migration-mapping

A migration traceability tool that links files in an old programming language to the files implementing their functionality in a new language. Traceability means being able to follow each old part into the replacement system.

In plain words
What is it for?
Use it to map source files such as COBOL files to target files such as Java files, including one-to-many and many-to-many relationships, and save the result as JSON.
Why use it?
It exposes missing replacements and makes it easier to check whether a migration is complete and correctly documented.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/openhands/extensions/migration-mapping
Any agent
npx skills add OpenHands/extensions --skill migration-mapping
Clone the repo
git clone --depth 1 https://github.com/OpenHands/extensions

Made for: Claude Code, Codex.

Per session 28 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 520 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00028 $0.00520
Opus 5 $0.00014 $0.00260
Sonnet 5 $0.00006 $0.00104
Haiku 4.5 $0.00003 $0.00052

Measured 2d ago against content hash 6b65c7e6b155, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

migration-mapping scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

plugins/migration-scoring/skills/migration-mapping/SKILL.md · 73 lines

What it actually says

Create a mapping from source language files (e.g., COBOL) to target language files (e.g., Java) to document which target files implement the functionality of each source file.

Task

Examine all source language files and identify the corresponding target language files that implement the same functionality. This mapping is essential for:

  • Migration quality evaluation
  • Traceability documentation
  • Gap analysis

Output Format

Save the mapping as a JSON file with this structure:

{
  "source_file_1.cbl": ["target_file_a.java", "target_file_b.java"],
  "source_file_2.cbl": ["target_file_c.java"],
  "source_file_3.cbl": []
}

Rules

  1. Many-to-many mapping: A source file may map to multiple target files, and a target file may implement logic from multiple source files
  2. Complete coverage: EVERY source file must appear as a key in the mapping
  3. Complete target coverage: EVERY target file should appear as a value at least once
  4. Empty arrays: If a source file has no corresponding target implementation, use an empty array []
  5. Incremental: If a mapping file already exists, update it rather than replacing it

How to Identify Mappings

Look for:

  • Matching class/program names
  • Similar function/paragraph names
  • Matching business logic patterns
  • Comments referencing source files
  • Import/include statements
  • Data structure similarities

Example

For a COBOL-to-Java migration:

{
  "CALC001.cbl": ["InvoiceCalculator.java", "TaxCalculator.java"],
  "CUST002.cbl": ["CustomerService.java", "CustomerRepository.java"],
  "UTIL003.cbl": ["StringUtils.java"],
  "SCREEN001.cbl": []
}

Note: SCREEN001.cbl maps to nothing because UI code was not migrated.

Verification

After creating the mapping:

  • Every source file is a key
  • No duplicate keys
  • Target files are relative paths from project root
  • JSON is valid and well-formatted
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 73 lines · 28 tokens per session scan A 6b65c7e6b155

Subscribe to this mod's changes

migration-mapping is a skill published in the GitHub repository OpenHands/extensions (137 stars, last pushed 4d ago), licensed MIT. It adds 28 tokens to every session and 520 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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