vellum-ai/vellum-assistant · assistant/src/config/bundled-skills/app-builder/SKILL.md

app-builder skillA

app-builder is agent-read markdown (skill) from vellum-ai/vellum-assistant: Build and edit small, personal visual tools and artifacts — dashboards, trackers, calculators, data visualizations, charts, simple landing pages, and slide decks the user wants for THEMSELVES. This is the right skill whenever the user asks to "visualize this," "make a chart," or "build an artifact" for their own use, or to edit an app they already built here. Do NOT reach for a ui_show dynamic_page to fake an artifact — build a real persistent app here. A one-off diagram, chart, or explainer tha.

Indexed from public GitHub and served as immutable, content-addressed versions. Install it pinned to an exact SHA-256 with the mdr CLI, and every file is verified against the hash recorded here before it reaches your agent. The deterministic audit below grades the latest version, and the same file always earns the same grade.

How to install

Latest version
mdr add vellum-ai/vellum-assistant/app-builder@git:20260910.689abdd
Exact content
mdr add vellum-ai/vellum-assistant/app-builder@sha256:250636cb68201921

Pin to a label to follow the author's releases, or to a sha256 to freeze the exact bytes forever. Either way the resolved hash is written to mdr.lock, and mdr install reproduces it on any machine.

Badge

mdr badge

[![mdr](https://markdownregistry.com/badge/art_mcrfrwayhm2qzg6u.svg)](https://markdownregistry.com/a/art_mcrfrwayhm2qzg6u)

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Versions

versioncommittedcommitsizeaudit
git:20260910.689abdd latest2026-09-10 689abdd 28,008 BA view · diff
git:20260806.13654212026-08-06 1365421 26,360 BA view · diff
git:20260731.5daeba92026-07-31 5daeba9 26,356 BA view · diff
git:20260728.52ad6332026-07-28 52ad633 26,098 BA view · diff
git:20260716.10b95db2026-07-16 10b95db 25,908 BA view · diff
git:20260716.57b6a662026-07-16 57b6a66 25,760 BA view

Audit of the latest version

A  17 of 17 checks passed. Deterministic, no model, same answer every run.
  • pass: Frontmatter block present
  • pass: Frontmatter declares a name
  • pass: Frontmatter declares a description
  • pass: Size between 200 bytes and 200 KB (28008 bytes)
  • pass: No zero-width or bidi control characters
  • pass: No instruction hidden inside an HTML comment
  • pass: No link to an exfiltration or paste host
  • pass: No credential-shaped string
  • pass: No instruction to send local credentials anywhere
  • pass: No text hidden with inline styles
  • pass: No prompt-injection phrasing
  • pass: No curl or wget piped into a shell
  • pass: No recursive delete of root, home or parent
  • pass: No instruction to read or print local credentials
  • pass: No base64 blob over 200 characters
  • pass: No link to a raw IP address
  • pass: No script tag

Source

GitHub

vellum-ai/vellum-assistant · 1,226 stars · license MIT · pushed 2026-09-10 · branch main

API

GET https://markdownregistry.com/api/v1/artifacts/art_mcrfrwayhm2qzg6u
GET https://markdownregistry.com/api/v1/resolve?ref=vellum-ai/vellum-assistant/app-builder
GET https://markdownregistry.com/api/v1/blob/250636cb682019210f87615f9412ca1278f72b1f1b50953f8f13fe07b5e33880