bug-hunt

bug-hunt is a skill for Claude Code from escoffier-labs/skillet. It costs 45 tokens per session (910 once invoked), scanned A, a copy of bug-hunt, MIT.

A read-only process for finding and verifying correctness bugs in a codebase.

In plain words
What is it for?
Use it to inspect logic, error handling, edge cases, concurrency, and API usage for reachable, important defects without changing the code.
Why use it?
It filters out plausible but incorrect reports by requiring each suspected defect to survive attempts to disprove it.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: mentions subagents.

Part of the skillet plugin — 39 skills, 1 hook shipped together

Good fit Use it to inspect logic, error handling, edge cases, concurrency, and API usage for reachable, important defects without changing the code.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/escoffier-labs/skillet/bug-hunt
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.

Any agent
npx skills add escoffier-labs/skillet --skill bug-hunt
Clone the repo
git clone --depth 1 https://github.com/escoffier-labs/skillet

Made for: Claude Code.

Or install skillet, the plugin that ships this one along with the rest of its 39 skills, 1 hook.

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 bug-hunt

README.md
[![agentmods](https://agentmods.dev/badge/skills/escoffier-labs/skillet/bug-hunt/github.svg)](https://agentmods.dev/skills/escoffier-labs/skillet/bug-hunt)
Your own site
<a href="https://agentmods.dev/skills/escoffier-labs/skillet/bug-hunt"><img src="https://agentmods.dev/badge/skills/escoffier-labs/skillet/bug-hunt/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 bug-hunt

Your own site · 80×15
<a href="https://agentmods.dev/skills/escoffier-labs/skillet/bug-hunt"><img src="https://agentmods.dev/badge/skills/escoffier-labs/skillet/bug-hunt.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 45 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 910 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 94% 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 $0.00045 $0.00910
Opus 5 $0.00023 $0.00455
Sonnet 5 $0.00009 $0.00182
Haiku 4.5 $0.00005 $0.00091

Measured 10d ago against content hash bfa8778465ca, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

bug-hunt 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 10d 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

94% identical to bug-hunt — 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.

skillet/skills/bug-hunt/SKILL.md · 77 lines

How it starts

The opening of the file, as written. The whole thing — 77 lines — stays where its author put it; the contents beside it link to each section on GitHub.

bug-hunt

A correctness sweep that only reports bugs it failed to refute. Finders generate candidates; verifiers try to kill them; survivors make the report. The single biggest failure mode of agent bug-hunting is plausible-but-wrong findings, so verification is not optional.

Read-only. Finding bugs and fixing them are separate engagements.

Lenses

Sweep with each lens. With parallel subagents available, one finder per lens; otherwise sequential passes.

Lens Hunting for
Logic Inverted conditions, off-by-one, wrong operator, unreachable branches, broken invariants
Error handling Swallowed exceptions, missing error paths, errors that corrupt state before propagating, misleading messages
Edge cases Empty/nil/zero inputs, unicode, huge inputs, boundary values, first/last iteration
Concurrency Races, missing locks, shared mutable state, TOCTOU, async ordering assumptions
API misuse Contract violations against libraries and the project's own interfaces, ignored return values, resource leaks, lifecycle errors

Focus finders on code that is reachable and load-bearing: entry points, hot paths, recently changed files (git log --since is a good prior). A bug in dead code is info, not a finding.

Two deep lenses live as their own skills: latent-premises for unguarded assumptions that hold today with no trigger yet, and retry-safety for side effects that double-apply on a re-run. Reach for them when the sweep keeps surfacing "could break later" candidates that fail the trigger rule.

Verification (mandatory)

Every candidate gets an adversarial pass before it may appear in the report. The verifier's job is to REFUTE the finding, default skeptical:

  1. Read the actual code path end to end, including callers and guards the finder may have missed.
  2. Trace a concrete input that triggers the bug. No trigger, no bug.
  3. Check whether a test, type system, or runtime check already prevents it.
  4. Verdict: confirmed (with the triggering scenario), refuted (drop silently), or unverifiable (report downgraded one severity, marked (unverified)).

Read the full file on GitHub · 77 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 10d ago First seen · 77 lines · 45 tokens per session scan A bfa8778465ca

Subscribe to this mod's changes

bug-hunt is a skill published in the GitHub repository escoffier-labs/skillet (4 stars, last pushed 9d ago), licensed MIT. It adds 45 tokens to every session and 910 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 94% identical to bug-hunt, differing in 2 lines, and is treated as a copy.

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