mandela

mandela is a skill for Claude Code, Codex from LilMGenius/paperthin. It costs 106 tokens per session (711 once invoked), scanned A, original, MIT.

A review method for checking whether an evaluation, metric, experiment, or benchmark uses independent outside truth. It looks for situations where the model, scorer, or test designer may be confirming an answer without an independent reference.

In plain words
What is it for?
Use it to audit A/B tests, holdouts, scores, validations, and other claims about whether a system worked.
Why use it?
It helps reveal when a reported result may be misleading because the validation process is leaking the expected answer.

Skill for Claude CodeCodex

Part of the paperthin plugin — 28 skills shipped together

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 skills/lilmgenius/paperthin/mandela
Any agent
npx skills add LilMGenius/paperthin --skill mandela
Clone the repo
git clone --depth 1 https://github.com/LilMGenius/paperthin

Made for: Claude Code, Codex.

Or install paperthin, the plugin that ships this one along with the rest of its 28 skills.

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 mandela

README.md
[![agentmods](https://agentmods.dev/badge/skills/lilmgenius/paperthin/mandela.svg)](https://agentmods.dev/skills/lilmgenius/paperthin/mandela)
Your own site
<a href="https://agentmods.dev/skills/lilmgenius/paperthin/mandela"><img src="https://agentmods.dev/badge/skills/lilmgenius/paperthin/mandela.svg" alt="Measured on agentmods" height="20"></a>
Per session 106 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 711 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 $0.00106 $0.00711
Opus 5 $0.00053 $0.00356
Sonnet 5 $0.00021 $0.00142
Haiku 4.5 $0.00011 $0.00071

Measured 5d ago against content hash 5efc42ffa98a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

mandela 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.

skills/depth/mandela/SKILL.md · 43 lines

How it starts

The opening of the file, as written. The whole thing — 43 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Audit a validation for leakage: does outside ground-truth actually enter, or is everyone confirming a result no one independently produced?

Goal

The name is the Mandela Effect — a whole population confidently remembers something that never independently happened; a leaky validation is the same shape. Walk the 8 patterns below. mandela checks one thing: whether a validation is independent, or whether the designer, model, and scorer are only confirming each other.

Workflow

  1. Identify the validation (eval / metric / experiment / holdout / "how we'll know"). Name its components — what plays model, scorer, designer, dataset.
  2. Ask the core question: does external ground-truth enter independently?
  3. Test the validation against all 8 patterns below (some apply only to certain components — a human subject, a scorer); report only the ones that fire, each by name.
  4. Give the independent-ground-truth fix for each hit.

The 8 leakage patterns

  1. Recall, not reason — a memorized answer recited instead of one actually derived; the system already knows the result it is supposedly computing.
  2. Wrong null hypothesis — an ablation that removes a surface label but not the underlying signal the system actually exploits, so the "control" still leaks.
  3. Shared hallucination — two components verifying each other; circularity reported as a number.
  4. Tautology — a scorer grading buckets it drew itself.
  5. Verifier = designer — a private, unreproducible recipe in a holdout's clothes.
  6. Shared-pool bias — train and holdout drawn from one labeler pool, so one bias enters both sides.
  7. Frame injection — a question that hands the subject the hypothesis.
  8. Demand characteristics — measured subjects who know they're being measured.

Rules

  • Subtlety that bites twice: you can blind the output value and still leak the collection recipe.
  • Read-only — name the leak and the independence fix; don't rewrite the experiment.
  • For a high-stakes validation, you may add one independent fresh-context auditor (N=1) handed only the validation design, not this session's reasoning, to re-run the 8-pattern taxonomy blind; the default remains same-session and read-only.

Read the full file on GitHub · 43 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 · 43 lines · 106 tokens per session scan A 5efc42ffa98a

Subscribe to this mod's changes

mandela is a skill published in the GitHub repository LilMGenius/paperthin (1,054 stars, last pushed 17d ago), licensed MIT. It adds 106 tokens to every session and 711 once invoked, about $0.0005 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.

Related

Other skills, from other repositories

research-extraction

Deep extraction of research corpora into structured knowledge documents using a Workflow-driven subagent/reviewer pattern. Use when you have raw source documents (theses, papers, reports) and need structured extraction across multiple axes (architecture, messages, algorithms, forms, etc.) with confidence-annotated…

geronimo-iia/agent-skills · 87 tokens

scientific-critical-thinking

Evaluate scientific claims and evidence quality. Use for assessing experimental design validity, identifying biases and confounders, applying evidence grading frameworks (GRADE, Cochrane Risk of Bias), or teaching critical analysis. Best for understanding evidence quality, identifying flaws. For formal peer review…

K-Dense-AI/claude-scientific-writer · 63 tokens

paper-planning

Guides pre-writing planning for academic papers with 4 structured steps: story design (task-challenge-insight-contribution-advantage), experiment planning (comparisons + ablations), figure design (pipeline + teaser), and 4-week timeline management. Includes counterintuitive planning tactics (write a mock rejection…

EvoScientist/EvoSkills · 166 tokens

evo-memory

Manages persistent research memory across ideation and experimentation cycles. Maintains two stores: Ideation Memory MI (feasible/unsuccessful directions) and Experimentation Memory ME (reusable strategies for data processing, model training, architecture, debugging). Three evolution mechanisms: IDE (after…

EvoScientist/EvoSkills · 186 tokens

paper2poster

Convert academic papers (PDF) into conference posters (HTML/PNG). You are the conductor: you decide what each section needs — an original paper figure or text — write the outline, hand-author the poster HTML, and iterate on the render using your own visual read and a blind-reader content quiz. Use when the user wants…

QuZhan51496/paper2anything · 76 tokens

iterate-from-user

Source the next ML experiment proposal from the user via one of three entry points selected by AskUserQuestion: (a) a scientific article URL the agent must read and synthesize, (b) a resource link or path (GitHub issue / spec file / reference repo), or (c) free-text the user types directly. In every branch, the agent…

probabl-ai/skills · 401 tokens