---

name: "svelte-code-review" description: "Review a Svelte or SvelteKit change for runes, load and action boundaries, and Kit 2 versus Kit 3 config. Use for a Svelte code review. Do not use for a Svelte 4 pattern pasted into a runes component, or a non-Svelte repository."

Svelte Code Review Skill for Copilot

Copilot skill svelte-code-review for Svelte. The description decides when Copilot loads it. Keep this copy under .github/skills.

When to run

Run this review for a Svelte component, a SvelteKit load or action, or a config change.

When to leave it

Stop for a non-Svelte repository. Do not upgrade Svelte or Kit unless the user asked.

Steps

1. Read the Svelte and Kit majors. On Kit 3, a new svelte.config.js, an import from $app/stores, or a $lib import is a high finding. On Kit 2 those are still valid. Do not flag them there. Svelte 4 syntax in a rune component is a high finding.
2. Search for module-level mutable state in server code. User data stored there is a high finding.
3. Check +page.ts and .svelte files for a server-only import. That is a high finding.
4. Check {@html}, form actions that trust a hidden user id, and $effect loops.
5. Look for a hydration hazard: window or Math.random during init.
6. Run the project's test command only if the user asked. Otherwise write not run.

Output

Findings with severity, file, line, the boundary that broke, and a fix. Include both majors.

## Findings
- high | path:line | what is wrong | what to do instead

## No findings
Say "No findings" and list the files you opened. A search you skipped is not a clean result.

## Example
Input: `src/routes/notes/+page.ts` imports `page` from `$app/state` and reads `page.params.id`.
Output: high | src/routes/notes/+page.ts:1 | a load function cannot read `page` | export `load({ params })` and use `params.id`. In a `.svelte` component, `$app/state` and `$derived` are the right read.

Do not flag the valid pattern named in the standards. Flag the mistake next to it.

Stop

Stop when the user asks you to convert the whole app to runes or to Kit 3 in one review.

Severity

high is a bug a caller can hit or a secret that leaks. medium is a broken contract that needs a specific input. low is a cleanup that does not change behaviour.