Add ChilliCream URI scalar (#64)

Author: glen-84

scalars/contributed/chillicream/uri.md

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+# URI — GraphQL Custom Scalar
+
+Author – ChilliCream
+
+Date – 2026-02-16
+
+**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 `URI` scalar type represents a Uniform Resource Identifier (URI) as defined
+by RFC 3986. It is intended for scenarios where a field must contain a valid
+URI, which includes both URLs (locators) and URNs (names), such as resource
+identifiers, namespace identifiers, or any standardized resource reference.
+
+Unlike the `URL` scalar which specifically requires a locator with a scheme and
+hierarchical structure, `URI` accepts the broader set of URI formats including
+relative references and URNs. Unlike the built-in `String` scalar which accepts
+any text, `URI` provides validation to ensure the value conforms to the URI
+specification.
+
+# Recommended name
+
+The recommended name for this scalar is `URI`.
+
+# Result spec
+
+A `URI` scalar must serialize to a string representation of a valid URI
+conforming to RFC 3986.
+
+A valid URI may be:
+
+- An absolute URI with scheme (e.g., `https://example.com`,
+  `urn:isbn:0451450523`)
+- A relative reference (e.g., `/path/to/resource`, `../parent/resource`)
+- A URI with optional authority, path, query, and fragment components
+
+## Examples
+
+These are valid result values:
+
+| Value                                      | Explanation                       |
+| ------------------------------------------ | --------------------------------- |
+| `"https://example.com"`                    | Absolute HTTP URL.                |
+| `"urn:isbn:0451450523"`                    | URN for an ISBN.                  |
+| `"/path/to/resource"`                      | Relative reference with path.     |
+| `"//example.com/path"`                     | Protocol-relative reference.      |
+| `"../parent/resource"`                     | Relative reference with parent.   |
+| `"https://example.com:8080/api?key=value"` | Absolute URL with port and query. |
+| `"mailto:user@example.com"`                | Mailto URI.                       |
+| `"#section"`                               | Fragment-only reference.          |
+| `"?query=value"`                           | Query-only reference.             |
+
+These are invalid result values:
+
+| Value                   | Why is it invalid               |
+| ----------------------- | ------------------------------- |
+| `"ht!tp://example.com"` | Invalid scheme characters.      |
+| `"http://exam ple.com"` | Contains whitespace.            |
+| `123`                   | Must be a string, not a number. |
+
+# Input spec
+
+A `URI` scalar accepts string values representing valid URIs conforming to RFC
+3986, both as GraphQL literals and as JSON input values.
+
+Implementations should validate:
+
+- String is a valid URI per RFC 3986
+- String does not contain invalid characters (e.g., unescaped spaces)
+- String follows proper URI syntax rules
+
+Note: Unlike the `URL` scalar, `URI` accepts both absolute and relative
+references, making it suitable for a broader range of use cases.
+
+## Examples
+
+Valid input values:
+
+GraphQL Literal:
+
+```graphql
+mutation {
+  createResource(uri: "urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6") {
+    id
+  }
+}
+```
+
+```graphql
+mutation {
+  addLink(uri: "/relative/path/to/resource") {
+    id
+  }
+}
+```
+
+JSON input:
+
+```json
+{
+  "uri": "https://example.com/article"
+}
+```
+
+```json
+{
+  "resourceId": "urn:isbn:0451450523"
+}
+```
+
+```json
+{
+  "relativeUrl": "../parent/page"
+}
+```
+
+Invalid input values:
+
+| Value                   | Why is it invalid              |
+| ----------------------- | ------------------------------ |
+| `"ht!tp://example.com"` | Invalid scheme characters.     |
+| `"http://exam ple.com"` | Contains unescaped whitespace. |
+| `""`                    | Empty string.                  |
+
+# References
+
+- [RFC 3986](https://www.rfc-editor.org/rfc/rfc3986) — Uniform Resource
+  Identifier (URI): Generic Syntax