Fighting Game · Guides & deep dives

Mod Scripting Integration

Manifest script entries may use Lua5.4 with .lua entrypoints or WASI0.2 with .wasm entrypoints.

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This document covers TODOS.phase-72.72.14.1.5: Lua/WASI script runtime binding for .mayamod packages, script access to the curated mod API, and development hot reload.

Runtime Surface#

  • module: V2Modding
  • policy: FV2ModScriptRuntimePolicy
  • script binding: FV2ModScriptRuntimeBinding
  • invocation: FV2ModScriptInvocation
  • hot reload request: FV2ModScriptHotReloadRequest
  • result: FV2ModScriptResult
  • helper functions: BuildDefaultModScriptRuntimePolicy, BuildModScriptBindingFromManifest, BuildModScriptInvocation, EvaluateModScriptBinding, ExecuteModScriptInvocation, and EvaluateModScriptHotReload
  • automation: V2/ue/Source/V2Tests/Private/Modding/ModLoadingSystem.spec.cpp
  • contract: V2/ue/Content/V2/Modding/ModScriptingIntegration_V2_Contract.json

Supported Runtimes#

Manifest script entries may use Lua5.4 with .lua entrypoints or WASI0.2 with .wasm entrypoints. Entrypoints must remain under scripts/, script integrity hashes must be present, and runtime resource limits must fit within the default policy caps of 64 MiB and 100 ms.

Mod API Access#

BuildModScriptBindingFromManifest converts manifest script permissions into granted EV2ModApiCapability entries. ExecuteModScriptInvocation only routes script-requested API calls when the capability was granted by the script manifest and is still allowed by the current FV2ModApiPolicy. Each accepted script API call is evaluated through ExecuteModApiRequest, preserving sandbox, network, ranked-safety, event namespace, UI-root, and cosmetic-only world mutation checks.

Hot Reload#

Development hot reload is enabled by FV2ModScriptRuntimePolicy and requires a hot-reloadable binding, a development session, a 64-character replacement script hash, and a strictly increasing script revision. Optional replacement entrypoints must still stay under scripts/ and match the existing runtime extension.

Verification#

bash
python3 V2/ue/Tools/check-v2-mod-scripting-integration.py
python3 V2/ue/Tools/check-v2-mod-api-surface.py
python3 V2/ue/Tools/check-v2-mod-sandboxing.py
python3 V2/ue/Tools/check-v2-mod-loading-system.py
python3 V2/ue/Tools/check-v2-ci-workflow.py
python3 V2/tools/validate-v2-docs.py
python3 -m py_compile V2/ue/Tools/check-v2-mod-scripting-integration.py V2/ue/Tools/check-v2-mod-api-surface.py V2/ue/Tools/check-v2-mod-sandboxing.py V2/ue/Tools/check-v2-mod-loading-system.py V2/ue/Tools/check-v2-ci-workflow.py
python3 -m json.tool V2/ue/Content/V2/Modding/ModScriptingIntegration_V2_Contract.json