regex

regex is a skill for Claude Code, Codex from dhaupin/vant. It costs 5 tokens per session (276 once invoked), scanned A, original, MIT.

A guide to regular expressions, patterns used to find, validate, or extract text. It explains symbols for repetitions, character groups, captured sections, and common matching operations.

In plain words
What is it for?
Use it to find numbers or other repeated text, validate inputs such as email addresses, and extract matching parts from strings.
Why use it?
It helps describe text patterns precisely instead of checking every possible string manually.

Skill for Claude CodeCodex

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

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/dhaupin/vant/vant-skill-regex
Any agent
npx skills add dhaupin/vant --skill vant-skill-regex
Clone the repo
git clone --depth 1 https://github.com/dhaupin/vant

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 regex

README.md
[![agentmods](https://agentmods.dev/badge/skills/dhaupin/vant/vant-skill-regex.svg)](https://agentmods.dev/skills/dhaupin/vant/vant-skill-regex)
Your own site
<a href="https://agentmods.dev/skills/dhaupin/vant/vant-skill-regex"><img src="https://agentmods.dev/badge/skills/dhaupin/vant/vant-skill-regex.svg" alt="Measured on agentmods" height="20"></a>
Per session 5 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 276 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 5.1 $0.00005 $0.00276
Opus 5 $0.00003 $0.00138
Sonnet 5 $0.00001 $0.00055
Haiku 4.5 $0.00001 $0.00028

Measured 6d ago against content hash 522991630b84, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

regex 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 6d 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.

models/public/skills/vant-skill-regex/SKILL.md · 69 lines

What it actually says

Regex

Pattern matching.


When To Use

  • Find patterns
  • Validate input
  • Extract data

What To Do

1. Basics

Pattern What
. Any character
* 0 or more
+ 1 or more
? 0 or 1
^ Start
$ End

2. Classes

[abc]       # a, b, or c
[^abc]      # not a, b, c
[a-z]       # a to z
\d          # digit
\w          # word
\s          # space

3. Groups

(abc)       # Capture
(?:abc)     # Non-capture
(?<name>abc) # Named

4. Use

const match = str.match(/\d+/g)
const valid = /^\S+@\S+\.\S+$/.test(email)

Role: Regex Developer
Input: String + pattern
Output: Match

Patterns.

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. 6d ago First seen · 69 lines · 5 tokens per session scan A 522991630b84

Subscribe to this mod's changes

regex is a skill published in the GitHub repository dhaupin/vant (9 stars, last pushed 6d ago), licensed MIT. It adds 5 tokens to every session and 276 once invoked, about $0.0000 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 2026-08-31.

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