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 caiaffa/claude-code-ultimate-engineering-system --skill database-engineeringgit clone --depth 1 https://github.com/caiaffa/claude-code-ultimate-engineering-systemWrote 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/caiaffa/claude-code-ultimate-engineering-system/database-engineering)<a href="https://agentmods.dev/skills/caiaffa/claude-code-ultimate-engineering-system/database-engineering"><img src="https://agentmods.dev/badge/skills/caiaffa/claude-code-ultimate-engineering-system/database-engineering/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/caiaffa/claude-code-ultimate-engineering-system/database-engineering"><img src="https://agentmods.dev/badge/skills/caiaffa/claude-code-ultimate-engineering-system/database-engineering.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00039 | $0.00430 |
| Opus 5.5 | $0.00016 | $0.00172 |
| Sonnet 5.5 | $0.00008 | $0.00086 |
| Haiku 4.5 | $0.00004 | $0.00043 |
Grade A, and why
database-engineering 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.
What it actually says
Mission
Produce data access that is correct, performant under real load, and safe to migrate without downtime.
When to use
- Writing or reviewing queries, schema, or migrations.
- Diagnosing slow queries or lock contention.
Handoff
- Receives from: backend-platform-engineer or architecture-decisions.
- Hands off to: backend-platform-engineer (implement), reliability-engineer (production impact).
Query & schema
- Every query that filters or joins must have a supporting index — verify with EXPLAIN.
- No N+1: batch or join instead of per-row queries.
- Select only needed columns; avoid SELECT *.
- Constraints (NOT NULL, FK, UNIQUE) belong in the schema, not just app code.
- Beware unbounded result sets — paginate.
Migration safety (zero-downtime)
- Adding a column: nullable or with a default that doesn't rewrite the table.
- Adding an index: CREATE INDEX CONCURRENTLY.
- Dropping/renaming: multi-step — deploy code that tolerates both states first.
- Backfills: batched, throttled, resumable — never one giant UPDATE.
- Every migration must have a tested rollback or be explicitly marked irreversible.
Performance & safety
- Long transactions hold locks — keep them short.
- Know the lock level of each DDL statement.
- Connection pool sized to the database, not the app instance count.
- Statement timeout set so a runaway query can't pin the DB.
Red flags
- Migration that rewrites a large table in one statement.
- Query with no index and no row-count bound.
CREATE INDEXwithoutCONCURRENTLYon a live table.
Output
Notes covering: index plan (with EXPLAIN evidence), migration steps + rollback, lock impact, expected behavior at production row counts.
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 First seen · 45 lines · 39 tokens per session scan A dfdfc9360fe5
database-engineering is a skill published in the GitHub repository caiaffa/claude-code-ultimate-engineering-system (17 stars, last pushed 1mo ago), licensed MIT. It adds 39 tokens to every session and 430 once invoked, about $0.0002 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 2026-09-15.
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