawners and decorations alone are not a world: a town generated without DoorGen has empty doorways, which is how that was found. The shard saves the result; delete Saves\ and it has to be run again.

Accounts

Account	Role
The owner (UO_SHARD_OWNER, guoprobe by default)	Made or raised to owner on a headless boot by patch 0001. playtest.bat, populate.bat and the session lane of multi_client.bat log in as it.
The trade partner	The second client playtest.bat starts to trade with; the reason maxAccountsPerIP is above 1.
guoeffects, guohighlight, guosweep (UO_SHARD_GM_ACCOUNTS)	Created with game master access on a headless boot, one per multi_client.bat lane, because the shard refuses a second character from one account and [go takes staff access. world_parity plays as the last of them.

Where the passwords are

There is no default password. The first launchers\shard\run.bat generates two random ones, for the owner (UO_SHARD_OWNER_PASSWORD) and for the game master accounts (UO_SHARD_GM_PASSWORD, shared by all three), and writes them to a file of your own:

%LOCALAPPDATA%\GUO\shard\secrets.bat      (or <UO_WORKSPACE_DIR>\shard\secrets.bat)

It is outside the repository (and secrets.bat is gitignored besides), never printed in full, and never copied into a run folder. Every launcher reads it after config.bat, so playtest.bat, populate.bat, multi_client.bat and the tools log in with it without being told; open the file when you want to log in by hand. At every boot the shard sets the owner and game master accounts to these passwords, so a world made before them stops taking the old ones.

• New passwords: delete the file and run launchers\shard\run.bat again.
• Your own password: set UO_SHARD_OWNER_PASSWORD (or UO_SHARD_GM_PASSWORD) in config.local.bat; that wins over the file.

What is committed, and why

The checkout is gitignored. What is committed reproduces it:

patches\	Three small dev-only changes: the owner and GM accounts made on a headless boot, a settable update range, and spring on Felucca. See tools/modernuo/README.md.
config\modernuo.template.json	The full server configuration with @UO_CLIENT_DATA@, @UO_SHARD_NAME@, @UO_SHARD_LISTENER@ as placeholders; expansion.json pins Endless Journey, which a 7.0.x client expects.
configure.py	Fills the templates into src\Distribution\Configuration\ on first run, through tools\guo\config.py. Writes only files that do not exist, except the listener, which it sets to UO_SHARD_BIND at every run. Generates the passwords.

Bugs we find in ModernUO are reported upstream rather than patched for long: our multi-tile fix became ModernUO's own (#2682, fixed in #2685), so the pin moved past it and the patch was deleted.

Opening it to the LAN

The shard binds to 127.0.0.1 (UO_SHARD_BIND in config.bat), so only this PC can connect. To let a phone or another PC on your network in, do it on purpose, in your own launchers\_shared\config.local.bat:

set "UO_SHARD_BIND=0.0.0.0"

(or this PC's LAN address alone), then restart launchers\shard\run.bat; it says when the shard is reachable from other machines. Pass --host <this PC's address> to the client on the device (tools\android\README.md). Anyone on that network can then reach the login screen, so keep the generated passwords rather than setting simple ones, and look at accountHandler.enableAutoAccountCreation and maxAccountsPerIP in the generated modernuo.json. Remove the line and restart to close it again. Do not put an address in a committed file.

The editor's private instance

The editor's live tier and the world export use a second, private ModernUO instance on port 2594 (tools\editor_shard), so editing the map never disturbs whoever is playing on the dev shard. See Editor.