vdt-fix

name	vdt:fix
description	Fix bugs with single-agent reasoning loop. Demonstrates Pattern 1: Single Agent Architecture.
user-invocable	true
when_to_use	Invoke when there is a concrete bug to fix. One-shot reasoning loop.
category	utilities
keywords	["bugfix","single-agent","reasoning-loop","pattern-1"]
argument-hint	[error description]
metadata	{"author":"vdt-demo","version":"1.0.0"}

Fix — Single Agent Reasoning Loop (Pattern 1)

One-shot bug fix using a reasoning loop: Read → Reason → Fix → Test → Done.

Usage

/vdt:fix "TypeError: Cannot read property 'email' of null at auth/login.ts:45"

Workflow

Step 1: Read

• Read the file at the error location
• Read related test files
• Understand the surrounding context

Step 2: Reason

• Analyze the root cause (NOT just the symptom)
• Form hypothesis: "user can be null when not found in DB, but code assumes it exists"
• Identify the minimal fix that resolves the issue

Step 3: Fix

• Apply targeted edit (minimal change, maximum correctness)
• Write a regression test if none exists
• Delegate to debugger agent if root cause is unclear

Step 4: Test

• Run npm test to verify fix
• Confirm no regressions introduced
• If test passes → DONE

Key Principle

This is a SINGLE agent with a reasoning loop — no delegation to multiple agents, no retry loops, no conditional routing. Just: read, think, fix, verify.

Demo Annotation

🧠 Reason: "I need to read the file to understand context"
📖 Read: src/auth/login.ts — see null access at line 45
🧠 Reason: "user can be null, need early return with 401"
🔧 Fix: Add null check before accessing user.email
🧪 Test: npm test → All pass ✅