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 agentmods add rules/muraaano/cursor-project-rules-on-rails/migrationgit clone --depth 1 https://github.com/muraaano/cursor-project-rules-on-railsWrote 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/rules/muraaano/cursor-project-rules-on-rails/migration)<a href="https://agentmods.dev/rules/muraaano/cursor-project-rules-on-rails/migration"><img src="https://agentmods.dev/badge/rules/muraaano/cursor-project-rules-on-rails/migration.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00000 | $0.00442 |
| Opus 5 | $0.00000 | $0.00221 |
| Sonnet 5 | $0.00000 | $0.00088 |
| Haiku 4.5 | $0.00000 | $0.00044 |
Grade A, and why
migration 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.
What it actually says
DBマイグレーションの実装規約
全般
- マイグレーションファイルは
db/migrateに配置する - マイグレーションファイルの命名規則は
YYYYMMDDHHMMSS_create_table_name.rbとする - マイグレーションファイルは、操作するテーブルごとにファイルを分ける（1ファイルで1つのテーブルを作成する）
- 過去のマイグレーションファイルは修正しないこと
- データ構造の変更が必要な場合は、新しいマイグレーションファイルを作成する
- マイグレーションファイルのバージョンは、現在使用しているRailsのバージョンに合わせること（例: Rails 7.2を使用している場合は
ActiveRecord::Migration[7.2]と指定）
カラム定義
カラム名
- Date型のカラムは末尾に
_dateをつけること（例：planned_date） - DateTime型のカラムは末尾に
_atをつけること（例：planned_at）
外部キー
referencesを使用する場合は、明示的なインデックスの追加は不要referencesが自動的にインデックスを作成するため
- 外部キーを持つテーブルは、参照先のテーブルが先に作成されていることを確認すること
- マイグレーションファイルの番号で制御すること
コメント
- カラムには論理名（日本語）をコメントとして追加する。コメントは設計ドキュメントの論理名を使用する
# 例
t.string :name, null: false, comment: "名前"
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.
- 6d ago First seen · 38 lines · 0 tokens per session scan A 87158e7f58a1
migration is a cursor rule published in the GitHub repository muraaano/cursor-project-rules-on-rails (2 stars, last pushed 1y ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 442 tokens. 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 2026-08-31.
Other cursor rules, from other repositories
prefer-assertions-over-defensive-checks
Prefer assertions over defensive checks when data is guaranteed to be valid.
as-contract-cast-smell
// ❌ WRONG — bypasses the family ContractSerializer seam const contract = JSON.parse(raw) as Contract; const contract = JSON.parse(raw) as Contract .
no-backward-compatibility
Do not add backward-compatibility shims or migration scaffolding.
postgresql
This guide defines the definitive best practices for writing clean, performant, and maintainable PostgreSQL SQL, focusing on modern conventions and avoiding common pitfalls.
query-optimization
查詢優化、EXPLAIN、index 設計與 RLS 效能測量.
ehs-ims-conventions
EHS IMS app — RBAC, data layer, tRPC, migrations, AI boundaries.