Cedardiff MCP Server

Instructions

Implementation Reference

• src/index.ts:88-144 (handler)

  Main handler for the 'edit_file' tool within the CallToolRequestSchema. Validates the tool name, parses arguments, reads the target file, executes the CEDARScript, writes changes back, and returns success/error content.

  this.server.setRequestHandler(CallToolRequestSchema, async (request) => {
    if (request.params.name !== 'edit_file') {
      throw new McpError(
        ErrorCode.MethodNotFound,
        `Unknown tool: ${request.params.name}`
      );
    }
  
    if (!request.params.arguments || 
        typeof request.params.arguments.script !== 'string' ||
        typeof request.params.arguments.workingDir !== 'string') {
      throw new McpError(
        ErrorCode.InvalidParams,
        'Missing or invalid file/script arguments'
      );
    }
  
    const { script, workingDir } = request.params.arguments;
    
    try {
      // Extract file path from script
      const fileMatch = script.match(/FILE\s+['"]([^'"]+)['"]/i);
      if (!fileMatch) {
        throw new Error('Script must specify a file using FILE "path"');
      }
      const filePath = path.resolve(workingDir, fileMatch[1]);
  
      // Read the file
      const content = fs.readFileSync(filePath, 'utf8');
  
      // Parse and execute the CEDARScript
      const newContent = this.executeCedarScript(content, script);
  
      // Write back to file
      fs.writeFileSync(filePath, newContent);
  
      return {
        content: [
          {
            type: 'text',
            text: `Successfully edited ${filePath}`,
          },
        ],
      };
    } catch (error: unknown) {
      const errorMessage = error instanceof Error ? error.message : String(error);
      return {
        content: [
          {
            type: 'text',
            text: `Error editing file: ${errorMessage}`,
          },
        ],
        isError: true,
      };
    }
  });

• src/index.ts:70-83 (schema)

  Input schema definition for the 'edit_file' tool, specifying required 'script' and 'workingDir' parameters.

  inputSchema: {
    type: 'object',
    properties: {
      script: {
        type: 'string',
        description: 'CEDARScript commands to execute'
      },
      workingDir: {
        type: 'string',
        description: 'Working directory for resolving file paths'
      }
    },
    required: ['script', 'workingDir'],
  },

• src/index.ts:65-86 (registration)

  Registers the 'edit_file' tool in the ListToolsRequestSchema handler, providing name, description, and schema.

  this.server.setRequestHandler(ListToolsRequestSchema, async () => ({
    tools: [
      {
        name: 'edit_file',
        description: 'Edit a file using CEDARScript syntax',
        inputSchema: {
          type: 'object',
          properties: {
            script: {
              type: 'string',
              description: 'CEDARScript commands to execute'
            },
            workingDir: {
              type: 'string',
              description: 'Working directory for resolving file paths'
            }
          },
          required: ['script', 'workingDir'],
        },
      },
    ],
  }));

• src/index.ts:147-160 (helper)

  Helper function that splits file content into lines, parses the CEDARScript into commands, executes them, and rejoins the lines.

  private executeCedarScript(content: string, script: string): string {
    const lines = content.split('\n');
    let result = [...lines];
  
    // Parse the script into commands
    const commands = this.parseScript(script);
  
    // Execute each command
    for (const command of commands) {
      result = this.executeCommand(command, result);
    }
  
    return result.join('\n');
  }

• src/index.ts:162-190 (helper)

  Helper function that parses the CEDARScript string into an array of command objects by splitting on semicolons and dispatching to specific parsers.

  private parseScript(script: string): Array<{
    type: 'update' | 'create' | 'rm_file' | 'mv_file';
    caseStatement?: CaseStatement;
    filePath?: string;
    content?: string;
    targetPath?: string;
  }> {
    const commands: Array<{
      type: 'update' | 'create' | 'rm_file' | 'mv_file';
      targetPath?: string;
    }> = [];
    
    // Split into individual commands (separated by semicolons)
    const commandStrings = script.split(';').map(cmd => cmd.trim()).filter(Boolean);
  
    for (const cmdStr of commandStrings) {
      if (cmdStr.startsWith('UPDATE')) {
        commands.push(this.parseUpdateCommand(cmdStr));
      } else if (cmdStr.startsWith('CREATE')) {
        commands.push(this.parseCreateCommand(cmdStr));
      } else if (cmdStr.startsWith('RM')) {
        commands.push(this.parseRmCommand(cmdStr));
      } else if (cmdStr.startsWith('MV')) {
        commands.push(this.parseMvCommand(cmdStr));
      }
    }
  
    return commands;
  }