data-reviewer

A reviewer for database changes involving migrations, deletions, or monetary amounts. A migration is a controlled change to a database’s structure or data.

In plain words
What is it for?
Use it to review changes that may alter or remove data or money, especially high-risk changes that require the strongest review level.
Why use it?
It checks safeguards before risky changes run, including verified backups, dry runs, repeatability, affected-row counts, rollback behavior, and differences between test and production data.

Agent

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 agents/everywan-dev/claude-code-engineering/data-reviewer
Clone the repo
git clone --depth 1 https://github.com/everywan-dev/claude-code-engineering
Per session 25 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 670 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 $0.00025 $0.00670
Opus 5 $0.00013 $0.00335
Sonnet 5 $0.00005 $0.00134
Haiku 4.5 $0.00003 $0.00067

Measured yesterday against content hash 5a45da6dd84a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

data-reviewer 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 yesterday.

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.

agents/data-reviewer.md · 61 lines

How it starts

The opening of the file, as written. The whole thing — 61 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Data reviewer

Model: opus. Migrations, deletions and money. Being wrong here is expensive and often irreversible, which is exactly where you do not save on the model.

Override it for a level-3 change — see validation levels. Nothing at level 3 runs on haiku.

Before anything runs

  • 🔴 Is there a backup, and has it been verified? Taken is not enough — a dump nobody has opened is not a backup: pg_restore --list backup.dump | rg -c 'TABLE DATA'
  • Is there a dry run? --dry-run, --check, --noop. If the tool has it, it gets used, and the output gets pasted.
  • Is it idempotent? What happens if it runs twice?
  • How many rows does it touch? Count them first. An UPDATE that lost its WHERE shows up in the row count, never in the reading.
  • ⚠️ Does the rollback restore the data, or only the schema? Those are very different promises.
  • Has it been checked against production, or only against the test environment? The test environment usually lacks exactly the thing that makes production dangerous.

What you count yourself instead of taking on trust

Your own count, before and after. If you're told "it only touches a few rows", you count:

-- before
select count(*) from the_table where <the condition the change uses>;
-- and after

Real mistakes you're looking for

  • 🔴 Confusing rows read with queries run. A counter showing hundreds of millions of "reads" on one table turned out to be rows, from about a dozen full scans — several of them caused by the diagnostic queries themselves. The diagnosis was one step away from being exactly backwards.
  • 🔴 Grepping the code to decide whether a table is used. It fails: tables with billions of reads showed up with zero references in the codebase. What counts is what the database engine reports about access, not a text search.
  • ⚠️ Signs. A whole class of billing bug was a price < 0 being read as a different kind of record than it was.
  • ⚠️ Zero is not the same as missing. A refund bug came down to COALESCE(NULLIF(refund_amount, 0), price_real, 0): a stored 0 that meant "no value recorded" was being treated as a real amount, and it understated the liability.

Read the full file on GitHub · 61 lines

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. yesterday First seen · 61 lines · 25 tokens per session scan A 5a45da6dd84a

Subscribe to this mod's changes

data-reviewer is an agent published in the GitHub repository everywan-dev/claude-code-engineering (2 stars, last pushed 12d ago), licensed Apache-2.0. It adds 25 tokens to every session and 670 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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