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

dels. This allows you to swap providers without changing prompts.

File: ai-workflow.config.json

{
  "version": "1.0",
  "routing": {
    "strategies": {
      "quick_edit": {
        "model": "gpt-4o-mini",
        "max_tokens": 2048,
        "description": "Inline fixes, minor refactors, comment generation"
      },
      "feature_impl": {
        "model": "claude-sonnet-4",
        "max_tokens": 8192,
        "description": "New components, API endpoints, standard logic"
      },
      "architecture": {
        "model": "claude-opus-4.6",
        "max_tokens": 16384,
        "description": "Cross-module changes, design decisions, complex debugging"
      },
      "cost_saver": {
        "model": "gemini-flash-2",
        "max_tokens": 4096,
        "description": "Documentation, test scaffolding, boilerplate"
      }
    },
    "fallback_chain": ["claude-sonnet-4", "gpt-4o", "gemini-flash-2"]
  },
  "context": {
    "max_files": 50,
    "exclude_patterns": ["**/bin/**", "**/obj/**", "**/node_modules/**", "**/*.min.js"]
  }
}

Rationale:

• Granular Routing: Assigning gpt-4o-mini to quick edits prevents burning expensive tokens on trivial changes.
• Fallback Chain: Ensures continuity if a primary provider experiences latency or rate limiting.
• Context Limits: Explicitly bounding file counts prevents context window overflow, which degrades model performance.

2. Implement Persistent Context

Agents lose state between sessions. To maintain productivity, inject a structured context file that acts as the "source of truth" for the project. This file should be version-controlled and updated by the team.

File: AGENTS.md

# Project Context: Enterprise Inventory System

## Tech Stack
- **Backend:** .NET 8, ASP.NET Core, Entity Framework Core, MediatR (CQRS)
- **Frontend:** React 18, TypeScript, React Query, Tailwind CSS
- **Database:** PostgreSQL
- **Auth:** JWT with Refresh Tokens

## Domain Rules
- Inventory counts must be updated within a transaction scope.
- All API responses must wrap data in a standard `Result<T>` envelope.
- React components must use functional patterns with strict TypeScript interfaces.

## Coding Standards
- **Naming:** PascalCase for classes/methods, camelCase for variables.
- **Error Handling:** Use global exception middleware; never swallow exceptions.
- **Testing:** xUnit for .NET, Vitest for React. Coverage threshold: 80%.

## Common Commands
- Build: `dotnet build && npm run build`
- Test: `dotnet test && npm run test`
- Migrate: `dotnet ef database update`

Rationale:

• Domain Rules: Prevents agents from generating code that violates business logic.
• Standardization: Enforces consistency across agents that might otherwise drift in style.
• Command Reference: Reduces hallucination regarding build/test scripts.

3. Establish Quality Gates

Automated hooks are non-negotiable in production. Configure the agent environment to run validation before committing changes.

File: .husky/pre-commit

#!/bin/sh
. "$(dirname "$0")/_/husky.sh"

# Run linting and type checking
npm run lint:fix
npm run type-check

# Run backend tests
dotnet test --no-build --verbosity quiet

# Ensure no TODO comments from agents remain
if grep -r "TODO: AI" --include="*.cs" --include="*.tsx" .; then
  echo "Error: AI-generated TODOs found. Resolve before committing."
  exit 1
fi

Rationale:

• Automated Validation: Catches syntax errors and type mismatches immediately.
• Artifact Removal: Prevents AI placeholders from leaking into the codebase.
• Consistency: Ensures all code, regardless of origin, meets the same standards.

Pitfall Guide

1. Context Overflow

   • Explanation: Loading entire directories or irrelevant files into the agent's context window causes attention dilution, leading to hallucinations and slower responses.
   • Fix: Use strict indexing allowlists and exclude patterns. Regularly prune AGENTS.md to keep it concise.

2. Model Mismatch

   • Explanation: Using a high-reasoning model like Opus 4.6 for simple tasks like renaming variables wastes budget and increases latency.
   • Fix: Implement the routing strategy defined in the Core Solution. Audit token usage weekly to identify misrouted tasks.

3. Parallel Race Conditions

   • Explanation: When using multi-agent systems that spawn subagents, concurrent edits to the same file can cause merge conflicts or overwrites.
   • Fix: Enforce file ownership rules. Use sequential pipelines for interdependent changes, or configure the orchestrator to lock files during agent operations.

4. Prompt Drift

   • Explanation: Vague instructions like "improve performance" lead to unpredictable changes. Agents may optimize the wrong metrics or break existing functionality.
   • Fix: Use structured prompts with acceptance criteria. Example: "Optimize the GetInventory query to reduce execution time by 20% without altering the return schema."

5. Hook Bypass

   • Explanation: Agents may attempt to skip tests or linting to complete tasks faster, especially under token constraints.
   • Fix: Configure agent permissions to disallow skipping hooks. Enforce hooks at the CI/CD level as a secondary safety net.

6. Vendor Lock-in via Hardcoded Keys

   • Explanation: Embedding API keys directly in configuration files or prompts creates security risks and limits flexibility.
   • Fix: Use environment variables and secret management tools. Abstract provider configuration so models can be swapped without code changes.

7. Ignoring LSP Intelligence

   • Explanation: Relying solely on text completion without leveraging Language Server Protocol (LSP) data results in code that doesn't integrate well with the existing type system.
   • Fix: Ensure your agent setup supports LSP integration. This provides real-time type checking and symbol resolution, reducing integration errors.

Production Bundle

Action Checklist

• Define Routing Rules: Create ai-workflow.config.json mapping task types to cost-effective models.
• Establish Context File: Write AGENTS.md with stack details, domain rules, and commands; commit to version control.
• Configure Indexing: Set up allowlists to exclude build artifacts and dependencies from agent context.
• Implement Hooks: Add pre-commit hooks for linting, type-checking, and test execution.
• Secure Secrets: Move all API keys to environment variables; verify no secrets in config files.
• Test Fallbacks: Simulate provider outages to ensure fallback chains function correctly.
• Audit Costs: Review token usage metrics after the first week; adjust routing thresholds based on data.

Decision Matrix

Scenario	Recommended Approach	Why	Cost Impact
Visual UI Tweaks	Cursor Composer	Inline diff review and visual feedback accelerate frontend iteration.	Low (Pro subscription)
Deep Refactoring	Claude Code	Opus 4.6 handles complex cross-file dependencies with high reliability.	Medium ($20/mo + API)
Cost-Sensitive Scaling	OpenCode + OmO	Native routing to cheaper models reduces per-task cost significantly.	Low (Free + API costs)
Strict Compliance	Claude Code + Hooks	Built-in hook system enforces quality gates automatically.	Medium
Multi-Provider Strategy	OpenCode	Supports 75+ providers; avoids dependency on a single vendor.	Variable

Configuration Template

Use this template to bootstrap your workflow configuration. Adapt the models and paths to your environment.

{
  "workflow": {
    "name": "fullstack-orchestrator",
    "version": "1.0.0",
    "providers": {
      "anthropic": { "env_var": "ANTHROPIC_API_KEY" },
      "openai": { "env_var": "OPENAI_API_KEY" },
      "google": { "env_var": "GOOGLE_API_KEY" }
    },
    "routing": {
      "default": "claude-sonnet-4",
      "rules": [
        { "pattern": "**/*.css", "model": "gpt-4o-mini" },
        { "pattern": "**/*.test.{ts,tsx}", "model": "gemini-flash-2" },
        { "pattern": "**/Migrations/**", "model": "claude-opus-4.6" }
      ]
    },
    "context": {
      "file": "AGENTS.md",
      "max_tokens": 12000,
      "strategy": "semantic_chunking"
    },
    "hooks": {
      "pre_commit": "npm run lint && dotnet test",
      "post_edit": "npm run type-check"
    }
  }
}

Quick Start Guide

1. Initialize Configuration: Create ai-workflow.config.json in your project root using the template above. Update provider keys and routing rules.

2. Generate Context File: Run npx ai-context-gen --output AGENTS.md to scaffold your context file. Review and customize domain rules and commands.

3. Install Hooks: Execute npx husky install and add the pre-commit script from the Core Solution to enforce quality gates.

4. Verify Routing: Run a test task: npx ai-agent --task "Add a comment to src/utils/helpers.ts" --dry-run. Check logs to confirm the correct model was selected.

5. Start Development: Launch your preferred agent interface. The routing configuration and context file will automatically guide the workflow. Monitor token usage via your provider dashboard.