Extension: Hooks & Events

Extension: Hooks & Events is a skill for Claude Code, Codex from systempromptio/systemprompt-template. It costs 19 tokens per session (700 once invoked), scanned A, original, no licence file.

A guide to hooks and lifecycle events, including available hook points, hook scripts, and event-driven automation. A hook is code that runs when a particular action or stage occurs.

In plain words
What is it for?
Use it when adding or reviewing lifecycle hooks, event handlers, hook scripts, or other event-triggered tasks.
Why use it?
It helps developers connect automation to the right moments in the system.

Skill for Claude CodeCodex

Part of the systemprompt-dev plugin — 10 skills, 6 agents 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/systempromptio/systemprompt-template/dev-ext-hooks
Any agent
npx skills add systempromptio/systemprompt-template --skill dev-ext-hooks
Clone the repo
git clone --depth 1 https://github.com/systempromptio/systemprompt-template

Made for: Claude Code, Codex.

Or install systemprompt-dev, the plugin that ships this one along with the rest of its 10 skills, 6 agents.

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 Extension: Hooks & Events

README.md
[![agentmods](https://agentmods.dev/badge/skills/systempromptio/systemprompt-template/dev-ext-hooks.svg)](https://agentmods.dev/skills/systempromptio/systemprompt-template/dev-ext-hooks)
Your own site
<a href="https://agentmods.dev/skills/systempromptio/systemprompt-template/dev-ext-hooks"><img src="https://agentmods.dev/badge/skills/systempromptio/systemprompt-template/dev-ext-hooks.svg" alt="Measured on agentmods" height="20"></a>
Per session 19 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 700 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00019 $0.00700
Opus 5 $0.00010 $0.00350
Sonnet 5 $0.00004 $0.00140
Haiku 4.5 $0.00002 $0.00070

Measured 4d ago against content hash dee186771f8e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

Extension: Hooks & Events 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 4d 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.

storage/files/plugins/systemprompt-dev/skills/dev-ext-hooks/SKILL.md · 116 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

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. 4d ago First seen · 116 lines · 19 tokens per session scan A dee186771f8e

Subscribe to this mod's changes

Extension: Hooks & Events is a skill published in the GitHub repository systempromptio/systemprompt-template (28 stars, last pushed yesterday), with no licence file. It adds 19 tokens to every session and 700 once invoked, about $0.0001 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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