challenge

challenge is a skill for Claude Code from athola/claude-night-market. It costs 26 tokens per session (571 once invoked), scanned A, original, MIT.

A codebase learning tool that asks adaptive multiple-choice and code-tracing questions about a project's existing code and records the developer's progress.

In plain words
What is it for?
It helps test contributor knowledge, explain how code behaves, and track results across repeated challenges.
Why use it?
It gives contributors a way to check whether they understand unfamiliar code before making changes.

Skill for Claude Code

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

Part of the gauntlet plugin — 7 skills, 6 commands, 1 agent shipped together

Good fit It helps test contributor knowledge, explain how code behaves, and track results across repeated challenges.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/athola/claude-night-market/challenge
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 athola/claude-night-market --skill challenge
Clone the repo
git clone --depth 1 https://github.com/athola/claude-night-market

Made for: Claude Code.

Or install gauntlet, the plugin that ships this one along with the rest of its 7 skills, 6 commands, 1 agent.

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 challenge

README.md
[![agentmods](https://agentmods.dev/badge/skills/athola/claude-night-market/challenge/github.svg)](https://agentmods.dev/skills/athola/claude-night-market/challenge)
Your own site
<a href="https://agentmods.dev/skills/athola/claude-night-market/challenge"><img src="https://agentmods.dev/badge/skills/athola/claude-night-market/challenge/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 challenge

Your own site · 80×15
<a href="https://agentmods.dev/skills/athola/claude-night-market/challenge"><img src="https://agentmods.dev/badge/skills/athola/claude-night-market/challenge.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 26 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 571 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 5.1 $0.00026 $0.00571
Opus 5 $0.00013 $0.00285
Sonnet 5 $0.00005 $0.00114
Haiku 4.5 $0.00003 $0.00057

Measured 8d ago against content hash 408425855e02, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

challenge 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 8d 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.

plugins/gauntlet/skills/challenge/SKILL.md · 75 lines

How it starts

The opening of the file, as written. The whole thing — 75 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Run Gauntlet Challenge

Present challenges from the knowledge base and evaluate answers.

When NOT To Use

  • The knowledge base does not exist yet (use gauntlet:extract)
  • A staged path for a new contributor (use gauntlet:onboard)

In-Loop Provider Setup

Before generating a challenge, register the in-loop variation provider so we do not call out to the Anthropic API just to spawn a sibling Claude (issue #464). Outside Claude Code this is a no-op and the default Anthropic provider remains active.

from gauntlet.providers.in_loop import (
    register_in_loop_provider_if_inside_claude_code,
)
register_in_loop_provider_if_inside_claude_code()

Steps

  1. Load state: read .gauntlet/knowledge.json and developer progress

  2. Check for pending challenge: if .gauntlet/state/pending_challenge.json exists, evaluate the developer's most recent message as an answer before generating a new one

  3. Generate challenge: use adaptive weighting to select a knowledge entry and challenge type

  4. Present challenge: show the question with context

  5. Evaluate answer: score the response (pass/partial/fail)

  6. Record result: update developer progress and streak

  7. On pass: write pass token if from pre-commit gate. Show next challenge if in session.

  8. On fail: show correct answer with explanation. Present a new challenge.

Scoring

Result Score Streak
Pass 1.0 +1
Partial 0.5 reset
Fail 0.0 reset

Exit Criteria

  • .gauntlet/knowledge.json exists and is readable before a challenge is generated; if missing, the skill surfaces the error and suggests running gauntlet:extract
  • Each challenge attempt results in a score (1.0/0.5/0.0) written to the developer's progress store and a streak update applied
  • .gauntlet/state/pending_challenge.json is evaluated before generating a new challenge when it exists; the file is removed or updated after evaluation
  • On fail, the correct answer and explanation are shown before the next challenge is presented (not skipped silently)

Read the full file on GitHub · 75 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. 8d ago First seen · 75 lines · 26 tokens per session scan A 408425855e02

Subscribe to this mod's changes

challenge is a skill published in the GitHub repository athola/claude-night-market (337 stars, last pushed yesterday), licensed MIT. It adds 26 tokens to every session and 571 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 2026-09-03.