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Vikrant Bagal
Vikrant Bagal

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Using Prebuilt Agents with Coding Agents: A Complete Guide for Full-Stack .NET, Node.js & Frontend

#dotnet #react #javascript #webdev

The AI coding agent landscape has exploded in 2026. Tools like Claude Code, OpenCode, and Cursor are transforming how we build software, but the real power comes from integrating them with prebuilt agents that handle specialized tasks.

This guide covers everything you need to know about using prebuilt agents with coding agents for full-stack .NET, Node.js, and frontend development.

📋 What You'll Learn

  1. Best Agents Available - Claude Code, OpenCode, Cursor, and specialized prebuilt frameworks
  2. Efficient Usage Patterns - How to leverage each agent's strengths
  3. Pitfalls to Avoid - Common mistakes that waste tokens and time
  4. Context Saving Tips - Keep your sessions productive and cost-effective
  5. Step-by-Step Setup - Complete configuration for your stack

🏆 Best Coding Agents in 2026

Quick Comparison Table

Feature OpenCode Claude Code Cursor
Type Terminal TUI Terminal CLI VS Code fork
Open Source ✅ Yes (MIT) ⚠️ Source-available ❌ Proprietary
LLM Providers 75+ via Models.dev Claude only Claude, GPT, Gemini
Multi-Model Routing ✅ Native ❌ No ⚠️ Manual switch
MCP Support ✅ Yes ✅ Yes ✅ Yes
Multi-Agent 10 agents (OmO) Subagent spawning Composer
Edit Tool Hashline (OmO) Built-in Edit Inline diff
Price Free + API costs $20/mo (Pro) $20/mo (Pro)
Best For Power users, multi-model Deep codebase work Visual developers

1. OpenCode + Oh-My-OpenAgent

OpenCode is the open-source terminal powerhouse that routes to 75+ LLM providers. Combined with Oh-My-OpenAgent (OmO), it becomes a multi-agent system with 10 specialized agents.

Why Choose OpenCode?

  • Model Freedom: Use any provider, switch models per task, avoid vendor lock-in
  • Performance: Go binary with TUI means sub-second startup
  • OmO Ecosystem: 10 specialized agents, Hashline edits, automated model routing
  • LSP Integration: Real code intelligence via language servers
  • Cost Control: Pay only for API calls you make

Installation 

# Install OpenCode
curl -fsSL https://opencode.ai/install | bash

# Verify installation
opencode --version
# Output: opencode version 1.4.0

# Install Oh-My-OpenAgent
git clone https://github.com/nicepkg/oh-my-openagent.git
cd oh-my-openagent
npm install && npm run setup
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Configuration for Full-Stack Development

Create a configuration file for your stack:

# ~/.opencode/config.yml
providers:
  anthropic:
    api_key: ${ANTHROPIC_API_KEY}
  openai:
    api_key: ${OPENAI_API_KEY}
  google:
    api_key: ${GOOGLE_API_KEY}

routing:
  # Route tasks to appropriate models
  code_generation: "gpt-4o"      # Fast, cheap for simple code
  architecture: "claude-opus"    # Better reasoning for decisions
  refactoring: "claude-sonnet"   # Balanced for multi-file changes

omO_agents:
  enabled: true
  agents:
    - frontend
    - backend
    - database
    - testing
    - deployment
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Usage Example for Full-Stack 

# Start OpenCode in your project
opencode

# Within OpenCode, use OmO agents:
# @frontend - React components, CSS, state management
# @backend - .NET controllers, services, APIs
# @database - Entity Framework, migrations, queries
# @testing - Unit tests, integration tests

# Example prompt:
> @frontend Create a React component for user login form with validation
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2. Claude Code

Claude Code is Anthropic's terminal-based agent built around Claude Opus 4.6, which achieves an 80.8% SWE-bench score (highest verified as of 2026).

Why Choose Claude Code?

  • Best Single-Model Performance: Opus 4.6 genuinely outperforms alternatives
  • Deep Git Integration: Commits, PRs, branch management built-in
  • Hooks System: Enforce quality gates automatically
  • Project Memory: CLAUDE.md persists context across sessions
  • Agentic Reliability: Handles complex multi-step tasks without losing track

Installation 

# Install Claude Code
npm install -g @anthropic/claude-code

# Verify installation
claude --version

# Start a session in your project
cd /path/to/project
claude
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Configuration for Full-Stack .NET + Node.js

CLAUDE.md (project-level memory file):

# Project: Full-Stack Application

## Stack
- Backend: .NET 8 / ASP.NET Core (Clean Architecture)
- Frontend: React 18 with TypeScript
- Database: PostgreSQL with Entity Framework Core
- API: RESTful with OpenAPI/Swagger

## Coding Standards
- Use async/await for all I/O operations
- Follow SOLID principles for .NET classes
- React components should be functional with hooks
- Unit tests: xUnit for .NET, Jest for React
- Code style: EditorConfig + Prettier

## Architecture Decisions
- Backend uses CQRS pattern with MediatR
- Frontend uses React Query for server state
- Authentication: JWT with refresh tokens
- Deployment: Docker + Azure

## Common Commands
- Build backend: `dotnet build`
- Run backend: `dotnet run --project src/API`
- Build frontend: `npm run build`
- Run tests: `dotnet test` and `npm test`
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.claude/settings.local.json (per-user settings):

{
  "env": {
    "ANTHROPIC_API_KEY": "your-api-key",
    "DATABASE_CONNECTION": "your-connection-string"
  },
  "permissions": {
    "allow": ["Bash", "Glob", "Grep", "Write", "Edit"]
  }
}
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Usage Examples 

# Start Claude Code
claude

# Within Claude Code:

# 1. Create a new API endpoint
> Create a new API endpoint for user registration in src/API/Controllers/AccountController.cs

# 2. Implement a React component
> Create a React component for user profile display with edit functionality

# 3. Full-stack feature
> Implement a complete "forgot password" flow:
> - Backend: .NET controller, service, email template
> - Frontend: React form with validation
> - Database: Update user table with reset token

# 4. Use subagents for parallel work
> /subagent backend "Create EF Core migration for password reset tokens"
> /subagent frontend "Build password reset form component"
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3. Cursor

Cursor is the VS Code fork that embeds AI directly into the editing experience.

Why Choose Cursor?

  • Full IDE Experience: Syntax highlighting, debugging, extensions, terminal
  • Visual Diff Review: See exactly what changes before accepting
  • Tab Completion: AI-powered autocomplete that learns patterns
  • Lower Learning Curve: If you know VS Code, you know Cursor
  • Multi-Model Access: Claude, GPT-4o, Gemini, custom models

Installation

  1. Download from cursor.com
  2. Import your VS Code settings
  3. Sign in with your account

Configuration for Full-Stack Development

.cursor/rules/ (AI rules directory):

# .cursor/rules/dotnet.mdc
---
applyTo: "**/*.cs"
---
# .NET Coding Standards
- Use async/await for I/O operations
- Follow Clean Architecture patterns
- Use Entity Framework Core for data access
- Implement proper error handling with try-catch
- Write unit tests with xUnit

# .cursor/rules/react.mdc
---
applyTo: "**/*.{tsx,jsx}"
---
# React Coding Standards
- Use functional components with hooks
- Implement TypeScript interfaces
- Use React Query for server state
- Follow component composition patterns
- Write tests with Jest + React Testing Library
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.cursor/indexing_allowlist (control what gets indexed):

src/**/*.cs
src/**/*.tsx
src/**/*.ts
!node_modules/**
!bin/**
!obj/**
!*.min.js
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Usage Example 

# Start Cursor and open your project folder

# Use Composer for multi-file changes:
# Cmd/Ctrl + I to open Composer

# Example prompt for full-stack feature:
"Add user profile feature:
- Backend: Update User entity, create ProfileController
- Frontend: Build profile page with form
- Tests: Add integration tests"

# Use Tab completion:
# Type function signature, Tab to auto-generate implementation
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4. Prebuilt Agent Frameworks

Agent-Bober

A multi-agent harness for building applications autonomously with any LLM.

Installation:

npm install agent-bober
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Configuration:

// agent-bober.config.js
module.exports = {
  pipeline: ["researcher", "planner", "curator", "generator", "evaluator"],
  models: {
    primary: "claude-3-5-sonnet",
    fallback: "gpt-4o"
  },
  mcpServers: {
    cursor: { enabled: true },
    windsurf: { enabled: true }
  }
};
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Usage:

# Run full-stack development pipeline
npx agent-bober --task "Build user authentication system"

# The pipeline will:
# 1. Research: Gather requirements and best practices
# 2. Plan: Create architecture and implementation plan
# 3. Curate: Review existing codebase for integration points
# 4. Generate: Create backend (.NET) and frontend (React) code
# 5. Evaluate: Run tests and review code quality
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Specialist-Agent

27+ specialized agents with 21 skills for different frameworks.

Installation:

npm install specialist-agent
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Setup for .NET + React Stack:

// specialist-agent.config.js
const { SpecialistAgent } = require('specialist-agent');

const agent = new SpecialistAgent({
  stack: ['dotnet', 'react', 'nodejs'],
  frameworkPacks: ['react', 'nextjs']
});

// Use specialized agents
agent.use('dotnet-architect').planSolution('User Management');
agent.use('react-developer').createComponents('User Dashboard');
agent.use('nodejs-backend').buildApi('User API');
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🎯 How to Use These Agents Efficiently

Agent Selection Strategy

Task Type Best Agent Why
Quick edits Cursor Visual diff, inline changes
Deep refactoring Claude Code Subagent planning, git integration
Multi-provider OpenCode Model routing, cost optimization
Autonomous builds Agent-Bober Full pipeline automation
Framework-specific Specialist-Agent Pre-built skills for your stack

Workflow Patterns

Pattern 1: Parallel Development

Claude Code (Main)
  ├─ Subagent: Backend (.NET)
  ├─ Subagent: Frontend (React)
  └─ Subagent: Database (EF Core)

All subagents work simultaneously, then merge results
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Pattern 2: Sequential Pipeline

OpenCode with OmO
  ├─ Researcher: Gather requirements
  ├─ Planner: Create architecture
  ├─ Generator: Write code
  └─ Evaluator: Test and review
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Pattern 3: Visual Review

Cursor Composer
  ├─ Describe feature
  ├─ Review visual diff
  ├─ Accept/reject changes
  └─ Iterate as needed
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⚠️ Pitfalls to Avoid

1. Vague Prompts

❌ "Fix the login page"
✅ "Update src/components/LoginForm.tsx to add email validation using react-hook-form"

2. Full Context on Every Turn

❌ Asking agents to read entire codebase each time
✅ Use #file: references and scoped prompts

3. No Project Memory

❌ Starting fresh every session
✅ Use CLAUDE.md, .cursor/rules, or OpenCode memory files

4. Expensive Models for Simple Tasks

❌ Using Claude Opus for simple formatting
✅ Route simple tasks to cheaper models (GPT-4.1, Haiku)

5. Ignoring Git History

❌ Manual commits without context
✅ Let Claude Code handle commits with meaningful messages

6. No Testing Strategy

❌ Generating code without tests
✅ Always request tests alongside implementation

7. Context Rot

❌ Letting context window fill to 150K+ tokens
✅ Compact context before it degrades model performance

💾 Context Saving Tips

1. Context Engineering (Foojay.io's 8 Levers)

Lever A: Scope Your Asks

# Bad: "Refactor the order email"
# Good: "Refactor #file:src/Email/OrderConfirmationService.cs to use new template engine"

# Use #file: syntax in Claude Code
# Use @ in Cursor
# Use explicit paths in OpenCode
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Lever B: Prompt Caching - Order Matters

Static at top (cached):
- Tool definitions
- System prompt
- Custom instructions
- Skills/rules

Dynamic at bottom:
- Retrieved files
- Conversation history
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Lever C: Tool & MCP Hygiene

// .vscode/mcp.json - keep it short
{
  "servers": {
    "filesystem": { "command": "npx", "args": ["-y", "@modelcontextprotocol/server-filesystem"] }
    // Disable servers you don't use
  }
}
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Lever D: Custom Instructions

# CLAUDE.md or .github/copilot-instructions.md

## Rules
- Use async/await for all I/O
- Write tests for new features
- Follow Clean Architecture
- Use #file: for specific files
- Reply with diffs, not novels
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Lever E: Model Routing

# Start cheap, escalate when stuck
routing:
  inline_completions: "gpt-4.1"      # 0x cost
  real_coding: "claude-sonnet"       # 1x cost
  long_refactor: "claude-sonnet-long" # 1x cost
  hard_reasoning: "claude-opus"      # 10x cost
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Lever F: Output Discipline

# Bad: "Explain what you're about to do..."
# Good: "Reply with unified diff only, no commentary"
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Lever G: Repo Hygiene

# Exclude from indexing
# .cursorignore or .opencodeignore
node_modules/
bin/
obj/
*.min.js
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Lever H: Observability

# Monitor token usage
# Claude Code shows token count per turn
# OpenCode has --verbose flag
# Cursor shows in output panel
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2. Session Management

For Long Sessions:

# Claude Code: Use /compact to reduce context
# OpenCode: Start new session with /new
# Cursor: Use @workspace for fresh context
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For Multi-Day Projects:

# Create project memory files
echo "# Project Context" > CLAUDE.md
echo "Last updated: $(date)" >> CLAUDE.md

# Add key decisions and architecture notes
# This persists across sessions
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3. Token Optimization Strategies

Strategy Savings Implementation
File scoping 50-70% Use #file: references
Prompt caching 90% for static content Order prompts correctly
Model routing 10x cost difference Route simple tasks to cheap models
Output discipline 60-80% Request diffs, not explanations
Context compaction Prevents rot Compact at 50K tokens

🔧 Step-by-Step Setup Guide

Step 1: Install Your Chosen Agent

Option A: Claude Code (Recommended for .NET + Full-Stack)

npm install -g @anthropic/claude-code
claude --version
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Option B: OpenCode (For Multi-Model Flexibility)

curl -fsSL https://opencode.ai/install | bash
opencode --version
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Option C: Cursor (For Visual Development)

# Download from cursor.com
# Import VS Code settings
# Install extensions
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Step 2: Configure Project Structure 

my-project/
├── .claude/                    # Claude Code config
│   └── settings.local.json
├── CLAUDE.md                   # Project memory
├── .cursor/                    # Cursor config
│   └── rules/
├── .opencode/                  # OpenCode config
├── src/
│   ├── API/                   # .NET Backend
│   ├── Web/                   # React Frontend
│   └── Shared/                # Common code
├── tests/
└── docker-compose.yml
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Step 3: Set Up CLAUDE.md (For Claude Code) 

# Full-Stack Project: My Application

## Stack Overview
- **Backend**: .NET 8 / ASP.NET Core / Clean Architecture
- **Frontend**: React 18 / TypeScript / Vite
- **Database**: PostgreSQL / Entity Framework Core
- **Auth**: JWT with refresh tokens
- **Testing**: xUnit (backend) / Jest (frontend)

## Project Structure
- src/API - ASP.NET Core Web API
- src/Application - Business logic (CQRS with MediatR)
- src/Infrastructure - EF Core, external services
- src/Web - React frontend
- tests/ - Unit and integration tests

## Coding Standards
- Use async/await for all I/O operations
- Follow SOLID principles
- Write tests for new features
- Use repository pattern for data access
- Implement proper error handling

## Common Commands
- Build backend: `dotnet build`
- Run backend: `dotnet run --project src/API`
- Build frontend: `cd src/Web && npm run build`
- Run tests: `dotnet test` and `cd src/Web && npm test`
- Run migrations: `dotnet ef database update`

## Architecture Decisions
- Backend uses CQRS pattern with MediatR
- Frontend uses React Query for server state management
- API follows RESTful conventions with OpenAPI documentation
- Authentication uses JWT tokens with refresh mechanism
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Step 4: Configure Agent Settings

Claude Code Settings (.claude/settings.local.json):

{
  "env": {
    "ANTHROPIC_API_KEY": "your-key-here",
    "DATABASE_CONNECTION": "your-connection-string"
  },
  "permissions": {
    "allow": ["Bash", "Glob", "Grep", "Write", "Edit"]
  }
}
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OpenCode Configuration (.opencode/config.yml):

providers:
  anthropic:
    api_key: ${ANTHROPIC_API_KEY}
  openai:
    api_key: ${OPENAI_API_KEY}

routing:
  code_generation: "gpt-4o"
  architecture: "claude-opus"
  refactoring: "claude-sonnet"
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Cursor Rules (.cursor/rules/dotnet.mdc):

---
applyTo: "**/*.cs"
---
# .NET Standards
- Use Clean Architecture
- Implement CQRS with MediatR
- Write xUnit tests
- Follow async patterns
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Step 5: Start Developing

Claude Code Workflow:

cd my-project
claude

# Prompt examples:
> Create user registration API in src/API/Controllers/AccountController.cs

> Build login form component in src/Web/src/components/LoginForm.tsx

> /subagent backend "Create EF Core migration for user table"
> /subagent frontend "Build user dashboard component"
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OpenCode Workflow:

cd my-project
opencode

# Use OmO agents:
@backend Create user authentication service
@frontend Build login form with validation
@database Design user schema with EF Core
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Cursor Workflow:

# Open project in Cursor
# Use Composer (Cmd/Ctrl+I)
# Describe feature, review diff, accept changes
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Step 6: Monitor and Optimize

Check Token Usage:

  • Claude Code: Shows tokens per turn
  • OpenCode: Use --verbose flag
  • Cursor: View in output panel

Compact Context When Needed:

  • Claude Code: /compact command
  • OpenCode: Start new session with /new
  • Cursor: Use @workspace for fresh context

Review Session History:

# Claude Code: /history
# OpenCode: Session history in ~/.opencode/
# Cursor: Output panel logs
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📊 Full-Stack Development Workflow

Daily Development Cycle

Morning: Planning

Claude Code Session:
1. Review CLAUDE.md for project context
2. Ask: "What should I work on today?"
3. Plan feature implementation
4. Create subagents for parallel work
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Development: Implementation

Claude Code:
1. Create backend API endpoint
2. Build frontend component
3. Add database migration
4. Write unit tests

OpenCode:
1. Use @backend for .NET code
2. Use @frontend for React code
3. Use @testing for test generation
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Review: Quality Assurance

Cursor:
1. Review visual diffs
2. Run tests
3. Check for edge cases
4. Refactor as needed
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Evening: Cleanup

Claude Code:
1. /compact to reduce context
2. Commit with meaningful messages
3. Update CLAUDE.md with decisions
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Feature Development Example

Task: User Profile Management

# 1. Backend (.NET)
> Create UserProfile entity with EF Core migration
> Build UserProfileController with CRUD endpoints
> Implement UserProfileService with business logic
> Write integration tests

# 2. Frontend (React)
> Build UserProfile component with edit functionality
> Create useUserProfile hook with React Query
> Add form validation with react-hook-form
> Write Jest tests

# 3. Integration
> Connect frontend to backend API
> Test end-to-end flow
> Add error handling
> Deploy to staging
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🎯 Conclusion

Using prebuilt agents with coding agents transforms full-stack development from a solo effort into a collaborative team of AI specialists. The key is:

  1. Choose the right agent for your workflow (Claude Code for deep work, OpenCode for flexibility, Cursor for visual development)
  2. Use prebuilt frameworks like Agent-Bober or Specialist-Agent for repeatable patterns
  3. Master context management to keep sessions productive and cost-effective
  4. Follow the step-by-step setup to configure your environment properly

Start with Claude Code for .NET + Node.js + React stacks, integrate OpenCode for multi-model routing when needed, and use Cursor for visual review and debugging. Combine with prebuilt agent frameworks for autonomous development pipelines.

Ready to get started? Pick one agent, set up CLAUDE.md, and start building!

LinkedIn Profile: https://www.linkedin.com/in/vikrant-bagal

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