unreal-engine-skills

Use when writing Unreal Engine C++ that touches the reflection system or core types: UCLASS, UPROPERTY, UFUNCTION, USTRUCT, UENUM, GENERATEDBODY, TObjectPtr, TWeakObjectPtr, TSharedPtr, FGCObject, TArray, TMap, TSet, TOptional, TVariant, DECLAREDYNAMICMULTICASTDELEGATE, AddDynamic, FName, FString, FText, UGameInstanceSubsystem, UWorldSubsystem, GetDefault, TNotNull. Also use when the user mentions 'UE C++', 'garbage collection', 'CDO', 'smart pointers' or 'specifiers'. For Actor and component lifecycle, see ue-actor-component-architecture; for Build.cs and modules, see ue-module-build-system; for Blueprint-facing functions and latent actions, see ue-blueprint-cpp-interop.

Use when writing or fixing Unreal Engine UI in C++ — UMG user widgets, Slate widgets, Common UI screens, or MVVM view models. Also use when the user mentions 'UUserWidget', 'NativeConstruct', 'BindWidget', 'CreateWidget', 'AddToViewport', 'ESlateVisibility', 'OnClicked', 'UListView', 'widget animation', 'SNew', 'SLATEBEGINARGS', 'SCompoundWidget', 'UCommonActivatableWidget', 'activatable widget stack', 'UCommonButtonBase', 'gamepad focus', 'FUIInputConfig', 'UMVVMViewModelBase', 'FieldNotify', or 'WidgetComponent'. For input modes and Enhanced Input, see ue-input-system; for Slate in editor tooling, see ue-editor-tools.

Use when extending the Unreal Editor from C++ with detail customizations, editor utility widgets, menus, editor modes, asset definitions or editor subsystems. Also use when the user mentions 'IDetailCustomization', 'IPropertyTypeCustomization', 'CustomizeDetails', 'RegisterCustomClassLayout', 'IDetailLayoutBuilder', 'AddCustomRow', 'IPropertyHandle', 'UToolMenus', 'ExtendMenu', 'FToolMenuEntry', 'UEditorUtilityWidget', 'Blutility', 'UAssetActionUtility', 'UEditorSubsystem', 'UEdMode', 'UAssetDefinition', 'UFactory', 'FScopedTransaction', or 'editor module'. For Slate fundamentals, see ue-ui-umg-slate; for Build.cs wiring, see ue-module-build-system.

Use when creating, refreshing or repairing .agents/ue-project-context.md, the project document every other UE skill reads first. Also use when the user says 'project context', 'set up context', 'UE context', 'scan my project', 'onboard the agent to my project', 'update project context', 'configure project', 'what engine version is this project on', 'which plugins do we have enabled', or complains that UE advice keeps coming out generic. For Build.cs and Target.cs mechanics, see ue-module-build-system; for naming and API-macro conventions, see ue-cpp-foundations; for GAS specifics, see ue-gameplay-abilities.

Use when writing or running Unreal Engine tests, adding logging, or profiling a build. Also use when the user mentions 'UELOG', 'log category', 'DEFINELOGCATEGORY', 'UELOGFMT', 'verbosity', 'check', 'ensure', 'ensureMsgf', 'verify', 'IMPLEMENTSIMPLEAUTOMATIONTEST', 'automation test', 'TESTCLASS', 'CQTest', 'AFunctionalTest', 'latent command', 'Unreal Insights', 'TRACECPUPROFILEREVENTSCOPE', 'TRACEBOOKMARK', 'stat unit', 'SCOPECYCLECOUNTER', 'memreport', 'DrawDebugLine', 'UEVLOG', 'gameplay debugger', 'ShowDebug', 'console command', 'CVar', or 'why is my frame time bad'. For module and target wiring, see ue-module-build-system; for editor tooling, see ue-editor-tools.

Use when writing or fixing Build.cs, Target.cs, .uproject or .uplugin files, creating a module or plugin, or resolving an Unreal build error. Also use when the user mentions 'unresolved external symbol', 'LNK2019', 'cannot open include file', 'C1083', 'MODULENAMEAPI', 'PublicDependencyModuleNames', 'IWYU', 'PCHUsage', 'IMPLEMENTMODULE', 'IMPLEMENTPRIMARYGAMEMODULE', 'LoadingPhase', 'circular dependency', 'Missing precompiled manifest', 'EngineAssociation', 'IncludeOrderVersion', 'Live Coding'. For UCLASS/UPROPERTY rules see ue-cpp-foundations; for editor modules see ue-editor-tools; for Game Feature plugins see ue-game-features.

Use when writing C++ for materials or rendering — dynamic material instances, material parameter collections, render targets, scene capture, post process, decals, Nanite, Lumen, MegaLights, Substrate. Also use when the user mentions 'MID', 'CreateDynamicMaterialInstance', 'SetScalarParameterValue', 'UMaterialInstanceDynamic', 'material parameter collection', 'UTextureRenderTarget2D', 'DrawMaterialToRenderTarget', 'scene capture', 'post process volume', 'FPostProcessSettings', 'bOverride', 'blendable', 'decal', 'custom depth stencil', 'Nanite', 'Lumen' or 'global shader'. For Niagara materials, see ue-niagara-effects; for UMG materials, see ue-ui-umg-slate.

Use when driving Niagara VFX from C++: spawning a system, overriding User parameters, binding data interfaces, sending gameplay data through Niagara Data Channels, pooling components or handling OnSystemFinished. Also use when the user mentions 'Niagara', 'particle system', 'VFX', 'UNiagaraComponent', 'UNiagaraFunctionLibrary', 'SpawnSystemAtLocation', 'SpawnSystemAttached', 'SetVariableFloat', 'User. parameter', 'data interface', 'ENCPoolMethod', 'sim cache', 'lightweight emitter', 'muzzle flash' or 'impact effect'. For particle materials and dynamic material instances, see ue-materials-rendering; for audio-reactive effects, see ue-audio-system.

Use when writing or fixing Unreal Engine gameplay framework classes — GameMode, GameState, PlayerController, PlayerState, Pawn, Character, HUD, GameInstance — and the flows they own: player join, pawn spawning, match state, travel and non-GAS damage. Also use when the user mentions 'AGameModeBase', 'PostLogin', 'OnPostLogin', 'RestartPlayer', 'SpawnDefaultPawnFor', 'ChoosePlayerStart', 'match state', 'PossessedBy', 'seamless travel', 'ServerTravel', 'DrawHUD', 'TakeDamage', 'ApplyRadialDamage' or 'create session'. For replication, see ue-networking-replication; for CharacterMovementComponent, see ue-character-movement; for cameras, see ue-gameplay-cameras; for input, see ue-input-system.

Use when writing or debugging AActor and UActorComponent C++: constructor vs BeginPlay, PostInitializeComponents, EndPlay cleanup, SpawnActor/SpawnActorDeferred/FinishSpawning, CreateDefaultSubobject, NewObject + RegisterComponent, SetupAttachment/AttachToComponent, tick groups, UChildActorComponent, UINTERFACE, actor pooling. Also use when the user mentions 'BeginPlay', 'Tick', 'SpawnActor', 'CreateDefaultSubobject', 'attach a component', 'root component', 'lifecycle', 'PrimaryActorTick', 'FAttachmentTransformRules'. For collision and overlaps, see ue-physics-collision; for GameMode/Pawn/Controller, see ue-gameplay-framework; for replicated actors, see ue-networking-replication.

Use when writing or debugging Unreal Engine animation C++: AnimInstance subclasses, thread-safe update, FAnimInstanceProxy, montage playback and delegates, anim notifies, animation curves, blend spaces, anim state machines, linked anim layers, root motion. Also use when the user mentions 'UAnimInstance', 'NativeUpdateAnimation', 'NativeThreadSafeUpdateAnimation', 'MontagePlay', 'OnMontageEnded', 'UAnimNotify', 'UAnimNotifyState', 'branching point', 'GetCurveValue', 'blend space', 'AnimGraph', 'LinkAnimClassLayers', 'motion matching', 'motion warping', 'root motion'. For movement and RootMotionSource, see ue-character-movement; for montage-driven abilities, see ue-gameplay-abilities.

Use when wiring player input in Unreal C++ with Enhanced Input — input actions, mapping contexts, triggers, modifiers, binding handlers and runtime key rebinding. Also use when the user mentions 'Enhanced Input', 'UInputAction', 'UInputMappingContext', 'AddMappingContext', 'BindAction', 'SetupPlayerInputComponent', 'ETriggerEvent', 'input trigger', 'input modifier', 'SwizzleAxis', 'dead zone', 'WASD', 'gamepad', 'key rebinding', 'UEnhancedInputUserSettings' or 'input mapping priority'. For UI input modes and CommonUI routing, see ue-ui-umg-slate; for PlayerController/Pawn possession, see ue-gameplay-framework.

Use when modelling designer-authored game data in C++ and loading it: data assets, data tables, curve tables, soft references and asset streaming. Also use when the user mentions 'UDataAsset', 'UPrimaryDataAsset', 'UDataTable', 'FTableRowBase', 'FindRow', 'FDataTableRowHandle', 'TSoftObjectPtr', 'TSoftClassPtr', 'FSoftObjectPath', 'UAssetManager', 'LoadPrimaryAsset', 'FStreamableManager', 'RequestAsyncLoad', 'asset bundles', 'PrimaryAssetTypesToScan', 'IAssetRegistry', 'CSV import', or 'hard vs soft reference'. For save games, see ue-serialization-savegames; for UPROPERTY basics, see ue-cpp-foundations; for level streaming, see ue-world-level-streaming.

Use when writing or debugging UCharacterMovementComponent code: custom movement modes, floor detection, jumping, crouching, root motion, moving platforms, or client-side movement prediction. Also use when the user mentions 'CharacterMovementComponent', 'CMC', 'PhysCustom', 'PhysWalking', 'MOVECustom', 'FSavedMoveCharacter', 'GetCompressedFlags', 'FCharacterNetworkMoveData', 'MovementBase', 'LaunchCharacter', 'WalkableFloorAngle', 'SetGravityDirection', 'NavWalking', or 'FRootMotionSource'. For the Mover plugin, see ue-mover; for replication mechanics, see ue-networking-replication.

Use when generating world content or geometry procedurally in Unreal Engine: PCG graphs, custom PCG nodes in C++, runtime mesh building, instancing and seeded noise. Also use when the user mentions 'PCG', 'UPCGComponent', 'UPCGSettings', 'IPCGElement', 'UPCGBasePointData', 'surface sampler', 'static mesh spawner', 'runtime generation', 'CreateMeshSection', 'UProceduralMeshComponent', 'UDynamicMeshComponent', 'Geometry Script', 'AddInstance', 'HISM', 'spline mesh', 'PerlinNoise', 'FRandomStream', 'scatter foliage' or 'marching cubes'. For collision on generated geometry, see ue-physics-collision; for instance materials, see ue-materials-rendering; for background work, see ue-async-threading.

Use when setting up collision channels and profiles, running line/sweep/overlap queries, wiring hit and overlap events, or simulating rigid bodies in Unreal Engine C++. Also use when the user mentions 'collision channel', 'collision profile', 'LineTraceSingleByChannel', 'SweepSingleByChannel', 'OverlapMultiByObjectType', 'FHitResult', 'FCollisionQueryParams', 'FCollisionShape', 'OnComponentHit', 'OnComponentBeginOverlap', 'SetCollisionProfileName', 'SetSimulatePhysics', 'AddRadialImpulse', 'ragdoll', 'Chaos solver', 'ECCGameTraceChannel1', or 'my overlap never fires'. For component attachment, see ue-actor-component-architecture; for capsule floor checks, see ue-character-movement.

Use when implementing or debugging the Gameplay Ability System in C++ — abilities, effects, attributes, cues and the AbilitySystemComponent. Also use when the user mentions 'GAS', 'UGameplayAbility', 'ActivateAbility', 'CommitAbility', 'UGameplayEffect', 'UAttributeSet', 'FGameplayAttributeData', 'AbilitySystemComponent', 'InitAbilityActorInfo', 'GiveAbility', 'TryActivateAbility', 'ability task', 'GameplayCue', 'cooldown', 'cost', 'buff', 'debuff', 'damage execution' or 'ASC on PlayerState'. For montage playback, see ue-animation-system; for replication modes and prediction, see ue-networking-replication.

Use when writing multiplayer C++: replicating a property, choosing an RPC type, tuning relevancy or dormancy, registering replicated subobjects, or turning on push model or Iris. Also use when the user mentions 'replicate a variable', 'OnRep', 'DOREPLIFETIME', 'GetLifetimeReplicatedProps', 'Server RPC', 'NetMulticast', 'WithValidation', 'CONDOwnerOnly', 'HasAuthority', 'ENetRole', 'FFastArraySerializer', 'MARKPROPERTYDIRTYFROMNAME', 'net dormancy', 'replication graph', 'dedicated server' or 'listen server'. For GAS prediction and attribute replication, see ue-gameplay-abilities; for movement replication and CMC prediction, see ue-character-movement.

Use when writing Unreal Engine C++ AI — AI controllers, behavior tree nodes, blackboards, AI perception, navmesh pathfinding, EQS queries or Smart Objects. Also use when the user mentions 'AAIController', 'UBTTaskNode', 'ExecuteTask', 'FinishLatentTask', 'UBlackboardComponent', 'FBlackboardKeySelector', 'UAIPerceptionComponent', 'FAIStimulus', 'UAISenseConfigSight', 'MoveTo', 'UNavigationSystemV1', 'ProjectPointToNavigation', 'UNavArea', 'ANavLinkProxy', 'UEnvQueryManager', 'FEnvQueryRequest', 'EQS', 'navmesh', 'USmartObjectSubsystem' or 'ZoneGraph'. For State Tree authoring, see ue-state-trees; for Mass crowds, see ue-mass-entity; for the movement component that executes paths, see ue-character-movement.

Use when streaming levels in and out, setting up World Partition, or moving between maps. Also use when the user mentions 'level streaming', 'World Partition', 'data layer', 'UDataLayerManager', 'SetDataLayerRuntimeState', 'LoadStreamLevel', 'UnloadStreamLevel', 'ULevelStreamingDynamic', 'LoadLevelInstance', 'ALevelInstance', 'streaming source', 'streaming volume', 'HLOD', 'OpenLevel', 'ServerTravel', 'seamless travel', 'sub-level', 'open world', or 'UWorldSubsystem'. For replication and net relevancy, see ue-networking-replication; for GameMode travel callbacks, see ue-gameplay-framework; for saving world state to disk, see ue-serialization-savegames.

Use when playing Level Sequences from C++, building cutscenes or in-game camera moments, binding actors to sequence tracks at runtime, wiring Sequencer event tracks, or rendering with Movie Render Graph. Also use when the user mentions 'Sequencer', 'LevelSequence', 'ALevelSequenceActor', 'ULevelSequencePlayer', 'CreateLevelSequencePlayer', 'cutscene', 'camera cut', 'event track', 'ULevelSequenceDirector', 'SetBindingByTag', 'spawnable', 'possessable', 'CineCamera', 'Movie Render Queue', or 'MRQ'. For animation tracks, see ue-animation-system; for gameplay cameras and shakes, see ue-gameplay-cameras; for sequence audio, see ue-audio-system.

Use when implementing save/load, player progress persistence, slot management, or binary serialization in Unreal Engine C++. Also use when the user mentions 'save game', 'USaveGame', 'SaveGameToSlot', 'AsyncSaveGameToSlot', 'LoadGameFromSlot', 'DoesSaveGameExist', 'DeleteGameInSlot', 'ULocalPlayerSaveGame', 'UPROPERTY(SaveGame)', 'FArchive', 'FMemoryWriter', 'FCustomVersion', 'save versioning', 'migrate old saves', 'save file corrupted', 'UDeveloperSettings', or 'GConfig'. For asset references, see ue-data-assets-tables; for work off the game thread, see ue-async-threading; for streamed level state, see ue-world-level-streaming.

Use when playing, mixing or debugging sound in Unreal Engine — one-shot SFX, looping ambience, music, dialogue or procedural audio. Also use when the user mentions 'UAudioComponent', 'PlaySoundAtLocation', 'SpawnSoundAttached', 'SoundCue', 'MetaSound', 'UMetaSoundSource', 'SetFloatParameter', 'sound attenuation', 'spatialization', 'occlusion', 'sound concurrency', 'submix', 'audio bus', 'sound mix', 'SetSubmixOutputVolume', 'reverb', 'Quartz', 'audio modulation' or 'subtitles'. For VFX timing, see ue-niagara-effects; for anim-notify sounds, see ue-animation-system; for component lifetime and attachment, see ue-actor-component-architecture.

Use when writing or debugging State Tree logic in Unreal Engine C++ — tasks, conditions, evaluators, considerations, schemas, transitions, events or Mass behaviours. Also use when the user mentions 'StateTree', 'state tree', 'FStateTreeTaskBase', 'FStateTreeExecutionContext', 'GetInstanceDataType', 'FInstanceDataType', 'UStateTreeComponent', 'UStateTreeAIComponent', 'FStateTreeReference', 'SendStateTreeEvent', 'EStateTreeRunStatus', 'StateTree schema', 'utility selection', 'scheduled tick', 'FinishTask', or 'Mass StateTree'. For behaviour trees, perception and navigation, see ue-ai-navigation; for Mass processors and fragments, see ue-mass-entity; for USTRUCT basics, see ue-cpp-foundations.

Use when offloading work off the game thread, dispatching results back to it, running data-parallel loops, or scheduling timers and tickers in UE C++. Also use when the user mentions 'UE::Tasks::Launch', 'FPipe', 'FTaskEvent', 'AsyncTask', 'Async()', 'TFuture', 'TPromise', 'ParallelFor', 'FRunnable', 'FAsyncTask', 'FCriticalSection', 'FRWLock', 'UE::FMutex', 'TMpscQueue', 'IsInGameThread', 'FTSTicker', 'SetTimer', 'thread safety'. For async asset loading, see ue-data-assets-tables; for smart pointers and GC lifetime, see ue-cpp-foundations.

Use when building, activating or debugging Game Feature plugins and modular gameplay. Also use when the user mentions 'GameFeatureAction', 'UGameFeatureData', 'GameFeaturesSubsystem', 'LoadAndActivateGameFeaturePlugin', 'BuiltInInitialFeatureState', 'ExplicitlyLoaded', '.uplugin', 'GameFrameworkComponentManager', 'AddReceiver', 'AddComponentRequest', 'AddExtensionHandler', 'NAMEGameActorReady', 'init state', 'UPawnComponent', 'ModularGameplay', 'experience system' or 'Lyra-style modular architecture'. For plugin modules and Build.cs wiring, see ue-module-build-system; for component fundamentals, see ue-actor-component-architecture.

Use when writing or debugging Mass Entity ECS code in Unreal Engine C++ — processors, queries, fragments, tags, observers, traits, spawning and large-scale agent simulation. Also use when the user mentions 'MassEntity', 'UMassProcessor', 'FMassEntityQuery', 'ForEachEntityChunk', 'FMassEntityManager', 'FMassFragment', 'FMassTag', 'FTransformFragment', 'UMassObserverProcessor', 'ObservedTypes', 'Defer', 'archetype', 'AMassSpawner', 'entity config asset', 'MassCrowd', 'ISM crowd', 'entity relations', or 'thousands of agents'. For State Tree behavior on entities, see ue-state-trees; for ZoneGraph and Smart Objects, see ue-ai-navigation; for thread-safety rules, see ue-async-threading.