Main Entry Skill

Purpose

Generate the application entry point file (src/main.ts). Creates different versions based on application architecture:

• Micro-frontend: Includes single-spa lifecycle methods and CSS isolation
• Standalone: Traditional Vue SPA initialization

Input Parameters

• application_type: "micro-frontend" or "standalone"
• application_id: The application ID for CSS isolation and monitoring service name
• enable_datadog: Boolean to include Datadog RUM monitoring
• state_management: "vuex" or "pinia"

Output

Create the file: src/main.ts

Configuration Requirements

Core Imports

Vue Essentials

• Import Vue's createApp function for application initialization
• For micro-frontends: Also import h (render function) for programmatic component rendering

Application Components

• Import root App component
• Import router instance from router configuration
• Import store instance (Vuex or Pinia depending on state_management parameter)

Monitoring (Optional)

If enable_datadog is true:

• Import Datadog RUM SDK
• Import environment constants for Datadog configuration (app ID, client token, environment, version)

Micro-Frontend Specific

If application_type is "micro-frontend":

• Import single-spa integration library for Vue
• Import application ID constant for CSS isolation

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Micro-Frontend Architecture

Purpose

Enable the application to run as part of a larger single-spa ecosystem while maintaining CSS isolation and the ability to run independently.

Single-SPA Lifecycle Setup

Lifecycle Configuration

Create lifecycle object using the single-spa Vue adapter with:

App Options

• Use render function to return the root App component
• Pass any necessary props to the App component

Instance Handler

• Register router plugin
• Register state management plugin (Vuex/Pinia)
• Register any other global plugins or configurations

Lifecycle Exports

Bootstrap Export

• Export the bootstrap lifecycle method
• Runs once when the micro-frontend is first loaded
• Initialize any one-time setup

Mount Export

• Export custom mount function
• CSS Restoration Logic:
  • Check if style tag with application ID exists in DOM
  • If exists and not cached: cache the style tag content
  • If doesn't exist but cached: recreate the style tag with cached content
  • Append style tag to document head
  • Purpose: Preserve CSS when navigating between micro-frontends
• Call the underlying single-spa mount lifecycle
• Application becomes active and visible

Unmount Export

• Export custom unmount function
• Call the underlying single-spa unmount lifecycle
• CSS Cleanup Logic:
  • Find and remove style tag with application ID from DOM
  • Keep cached version for restoration on next mount
  • Purpose: Prevent CSS conflicts with other micro-frontends
• Application becomes inactive

CSS Isolation Strategy

The Problem: In micro-frontend architectures, multiple applications' CSS can conflict

The Solution: Style Tag Management

• Each micro-frontend has a unique style tag ID
• Cache style content on first mount
• Remove style tag on unmount (cleanup)
• Restore cached styles on remount (avoid re-download)
• Use unique ID derived from application identifier

Key Concepts:

• Styles are scoped by application
• No CSS pollution between micro-frontends
• Performance optimization through caching
• Seamless transitions between applications

Standalone Fallback Mode

Purpose: Allow micro-frontend to run independently for development and testing

Detection Logic:

• Check if single-spa context exists (e.g., window.singleSpaNavigate)
• If single-spa is NOT present: mount application directly

Fallback Initialization:

• Create Vue app instance
• Register router plugin
• Register state management plugin
• Mount to DOM element (typically #app)

Benefits:

• Develop and test micro-frontend in isolation
• No need for full single-spa orchestrator during development
• Faster feedback loop
• Easier debugging

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Standalone Architecture

Purpose

Traditional single-page application (SPA) with straightforward initialization.

Application Initialization

Create App Instance

• Use createApp with root App component

Register Plugins

• Register router for navigation
• Register state management (Vuex/Pinia)
• Register any other global plugins

Mount Application

• Mount to DOM element (typically #app)
• Application becomes active immediately

Key Differences from Micro-Frontend:

• No lifecycle exports
• No CSS isolation logic
• No single-spa integration
• Simpler, more direct initialization

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Monitoring Integration (Optional)

Datadog RUM Configuration

If enable_datadog is true, initialize Real User Monitoring:

Required Configuration

Application Identification

• Application ID: From environment variable
• Client Token: From environment variable (authentication)
• Site: Datadog site domain
• Service Name: Use application_id parameter for consistent identification
• Environment: From environment variable (dev, staging, prod)
• Version: Application version from package.json

Session Recording

Sample Rates

• Session Sample Rate: Percentage of sessions to track
• Session Replay Sample Rate: Percentage of sessions to record
• Start Manually: Control when recording starts (performance optimization)

Tracking Options

User Interactions

• Track clicks, form inputs, navigation
• Understand user behavior patterns

Resources

• Track API calls, asset loading
• Monitor performance and failures

Long Tasks

• Detect performance bottlenecks
• Identify slow operations

Privacy Settings

Default Privacy Level

• Mask sensitive user inputs
• Comply with privacy regulations
• Options: mask, mask-user-input, allow

Experimental Features

• Feature flags tracking
• A/B testing integration
• Enable as needed

Monitoring Best Practices

• Initialize monitoring as early as possible in application lifecycle
• Use environment variables for configuration (never hardcode tokens)
• Set appropriate sample rates based on traffic volume
• Configure privacy settings according to compliance requirements
• Use service name consistently across all micro-frontends for correlation

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State Management Integration

Vuex Integration

If state_management is "vuex":

• Import store from ./store directory
• Store is typically a Vuex store instance with modules
• Register with app.use(store)

Pinia Integration

If state_management is "pinia":

• Import Pinia instance from ./stores directory
• Pinia is the modern, recommended state management for Vue 3
• Register with app.use(pinia)

Key Differences

• Vuex: Module-based, mutations + actions pattern
• Pinia: Store-based, direct state mutation, better TypeScript support
• Both are registered the same way via app.use()

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Architecture Decision Logic

When to Use Micro-Frontend Template

Use Cases:

• Part of a larger multi-application ecosystem
• Need to run alongside other micro-frontends
• Shared navigation/layout across multiple apps
• Team owns a specific domain/feature area
• Need independent deployment of features

Requirements:

• Single-spa orchestrator (root config)
• CSS isolation between applications
• Ability to run independently for development

When to Use Standalone Template

Use Cases:

• Single application deployment
• Traditional SPA architecture
• No need for micro-frontend complexity
• Simpler deployment and hosting

Benefits:

• Simpler codebase
• Easier to understand
• Fewer dependencies
• Standard Vue patterns

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Validation

After generating the entry file:

Micro-Frontend Validation

1. Lifecycle Exports: Verify bootstrap, mount, and unmount are exported
2. CSS Isolation: Confirm style tag is created with unique ID
3. Standalone Mode: Test that app runs without single-spa present
4. Router Integration: Verify navigation works in both modes
5. Store Integration: Confirm state management is accessible
6. Monitoring: Check Datadog RUM initializes if enabled

Standalone Validation

1. App Mounting: Verify app mounts to DOM successfully
2. Router Integration: Test navigation works
3. Store Integration: Confirm state management is accessible
4. Monitoring: Check Datadog RUM initializes if enabled
5. Console Errors: Ensure no errors during initialization

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Best Practices

Error Handling

• Wrap initialization in try-catch for production debugging
• Log errors to monitoring service
• Provide fallback UI for initialization failures

Performance

• Initialize monitoring early but asynchronously if possible
• Lazy load non-critical plugins
• Keep main entry file focused and minimal

Type Safety

• Use TypeScript for type checking
• Define types for single-spa lifecycle props
• Type environment constants properly

Development Experience

• Support hot module replacement (HMR) in development
• Provide clear error messages for misconfiguration
• Enable source maps for debugging

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Philosophy

This entry file aims to:

• Bootstrap the Application: Initialize Vue and all necessary plugins
• Support Multiple Architectures: Work as micro-frontend or standalone SPA
• Enable Monitoring: Track performance and user behavior
• Maintain Isolation: Prevent conflicts in multi-app environments
• Facilitate Development: Allow independent development and testing
• Stay Maintainable: Clear, focused, easy to understand

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Future Compatibility

When Vue, single-spa, or monitoring tools evolve:

• Adopt new Vue initialization APIs as they become available
• Update single-spa integration to use modern lifecycle patterns
• Leverage improved CSS isolation techniques if introduced
• Update monitoring SDK to latest API versions
• Replace deprecated methods with modern equivalents
• Maintain core principles: clean initialization, proper lifecycle management, effective monitoring

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Common Variations

Multiple Store Types

• May need to register multiple Pinia stores
• Could have both global and feature-specific stores
• Coordinate registration order if dependencies exist

Additional Plugins

Consider registering:

• UI component libraries
• Icon libraries
• Form validation libraries
• Internationalization (i18n)
• Authentication plugins
• Custom directives

Alternative Monitoring Solutions

• Google Analytics
• Sentry for error tracking
• Custom analytics solutions
• Application Performance Monitoring (APM) tools

Environment-Specific Initialization

• Development: Enable debug tools, verbose logging
• Staging: Enable monitoring, disable debug tools
• Production: Full monitoring, error tracking, optimizations