Explore radically different design approaches for any page, component, or feature. Use when the user wants to compare multiple distinct visual directions side by side — not build one specific thing, but see several fundamentally different takes on the same UI. Signals: "explore designs for", "show me different ways to design", "radically different approaches", "what could this look like", "design exploration", "let's see some options before we commit", "different layout approaches", "different visual identities for the same content", wanting to see multiple families or variations before choosing a direction. Also triggers when the user pastes design exploration feedback (starts with "## Design Exploration Feedback") to iterate on a previous round, or pastes a design direction ("## Design Direction") to finalize. Do NOT trigger for building one specific design, visual refreshes, design critiques, brainstorming without visual output, single widget prototypes, or comparing CSS frameworks.
Installation
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Explore radically different design approaches for any page, component, or feature. Use when the user wants to compare multiple distinct visual directions side by side — not build one specific thing, but see several fundamentally different takes on the same UI. Signals: "explore designs for", "show me different ways to design", "radically different approaches", "what could this look like", "design exploration", "let's see some options before we commit", "different layout approaches", "different visual identities for the same content", wanting to see multiple families or variations before choosing a direction. Also triggers when the user pastes design exploration feedback (starts with "## Design Exploration Feedback") to iterate on a previous round, or pastes a design direction ("## Design Direction") to finalize. Do NOT trigger for building one specific design, visual refreshes, design critiques, brainstorming without visual output, single widget prototypes, or comparing CSS frameworks.
Design Exploration
Generate a single self-contained HTML file presenting distinct design variations (scaled to scope — see Step 2) with per-variation interactive controls, a rating/feedback system, and structured export. The goal is divergent thinking: explore fundamentally different approaches to a design problem before converging on a direction. "Different" means different on the right axis — usually different interaction models, not different visual themes.
When to Use
Before brainstorming, to anchor a greenfield discussion with visual options
After brainstorming, to explore how requirements could look/feel before tech planning
Standalone, when someone wants to see design options for any page, component, or feature
When iterating on a previous round of explorations (user pastes feedback from export)
Key Principles
Diverge before converging — The point is to explore fundamentally different approaches. But "different" must be on the right axis: different interaction models for functional problems, different visual identities for aesthetic problems. A neon terminal and a boutique card layout that have identical form flows are NOT different where it matters.
Multiple rounds are normal — The first round is broad exploration. Subsequent rounds refine based on feedback. The skill supports this loop natively.
The direction doc is the durable output — HTML galleries are working artifacts. The design direction document captures what was chosen and why.
Standalone or in-workflow — Works independently or as part of the brainstorming → tech-planning pipeline. Adapts handoff based on context.
Process
Detect context (always first) — check for existing explorations before responding. Resume, iterate, or fresh start.
Understand the request — only for fresh explorations. What is being designed, for whom, divergence axis, constraint level
Plan the variations — variations across families, count scaled to scope, divergent on the right axis
Generate the HTML file — gallery with variations, controls, ratings, metadata, export
Conclude — when the user converges, capture the design direction
File Structure
All artifacts for an exploration live in a dated topic directory:
docs/design-explorations/YYYY-MM-DD-<topic>/
v1.html ← first round
v2.html ← refined round
v3.html ← further refinement
docs/design-directions/
YYYY-MM-DD-<topic>-design-direction.md ← written at conclude
Step 0: Detect Context (MANDATORY — runs first, before ANY response to the user)
Your very first action must be detection — before any Q&A, scoping questions, or even acknowledging the request. Do NOT skip to Step 1 without completing the checks below.
0a. Check for feedback input
If the user's message contains structured feedback (ratings, reference to a previous exploration file), this is an iteration round. Extract the Source: path from the feedback, then read the metadata from that HTML file (see "Reading prior metadata" in Step 3). This gives you the families, variations, and round number. Proceed to Step 2 with both the feedback and the metadata as context.
0b. Check for existing explorations
Before responding to the user, check what's in docs/design-explorations/. If any existing exploration looks relevant to the user's request, tell them you found it and ask whether to iterate or start fresh. If iterating, read the previous round's metadata (see Step 3). Proceed to Step 2 — skip Step 1 entirely. If nothing relevant exists, proceed to Step 1.
Step 1: Understand the Request
Input can range from a single sentence ("explore designs for a notification system") to a full PRD. The goal of this step is to gather enough context that the approach-based divergence planning in Step 2 produces meaningfully different directions — not random ones.
This step only runs for fresh explorations (no feedback input, no existing exploration to iterate on). If Step 0 found a previous round to iterate on, skip this step — the metadata provides the context.
Adaptive scoping
Ask 0-2 scoping questions based on how much ambiguity exists. When a PRD or detailed requirements already exist (e.g., from iterative:brainstorming), the problem space is already mapped — determine the divergence axis from the existing context and proceed to Step 2. The PRD informs the exploration but doesn't constrain the creative surface; the whole point is to discover visual and interaction possibilities the requirements alone can't express.
When input is lighter (a sentence or brief description), component prompts tend to describe the full problem; larger scopes tend to leave more genuinely open. The right questions inform the exploration — the wrong ones constrain it. The test: does knowing the answer change which approaches you'd explore, or does it just eliminate options the user should see? If it eliminates options, don't ask — let the exploration show them.
Scope surfacing
When input covers multiple distinct UI surfaces (e.g., a PRD describing a dashboard, an upload flow, a settings page, and an image grid), identify the surfaces and ask the user what to explore. Present options including exploring everything (full scope) as a first-class choice, plus focused options for individual surfaces or natural groupings. Frame it as "I see these surfaces — want to explore all of them, or focus on a subset?" — not "pick exactly one." Keep it to a single question.
When input is already narrow (a single component, one screen, one flow), skip this — there's nothing to scope.
What you need to know before proceeding (infer from context when possible)
Divergence axis — interaction, visual, or both? (see below — usually obvious from context)
The goal — what problem is being solved
Who — audience and their context (obvious for components, worth asking for full pages)
Constraint level — greenfield or fitting into an existing app?
Divergence Axis
The divergence axis determines WHAT varies between families. This is the most important decision — getting it wrong produces explorations that are visually impressive but practically useless.
Interaction divergence (DEFAULT) — Families explore different ways the thing WORKS. Different behavior, flow, information architecture, progressive disclosure, state handling. All variations share a clean, professional visual treatment — a realistic neutral UI that looks like it belongs in a real product. The user is comparing interaction models, not color palettes.
Default for: components, features, anything inside an existing app, anything with a clear functional problem to solve
Example: "price input with sale toggle" → one family uses inline toggle that reveals fields, another uses side-by-side comparison, another uses a stepped wizard, another shows a live storefront preview. All look like a professional admin panel.
Example: "notification center" → drawer vs popover vs inline expansion vs full-page view. All share the same visual language.
Visual divergence — Families explore different ways the thing LOOKS. Same functional structure (or a simple reference structure), different aesthetics, typography, spatial composition, atmosphere. Useful for establishing visual identity when there IS no existing design language.
Use for: landing pages, brand exploration, design system foundations, or when the user explicitly asks to explore visual styles
Example: "landing page for a new product" → one family is brutalist editorial, another is luxury minimal, another is playful illustrated
This mode triggers the full creative typography, color, and atmosphere treatment
Both — Families differ in both visual identity AND interaction model. Only appropriate when the entire page or app is open — no existing design system, no existing interaction patterns, full greenfield.
Use for: full-page or full-app greenfield explorations where both visual identity and interaction model are genuinely open questions
Rare — most explorations have at least some constraints or a clear functional problem that makes interaction the primary axis
How to determine the axis:
Signal
Axis
"explore different ways to [do X]"
Interaction
Component or feature scope
Interaction
Mentions an existing app, screen, or design system
Interaction
Has a clear functional problem to solve
Interaction
"explore visual styles for...", "what should it look like"
Visual
Landing page, marketing site, brand identity
Visual
Full page, no existing app, no functional constraints
Both
When in doubt, default to interaction. Wild visual divergence on a functional problem (like a price input rendered as a neon cyberpunk terminal) is rarely useful. Interaction divergence is almost always what people need — they want to see different UX approaches, rendered professionally, so they can make a decision about how the thing should work.
Constraint Level
Orthogonal to the divergence axis — this determines whether visual choices are locked to an existing system or open.
Within an existing app — Visual language is locked. Axis is always interaction.
Establish the visual boundaries. Ask for or infer: color palette, font stack, border-radius, spacing scale, component patterns.
Create a shared visual base. All variations share font families, colors, radius, spacing, button/input styles via shared CSS custom properties.
Simulate the surrounding context. Render each variation inside a mock of the existing app — same header/nav/shell across all variations; only the explored area differs.
Shift controls to UX dimensions. Per-variation controls focus on behavioral parameters (animation style, disclosure model, density) — not color and font (those are locked).
Greenfield — No existing app or design system. The divergence axis determines how much visual freedom each variation gets.
Interaction axis (greenfield): use a clean, professional visual base (one good font pairing, neutral palette) across all variations. Families differ in how the thing works.
Visual axis (greenfield): full creative freedom per family — different typography, colors, spatial composition.
Both axes (greenfield): families differ in everything — visual identity, layout, and interaction model.
Step 2: Plan the Variations
How many variations?
The variation count scales with the design space — how many meaningfully different approaches exist for the problem. Don't default to 6 every time; don't inflate to 12 when the scope doesn't warrant it.
Minimum 2 families, minimum 2 variations per family
Round 2+ counts drop because feedback narrows the space — drop families the user rejected, go deeper on ones they liked
When in doubt, 6 is a safe default for most explorations. Only go higher when the scope genuinely has more axes of divergence to explore.
Feedback-driven iteration planning
When planning Round 2+ from user feedback, use these principles to translate ratings, notes, and control adjustments into a concrete plan for the next round. These aren't rigid rules — the agents are smart enough to make good judgment calls given the right framing.
Reading the feedback signal
Each rating tier tells you something directional:
Loved (4-5★): The approach resonated. Refine it, don't replace it. User notes on loved variations are specific preferences to carry forward — they've moved past "do I like this?" to "here's what I'd tweak."
Mixed (2-3★): Something worked, something didn't. The notes are the key — they usually say exactly what to keep and what to fix. Don't drop mixed variations; extract the good part and fold it into a refined or new family.
Skip (0★): Equally strong signal as Loved — the user actively rejected this direction. Drop the family entirely. But read the notes carefully: skip notes are constraints on the entire next round, not just the dropped family. "Too many things are hidden" means all future approaches need visible affordances. "Not a great UX" for a guided flow means don't try guided flows again. Every skip note is a global constraint.
User notes are design requirements
When notes say things like "I'd like the model to be selectable" or "needs a way to add reference images" — those aren't suggestions, they're requirements for the next round. Fold them into the variation briefs for agents. A note on a loved variation ("love this but needs a dimensions input") becomes a requirement in every variation of that family's next iteration.
Control adjustments carry forward
When the exported feedback shows a user moved a control from its default (e.g., sidebar width 240→300px, density compact→spacious), use those adjusted values as the new defaults in the next round's variation briefs. The user already told you what they prefer — start there.
The exploration-convergence balance
Each round should feel like it's narrowing AND discovering. A round that only refines what worked feels like diminishing returns. A round that ignores feedback feels like it wasn't listening.
Keep at least one family slot for a genuinely new approach the user hasn't seen — even in Round 3+. The new approach should be informed by what worked (if the user loved a sidebar layout, the new approach might also use a sidebar — but with a fundamentally different interaction model). This prevents the exploration from collapsing too early while still feeling responsive to feedback.
Direction for Next Round
When the user fills in the "Direction for Next Round" section of the export, that's the highest-signal input — it overrides tier-based inference. If the direction says "focus on A1 and make it production-ready," that's a refinement round, not an exploration round. If it says "I liked A1 but want to see completely different aesthetics," that's a visual-axis pivot. Plan accordingly.
When the direction is empty ([No direction provided]), fall back to the tier-based planning above.
Worked example
Suppose Round 1 explored an image generation tool with three families:
A "Sidebar Studio" — sidebar with controls, canvas preview. A1 got 5★ ("love the layout, needs a dimensions input"), A2 got 4★ ("clean but want model selection").
B "Split Workspace" — two-panel with prompt on left, preview on right. B1 got 3★ ("like the prompt area, too cramped"), B2 got 2★ ("good idea for history panel but execution is cluttered").
C "Guided Flow" — step-by-step wizard. C1 got 0★ ("not a great UX for creative work"), C2 got 0★ ("too rigid").
Round 2 plan:
Family A (refine): 2-3 variations. Carry forward the sidebar layout. Every variation must include dimensions input (A1 note) and model selection (A2 note). Explore variations within the sidebar concept — maybe one with a collapsible settings panel, one with inline controls.
Family B→A hybrid (extract and merge): 1-2 variations. B1's prompt area was liked — take that element and apply it to A's sidebar layout. The "history panel" idea from B2 could become a sidebar tab.
Family D (new): 2 variations. A genuinely new approach. Informed by what worked: uses visible affordances (C's skip notes said guided/hidden UX was rejected), incorporates a prompt area (B1's liked element). Maybe "What if it worked like a command palette with live preview?" — different interaction model, but respects the constraints.
Drop C entirely. The skip notes ("not a great UX for creative work," "too rigid") become global constraints: no wizard-style flows, no rigid step sequences.
Approach-based divergence planning
Before deciding families, identify the specific design question the exploration is answering — then brainstorm different answers to it.
The axis from Step 1 (interaction vs visual) determines the visual treatment: interaction-axis variations share a neutral professional style; visual-axis variations get full creative freedom. But within the chosen axis, the specific question is what makes the exploration focused and useful. "Explore different ways a price input works" is too broad — "explore different mental models for how a user sets a sale price" is specific enough to produce meaningfully different families.
Interaction axis (default): Each approach is a different answer to the design question — articulable as "What if [specific concept]?" The concept should evoke a UX pattern, mental model, or interaction philosophy — not a visual aesthetic.
Visual axis: Each approach is a different way the thing LOOKS — articulable as "What if it felt like [aesthetic / brand / product]?" Full creative divergence on typography, color, spatial composition.
Both axes: Approaches differ in both how it works AND how it looks. The concept evokes a complete product mental model.
Process:
Brainstorm 4-6 approaches. Frame each as a question appropriate to the axis:
Interaction-axis examples:
"What if prices were side-by-side for direct comparison?" (dual-column, always-visible, comparison-first)
"What if the sale was a mode toggle that reveals progressive detail?" (compact by default, expanding)
"What if there was a live storefront preview next to the inputs?" (WYSIWYG, immediate feedback)
"What if pricing was a stepped flow?" (wizard-style, guided, one question at a time)
Visual-axis examples:
"What if it felt like a Bloomberg Terminal?" (dense, data-forward, dark, monospace)
"What if it felt like a magazine spread?" (editorial, image-heavy, serif, generous whitespace)
Both-axes examples:
"What if it worked like a command palette AND felt like a terminal?" (search-first + monospace dark)
"What if it was a guided conversation AND felt like a luxury checkout?" (progressive disclosure + refined, minimal)
Push past obvious references. The first approaches that come to mind are usually the most familiar — Notion, Linear, Slack, Shopify. These are fine as one data point but they're not exploration. Draw from outside the usual tech product vocabulary: print design, architecture, game UI, industrial controls, analog tools, other industries entirely. The goal is to surface approaches the user hasn't already considered.
Select 2-3 approaches that are most divergent from each other. Two approaches are divergent if they imply different answers to fundamental questions: What's visible first? How does the user interact? Where does complexity live? What's the primary flow?
Articulate what makes each approach different before assigning families. Don't just name the concept — state the concrete implications: what's prominent, what's hidden, how the user moves through the content, what the interaction prioritizes.
CRITICAL for interaction axis: Approaches must differ in BEHAVIOR, not aesthetics. "Nordic Ledger" and "Neon Terminal" sound different but might have identical interaction patterns — different paint on the same UX. "Side-by-side comparison" and "progressive disclosure wizard" ARE different — fundamentally different interaction models regardless of visual treatment. When the axis is interaction, name the UX pattern, not the aesthetic.
Scale to scope:
Full page / major feature: Approaches differ in layout, navigation, information architecture, and (for visual/both axes) visual identity. Many axes of divergence.
Component / small scope: Approaches differ primarily in interaction model and progressive disclosure. Fewer axes, but interaction differences matter more. A component rarely needs visual-axis divergence.
Naming
Each family (approach) receives:
Code: LETTER + NUMBER — Letter = family, Number = member (A1, A2, B1, B2, C1, C2, C3)
Memorable name: Evokes what makes this approach distinctive. For interaction axis, name the UX concept ("Progressive Reveal", "Side-by-Side Compare"). For visual axis, name the aesthetic ("Boutique Ivory", "Neon Markdown"). People say "I liked the progressive reveal one" — not "I liked B1."
Layout label and Aesthetic label (for interaction axis, the aesthetic label describes the interaction style, e.g., "Progressive Disclosure", "Compact Dense")
Design thinking per variation
Commit to a clear direction for each family before writing HTML. The divergence axis determines what to decide.
Interaction model: Fundamentally different per family — inline editing vs. modal, click-to-expand vs. always-visible, drag-and-drop vs. button actions, wizard vs. single form.
Information architecture: Different content organization, hierarchy, progressive disclosure strategy.
State handling: Different approaches to empty states, loading, errors, edge cases.
Visual treatment: All variations share a clean, professional visual base. Pick ONE good font pairing and neutral palette for the entire exploration. Variations look like they belong in the same product — the differences are in how they work, not how they're painted. Professional and polished, not bland — think of a well-designed SaaS admin panel.
Motion: Animation STYLE can differ — spring physics vs. sharp cuts, vertical vs. horizontal motion. Hover transitions, open/close animations, micro-interactions ARE the design at component scale.
Differentiation: What interaction or UX choice will someone remember? (Not what color or font.)
Visual axis — aesthetic divergence:
Tone: Pick an extreme per family — brutally minimal, maximalist, retro-futuristic, editorial, brutalist, luxury, playful, industrial, etc.
Typography pairing: Distinctive display font + refined body font per family. Never reuse pairings. Never use Inter, Roboto, Arial, or system fonts.
Spatial signature: What makes this layout unforgettable? Generous whitespace? Asymmetric grid? Overlapping elements? Diagonal flow?
Atmosphere: Go beyond flat backgrounds — but express it in 1-2 CSS effects, not 10. A single gradient + subtle shadow is more effective than stacking every technique.
Motion: At minimum: hover transitions on interactive elements + one entrance animation per variation.
Differentiation: Articulate the one memorable thing about this variation before building it.
Both axes — full divergence:
Combine interaction and visual thinking above. Each family differs in both how it works AND how it looks.
Components — scale the thinking regardless of axis:
Atmosphere = how the component FEELS to interact with, not page-level visual depth.
Motion matters MORE at component scale — hover transitions, open/close animations, micro-interactions ARE the design.
Controls focus on component-scale parameters: padding, radius, shadow, animation timing, label placement. Not page-level concerns.
Variation quality rules
Families must represent fundamentally different approaches — not variations on a theme. If you can't articulate what each approach's concept is, the families aren't divergent enough.
Divergence must be on the right axis. For interaction-axis explorations: families that look different but work the same way is a FAILURE (e.g., neon terminal vs. boutique card layout, but both have identical form fields in the same order). For visual-axis explorations: families that look the same but have different names is a failure.
Same realistic data across all variations. Compelling, real-sounding content (never lorem ipsum). Same data = fair comparison.
Each must be memorable on the chosen axis. Interaction axis: indistinguishable after 10 seconds of interaction = too similar. Visual axis: indistinguishable at a glance = too similar. Push harder.
Include at least one unexpected approach. A pattern from a different domain, an unconventional interaction model, something the user probably hasn't considered.
Design-preview quality, not production build. Show the IDEA of the design efficiently. A well-composed preview with 3-4 content items beats a bloated one with 12 repetitive cards. For interaction-axis explorations, the preview must make the interaction model obvious even in a static mockup — use state indicators, clear affordances, and layout that implies the flow.
Per-variation design controls
Each variation gets 4-8 controls that let the user explore design decisions without generating a whole new variant. Controls modify CSS custom properties on the variation's iframe.
The litmus test: if someone across the room can't tell the control changed something, it's too subtle. Each control should represent a decision a designer would credibly debate. Switching between options should produce a visibly different result.
Start with what makes this variation unique. The most valuable controls expose the decisions specific to THIS variation's structure and interaction model. Two variations with different interaction models should have mostly different controls.
Interaction-axis explorations: Lead with behavior controls. Disclosure speed, animation style, label placement, validation display mode, information density, field grouping, element visibility, progressive disclosure threshold. These are the controls that let someone experience how the interaction model feels at different settings.
Visual-axis explorations: Lead with aesthetic controls. Color mood (not a single warm/cool preset, but 2-3 independent color dimensions the user can mix), typography personality, gradient intensity, texture density, contrast level.
Structure-specific controls (include only when the variation has the element):
Structure element
Controls
Sidebar
Width (range), Position (left/right), Collapse toggle
Card grid
Columns (2/3/4), Gap size, Card style (bordered/shadow/flat)
Content area
Max width (narrow/medium/wide/full)
Hero section
Height (range), Alignment (left/center)
Table/list
Row density, Stripe toggle, Border style
Full-page additions (optional, only for full-page scope): For full pages, you may add 1-2 global controls like spacing density or content width if they meaningfully reshape the layout. For components, skip these entirely; they're noise at component scale and eat the control budget.
| Borders | Style (none/subtle/visible), Radius (range) |
Control data model schema:
// Range control — value + unit are set directly on the CSS var
{
id: 'sidebar-width', // unique within variationlabel: 'Sidebar Width', // human-readabletype: 'range', // range | select | togglemin: 180, max: 320, step: 10,
options: null,
value: 240, // current value (REQUIRED — never null/undefined)defaultValue: 240, // reset targetunit: 'px', // appended to value when setting CSS varcssVar: '--sidebar-width'// CSS custom property this modifies
}
// Select — single property (e.g. accent color):
{
id: 'accent',
label: 'Accent Color',
type: 'select',
min: null, max: null, step: null,
options: ['coral', 'teal', 'indigo', 'amber'],
cssValues: { coral: '#e07a5f', teal: '#4a9e8f', indigo: '#5c6bc0', amber: '#d4a853' },
value: 'teal',
defaultValue: 'teal',
unit: '',
cssVar: '--accent'// single var: --accent: #4a9e8f
}
// Select — MULTI-VAR (e.g. mood changes bg + text + borders together):
{
id: 'mood',
label: 'Mood',
type: 'select',
min: null, max: null, step: null,
options: ['light', 'dark', 'midnight'],
cssValues: {
light: { '--bg': '#faf9f7', '--text': '#2d2a26', '--text-dim': '#8a8580', '--border': '#e5e0d8' },
dark: { '--bg': '#1e1e2a', '--text': '#e0ddd8', '--text-dim': '#8a8580', '--border': '#333340' },
midnight: { '--bg': '#0d0d14', '--text': '#c8c4be', '--text-dim': '#6a6660', '--border': '#1e1e2a' }
},
value: 'light',
defaultValue: 'light',
unit: '',
cssVar: null// multi-var: no single var, cssValues objects set all vars
}
// Toggle — cssValues maps true/false to CSS values:
{
id: 'show-dividers',
label: 'Show Dividers',
type: 'toggle',
min: null, max: null, step: null,
options: null,
cssValues: { true: '1px', false: '0px' },
value: true,
defaultValue: true,
unit: '',
cssVar: '--divider-width'
}
Key rules for controls:
id is REQUIRED — unique within the variation. Without it, the control renders but clicking/dragging does nothing. (The template auto-generates from label as a safety net, but don't rely on this.)
value and defaultValue must ALWAYS be set (never null/undefined)
Range controls: value is numeric, unit is appended → --gap: 24px. Exception: never use unit: '%' for percentage-scale ranges — use unitless values (e.g., 0-100 or 0-1) and let the CSS handle the math (calc(var(--opacity) / 100) or calc(var(--opacity) * 1%)). The % unit in CSS var output causes calc() failures.
Select controls: MUST include cssValues mapping options → CSS values. Without it, the CSS var gets a label string like --bg: warm which is useless
Toggle controls: SHOULD include cssValues mapping true/false → CSS values. Without it, defaults to 1/0
Multi-var controls — when one control needs to change multiple CSS properties (e.g. mood/mode changing background, text, and borders together), use an object as the cssValues value instead of a string. Set cssVar: null. See the "mood" example above.
Every control must represent a meaningful design decision. Controls let the user explore a design dimension without needing a whole new variant. The test: can someone across the room tell the control changed something? If not, it's too subtle. Bad: switching between near-identical off-whites, 2px radius changes, shadow opacity going from 6% to 8%. Good: compact vs spacious density (reshapes the layout), rounded vs sharp corners (changes the personality), warm vs cool color mood, showing vs hiding a secondary element, gradient direction, animation style.
Every cssVar must be used in the variation. The HTML must reference it via Tailwind arbitrary values (e.g., bg-[var(--bg)], rounded-[var(--radius)]) or the CSS must use it. If a control defines --card-radius but the HTML uses rounded-xl, the control does nothing. The assembly script validates this and prints warnings.
ALL visual states must use var() for controlled properties. Hover, active, and focus states must reference CSS vars, not hardcoded values. If --accent is #BB6BD9, don't write :hover { color: #BB6BD9 } — write :hover { color: var(--accent) }. Use color-mix() for derived colors: color-mix(in srgb, var(--accent) 10%, transparent).
Never use [style*="..."] attribute selectors for CSS variable detection. Attribute selectors are fragile for detecting CSS custom property values and should not be used.
Step 3: Generate the HTML File
Generate a single self-contained HTML file (~3000-5000 lines total) using Tailwind CSS Play CDN + Alpine.js CDN + Google Fonts. This step uses parallel html-prototyper agents to generate variation content, keeping context windows small and variation quality high.
Before creating files, check if the directory already exists. If it does:
User provided feedback from a previous round (pasted export with ratings/direction) → this is an iteration. The feedback's Source: line gives the HTML path. Extract its metadata with the same sed command from "Reading prior metadata" below to get the families array and variations array. Create v{N+1}.html where N is the round value from the metadata.
No feedback provided, but directory has existing files → ask the user:
"I found an existing exploration at docs/design-explorations/YYYY-MM-DD-<topic>/ with v1.html. Would you like to continue iterating (creates v2.html) or start fresh?"
If continue: create the next vN.html. Extract the metadata from the latest existing round to avoid repeating previous designs (see "Reading prior metadata" below).
If start fresh: create a new directory with a disambiguating suffix: YYYY-MM-DD-<topic>-2/. This preserves the original exploration.
Directory doesn't exist → create it and generate v1.html.
Round detection:
Check for existing v*.html files: ls docs/design-explorations/YYYY-MM-DD-<topic>/v*.html 2>/dev/null
Or read from the feedback input's metadata block ("round": N)
Next round = highest existing round + 1
Reading prior metadata (continue without feedback):
When the user chooses to continue in an existing directory but hasn't provided feedback, extract the metadata from the latest round's HTML to learn what was already explored. Use sed to pull just the JSON block — do NOT read the full file:
sed -n '/<script type="application\/json" id="exploration-metadata">/,/<\/script>/p'"{exploration_dir}/v{latest}.html" | sed '1d;$d'
This gives you the families array (each family's approach concept) and the variations array (each entry's layoutType, aesthetic, familyName, name, and description). Use this to:
Understand what approaches were tried — the families[].approach field captures the "What if it worked like...?" concept behind each family
Avoid repeating the same approach or layout × aesthetic pairings — if v1 explored "What if it worked like a magazine article?", don't try that again
Diversify family directions — if v1 explored 2 families, aim for 2-3 different families in the continuation
Reference what was tried — include a "previousVariations" summary in the new round's metadata so the chain is traceable
Include the prior family approaches and variation summary in each agent prompt as a "do not repeat" constraint:
Previous round explored these approaches (do NOT recreate these):
- Family A "Editorial Manifesto": What if it worked like a long-form magazine article? → Sidebar + Cards layout, Clean Light aesthetic
- Family B "Interactive Product Stage": What if the product demo was the hero? → Stacked Full Width layout, Dark Dramatic aesthetic
Generate something with a fundamentally different approach.
Generation Architecture
The file is too large for a single agent to generate well — quality degrades across multiple variations in one context. Split the work:
You (the orchestrator, Opus) handle:
Writing _metadata.json (the only file the orchestrator creates directly)
Spawning html-prototyper agents with complete prompts
Running assemble.py which copies the template, injects all content, and produces the final HTML
One variation each — generating a single self-contained HTML file with embedded metadata and controls
Spawned in parallel since variations are independent
Each agent writes exactly one file (_var-{ID}.html) in one turn
Step 3a: Understand the Shell (do NOT read reference files)
The shell template (references/shell-template.html) is a complete gallery page with three placeholders: __METADATA_JSON__, __VARIATIONS_ARRAY__, and __VARIATION_TEMPLATES__. Each variation's HTML is a complete page rendered inside an <iframe srcdoc>. The assembly script copies the template, wraps each _var-{ID}.html file in a <template id="tpl-{id}"> element, and fills all placeholders automatically — the orchestrator never reads it. Do NOT read any files in references/ — all essential rules are in this document, and assemble.py handles the template. Reading plugin reference files triggers avoidable permission prompts.
Step 3b: Spawn html-prototyper Agents
For each planned variation, spawn an html-prototyper agent in the background with write permissions. Launch all agents in a single message so they run in parallel.
Critical — permissions: The agent frontmatter declares permissionMode: acceptEdits, but this does NOT propagate automatically on all platforms. You MUST explicitly grant write/file permissions when spawning. Platform examples:
Claude Code: Use the Agent tool with subagent_type: "iterative-engineering:html-prototyper", mode: "bypassPermissions", and run_in_background: true.
Codex: Use spawn_agent with write permissions enabled. The agent only needs the Write tool.
Other platforms: Use whatever mechanism your platform provides to spawn a background agent with file-write permissions.
Waiting for agents — MANDATORY PATTERN:
After spawning all agents, you MUST wait for each one using your platform's blocking agent-output mechanism. Do NOT use sleep, ls, or any bash polling.
Claude Code example:
# In a single message, call TaskOutput for each background agent:
TaskOutput(task_id=<agent_1_id>, block=true, timeout=300000)
TaskOutput(task_id=<agent_2_id>, block=true, timeout=300000)
... one per agent, all in parallel
Codex: Use wait to block until each spawned agent completes, then close_agent to release it. Call wait for each agent before proceeding to assembly.
Other platforms: Use whatever your platform provides to block until a background agent completes. The key requirement is: do NOT proceed to assembly until every agent has finished writing its file.
NEVER use sleep N && ls to check if files exist. This is the single most common orchestrator mistake. It wastes tokens, adds latency, triggers permission prompts, and can proceed before agents finish writing.
Prompt structure for each agent:
The agent has the design-prototyping skill preloaded, which contains the complete file format, control schema, styling rules, and pre-output checklist. The orchestrator prompt only needs variation-specific content. Keep it lean.
Write {exploration_dir}/_var-{ID}.html. Follow the design-prototyping loaded in your context.
CRITICAL: The metadata block MUST use exactly id="variation-meta" — this ID is machine-parsed by the assembly script.
Then include ONLY:
The variation brief — id, family, familyName, name, layoutType, aesthetic, description, what makes it memorable, the key design commitments for this variation
The shared realistic data — the exact content (names, numbers, descriptions) to use. Keep this compact — just the data, no surrounding context about the project
The divergence axis and constraint level — one sentence establishing both. For interaction-axis explorations, explicitly state: "Visual treatment is shared — use [font pairing] and [palette description]. Focus on making the INTERACTION MODEL distinct, not the visual style." For visual-axis, state: "Full creative freedom on visual treatment — make the aesthetic distinctive and memorable."
The controls brief — list the 4-6 controls for this variation. For each: label, type, cssVar, and the range/options. For behavioral controls (sort order, filter thresholds, expansion mode), add "event": true — this tells the agent the control needs a JS event listener, not just a CSS var. The agent knows the schema from its preloaded skill; you just specify WHICH controls this variation gets and their parameters.
Size guidance — state explicitly. Scale to scope: a full page needs ~400-600 lines; a component needs ~250-350. The mockup must look like a real product, not a wireframe.
Data density — state explicitly how much realistic data to include. For agent/user rosters: "populate at least 5-6 items with varied states." For dashboards: "show at least 8-10 data points." For lists: "include enough items to demonstrate scrolling and density." Sparse data makes explorations look like wireframes.
Scope-specific note (if component) — "Center content in the viewport: min-h-screen flex items-center justify-center p-8 on <body>."
Do NOT repeat the file format, control schema, styling rules, or checklist in the prompt. The agent already has these from the design-prototyping skill. Repeating them wastes tokens and increases context pressure.
The goal: a self-contained prompt under ~1000 words. The agent generates content and writes one file.
Step 3c: Assemble the Final File
The orchestrator assembles via the standalone assemble.py script — it does NOT read variation file contents into its own context. This is critical for scaling to many variations without the orchestrator itself hitting context limits.
Write the metadata JSON to {exploration_dir}/_metadata.json (the orchestrator generates this — it's small)
Run the assembly script — a single bash command. The {skill_base} path is the "Base directory for this skill" shown when the skill loads. Run the command directly (don't verify the path first — that triggers permission prompts).
python3 "{skill_base}/references/assemble.py""{exploration_dir}" {round} "{skill_base}/references/shell-template.html" && open "{exploration_dir}/v{round}.html"
The script handles everything:
Copies the shell template to v{round}.html
Validates each _var-{ID}.html exists and contains a valid variation-meta JSON block
Validates HTML files have no orphaned </template> close tags (balanced nesting is safe)
Extracts metadata/controls from each HTML file's embedded JSON block
Wraps each HTML file in a <template id="tpl-{id}"> element
Replaces all three template placeholders
Reports exit code 1 (missing files or metadata), 2 (validation failure), or 0 (success)
Cleans up all temp files (_var-*.html, _metadata.json)
If the script reports missing files (e.g. "B1: missing or invalid variation-meta"), do NOT try to fix this by reading existing files and generating the missing ones. That approach reads variation content into the orchestrator's context and defeats the whole architecture. Instead:
Delete the partial output for that variation: rm -f {exploration_dir}/_var-{ID}.html
Re-spawn the specific agent with the same prompt
If the script reports validation errors (e.g. "orphaned </template> close tags"), delete the variation's output and re-spawn with a note to ensure every <template> open tag has a matching close tag.
The orchestrator's context only holds the conversation, the metadata JSON (small), and one bash command. It never reads the variation files.
Metadata Block
Include a <script type="application/json" id="exploration-metadata"> block in the HTML <head>:
{"project":"Dashboard","topic":"dashboard","round":2,"date":"2026-02-18","previousRound":"v1.html","sourceDirectory":"docs/design-explorations/2026-02-18-dashboard","families":[{"letter":"A","name":"Horizontal Flow","approach":"What if it worked like a social media feed — infinite scroll, cards, algorithmic ordering?"},{"letter":"B","name":"Command Center","approach":"What if it worked like a Bloomberg terminal — dense, data-forward, keyboard-driven?"}],"previousVariations":[{"family":"A","familyName":"Sidebar Classic","layoutType":"Sidebar + Cards","aesthetic":"Clean Light"},{"family":"B","familyName":"Bold Editorial","layoutType":"Stacked Full Width","aesthetic":"Dark Dramatic"}],"variations":[{"id":"A1","family":"A","familyName":"Horizontal Flow","name":"Nordic Mist","layoutType":"Top Nav + Masonry","aesthetic":"Muted Scandinavian","description":"Horizontal navigation with masonry content grid in cool muted tones."}]}
The families array captures the conceptual approach behind each family — the "What if it worked like...?" framing from Step 2. This is included in the feedback export so the next round's agent understands what was tried and can iterate meaningfully. The previousRound field maintains the iteration chain. The previousVariations field (included when continuing without feedback) records what was explored in earlier rounds so agents can avoid repeating the same directions.
Feedback Export
The export modal (built into the shell template) produces a markdown document optimized for LLM consumption. Per variation it includes: the family approach concept ("What if it worked like...?"), layout/aesthetic labels, the variation description, user notes, and control adjustments showing direction of change (default → adjusted value). Grouped by rating tier (Loved/Mixed/Low/Skip/Not reviewed). Designed to be pasted back into the agent to trigger the next round. The format spec is documented in references/export-formats.md (for human reference — do not read at runtime).
Reference Files (do NOT read at runtime)
These files exist for human maintenance and for assemble.py to consume. The orchestrator must NOT read them — doing so triggers avoidable permission prompts. All rules the orchestrator needs are inlined in this document.
references/shell-template.html — Gallery shell template. Consumed by assemble.py, never by the orchestrator.
references/html-architecture.md — Architecture spec for maintainers. Essential rules are inlined in this skill file.
references/export-formats.md — Export format spec for maintainers. The export modal is built into the template.
Step 4: Conclude
The user finalizes from the gallery by clicking "Ship It" on their chosen variation, then pastes the direction output into the conversation. The skill handles everything from there.
"Ship It" (rating bar) — finalizes the currently viewed variation as the chosen direction
When the user clicks "Ship It", the gallery generates a ## Design Direction block containing the chosen variation's family approach, description, and adjusted design specs (absolute values). The user adds notes and copies it to paste into the conversation.
When the user pastes ## Design Direction
The skill detects the header and runs the conclude sequence:
Read metadata — extract the Source: path from the pasted text. Read the metadata from the HTML file using sed (same as Step 0/3). This gives full context: families, approaches, all variations, round count.
Write direction doc — create docs/design-directions/YYYY-MM-DD-<topic>-design-direction.md using the template below. Combine the pasted direction data with metadata context.
PRD integration — if a PRD exists, add a reference line (**Design Direction:** [path]). If no PRD, the direction doc stands alone.
Handoff — depends on how the skill was invoked:
Invoked from iterative:brainstorming: Write the direction doc, then exit. Do NOT present handoff options — iterative:brainstorming owns the workflow and will resume its own flow with the updated context (direction doc now exists, PRD references it).
Invoked standalone: Write the direction doc, then present an interactive choice:
Continue to iterative:brainstorming — define requirements around the chosen direction (when no PRD exists)
Continue to tech planning — plan the implementation (when PRD exists or requirements are clear enough)
Explore more — another round of design exploration
Done for now — exit
Direction Document Template
# Design Direction: [Topic]**Date:** YYYY-MM-DD
**Rounds:** N
**Gallery:** vN.html
## Chosen Direction### [Variation code] "[Name]" — [Layout Type / Aesthetic]**Approach:** [Family approach concept — "What if it worked like...?"]
[What works about this direction. Key design decisions — interaction model,
layout structure, typography, color direction, etc. Include adjusted design specs
if the user changed controls from defaults. Include any notes the user added.]
## Design Parameters
<!-- Cross-cutting decisions worth carrying forward.
Only include if the exploration surfaced clear preferences.
Skip this section entirely if there are none. -->
## Context
<!-- Include when standalone (no PRD). Skip when a PRD provides the context. -->
[What prompted this exploration. The problem being solved. Who it's for.]
Quality Bar
Each variation is MEANINGFULLY different on the chosen axis — interaction axis: different UX flow or interaction model; visual axis: different layout structure and aesthetic
Switching variations is instant (no janky reflows)
Per-variation controls update the preview in real time with smooth transitions
Each variation has 4-8 controls RELEVANT to its specific structure, with each control producing a visible change
Behavioral controls (sort, filter, threshold) use "event": true and have JS listeners in the variation
Same realistic data across all variations, with sufficient density (not sparse wireframe-like content)
Star ratings persist across page reloads
Export produces a single markdown document with JSON ratings, summary, and editable direction
All keyboard shortcuts work
Gallery shell matches the fixed template exactly — same tokens, fonts, layout, and behavior as every other exploration file
Gallery shell is dark and RECEDES — eyes go to the variations, not the chrome
File works by opening directly in a browser (no build step, no server)
Each variation has a memorable name
Visual axis: no two families use the same font pairing. Interaction axis: all families share a professional visual base
At least one variation is unexpected/creative
Metadata block is present and accurate
File is named with correct round number in the exploration directory
Common Mistakes
Visual divergence on a functional problem (THE #1 mistake) — When asked to explore a component or feature (e.g., "price input with sale toggle"), generating a neon cyberpunk version, a developer terminal version, and a boutique card version is NOT useful. Those are visually different but may have identical interaction patterns. The user wants to see different ways the pricing UX WORKS — inline toggle vs wizard vs side-by-side comparison — all rendered in a clean, professional style. Default to interaction-axis divergence. Only go visually wild when the user is explicitly exploring visual identity.
Variations are just color swaps — Each family needs fundamentally different HTML structure or interaction model. Not the same tree with different colors.
Controls don't work — Common causes: (1) missing id field — control renders but clicks do nothing (template auto-fixes this but don't rely on it); (2) cssVar: '--card-radius' defined but HTML uses rounded-3xl instead of rounded-[var(--card-radius)] — the var is set but nothing reads it; (3) unit: '%' on a range control breaks calc() in CSS (use unitless values for percentage scales); (4) hover/active states use hardcoded colors instead of var(--accent) — the default state changes but hover doesn't; (5) cssValues written as an array instead of an object — cssValues: ['0.75rem', '1rem'] MUST be cssValues: { compact: '0.75rem', comfortable: '1rem' } keyed by option labels (the template auto-fixes this but don't rely on it). Controls are applied via iframe.contentDocument.documentElement.style.setProperty(). The assembly script warns about orphaned CSS vars.
Controls drive CSS classes instead of CSS vars — The control system sets CSS custom properties via setProperty(). For visual controls, all styling must flow through var() references. For behavioral controls that need DOM manipulation (sorting, filtering, showing/hiding sections), mark them "event": true and add a control-change event listener in the variation's JS. See the design-prototyping skill for the pattern.
Same controls on every variation — Each variation's controls should reflect its unique structure. If 4 out of 6 controls are identical across all variations (e.g., every variation has spacing-density, font-scale, card-radius, accent-color), the controls aren't doing their job. The most valuable controls are the ones unique to a specific variation's interaction model. Especially for components: skip boilerplate controls like spacing density and font scale, and dedicate all controls to the design decisions specific to that variation.
Generic AI aesthetics (visual axis) — No Inter + purple gradients on white. Distinctive, intentional choices. Reference real products. Note: this applies to visual-axis explorations. For interaction-axis explorations, a clean professional style IS the goal — the aesthetics should be polished but not distracting from the UX being explored.
Lorem ipsum — Real content only. "$1,247,890 in revenue" beats "Lorem ipsum dolor sit amet."
Export is just raw data — The export must produce a ready-to-paste markdown prompt with structured JSON ratings, a human-readable summary, and a user-editable direction section.
Too many controls — 4-8 per variation.
Controls too subtle to notice — If someone across the room can't tell the control changed something, it's too subtle. Common traps: page background switching between near-identical off-whites, corner radius changing by a few pixels, shadow opacity going from 6% to 8%. Each control should surface a design decision someone would actually care about. "Do we want this compact or spacious?" reshapes the layout. "Should the shadow be 6% or 8% opacity?" is invisible. Gradient direction, color mood, element visibility, animation style, density, disclosure model: these produce visible, debatable differences.
Missing Google Fonts — Every variation HTML file must include its own Google Fonts <link> in <head>. Each variation is a complete page inside an iframe and loads its own fonts.
Missing metadata block — Every HTML file needs the exploration-metadata JSON block for agent consumption.
Shell chrome varies between files — The gallery shell is a fixed product. Same design tokens, fonts, layout, and interaction across every file. Only the variations inside the preview stage differ. The template enforces this automatically.
Reading reference files at runtime — Never read files in references/ during skill execution. The orchestrator has everything it needs in this document, and assemble.py handles the template. Reading plugin files triggers permission prompts that interrupt the user.
Generating all variations in the orchestrator — Don't skip the agent pattern. Variation quality degrades when one agent generates all variations sequentially. Each variation deserves a focused agent.
Orchestrator reading variation content into context — The orchestrator must assemble via bash/python file operations, not by reading each agent's output. Reading 7 × 500-line files into the orchestrator's context will cause it to hit context limits during the write step.
Inconsistent data across variations — The orchestrator must include the same realistic data set in every agent prompt. If agents invent their own data, variations can't be fairly compared.
Agent or orchestrator context overflow — The html-prototyper agent is pre-configured with maxTurns: 1 to prevent multi-turn exploration. Include size guidance (HTML page 250-600 lines depending on scope). Critically, the orchestrator must NOT read variation file contents into its own context — use the file-based assembly pattern (bash/python to replace template placeholders with file contents). If the orchestrator reads all 7 variation files, it will hit context limits during assembly.
Custom CSS instead of Tailwind — When an agent writes margin-top: 24px; padding: 16px; border-radius: 12px; background: var(--bg); as custom CSS, it should be mt-6 p-4 rounded-xl bg-[var(--bg)] in a Tailwind class string. Custom CSS is only for property definitions, keyframes, transitions, and things Tailwind genuinely can't express. Use Tailwind utility classes in the HTML and keep <style> blocks compact.
Orphaned </template> in variation HTML — The assembly script wraps each file in a <template> element. Orphaned (unbalanced) </template> close tags break the wrapper. Balanced <template> nesting is safe (e.g., Alpine.js <template x-for>, <template x-if>) — the HTML parser closes the nearest open <template>, not the outer wrapper. The assembly script validates this: it strips <script> blocks (where </template> in string literals is inert), counts opens vs closes, and only errors if closes > opens.
Controls that don't visibly change anything — The most common quality issue. A control may be wired correctly (CSS var is set) but produce no visible change because: (a) the range is too narrow (radius 8-12px is invisible), (b) the property has no visual impact in context, or (c) the control is behavioral but has no JS listener. The design-prototyping skill includes a mandatory QA step — agents must audit each control's visible impact before finishing.
Sparse data making explorations look like wireframes — Agent prompts must specify minimum data counts. A 6-agent roster with one agent per status state tells a story; 2 agents with the same state looks like a skeleton. Include explicit data density guidance in every agent prompt.
Missing or invalid variation-meta block — Every HTML file must contain a <script type="application/json" id="variation-meta"> block in <head> with valid JSON. The assembly script extracts this to build the variations array. If the block is missing or contains invalid JSON, assembly fails.
CSS scoped by class instead of :root — Variations are isolated in iframes. Define custom properties on :root, not on .v-a1. Class-scoped properties won't be reached by setProperty() on documentElement.
Missing transition CSS — Each variation HTML must include the transition CSS rule (:root * { transition: ... }) for smooth control changes. Without it, control adjustments appear as jarring instant changes.
Interim files not cleaned up — The assembly script handles cleanup automatically. If you're not using the script, always run rm -f _var-*.html _metadata.json after assembly.
Color controls as a single theme preset — A single "warm/cool/neutral" select is too blunt. Prefer 2-3 independent color dimensions the viewer can mix. Use multi-var cssValues (object format) when one control needs to change multiple properties together.
Orchestrator reading variation files to fix partial output — If an agent wrote a partial or invalid HTML file, do NOT read it to "understand what's needed." This reads variation content into the orchestrator's context. Instead, delete the file and re-spawn the agent.
Wrong round number — Check existing files in the directory before naming.
Unnecessary filesystem checks — Don't verify plugin file paths (ls, find) before running commands. Run commands directly.
Sleep-polling for agent completion (THE #2 mistake) — Never use sleep N && ls to check if agents finished. Use your platform's blocking mechanism to wait for each agent (Claude Code: TaskOutput(task_id=<id>, block=true, timeout=300000) for each agent in a single message; Codex: wait + close_agent for each spawned agent). This is mandatory, not a suggestion. sleep && ls wastes minutes of wall time, burns tokens on repeated bash calls, and can proceed to assembly before an agent finishes writing.
