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description: Start StackShift reverse engineering process - analyzes codebase, auto-detects application type (monorepo service, Nx app, etc.), and guides through 6-gear transformation to spec-driven development. Choose Greenfield (tech-agnostic for migration) or Brownfield (tech-prescriptive for maintenance).
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# StackShift: Reverse Engineering Toolkit

**Start the 6-gear reverse engineering process**

Transform your application into a fully-specified, spec-driven codebase.

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## Auto-Detection

StackShift will automatically detect your widget/module type:

- **service-*** → Monorepo Service (in services/ directory)
- **shared-*** → Shared Package (in packages/ directory)
- **Nx project in apps/ → Nx Application
- **Turborepo package → Turborepo Package
- **Other** → Generic application (user chooses Greenfield or Brownfield)

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## Quick Start

**Just run the analyze skill to begin:**

```
I want to reverse engineer this application.
```

Or be specific:

```
Analyze this codebase for Greenfield migration to Next.js.
```

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## The 6-Gear Process

Once analysis starts, you'll shift through these gears:

### 🔍 Gear 1: Analyze
- Auto-detect widget/module type
- Detect tech stack and architecture
- Assess completeness
- Choose route (or auto-selected)
- Configure workflow options

### 🔄 Gear 2: Reverse Engineer
- Extract comprehensive documentation (8-9 files)
- Business logic extraction
- For monorepo: Include shared packages
- 
- For Greenfield: Tech-agnostic requirements
- For Brownfield: Tech-prescriptive implementation

### 📋 Gear 3: Create Specifications
- Initialize GitHub Spec Kit (`.specify/`)
- Create Constitution (project principles)
- Generate feature specifications
- Create implementation plans
- Install `/speckit.*` slash commands

### 🔎 Gear 4: Gap Analysis
- **Greenfield:** Validate spec completeness, ask about target stack
- **Brownfield:** Run `/speckit.analyze`, find implementation gaps
- Identify clarification needs
- Prioritize features (P0/P1/P2/P3)
- Create implementation roadmap

### ✨ Gear 5: Complete Specification
- Resolve `[NEEDS CLARIFICATION]` markers
- Interactive Q&A session
- Use `/speckit.clarify` for structured clarification
- Finalize all specifications
- Ensure no ambiguities remain

### 🚀 Gear 6: Implement
- **Greenfield:** Build NEW app in chosen tech stack
- **Brownfield:** Fill gaps in existing implementation
- Use `/speckit.tasks` for task breakdown
- Use `/speckit.implement` for execution
- Validate with `/speckit.analyze`

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## Routes Available

| Route | Auto-Detect | Purpose |
|-------|-------------|---------|
| **greenfield** | Generic app | Extract business logic, rebuild in new stack |
| **brownfield** | Generic app | Spec existing codebase, manage with Spec Kit |
| **monorepo-service** | services/* | Extract service + shared packages |
| **nx-app** | has nx.json | Extract Nx app + project config |



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## Workflow Options

**Manual Mode:**
- Review each gear before proceeding
- You control the pace
- Good for first-time users

**Cruise Control:**
- Shift through all gears automatically
- Hands-free execution
- Good for experienced users or overnight runs
- Configure: clarifications strategy, implementation scope

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## Additional Commands

After completing Gears 1-6:

- **`/stackshift.modernize`** - Brownfield Upgrade Mode (dependency modernization)
- **`/speckit.*`** - GitHub Spec Kit commands (auto-installed in Gear 3)

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## Prerequisites

- Git repository with code to analyze
- Claude Code with plugin support
- ~2-4 hours for complete process (or use Cruise Control)

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## Examples

**Monorepo migration:**
```
I want to reverse engineer ws-vehicle-details for migration to Next.js.
```

**Legacy app spec creation:**
```
Analyze this Java Spring app and create specifications for ongoing management.
```

**Nx application extraction:**
```
Analyze this V9 Velocity widget and extract the business logic.
```

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## Starting Now

**I'm now going to analyze this codebase and begin the StackShift process!**

Here's what I'll do:

1. ✅ Auto-detect application type (monorepo-service, nx-app, generic, etc.)
2. ✅ Detect tech stack and architecture
3. ✅ Assess completeness
4. ✅ Determine or ask for route
5. ✅ Set up workflow configuration
6. ✅ Begin Gear 1: Analyze

Let me start by analyzing this codebase... 🚗💨

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**Now beginning StackShift Gear 1: Analyze...**