migration-svelte-5

migration-svelte-5 is a skill for Claude Code from fubits1/svelte-skills. It costs 65 tokens per session (3,184 once invoked), scanned A, original, MIT.

A migration guide and workflow for updating Svelte 3 or 4 components to Svelte 5. Svelte is a framework for building web interfaces.

In plain words
What is it for?
Use it when converting Svelte files to runes, Svelte 5's newer programming model, while checking compatibility with older components.
Why use it?
It helps identify syntax and behavior changes, including reactive code, component properties, events, and slots, during an upgrade.

Skill for Claude Code

Written for Claude Code: user-invocable in frontmatter. Also seen: mentions subagents.

Part of the svelte-5-migration plugin — 1 skill shipped together

Good fit Use it when converting Svelte files to runes, Svelte 5's newer programming model, while checking compatibility with older components.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/fubits1/svelte-skills/migration-svelte-5
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 fubits1/svelte-skills --skill migration-svelte-5
Clone the repo
git clone --depth 1 https://github.com/fubits1/svelte-skills

Made for: Claude Code.

Or install svelte-5-migration, the plugin that ships this one along with the rest of its 1 skill.

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.

agentmods badge for migration-svelte-5

README.md
[![agentmods](https://agentmods.dev/badge/skills/fubits1/svelte-skills/migration-svelte-5/github.svg)](https://agentmods.dev/skills/fubits1/svelte-skills/migration-svelte-5)
Your own site
<a href="https://agentmods.dev/skills/fubits1/svelte-skills/migration-svelte-5"><img src="https://agentmods.dev/badge/skills/fubits1/svelte-skills/migration-svelte-5/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.

agentmods 80×15 button for migration-svelte-5

Your own site · 80×15
<a href="https://agentmods.dev/skills/fubits1/svelte-skills/migration-svelte-5"><img src="https://agentmods.dev/badge/skills/fubits1/svelte-skills/migration-svelte-5.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 65 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,184 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00065 $0.03184
Opus 5 $0.00032 $0.01592
Sonnet 5 $0.00013 $0.00637
Haiku 4.5 $0.00006 $0.00318

Measured 11d ago against content hash 1fe4874f518a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

migration-svelte-5 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 11d 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.

plugins/svelte-5-migration/skills/migration-svelte-5/SKILL.md · 311 lines

How it starts

The opening of the file, as written. The whole thing — 311 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Svelte 3/4 to 5 Migration

Authoritative reference: the official Svelte 5 migration guide is the canonical list of breaking changes and gotchas (components are no longer classes → mount/hydrate; $effect is client-only; event-modifier limits; and the rest). This skill is the migration WORKFLOW — order, audit, interop, traps; defer to the guide for the full what-changed.

Required companion skills

Invoke these at the indicated points. This skill says WHEN; they say HOW.

Skill When Source
svelte:svelte-code-writer Before writing/editing ANY .svelte or .svelte.ts plugin: svelte/svelte
svelte:svelte-core-bestpractices Before writing ANY Svelte 5 component logic plugin: svelte/svelte
svelte-5:code-style-svelte After every .svelte file edit this marketplace
frontend:code-style After every file edit this marketplace
frontend:editing During every code edit this marketplace
svelte-5:doc-component After creating or migrating a .svelte component this marketplace
svelte-5:storybook When creating/updating stories this marketplace
svelte-5:storybook-vitest When writing play functions this marketplace
svelte-5:testing-svelte When writing vitest browser tests this marketplace
frontend:playwright Before AND after migration (baselines + verification) this marketplace
frontend:pixel-perfect For any CSS/layout changes during migration this marketplace
frontend:validate-file After EVERY file edit this marketplace
frontend:migration Framework-agnostic phases this skill builds on this marketplace

Prefer delegating each .svelte create/edit/review to the svelte:svelte-file-editor subagent (plugin svelte/svelte). It runs in its own context window, so its docs lookup and autofixer iteration don't spend the main agent's context during a long migration. The companion skills above still say WHEN; the subagent is where the per-file edit happens.

Read the full file on GitHub · 311 lines

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.

  1. 11d ago First seen · 311 lines · 65 tokens per session scan A 1fe4874f518a

Subscribe to this mod's changes

migration-svelte-5 is a skill published in the GitHub repository fubits1/svelte-skills (10 stars, last pushed 1mo ago), licensed MIT. It adds 65 tokens to every session and 3,184 once invoked, about $0.0003 per session on Opus 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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