One file holds every setting with its default: launchers\_shared\config.bat. Your machine's values go in launchers\_shared\config.local.bat (gitignored, copied from config.local.bat.example). Every launcher, tool and runtime resolves the same values in the same order:

1. an environment variable already set in the shell;
2. config.local.bat, yours;
3. config.bat, the committed defaults;
4. an optional central shared config named by UO_COMMON_CONFIG, for a machine hosting several projects.

On Linux and macOS the .sh launchers read the twins, config.sh and config.local.sh (from config.local.sh.example): the same keys in : "${NAME:=VALUE}" lines, resolved in the same order, with forward-slash paths. tools\launcher_lint fails a config.sh whose keys differ from config.bat's, so a new setting goes in both.

tools\guo\config.py parses the same files when a tool runs outside a launcher (the .bat pair on Windows, the .sh pair elsewhere), so the editor, an agent and CI see the same paths. No launcher, tool or runtime hardcodes a path. CI rejects a commit that puts a machine path anywhere but config.local.bat.

common.bat derives UO_ROOT, UO_GODOT_PROJECT, UO_SOURCES, UO_TOOLS, UO_DOCS, UO_BUILD, GODOT_EXE and GODOT_CONSOLE from these; they are not settings.

Key	Default	Meaning
GODOT_VERSION	4.7.2-stable	Pinned engine version the bootstrap fetches.
GODOT_FLAVOR	mono_win64	Must be a mono/.NET flavour; the plain build cannot run C#.
GODOT_EXE	unset	Override the engine executable. Leave unset to use UO_GODOT_HOME.
UO_GODOT_HOME	tools\godot	The folder holding the pinned release folder. A git worktree without one uses the main checkout's.
UO_UPSTREAM_DIR	sources	The folder holding ClassicUO. A git worktree without one uses the main checkout's (MSBuild too).

Key	Default	Meaning
UO_CLIENT_DATA	none, required	Folder of your UO install (holds tiledata.mul and the rest). Read in place, never written.
UO_CLIENT_VERSION	7.0.107.76	The client version of that install; 01_verify_client_data.bat reports what it sees.
UO_CACHE_DIR	%LOCALAPPDATA%\GUO\cache	The runtime decode cache. Safe to delete.

Key	Default	Meaning
UO_SHARD_HOST	127.0.0.1	Host the client logs in to.
UO_SHARD_PORT	2593	Its port.
UO_SHARD_NAME	GUO Dev	The name the local dev shard announces.
UO_SHARD_REPO	https://github.com/modernuo/ModernUO.git	Where launchers\shard\fetch.bat clones from.
UO_SHARD_SRC	%UO_ROOT%\tools\modernuo\src	The ModernUO checkout (gitignored, about 1 GB built).
UO_SHARD_DIST	%UO_SHARD_SRC%\Distribution	Its built distribution.
UO_SHARD_BIND	127.0.0.1	The address the local dev shard listens on: loopback only. 0.0.0.0 opens it to the LAN, on purpose (Dev Shard).
UO_SHARD_OWNER	guoprobe	The account the headless boot raises to owner, and the one playtest.bat and populate.bat log in as.
UO_SHARD_OWNER_PASSWORD	none: generated	Its password. The shard's first run generates it into the per-user <workspace>\shard\secrets.bat (Dev Shard); set it in config.local.bat to choose your own.
UO_SHARD_GM_ACCOUNTS	guoeffects,guohighlight,guosweep	Comma-separated accounts the headless boot creates with game master access, one per multi_client.bat lane.
UO_SHARD_GM_PASSWORD	none: generated	The game master accounts' shared password, generated with the owner's.
UO_SHARD_UPDATE_RANGE	72	The shard's update range in tiles (patch 0002-settable-update-range), so a zoomed-out client sees the whole screen.

Key	Default	Meaning
UO_WORLD_PROJECT	%UO_ROOT%\build\world\default	The world project folder the editor edits and tools\world exports.
UO_EDITOR_LIVE_HOST	127.0.0.1	The bridge the editor's live tier connects to (ADR-0012).
UO_EDITOR_LIVE_PORT	2595	Its port.
UO_EDITOR_NAME	%USERNAME%	The name an editor announces on the bridge.

Key	Default	Meaning
UO_ANDROID_SDK	%LOCALAPPDATA%\Android\Sdk	Android SDK with platform-tools and build-tools.
UO_ANDROID_JDK	%JAVA_HOME%	A JDK 17.
UO_ANDROID_KEYSTORE	%APPDATA%\Godot\keystores\debug.keystore	The debug keystore; run.py keystore makes it.
UO_ANDROID_KEYSTORE_USER	androiddebugkey	The standard Android debug alias.
UO_ANDROID_KEYSTORE_PASSWORD	android	The standard Android debug password. Not a secret; a release keystore is your own.
UO_ANDROID_PACKAGE	org.guo.client	The application id.
UO_ANDROID_DEVICE	empty	An adb serial. Empty means the single device in state device; set it with two attached.
UO_ANDROID_CLIENT_DATA	/sdcard/Android/data/%UO_ANDROID_PACKAGE%/files/uo	Where run.py push puts the UO data on the device, baked into the APK as --client-data.
UO_ANDROID_SECOND_DISPLAY	empty	Force a display id for the second screen; empty lets the client pick (see Dual Screen).

Key	Default	Meaning
UO_WEB_PORT	8060	Port launchers\web\serve.bat serves build\web on. The export itself is blocked upstream, see FAQ.
UO_WEB_BROWSER	unset	A browser executable for the web smoke; Chrome or Edge is found otherwise.

Key	Default	Meaning
UO_PYTHON	python	The interpreter every tool runs under.
UO_LOG_LEVEL	INFO	Log level for the Python tools.
UO_COMMON_CONFIG	unset	Path of a central config .bat read after config.bat, for a repo hosting several projects.
UO_PROFILE_PLATFORM	unset	Runtime only: force the per-platform profile table (desktop, mobile, web) on the desktop, for checks. See Mobile UI.
GUO_BRIDGE_MAPS	0,1,2,3,4,5	Which maps the editor's ModernUO bridge assembly serves (ADR-0012).

Like ClassicUO, the client writes settings.json, the per-character profiles and gumps.xml under its working directory, which the host sets before the client namespace is touched (ADR-0006). Scripted runs that need a clean home pass --cache-dir and get their own copy; the real settings are never edited by a probe.