skill-sync-checker

skill-sync-checker is a skill for Claude Code, Codex from kanyun-inc/reskill. It costs 35 tokens per session (1,999 once invoked), scanned A, original, MIT.

A maintenance utility for checking skill files against the documents they come from. It uses source markers in the skill file to find sections that may be out of date.

In plain words
What is it for?
Checking whether a skill is current, finding outdated sections, and reviewing skills after editing their source documents.
Why use it?
It helps prevent reusable instructions from becoming inaccurate after their source documentation changes. It also highlights skills that may need review before publishing.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Checking whether a skill is current, finding outdated sections, and reviewing skills after editing their source documents.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/kanyun-inc/reskill/skill-sync-checker
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 kanyun-inc/reskill --skill skill-sync-checker
Clone the repo
git clone --depth 1 https://github.com/kanyun-inc/reskill

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 skill-sync-checker

README.md
[![agentmods](https://agentmods.dev/badge/skills/kanyun-inc/reskill/skill-sync-checker.svg)](https://agentmods.dev/skills/kanyun-inc/reskill/skill-sync-checker)
Your own site
<a href="https://agentmods.dev/skills/kanyun-inc/reskill/skill-sync-checker"><img src="https://agentmods.dev/badge/skills/kanyun-inc/reskill/skill-sync-checker.svg" alt="Measured on agentmods" height="20"></a>
Per session 35 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,999 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: 12 findings, 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 17
    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.
  • high Rogue Agent · line 166
    Skill modifies its own code, configuration, or behavior at runtime. Self-modification enables an agent to escalate privileges, disable safety constraints, or install persistent backdoors.
    Fix: Prevent the skill from modifying its own code, SKILL.md, or configuration files. Treat skill files as read-only at runtime.
  • high Rogue Agent · line 204
    Skill modifies its own code, configuration, or behavior at runtime. Self-modification enables an agent to escalate privileges, disable safety constraints, or install persistent backdoors.
    Fix: Prevent the skill from modifying its own code, SKILL.md, or configuration files. Treat skill files as read-only at runtime.
  • medium Excessive Agency · line 39
    Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.
    Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
  • medium Agent Snooping · line 44
    Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.
    Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
  • medium Agent Snooping · line 121
    Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.
    Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
  • medium Agent Snooping · line 138
    Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.
    Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
  • medium Agent Snooping · line 214
    Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.
    Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
  • medium Agent Snooping · line 246
    Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.
    Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
  • medium Agent Snooping · line 150
    Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.
    Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
  • medium Agent Snooping · line 245
    Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.
    Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
  • medium Agent Snooping · line 247
    Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.
    Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
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 $0.00035 $0.01999
Opus 5 $0.00017 $0.01000
Sonnet 5 $0.00007 $0.00400
Haiku 4.5 $0.00003 $0.00200

Measured 8d ago against content hash 9c126666b723, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

skill-sync-checker 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.

skills/skill-sync-checker/SKILL.md · 256 lines

How it starts

The opening of the file, as written. The whole thing — 256 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill Sync Checker

A utility skill that detects when skill content has drifted from its source documents. Any skill file that includes a <!-- source: path/to/file --> marker can be checked for freshness and updated accordingly.

When to Use This Skill

User-Initiated (Agent Requested)

Use this skill when the user:

  • Asks to check if a skill's content is up to date
  • Has modified source documentation and wants to sync derived skills
  • Is preparing a skill for publishing and wants to verify freshness
  • Asks "is this skill still accurate?" or "has the source changed?"
  • Performs routine maintenance on skills

Auto-Triggered (via Cursor globs)

This skill is automatically injected into context when the user edits README.md (configurable via .cursor/rules/skill-sync-checker.mdc globs).

When auto-triggered, follow this lightweight flow:

  1. Scan skills/**/SKILL.md for <!-- source: ... --> markers referencing the file being edited
  2. If a match is found, briefly remind the user that a skill depends on this file and may need syncing
  3. Do not automatically run the full detection workflow or modify any files — just notify

Example notification:

Note: skills/reskill-usage/SKILL.md is derived from README.md (last synced: 2026-02-12).
If your changes affect CLI commands, options, or usage examples, the skill may need updating.
Run a sync check when you're done editing.

Source Marker Convention

Skill files that are derived from other documents should include source markers as HTML comments at the top of the file (before or after the YAML frontmatter):

<!-- source: README.md -->
<!-- synced: 2026-02-11 -->

---
name: my-skill
description: ...
---

# My Skill
...

Marker Format

Marker Required Description
<!-- source: <path> --> Yes Relative path to the source file (from project root)
<!-- synced: <date> --> No ISO date of last sync (YYYY-MM-DD)

Read the full file on GitHub · 256 lines

Files

What ships with it

1 file 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. 8d ago First seen · 256 lines · 35 tokens per session scan A 9c126666b723

Subscribe to this mod's changes

skill-sync-checker is a skill published in the GitHub repository kanyun-inc/reskill (59 stars, last pushed 27d ago), licensed MIT. It adds 35 tokens to every session and 1,999 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 2026-08-30.

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