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SvelteKit + Drizzle + Tailwind rules for AI coding agents

Full stack: SvelteKit (Svelte 5) + Tailwind CSS v4 + Drizzle ORM + Vitest

Ready-to-commit rules for SvelteKit (Svelte 5) + Tailwind CSS v4 + Drizzle ORM + Vitest in every major format: AGENTS.md (Codex, Cursor, Copilot), CLAUDE.md (Claude Code), Cursor .mdc project rules, legacy .cursorrules, Copilot instructions, Windsurf rules and GEMINI.md. SvelteKit full-stack with Drizzle ORM.

Last reviewed 2026-10-21 · Customise in the generator · Raw: AGENTS.md, CLAUDE.md

The mistake agents make most on this stack

Agents run `drizzle-kit push` against production instead of committing migrations.

Generated files

AGENTS.md
# AGENTS.md - this project

Instructions for AI coding agents working in this repository.

## Project

A SvelteKit (Svelte 5) + Tailwind CSS v4 + Drizzle ORM + Vitest project.

Stack: SvelteKit (Svelte 5), Tailwind CSS v4, Drizzle ORM, Vitest.

## Commands

- Dev server: `npm run dev`
- Build: `npm run build`
- Type check: `npm run check`
- Generate migration: `npx drizzle-kit generate`
- Apply migrations: `npx drizzle-kit migrate`
- Unit tests: `npx vitest run`

## Project structure

- Routes in `src/routes/` (`+page.svelte`, `+page.server.ts`, `+layout.svelte`, `+server.ts`).
- Shared code in `src/lib/` (import as `$lib/...`), server-only code in `src/lib/server/`.

## How to work in this repo

- Read the relevant files before editing. Follow the patterns already in the codebase over these generic rules.
- Make the smallest change that solves the task. Do not refactor or reformat unrelated code.
- Before saying a task is done, run the type-check, lint and tests listed under Commands and fix what you broke.
- If requirements are ambiguous, ask one clear question instead of guessing.
- Never commit secrets, API keys or `.env` files. Use env vars and keep `.env.example` up to date.
- Do not add a new dependency when the standard library or an existing dependency already covers it.
- Ask before adding, removing or upgrading any dependency.
- Ask before changing database schemas, auth, payments or CI configuration.
- Never delete files, drop data or run destructive commands (`rm -rf`, `git push --force`, `DROP TABLE`) without explicit approval.
- Keep each change under ~200 changed lines where possible; split larger work into steps.

## SvelteKit (Svelte 5)

- Use Svelte 5 runes: `$state`, `$derived`, `$effect`, `$props`. Do not use legacy `export let` or `$:` syntax in new code.
- Prefer `$derived` over `$effect` for computed values. Use `$effect` only for real side effects.
- Load data in `+page.server.ts` / `+layout.server.ts` `load` functions, not in `onMount`.
- Handle form submissions with form actions and `use:enhance`.
- Read secrets from `$env/static/private` or `$env/dynamic/private`, only in server files.
- Use `error()` and `redirect()` from `@sveltejs/kit` for control flow in load functions and actions.

## Tailwind CSS v4

- Tailwind v4 is configured in CSS: `@import "tailwindcss";` plus `@theme { ... }` for design tokens. Do not create a `tailwind.config.js` unless the project already has one.
- Use theme tokens (colors, spacing) instead of arbitrary values like `w-[37px]`.
- Build responsive layouts mobile-first with `sm:`, `md:`, `lg:` prefixes.
- Extract repeated class lists into components, not `@apply` chains.
- Support dark mode with the `dark:` variant when the project uses it.

## Drizzle ORM

- Schema lives in TypeScript (`db/schema.ts`). Generate SQL migrations with `drizzle-kit generate` and commit them.
- `drizzle-kit push` is for local prototyping only, never for production databases.
- Infer types with `typeof table.$inferSelect` / `$inferInsert` instead of duplicating interfaces.
- Use the query builder or `sql` template tag; never build SQL with string concatenation.
- Use `db.transaction()` for multi-step writes.

## Vitest

- Co-locate tests next to the code as `*.test.ts(x)`.
- Test behaviour through public APIs; for components use Testing Library queries by role/label.
- Mock network calls at the boundary (e.g. MSW) rather than mocking internal modules.
- Every bug fix adds a test that fails without the fix.

## Reference docs

- [SvelteKit docs](https://svelte.dev/docs/kit)
- [Svelte 5 runes](https://svelte.dev/docs/svelte/what-are-runes)
- [Tailwind CSS docs](https://tailwindcss.com/docs)
- [Drizzle docs](https://orm.drizzle.team/docs/overview)
- [Vitest docs](https://vitest.dev)

Commands your agent should run

TaskCommand
Dev servernpm run dev
Buildnpm run build
Type checknpm run check
Generate migrationnpx drizzle-kit generate
Apply migrationsnpx drizzle-kit migrate
Unit testsnpx vitest run

What the rules cover

SvelteKit (Svelte 5)

SvelteKit with Svelte 5 runes and TypeScript. Scoped to src/**/*.svelte, src/**/*.ts in Cursor, Copilot and Windsurf.

  • Use Svelte 5 runes: $state, $derived, $effect, $props. Do not use legacy export let or $: syntax in new code.
  • Prefer $derived over $effect for computed values. Use $effect only for real side effects.
  • Load data in +page.server.ts / +layout.server.ts load functions, not in onMount.
  • Handle form submissions with form actions and use:enhance.
  • Read secrets from $env/static/private or $env/dynamic/private, only in server files.
  • Use error() and redirect() from @sveltejs/kit for control flow in load functions and actions.

Source docs: SvelteKit docs, Svelte 5 runes

Tailwind CSS v4

Utility-first styling with Tailwind CSS v4. Scoped to **/*.css, **/*.tsx, **/*.vue, **/*.svelte, **/*.astro, **/*.html, **/*.blade.php, **/*.erb in Cursor, Copilot and Windsurf.

  • Tailwind v4 is configured in CSS: @import "tailwindcss"; plus @theme { ... } for design tokens. Do not create a tailwind.config.js unless the project already has one.
  • Use theme tokens (colors, spacing) instead of arbitrary values like w-[37px].
  • Build responsive layouts mobile-first with sm:, md:, lg: prefixes.
  • Extract repeated class lists into components, not @apply chains.
  • Support dark mode with the dark: variant when the project uses it.

Source docs: Tailwind CSS docs

Drizzle ORM

SQL-like TypeScript ORM with drizzle-kit migrations. Scoped to db/**/*.ts, src/db/**/*.ts, drizzle/** in Cursor, Copilot and Windsurf.

  • Schema lives in TypeScript (db/schema.ts). Generate SQL migrations with drizzle-kit generate and commit them.
  • drizzle-kit push is for local prototyping only, never for production databases.
  • Infer types with typeof table.$inferSelect / $inferInsert instead of duplicating interfaces.
  • Use the query builder or sql template tag; never build SQL with string concatenation.
  • Use db.transaction() for multi-step writes.

Source docs: Drizzle docs

Vitest

Unit and component tests with Vitest. Scoped to **/*.test.ts, **/*.test.tsx, **/*.spec.ts in Cursor, Copilot and Windsurf.

  • Co-locate tests next to the code as *.test.ts(x).
  • Test behaviour through public APIs; for components use Testing Library queries by role/label.
  • Mock network calls at the boundary (e.g. MSW) rather than mocking internal modules.
  • Every bug fix adds a test that fails without the fix.

Source docs: Vitest docs

How to install

  1. Copy AGENTS.md to your repo root. That covers Codex, Cursor, GitHub Copilot and most other agents.
  2. Using Claude Code? Add a CLAUDE.md with the single line @AGENTS.md, or use the standalone CLAUDE.md tab above.
  3. Want rules that only load for certain files in Cursor? Add the .cursor/rules/*.mdc files.
  4. Commit the files so your whole team (and every agent) shares them.

FAQ

Where do I put the AGENTS.md for SvelteKit (Svelte 5) + Tailwind CSS v4 + Drizzle ORM + Vitest?

Save it as AGENTS.md in the root of your repository, next to your main config file. Codex, Cursor and GitHub Copilot pick it up automatically. For Claude Code, add a CLAUDE.md containing @AGENTS.md (or use the standalone CLAUDE.md on this page).

What is the most common mistake AI agents make with SvelteKit (Svelte 5)?

Agents run drizzle-kit push against production instead of committing migrations.

Which commands should the agent run to check its work?

For this stack: npm run dev, npm run build, npm run check, npx drizzle-kit generate. They are listed in the generated files so the agent runs them before finishing a task.

Do these SvelteKit (Svelte 5) + Tailwind CSS v4 + Drizzle ORM + Vitest rules work with Cursor and Claude Code?

Yes. This page includes the same rules as AGENTS.md, CLAUDE.md, Cursor .mdc project rules, a legacy .cursorrules file, GitHub Copilot instructions, Windsurf rules and GEMINI.md.

Can I customise these rules?

Yes. Open this stack in the generator to add or remove libraries, set your project name and package manager, switch beginner explanations on, and download everything as a zip.

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