Playwright MCP Server

Instructions

Implementation Reference

• src/tools/codegen/index.ts:25-80 (handler)

  Core implementation of the start_codegen_session tool. Defines the Tool object including name, description, input parameters schema, and the async handler function that merges options, ensures output directory, starts ActionRecorder session, and returns session details.

  export const startCodegenSession: Tool = {
    name: 'start_codegen_session',
    description: 'Start a new code generation session to record MCP tool actions',
    parameters: {
      type: 'object',
      properties: {
        options: {
          type: 'object',
          description: 'Code generation options',
          properties: {
            outputPath: { type: 'string' },
            testNamePrefix: { type: 'string' },
            includeComments: { type: 'boolean' }
          }
        }
      }
    },
    handler: async ({ options = {} }: { options?: CodegenOptions }) => {
      try {
        // Merge provided options with defaults
        const mergedOptions = { ...DEFAULT_OPTIONS, ...options };
        
        // Ensure output path is absolute and normalized
        const workspaceRoot = getWorkspaceRoot();
        const outputPath = path.isAbsolute(mergedOptions.outputPath) 
          ? mergedOptions.outputPath 
          : path.join(workspaceRoot, mergedOptions.outputPath);
        
        mergedOptions.outputPath = outputPath;
        
        // Ensure output directory exists
        try {
          await fs.mkdir(outputPath, { recursive: true });
        } catch (mkdirError: any) {
          throw new Error(`Failed to create output directory: ${mkdirError.message}`);
        }
        
        const sessionId = ActionRecorder.getInstance().startSession();
        
        // Store options with the session
        const recorder = ActionRecorder.getInstance();
        const session = recorder.getSession(sessionId);
        if (session) {
          session.options = mergedOptions;
        }
        
        return { 
          sessionId,
          options: mergedOptions,
          message: `Started codegen session. Tests will be generated in: ${outputPath}`
        };
      } catch (error: any) {
        throw new Error(`Failed to start codegen session: ${error.message}`);
      }
    }
  };

• src/toolHandler.ts:364-373 (registration)

  Registers and dispatches the start_codegen_session tool call in the main handleToolCall function by invoking its handler via handleCodegenResult. Imports the tool at lines 7-12.

  switch (name) {
    case 'start_codegen_session':
      return await handleCodegenResult(startCodegenSession.handler(args));
    case 'end_codegen_session':
      return await handleCodegenResult(endCodegenSession.handler(args));
    case 'get_codegen_session':
      return await handleCodegenResult(getCodegenSession.handler(args));
    case 'clear_codegen_session':
      return await handleCodegenResult(clearCodegenSession.handler(args));
  }

• src/tools.ts:7-35 (schema)

  Defines the input schema for the start_codegen_session tool in createToolDefinitions(), used for MCP protocol tool definitions. Note: slightly stricter than the implementation schema (requires outputPath).

  {
    name: "start_codegen_session",
    description: "Start a new code generation session to record Playwright actions",
    inputSchema: {
      type: "object",
      properties: {
        options: {
          type: "object",
          description: "Code generation options",
          properties: {
            outputPath: { 
              type: "string", 
              description: "Directory path where generated tests will be saved (use absolute path)" 
            },
            testNamePrefix: { 
              type: "string", 
              description: "Prefix to use for generated test names (default: 'GeneratedTest')" 
            },
            includeComments: { 
              type: "boolean", 
              description: "Whether to include descriptive comments in generated tests" 
            }
          },
          required: ["outputPath"]
        }
      },
      required: ["options"]
    }
  },

• src/tools.ts:485-486 (registration)

  Lists 'start_codegen_session' in the CODEGEN_TOOLS array, categorizing it for conditional handling.

  export const CODEGEN_TOOLS = [
    'start_codegen_session',