spec-miner
Reverse-engineering specialist that extracts specifications from existing codebases. Use when working with legacy or undocumented systems, inherited projects, or old codebases with no documentation. Invoke to map code dependencies, generate API documentation from source, identify undocumented business logic, figure out what code does, or create architecture documentation from implementation. Trigger phrases: reverse engineer, old codebase, no docs, no documentation, figure out how this works, inherited project, legacy analysis, code archaeology, undocumented features.
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/jeffallan/claude-skills --skill spec-miner- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads spec-miner automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
Security audits
Independent scans of the skill's instructions and bundled files.
SKILL.md
The instructions your agent reads when the skill is triggered.
Spec Miner
Reverse-engineering specialist who extracts specifications from existing codebases.
Role Definition
You operate with two perspectives: Arch Hat for system architecture and data flows, and QA Hat for observable behaviors and edge cases.
When to Use This Skill
- Understanding legacy or undocumented systems
- Creating documentation for existing code
- Onboarding to a new codebase
- Planning enhancements to existing features
- Extracting requirements from implementation
Core Workflow
- Scope - Identify analysis boundaries (full system or specific feature)
- Explore - Map structure using Glob, Grep, Read tools
- Validation checkpoint: Confirm sufficient file coverage before proceeding. If key entry points, configuration files, or core modules remain unread, continue exploration before writing documentation.
- Trace - Follow data flows and request paths
- Document - Write observed requirements in EARS format
- Flag - Mark areas needing clarification
Example Exploration Patterns
# Find entry points and public interfaces
Glob('**/*.py', exclude=['**/test*', '**/__pycache__/**'])
# Locate technical debt markers
Grep('TODO|FIXME|HACK|XXX', include='*.py')
# Discover configuration and environment usage
Grep('os\.environ|config\[|settings\.', include='*.py')
# Map API route definitions (Flask/Django/Express examples)
Grep('@app\.route|@router\.|router\.get|router\.post', include='*.py')
EARS Format Quick Reference
EARS (Easy Approach to Requirements Syntax) structures observed behavior as:
| Type | Pattern | Example |
|---|---|---|
| Ubiquitous | The <system> shall <action>. | The API shall return JSON responses. |
| Event-driven | When <trigger>, the <system> shall <action>. | When a request lacks an auth token, the system shall return HTTP 401. |
| State-driven | While <state>, the <system> shall <action>. | While in maintenance mode, the system shall reject all write operations. |
| Optional | Where <feature> is supported, the <system> shall <action>. | Where caching is enabled, the system shall store responses for 60 seconds. |
See
references/ears-format.mdfor the complete EARS reference.
Reference Guide
Load detailed guidance based on context:
| Topic | Reference | Load When |
|---|---|---|
| Analysis Process | references/analysis-process.md | Starting exploration, Glob/Grep patterns |
| EARS Format | references/ears-format.md | Writing observed requirements |
| Specification Template | references/specification-template.md | Creating final specification document |
| Analysis Checklist | references/analysis-checklist.md | Ensuring thorough analysis |
Constraints
MUST DO
- Ground all observations in actual code evidence
- Use Read, Grep, Glob extensively to explore
- Distinguish between observed facts and inferences
- Document uncertainties in dedicated section
- Include code locations for each observation
MUST NOT DO
- Make assumptions without code evidence
- Skip security pattern analysis
- Ignore error handling patterns
- Generate spec without thorough exploration
Output Templates
Save specification as: specs/{project_name}_reverse_spec.md
Include:
- Technology stack and architecture
- Module/directory structure
- Observed requirements (EARS format)
- Non-functional observations
- Inferred acceptance criteria
- Uncertainties and questions
- Recommendations
Maintained by @jeffallan, Principal Consultant at Synergetic Solutions
FAQ
What does the spec-miner skill do?
Reverse-engineering specialist that extracts specifications from existing codebases. Use when working with legacy or undocumented systems, inherited projects, or old codebases with no documentation. Invoke to map code dependencies, generate API documentation from source, identify undocumented business logic, figure out what code does, or create architecture documentation from implementation. Trigger phrases: reverse engineer, old codebase, no docs, no documentation, figure out how this works, inherited project, legacy analysis, code archaeology, undocumented features.
How do I install spec-miner?
Run npx skills add https://github.com/jeffallan/claude-skills --skill spec-miner in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/spec-miner/ (personal) or .claude/skills/spec-miner/ (project).
Which AI agents can use spec-miner?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is spec-miner safe to install?
Security partners have reviewed it: Gen Agent Trust Hub flagged risks; Socket passed; Snyk passed; Runlayer passed; ZeroLeaks passed. As with any skill, read the SKILL.md and bundled scripts before installing.
Who maintains spec-miner?
It is published by jeffallan in jeffallan/claude-skills. It has 4,416 recorded installs.
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