migration

migration is a skill for Claude Code from fubits1/svelte-skills. It costs 50 tokens per session (1,682 once invoked), scanned A, original, MIT.

A controlled process for upgrading frameworks, APIs, or major dependencies by comparing the verified code state before and after the change.

In plain words
What is it for?
Use it for framework migrations, major dependency updates, configuration changes, and other work involving breaking changes or version bumps.
Why use it?
It reduces the risk of hidden regressions and prevents misleading comparisons when dependencies were already changed before testing began.

Skill for Claude Code

Written for Claude Code: user-invocable in frontmatter.

Part of the frontend plugin — 13 skills shipped together

Good fit Use it for framework migrations, major dependency updates, configuration changes, and other work involving breaking changes or version bumps.

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

Made for: Claude Code.

Or install frontend, the plugin that ships this one along with the rest of its 13 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.

agentmods badge for migration

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/fubits1/svelte-skills/migration"><img src="https://agentmods.dev/badge/skills/fubits1/svelte-skills/migration.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 50 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,682 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 $0.00050 $0.01682
Opus 5 $0.00025 $0.00841
Sonnet 5 $0.00010 $0.00336
Haiku 4.5 $0.00005 $0.00168

Measured 9d ago against content hash 2acd9f4bf486, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

migration 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 9d 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/frontend/skills/migration/SKILL.md · 171 lines

How it starts

The opening of the file, as written. The whole thing — 171 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Migration

Framework upgrades, major dep bumps, config migrations. The core challenge is proving zero regressions, which requires baselines captured on the TRUE pre-change state.

Rule Zero: Check Working Tree FIRST

Before planning, researching, or writing anything:

git status
git diff package.json

If package.json is already modified, deps may already be upgraded. Baselines taken now reflect post-upgrade state and are WORTHLESS for comparison. You must restore old deps before capturing baselines (see Phase 3a).

If package.json is clean, capture all baselines before touching it.

This is non-negotiable. Baselines on upgraded deps cannot prove zero regressions. Ask yourself: "What state was the code in BEFORE any migration work started?" That is the state you baseline against.

Phase 1: Research

REQUIRED: Use agent:research skill. All four channels, local investigation, docs/MCPs, online research, verify and synthesize.

For each breaking change found in the migration guide, grep the codebase to check if it applies. Don't assume, verify.

Output: A list of concrete changes needed, with file paths and line numbers.

Phase 2: Ask Before Assuming

Do NOT assume version numbers (.nvmrc, TypeScript, etc.), which config blocks to keep or remove, or whether a deprecated pattern should be cleaned up. ASK.

Phase 3: Baseline Capture

3a: Restore Pre-Upgrade State (if deps already changed)

git stash
pnpm install
# verify project builds with OLD deps

3b: Capture Baselines

  1. Build output: full log, page count
  2. Sitemap: copy XML files, extract every <loc> URL to flat list
  3. Screenshot every route: Playwright MCP, every sitemap URL, assert no console errors
  4. Measure page sections: per frontend:pixel-perfect: getBoundingClientRect() on every visible section, save as JSON
  5. Run existing tests: save output, record pass/fail counts

3c: Restore Upgraded State

git stash pop
pnpm install

Read the full file on GitHub · 171 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. 9d ago First seen · 171 lines · 50 tokens per session scan A 2acd9f4bf486

Subscribe to this mod's changes

migration is a skill published in the GitHub repository fubits1/svelte-skills (10 stars, last pushed 1mo ago), licensed MIT. It adds 50 tokens to every session and 1,682 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.

Related

Other skills, from other repositories

systematic-debugging

Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.

obra/superpowers · 21 tokens

local-ai-agents

Build local-first AI agents that run entirely on a developer workstation with Microsoft Foundry Local and Qwen function-calling models. Covers Small Language Models (SLMs), the OpenAI-compatible local endpoint, sandboxed local tools, local RAG with Chroma, local MCP servers, hybrid cloud/local routing, and the…

microsoft/ai-agents-for-beginners · 200 tokens

next-cache-components-adoption

Turn on Cache Components in a Next.js app and resolve the blocking routes it surfaces. Use when the user wants to enable, adopt, or migrate to Cache Components, flip the cacheComponents flag, work through a flood of blocking-prerender / instant validation errors, run the cache-components-instant-false codemod, or…

vercel/next.js · 95 tokens

insight-error-page

Write or audit an insight-kind error page for the Next.js dev overlay. Use when creating a new errors/ .mdx page, auditing an existing one, or checking that a page matches the framework fix cards. Covers page structure, title alignment, FixCard cards with Copy prompt button, code snippets, terminology verification…

vercel/next.js · 83 tokens

next-cache-components-optimizer

Drive a Next.js route to instant navigation by setting up an agentic loop, under Cache Components / PPR, on initial load (hard navigation) and client-side navigation (soft navigation). Encode the goal as a failing @next/playwright instant() e2e and work it to green, one verified route at a time; the shipped test then…

vercel/next.js · 170 tokens

next-partial-prefetching-adoption

Turn on Partial Prefetching in a Next.js app and work through the insights it surfaces. Use when the user wants to enable or adopt Partial Prefetching, flip the partialPrefetching flag, opt routes in with export const prefetch = 'partial', audit Link prefetch={true} behavior, preserve existing prefetched UI with…

vercel/next.js · 103 tokens