mcp: correctly fix authority-less MCP resources cannot be read by VS Code (microsoft#254003)

Closes microsoft#250905

Author: connor4312

src/vs/workbench/contrib/mcp/browser/mcpResourceQuickAccess.ts

@@ -130,7 +130,7 @@ export class McpResourcePickHelper {
 			return uri;
 		}
 
-		this._notificationService.warn(localize('mcp.resource.template.notFound', "The resource {0} was not found.", McpResourceURI.toServer(uri).resourceURI.toString()));
+		this._notificationService.warn(localize('mcp.resource.template.notFound', "The resource {0} was not found.", McpResourceURI.toServer(uri).resourceURL.toString()));
 		return undefined;
 	}
 

src/vs/workbench/contrib/mcp/common/mcpResourceFilesystem.ts

@@ -108,11 +108,11 @@ export class McpResourceFilesystem extends Disposable implements IWorkbenchContr
 			watchedOnHandler = handler;
 
 			const token = callCts.value.token;
-			handler.subscribe({ uri: resourceURI.toString(true) }, token).then(
+			handler.subscribe({ uri: resourceURI.toString() }, token).then(
 				() => {
 					if (!token.isCancellationRequested) {
 						watchListener.value = handler.onDidUpdateResource(e => {
-							if (equalsUriPath(e.params.uri, resourceURI)) {
+							if (equalsUrlPath(e.params.uri, resourceURI)) {
 								this._onDidChangeFile.fire([{ resource: uri, type: FileChangeType.UPDATED }]);
 							}
 						});
@@ -147,7 +147,7 @@ export class McpResourceFilesystem extends Disposable implements IWorkbenchContr
 			throw createFileSystemProviderError(`File is not a directory`, FileSystemProviderErrorCode.FileNotADirectory);
 		}
 
-		const resourcePathParts = resourceURI.path.split('/');
+		const resourcePathParts = resourceURI.pathname.split('/');
 
 		const output = new Map<string, FileType>();
 		for (const content of contents) {
@@ -207,15 +207,15 @@ export class McpResourceFilesystem extends Disposable implements IWorkbenchContr
 
 	private _decodeURI(uri: URI) {
 		let definitionId: string;
-		let resourceURI: URI;
+		let resourceURL: URL;
 		try {
-			({ definitionId, resourceURI } = McpResourceURI.toServer(uri));
+			({ definitionId, resourceURL } = McpResourceURI.toServer(uri));
 		} catch (e) {
 			throw createFileSystemProviderError(String(e), FileSystemProviderErrorCode.FileNotFound);
 		}
 
-		if (resourceURI.path.endsWith('/')) {
-			resourceURI = resourceURI.with({ path: resourceURI.path.slice(0, -1) });
+		if (resourceURL.pathname.endsWith('/')) {
+			resourceURL.pathname = resourceURL.pathname.slice(0, -1);
 		}
 
 		const server = this._mcpService.servers.get().find(s => s.definition.id === definitionId);
@@ -228,25 +228,25 @@ export class McpResourceFilesystem extends Disposable implements IWorkbenchContr
 			throw createFileSystemProviderError(`MCP server ${definitionId} does not support resources`, FileSystemProviderErrorCode.FileNotFound);
 		}
 
-		return { definitionId, resourceURI, server };
+		return { definitionId, resourceURI: resourceURL, server };
 	}
 
 	private async _readURI(uri: URI, token?: CancellationToken) {
 		const { resourceURI, server } = this._decodeURI(uri);
-		const res = await McpServer.callOn(server, r => r.readResource({ uri: resourceURI.toString(true) }, token), token);
+		const res = await McpServer.callOn(server, r => r.readResource({ uri: resourceURI.toString() }, token), token);
 
 		return {
 			contents: res.contents,
 			resourceURI,
-			forSameURI: res.contents.filter(c => equalsUriPath(c.uri, resourceURI)),
+			forSameURI: res.contents.filter(c => equalsUrlPath(c.uri, resourceURI)),
 		};
 	}
 }
 
-function equalsUriPath(a: string, b: URI): boolean {
+function equalsUrlPath(a: string, b: URL): boolean {
 	// MCP doesn't specify either way, but underlying systems may can be case-sensitive.
 	// It's better to treat case-sensitive paths as case-insensitive than vise-versa.
-	return equalsIgnoreCase(URI.parse(a).path, b.path);
+	return equalsIgnoreCase(new URL(a).pathname, b.pathname);
 }
 
 function contentToBuffer(content: MCP.TextResourceContents | MCP.BlobResourceContents): Uint8Array {

src/vs/workbench/contrib/mcp/common/mcpTypes.ts

@@ -678,7 +678,7 @@ export namespace McpResourceURI {
 		});
 	}
 
-	export function toServer(uri: URI | string): { definitionId: string; resourceURI: URI } {
+	export function toServer(uri: URI | string): { definitionId: string; resourceURL: URL } {
 		if (typeof uri === 'string') {
 			uri = URI.parse(uri);
 		}
@@ -690,13 +690,16 @@ export namespace McpResourceURI {
 			throw new Error(`Invalid MCP resource URI: ${uri.toString()}`);
 		}
 		const [, serverScheme, authority, ...path] = parts;
+
+		// URI cannot correctly stringify empty authorities (#250905) so we use URL instead to construct
+		const url = new URL(`${serverScheme}://${authority.toLowerCase() === emptyAuthorityPlaceholder ? '' : authority}`);
+		url.pathname = path.length ? ('/' + path.join('/')) : '';
+		url.search = uri.query;
+		url.hash = uri.fragment;
+
 		return {
 			definitionId: decodeHex(uri.authority).toString(),
-			resourceURI: uri.with({
-				scheme: serverScheme,
-				authority: authority.toLowerCase() === emptyAuthorityPlaceholder ? '' : authority,
-				path: path.length ? ('/' + path.join('/')) : '',
-			}),
+			resourceURL: url,
 		};
 	}
 

src/vs/workbench/contrib/mcp/test/common/mcpTypes.test.ts

@@ -15,13 +15,16 @@ suite('MCP Types', () => {
 			const from = McpResourceURI.fromServer({ label: '', id: 'my-id' }, uri);
 			const to = McpResourceURI.toServer(from);
 			assert.strictEqual(to.definitionId, 'my-id');
-			assert.strictEqual(to.resourceURI.toString(true), uri, `expected to round trip ${uri}`);
+			assert.strictEqual(to.resourceURL.toString(), uri, `expected to round trip ${uri}`);
 		};
 
 		roundTrip('file:///path/to/file.txt');
 		roundTrip('custom-scheme://my-path/to/resource.txt');
 		roundTrip('custom-scheme://my-path');
 		roundTrip('custom-scheme://my-path/');
 		roundTrip('custom-scheme://my-path/?with=query&params=here');
+
+		roundTrip('custom-scheme:///my-path');
+		roundTrip('custom-scheme:///my-path/foo/?with=query&params=here');
 	});
 });