Vellum Workspace Theme

What it does

When your agent uses it

• Tasks that involve Design tokens
• Tasks that involve Messaging and chat bots

Example prompts

• “/vellum-workspace-theme”

Requirements

• Compatibility (from SKILL.md): Designed for Vellum personal assistants

Workflow steps

5 steps, taken from the first numbered list in SKILL.md.

1. 1Hex colors only — 3- or 6-digit (#f0a, #e8a04c). No alpha channel, no named colors, no CSS functions, no url().
2. 2Only the keys above — unknown top-level keys or token slots reject the file. There is no way to inject arbitrary CSS; that is deliberate.
3. 3Override groups are all-or-none. Tokens that render against each other must be set together, because your overrides layer over a base…
4. 4Contrast floor — text/surface pairs must clear 3:1 (WCAG relative luminance): text against background/surface/surfaceRaised, textMuted…
5. 5A real file, at most 64KB — symlinks and oversized files are rejected.

What it can do on your machine

Read from SKILL.md and the folder at commit 33cc983. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are bash and json).

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

• Compatibility

  Designed for Vellum personal assistants

  From compatibility in the SKILL.md frontmatter.

Context cost

Vellum Workspace Theme loads about 2.1k tokens when it runs. Until then it costs about 92 tokens; SKILL.md has 790 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~92

When it runs · the whole SKILL.md, loaded when a task matches

~2.1k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from vellum-ai/vellum-assistant at commit 33cc983, republished under its MIT licence (© vellum-ai). 790 words, ~2,082 tokens.

name

vellum-workspace-theme

description

Customize the app's visual theme — author design-token overrides (accent, background, surfaces, text, message-bubble colors) in the workspace ui/theme.json, validated by the assistant runtime and applied live to connected clients. Covers the token slots, the all-or-none override groups, the contrast floor, and reading back validation issues.

compatibility

Designed for Vellum personal assistants

metadata.emoji

🖌️

cat "$VELLUM_WORKSPACE_DIR/ui/theme.json" 2>/dev/null || echo "No theme yet — clients render the built-in theme"

{
  "version": 1,
  "tokens": {
    "accent": "#e8a04c",
    "background": "#1c1512",
    "surface": "#2b2018",
    "surfaceRaised": "#332619",
    "border": "#43301f",
    "text": "#f2e4d4",
    "textMuted": "#a68d75",
    "userBubbleBackground": "#26201a",
    "userBubbleText": "#efe3d2",
    "assistantBubbleBackground": "#33202a",
    "assistantBubbleText": "#ffd7e4"
  }
}

{
  "theme": { "version": 1, "tokens": { "accent": "#e8a04c" } },
  "source": "workspace",
  "issues": []
}

assistant ui snapshot --view sampler --out /tmp/theme-sampler.png
assistant ui snapshot --view chat --out /tmp/theme-chat.png

rm "$VELLUM_WORKSPACE_DIR/ui/theme.json"

© vellum-ai, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in skills/vellum-workspace-theme of vellum-ai/vellum-assistant.

Open the folder on GitHubat commit 33cc983