Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/fubits1/svelte-skillsnpx agentmods add skills/fubits1/svelte-skills/mswWrote 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.
[](https://agentmods.dev/skills/fubits1/svelte-skills/msw)<a href="https://agentmods.dev/skills/fubits1/svelte-skills/msw"><img src="https://agentmods.dev/badge/skills/fubits1/svelte-skills/msw/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.
<a href="https://agentmods.dev/skills/fubits1/svelte-skills/msw"><img src="https://agentmods.dev/badge/skills/fubits1/svelte-skills/msw.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00064 | $0.01899 |
| Opus 5 | $0.00032 | $0.00949 |
| Sonnet 5 | $0.00013 | $0.00380 |
| Haiku 4.5 | $0.00006 | $0.00190 |
Grade A, and why
msw 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 10d 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.
How it starts
The opening of the file, as written. The whole thing — 86 lines — stays where its author put it; the contents beside it link to each section on GitHub.
MSW (Mock Service Worker)
The API lives in the docs, not here. mswjs.io/docs: intercepting requests, mocking responses, browser and node integration, msw init, structuring handlers, runtime overrides, WebSockets, debugging runbook. There is no llms.txt.
This skill carries what those pages do not: where the Svelte and Storybook toolchain contradicts them, and the traps written down nowhere.
Which seam: vi.mock replaces a module, MSW replaces the network. MSW is svelte-5:testing-svelte's "only mock external services" applied to HTTP, so keep the real component, the real fetch, real Request/Response.
Three surfaces, three handler sets
| Surface | Started in | Handler set |
|---|---|---|
| Storybook | mswLoader() in .storybook/preview.ts |
full: every story must be hermetic |
| Vitest browser | setupWorker in a setup file |
narrow: per-test worker.use() |
| Dev app | gated entry import (hooks.client.ts on SvelteKit) |
narrow: only what the backend lacks |
One shared array across all three means dev stops talking to your backend the moment someone adds a catch-all for a story. The rest, including the catch-all failure signature and stateful factories, is in references/handlers.md.
The worker script comes from msw init <dir> --save, into public/ on Vite and static/ on SvelteKit, and Storybook must serve it via staticDirs. When every story fails at once rather than one of them, suspect the worker before the handlers: open /mockServiceWorker.js in the browser, and a 404 or a MIME-type error there means it is not being served (browser integration).
What ships with it
3 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.
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.
- 10d ago First seen · 86 lines · 64 tokens per session scan A 0055d5c74e03
msw is a skill published in the GitHub repository fubits1/svelte-skills (10 stars, last pushed 1mo ago), licensed MIT. It adds 64 tokens to every session and 1,899 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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