SvelteKit 2

Overview

Use this skill for SvelteKit-specific concerns: file-based routing, load functions, actions, endpoints, invalidation, and app-level testing/CLI. For component internals (runes, props, events, styling/accessibility), load the companion svelte5 skill alongside this one.

Quick start

• Check repo conventions: .github/AGENTS.md, .github/AGENTS-SVELTE.md, .github/AGENTS-SVELTE-JSDocs.md (and .github/AGENTS-SEO-GEO.md for SEO tasks).
• Choose file type intentionally: +page/+layout (UI), +page.server (server-only data/actions), +page (universal load), +server (API endpoint).
• Validate inputs in loads/actions/endpoints; use fail(status, data) for validation errors, error for exceptional cases. Sanitize any HTML before @html.
• Wire error handling early: throw via error/redirect, provide +error.svelte routes, and wrap risky components with <svelte:boundary> or shared ErrorBoundaries for graceful fallbacks.
• Hydration: prefer event.fetch inside loads; return serializable data; after mutations use invalidate or action results instead of ad-hoc client fetches.
• Testing/builds: rely on repo scripts; see references for commands. When component logic changes, also use svelte5 patterns.

Workflow

1. Map route boundaries: what data is needed server-only vs shared, which mutations/actions exist, and which components consume it (svelte5 covers component detail).
2. Implement load functions following references/kit-patterns.md: pick universal vs server load, handle error states explicitly, avoid leaking secrets to the client.
3. Add form actions for mutations with validation and friendly failures via fail; wire use:enhance for progressive enhancement when desired.
4. Build endpoints with explicit method exports, validation, and json/Response returns; set headers/cache deliberately.
5. Post-mutation: refresh UI via invalidate/invalidateAll or returned action data; avoid redundant fetches in components.
6. Run checks from references/testing-and-cli.md (lint/format/build/tests). Add Playwright when routing or user journeys change.

Cross-skill guidance

• For component APIs, runes, events, snippets, styling, and accessibility, load svelte5 with this skill.

References

• references/kit-patterns.md — project setup, hooks/locals/context, load functions, actions/remote functions, advanced routing, forms, adapters, CSP, and performance patterns.
• references/testing-and-cli.md — CLI commands (lint/build/test) and Vitest/Playwright tips for this repo.