Add svelte kit routing provider

[gingerbenw]

Goal

Support instrumentation of route change spans when using SvelteKit

Design

By using the available hooks from SvelteKit for beforeNavigate and afterNavigate we can directly read the /[route] instead of an absolute URL, meaning the resolveRoute method simply needs to convert it to a string. As users never interact with resolveRoute this implementation should work for this case.

Changeset

Added a new svelte-kit-performance library which exports a SvelteKitRoutingProvider

Testing

Added unit tests
Added end to end tests matching coverage with vue-router, etc

[github-actions]

Browser bundle size

NPM build

	Package
Before	217.95 kB
After	218.13 kB
±	+182 bytes ⚠️

CDN build

	Unminified	Minfied	Minified + gzipped
Before	110.02 kB	41.96 kB	12.27 kB
After	110.04 kB	41.99 kB	12.28 kB
±	+22 bytes ⚠️	+27 bytes ⚠️	+10 bytes ⚠️

Code coverage

Ok	File (✨=New File)	Lines	Branches	Functions	Statements
🔴	/home/runner/work/bugsnag-js-performance/bugsnag-js-performance/packages/platforms/browser/lib/index.ts	100% (+0%)	100% (+0%)	50% (-16.66%)	100% (+0%)
🔴	✨ /home/runner/work/bugsnag-js-performance/bugsnag-js-performance/packages/svelte-kit/lib/index.ts	0% (+0%)	100% (+100%)	0% (+0%)	0% (+0%)
🔴	✨ /home/runner/work/bugsnag-js-performance/bugsnag-js-performance/packages/svelte-kit/lib/svelte-kit-routing-provider.ts	75% (+75%)	61.53% (+61.53%)	66.66% (+66.66%)	75% (+75%)

Total:

Lines	Branches	Functions	Statements
83.25%(-0.08%)	60.2%(+0.01%)	74.25%(-0.22%)	79.59%(-0.05%)

Generated against c0284d3 on 10 June 2025 at 16:40:15 UTC

[Copilot]

Pull Request Overview

Adds a new SvelteKit routing provider for Bugsnag performance to instrument route-change spans in SvelteKit apps, along with fixtures and tests.

• Introduces @bugsnag/svelte-kit-performance package and SvelteKitRoutingProvider implementation
• Adds unit tests for the routing provider and browser fixtures for end-to-end scenarios
• Updates build configs, TypeScript settings, and project metadata (package.json, CHANGELOG)

Reviewed Changes

Copilot reviewed 31 out of 31 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
test/browser/features/fixtures/packages/svelte-kit/src/routes/contact/+page.svelte	Add contact page fixture
test/browser/features/fixtures/packages/svelte-kit/src/routes/+page.svelte	Add home page fixture
test/browser/features/fixtures/packages/svelte-kit/src/routes/+layout.svelte	Add layout that initializes BugsnagPerformance
test/browser/features/fixtures/packages/svelte-kit/src/routes/+layout.js	Add prerender setting and load function
test/browser/features/fixtures/packages/svelte-kit/src/lib/index.js	Placeholder lib folder
test/browser/features/fixtures/packages/svelte-kit/src/app.html	SvelteKit app HTML template
test/browser/features/fixtures/packages/svelte-kit/src/200.html	Static 200.html fallback page
test/browser/features/fixtures/packages/svelte-kit/package.json	SvelteKit fixture package metadata
test/browser/features/fixtures/packages/svelte-kit/jsconfig.json	JS config for SvelteKit
test/browser/features/fixtures/packages/svelte-kit/.npmrc	Enforce engine-strict
test/browser/features/fixtures/packages/svelte-kit/.gitignore	Git ignore for SvelteKit fixture
packages/svelte-kit/tsconfig.json	TS config for the routing provider package
packages/svelte-kit/tests/svelte-kit-routing-provider.test.ts	Unit tests for SvelteKitRoutingProvider
packages/svelte-kit/rollup.config.mjs	Rollup build configuration
packages/svelte-kit/package.json	@bugsnag/svelte-kit-performance package metadata
packages/svelte-kit/lib/svelte-kit-routing-provider.ts	Implementation of the routing provider
packages/svelte-kit/lib/index.ts	Exports the routing provider
packages/svelte-kit/README.md	Documentation and usage example
packages/svelte-kit/.gitignore	Git ignore for the routing provider package
CHANGELOG.md	Changelog entry for the new routing provider

[gingerbenw]

Sorry @yousif-bugsnag - last one, I promise!