API Reference

Public types grouped by owning plugin. Identifiers are exact; verify against the headers if you extend them.

Contract

Type	Kind	Purpose
`ICrimsonInteractableTarget`	Interface	Implement to be interactable. `GatherInteractionOptions` (C++) / `K2 Gather Interaction Options` (BP), `CustomizeInteractionEventData` (C++ only), `OnInteractableHovered` / `OnInteractableUnhovered`, `NotifyInteractionSuccess`, `NotifyInteractionProgress` (all four BlueprintNativeEvent).
`ICrimsonInteractionInstigator`	Interface	Optional arbitration hook. `ChooseBestInteractionOption(Query, Options)` (BlueprintNativeEvent) picks the winning option.
`FCrimsonInteractionOption`	Struct	`Text`, `SubText`, `InteractionAbilityToGrant` (Method 1), `TargetAbilitySystem` + `TargetInteractionAbilityHandle` (Method 2, runtime-filled), `InteractionWidgetClass`, `InputType`, `InputHoldDuration`, `InteractionActionAbility`, `InteractableTarget` (stamped automatically), `Conditions` / `ConditionSets` (`UCrimsonInteractionCondition` requirements, evaluated by the scan task and re-checked on the server), `bInformational` (a message: no key glyph, never fires, grayed in the menu; set by a failed `ShowInformational` condition or by hand).
`ECrimsonInteractionInputType`	Enum	`Instant`, `Hold` - the only two values.
`FCrimsonInteractionQuery`	Struct	`RequestingAvatar`, `RequestingController`, `OptionalObjectData` (all weak pointers).
`FCrimsonInteractionOptionBuilder`	Helper (C++-only)	`AddInteractionOption` - copies the option and stamps `InteractableTarget` with the gathering scope. Not exposed to Blueprint (the K2 gather path stamps for you).
`FCrimsonInteractionProgressMessage` (CrimsonCore)	Struct	Lives in CrimsonCore with the tag `Message.Interaction.Progress`; standalone, use `UCrimsonInteractionDurationContext::OnProgressChanged`.

Option equality quirk

FCrimsonInteractionOption::operator== compares target, granted/target ability, widget class, and text - it ignores InputType, InputHoldDuration, and InteractionActionAbility. The scan's change-detection therefore does not re-broadcast when only those fields change.

Mechanism (CrimsonInteraction - this plugin)

Type	Kind	Purpose
`UCrimsonAbilityTask_WaitForInteractableTargets`	AbilityTask (abstract)	Base scan task. `InteractableObjectsChanged` delegate; `CurrentOptions` (BP-readable, priority order); `UpdateInteractableOptions` (BlueprintNativeEvent) gathers, evaluates each option's conditions (`Hide` drops it, `ShowInformational` keeps it as a message that skips the ability check), filters the rest by `CanActivateAbility`, change-detects, broadcasts; `SetTraceProfile` / `GetTraceProfileName`.
`UCrimsonAbilityTask_WaitForInteractableTargets_SingleLineTrace`	AbilityTask	Node `Wait For Interactable Targets Single Line Trace` `(Query, TraceChannel, StartLocation, ScanRange=100, ScanRate=0.1, bShowDebug=false)`. Forward multi-trace through the camera; stops at the first interactable hit.
`UCrimsonAbilityTask_WaitForInteractableTargets_TopDownTrace`	AbilityTask	Node `Wait For Interactable Targets Top Down Trace` `(Query, TraceChannel, GroundTraceProfile, TraceDistance=10000, InteractionDistance=200, InteractionRadius=200, ScanRate=0.1, bShowDebug=false)`. Cursor deproject + sphere overlap; hover enter/leave on the focused target.
`UCrimsonAbilityTask_GrantNearbyInteraction`	AbilityTask	Node `Grant Abilities For Nearby Interactors` `(ScanRange, ScanRate, TraceChannel)`. Server-only; grants both `InteractionAbilityToGrant` and `InteractionActionAbility` per nearby option (spec `SourceObject` = avatar, so it replicates); revokes on leave; clears all on destroy.
`UCrimsonInteractionStatics`	BlueprintFunctionLibrary	`TriggerInteractionOption(Option, Instigator, EventTag) -> bool` (back-fill + payload hook + trigger by handle), `GetActorFromInteractableTarget`, `GetInteractableTargetsFromActor`, `AppendInteractableTargetsFromHitResult`. (`GetContextActionsForActor` moved to CrimsonCore's `UCrimsonCoreInteractionStatics`.) C++-only: `AppendInteractableTargetsFromOverlapResults`.
`UCrimsonInteractionDurationContext`	UObject (BlueprintType)	Data object for progress widgets. `Construct(WidgetClass, Text, Duration)`, `UpdateProgress(Progress, Duration)`, `OnProgressChanged` (assignable), `WidgetClass` / `InteractionText` / `CastDuration` (read-only).
`ACrimsonGameplayAbilityTargetActor_Interact`	TargetActor	`AGameplayAbilityTargetActor_Trace` subclass for reticle traces (C++ `PerformTrace` override). Not used by the scan tasks - for bespoke target-actor workflows.
`UCrimsonInteractionSettings`	DeveloperSettings	Project Settings -> Crimson -> Crimson Interaction (`DefaultCrimsonInteraction.ini`). `InteractionTraceChannel` (Visibility), `OverlapProfileName`, `BlockProfileName`, `DefaultScanRange` (500), `DefaultScanRate` (0.1), `TopDownTraceDistance` (10000), `TopDownInteractionRadius` (200), `bShowDebugByDefault` (false). C++: `UCrimsonInteractionSettings::Get()`; not Blueprint-readable.

One ability, one tag

This plugin ships one ability, UCrimsonGameplayAbility_BasicInteract, and registers one gameplay tag, Ability.Interaction.Activate (its default event tag; CrimsonCore uses the same string). Message.Interaction.Progress belongs to CrimsonCore; any other Ability.Interaction.* strings are conventions you define yourself (How-To: Write Your Own Interact Ability step 1).

Prebuilt layer (CrimsonCore - requires all Crimson plugins)

Listed for orientation only - these types are not part of CrimsonInteraction. CrimsonCore is free to download and read, but it only compiles in projects that have every Crimson plugin installed. Everything here has a self-built equivalent in How-To: Write Your Own Interact Ability and How-To: Add Holds, Channels & a Progress Prompt.

Type	Kind	Purpose
`UCrimsonGameplayAbility_Interact`	GameplayAbility (abstract)	Base interact ability: press decision tree, ability-timer holds, instigator hook, target progress, channel launch.
`UCrimsonCoreGameplayAbility_Interact`	GameplayAbility	Ready-made: `ScanStrategy` (TopDown / SingleLineTrace), auto-activation on spawn, input binding via `InputTag.Interact`, prompt presentation via `PromptMode` (WorldIndicator / HudSlot / Both / Custom), world indicators, context-menu input. Seeds tunables from `UCrimsonInteractionSettings`.
`UCrimsonGameplayAbility_InteractionDuration` / `UCrimsonCoreGameplayAbility_InteractionDuration`	GameplayAbility	Channel base + concrete 3s default. `DurationSeconds`, `CalculateProgressStep`, opt-in `MaxDistanceFromTarget` / `bCancelWhenInputReleased`, success event on the target ASC.
`UCrimsonCoreGameplayAbility_InteractionHandler`	GameplayAbility	Default `InteractionAbilityToGrant`: triggered by `Ability.Interaction.Activate`, calls `NotifyInteractionSuccess` on the target.
`ACrimsonInteractableActor`	Actor	Drop-in interactable: Details-panel `InteractionOptions` array (each option carries its own `Conditions`: a key, a level, a tag query; CrimsonCore's `ACrimsonCoreDoor` gates its own options the same way, for keys and a lockpick), `On Interacted` / `On Interaction Progress` / `On Hover Changed` BP events, optional context menu.
`UCrimsonCoreInteractionPromptWidget`	Widget	HUD prompt driven by `Message.Interaction.OptionsChanged` + `Message.Interaction.Progress`; progress ring via its `ActionWidget` material layer.
`FCrimsonInteractionOptionsChangedMessage`	Struct	Channel `Message.Interaction.OptionsChanged` (CrimsonCore tag). `Instigator` + `Options` - drives the prompt without referencing the ability.