Allow non-file URI schemes for Root resources

Implements SEP-1573 to enable Roots with any URI scheme (https://, s3://, git://, etc.)
instead of only file:// URIs. This allows servers to work with remote resources while
maintaining full backward compatibility.

Changes:
- Update RootSchema to accept any URI scheme
- Add tests validating both file:// and https:// URIs

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: Tapan Chugh

src/types.test.ts

@@ -5,7 +5,8 @@ import {
     ContentBlockSchema,
     PromptMessageSchema,
     CallToolResultSchema,
-    CompleteRequestSchema
+    CompleteRequestSchema,
+    RootSchema
 } from './types.js';
 
 describe('Types', () => {
@@ -311,4 +312,34 @@ describe('Types', () => {
             }
         });
     });
+
+    describe('Root', () => {
+        test('should validate roots with file:// URIs', () => {
+            const root = {
+                uri: 'file:///users/test/project',
+                name: 'Test Root'
+            };
+
+            const result = RootSchema.safeParse(root);
+            expect(result.success).toBe(true);
+            if (result.success) {
+                expect(result.data.uri).toBe('file:///users/test/project');
+                expect(result.data.name).toBe('Test Root');
+            }
+        });
+
+        test('should validate roots with non-file URI schemes', () => {
+            const root = {
+                uri: 'https://github.com/owner/repo',
+                name: 'GitHub Repo'
+            };
+
+            const result = RootSchema.safeParse(root);
+            expect(result.success).toBe(true);
+            if (result.success) {
+                expect(result.data.uri).toBe('https://github.com/owner/repo');
+                expect(result.data.name).toBe('GitHub Repo');
+            }
+        });
+    });
 });

src/types.ts

@@ -1365,9 +1365,10 @@ export const CompleteResultSchema = ResultSchema.extend({
 export const RootSchema = z
     .object({
         /**
-         * The URI identifying the root. This *must* start with file:// for now.
+         * The URI identifying the root. Can be any valid URI scheme (e.g., file://, https://, s3://, git://).
+         * Servers should document which URI schemes they support and handle unsupported schemes gracefully.
          */
-        uri: z.string().startsWith('file://'),
+        uri: z.string(),
         /**
          * An optional name for the root.
          */