unreal-pie-control

name	unreal-pie-control
description	Control Play In Editor (PIE) and Simulate In Editor (SIE) sessions via UCP. Use when the user asks to start, stop, pause, resume PIE/SIE, or query PIE state and worlds.

Unreal PIE Control

Control Play In Editor (PIE) and Simulate In Editor (SIE) sessions through UCP's call command.

Prerequisite: The unreal-client-protocol skill must be available and the UE editor must be running with the UCP plugin enabled.

Custom Function Library

UPIEOperationLibrary

CDO Path: /Script/UnrealClientProtocolEditor.Default__PIEOperationLibrary

Function	Params	Returns	Description
StartPIE	(none)	bool	Start a Play In Editor session
StartSimulate	(none)	bool	Start a Simulate In Editor session
StopPIE	(none)	(void)	Stop the current PIE/SIE session
IsInPIE	(none)	bool	Whether a play session is in progress
IsSimulating	(none)	bool	Whether a simulate session is in progress
PausePIE	(none)	bool	Pause all PIE worlds
ResumePIE	(none)	bool	Resume all PIE worlds
GetPIEWorlds	(none)	TArray<UWorld*>	Get all PIE world instances

Examples

Start PIE:

{"object":"/Script/UnrealClientProtocolEditor.Default__PIEOperationLibrary","function":"StartPIE"}

Stop PIE:

{"object":"/Script/UnrealClientProtocolEditor.Default__PIEOperationLibrary","function":"StopPIE"}

Start Simulate:

{"object":"/Script/UnrealClientProtocolEditor.Default__PIEOperationLibrary","function":"StartSimulate"}

Check if PIE is running:

{"object":"/Script/UnrealClientProtocolEditor.Default__PIEOperationLibrary","function":"IsInPIE"}

Pause PIE:

{"object":"/Script/UnrealClientProtocolEditor.Default__PIEOperationLibrary","function":"PausePIE"}

Get PIE worlds:

{"object":"/Script/UnrealClientProtocolEditor.Default__PIEOperationLibrary","function":"GetPIEWorlds"}

Engine Built-in APIs

UEditorLevelLibrary

CDO Path: /Script/EditorScriptingUtilities.Default__EditorLevelLibrary

Function	Description
GetPIEWorlds()	Get worlds from Play-In-Editor sessions (alternative to custom library)

UGameplayStatics (on PIE worlds)

CDO Path: /Script/Engine.Default__GameplayStatics

Once PIE is running, UGameplayStatics functions automatically resolve to the PIE world (UCP's WorldContext auto-injection prefers PIE worlds):

Function	Description
GetPlayerPawn(WorldContextObject, PlayerIndex)	Get the player pawn in PIE
GetPlayerController(WorldContextObject, PlayerIndex)	Get the player controller in PIE
GetAllActorsOfClass(WorldContextObject, ActorClass)	Find actors in the PIE world

Common Patterns

Start PIE, then interact with PIE world

Start a play session, then query actors in the running game (run as separate calls):

{"object":"/Script/UnrealClientProtocolEditor.Default__PIEOperationLibrary","function":"StartPIE"}

After PIE starts, UCP auto-resolves WorldContext to the PIE world:

{"object":"/Script/Engine.Default__GameplayStatics","function":"GetPlayerPawn","params":{"PlayerIndex":0}}

Pause, inspect, resume

{"object":"/Script/UnrealClientProtocolEditor.Default__PIEOperationLibrary","function":"PausePIE"}

Inspect game state while paused, then resume:

{"object":"/Script/UnrealClientProtocolEditor.Default__PIEOperationLibrary","function":"ResumePIE"}

Check state before starting

{"object":"/Script/UnrealClientProtocolEditor.Default__PIEOperationLibrary","function":"IsInPIE"}

If false, start PIE. If true, stop first then restart if needed.

Key Rules

1. Only one PIE/SIE session can be active at a time. Check IsInPIE before starting.
2. StartPIE/StartSimulate are asynchronous — they queue the request, the session starts on the next editor tick. Subsequent calls to functions that depend on PIE being active should be sent as separate requests.
3. StopPIE is also asynchronous — it queues the end request.
4. WorldContext auto-resolution — when PIE is active, UCP automatically uses the PIE world for functions requiring WorldContextObject.