Legacy Modernizer

Legacy Modernizer — Legacy Code Modernization Pipeline

An agent team collaborates to perform analysis -> refactoring strategy -> migration -> verification of legacy code.

Execution Mode

Agent Team — 5 members communicate directly via SendMessage and cross-validate each other.

Agent Composition

Workflow

Phase 1: Preparation (Performed directly by Orchestrator)

1. Extract from user input:
   • Target Code/System: Codebase or system information to modernize
   • Target Architecture (optional): Desired technology stack/patterns to migrate to
   • Constraints (optional): Downtime tolerance, budget, timeline
   • Existing Documentation (optional): Architecture documents, analysis reports, etc.
2. Create _workspace/ directory at the project root
3. Organize input and save to _workspace/00_input.md
4. If existing files are available, copy them to _workspace/ and skip the corresponding Phase
5. Determine execution mode based on the scope of the request (see "Modes by Task Scale" below)

Phase 2: Team Assembly and Execution

Inter-team Communication Flow:

• analyzer completes -> delivers tech debt, hotspots, and dependencies to strategist; delivers tech stack and business logic to engineer; delivers current coverage to tester
• strategist completes -> delivers roadmap and migration mapping to engineer; delivers Phase completion criteria to tester
• engineer completes -> delivers Before/After and verification points to tester
• tester completes -> requests fixes from engineer if regressions are found
• reviewer cross-validates all deliverables. When RED Must Fix items are found, requests fixes from the relevant agent -> rework -> re-verification (up to 2 times)

Phase 3: Integration and Final Deliverables

1. Check all files in _workspace/
2. Verify that all RED Must Fix items from the review report have been addressed
3. Report the final summary to the user

Modes by Task Scale

Leveraging Existing Files: If the user provides analysis reports, strategy documents, etc., the corresponding step is skipped.

Data Transfer Protocol

File naming convention: {order}_{agent}_{deliverable}.{extension}

Error Handling

Test Scenarios

Normal Flow

Prompt: "Modernize a legacy web app based on jQuery + Express.js to React + NestJS" Expected Result:

• Analysis: jQuery dependency mapping, Express route structure analysis, technical debt inventory
• Strategy: Strangler Fig pattern, frontend-first migration roadmap
• Migration: jQuery -> React component transformation, Express -> NestJS controller transformation
• Testing: DOM manipulation behavior preservation, API compatibility, performance comparison
• Review: Full consistency verification across all items

Existing File Utilization Flow

Prompt: "Create a refactoring strategy based on this analysis report" + analysis report attached Expected Result:

• Copy existing report to _workspace/01_legacy_analysis.md
• Strategy mode: only strategist + reviewer deployed
• analyzer is skipped

Error Flow

Prompt: "Refactor this code" (only code snippet provided, no full context) Expected Result:

• Start in analysis mode, perform inference-based analysis with limited information
• Note in report: "Partial code-based analysis — full system context unverified"
• Ask user for additional information if needed

Agent Extension Skills