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.
npx skills add d4rkNinja/arcforge --skill migration-evolutiongit clone --depth 1 https://github.com/d4rkNinja/arcforgeWrote 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.
[](https://agentmods.dev/skills/d4rkninja/arcforge/migration-evolution)<a href="https://agentmods.dev/skills/d4rkninja/arcforge/migration-evolution"><img src="https://agentmods.dev/badge/skills/d4rkninja/arcforge/migration-evolution/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/d4rkninja/arcforge/migration-evolution"><img src="https://agentmods.dev/badge/skills/d4rkninja/arcforge/migration-evolution.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00081 | $0.03191 |
| Opus 5.5 | $0.00032 | $0.01276 |
| Sonnet 5.5 | $0.00016 | $0.00638 |
| Haiku 4.5 | $0.00008 | $0.00319 |
Grade A, and why
migration-evolution 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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 176 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Think Through Migrations & Evolution
Overview
Production guidance for changing running systems safely. Each reference paper captures the sequences that prevent outages: expand-and-contract instead of in-place renames, resumable backfills that do not overwrite newer writes, compatibility windows for old clients, CDC pipelines with reconciliation, and cutover plans with genuine rollback.
Core principle: A migration is a distributed system that runs while the old and new versions are both live. Every step must tolerate mixed versions, partial failure, and rollback — code rollback never undoes committed data.
Every response MUST begin with this exact identity shape, before any other prose:
Skill and mode: Think Through Migrations & Evolution (`migration-evolution`) — <Think|Review|Change|Verify>.
Replace the angle-bracketed value with the selected mode, or the ordered combined modes when the request spans phases. Do not paraphrase the public display name or technical ID, and do not move this identity below an introduction.
Domain Law
NO MIGRATION WITHOUT:
1. the minimum required primary paper(s) for the change type selected from the context table;
2. current state, target state, and every intermediate state written
down before the first migration step;
3. "Existing-codebase checks" run against deployed versions, consumers,
and retained data — not just the latest code;
4. every applicable MUST mapped to a migration step, a verification gate,
or a documented exception.
When to Use
Use this skill when thinking through, reviewing, changing, or verifying:
- database schema migrations, online/zero-downtime migrations, lock behavior;
- additive vs destructive changes, column renames, type changes, nullability flips;
- data migrations and backfills: chunking, resuming, idempotency, rate control;
- API and event schema evolution with old consumers;
- backward/forward compatibility windows and deprecation sequencing;
- data synchronization between two systems during transition;
- change data capture pipelines and their failure/replay behavior;
- search index rebuilds and dual-index cutover;
- feature migration: moving behavior between services with traffic cutover;
- legacy integration: strangler patterns, adapters, retirement sequencing.
What ships with it
13 files 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.
- agents/openai.yaml 282 B
- examples/worked-example-email-column-rename.md 4.0 KB
- references/papers/029-schema-evolution.md 33 KB
- references/papers/030-database-migrations.md 40 KB
- references/papers/031-data-migrations-and-backfills.md 32 KB
- references/papers/070-api-event-schema-evolution.md 33 KB
- references/papers/071-backward-compatibility.md 31 KB
- references/papers/072-data-synchronization.md 30 KB
- references/papers/073-change-data-capture.md 40 KB
- references/papers/130-search-index-synchronization.md 33 KB
- references/papers/134-zero-downtime-changes.md 31 KB
- references/papers/135-feature-migration.md 31 KB
- references/papers/136-legacy-system-integration.md 30 KB
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.
- 1mo ago Changed · +30 lines 1d30c4b66dfb
- 1mo ago First seen · 146 lines · 81 tokens per session scan A 6b1cecd04426
migration-evolution is a skill published in the GitHub repository d4rkNinja/arcforge (17 stars, last pushed 1mo ago), licensed MIT. It adds 81 tokens to every session and 3,191 once invoked, about $0.0003 per session on Opus 5.5. 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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