SubagentStart

SubagentStart is a hook for coding agents from TerenceLiu98/prewalk. Its token cost is not measured, scanned A, original, no licence file.

A hook that runs when a matching subagent starts, including certain prewalk-executor tool calls. A subagent is a smaller agent started to handle part of a larger task.

In plain words
What is it for?
Use it to run handoff_lifecycle.py whenever the configured subagent starts.
Why use it?
It automates handoff lifecycle work at the moment the relevant subagent begins.

Hook

Part of the prewalk plugin — 9 skills, 1 agent, 8 hooks shipped together

One of 8 entries in hooks.json — they are configured in one file and arrive 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 hooks/terenceliu98/prewalk/subagent-start
Clone the repo
git clone --depth 1 https://github.com/TerenceLiu98/prewalk

Or install prewalk, the plugin that ships this one along with the rest of its 9 skills, 1 agent, 8 hooks.

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 SubagentStart

README.md
[![agentmods](https://agentmods.dev/badge/hooks/terenceliu98/prewalk/subagent-start.svg)](https://agentmods.dev/hooks/terenceliu98/prewalk/subagent-start)
Your own site
<a href="https://agentmods.dev/hooks/terenceliu98/prewalk/subagent-start"><img src="https://agentmods.dev/badge/hooks/terenceliu98/prewalk/subagent-start.svg" alt="Measured on agentmods" height="20"></a>
Per session not measured What this adds to a session before it is invoked.
When invoked not measured Not applicable: nothing here is loaded into a session.
Security scan A 0 findings. Scan, not verified.
Origin unknown No closer match found in the catalogue.
Security

Grade A, and why

SubagentStart 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 commands this hook runs, not an audit. A hook is shell that executes on your machine at the event it names, which is why every command in it is printed with what was found.

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.

claude-code/hooks/hooks.json · 14 lines

The source is not reproduced here

A licence we could not identify

The repository carries a LICENSE file, but it is custom or dual enough that GitHub cannot name it and neither can this catalogue. Unknown terms are not permission, so the body is not copied here. Read the licence at the source and decide for yourself.

Read it on GitHub

Same file

What else hooks.json configures

This page is one entry in a file that holds 8. Installing the file brings all of them; each is measured and scanned on its own page.

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 · 14 lines scan A 6485693309e2

Subscribe to this mod's changes

SubagentStart is a hook published in the GitHub repository TerenceLiu98/prewalk (4 stars, last pushed 15d ago), with no licence file. Its token cost is not measured: a hook is shell that never enters the context. 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.