Mneme HQ preserves design system decisions for AI-assisted UI development by surfacing design tokens, component hierarchy rules, and accessibility requirements at prompt time. When an LLM generates frontend code that invents a non-approved color, bypasses a required component, or ignores WCAG guidelines, Mneme HQ flags the violation before the code reaches review. Rules files document standards. Mneme enforces them.
Reference Architecture · Simulated Scenario

# Using Mneme HQ to Preserve Design System Decisions for AI Builders

Stop AI assistants from inventing colors, breaking component hierarchy, and ignoring accessibility rules every time they generate a UI.

Install Mneme HQ View GitHub
The Problem

## AI-generated UI ignores your design system every session.

Your design system defines which colors are approved, which components must be used for which patterns, how spacing works, and what accessibility requirements apply. An AI assistant generating JSX has no awareness of any of it — it invents inline styles, reaches for arbitrary Tailwind classes, skips ARIA attributes, and creates one-off components instead of using existing ones.

Design system violations are expensive to catch in review and easy to miss entirely. They accumulate into inconsistent UIs that erode user trust and multiply future remediation work.

Without Mneme HQ — assistant generates:
Prompt: "Add a confirmation modal for account deletion"
I'll create a new Modal component with a red #ff0000 confirm button and inline styles for the overlay. I'll add the text directly without using the existing Typography component...
With Mneme HQ — pre-flight check:
mneme check --mode strict
✗ FAIL decision/use-approved-components
Rule: Use Modal from design-system/Modal, not custom implementations.
✗ FAIL decision/no-hardcoded-colors
Rule: Colors must reference design tokens. #ff0000 is not an approved token.
✗ FAIL decision/destructive-actions-require-aria
Rule: Destructive action modals require role="alertdialog" and aria-describedby.
→ Surfaced 3 violations before code generation.
Why Existing Tools Fall Short

## Storybook and linters don't prevent violations at generation time.

Approach | Limitation | With Mneme HQ
--- | --- | ---
Storybook docs | Documents components; doesn't enforce which ones AI must use | Component usage rules encoded as enforceable decisions
ESLint / Stylelint | Catches known anti-patterns in written code; can't encode design rationale | Design intent and constraints captured with full context
Figma / design files | Not accessible to AI at code-generation time | Design token rules surfaced at prompt time
Design review | End-of-sprint; expensive; inconsistencies already embedded | Violations flagged before a component is written

How Mneme HQ Solves It

## Design constraints enforced before the first JSX line.

1

#### Encode design system rules as decisions

Capture approved tokens, required components, spacing rules, and accessibility requirements as structured YAML decisions.

2

#### Check before generating UI code

Run `mneme check` against your UI prompt. Relevant design decisions are retrieved and any violations flagged immediately.

3

#### Inject design rules into assistant context

Generate a rules file for Cursor or Claude Code that includes your design system constraints — so every UI generation session is token-aware.

4

#### Gate frontend PRs on design compliance

Add `mneme check --mode strict --tags design-system` to CI. PRs introducing unapproved tokens or missing accessibility attributes fail automatically.

Technical Implementation

## What design system decisions look like.

decisions/design-tokens.yml

    id: no-hardcoded-colors
    title: All colors must reference design tokens
    status: accepted
    rule: No hardcoded hex, rgb, or hsl values in component code.
      Use CSS variables from tokens.css or Tailwind config approved keys only.
    rationale: Hardcoded colors break dark mode, theming, and brand consistency.
      Introduced after brand refresh caused 200+ manual color fixes.
    enforcement: strict
    tags: [design-system, tokens, frontend]

decisions/accessibility.yml

    id: destructive-actions-require-aria
    title: Destructive action modals require ARIA alertdialog role
    status: accepted
    rule: Any modal confirming a destructive action must have role="alertdialog",
      aria-labelledby, and aria-describedby set.
    rationale: WCAG 2.1 AA compliance requirement. Failed accessibility audit in Q1.
    enforcement: strict
    tags: [design-system, accessibility, wcag, frontend]

Terminal — checking a UI generation prompt

    $ mneme check "add a delete account confirmation modal" --tags design-system

    Checking against 12 design-system decisions...

    ✗ FAIL decision/use-approved-components (Modal exists in design-system/)
    ✗ FAIL decision/no-hardcoded-colors
    ✗ FAIL decision/destructive-actions-require-aria
    ✓ PASS decision/spacing-must-use-scale
    ✓ PASS decision/typography-component-required

    Result: FAIL (3 violations, strict mode)

Simulated Outcome

## What design teams see after enforcement goes live.

~0
hardcoded color values in AI-generated UI after enforcement
100%
of captured design rules enforced automatically in CI
Fewer
design review comments on token and accessibility violations after enforcement
These figures are based on a simulated reference scenario — not live customer data.
FAQ

## Common questions.

Does this expand Mneme HQ beyond backend engineering?
Yes. Design system governance is one of the clearest examples of Mneme HQ's value for frontend and full-stack teams. Any discipline with enforced conventions — design, data, security — benefits from the same decision-enforcement model.
Can designers manage decisions without engineering involvement?
Yes. Decision YAML files are plain text in version control. Designers can open PRs to add token rules, component requirements, or accessibility constraints without writing any code.
How do we handle design system evolution — new components, deprecated ones?
Update the YAML. Set old decisions to `status: deprecated` to stop enforcing them. Add new decisions for new components. The version history in git serves as your audit trail of design system changes.
Does this work with Tailwind, CSS Modules, and CSS-in-JS?
Yes. Mneme HQ enforces intent, not implementation. Your decisions describe what's allowed — the AI assistant uses whatever styling approach your project uses, constrained by those rules.
Related Use Cases
Coding Assistant Governance → Data Platform Governance → Multi-Agent Workflow Governance →