Design Systems and their documentation

1) What is a design system and why is it needed

A design system is a single source of truth for an interface: a set of tokens, components, practices, and documentation that provides UX predictability, development speed, and scalability.

• Consistency of visual and behavioral layer across all products.
• Speed: reuse components, less review costs.
• Quality: general A11y patterns, localization, tests, content standards.
• Manageability: clear responsibility, releases, roadmap.

2) Design system architecture (layers)

1. Design tokens (foundation): colors, typography, dimensions, radii, shadows, indents, states, as well as semantic tokens ('color. surface. warning`, `space. xs`).
2. UI components: buttons, input fields, modal windows, dropdowns, tables, toasts, banners, alerts, empty states, skeletons.
3. Patterns and compositions: KYC forms, payment flow, zero results, step masters, content cards.
4. Content guide (microcopy): tone, dictionary of terms, error/success patterns, push/banners.
5. Infrastructure: guide to A11y, testing, localization, versions, contributors (contributing).

3) Design tokens: principles

Semantics> "raw" style. Use 'color. text. muted 'instead of' # 6B7280 '.
Themization and platforms. Source tokens → platform mappings (Web, iOS, Android, email).
Light/dark theme and WCAG contrast at the token level.
Global and contextual scales: 'space. 2`, `radius. md`, `elevation. 1`, `opacity. disabled`.
Token versioning: changes - through deprecation policy and migration notes.

4) Components: requirements and composition of the page in the documentation

• Description and purpose. When to use/not to use.
• Variants/states. Dimensions, types (primary/secondary/ghost), disabled, loading, destructive.
• Accessibility. Role, keyboard navigation, 'aria-', contrast, focus rings.
• Microcopy text and examples. Valid labels/placeholders, mistakes, help.
• Code examples. Minimal APIs, controlled/uncontrolled.
• Integration with forms and i18n. Long line cases, numbers/currencies/dates.
• Anti-examples. Erroneous usage patterns.
• Test matrix. Visual snapshots, unit/interaction, screen readers.

5) Composition patterns (Recipes)

Registration forms/CUS: step-by-step wizard, progress, validation inline + summary, error patterns.
Payment flow: method selection, fees, dates, same-method rule, confirmation and status.
Empty states: context + value + CTA, zero search results.
Success/error messages: status hierarchy, visual tokens, toast/banners/modals.
Navigation and filters: global search, quick presets, tags.
Pattern pages should show a composition of components ready for copying, with microcopy and A11y notes.

6) Content guide (voice & tone, microcopy)

Voice: professional, clear; tone depends on context (onboarding, payment, security).
Unified dictionary of terms: payments, bonuses, limits, KYC - one value per product.
Templates: CTA, errors, warnings, successes, empty states, notifications.
Localization-first: stock for the length of lines, numbers/currencies/dates by region.
A11y-vocabulary: clear labels, aria-descriptions, without ambiguities.

7) Accessibility (A11y) as a system standard

Basic criteria: WCAG 2. 1 AA for contrast, focus is always visible, keyboard navigation.
Roles and attributes: components describe 'role', 'aria-label', 'aria-describby', live regions for toasts/alerts.
On-screen readers: examples of phrases, reading order, correct statuses ('assertive/polite').
Test procedures: automatic checks + manual scripts.

8) Localization and internationalization

i18n keys next to component code + context description.
Numbers/currencies/dates through formatting utilities; do not hardcode text in templates.
Length tests: "long German," "narrow mobile," RTL variants.
Tone in languages: tone-map for critical steps (payments/security).

9) Documentation: structure and navigation

1. Introduction: mission, principles, areas of responsibility.

2. Tokens: colors, typography, grid, dimensions, shadows, states, themes.

3. Components: catalog with filters (by role, by platform, by A11y).

4. Patterns: scenarios (forms, payments, empty states, success/errors).

5. Content guide: voice and tone, dictionary, microcopy templates.

6. Accessibility: standards, checklists, test cases.

7. Localization: principles, examples, glossaries by market.

8. Integration and code: installation, versions, examples, how-to migrate.

9. Contributing: contributing processes, design review, code review, definition of done.

10. Changelog and Roadmap: releases, deprecations, development plan, known issues.

10) Governance and processes

Roles: system owner (DesignOps/UX Platform), maintainers (design/FE), consultants (BE, A11y, localization).
Change Committee: Request Evaluation, Prioritization, API/Token Reconciliation.
Processes: RFC for new components, internal issue forms, SLA for bugs.
Definition of Done: design (Figma) ↔ code (UI package) ↔ dock (example + guide) ↔ tests.

11) Contributing: how to add/change

RFC template: a problem → options → the chosen decision → A11y → i18n → migration → risks.
Flow PR: design review → code review → UX copywriter → A11y check → release notes.
Backward compatibility rules: minor/patch for non-destructive, major - with deprecation and automatic migration, where possible.

12) Versioning, releases, migrations

SemVer for packages ('@ company/ds-core', '@ company/ds-forms', '@ company/ds-charts').
Release notes: token changes, component APIs, default behavior, breaking changes, migration guides.
Deprecations: dock markups, linter rules, code mods for mass substitution.
Design-tokens pipeline: single source (JSON/YAML) → platform builds (CSS vars, iOS, Android).

13) Quality testing

Unit tests of behavior and conditions.
Visual snapshots (theme/state regression).
A11y tests: automatic + manual scripts of the screen reader.
E2E cases for critical flow (registration, payments, KYC).
Perf budgets: bundle/render limits and heavy addiction bans.

14) Design system maturity metrics

Adoption:% screens/repositories using DS.
Velocity: Time from layout to delivery.
Quality: defects UI/A11y to 1 release.
Consistency: number of "disposable" components/styles outside DS.
Docs: dock component coverage, internal audience NPS (designers/developers/analysts).

15) Anti-patterns

Tokens as a palette without semantics ("just color").
Components without documentation and without examples of extreme cases.
Ignoring A11y (no focus, low contrast, no 'aria').
Breaking versioning without deprecation and migration guide.
Hidden logic in components (business rules instead of UI behavior).
Duplication of components for narrow cases instead of API extension.

16) Checklists

• Semantic names and purpose.
• AA contrast in both themes.
• Skales and usage are documented.

• Options/states are covered.
• A11y-description, 'aria-', focus.
• Microcopy examples (labels, errors, hints).
• Code samples and edge cases (long lines, load, empty).
• Unit/visual/A11y tests are green.

• Release notes with before/after examples.
• Migration guide и deprecations.
• Updated stories/demos, links in dock.

17) Before/after examples

• Different primary buttons: colors/radii/indents do not match; different CTA texts.

• Single 'Button' with tokens: 'size = md', 'variant = primary', 'radius = lg', 'spacing = md', text in the style "action + object."

• Technical messages, no prompts.

• Component ' Invalid date format. Use DD. MM. YYYY. '+ auto-focus.

18) Component page template (skeleton)

Name: Button

Description: starts an action; 1 main per screen.
Options: primary, secondary, ghost, destructive; sm/md/lg dimensions.
States: hover, focus, active, loading, disabled.
A11y: available from the keyboard; 'aria-pressed' for switchable.

Microcopy: "Save changes," "Continue verification." Avoid "OK."

Code (example API): 'Button {variant, size, icon, loading}'.
Anti-examples: double primary at the same hierarchy level.
Tests: visual snapshots, contrast, focus-ring.

19) Design system implementation playbook (rollout)

1. Interface audit: inventory of colors/typography/components/patterns.
2. MVP tokens and major components: Button, Input, Select, Modal, Alert, EmptyState, Toast.
3. Documentation and story book: live examples, code snippets, guides.
4. Pilot product: replacing widgets, collecting feedback.
5. Migration guide: code-mods, deprecation rules.
6. Extension of the set: tables, pagination, form forums, wizard steps.
7. Scaling: product patterns (payments, KYC), integration with analytics and A/B.
8. Support: question channel, SLA, internal workshops.

20) Quick Documentation Templates

• Name: 'color. border. warning`
• Purpose: warning frames and banners Notice/Warning
• Contrast: AA against 'color. surface. default`
• Do not: use for small size text
• Related: 'color. surface. warning`, `icon. warning`

Pattern Pattern: Empty State (noResults)

Purpose: To correct a query without feeling "wrong"

Composition: heading (wholesale) , text (1-2 sentences), CTA, secondary CTA, icon/illustration

Microcopy: "Nothing was found by "{query}." Reset the filters or refine the query"

A11y: `role="status"`, `aria-live="polite"`

Final cheat sheet

Semantic tokens + discipline A11y = base.
Full component pages: purpose, variants, A11y, microcopy, code, tests.
Patterns = compositions of components with ready-made texts and rules.
Docs - product: version, releases, migrations, contribution process.
Measure maturity: adoption, speed, defects, consistency, NPS of internal commands.