mainframe-modernization-and-data-offload

mainframe-modernization-and-data-offload is a skill for Claude Code, Codex from vaquarkhan/data-engineering-agent-skills. It costs 67 tokens per session (671 once invoked), scanned A, original, MIT.

A guide to moving data from mainframe systems such as COBOL, JCL, VSAM, IMS, or DB2 for z/OS into modern storage, streaming systems, or APIs. It also covers running old and new systems together during the transition.

In plain words
What is it for?
Use it to plan data offloads, replication, contract mapping, phased cutovers, replay, and checks between mainframe and modern systems.
Why use it?
It helps teams handle legacy record formats, batch schedules, restart behavior, dependencies, and reconciliation instead of treating migration as simple file transfer.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to plan data offloads, replication, contract mapping, phased cutovers, replay, and checks between mainframe and modern systems.

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Install with agentmods
npx agentmods add skills/vaquarkhan/data-engineering-agent-skills/mainframe-modernization-and-data-offload
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.

Any agent
npx skills add vaquarkhan/data-engineering-agent-skills --skill mainframe-modernization-and-data-offload
Clone the repo
git clone --depth 1 https://github.com/vaquarkhan/data-engineering-agent-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

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README.md
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Your own site
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Your own site · 80×15
<a href="https://agentmods.dev/skills/vaquarkhan/data-engineering-agent-skills/mainframe-modernization-and-data-offload"><img src="https://agentmods.dev/badge/skills/vaquarkhan/data-engineering-agent-skills/mainframe-modernization-and-data-offload.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 67 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 671 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00067 $0.00671
Opus 5 $0.00034 $0.00336
Sonnet 5 $0.00013 $0.00134
Haiku 4.5 $0.00007 $0.00067

Measured 8d ago against content hash c9e97122bec6, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

mainframe-modernization-and-data-offload 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 8d 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.

skills/mainframe-modernization-and-data-offload/SKILL.md · 79 lines

How it starts

The opening of the file, as written. The whole thing — 79 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Mainframe Modernization And Data Offload

Overview

Use this skill when a modernization effort involves mainframe systems, batch schedules, and legacy data structures rather than only modern ETL tooling. It helps agents design offload, replication, contract mapping, coexistence, reconciliation, and cutover paths for mainframe-origin data.

When to Use

  • modernizing COBOL, JCL, VSAM, IMS, or DB2 for z/OS data flows
  • offloading mainframe data to lakes, warehouses, or downstream APIs
  • mapping copybooks and legacy record layouts into modern contracts
  • designing coexistence between batch mainframe outputs and modern platforms
  • planning phased cutover, replay, and reconciliation for legacy estates

Do not treat mainframe modernization as only a transport problem. Semantics, batch windows, restart behavior, and operational dependencies matter.

Workflow

  1. Inventory the legacy behavior. Capture:

    • source systems
    • copybooks or record layouts
    • batch schedules
    • restart and rerun behavior
    • downstream consumers
  2. Define the modernization target. Decide:

    • offload versus replication versus coexistence
    • target storage and serving platforms
    • contract and schema mapping
    • latency and batch-window expectations
  3. Design parity and reconciliation. Require:

    • source-to-target field mapping
    • control totals and reconciliation
    • correction and replay behavior
    • cutover acceptance criteria
  4. Plan coexistence and cutover. Cover:

    • dual-run period
    • dependent consumer migrations
    • backout plan
    • ownership and incident routing during cutover
  5. Validate operational readiness. Check restart, failure recovery, performance windows, and support responsibilities before moving critical consumers.

Common Rationalizations

Rationalization Reality
"We only need to copy the files out." Mainframe jobs often encode business rules, restart behavior, and sequencing that must be preserved or redesigned.
"Schema mapping is straightforward once we read the copybook." Field semantics, packed decimals, dates, and code tables often require careful domain translation.
"We can switch consumers after one successful run." Mainframe modernization usually needs parity evidence and a deliberate coexistence period.

Read the full file on GitHub · 79 lines

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. 8d ago First seen · 79 lines · 67 tokens per session scan A c9e97122bec6

Subscribe to this mod's changes

mainframe-modernization-and-data-offload is a skill published in the GitHub repository vaquarkhan/data-engineering-agent-skills (45 stars, last pushed 3mo ago), licensed MIT. It adds 67 tokens to every session and 671 once invoked, about $0.0003 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 2026-09-03.