Headless site URLs are treated as external in URL::tidy()

[lostgeek]

Bug description

In a headless multisite setup, the CMS and public frontend run on different hosts.

Entry permalinks and SEO metadata are generated for the frontend host. For language/site root URLs (e.g. /, /fr), those URLs often include a trailing slash (https://www.example.com/fr/).

We expect Statamic’s default trailing-slash policy (no trailing slash unless URL::enforceTrailingSlashes() is enabled) to apply to those URLs as well.

What actually happens: URL::tidy() leaves them unchanged. Root URLs keep their trailing slash in canonical URLs, hreflang alternates, sitemap entries, etc.

Example:

Field	Value
home_url	https://www.example.com/fr ✅
canonical_url / permalink	https://www.example.com/fr/ ❌

home_url is correct because it comes from Site::absoluteUrl(), which resolves site config properly. Entry permalinks go through URL::tidy() without normalization.

How to reproduce

Setup

1. Configure split hosts:

APP_URL=https://cms.example.com
FRONTEND_URL=https://www.example.com

2. In resources/sites.yaml:

de:
  url: '{{ config.app.frontend_url }}'
fr:
  url: '{{ config.app.frontend_url }}/fr'

3. Create/publish homepage entries for de and fr (URI / on each site).

Steps

1. Open Tinker or a test route on the CMS.
2. Resolve a frontend root URL, e.g. the FR homepage permalink:

use Statamic\Facades\Entry;
use Statamic\Facades\URL;

$entry = Entry::query()->where('site', 'fr')->where('uri', '/')->first();

$permalink = $entry->absoluteUrl(); // e.g. https://www.example.com/fr/

3. Compare tidy behavior:

URL::tidy($permalink);        // https://www.example.com/fr/  ← trailing slash kept
URL::tidy($permalink, true);  // https://www.example.com/fr   ← normalized

Logs

Environment

Environment
Laravel Version: 12.66.0
PHP Version: 8.5.6
Composer Version: 2.10.0
Environment: local
Debug Mode: ENABLED
Maintenance Mode: OFF
Timezone: UTC
Locale: de

Statamic
Addons: 7
License Key: Set
Sites: 3 (🇩🇪 Deutsch, 🇫🇷 Français, 🇬🇧 English)
Stache Watcher: Enabled (auto)
Static Caching: Disabled
Version: 6.27.1 PRO

Statamic Addons
statamic/seo-pro: 7.13.1

Installation

Other (please explain)

Additional details

No response