Imported from fredeschmidt/tv2reg-designsystem (.agents/skills/architecture/SKILL.md). Install upstream with npx skills add fredeschmidt/tv2reg-designsystem --skill architecture. Copyright stays with the author.

Architecture

Use this skill to enforce repository architecture constraints. In component builds, this runs after design extraction and before implementation.

Mandatory Execution Rules

• Read this file before acting.
• Execute all workflow steps in exact order.
• Execute all sub-bullets under each step.
• Do not skip, combine, or reorder steps.
• If blocked or context is missing, resolve before moving on.
• When done, return to the calling skill.

Trigger

Use when implementation needs architectural guardrails for:

• components,
• tokens,
• themes/regions,
• page integration constraints.

In build flows:

• build-component-figma -> architecture -> implementation.

Do This First (Required)

1. Confirm scope type:
   • shared core change,
   • regional extension,
   • experiment.
2. Read references/token-architecture.md.
3. Read references/golden-path-workflow.md.
4. If region-specific work, read references/regional-extension-guide.md.

Repository Contract (Must Keep)

1. One shared implementation for all regions.
2. Static pages remain: index.html, article.html, design-manual.html.
3. Token source is assets/tokens.css; token consumer is assets/styles.css.
4. Runtime theme switching only in assets/theme.js.
5. Shared JS entry point is assets/script.js.
6. Each new component gets its own folder:
   • assets/components/<component-name>/
   • <component-name>.css
   • <component-name>.js only if behavior requires JS.
7. Component CSS/JS must be scoped.
8. Component CSS loads via assets/styles.css imports only (no page-level component <link> tags).
9. Component JS loads via assets/script.js only (no page-level component <script> tags).
10. No per-region HTML forks; region differences come from tokens.
11. Preserve accessible semantic structure across pages/components:

• correct landmarks,
• logical heading order,
• meaningful control semantics.

12. Component class naming must follow BEM (block__element--modifier) to keep styles predictable and scoped.

Hard Rules

1. Use tokens in component/layout CSS (var(--...)).
2. Typography in component CSS must use the new semantic type system first (--base-type-*, --base-leading-*, --base-weight-*) including family, size, weight, and line-height.
3. Do not use legacy typography aliases (--font-*) inside component styles; reserve them for compatibility in shared/global legacy layers only.
4. For Figma component builds and design-driven updates, reuse existing tokens by default.
5. Do not add new tokens unless user explicitly asks for token architecture changes.
6. Keep assets/styles.css limited to imports + shared/global rules (no component rule blocks there).
7. Keep assets/script.js as shared registry/entry for component scripts.
8. Keep theme IDs synchronized across:
   • selectors in assets/tokens.css,
   • THEMES in assets/theme.js,
   • theme picker option values.
9. Avoid page-specific inline styles/scripts.
10. Keep semantic markup stable across pages.
11. Prefer native HTML semantics first (button, a, label, input, nav, etc.); use ARIA only when native semantics cannot express the behavior.
12. Ensure interactive UI remains keyboard operable with visible focus states and no keyboard traps.
13. Ensure controls expose an accessible name and required state (aria-expanded, aria-controls, aria-current, etc.) when behavior needs it.
14. Keep non-text contrast and text contrast at WCAG AA level for default component/theme states.
15. In component CSS, prefer BEM class selectors over tag/descendant coupling to page structure.
16. Keep one canonical block per component folder and scope element/modifier classes to that block.

Safe Change Workflow (Execute In Order)

1. Define semantic need (not raw styling).
2. Choose existing token(s) in assets/tokens.css.
3. For typography, choose semantic --base-type-* + --base-leading-* + --base-weight-* tokens before introducing hardcoded font values.
4. Do not override font-size, font-weight, or line-height with raw values when semantic base typography tokens cover the use case; if unavoidable, document the exception explicitly.
5. If no exact token for the design task:
   • use closest semantic token,
   • document visual delta,
   • do not create new token by default.
6. Only if user explicitly requests, add/adjust tokens in assets/tokens.css.
7. If creating component, add assets/components/<component-name>/ and component files.
8. Import component CSS from assets/styles.css.
9. If component JS exists, register/import from assets/script.js.
10. If adding theme/region, update both:

• token override block in assets/tokens.css,
• key in assets/theme.js.

11. Validate:

• theme selector works on all pages,
• localStorage key tv2-region-theme persists,
• no hardcoded region colors in component rules,
• component/layout CSS uses --base-*/--core-* as the default token API,
• no legacy --font-* usage inside component CSS,
• no direct raw font-size/font-weight/line-height overrides where semantic base typography tokens already define them,
• component CSS/JS loading follows contract,
• semantic structure is valid (landmarks, heading order, labels),
• interactive behavior is keyboard accessible with visible focus,
• ARIA usage (if any) matches actual behavior/state and is not redundant with native semantics,
• text and interactive UI contrast satisfy WCAG AA,
• component classes follow BEM consistently (block, element, modifier),
• no cross-component selector coupling that breaks BEM scoping,
• mobile and desktop render correctly.

Output Requirements

When done, report:

1. Constraints applied.
2. Architecture decisions made.
3. Files that must be touched (or avoided).
4. Any rule conflicts/blockers and how they were resolved.