Lucia Auth v3 is a lightweight, framework-agnostic session management library. It handles session creation, validation, and deletion through database adapters, leaving credential verification to the developer.
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What is the core model that Lucia Auth v3 is built around?
Lucia v3 is fundamentally a session management library. It creates opaque session tokens, stores session data in your database via an adapter, and validates tokens on each request. Lucia is auth-strategy agnostic — it handles sessions, while you implement credential verification (password check, OAuth exchange, etc.) yourself.
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What does createSession(userId, attributes) do in Lucia Auth v3?
createSession() inserts a new session row in the database with a randomly generated session ID, the associated user ID, and an expiry timestamp. It returns a Session object. You then create a session cookie from the session ID using lucia.createSessionCookie(session.id) and set it on the response.
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What does validateSessionToken(token) return in Lucia Auth v3?
validateSessionToken() looks up the session in the database, checks expiry, and returns { session, user }. If the session does not exist or is expired, both fields are null. Lucia also implements session rolling (automatically extending the expiry) within this call when the session is close to expiring.
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What is the role of a database adapter in Lucia Auth v3?
Database adapters in Lucia v3 implement a small interface with methods like getSessionAndUser(), createSession(), and deleteSession(). Official adapters exist for Drizzle, Prisma, and raw SQL databases. Custom adapters can be written for any storage backend by implementing the same interface.
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In Lucia Auth v3, how are session cookies created and read?
Cookie management in Lucia v3 is explicit: createSessionCookie(sessionId) returns an object with name, value, and attributes that you set on the HTTP response yourself. On incoming requests, readSessionCookie(header) extracts the session ID from the Cookie header. This framework-agnostic design works with any server runtime.