unreal-gameplay-tags

Define roots by semantic role such as State.*, Ability.*, Event.*, and InputTag.*, assign an owner to each root, and use one canonical tag per concept. Declare stable code-facing tags natively and use config sources for designer-managed sets, adding redirects for any renames.

Hierarchical matching lets a stored child tag satisfy a parent query, so State.Movement.Sprinting matches HasTag(State.Movement). Exact matching requires the literal tag, and matching is directional: a parent never satisfies a more specific child query.

Use FGameplayTagQuery when designers author nested any/all/none logic, when the rule is stored in a Data Asset or Table, or when multiple systems evaluate the same serialized rule. Use direct container operations for simple code-owned checks.

A tag is invalid when it is missing from the registered dictionary in the cooked build or its config/tag source is not included or loaded. Confirm the plugin or module loads as expected and avoid constructing or comparing raw tag strings.

Add a Gameplay Tag redirect from the old name to the new one, then resave and migrate dependent assets and serialized data. Audit text, config, Data Tables, and native constants, and remove the redirect only after all supported content and save versions are migrated.

Keep a private bool when the state is local, performance-critical, and gains nothing from a global vocabulary. Keep an enum for one mutually exclusive closed state machine; use tags when categories are open-ended, hierarchical, or multiple values can coexist.