regex

regex is a skill for Claude Code from AntheaLaffy/the-missing-semester-skills. It costs 62 tokens per session (863 once invoked), scanned A, original, no licence file.

A guide to regular expressions, which are patterns used to find, extract, or replace text. It covers building blocks, capture groups, references, greedy matching, and important limits.

In plain words
What is it for?
It helps create and explain regexes, use captured text in replacements, understand matching pitfalls, and decide when another approach is needed.
Why use it?
It helps avoid hard-to-read or incorrect text patterns, especially when matching rules become more complex than simple searches.

Skill for Claude Code

Written for Claude Code: disable-model-invocation in frontmatter.

Good fit It helps create and explain regexes, use captured text in replacements, understand matching pitfalls, and decide when another approach is needed.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/anthealaffy/the-missing-semester-skills/regex
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 AntheaLaffy/the-missing-semester-skills --skill regex
Clone the repo
git clone --depth 1 https://github.com/AntheaLaffy/the-missing-semester-skills

Made for: Claude Code.

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/anthealaffy/the-missing-semester-skills/regex/github.svg)](https://agentmods.dev/skills/anthealaffy/the-missing-semester-skills/regex)
Your own site
<a href="https://agentmods.dev/skills/anthealaffy/the-missing-semester-skills/regex"><img src="https://agentmods.dev/badge/skills/anthealaffy/the-missing-semester-skills/regex/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 regex

Your own site · 80×15
<a href="https://agentmods.dev/skills/anthealaffy/the-missing-semester-skills/regex"><img src="https://agentmods.dev/badge/skills/anthealaffy/the-missing-semester-skills/regex.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 62 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 863 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.
Origin unknown 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 $0.00062 $0.00863
Opus 5.5 $0.00025 $0.00345
Sonnet 5.5 $0.00012 $0.00173
Haiku 4.5 $0.00006 $0.00086

Measured 1mo ago against content hash 9ddb3af5fb08, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, 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 1mo 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.

regex/SKILL.md · 38 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

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. 1mo ago First seen · 38 lines · 62 tokens per session scan A 9ddb3af5fb08

Subscribe to this mod's changes

regex is a skill published in the GitHub repository AntheaLaffy/the-missing-semester-skills (1 stars, last pushed 1mo ago), with no licence file. It adds 62 tokens to every session and 863 once invoked, about $0.0002 per session on Opus 5.5. 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.

Related

Other skills, from other repositories

plumb-line-method

Use when an edit would make the system look more real, finished or certain than it is, to make the honest version instead: a failing test or red CI that cannot honestly pass (a dependency down, a bar missed, nobody knows why) under pressure to get it green anyway; a fallback, fixture or generated value passed off as…

slopstopper/plumb-line · 194 tokens

plumb-line-remediate

Use when applying findings from a plumb-line audit report — the builder has a report (or pasted findings) and wants the fixes made. Opt-in and separate from the audit, which is read-only and never fixes.

slopstopper/plumb-line · 51 tokens

audit-quality-gates

Use this skill when the user wants to audit how a project configures its style checkers and static analyzers.

yegor256/purist · 29 tokens

craft-fix

The Craftsman standard for driving fixes against an existing craft-audit workspace — "fix the findings", "fix SEC-003", "work through the audit", "start the climb". An ACTION skill, not a domain: it picks findings off the master tracker's climb sequence, re-verifies each is still real, gets the user's approval, and…

gul-labs/craftsman-marketplace · 182 tokens

matlab-coach-debugging

Use when tutoring a learner through MATLAB debugging, error interpretation, failed tests, incorrect outputs, array-shape problems, indexing mistakes, function argument issues, or code repair practice. Use for guided debugging sessions, debugging drills, teach-the-agent critique, and evidence-based MATLAB…

matlab/agent-skills-playground · 62 tokens

deslop

Audit and harden existing codebases (especially AI-generated / vibe-coded ones) for production readiness. Use when the user asks to review, audit, clean up, harden, deslop, refactor, or fix quality issues across an existing codebase. Works in two phases — first a thorough multi-pass audit written to a structured file…

thtskaran/claude-skills · 103 tokens