VTB Assistant

The VTB Assistant is a skill/plugin for Claude and ChatGPT that finds Virtual Test Bed reactor models, explains VTB documentation, and generates or modifies VTB simulation input files. It works entirely from a bundled, curated snapshot of this repository searched by keyword at runtime.

Getting the Assistant

Every merge of devel into main rebuilds the Assistant's knowledge from the VTB repository's current state and republishes it as the latest release, which always has two ready-to-use zips:

Installing the Assistant

For claude.ai or ChatGPT

  1. Download vtb-docs-skill.zip above.

  2. On claude.ai, go to Customize > Skills > Add > Upload skill and upload the zip as-is. On ChatGPT, go to Plugins > Skills > "+" > Upload from your computer.

  3. Start a conversation and ask it a VTB question (see Example Prompts below). Mentioning the VTB is usually enough for it to trigger automatically; to invoke it explicitly, type /vtb-docs on claude.ai or @vtb-docs in ChatGPT.

For Claude Code

  1. Download vtb-assistant-plugin.zip above.

  2. Extract it to ~/.claude/skills/vtb-assistant/ to load it in every session, or to <your-project>/.claude/skills/vtb-assistant/ to load it only for one project (the project's workspace needs to be trusted first). Claude Code auto-loads anything dropped into .claude/skills/* as a "skills-directory plugin," with no build step and no marketplace.

  3. Alternatively, run claude --plugin-dir path/to/vtb-assistant-plugin.zip to load it for a single session without extracting it anywhere permanent.

Example Prompts

  • Finding a model: "What VTB models use Griffin?"

  • Explaining documentation: "Explain the MSRE SAM model."

  • Generating or modifying an input file: "Generate a BISON input file based on the closest VTB example for a TRISO fuel pellet."

warningwarning:Read before generating or modifying an input file

  • Any generated or modified input needs independent engineering review before use in safety analysis, design decisions, or licensing work. The Assistant grounds inputs in real VTB examples but never runs or validates them against the actual application.

  • Generating or modifying an input file is only supported for BISON, Griffin, SAM, Pronghorn, Grizzly, MASTODON, RELAP-7, Sockeye, Cardinal, and BlueCrab. Cardinal and BlueCrab are coupling-only: there is no standalone (non-[MultiApps]) example of either in the VTB.

  • Not supported: NekRS-only models (parts of msr/msre and pbfhr/mark1/reflector), and inventing a new MultiApps/Transfers coupling that isn't already demonstrated in a bundled input.

Content Freshness

The Assistant's knowledge is a static snapshot of this whole repository, models and documentation included, pinned to the commit it was built from (see the bundled ATTRIBUTION.md for the exact commit and retrieval date). It is not a live view of devel: it is regenerated whenever devel is merged into main, so it can lag content on devel by however long that merge takes, but it stays current with everything published on main.

For Developers

The Assistant lives inside this repository at vtb_assistant/ and ships and evolves alongside the models it documents. To build it yourself:


git clone [email protected]:idaholab/virtual_test_bed.git
cd virtual_test_bed/vtb_assistant
uv sync --all-groups
uv run --group harvest python build/harvest.py
uv run --group harvest python build/build_reference_pack.py
./build/package_skill.sh    # zips skills/vtb-docs/ for claude.ai / ChatGPT
./build/package_plugin.sh   # zips the full plugin for Claude Code

See vtb_assistant/README.md and vtb_assistant/CLAUDE.md in the repository for the full development workflow, testing, and packaging details. Those files are the maintained source of truth and are not duplicated here.

Connecting to a Coding Agent

Today the Assistant targets Claude Code, claude.ai, and ChatGPT only. In Claude Code, load a local checkout for development with:


claude --plugin-dir vtb_assistant/

There is deliberately no MCP server, hosted backend, or public Claude Code marketplace listing.