Mass Entity (ECS)

Every live Mass entity manager

Lists every live Mass entity manager the engine debugger knows: world name and type (Editor/PIE/Game), manager debug name, entity and archetype counts, and the selected entity. This is the entry point of the mass group, other commands accept its environment_index to target an exact manager (e.g. PIE server vs client). UE 5.8 only.

cfa list_mass_environments

Archetypes with stats and debug names

Lists archetypes with the same numbers the engine's Mass Debugger window shows: entity count, entities per chunk, chunk count, bytes per entity, allocated and wasted memory, plus every debug name the archetype accumulated. filter matches debug names and composing fragment/tag names. UE 5.8 only.

cfa list_mass_archetypes
cfa list_mass_archetypes --filter Crowd --include-composition true

One archetype in full

One archetype's full composition (fragments, tags, chunk/shared/const-shared and sparse elements), memory stats, debug names, and its first entity handles. Entities are streamed from chunk views, so a million-entity archetype still returns a small answer. UE 5.8 only.

cfa get_mass_archetype --archetype-index 3

Registered Mass element types

The registered Mass element universe straight from the engine's type registries: fragments, tags, chunk, shared and const-shared fragments, each with size and how many archetypes and entities currently use it. UE 5.8 only.

cfa list_mass_fragment_types --kind tag
cfa list_mass_fragment_types --filter Velocity

One Mass element type in detail

One Mass element type: kind, size, reflected properties with types, which archetypes carry it, and which live processors read or write it. UE 5.8 only.

cfa describe_mass_fragment --element MassVelocityFragment

Entity handles, streamed and capped

Entity handles by archetype or by required fragments/tags. Totals are exact, but the list is streamed from chunk views and capped at max_results, so millions of entities never flood the answer. UE 5.8 only.

cfa list_mass_entities --archetype-index 3
cfa list_mass_entities --require-elements MassVelocityFragment --max-results 10

One entity with live fragment values

Everything about one entity: archetype, tags, and the live values of every fragment and shared fragment, read by reflection so any fragment type works. Pass fragment to read just one. UE 5.8 only.

cfa get_mass_entity --entity 42:7
cfa get_mass_entity --entity 42:7 --fragment MassVelocityFragment

Create entities from fragment/tag names

Creates entities from a list of fragment and tag type names, with optional initial values per fragment, no config asset or plugin content needed. The archetype records debug_name so it is recognizable in every listing and in the Mass Debugger window. Not undoable. UE 5.8 only.

cfa create_mass_entities --elements FTestFragment_Int,FTestFragment_Float --count 100 --debug-name CFATest
cfa create_mass_entities --elements FTestFragment_Int --count 5 --values '{"TestFragment_Int":{"Value":7}}'

Destroy entities by handle or archetype

Destroys entities by handle, or a whole archetype through the engine's bulk-destroy path. Never destroys everything by default and reports how many were already gone. Not undoable. UE 5.8 only.

cfa destroy_mass_entities --entities 42:7,43:7
cfa destroy_mass_entities --archetype-index 3

Write live fragment values on one entity

Writes property values into one entity's live fragment memory through reflection, then reads the result back into the response. Refused while Mass is mid-processing, matching the engine's own rule. A running processor may overwrite the value next tick. UE 5.8 only.

cfa set_mass_fragment --entity 42:7 --fragment TestFragment_Int --properties '{"Value":99}'

Add a fragment or tag to an entity

Adds a fragment (with optional initial values) or a tag to a live entity, the kind is detected from the type itself. The entity migrates to a new archetype, whose index is returned. UE 5.8 only.

cfa add_mass_element --entity 42:7 --element FTestFragment_Float --properties '{"Value":1.5}'

Remove a fragment or tag from an entity

Removes a fragment or tag from a live entity, refusing cleanly when the entity does not carry it. UE 5.8 only.

cfa remove_mass_element --entity 42:7 --element FTestFragment_Float

Verdict check on live entities

Returns verdict pass/fail with issues[]: are the entities alive, do their archetypes contain the expected elements, and do live fragment values match the expected ones (numeric comparisons are tolerant). The verification counterpart of create_mass_entities, set_mass_fragment and add_mass_element. UE 5.8 only.

cfa verify_mass_entities --entities 42:7 --expect-elements FTestFragment_Int --expect-values '{"TestFragment_Int":{"Value":99}}'

Live processors and processor classes

Lists live processors from the debugger's own providers (phase-executed, pruned, observers) plus every registered processor class: phase, group, execution flags, query count, active state, and whether each would run in the targeted world. UE 5.8 only.

cfa list_mass_processors
cfa list_mass_processors --source live --phase PrePhysics

One processor with its query requirements

One processor in full: description, execution order (group, before, after), flags, priority, and every query's fragment and tag requirements with access mode and presence, plus how many archetypes and entities it currently matches. UE 5.8 only.

cfa get_mass_processor --processor MassApplyMovementProcessor

The solved per-phase execution order

The solved processor execution order per phase, each node with its sequence index and the processors it waits for. Single-threaded setups report the hosted order instead, flagged single_threaded. Needs a running Mass simulation and explains itself when there is none. UE 5.8 only.

cfa get_mass_processing_graph
cfa get_mass_processing_graph --phase PrePhysics

Ad-hoc archetype/entity query

Runs an ad-hoc query from all/any/none/optional fragment and tag names: matching archetypes with entity counts, optional capped entity handles, and, with explain_archetype_index, the engine's own textual justification for why that archetype does or does not match. UE 5.8 only.

cfa run_mass_query --all MassVelocityFragment
cfa run_mass_query --all MassVelocityFragment --explain-archetype-index 2

Select or clear the debugged entity

Selects, clears, or reports the debugged Mass entity. The selection is shared with the Mass Debugger window and the gameplay debugger's Mass category, so all three stay in sync. UE 5.8 only.

cfa select_mass_entity --entity 42:7
cfa select_mass_entity --clear true

Send a named Mass signal to entities

Sends a named Mass signal to entities, immediately or after a delay, the wake-up mechanism StateTree-driven Mass AI listens on. Only processors subscribed to that exact signal name react. UE 5.8 only.

cfa signal_mass_entities --signal-name NewStateTreeTaskRequired --entities 42:7