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.NET / AvaloniaBeta

Behavior Graph Studio

A standalone editor for Fallout 4's Havok behaviour graphs. Inspect the real object graph, edit fields and graph structure, manage symbols, preview animations, compare files, simulate state-machine logic, validate your project, and save supported changes straight back to .hkx.

What it is

Fallout 4 keeps its animation logic in behaviour files: which clip plays, when it plays, how it blends, what events fire, and how states connect. Behavior Graph Studio reads the Fallout 4 Havok format directly and presents it as a tree, graph, symbol table, project chain, animation inspector, playback view, and comparison workspace. Supported edits use the built-in native save pipeline, with no Havok Content Tools, Java runtime, or game SDK required.

Behavior Graph Studio's playback view rendering Dogmeat's wireframe skeleton
Behavior Graph Studio Bridge home screen
Behavior Graph Studio Assistant drawer

Guide

A full workflow from opening your first file to tracing graph logic, previewing animations, validating changes, comparing the final result, and testing safely in Fallout 4.

Safe editing: supported field and structural edits use the native save pipeline, and saving keeps the previous file as a .bak. If an edit cannot be represented safely, the application refuses the save instead of replacing the source file. Keep your backup until the edited behaviour has been tested in game.
Automation: BGS also includes a bounded external stdio MCP server for inspection and side-effect-free previews. See the MCP integration guide and API reference.
Release scope: Review the full release notes for the month's workspace, authoring, animation, ragdoll, cloth, diagnostics, Assistant, MCP, and save-safety work, including what remains intentionally limited.