Frequently asked questions

Can I work with the editor closed?

Yes, for supported engine-backed operations. The CLI starts a hidden UnrealEditor-Cmd for the exact project. It still runs Unreal, loads project modules and uses engine serializers. Tools that need Slate, a viewport camera, interactive dialogs or PIE need the appropriate full editor context. See lifecycle and limits.

Resources/Proxy is empty — where is the executable?

ClaudusBridge is distributed as source, so the CLI does not arrive prebuilt: marketplace policy does not allow a plugin to ship executables. Build it once with Tools → Generate Claudus CLI, the ClaudusBridge.BuildCli console command, or the build script in Source/Programs/ClaudusMcpProxy/. It lands in Resources/Proxy/<Platform>/, which is exactly where the editor and every generated client configuration look for it. See Build the CLI.

Building needs a C++ toolchain — on Windows, Visual Studio 2022 Build Tools with the Desktop development with C++ (x64) workload, which any Unreal C++ project already requires. The asset converter needs nothing beyond the .NET SDK that ships inside Unreal.

How do I rebuild the plugin while agents are connected?

Run claudus quiesce --project-path <your .uproject>. It asks the hidden backend to finish its work and exit, and returns only once the binaries are writable, so your build can start immediately afterwards. Any agent can issue it, so a rebuild never waits on another client disconnecting. It refuses to close a visible editor — that may hold unsaved packages — and it is not a lock: keep clients paused so none starts a fresh backend mid-build. See Rebuilding or replacing the plugin.

Do I need Node.js or an AI account for the CLI?

No. The native CLI can discover tools and execute scripted requests without either. Node.js and a provider account are needed for the embedded ClaudusCode agent and ACP conversations. An external assistant has its own model and login requirements.

Which assistants can connect?

Use a client that supports local stdio MCP servers, including the supported configurations for Claude-compatible clients, Cursor, Windsurf, VS Code, Gemini and Codex. Connecting gives the command and argument formats. Version 2.0 does not expose the old HTTP endpoint.

Is it offline?

The CLI, registry, timeline and Unreal bridge run locally. Engine-backed tools can run without model calls. The embedded agent or an external assistant may use internet access for authentication and model inference. Do not confuse a local bridge with an offline AI model.

How many tools are available?

The catalog is generated from engine and project toolsets, so its size changes with the engine and enabled plugins. Use claudus toolsets and claudus describe for the actual names and schemas. Tool-search mode exposes compact discovery tools; seeing only a few top-level MCP tools is expected.

Can it edit every asset or call every C++ function?

No blanket guarantee applies. Reflection works with supported reflected properties/functions and their valid runtime contexts. Specialized graphs need their relevant toolsets. The standalone asset utility has narrower format support than Unreal and may preserve undecoded regions as opaque data. Read reflection and assets.

Are edits automatically saved and undoable?

It depends on the tool. Engine transactions, in-memory changes and disk saves are different operations. Some tools manage their own transactions, some are asynchronous, and external side effects may not be undoable. Inspect the tool schema/result, explicitly save intended packages, then verify after reload when persistence matters.

Can several agents work together?

Yes. Stable identities, persistent sessions, package leases, dirty ownership, job scheduling and a shared timeline help coordinate them. These features do not create parallel game threads or prevent all possible external edits. See multi-agent orchestration.

What happens if a call times out or Unreal restarts?

The client receives an error or cancellation result and the proxy can reconnect. The interrupted operation may already have changed state. Check its object or job before retrying; a timeout is not a rollback.

Why is a hidden Unreal process still running?

A connected MCP client, active tool or shader work can keep it alive. Stop clients and let pending work settle before rebuilding DLLs. The lifecycle guide explains the full sequence.

Is Multi-User required?

No. Multiple MCP agents can share one backend without Concert. Unreal Multi-User is a separate collaboration system for distinct editor participants; it has its own synchronization and persistence rules.

Where are the previous releases documented?

The changelog preserves historical release notes. The legacy documentation covers the older UE 5.7 product. Its transport/setup instructions do not describe version 2.0.