A set of coding guidelines for Svelte 5 and SvelteKit, tools for building web applications with Svelte. It explains current syntax for components, state, routing, and rendering.

Use it when creating, editing, reviewing, or debugging Svelte components, Svelte modules, or SvelteKit projects.

It helps keep Svelte code aligned with current conventions and avoids older patterns when newer ones are recommended.

with-svelte — Skill for Claude Code by robcsaszar/frontend-kit

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add robcsaszar/frontend-kit --skill with-svelte

Clone the repo

git clone --depth 1 https://github.com/robcsaszar/frontend-kit

Made for: Claude Code.

Or install robcsaszar-frontend-kit, the plugin that ships this one along with the rest of its 4 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/robcsaszar/frontend-kit/with-svelte/github.svg)](https://agentmods.dev/skills/robcsaszar/frontend-kit/with-svelte)

Your own site

<a href="https://agentmods.dev/skills/robcsaszar/frontend-kit/with-svelte"><img src="https://agentmods.dev/badge/skills/robcsaszar/frontend-kit/with-svelte/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/robcsaszar/frontend-kit/with-svelte"><img src="https://agentmods.dev/badge/skills/robcsaszar/frontend-kit/with-svelte.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 249 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,992 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00249	$0.01992
Opus 5.5	$0.00100	$0.00797
Sonnet 5.5	$0.00050	$0.00398
Haiku 4.5	$0.00025	$0.00199

Measured 1mo ago against content hash 67341cf5a3e5, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

with-svelte scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/with-svelte/SKILL.md · 87 lines

How it starts

The opening of the file, as written. The whole thing — 87 lines — stays where its author put it; the contents beside it link to each section on GitHub.

with-svelte

Unified Svelte 5 + SvelteKit skill. This body is a router: apply the always-on core below, then READ the one reference file that matches the task before writing code. Load only the file(s) you need — not all of them.

Always-on core (every Svelte task)

Write runes-mode Svelte 5. Never reach for a legacy feature that has a modern replacement:

$state instead of implicit let count = 0; count += 1
$derived/$effect instead of $: — and prefer $derived over $effect (effects are an escape hatch; never set state inside one)
$props instead of export let, $$props, $$restProps
onclick={...} instead of on:click={...}
{#snippet}/{@render} instead of <slot>, $$slots, <svelte:fragment>
{@attach ...} instead of use:action
<DynamicComponent> instead of <svelte:component this={...}>; import Self instead of <svelte:self>
classes with $state fields instead of stores; createContext instead of setContext/getContext
clsx-style class arrays/objects instead of the class: directive
Spring/Tween classes from svelte/motion instead of the deprecated spring()/tweened() stores
keyed {#each} — never use the index as the key

When unsure of current syntax, do not guess — confirm via the @sveltejs/mcp CLI (see references/tooling.md) and run svelte-autofixer before finalizing any component.

Routing table — READ the matching reference before writing

Task involves…	MANDATORY READ
Runes — `$state`, `$derived`, `$effect`, choosing between them	`references/runes-core.md`
Runes — `$props`, `$bindable`, reactive class fields, `createSubscriber`, `$inspect`	`references/runes-props.md`
Runes — `await` in components, async reactivity, `hydratable`	`references/runes-async.md`
Runes — porting Svelte 4 syntax to runes mode	`references/runes-migration.md`
Runes — reactivity that compiles but behaves wrongly	`references/runes-antipatterns.md`
Template — `{@attach}`, migrating `use:` actions	`references/attachments.md`
Template — `{#snippet}` / `{@render}`, replacing slots	`references/snippets.md`
Template — `{@html}`, `{@const}`, `{@debug}`, keyed each, `bind:`, `<svelte:window>`	`references/template-tags.md`
Components — Bits/Ark/Melt UI, web components, custom elements	`references/component-libraries.md`
Components — forms inside components	`references/forms.md`
Components — CSS from JS, styling children, context	`references/styling-context.md`
Motion — `Spring`, `Tween`, `transition:`, `animate:flip`, easing, `prefersReducedMotion`	`references/motion.md`
Routing — file naming (`+page`/`+layout`/`+error`/`+server`), route groups, params	`references/routing-files.md`
Routing — nested layouts, layout groups, layout data	`references/layouts.md`
Routing — `+error.svelte`, expected vs unexpected errors	`references/error-handling.md`
Routing — `<svelte:boundary>`	`references/error-boundary.md`
Routing — SSR, hydration mismatches, browser-only work	`references/ssr-hydration.md`
Data — `load` functions, server vs universal, `depends`	`references/load-functions.md`
Data — form actions, progressive enhancement	`references/form-actions.md`
Data — `fail()` / `redirect()` / `error()`	`references/errors-redirects.md`
Data — serialization across the boundary, `invalidateAll()`	`references/serialization-invalidation.md`
Remote — `query()` / `form()` in `*.remote.ts`, schema validation	`references/remote-query-form.md`
Remote — `command()`, single-flight mutations, `prerender()`, `getRequestEvent()`	`references/remote-command-prerender.md`
Deploy — adapters, Vite/pnpm build setup	`references/deployment-adapters.md`
Deploy — publishing a Svelte library	`references/library-authoring.md`
Deploy — PWA setup, Cloudflare/streaming gotchas	`references/pwa-and-cloudflare.md`
Tooling — confirming syntax, looking up docs, validating/fixing code	`references/tooling.md`

Read the full file on GitHub · 87 lines

Files

What ships with it

27 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

1mo ago Changed · +6 lines · +46 tokens per session 67341cf5a3e5
1mo ago First seen · 81 lines · 203 tokens per session scan A 179084bfb686

Subscribe to this mod's changes

with-svelte is a skill published in the GitHub repository robcsaszar/frontend-kit (1 stars, last pushed 1mo ago), licensed MIT. It adds 249 tokens to every session and 1,992 once invoked, about $0.0010 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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with-svelte

Getting it into your agent

Wrote this? Show the measurements

What it costs to keep this loaded

Grade A, and why

Nothing flagged

How it starts

with-svelte

Always-on core (every Svelte task)

Routing table — READ the matching reference before writing

What ships with it

What this file has done since we first saw it

Other skills, from other repositories

svelte-expert

shadcn-sveltekit-design

svelte

svelte-docs

svelte-template-directives

sveltekit-remote-functions