closest-worlds

closest-worlds is a skill for Claude Code, Codex from yogsoth-ai/de-anthropocentric-research-engine. It costs 33 tokens per session (791 once invoked), scanned A, original, Apache-2.0.

A counterfactual analysis method that finds the smallest change to the current situation that would reverse a conclusion. A counterfactual asks what would happen if a relevant condition were different.

In plain words
What is it for?
Use it to test causal arguments, find the point where they fail, and rank the factors supporting them.
Why use it?
It shows how fragile a conclusion is and which factors are closest to changing it.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions subagents.

Good fit Use it to test causal arguments, find the point where they fail, and rank the factors supporting them.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/yogsoth-ai/de-anthropocentric-research-engine/closest-worlds
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 yogsoth-ai/de-anthropocentric-research-engine --skill closest-worlds
Clone the repo
git clone --depth 1 https://github.com/yogsoth-ai/de-anthropocentric-research-engine

Made for: Claude Code, Codex.

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 closest-worlds

README.md
[![agentmods](https://agentmods.dev/badge/skills/yogsoth-ai/de-anthropocentric-research-engine/closest-worlds/github.svg)](https://agentmods.dev/skills/yogsoth-ai/de-anthropocentric-research-engine/closest-worlds)
Your own site
<a href="https://agentmods.dev/skills/yogsoth-ai/de-anthropocentric-research-engine/closest-worlds"><img src="https://agentmods.dev/badge/skills/yogsoth-ai/de-anthropocentric-research-engine/closest-worlds/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 closest-worlds

Your own site · 80×15
<a href="https://agentmods.dev/skills/yogsoth-ai/de-anthropocentric-research-engine/closest-worlds"><img src="https://agentmods.dev/badge/skills/yogsoth-ai/de-anthropocentric-research-engine/closest-worlds.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 33 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 791 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 warn 7 Sept 2026
SkillSpector: 1 finding, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high Prompt Injection · line 64
    Hidden instructions were detected in comments or invisible text. These could contain malicious directives. Manual review is recommended.
    Fix: Audit all comments and invisible characters. Remove any instructions that direct the agent to perform unauthorized actions. Use plain, reviewable content.
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 $0.00033 $0.00791
Opus 5 $0.00016 $0.00396
Sonnet 5 $0.00007 $0.00158
Haiku 4.5 $0.00003 $0.00079

Measured 7d ago against content hash 6b61fb85e1f9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

closest-worlds 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 7d 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

Copies of this mod

1 near-identical copy found in the catalogue:

skills/closest-worlds/SKILL.md · 89 lines

How it starts

The opening of the file, as written. The whole thing — 89 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Closest Worlds Strategy

Lewis semantics: evaluate counterfactuals by finding the nearest possible world where the antecedent holds and checking whether the consequent follows.

Method

  1. causal-claim-extraction identifies the conclusion and its supporting factors
  2. factor-enumeration maps the space of possible changes
  3. flip-point-detection searches for minimal changes that flip the conclusion
  4. counterfactual-scenario-construction builds the nearest world where conclusion fails
  5. fragility-measurement computes distance from actuality to flip-point
  6. load-bearing-identification ranks factors by proximity to flip

Budget Table

Parameter S M L
Change candidates explored 5 12 25
Flip-point searches 3 8 15
World-distance comparisons 3 6 12

Orchestration

causal-claim-extraction → factor-enumeration
→ [generate change candidates]:
    flip-point-detection (binary search for minimal flip)
    → counterfactual-scenario-construction (build nearest world)
    → fragility-measurement (compute distance)
→ load-bearing-identification (rank by proximity)

Subagents

  • causal-claim-extraction (conclusion identification)
  • factor-enumeration (change space mapping)
  • flip-point-detection (minimal flip search)
  • counterfactual-scenario-construction (world building)
  • fragility-measurement (distance computation)
  • load-bearing-identification (proximity ranking)

Available Tactics

Optional, no fixed order; the final leaf is always a sop.

Tactic When to use
minimal-change-search Tactic: Generate candidate changes, detect flip-points where conclusion reverses, measure fragility as distance to nearest flip.
systematic-factor-ablation Tactic: List all factors, remove one at a time, assess conclusion stability, rank factors by load-bearing importance.

Available SOPs

Optional, no fixed order; the final leaf is always a sop.

Read the full file on GitHub · 89 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. 7d ago First seen · 89 lines · 33 tokens per session scan A 6b61fb85e1f9

Subscribe to this mod's changes

closest-worlds is a skill published in the GitHub repository yogsoth-ai/de-anthropocentric-research-engine (456 stars, last pushed yesterday), licensed Apache-2.0. It adds 33 tokens to every session and 791 once invoked, about $0.0002 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.

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