SubagentStart

SubagentStart is a hook for Claude Code from bjornjee/agent-dashboard. Its token cost is not measured, scanned A, original, MIT.

A subagent-start hook that runs a Node.js script whenever a delegated coding-agent worker begins. The script is part of the agent-dashboard project.

In plain words
What is it for?
Use it to track worker creation and update dashboard state when subagents are spawned.
Why use it?
It records the moment a worker starts, making delegated work visible in the dashboard.

Hook for Claude Code

Written for Claude Code: ${CLAUDE_PLUGIN_ROOT} variable. Also seen: mentions subagents.

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 agent-dashboard plugin — 8 skills, 5 agents, 10 hooks shipped together

One of 10 entries in hooks.json upstream. Installing this one merges just its entry into your config; the other 9 are separate, each on its own page.

Good fit Use it to track worker creation and update dashboard state when subagents are spawned.

Compare 6 hooks from other repositories ↓
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 bjornjee/agent-dashboard
Claude Code
/plugin install agent-dashboard

Made for: Claude Code.

Or install agent-dashboard, the plugin that ships this one along with the rest of its 8 skills, 5 agents, 10 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/bjornjee/agent-dashboard/subagent-start/github.svg)](https://agentmods.dev/hooks/bjornjee/agent-dashboard/subagent-start)
Your own site
<a href="https://agentmods.dev/hooks/bjornjee/agent-dashboard/subagent-start"><img src="https://agentmods.dev/badge/hooks/bjornjee/agent-dashboard/subagent-start/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 SubagentStart

Your own site · 80×15
<a href="https://agentmods.dev/hooks/bjornjee/agent-dashboard/subagent-start"><img src="https://agentmods.dev/badge/hooks/bjornjee/agent-dashboard/subagent-start.svg" alt="Reviewed on agentmods" width="80" 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. A grade says what 26 rules found in the file — not that it is safe.
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 1mo 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.

adapters/claude-code/hooks/hooks.json · 16 lines

What it actually says

{
  "SubagentStart": [
    {
      "matcher": "*",
      "hooks": [
        {
          "type": "command",
          "command": "node \"${CLAUDE_PLUGIN_ROOT}/scripts/hooks/agent-state-reporter.js\"",
          "async": true,
          "timeout": 5
        }
      ],
      "description": "Track subagent spawn in dashboard"
    }
  ]
}
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 · 16 lines scan A 29508f4716fb

Subscribe to this mod's changes

SubagentStart is a hook published in the GitHub repository bjornjee/agent-dashboard (26 stars, last pushed 3mo 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 2026-08-30.