unreal-packaging — Claude Code skill: what it does, how to install

---
name: unreal-packaging
description: >
  Package and ship an Unreal Engine 5 project: the Platforms menu Package Project flow, build
  configurations (Development vs Shipping), cooking content, packaging settings and the Game
  Default Map, and command-line builds with RunUAT BuildCookRun. Use when packaging a build,
  making a shipping build, cooking content, configuring packaging settings, or when the user
  mentions package Unreal, cook content, shipping build, or BuildCookRun.
---

# Unreal Packaging & Cooking

Turn a UE5 project into a runnable, distributable build: choose the right build configuration,
cook content, set the launch map, and package — from the editor or the command line. Targets
**UE 5.8**.

## When to use

- Use when producing a build (test or release), choosing Development vs Shipping, cooking
  content, configuring Packaging / Maps & Modes settings, or automating builds with
  `RunUAT BuildCookRun` for CI.
- Use when the project has a `*.uproject` and `Config/Default*.ini`, and the goal is a packaged
  player rather than running in-editor.

**When *not* to use:** storefront submission/release process → `steam-publish` / `itch-publish`.
Editor-time gameplay/iteration is not packaging.

## Core workflow

1. **Set the launch map.** Project Settings → **Maps & Modes** → **Game Default Map** is what a
   packaged build loads first. Wrong/empty here is the most common "packaged game is black"
   cause.
2. **Pick the build configuration:** **Development** (default; optimized but keeps logging/
   stats/console for testing) vs **Shipping** (all optimizations, debugging tools stripped — for
   release). `DebugGame`/`Debug` are for debugging engine/game code and aren't for distribution;
   `DebugGame` isn't available for Blueprint-only projects.
3. **Understand cook vs package.** **Cooking** converts assets to the target platform's format.
   **Staging/packaging** copies the compiled executable + cooked content into a standalone,
   distributable folder, with content in container files (`.pak`, plus `.utoc`/`.ucas` when
   **Use Io Store** is on, which is the default). Packaging runs a cook as part of it.
4. **Package from the editor:** the **Platforms** menu → choose the platform (e.g. Windows) →
   set the Binary Configuration → **Package Project** → pick an output folder.
5. **Or build from the command line** with the Unreal Automation Tool (`RunUAT BuildCookRun`)
   for repeatable/CI builds. The **Project Launcher** (Platforms → Project Launcher) saves the
   same build/cook/stage/deploy choices as reusable launch profiles.
6. **Tune Packaging settings** (Project Settings → **Packaging**): which maps/directories to
   cook, full-rebuild, compression, and whether to build all maps.
7. **Validate assets before packaging when UnrealEditor-Cmd is available.** Run
   `UnrealEditor-Cmd <Project>.uproject -run=DataValidation` (`UnrealEditor-Cmd.exe` on
   Windows) and fix every reported validation error before cooking.
8. **Verify** by *running the packaged build*, not just by a successful cook — launch the
   executable and confirm it loads the right map and runs.

## Patterns

### 1. Editor packaging (the menu path)

```text
Platforms (toolbar)
  -> Windows
     -> Binary Configuration -> Development | Shipping
     -> Content Management -> Package Project
  -> choose/confirm the staging output folder
```

### 2. Command-line build with UAT (CI-friendly)

```bash
# Cook + build + stage + pak + archive a Shipping Windows build.
RunUAT BuildCookRun \
  -project="C:/Path/MyGame.uproject" \
  -noP4 -platform=Win64 -clientconfig=Shipping \
  -cook -allmaps -build -stage -pak -archive \
  -archivedirectory="C:/Builds/MyGame"
```

`RunUAT` lives in `Engine/Build/BatchFiles/` (`RunUAT.bat` on Windows, `RunUAT.sh` on
macOS/Linux). Drop `-allmaps` and pass `-map=Map1+Map2` to cook a subset. UE 5.8 adds
experimental Windows on Arm game builds: `-clientarchitecture=arm64` (or `arm64+x64` for both
executables side by side); the editor itself is not supported on Arm64 in 5.8.

### 3. Cook only (no packaging), e.g. to refresh content

```bash
RunUAT BuildCookRun -project="C:/Path/MyGame.uproject" -noP4 \
  -platform=Win64 -clientconfig=Development -cook -skipstage
```

## Pitfalls

- **Packaged build loads a black/empty level** — Game Default Map isn't set (or that map wasn't
  cooked). Set it in Maps & Modes and ensure it's included in the cook.
- **Shipping a Development build** — Development keeps logging/console/stats and is slower; ship
  **Shipping**. Conversely, Shipping strips `UE_LOG`/console, so debugging a Shipping-only issue
  needs Development or `Test`. A Shipping build has no console `quit`, so the game needs its own
  exit option.
- **A referenced map/asset is missing at runtime** — it wasn't cooked. Add it to the Packaging
  settings' maps/directories to cook, or cook all maps.
- **Build fails on the platform** — the platform SDK/toolchain isn't installed or is too old.
  For UE 5.8 on Windows that means Visual Studio 2022 17.14+ (2026 recommended), MSVC 14.38+
  and Windows SDK 10.0.22621.0+; macOS needs Xcode 15.2+. Check the release notes' Platform SDK
  table for other targets. Console packaging also requires a source build of the engine, not
  the Launcher build.
- **`Saved/Cooked/<Platform>` has no `.uasset`/`.uexp` files** — in UE 5.8 Zen Server is the
  cooked output store by default (unless the project turned it off in Packaging settings). The
  folder only holds a small `ue.projectstore` marker and the data lives in the Zen data
  directory. Staging still writes `.pak`/`.utoc`/`.ucas` to the staging folder; ship that
  folder, not `Saved/Cooked`. For team and CI machines Epic recommends
  `LimitProcessLifetime=false` under `[Zen.AutoLaunch]` in `DefaultEngine.ini` so `zenserver`
  is not started and stopped on every step; make sure your build automation tolerates that
  long-running process.
- **Expecting Blueprint Nativization** — it was **removed in UE5**; don't rely on it for
  performance. Profile and move hot logic to C++ (`unreal-cpp-gameplay`) instead.
- **First cook is very slow** — shaders and all assets cook from scratch; subsequent cooks are
  incremental. Don't mistake a slow first cook for a hang.

## References

- Primary docs: "Packaging Your Project"
  (`https://dev.epicgames.com/documentation/en-us/unreal-engine/packaging-your-project`), the
  Build Configurations / `BuildCookRun` references, "Zenserver as Cooked Output Store"
  (`https://dev.epicgames.com/documentation/en-us/unreal-engine/using-zen-storage-server-as-cooked-output-store-for-unreal-engine`)
  and the Platform SDK table in the UE 5.8 release notes
  (`https://dev.epicgames.com/documentation/en-us/unreal-engine/unreal-engine-5-8-release-notes`).

## Related skills

- `steam-publish` / `itch-publish` — distributing the packaged build to a storefront.
- `unreal-cpp-gameplay` — moving hot logic to C++ now that BP nativization is gone.