Add dynamic local schema detection for SourceKit-LSP

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## {{releaseVersion}} - {{releaseDate}}
 
+### Added
+
+- When editing .sourcekit-lsp/config.json use the JSON schema from the toolchain ([#1979](https://github.com/swiftlang/vscode-swift/pull/1979))
+
 ### Fixed
 
 - Fix extension failing to activate when Swiftly was installed via Homebrew ([#1975](https://github.com/swiftlang/vscode-swift/pull/1975))

src/WorkspaceContext.ts

@@ -28,6 +28,7 @@ import { CommentCompletionProviders } from "./editor/CommentCompletion";
 import { SwiftLogger } from "./logging/SwiftLogger";
 import { SwiftLoggerFactory } from "./logging/SwiftLoggerFactory";
 import { LanguageClientToolchainCoordinator } from "./sourcekit-lsp/LanguageClientToolchainCoordinator";
+import { SourcekitSchemaRegistry } from "./sourcekit-lsp/SourcekitSchemaRegistry";
 import { DocCDocumentationRequest, ReIndexProjectRequest } from "./sourcekit-lsp/extensions";
 import { SwiftPluginTaskProvider } from "./tasks/SwiftPluginTaskProvider";
 import { SwiftTaskProvider } from "./tasks/SwiftTaskProvider";
@@ -62,6 +63,7 @@ export class WorkspaceContext implements vscode.Disposable {
     public documentation: DocumentationManager;
     public testRunManager: TestRunManager;
     public projectPanel: ProjectPanelProvider;
+    private sourcekitSchemaRegistry: SourcekitSchemaRegistry;
     private lastFocusUri: vscode.Uri | undefined;
     private initialisationFinished = false;
 
@@ -105,6 +107,7 @@ export class WorkspaceContext implements vscode.Disposable {
         this.currentDocument = null;
         this.commentCompletionProvider = new CommentCompletionProviders();
         this.projectPanel = new ProjectPanelProvider(this);
+        this.sourcekitSchemaRegistry = new SourcekitSchemaRegistry(this);
 
         const onChangeConfig = vscode.workspace.onDidChangeConfiguration(async event => {
             // Clear build path cache when build-related configurations change
@@ -229,6 +232,7 @@ export class WorkspaceContext implements vscode.Disposable {
             this.statusItem,
             this.buildStatus,
             this.projectPanel,
+            this.sourcekitSchemaRegistry.register(),
         ];
         this.lastFocusUri = vscode.window.activeTextEditor?.document.uri;
 
@@ -244,6 +248,7 @@ export class WorkspaceContext implements vscode.Disposable {
     }
 
     dispose() {
+        this.sourcekitSchemaRegistry.dispose();
         this.folders.forEach(f => f.dispose());
         this.folders.length = 0;
         this.subscriptions.forEach(item => item.dispose());

src/commands/generateSourcekitConfiguration.ts

@@ -18,10 +18,11 @@ import { FolderContext } from "../FolderContext";
 import { WorkspaceContext } from "../WorkspaceContext";
 import configuration from "../configuration";
 import { selectFolder } from "../ui/SelectFolderQuickPick";
+import { fileExists } from "../utilities/filesystem";
 import restartLSPServer from "./restartLSPServer";
 
-export const sourcekitDotFolder: string = ".sourcekit-lsp";
-export const sourcekitConfigFileName: string = "config.json";
+const sourcekitDotFolder: string = ".sourcekit-lsp";
+const sourcekitConfigFileName: string = "config.json";
 
 export async function generateSourcekitConfiguration(ctx: WorkspaceContext): Promise<boolean> {
     if (ctx.folders.length === 0) {
@@ -128,6 +129,13 @@ async function checkURLExists(url: string): Promise<boolean> {
 }
 
 export async function determineSchemaURL(folderContext: FolderContext): Promise<string> {
+    // Check if local schema exists first
+    if (await hasLocalSchema(folderContext)) {
+        const localPath = localSchemaPath(folderContext);
+        return vscode.Uri.file(localPath).toString();
+    }
+
+    // Fall back to remote URL for older toolchains
     const version = folderContext.toolchain.swiftVersion;
     const versionString = `${version.major}.${version.minor}`;
     let branch =
@@ -138,6 +146,26 @@ export async function determineSchemaURL(folderContext: FolderContext): Promise<
     return schemaURL(branch);
 }
 
+/**
+ * Returns the path to the local sourcekit-lsp schema file in the toolchain.
+ * This file only exists in newer toolchains (approximately Swift 6.3+).
+ */
+export function localSchemaPath(folderContext: FolderContext): string {
+    return join(
+        folderContext.toolchain.toolchainPath,
+        "share",
+        "sourcekit-lsp",
+        "config.schema.json"
+    );
+}
+
+/**
+ * Checks if the local schema file exists in the toolchain.
+ */
+export async function hasLocalSchema(folderContext: FolderContext): Promise<boolean> {
+    return await fileExists(localSchemaPath(folderContext));
+}
+
 async function getValidatedFolderContext(
     uri: vscode.Uri,
     workspaceContext: WorkspaceContext

src/sourcekit-lsp/SourcekitSchemaRegistry.ts

@@ -0,0 +1,91 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the VS Code Swift open source project
+//
+// Copyright (c) 2025 the VS Code Swift project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of VS Code Swift project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+import * as vscode from "vscode";
+
+import { FolderContext } from "../FolderContext";
+import { WorkspaceContext } from "../WorkspaceContext";
+import {
+    determineSchemaURL,
+    sourcekitConfigFilePath,
+} from "../commands/generateSourcekitConfiguration";
+
+/**
+ * Manages dynamic JSON schema associations for sourcekit-lsp config files.
+ * This allows VS Code to provide validation and IntelliSense using the
+ * appropriate schema (local or remote) based on the toolchain.
+ */
+export class SourcekitSchemaRegistry {
+    private disposables: vscode.Disposable[] = [];
+
+    constructor(private workspaceContext: WorkspaceContext) {}
+
+    /**
+     * Registers event handlers to dynamically configure JSON schemas
+     * for sourcekit-lsp config documents.
+     */
+    register(): vscode.Disposable {
+        // Handle documents that are already open
+        vscode.workspace.textDocuments.forEach(doc => {
+            void this.configureSchemaForDocument(doc);
+        });
+
+        // Handle newly opened documents
+        const onDidOpenDisposable = vscode.workspace.onDidOpenTextDocument(doc => {
+            void this.configureSchemaForDocument(doc);
+        });
+
+        this.disposables.push(onDidOpenDisposable);
+
+        return vscode.Disposable.from(...this.disposables);
+    }
+
+    /**
+     * Configures the JSON schema for a document if it's a sourcekit-lsp config file.
+     */
+    private async configureSchemaForDocument(document: vscode.TextDocument): Promise<void> {
+        if (document.languageId !== "json") {
+            return;
+        }
+
+        const folderContext = await this.getFolderContextForDocument(document);
+        if (!folderContext) {
+            return;
+        }
+
+        const schemaUrl = await determineSchemaURL(folderContext);
+
+        // Use VS Code's JSON language configuration API to associate the schema
+        await vscode.commands.executeCommand("json.setSchema", document.uri.toString(), schemaUrl);
+    }
+
+    /**
+     * Gets the FolderContext for a document if it's a sourcekit-lsp config file.
+     */
+    private async getFolderContextForDocument(
+        document: vscode.TextDocument
+    ): Promise<FolderContext | null> {
+        for (const folderContext of this.workspaceContext.folders) {
+            const configPath = sourcekitConfigFilePath(folderContext);
+            if (document.uri.fsPath === configPath) {
+                return folderContext;
+            }
+        }
+        return null;
+    }
+
+    dispose() {
+        this.disposables.forEach(d => d.dispose());
+        this.disposables = [];
+    }
+}