> ## Documentation Index > Fetch the complete documentation index at: https://docs.encoreos.io/llms.txt > Use this file to discover all available pages before exploring further. # Canonical Host Policy > This document defines how canonical URLs and host canonicalization work for the Encore Health OS platform. It is part of the broader Multi-Tenant Host & URL St… This document defines how canonical URLs and host canonicalization work for the Encore Health OS platform. It is part of the broader [Multi-Tenant Host & URL Strategy (PF-81)](../../specs/pf/specs/PF-81-multi-tenant-host-url-strategy.md). ## In-app canonical URLs (PF-74) * **Slug URLs are canonical.** When a user accesses `/o/:orgSlug/...`, the app resolves the organization, sets context, and renders the requested page in place. The URL is not changed to a flat path (e.g. `/hr/employees`). This preserves shareable links, browser history, and deep-link stability. * **Flat routes** (e.g. `/hr/employees`) remain supported for backward compatibility. They do not redirect to slug URLs by default. Components that generate internal links should prefer `useOrgPath()` or `orgPath(slug, path)` so that users who arrived via a slug URL stay in slug space. ## Host canonicalization (PF-77) When the platform or a tenant uses a custom domain, one canonical host should be chosen to avoid duplicate content and inconsistent session behavior. ### Apex vs `www` * **Choose one canonical host per deployment:** either the apex domain (e.g. `app.encoreos.io`) or the `www` variant (e.g. `www.app.encoreos.io`), not both. * **Configure redirects** so that the non-canonical host redirects (301/308) to the canonical host. This is typically done in the **Vercel project β†’ Settings β†’ Domains** (add both apex and `www`, then set a domain redirect from the non-canonical to the canonical). Alternatively, use [Vercel redirects](https://vercel.com/docs/redirects) in `vercel.json` or in the dashboard when the same project serves both hosts. * **Cookie scope:** Ensure session cookies are set on the canonical host (or with a shared parent domain) so that redirects between apex and `www` do not drop the session. ### Subdomain vs custom domain (multi-tenant) * If both a platform subdomain (e.g. `tenant.platform.com`) and a tenant custom domain (e.g. `app.tenant.com`) serve the same tenant, either: * **Redirect** one to the other (e.g. redirect subdomain to custom domain), or * **Set a canonical URL** in the HTML `` (e.g. ``) to indicate the official URL and avoid search-engine duplicate content. * Path-based org routing (PF-74) uses `/o/:orgSlug/...`; host canonicalization is relevant when custom domains (PF-77) are in use. ## References * [PF-81 Multi-Tenant Host & URL Strategy](../../specs/pf/specs/PF-81-multi-tenant-host-url-strategy.md) β€” overview of path routing, custom domains, and canonical host * [PF-74 Organization URL Routing](../../specs/pf/specs/PF-74-organization-url-routing.md) * [PF-77 Tenant Domain Management](../../specs/pf/specs/PF-77-tenant-domain-management.md) * [Vercel Deployment (build/ignore settings)](./vercel-deployment.md) * [Vercel: Domain management for multi-tenant](https://vercel.com/docs/multi-tenant/domain-management) * [Vercel: Redirects](https://vercel.com/docs/redirects)