Imported from Martino17x/Sentinel-Invest (.agents/skills/skills-design/design-brief/SKILL.md). Install upstream with npx skills add Martino17x/Sentinel-Invest --skill design-brief. Copyright stays with the author.

Design Brief Skill

Parse a structured design brief into a concrete DESIGN.md and optional visual preview. Agent, follow this workflow exactly.

Background

The 8 dimensions in this skill are derived from analysis of the 71 design systems bundled with Open Design. Every DESIGN.md in design-systems/ resolves at minimum: color palette, accent, typography, display font, layout model, and component style. We distilled these into 8 orthogonal dimensions that cover the decisions a designer makes before any pixel is placed. Mood and density were added because they are the two most common sources of ambiguity in natural language briefs ("make it clean" means different things to different people).

Dimensions intentionally excluded from the brief level: animation timing, responsive strategy, and accessibility contrast. These are enforced at the template level by individual skills (e.g., saas-landing handles its own responsive logic), though the generated DESIGN.md includes sensible breakpoint defaults for downstream consumption.

1. Accept input

The user provides a design brief in one of two formats:

Option A: I-Lang structured brief

[PLAN:@DESIGN|type=saas_landing]
  |palette=navy_and_white|accent=coral
  |typography=inter|display=space_grotesk
  |layout=single_column|max_width=1200px
  |mood=professional_minimal
  |density=spacious|section_gap=96px
  |hero=headline+subhead+cta
  |sections=features,pricing,testimonials,footer
  |exclude=animations,parallax,gradients
  |responsive=mobile_first

Option B: Natural language

"I need a landing page for a developer tool. Clean, minimal, dark mode. Inter font. No flashy animations."

If the user provides Option B, convert it to the structured format using the mapping table below, then proceed. Identify every dimension explicitly stated and flag dimensions that were left unspecified.

Natural language → I-Lang mapping

For each sentence in the natural language input, identify dimension keywords and map to the closest structured value:

When a phrase maps to multiple dimensions (e.g. "clean dark landing page" → mood=professional_minimal + palette=monochrome_dark + layout=single_column), resolve each dimension independently. When multiple values are listed for a single mapping, the first is the default; the agent may select the alternative only if surrounding context strongly favors it.

2. Validate dimensions

Every design brief must resolve these 8 dimensions. If any are missing from the input, select sensible defaults using the rules in Section 2.2.

The values listed below form a closed vocabulary. Only values in this table have concrete token mappings in Section 2.1. If the user provides a value not listed here, the agent must prompt for clarification rather than guessing.

2.1 Symbolic → concrete token resolution

Each symbolic value maps to concrete design tokens. The agent must resolve these before writing DESIGN.md:

Symbolic values not in this table are not valid. If the user provides an unrecognized value (e.g., palette=ocean_blue), the agent must prompt for clarification: "I don't recognize palette=ocean_blue. Did you mean navy_and_white, monochrome_dark, light_clean, or earth_tones?"

2.2 Default resolution rules

When a dimension is unspecified, defaults are selected based on mood compatibility:

If mood is also unspecified, all defaults fall back to the safe neutral set: palette=light_clean, accent=electric_blue, typography=inter, display=same_as_body, layout=single_column, mood=professional_minimal, density=balanced, exclude=none.

3. Generate DESIGN.md

This skill generates a new DESIGN.md from scratch based on the resolved brief dimensions. If a DESIGN.md already exists in the working directory, the agent should ask the user whether to overwrite or skip.

Produce a DESIGN.md following Open Design's 9-section convention. All color hex values, font stacks, and spacing values must come from the resolved tokens in Section 2.1 — do not invent values outside the resolution table.

# [Project Name] Design System

## Visual Theme & Atmosphere
- Mood: [resolved from mood]
- Feel: [derived from mood — e.g., professional_minimal → "Clean, confident, restrained"]
- References: [if mood=editorial → "Magazine layouts, Monocle, Cereal"; if mood=brutalist → "Exposed structure, raw typography"]

## Color Palette & Roles
- Background: [resolved from palette]
- Surface: [resolved from palette]
- Text primary: [resolved from palette]
- Text secondary: [resolved from palette]
- Accent: [resolved from accent]
- Accent hover: [resolved from accent]

## Typography Rules
- Display: [resolved from display], 700, clamp(2rem, 5vw, 3.5rem)
- Body: [resolved from typography], 400, 1rem/1.6
- Mono: JetBrains Mono, 400, 0.875rem

## Component Stylings
- Buttons: [if mood=playful → "rounded-full", otherwise → "rounded-md"], accent bg, contrast text
- Cards: surface bg, subtle border, 12px radius
- Inputs: [if mood=brutalist → "thick border", otherwise → "transparent bg, bottom border"]

## Layout Principles
- Max width: 1200px
- Grid: [resolved from layout]
- Section spacing: [resolved from density]
- Content padding: [resolved from density]

## Depth & Elevation
- Shadows: [if mood=brutalist → "hard 4px offset", if mood=professional_minimal → "none", otherwise → "subtle sm"]
- Borders: 1px solid [derived from palette, 8% opacity of text color]

## Do's and Don'ts
- DO use the declared color tokens exclusively.
- DO maintain consistent section spacing.
- DO ensure all text meets WCAG AA contrast ratio.
- DON'T invent colors outside the palette.
- DON'T add decorative shadows unless Depth & Elevation allows them.
- DON'T use more than 2 display/body typefaces (monospace is a utility face for code and data — it does not count toward this limit).

## Responsive Behavior
- Breakpoints: 640px (sm), 768px (md), 1024px (lg), 1280px (xl)
- Mobile: single column, stack all sections vertically
- Tablet: allow 2-column feature grids
- Desktop: full layout with max-width constraint
- Images: fluid, max-width 100%, maintain aspect ratio

## Agent Prompt Guide
- Do NOT invent colors outside this palette.
- Do NOT add box-shadows unless specified above.
- Accent color appears maximum 3 times per viewport.
- All interactive elements need :focus-visible outline.
- [if exclude contains items → list each as "Do NOT use {item}."]

4. Generate brief-preview.html

Create a single HTML file that visually renders the resolved design tokens. The preview must contain these 4 sections in order:

1. Color palette swatches — A horizontal row of rectangles, each showing one color from the Color section. Label each with its role (Background, Surface, Text, Accent) and hex code.
2. Typography specimens — Three text blocks showing Display, Body, and Mono fonts at their declared sizes. Use a sample sentence ("The quick brown fox...") for each.
3. Spacing ruler — A visual ruler or stacked bars showing section spacing and content padding values, labeled with their px values.
4. Component preview — Render 2–3 live components (a primary button, a card with title/body, a text input) using the resolved tokens. These should be functional HTML/CSS, not screenshots.

Style the preview itself with the resolved design system tokens (background color, font, spacing). The preview should look like a design system documentation page.

5. Report unspecified dimensions

At the end of output, list any dimensions the user did not specify and the defaults that were applied, including the rule that selected each default:

Dimensions resolved from defaults:
- display: set to "same_as_body" (rule: mood=professional_minimal → same_as_body)
- density: set to "balanced" (rule: static fallback, no spacing preference given)
- exclude: set to "none" (rule: no constraints unless specified)

This transparency prevents silent assumptions from propagating into the final design.