database-migrations

database-migrations is a skill for Claude Code, Codex from HoangNguyen0403/agent-skills-standard. It costs 40 tokens per session (312 once invoked), scanned A, original, MIT.

A plan for changing a database structure safely while an application remains online. It covers adding the new shape, moving existing data, switching application code, and removing the old shape later.

In plain words
What is it for?
Use it to plan schema changes, data backfills, rollout order, monitoring, and rollback steps for production databases.
Why use it?
It reduces outages and makes risky changes such as renaming columns or backfilling data easier to pause, monitor, and roll back.

Skill for Claude CodeCodex

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

Good fit Use it to plan schema changes, data backfills, rollout order, monitoring, and rollback steps for production databases.

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Install with agentmods
npx agentmods add skills/hoangnguyen0403/agent-skills-standard/database-migrations
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 HoangNguyen0403/agent-skills-standard --skill database-migrations
Clone the repo
git clone --depth 1 https://github.com/HoangNguyen0403/agent-skills-standard

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 database-migrations

README.md
[![agentmods](https://agentmods.dev/badge/skills/hoangnguyen0403/agent-skills-standard/database-migrations/github.svg)](https://agentmods.dev/skills/hoangnguyen0403/agent-skills-standard/database-migrations)
Your own site
<a href="https://agentmods.dev/skills/hoangnguyen0403/agent-skills-standard/database-migrations"><img src="https://agentmods.dev/badge/skills/hoangnguyen0403/agent-skills-standard/database-migrations/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.

agentmods 80×15 button for database-migrations

Your own site · 80×15
<a href="https://agentmods.dev/skills/hoangnguyen0403/agent-skills-standard/database-migrations"><img src="https://agentmods.dev/badge/skills/hoangnguyen0403/agent-skills-standard/database-migrations.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 40 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 312 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00040 $0.00312
Opus 5 $0.00020 $0.00156
Sonnet 5 $0.00008 $0.00062
Haiku 4.5 $0.00004 $0.00031

Measured 9d ago against content hash d9737eb1f7ef, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

database-migrations 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 9d 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/database/database-migrations/SKILL.md · 47 lines

What it actually says

Database Migrations

Priority: P0 (CRITICAL)

Use expand -> backfill -> contract for risky changes.

Rules

  • Ship additive schema first.
  • Backfill with resumable logic and visibility.
  • Flip reads/writes only after new shape is populated.
  • Drop old columns or indexes in a later safe step.

Verify

  • Migration can run without taking the app offline.
  • Backfill ownership, batching, and monitoring are defined.
  • Rollback or pause strategy exists.
  • Old and new code paths can coexist during rollout.

Anti-Patterns

  • No destructive one-shot rename: expand and migrate first.
  • No hidden backfill: long data moves need explicit plan and observability.
  • No app deploy coupling by accident: schema and code rollout order must be clear.

References

Files

What ships with it

2 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.

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. 9d ago First seen · 47 lines · 40 tokens per session scan A d9737eb1f7ef

Subscribe to this mod's changes

database-migrations is a skill published in the GitHub repository HoangNguyen0403/agent-skills-standard (565 stars, last pushed 3d ago), licensed MIT. It adds 40 tokens to every session and 312 once invoked, about $0.0002 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.