---

name: start description: Use when starting reverse engineering on an unfamiliar codebase to identify layers, patterns, and structure before detailed analysis allowed-tools:

• Read
• Grep
• Glob
• Bash(git:, mkdir:, ls:*)
• Write(docs/unwind/**)
• Edit(docs/unwind/**)

---

Discovering Architecture

Overview

Dispatch a subagent to systematically explore a codebase and identify its architectural layers, technology choices, and structure. The subagent produces a machine-parseable architecture document that drives downstream layer-by-layer analysis.

Output: docs/unwind/architecture.md

When to Use

• Starting work on an unfamiliar codebase
• Onboarding to a new project
• Before planning a migration or major refactor
• Beginning a security audit or code review

The Process

Step 1: Gather Repository Information

Run these commands FIRST to get git info for source linking:

git remote get-url origin 2>/dev/null
git branch --show-current 2>/dev/null

Parse the remote URL:

• SSH format: git@github.com:owner/repo.git → https://github.com/owner/repo
• HTTPS format: https://github.com/owner/repo.git → https://github.com/owner/repo
• If no remote: use local type with null URL

Build the repository info block:

repository:
  type: github|gitlab|bitbucket|local
  url: https://github.com/owner/repo  # or null if local
  branch: main                         # or null if local
  link_format: https://github.com/owner/repo/blob/main/{path}#L{start}-L{end}

Step 2: Check for Existing Documentation

Check if docs/unwind/architecture.md exists:

Glob: docs/unwind/architecture.md

• If exists: Pass to subagent as "previous analysis" for refresh mode
• If not: Fresh discovery

Step 3: Dispatch Discovery Subagent

Dispatch an Explore subagent for fast codebase analysis. Note: Explore cannot write files, so you will write the output in Step 4.

Include the repository info from Step 1 in the prompt:

Task(subagent_type="Explore")
  description: "Discover codebase architecture"
  prompt: |
    [See Subagent Prompt below]

    ## Repository Information (already gathered)
    [paste the repository yaml block from Step 1]

The Explore agent should return the complete architecture document content as its output.

Step 4: Write the Architecture Document

When the Explore subagent completes with the document content:

1. Create the output directory:

   mkdir -p docs/unwind
   

2. Write the content to docs/unwind/architecture.md using the Write tool

3. Verify the file was created

Step 5: Present Results and Prompt User

After the subagent completes, present the results to the user:

## Architecture Discovery Complete

I've analyzed the codebase and created the architecture document.

**Output:** `docs/unwind/architecture.md`

### Summary
[Include the summary from the subagent - framework, layers detected, etc.]

### Detected Layers
[List layers with their confidence levels]

### Next Steps

Would you like me to:
1. **Continue with layer analysis** - Run `unwind:unwinding-codebase` to dispatch specialist subagents for each layer
2. **Review the architecture document first** - Open `docs/unwind/architecture.md` to verify the detection is accurate

[Use AskUserQuestion to let them choose]

Important: Always give the user the option to review before proceeding. The architecture document drives all subsequent analysis, so accuracy matters.

---

Subagent Prompt

Use this prompt when dispatching the discovery subagent:

Explore this codebase to identify its architectural layers and structure.

## Your Task

Systematically explore the codebase and return the architecture document content. The main agent will write the file.

**Repository information has already been gathered and will be provided to you.** Use the provided `repository.link_format` for all source links.

## Phase 1: Project Identification

Identify the technology stack by looking for:

**Build System:**
- `package.json` → Node.js/JavaScript
- `pom.xml` / `build.gradle` → Java
- `requirements.txt` / `pyproject.toml` → Python
- `go.mod` → Go
- `Cargo.toml` → Rust
- `*.csproj` → .NET

**Framework:** Check dependencies for Spring Boot, Django, Express, Rails, Next.js, etc.

**Database:** Look for connection strings, ORM config, migration directories.

## Phase 2: Directory Mapping

Scan source directories and map to layers:

| Directory Pattern | Likely Layer |
|-------------------|--------------|
| `repository/`, `dao/`, `data/` | Database |
| `model/`, `entity/`, `domain/` | Domain Model |
| `service/`, `usecase/`, `application/` | Service Layer |
| `controller/`, `api/`, `rest/`, `graphql/` | API Layer |
| `messaging/`, `events/`, `queue/`, `kafka/` | Messaging |
| `components/`, `pages/`, `views/`, `ui/` | Frontend |

## Phase 3: Confidence Assessment

For each layer, assess confidence:
- **High**: Clear directory structure, multiple files, consistent naming
- **Medium**: Some indicators but mixed patterns
- **Low**: Minimal evidence
- **Not Detected**: No evidence found

## Phase 4: Cross-Cutting Concerns

Identify aspects spanning multiple layers:
- Authentication/Authorization
- Logging
- Error Handling
- Caching
- Validation

## Phase 5: Return Architecture Document

**DO NOT attempt to write the file** - you don't have write permissions. Instead, return the complete architecture document content in your response. The main agent will write it to `docs/unwind/architecture.md`.

Return the document in this exact format:

```markdown
# Architecture Discovery: [Project Name]

> **For Claude:** REQUIRED SUB-SKILL: Use unwind:unwinding-codebase to analyze each layer.

## Discovery Metadata

- **Generated:** [ISO timestamp]
- **Project Root:** [path]
- **Framework:** [detected framework]
- **Language:** [primary language]

## Repository Information

```yaml
repository:
  type: github|gitlab|bitbucket|local
  url: https://github.com/owner/repo  # or null if local
  branch: main                         # or null if local
  link_format: https://github.com/owner/repo/blob/main/{path}#L{start}-L{end}

For all downstream agents: Use link_format to create source links. Replace {path}, {start}, {end} with actual values.

Layer Configuration

layers:
  database:
    status: detected|not_detected
    confidence: high|medium|low
    entry_points:
      - path/to/data/layer/
    dependencies: []

  domain_model:
    status: detected|not_detected
    confidence: high|medium|low
    entry_points:
      - path/to/domain/
    dependencies: [database]

  service_layer:
    status: detected|not_detected
    confidence: high|medium|low
    entry_points:
      - path/to/services/
    dependencies: [domain_model]

  api:
    status: detected|not_detected
    confidence: high|medium|low
    entry_points:
      - path/to/controllers/
    dependencies: [service_layer]

  messaging:
    status: detected|not_detected
    confidence: high|medium|low
    entry_points: []
    dependencies: [service_layer]

  frontend:
    status: detected|not_detected
    confidence: high|medium|low
    entry_points: []
    dependencies: [api]

cross_cutting:
  authentication:
    touches: [api, service_layer]
    entry_points:
      - path/to/security/

Database Layer

Status: [Detected/Not Detected] | Confidence: [High/Medium/Low]

Entry Points:

• [directories/files]

Initial Observations:

• [What you found - technology, patterns, notable aspects]

---

[Repeat for each layer with status != not_detected]

---

Cross-Cutting Concerns

Authentication

Touches: [layers] [Observations]

[Other concerns...]

---

Discovery Notes

• [Unknowns, questions, areas needing clarification]

{REFRESH_CONTEXT}

## Output

After creating the architecture document, provide a brief summary:
- Project type and framework
- Which layers were detected (with confidence)
- Any notable findings or concerns

---

Refresh Mode Context

If previous architecture.md exists, add this to the subagent prompt:

## Previous Analysis

A previous architecture analysis exists. Compare the current codebase state to this previous analysis and:

1. Note any changes in the `## Changes Since Last Discovery` section
2. Update layer status/confidence if changed
3. Add new entry points discovered
4. Remove entry points that no longer exist
5. Update the `last_analyzed` timestamp

Previous analysis:
[CONTENTS OF EXISTING architecture.md]

---

Layer Detection Reference

Database Layer Indicators

• Directories: repository/, dao/, data/, persistence/
• Files: *Repository.java, *_repository.py, *.repo.ts
• ORM: Hibernate, SQLAlchemy, Prisma, TypeORM, Sequelize
• Migrations: Flyway, Liquibase, Alembic, Prisma migrations

Domain Model Indicators

• Directories: domain/, model/, entity/, entities/
• Files: *Entity.java, models.py, *.entity.ts
• Patterns: @Entity, class Model, aggregates, value objects

Service Layer Indicators

• Directories: service/, services/, usecase/, application/
• Files: *Service.java, *_service.py, *.service.ts
• Patterns: @Service, @Transactional, business logic methods

API Layer Indicators

• Directories: controller/, api/, rest/, routes/, graphql/
• Files: *Controller.java, views.py, *.controller.ts
• Patterns: @RestController, @router, route definitions

Messaging Layer Indicators

• Directories: messaging/, events/, queue/, kafka/, rabbitmq/
• Files: *Listener.java, *Consumer.py, *.handler.ts
• Configs: Kafka, RabbitMQ, SQS configuration

Frontend Layer Indicators

• Directories: components/, pages/, views/, ui/, src/app/
• Files: *.tsx, *.vue, *.component.ts
• Configs: React, Vue, Angular, Next.js, Nuxt