# Authentication

> Sessions, sign-in/sign-up flows, OAuth, magic links, or organization context on the session.

- Skill: `latitude-dev/authentication` (Agent Skill)
- Install (CLI): `npx skillmds@latest add latitude-dev/authentication`
- Raw SKILL.md: https://api.skillmd.com/api/skills/latitude-dev/authentication/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Integrations & APIs
- Author: latitude-dev (https://skillmd.com/u/latitude-dev)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/latitude-dev/authentication

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# Authentication (Better Auth)

**When to use:** Sessions, sign-in/sign-up flows, OAuth, magic links, or organization context on the session.

## Stack

- **`@platform/db-postgres`** exposes **`createBetterAuth()`** in `packages/platform/db-postgres/src/create-better-auth.ts`, wiring **better-auth** with the Drizzle adapter against the shared Postgres client.
- Sessions: `auth.api.getSession({ headers })` → `{ user, session }` with typed fields.
- **`User`** includes `id`, `email`, `name` — use those fields directly (no assertions).

## Web app helpers

- Session helpers: `apps/web/src/domains/sessions/session.functions.ts` (`getSession`, `ensureSession`, etc.).
- **Organization context** is added via the **`customSession`** plugin (multi-tenant product behavior).

## Domain alignment

- Auth **intent** flows (login/signup completion) use use-cases from **`@domain/auth`** composed with Postgres repositories — keep policy in domain, wiring in apps.

For HTTP boundary rules (who may call what), see [architecture-boundaries](../architecture-boundaries/SKILL.md).