uefn-vfx-niagara (MVP experimental, B9)

Source: Claude/docs/mcp/vfx-niagara.md, recipes.json, SKILLS-PROPOSAL.md B9. Read first: skills uefn-mcp-lab-guard and uefn-create-use-remove-one-script.

Rules

• Paths in GUID form: lab root /09e4e8d3-83f9-4ee0-9777-072ed3984380/root_ai_lab.
• The guard is never bypassed; a refusal is reported verbatim. If a recipe fails: report the exact error and STOP.
• NEVER call GetDynamicInputSchema on a non-dynamic input: it crashed the editor. Use GetAvailableDynamicInputs / GetDynamicInputSchemaFromAsset only.
• Must NOT: write to /Niagara/... templates (source only).

Recipes tool-ok or proven (recipes.json, toolset NiagaraToolsets.*)

• Create/remove: NiagaraToolset_System/CreateNiagaraSystem {assetName, assetPath: <lab>/Fx, templateSystem: /Niagara/DefaultAssets/Templates/Systems/MinimalLightweight.MinimalLightweight} (source allowed because result lands in lab); cleanup AssetTools/delete {path:<lab>/Fx}.
• Edit: AddEmitter, RemoveEmitter, AddModule, RemoveModule, AddRenderer, RemoveRenderer, RemoveSetParameterEntry, AddUserVariables, RemoveUserVariables, SetSystemData, SetEmitterData, SetRendererData, SetStackInputData, SetModuleEnabled.
• Read: GetSystemSummary, GetSystemCompileState, GetSystemDependencies, GetStackIssues, GetEmitterSummary, GetEmitterTopology, GetModuleInputValues, GetStackInputData, GetRendererData, GetRendererSchema, NiagaraToolset_Assets/FindNiagaraScripts, GetNiagaraScriptDigest, NiagaraToolset_Info/UEnum_Info.
• Component: NiagaraToolset_Component/GetUserVariables, GetVariable, SetVariable, SetSystem.

Traps

• FindNiagaraScripts needs all of usages, visibilities, supportedUsages, bRecursive, bIncludeDeprecated, folderPath, name.
• AddUserVariables items are FLAT; SetVariable needs {name,type,value}.
• MinimalLightweight yields an empty emitter: use AddEmitter with a real template.
• Delete the NiagaraActor in the same script that spawned it. Payloads 48-56 KB per emitter.

To try (not verified)

• ApplyStackIssueFix: unverified (replies an error but applies; effect not confirmed in recipes.json).
• AddSetParametersModule, AddSetParameterEntry: unverified in recipes.json.
• GetDynamicInputSchema: never call (editor crash).