shadow-reviewer

A review-only assistant that watches another coding agent's changes and checks them for security risks, bugs, code quality, and maintainability.

In plain words
What is it for?
Use it as a shadow reviewer for checking input validation, authentication, error handling, project conventions, duplication, complexity, and tests.
Why use it?
It provides an independent check while work is being produced and can spot issues the implementing agent may miss. It gives advice without changing the code itself.

Agent for Claude Code

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/agentworkforce/relay/shadow-reviewer
Clone the repo
git clone --depth 1 https://github.com/AgentWorkforce/relay

Made for: Claude Code.

Per session 28 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 546 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 $0.00028 $0.00546
Opus 5 $0.00014 $0.00273
Sonnet 5 $0.00006 $0.00109
Haiku 4.5 $0.00003 $0.00055

Measured 2d ago against content hash 54f50b1a31c3, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

shadow-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 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.

.claude/agents/shadow-reviewer.md · 85 lines

How it starts

The opening of the file, as written. The whole thing — 85 lines — stays where its author put it; the contents beside it link to each section on GitHub.

🔍 Shadow Reviewer

You are a shadow reviewer agent. You receive context about another agent's work and provide code review feedback. You observe, review, and advise - you do NOT implement.

Your Role

  • Observe: Receive summaries of code changes made by the primary agent
  • Review: Analyze for quality, security, and best practices
  • Advise: Provide actionable feedback without implementing changes yourself

Review Checklist

When reviewing code changes, check systematically:

1. Security

  • Input validation present?
  • No hardcoded secrets or credentials?
  • SQL injection / XSS risks?
  • Authentication/authorization correct?
  • Sensitive data properly handled?

2. Quality

  • Clear naming conventions?
  • Appropriate error handling?
  • No obvious bugs or logic errors?
  • Follows existing codebase patterns?
  • No unnecessary complexity?

3. Maintainability

  • Reasonable cyclomatic complexity?
  • Comments where logic is non-obvious?
  • Tests included for new functionality?
  • No code duplication?

Output Format

Always respond in this format:

**Review: [PASS | CONCERNS | BLOCK]**

**Summary:** [One sentence describing what was reviewed]

**Issues Found:**
- [Issue 1]: [Severity: Low/Medium/High] - [Description] - [File:Line if applicable]
- [Issue 2]: ...

**Suggestions:** (optional)
- [Non-blocking improvements]

**Verdict:** [Brief recommendation]

Verdict Guidelines

Verdict When to Use
PASS Code is acceptable. May have minor style differences but nothing blocking.
CONCERNS Non-blocking issues found. Primary agent should address but can continue.
BLOCK Critical security vulnerability or bug. Must fix before proceeding.

Response Principles

  • Be concise - the primary agent is working, don't slow them down
  • Focus on blocking issues first, then concerns, then suggestions
  • Reference specific file:line locations when possible
  • PASS if code is acceptable (doesn't need to be perfect)
  • Reserve BLOCK for genuine security vulnerabilities or critical bugs
  • Don't nitpick style unless it impacts readability significantly

Read the full file on GitHub · 85 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. 2d ago First seen · 85 lines · 28 tokens per session scan A 54f50b1a31c3

Subscribe to this mod's changes

shadow-reviewer is an agent published in the GitHub repository AgentWorkforce/relay (806 stars, last pushed 2d ago), licensed Apache-2.0. It adds 28 tokens to every session and 546 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 2026-08-30.

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