Highly Performant & Scalable Ultima Online Server Emulator https://www.modernuo.com
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Kamron Batman 9d26a44a28
fix: Fixes pathfinding prebake and pathfinding multi-fallthrough. (#2478)
## Summary

Fixes the pathfinding step-cache (`.swb`) prebake so it bakes **once** and skips when a valid cache already exists, instead of re-baking on every boot. The root cause was the staleness fingerprint hashing mutable in-memory tile data rather than the on-disk files. This PR makes the fingerprint a pure function of the client data files and separates dynamic multis (houses/boats) from the static cache.

> This branch builds on the `ConfigurePrompts` first-boot-prompt unification (commit `5df8d0bd`, also included here) — that commit accounts for the `ServerConfiguration.cs` and `dev-docs/server-lifecycle.md` changes in the diff.

## The bug

With `pathfinding.prebakeMaps` set, the cache re-baked on **every** boot. The `.swb` staleness fingerprint hashed the live `TileData.LandTable`/`ItemTable` flags, which the server patches at runtime (`ItemFixes`, `LOSBlocker`, `PotionKeg`, `CTF`) at nondeterministic lifecycle points (Initialize-phase methods share a priority; static ctors fire lazily). So a fingerprint stamped at runtime (`[PathBake`) never matched the one recomputed during startup `Initialize()`, and the cache rebaked every time.

## Changes

**1. Fingerprint the files, not the in-memory tables** (`fix`)
Hash `tiledata.mul` (cached, computed once) plus the per-map `.mul`/`.uop` files — never the runtime-mutated `TileData` tables. The fingerprint is now lifecycle-stable. Existing `.swb` files rebake once after deploy, then stay stable.

**2. Compute the fingerprint once per boot** (`refactor`)
`Configure()`'s `AutoLoadAtStartup()` already opens and fingerprint-validates a reader for every up-to-date `.swb`. `Initialize()` now skips baking any map that already has an open reader (`StepCache.HasLazyReader`) instead of recomputing the fingerprint a second time.

**3. Bake static-only; route multis to the live path** (`refactor`)
Multis (houses/boats) are dynamic, so they're no longer baked into the static chunk cache — they were tagged with `BuiltMultisVersion`, a non-persisted session counter, which made persisting them unsafe (false matches / wasted re-bakes).
- Chunks bake land + `statics.mul` only.
- At query time, any cell whose sector (or its 1-cell halo) contains a multi routes to `Fallthrough_Multi` → the existing live, multi-aware `CheckMovement` path. The halo prevents a cell proposing a walkable edge into a neighbouring wall; interior (multi-free) cells pay one sector lookup.
- Adds `Sector.HasMultis` (one engine accessor); `.swb` format → v9 (rejects old multi-baked files); new `Fallthrough_Multi` telemetry.
- Behaviour-preserving: multis use the same live path the engine used before the cache existed.

**4. Comment polish** (`style`) — no behaviour change.

## Testing

All green: **92** pathfinding (incl. a new fingerprint-stability test and a multi-halo fallthrough test), **423** UOContent, **708** Server.

## Follow-ups (not in this PR)

- **Background bake worker** — make `[PathBake` and the boot prebake non-blocking (game thread serves tile reads to an off-thread worker).
- **Per-multi MCL cache** — cache walkability in each multi's own frame (keyed by multiID, movement-invariant) so houses/boats get a fast path instead of the live fallback.
- **House-pathfinding equivalence tests** — the one area not yet covered by a dedicated automated test; multi pathing is currently correct by delegation to the live path.
2026-06-08 11:59:24 -07:00
.config feat: Adds Build Tool for Publishing/Setup (#2392) 2026-03-28 21:21:50 -07:00
.github chore: Change signing policy slug to 'release-signing' (#2466) 2026-06-06 15:00:06 -07:00
dev-docs fix: Fixes pathfinding prebake and pathfinding multi-fallthrough. (#2478) 2026-06-08 11:59:24 -07:00
Distribution/Data feat: Adds rope teleporter for New Haven Mines (#2439) 2026-05-03 17:23:31 -07:00
Projects fix: Fixes pathfinding prebake and pathfinding multi-fallthrough. (#2478) 2026-06-08 11:59:24 -07:00
.cursorrules chore: Adds AI instructions and SKILLs for ModernUO codebase (#2347) 2026-03-01 11:42:19 -08:00
.editorconfig chore(docs): Adds UnmanagedDataReader & BinaryFileReader documentation (#1968) 2024-10-01 17:07:51 -07:00
.gitattributes fix: Adds migration checks to CICD, updates dependencies, adds Fedora 37, alpine 3.17 support (#1309) 2022-12-22 12:12:47 -08:00
.gitignore feat: Adds Build Tool for Publishing/Setup (#2392) 2026-03-28 21:21:50 -07:00
AGENTS.md chore: Adds AI instructions and SKILLs for ModernUO codebase (#2347) 2026-03-01 11:42:19 -08:00
azure-pipelines.yml chore: Cleans workflows for NodeJS 24 (#2394) 2026-03-28 21:55:29 -07:00
CLAUDE.md feat(pathfinding): first-boot prompt to pre-bake the .swb map cache (#2475) 2026-06-07 16:30:33 -07:00
CODE_OF_CONDUCT.md Create CODE_OF_CONDUCT.md 2020-05-05 08:51:39 -07:00
CONTRIBUTING.md chore(license): Removes CLA requirement. All contributors moving forward will retain copyright. (#2038) 2024-12-31 02:52:58 -08:00
Directory.Build.props fix: Fixes publishing with build tool (#2398) 2026-04-04 00:35:39 -07:00
FAQ.md docs: Updates FAQ for time zone issues. (#1368) 2023-03-10 00:18:36 -08:00
GEMINI.md chore: Adds AI instructions and SKILLs for ModernUO codebase (#2347) 2026-03-01 11:42:19 -08:00
global.json feat: Adds Build Tool for Publishing/Setup (#2392) 2026-03-28 21:21:50 -07:00
LICENSE Fixes more line ending issues (#267) 2020-09-27 13:54:56 -07:00
ModernUO.slnx feat: Adds Build Tool for Publishing/Setup (#2392) 2026-03-28 21:21:50 -07:00
publish.cmd feat: Adds Build Tool for Publishing/Setup (#2392) 2026-03-28 21:21:50 -07:00
publish.ps1 fix: Adds stamp check for build tool versioning (#2400) 2026-04-06 16:18:02 -06:00
publish.sh fix: Adds stamp check for build tool versioning (#2400) 2026-04-06 16:18:02 -06:00
README.md chore: Update README with Code Signing Policy (#2467) 2026-06-06 15:32:01 -07:00
rider-settings.zip Cleanup/Housekeeping (#242) 2020-09-12 15:31:21 -07:00
Rules.ruleset chore(docs): Adds UnmanagedDataReader & BinaryFileReader documentation (#1968) 2024-10-01 17:07:51 -07:00
SPONSORS.md chore: Updates readme files (#2247) 2025-07-27 11:04:32 -07:00
stylecop.json Updates formatting rules (#199) 2020-08-25 18:00:51 -07:00
THIRD-PARTY-NOTICES docs: Adds RunUO-Encryption notice attribution to DarkStorm (#2369) 2026-03-12 23:35:47 -07:00
version.json feat: Adds Build Tool for Publishing/Setup (#2392) 2026-03-28 21:21:50 -07:00

ModernUO - Ultima Online Server Emulator for the modern era!

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Ultima Online Server Emulator for the modern era!

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Requirements

Supported Operating Systems

Windows 10/11/2012/2016/2019/2022/2025 MacOS 14+ Debian 12+ Ubuntu 22+ LTS
Alpine 3.22+ Fedora 42+ RedHat 9+ CentOS Stream 9+ openSUSE 15.6+ SUSE Enterprise 15 SP6 Linux Mint 21+ Arch

Required Frameworks

All Operating Systems

.NET

Windows

VC++ Redistributable v14

Development

git .NET

Supported IDEs

Jetbrains Rider 2025.3+ space VSCode space Visual Studio 2026

Getting Started

  • Install prerequisite requirements
  • Clone this repository (or download the latest):
    • git clone https://github.com/modernuo/ModernUO.git
  • Open ModernUO.sln to start developing

Building/Publishing

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 Distribution directory
  • Show deployment instructions for cross-compiled builds

Command Line

./publish.cmd [release|debug] [os] [arch]

Linux Prerequisites

Fedora, CentOS, RHEL, etc

dnf upgrade --refresh -y
# CentOS does not come with EPEL enabled
dnf install -y epel-release epel-next-release
dnf install -y findutils libicu libdeflate-devel zstd libargon2-devel liburing-devel

Ubuntu, Debian, etc

apt-get update -y
apt-get install -y libicu-dev libdeflate-dev zstd libargon2-dev liburing-dev

OSX Requirements

brew install icu4c libdeflate zstd argon2

Running the Server

  • Follow the publish instructions
  • The Distribution directory is portable — copy it to your production server for deployment
  • Run ModernUO.exe or dotnet ModernUO.dll from the Distribution directory
  • On first run, the server will prompt you to configure game data file locations

Troubleshooting / FAQ

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Collaborators

Kamron Batman Mark1145

Thanks

  • RunUO Team & Community
  • Voxpire, the ServUO Team & Community
  • Karasho, Jaedan and the ClassicUO Community



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Teams & Roles

Approvers & Committers: Development Team