feat(genkit-tools/cli): Support cursor config (#3397)

Author: ssbushi

genkit-tools/cli/src/commands/init-ai-tools/ai-tools/cursor.ts

@@ -0,0 +1,108 @@
+/**
+ * Copyright 2025 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { existsSync, readFileSync } from 'fs';
+import { mkdir, writeFile } from 'fs/promises';
+import * as path from 'path';
+import { AIToolConfigResult, AIToolModule, InitConfigOptions } from '../types';
+import {
+  GENKIT_PROMPT_PATH,
+  getGenkitContext,
+  initOrReplaceFile,
+} from '../utils';
+
+const CURSOR_MCP_PATH = path.join('.cursor', 'mcp.json');
+const CURSOR_RULES_DIR = '.cursor/rules';
+const GENKIT_MDC_PATH = path.join(CURSOR_RULES_DIR, 'GENKIT.mdc');
+
+const CURSOR_RULES_HEADER = `---
+description: Genkit project development guidelines
+---
+`;
+
+export const cursor: AIToolModule = {
+  name: 'cursor',
+  displayName: 'Cursor',
+
+  /**
+   * Configures Cursor with Genkit context files.
+   *
+   * This function sets up the necessary files for Cursor to understand the
+   * Genkit app and interact with Genkit MCP tools. It creates
+   * a `.cursor` directory with the following:
+   *
+   * - `mcp.json`: Configures the Genkit MCP server for direct Genkit operations from Cursor.
+   * - `rules/GENKIT.mdc`: The main entry point for project-specific context, importing the base GENKIT.md file.
+   *
+   * File ownership:
+   * - .cursor/mcp.json: Merges with existing config (preserves user settings)
+   * - .cursor/rules/GENKIT.mdc: Fully managed by us (replaced on each update)
+
+   */
+  async configure(options?: InitConfigOptions): Promise<AIToolConfigResult> {
+    const files: AIToolConfigResult['files'] = [];
+
+    // Create the base GENKIT context file (GENKIT.md).
+    // This file contains fundamental details about the GENKIT project.
+    const genkitContext = getGenkitContext();
+    const baseResult = await initOrReplaceFile(
+      GENKIT_PROMPT_PATH,
+      genkitContext
+    );
+    files.push({ path: GENKIT_PROMPT_PATH, updated: baseResult.updated });
+
+    // Handle MCP configuration - merge with existing if present.
+    // This allows Cursor to communicate with Genkit tools.
+    let mcpUpdated = false;
+    let existingConfig: any = {};
+
+    try {
+      const fileExists = existsSync(CURSOR_MCP_PATH);
+      if (fileExists) {
+        existingConfig = JSON.parse(readFileSync(CURSOR_MCP_PATH, 'utf-8'));
+      } else {
+        await mkdir('.cursor', { recursive: true });
+      }
+    } catch (e) {
+      // File doesn't exist or is invalid JSON, start fresh
+    }
+
+    if (!existingConfig.mcpServers?.genkit) {
+      if (!existingConfig.mcpServers) {
+        existingConfig.mcpServers = {};
+      }
+      existingConfig.mcpServers.genkit = {
+        command: 'npx',
+        args: ['genkit', 'mcp'],
+      };
+      await writeFile(CURSOR_MCP_PATH, JSON.stringify(existingConfig, null, 2));
+      mcpUpdated = true;
+    }
+    files.push({ path: CURSOR_MCP_PATH, updated: mcpUpdated });
+
+    // Create the main `GENKIT.mdc` file, which acts as an entry point
+    // for Cursor's AI and imports the other context files.
+    await mkdir(path.join('.cursor', 'rules'), { recursive: true });
+    const genkitImport = '@' + path.join('..', '..', GENKIT_PROMPT_PATH);
+    const importContent = `# Genkit Context\n\n${genkitImport}\n`;
+
+    const mdcContent = CURSOR_RULES_HEADER + '\n' + importContent;
+    const { updated } = await initOrReplaceFile(GENKIT_MDC_PATH, mdcContent);
+    files.push({ path: GENKIT_MDC_PATH, updated: updated });
+
+    return { files };
+  },
+};

genkit-tools/cli/src/commands/init-ai-tools/command.ts

@@ -19,6 +19,7 @@ import { checkbox } from '@inquirer/prompts';
 import * as clc from 'colorette';
 import { Command } from 'commander';
 import { claude } from './ai-tools/claude';
+import { cursor } from './ai-tools/cursor';
 import { gemini } from './ai-tools/gemini';
 import { generic } from './ai-tools/generic';
 import { AIToolChoice, AIToolModule, InitConfigOptions } from './types';
@@ -28,6 +29,7 @@ import { AIToolChoice, AIToolModule, InitConfigOptions } from './types';
 export const AI_TOOLS: Record<string, AIToolModule> = {
   gemini,
   claude,
+  cursor,
   generic,
 };