legacy-code-interpreter

// Understand and document legacy code behavior through deep analysis and behavior characterization

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stars:384

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updated:March 4, 2026

SKILL.mdreadonly

SKILL.md Frontmatter

namelegacy-code-interpreter

descriptionUnderstand and document legacy code behavior through deep analysis and behavior characterization

allowed-toolsBash,Read,Write,Grep,Glob,Edit

Legacy Code Interpreter Skill

Deep analysis and interpretation of legacy code to understand undocumented behavior, extract business logic, and characterize system functionality.

Purpose

Enable legacy code understanding for:

Business logic extraction
Undocumented feature discovery
Behavior characterization
Migration planning
Knowledge preservation

Capabilities

1. Business Logic Extraction

Parse conditional logic
Extract calculation formulas
Identify validation rules
Document decision trees

2. Undocumented Feature Discovery

Find hidden functionality
Identify feature flags
Discover Easter eggs
Map admin features

3. Control Flow Analysis

Trace execution paths
Map state machines
Identify loops and recursion
Document entry points

4. Data Flow Tracking

Trace data transformations
Map input to output
Identify side effects
Document state changes

5. Side Effect Identification

Find external calls
Identify I/O operations
Map database operations
Document messaging

6. Behavior Characterization

Create behavior summaries
Generate pseudo-code
Document edge cases
Map error handling

Tool Integrations

Tool	Purpose	Integration Method
Understand (SciTools)	Deep analysis	CLI / API
Lattix	Architecture analysis	CLI
CodeScene	Behavioral analysis	API
Sourcetrail	Code exploration	CLI
ast-grep	Pattern matching	MCP / CLI

Output Schema

{
  "analysisId": "string",
  "timestamp": "ISO8601",
  "interpretation": {
    "businessLogic": [
      {
        "name": "string",
        "location": "string",
        "description": "string",
        "pseudoCode": "string",
        "inputs": [],
        "outputs": [],
        "sideEffects": []
      }
    ],
    "controlFlow": {
      "entryPoints": [],
      "stateMachines": [],
      "criticalPaths": []
    },
    "dataFlow": {
      "transformations": [],
      "stateChanges": []
    },
    "undocumented": []
  }
}

Integration with Migration Processes

legacy-codebase-assessment: Primary interpretation tool
migration-planning-roadmap: Knowledge source

Related Skills

static-code-analyzer: Structural analysis
knowledge-extractor: Documentation mining

Related Agents

legacy-system-archaeologist: Uses for excavation