Add ChilliCream Url scalar (#56)

Author: glen-84

scalars/contributed/chillicream/url.md

@@ -0,0 +1,115 @@
+# Url — GraphQL Custom Scalar
+
+Author – ChilliCream
+
+Date – 2026-01-05
+
+**License and Copyright**
+
+Copyright © GraphQL contributors. This specification is licensed under
+[OWFa 1.0](https://www.openwebfoundation.org/the-agreements/the-owf-1-0-agreements-granted-claims/owfa-1-0).
+
+# Overview
+
+The `Url` scalar type represents a Uniform Resource Locator (URL) as defined by
+RFC 3986. It is intended for scenarios where a field must contain a valid URL,
+such as links to external resources, API endpoints, image sources, or any
+web-accessible resource.
+
+Unlike the built-in `String` scalar which accepts any text, `Url` provides
+validation to ensure the value conforms to the URL specification.
+
+# Recommended name
+
+The recommended name for this scalar is `Url`.
+
+# Result spec
+
+A `Url` scalar must serialize to a string representation of a valid URL
+conforming to RFC 3986.
+
+A valid URL must include:
+
+- A scheme (e.g., `http`, `https`, `ftp`)
+- A hierarchical part (authority and/or path)
+
+The URL may optionally include:
+
+- A query string
+- A fragment identifier
+
+## Examples
+
+These are valid result values:
+
+| Value                                      | Explanation                     |
+| ------------------------------------------ | ------------------------------- |
+| `"https://example.com"`                    | Simple HTTPS URL.               |
+| `"https://example.com/path/to/resource"`   | URL with path.                  |
+| `"https://example.com:8080/api?key=value"` | URL with port and query string. |
+| `"ftp://files.example.com/document.pdf"`   | FTP URL.                        |
+| `"https://example.com/page#section"`       | URL with fragment.              |
+
+These are invalid result values:
+
+| Value             | Why is it invalid                  |
+| ----------------- | ---------------------------------- |
+| `"not a url"`     | Missing scheme and invalid format. |
+| `"//example.com"` | Missing scheme.                    |
+| `"http://"`       | Missing authority/path.            |
+| `"example.com"`   | Missing scheme.                    |
+| `123`             | Must be a string, not a number.    |
+
+# Input spec
+
+A `Url` scalar accepts string values representing valid URLs conforming to RFC
+3986, both as GraphQL literals and as JSON input values.
+
+Implementations should validate:
+
+- String is a valid URL per RFC 3986
+- URL includes a scheme
+- URL has a valid hierarchical structure
+
+## Examples
+
+Valid input values:
+
+GraphQL Literal:
+
+```graphql
+mutation {
+  addBookmark(url: "https://example.com/article") {
+    id
+  }
+}
+```
+
+JSON input:
+
+```json
+{
+  "url": "https://example.com/article"
+}
+```
+
+```json
+{
+  "imageSource": "https://cdn.example.com/images/photo.jpg"
+}
+```
+
+Invalid input values:
+
+| Value             | Why is it invalid                  |
+| ----------------- | ---------------------------------- |
+| `"not a url"`     | Missing scheme and invalid format. |
+| `"//example.com"` | Missing scheme.                    |
+| `"example.com"`   | Missing scheme.                    |
+| `"http://"`       | Missing authority/path.            |
+| `""`              | Empty string.                      |
+
+# References
+
+- [RFC 3986](https://www.rfc-editor.org/rfc/rfc3986) — Uniform Resource
+  Identifier (URI): Generic Syntax