Note
DayRelay was written and is maintained by Mainmatter and contributors. We offer consulting, training, and team augmentation for Svelte – check out our website to learn more!
DayRelay is a personalized news aggregation app for collecting, organizing, and reading updates from the sources you choose. It generates focused daily editions, keeps source-level run history, and gives each user control over the feeds and prompts that shape their digest.
Visit dayrelay.ai to learn more.
This project was created for a YouTube series about agentic engineering with Svelte. The series uses DayRelay as a practical example of building a real application with modern SvelteKit, AI-assisted development, durable workflows, sandboxed execution, and production-oriented engineering practices.
Watch the playlist: Agentic Engineering with Svelte.
WHile DayRelay was built almost completely using AI, it was not Vibe Coded. We've reviewed the code thoroughly and set-up all the systems to keep the agent in check.
DayRelay is a SvelteKit application backed by a SQLite-compatible database through Drizzle ORM.
- The UI is built with Svelte 5 and SvelteKit.
- Authenticated app pages live under
src/routes/(authed), including news, editions, sources, source run history, and settings. - Server interactions use SvelteKit remote functions.
- Authentication is handled by Better Auth, with email/password and Google sign-in support.
- The durable generation workflow lives in
src/workflows/generate_daily_edition. It fans out active sources, launches sandboxed source runners, waits for webhook results, records per-source success or failure, and persists the final edition. - Source runners execute in sandbox backends under
src/workflows/generate_daily_edition/sandbox, with support for local Docker and Vercel Sandbox execution. - Observability is wired through Sentry on both client and server paths.
- Tests cover components, server behavior, workflows, and end-to-end flows with Vitest and Playwright.
Copyright © 2026 Mainmatter GmbH (https://mainmatter.com).