First MCP design contracts
open source · fail-closed
Design systems that install as MCP
Not DESIGN.md alone. Not skills alone. Each contract installs a fail-closed MCP — get_contract before UI, validate_ui before done — with markdown as the law book and skills as an optional cookbook.
Agent stack
Law book. Skills. Gates that fail the PR. MCP optional.
Inspired by how v0 grounds agents in real source and verified starters — not protocol theater. Every contract on this platform ships the same stack shape with its own DNA.
01
Law book
Required · source of truth
design.md · agents.md · DNA docs agents reread.
Persistent why, negatives, and load order per DNA. Negotiated HTML for humans, raw for machines. Not optional vibes.
- design.md
- agents.md
- docs/{id}.md
02
Verified skills
Required · cookbook
On-demand playbooks grounded in real primitives.
Every contract ships a native skill pack. Skills teach reuse and recipes — they are not a Meridian monopoly.
- {id}-compose
- {id}-theme
- specialty
03
Fail-closed gates
Required · bailiff
CI + check:* agents cannot skip.
The real enforcement. Lint bans, route parity, contrast on every skin. Done means validate is green — not that a tool was called.
- check:design
- check:platform
- check:contrast
04
Contract MCP
Optional · accelerator
Queryable kit for tool-calling sessions.
Useful when agents are MCP-wired. Never the only bailiff — schemas cost context and tools are skippable.
- get_contract
- validate_ui
- get_recipe
Why not one layer
Honest comparison
| Approach | Strength | Gap |
|---|---|---|
| DESIGN.md only | Portable prose identity | Easy to ignore · no PR fail |
| Skills only | Great procedures | Opt-in · invent APIs without catalogs |
| MCP only | Queryable tools | Context tax · agents skip tools |
| Law + skills + CI (+ optional MCP) | Context · procedure · enforcement | Slightly more surface — intentional |
Catalog
Systems — each with its own skin
Preview panes use that contract's tokens. Open the page for the full experience.
Meridian
LiveCinematic app UI for agents — OKLCH, shell rhythm, typeset, UX/DX laws.
Soft warm neutrals, one deep ink accent, full-bleed cinema, dense app chrome.
- Law book + verified skills + CI gates
- Closed grammar + check gates
- shadcn compose · typeset
- Object-bound AI rails
- Optional contract MCP accelerator
Open source · mcp/meridian
Enter system →
Harbor
PreviewCalm ops admin — dense indexes, quiet chrome, semantic status.
Quiet paper ops surfaces, semantic status chips, dense index rows — no cinema.
- Law book + harbor-* skills + CI gates
- Task density recipes for indexes
- Semantic status chips (not brand decoration)
- Index / detail intents
- Optional contract MCP accelerator
Open source · mcp/harbor
Experience DNA →
Atlas
PreviewDeveloper workbench — mono metadata, keyboard-first scanning.
Ink-forward workbench, mono metadata, keyboard-first scanning chrome.
- Law book + atlas-* skills + CI gates
- Desktop density lane
- Command-palette / jump patterns
- Mono metadata discipline
- Optional contract MCP accelerator
Open source · mcp/atlas
Experience DNA →
Vellum
PreviewReading-first docs & help — typeset lanes, measured prose.
Mist reading lanes, measured prose, typeset-first help surfaces.
- Law book + vellum-* skills + CI gates
- Typeset presets (docs / chat / reading)
- Measured prose + context budgets
- Streaming-stable copy
- Optional contract MCP accelerator
Open source · mcp/vellum
Experience DNA →
How it works
Catalog for discovery. MCP for install.
The agent stack is MCP + markdown + optional skills. This section is the install loop once you've picked a DNA.
01
Pick a design contract
This homepage is the catalog shell. Open /meridian (or Harbor, Atlas, Vellum) and the whole route becomes that DNA — proof the system is real.
02
Install the contract MCP
One npx line into any project. Agents get get_contract / validate_ui / recipes. Pair with shadcn MCP for atom delivery — different jobs.
Open Meridian install03
Compose fail-closed
Golden path: get_contract → get_recipe → list_primitives → compose → validate_ui. Creativity stays in content and composition — never new tokens.
Pricing
Open source — $0 / month
Fail-closed design-contract MCPs run on your machine over stdio — $0 COGS. Install into any project with npx; pick a DNA and agents stay inside its skin.
Cost notes live on Meridian's system doc: why we open-sourced.
What you get
- Contract MCP — required fail-closed runtime
- design.md / agents.md — law book on every contract
- Optional skills cookbook (theme · compose · cinema)
- Closed prefs via apply_prefs · shared JSON keys