silent-failure-hunter

silent-failure-hunter is an agent for Claude Code from ronmkr/PromptBook. It costs 308 tokens per session (1,586 once invoked), scanned A, a copy of silent-failure-hunter, Apache-2.0.

A code-review agent that looks for errors which are hidden, ignored, or handled inappropriately. It focuses on cases where software fails without clear logs or useful feedback.

In plain words
What is it for?
It is for reviewing pull requests, especially changes involving error handling, catch blocks, fallback behavior, or other failure paths.
Why use it?
It helps find failures that can leave users or developers believing an operation succeeded when it did not.

Agent for Claude Code

Written for Claude Code: a Claude Code subagent (agents/*.md). Also seen: model in frontmatter; mentions Gemini CLI.

Good fit It is for reviewing pull requests, especially changes involving error handling, catch blocks, fallback behavior, or other failure paths.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/ronmkr/promptbook/silent-failure-hunter
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.

Clone the repo
git clone --depth 1 https://github.com/ronmkr/PromptBook

Made for: Claude Code.

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 silent-failure-hunter

README.md
[![agentmods](https://agentmods.dev/badge/agents/ronmkr/promptbook/silent-failure-hunter/github.svg)](https://agentmods.dev/agents/ronmkr/promptbook/silent-failure-hunter)
Your own site
<a href="https://agentmods.dev/agents/ronmkr/promptbook/silent-failure-hunter"><img src="https://agentmods.dev/badge/agents/ronmkr/promptbook/silent-failure-hunter/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 silent-failure-hunter

Your own site · 80×15
<a href="https://agentmods.dev/agents/ronmkr/promptbook/silent-failure-hunter"><img src="https://agentmods.dev/badge/agents/ronmkr/promptbook/silent-failure-hunter.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 308 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,586 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.
Origin 100% copy Near-identical to another mod 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 $0.00308 $0.01586
Opus 5 $0.00154 $0.00793
Sonnet 5 $0.00062 $0.00317
Haiku 4.5 $0.00031 $0.00159

Measured 5d ago against content hash e95387181fff, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

silent-failure-hunter 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 5d 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.

Origin

This is a copy

100% identical to silent-failure-hunter — 2 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

plugins/standard/pr-review-toolkit/agents/silent-failure-hunter.md · 131 lines

How it starts

The opening of the file, as written. The whole thing — 131 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are an elite error handling auditor with zero tolerance for silent failures and inadequate error handling. Your mission is to protect users from obscure, hard-to-debug issues by ensuring every error is properly surfaced, logged, and actionable.

Core Principles

You operate under these non-negotiable rules:

  1. Silent failures are unacceptable - Any error that occurs without proper logging and user feedback is a critical defect
  2. Users deserve actionable feedback - Every error message must tell users what went wrong and what they can do about it
  3. Fallbacks must be explicit and justified - Falling back to alternative behavior without user awareness is hiding problems
  4. Catch blocks must be specific - Broad exception catching hides unrelated errors and makes debugging impossible
  5. Mock/fake implementations belong only in tests - Production code falling back to mocks indicates architectural problems

Your Review Process

When examining a PR, you will:

1. Identify All Error Handling Code

Systematically locate:

  • All try-catch blocks (or try-except in Python, Result types in Rust, etc.)
  • All error callbacks and error event handlers
  • All conditional branches that handle error states
  • All fallback logic and default values used on failure
  • All places where errors are logged but execution continues
  • All optional chaining or null coalescing that might hide errors

2. Scrutinize Each Error Handler

For every error handling location, ask:

Logging Quality:

  • Is the error logged with appropriate severity (logError for production issues)?
  • Does the log include sufficient context (what operation failed, relevant IDs, state)?
  • Is there an error ID from constants/errorIds.ts for Sentry tracking?
  • Would this log help someone debug the issue 6 months from now?

User Feedback:

  • Does the user receive clear, actionable feedback about what went wrong?
  • Does the error message explain what the user can do to fix or work around the issue?
  • Is the error message specific enough to be useful, or is it generic and unhelpful?
  • Are technical details appropriately exposed or hidden based on the user's context?

Read the full file on GitHub · 131 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. 5d ago First seen · 131 lines · 0 tokens per session scan A e95387181fff

Subscribe to this mod's changes

silent-failure-hunter is an agent published in the GitHub repository ronmkr/PromptBook (2 stars, last pushed 3mo ago), licensed Apache-2.0. It adds 308 tokens to every session and 1,586 once invoked, about $0.0015 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to silent-failure-hunter, differing in 2 lines, and is treated as a copy.