Menu: custom links cannot use relative URLs in admin UI; REST API does not persist custom_url

[ckelly8]

Description

When adding a custom link menu item, relative URLs (e.g., /contact) cannot be saved through the admin UI, and the REST API does not persist the custom_url field at all — even though the seed system and database schema fully support them.

This means the only reliable way to create a custom link menu item with a URL is via emdash seed.

Two related issues

1. Admin UI rejects relative URLs

The "Add Custom Link" dialog at /_emdash/admin/menus/<slug> validates the URL field in a way that rejects relative paths like /contact. Entering /contact and clicking "Add" shows: "Please enter a URL."

Expected: Relative URLs like /contact, /about, /posts should be accepted. These are the most common pattern for internal links and are what the seed system uses.

2. REST API does not persist custom_url

Creating a menu item via POST /_emdash/api/menus/{menu}/items never saves the URL. We tested every plausible field name — all result in custom_url: null:

Field name	Relative URL	Absolute URL	Result
custom_url	/contact	http://localhost:4321/contact	null
url	/contact	http://localhost:4321/contact	null
href	/contact	—	null
link	/contact	—	null

The item is created (label, type, sort_order all save correctly) but the URL is silently dropped.

Evidence that the schema supports relative URLs

Items created via emdash seed store relative URLs correctly in the custom_url column:

{ "type": "custom", "custom_url": "/", "label": "Home" },
{ "type": "custom", "custom_url": "/pages/about", "label": "About" },
{ "type": "custom", "custom_url": "/posts", "label": "Posts" }

These render correctly in the frontend via getMenu().

Steps to reproduce

Admin UI:

1. Navigate to /_emdash/admin/menus/primary
2. Click "Add Custom Link"
3. Enter label: "Contact", URL: /contact
4. Click "Add" → "Please enter a URL."

REST API:

1. POST /_emdash/api/menus/primary/items with body {"type":"custom","label":"Contact","custom_url":"/contact","sort_order":3}
2. Response shows "custom_url": null

Environment

• emdash version: 0.1.1
• Platform: Cloudflare Workers (D1) / local dev via Wrangler
• Template: blog-cloudflare