migration-advisor

migration-advisor is a skill for Claude Code, Codex from AdamBien/airails. It costs 144 tokens per session (1,230 once invoked), scanned A, original, MIT.

A first assessment step for moving an old software system to newer technology. It examines simple repository, Git history, and running-system signals, then recommends a migration route and follow-up steps.

In plain words
What is it for?
Use it to assess an unfamiliar legacy repository, compare rehosting, replatforming, and rearchitecting, and produce an ordered migration plan.
Why use it?
Legacy migrations can require major architectural choices, such as moving the system as-is, changing its platform, or redesigning it. This creates a reviewable plan before deeper investigation.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: names the AskUserQuestion tool.

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/adambien/airails/migration-advisor
Any agent
npx skills add AdamBien/airails --skill migration-advisor
Clone the repo
git clone --depth 1 https://github.com/AdamBien/airails

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.

agentmods badge for migration-advisor

README.md
[![agentmods](https://agentmods.dev/badge/skills/adambien/airails/migration-advisor.svg)](https://agentmods.dev/skills/adambien/airails/migration-advisor)
Your own site
<a href="https://agentmods.dev/skills/adambien/airails/migration-advisor"><img src="https://agentmods.dev/badge/skills/adambien/airails/migration-advisor.svg" alt="Measured on agentmods" height="20"></a>
Per session 144 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,230 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 5.1 $0.00144 $0.01230
Opus 5 $0.00072 $0.00615
Sonnet 5 $0.00029 $0.00246
Haiku 4.5 $0.00014 $0.00123

Measured 6d ago against content hash b8bdb4ded7d8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

migration-advisor 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 6d 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.

migrations/migration-advisor/SKILL.md · 67 lines

How it starts

The opening of the file, as written. The whole thing — 67 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Migration Advisor

The triage front door. Legacy migration is judgment-heavy and the entry-path choice is a human decision — this skill gathers the cheap signals that inform that choice, recommends a path and a sequence, and hands off. It routes, never executes: every step it recommends is invoked explicitly by a human, and each produces a reviewable artifact.

Stay shallow. The value is finishing in under a minute on a repo you have never seen. Deep vocabulary mining is /concept-extractor; behavior capture is /characterization-tests. Those are steps in the plan, not prerequisites to producing it.

Data Sources

Use whatever is present; state in the plan which were available — a plan built without git or a runnable instance is more heuristic, and must say so.

Repo probe (always)

Read-only counts and pattern hits, never comprehension:

  • Platform / age — build files: javax.* vs jakarta.*, servlet/EJB/JSF/Spring versions, target JDK; or package.json with jQuery/AngularJS/Backbone.
  • Size / shape — module, package, and file counts; LOC order of magnitude; density of *Manager/*Impl/*Util/*Facade names (overengineering signal → concept pipeline pays off; small and clean → rearchitect directly).
  • External dependencies — count and identity of libraries with Java SE or platform equivalents (the replatform/simplifier signal).
  • Test coverage — presence and size of a test source tree (near-zero → characterization must come first; "1:1 lift" is risky).
  • Surfaces — JAX-RS resources, web.xml mappings, queue config, batch jobs; whether a runnable artifact exists (is characterization feasible, on which surface).

Git history (if .git present)

Aggregate git log / shortlog / --numstat, not per-file blame:

  • Liveness — last commit date, commit frequency: frozen (experts likely gone → lean on recorded behavior and async questionnaires) vs. active (strangle alongside ongoing work).
  • Bus factorgit shortlog -sne: contributor count and whether the top authors are recent. Pre-fills the interview's expert-availability question with names.
  • Hotspots — churn per file/package: where behavior is volatile and characterization should concentrate.
  • Temporal coupling — files that change together: empirical evidence that latent structure exists and the carve path will pay off. Note it; do not carve — that is /bc-carver.
  • Code age — old untouched code is safe to lift; recently churned code is where lift risk concentrates.

Read the full file on GitHub · 67 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 6d ago First seen · 67 lines · 144 tokens per session scan A b8bdb4ded7d8

Subscribe to this mod's changes

migration-advisor is a skill published in the GitHub repository AdamBien/airails (48 stars, last pushed yesterday), licensed MIT. It adds 144 tokens to every session and 1,230 once invoked, about $0.0007 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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