db

A guide for changing a database’s structure, such as adding or modifying tables or fields, using migrations, which are recorded steps that update the database.

In plain words
What is it for?
Use it when creating, applying, testing, or rolling back database schema changes and updating related test data.
Why use it?
It helps preserve migration history, avoid unsafe changes, and verify that existing data remains correct.

Skill for Claude CodeCodexCursor

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/marcecandil/agent-context-kit/db
Any agent
npx skills add MarceCandil/agent-context-kit --skill db
Clone the repo
git clone --depth 1 https://github.com/MarceCandil/agent-context-kit

Made for: Claude Code, Codex, Cursor.

Per session 20 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 151 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 $0.00020 $0.00151
Opus 5 $0.00010 $0.00076
Sonnet 5 $0.00004 $0.00030
Haiku 4.5 $0.00002 $0.00015

Measured 2d ago against content hash 10e0af8ab175, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

db 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 2d 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.

.cursor/skills/db/SKILL.md · 24 lines

What it actually says

Skill: Database & migrations

Rules

  • Never edit migration history retroactively once merged.
  • Prefer additive changes (new migrations) over rewriting.

Procedure

  1. Describe the schema change in plain language.
  2. Generate a migration using the repo’s standard command.
  3. Apply migration locally.
  4. Update seeds/fixtures (if required).
  5. Add minimal tests (or verification steps) to prove data integrity.

Safety

  • Avoid destructive operations without explicit confirmation.
  • For risky changes, propose a rollback plan.
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. 2d ago First seen · 24 lines · 20 tokens per session scan A 10e0af8ab175

Subscribe to this mod's changes

db is a skill published in the GitHub repository MarceCandil/agent-context-kit (2 stars, last pushed 6mo ago), licensed MIT. It adds 20 tokens to every session and 151 once invoked, about $0.0001 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 2026-08-31.

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