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SubagentStart

SubagentStart is a hook for Claude Code from zstevovich/claude-apd. Its token cost is not measured, scanned A, a copy of SessionStart, MIT.

A startup hook that runs a Bash script when a subagent begins. A subagent is a smaller coding agent assigned part of a larger task.

In plain words
What is it for?
Tracking or preparing subagents at the moment they begin work.
Why use it?
It lets the project perform a setup or tracking action automatically whenever a subagent starts.

Hook for Claude Code

Written for Claude Code: ${CLAUDE_PLUGIN_ROOT} variable.

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 claude-apd plugin — 11 skills, 5 agents, 8 hooks, 1 MCP server shipped together

One of 8 entries in hooks.json — they are configured in one file and arrive together.

not rated 5 1mo ago A scan tokens not measured copy · 86% MIT
View the source file zstevovich/claude-apd
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 zstevovich/claude-apd
Claude Code
/plugin install claude-apd

Made for: Claude Code.

Or install claude-apd, the plugin that ships this one along with the rest of its 11 skills, 5 agents, 8 hooks, 1 MCP server.

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/zstevovich/claude-apd/subagent-start.svg)](https://agentmods.dev/hooks/zstevovich/claude-apd/subagent-start)
Your own site
<a href="https://agentmods.dev/hooks/zstevovich/claude-apd/subagent-start"><img src="https://agentmods.dev/badge/hooks/zstevovich/claude-apd/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 86% copy Near-identical to another mod 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 5d 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.

Origin

This is a copy

86% identical to SessionStart — 9 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

hooks/hooks.json · 16 lines

What it actually says

{
  "SubagentStart": [
    {
      "hooks": [
        {
          "type": "command",
          "command": "bash",
          "args": [
            "${CLAUDE_PLUGIN_ROOT}/plugins/apd/bin/adapter/cc/track-agent"
          ],
          "timeout": 3
        }
      ]
    }
  ]
}
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. 5d ago First seen · 16 lines scan A e065dac1394f

Subscribe to this mod's changes

SubagentStart is a hook published in the GitHub repository zstevovich/claude-apd (5 stars, last pushed 1mo 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. It is 86% identical to SessionStart, differing in 9 lines, and is treated as a copy.

Related

Other hooks, from other repositories

PostToolUse

Runs after a tool call finishes for Write and Edit tool calls, executing format_and_lint.sh. From supabase/supabase.

supabase/supabase · not measured

SessionStart

Runs when a session starts, executing on-start.js via node. From google-gemini/gemini-cli.

google-gemini/gemini-cli · not measured

SessionStart

Runs when a session starts on startup, executing install_pkgs.sh. From supabase/supabase.

supabase/supabase · not measured

PreToolUse

Runs before the agent uses a tool for Bash tool calls, running an inline shell check. From apache/superset.

apache/superset · not measured

PreToolUse

Runs before the agent uses a tool, executing pre-write.sh and pre-bash.sh (2 commands). From anthropics/claude-cookbooks.

anthropics/claude-cookbooks · not measured

SessionStart

Runs when a session starts, executing session-start.sh. From anthropics/claude-cookbooks.

anthropics/claude-cookbooks · not measured