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SubagentStart

SubagentStart is a hook for coding agents from mgd34msu/goodvibes-plugin. Its token cost is not measured, scanned A, original, MIT.

A hook configuration that runs a Node.js script whenever a subagent starts. A subagent is a separate helper agent working on part of a larger task.

In plain words
What is it for?
Use it to trigger the configured subagent-start script at every subagent launch.
Why use it?
It allows a project to perform an automatic setup or notification at the moment a helper agent begins.

Hook

Runs only inside its plugin — its command needs a path that Claude Code sets for a plugin’s own hooks and for nothing else. Install the plugin, not this.

Part of the goodvibes plugin — 6 skills, 5 commands, 4 agents, 9 hooks, 3 MCP servers shipped together

One of 9 entries in hooks.json — they are configured in one file and arrive together.

not rated 6 10d ago A scan tokens not measured original MIT
View the source file mgd34msu/goodvibes-plugin
Install

Getting it into your agent

This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.

Claude Code
/plugin marketplace add mgd34msu/goodvibes-plugin
Claude Code
/plugin install goodvibes

Or install goodvibes, the plugin that ships this one along with the rest of its 6 skills, 5 commands, 4 agents, 9 hooks, 3 MCP servers.

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/mgd34msu/goodvibes-plugin/subagent-start.svg)](https://agentmods.dev/hooks/mgd34msu/goodvibes-plugin/subagent-start)
Your own site
<a href="https://agentmods.dev/hooks/mgd34msu/goodvibes-plugin/subagent-start"><img src="https://agentmods.dev/badge/hooks/mgd34msu/goodvibes-plugin/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 original 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 3d 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.

plugins/goodvibes/hooks/hooks.json · 14 lines

What it actually says

{
  "SubagentStart": [
    {
      "matcher": "*",
      "hooks": [
        {
          "type": "command",
          "command": "node \"${CLAUDE_PLUGIN_ROOT}/hooks/subagent-start.mjs\"",
          "timeout": 10
        }
      ]
    }
  ]
}
Same file

What else hooks.json configures

This page is one entry in a file that holds 9. 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. 3d ago First seen · 14 lines scan A c2f4ffe0d2c3

Subscribe to this mod's changes

SubagentStart is a hook published in the GitHub repository mgd34msu/goodvibes-plugin (6 stars, last pushed 10d ago), licensed MIT. 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.

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