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Step 02 of 10 3-6 quarters (yes — this is the longest phase)· advanced

Step 2: Business Rule Extraction (the long phase)

Convert each in-scope COBOL program into a structured catalog of business rules, decision tables, calculations, and edge cases — validated by SMEs. This is usually the longest phase.

What you're doing in this step

For every program in scope, extract the business rules using the cobol-business-rule-extraction template. Run iteratively: auto-extract via tooling, then senior engineers refine, then business analysts validate, then SMEs sign off. Each program produces 30-100 rules plus decision tables, calculation formulas, edge cases, and open questions.

Recommended prompts

Use one of these to do the work in your IDE

Open the template to read it in full. Click Copy prompt to grab it (with your stack values pre-filled where they apply) — then paste into Claude Code, Cursor, or wherever you build.

Primary recommendation varies (per program)

COBOL Business Rule Extraction

Extract business rules from COBOL programs into a structured catalog that survives the migration — even if the original COBOL doesn't.

cobolmainframe

View template

Template· Template reference document

COBOL to Java/.NET Translation Checklist

Pattern-by-pattern translation guide for COBOL constructs to modern Java or .NET equivalents — including the patterns that don't translate.

Use this when: Working through translation patterns alongside the rule extraction (helps surface what each idiom is doing)

coboljavadotnet

View template

Recommended skills

Drop these into Claude Code for this phase

Skills auto-trigger on the right kind of request. Install once; they apply to every prompt that fits.

Skill· Skill 5 min setup

Legacy Code Analyzer Skill

Claude Code skill that reads legacy .NET code (WebForms, VB.NET, classic ASP) and explains what it does — the foundation for any migration.

claude-codedotnet

View skill

Skill· Skill 5 min setup

Migration Planner Skill

Flagship migration skill that walks Claude Code through audit → strategy → slicing → cutover for any legacy system migration.

claude-code

View skill

Recommended MCP configs

Wire these tools into Claude Code first

MCP servers give Claude Code direct access to external systems (Jira, browsers, databases). Configure once.

MCP config· MCP config 5 min setup

Filesystem MCP for Evoke

Pre-configured filesystem MCP server for Claude Code — safe, scoped read/write access to project files.

claude-codemcp

View config

MCP config· MCP config 10 min setup

Confluence MCP for Evoke

Pre-configured Atlassian Confluence MCP server for Claude Code — search, read, and write internal documentation pages from chat.

claude-codemcp

View config

When you're done

Verify these in your own work before moving on

This is a checklist for you to mentally tick off in your repo and IDE — the site doesn't track it, you do.

All in-scope programs have extracted rule catalogs
Rules validated by business analysts
SMEs signed off on critical-path rules
Decision tables built for complex branching
Calculation formulas with rounding rules documented
Edge cases explicit
Cross-program rule duplications identified (same rule, different implementations)
Open questions tracked and assigned

Common pitfalls

What goes wrong at this step

Trying to extract rules from all 800 programs in parallel — sequence by criticality; do the most important first
Skipping business-analyst validation — unvalidated rules will produce a wrong rewrite
Treating extraction as one-shot — iterative refinement is normal; budget for 2-3 passes
Letting SMEs disengage — SME availability is your scarcest resource; lock in commitments
Auto-extracted rules treated as final — tools miss context; human review is non-negotiable
Missing the cross-program patterns — same rule may be implemented 5 different ways across the codebase

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