SubagentStart

SubagentStart is a hook for Claude Code from modu-ai/moai-adk. Its token cost is not measured, scanned A, a copy of SessionStart, Apache-2.0.

A project hook that runs when a helper agent starts.

In plain words
What is it for?
Use it to run the subagent-start script whenever another agent begins work.
Why use it?
It gives the project a defined point to prepare for or record the start of delegated work.

Hook for Claude Code

One of 21 entries in settings.json — they are configured in one file and arrive together.

About the project

MoAI-ADK is a Go-based harness that organizes and verifies Claude Code work across planning, implementation, synchronization, and review stages. Developers use it to structure agentic coding tasks, apply quality gates, and route work across language models, while the catalogue entries extend its workflow with skills, hooks, commands, MCP servers, instructions, and settings.

modu-ai/moai-adk · 1,197 stars · on GitHub

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/modu-ai/moai-adk/subagent-start
Clone the repo
git clone --depth 1 https://github.com/modu-ai/moai-adk

Made for: Claude Code.

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/modu-ai/moai-adk/subagent-start.svg)](https://agentmods.dev/hooks/modu-ai/moai-adk/subagent-start)
Your own site
<a href="https://agentmods.dev/hooks/modu-ai/moai-adk/subagent-start"><img src="https://agentmods.dev/badge/hooks/modu-ai/moai-adk/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 91% 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

91% identical to SessionStart — 7 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.

.claude/settings.json · 18 lines

What it actually says

{
  "SubagentStart": [
    {
      "hooks": [
        {
          "command": "bash",
          "args": [
            "-c",
            "[ -f \"$0\" ] && exec bash \"$0\"; d=\"${0%/.claude/hooks/moai/*}\"; mkdir -p \"$d/.moai/logs\" 2>/dev/null; printf \"%s %s\\n\" \"$(date -u +%FT%TZ)\" \"hook missing: $0\" >> \"$d/.moai/logs/hook-missing.log\" 2>/dev/null; exit 0",
            "${CLAUDE_PROJECT_DIR}/.claude/hooks/moai/handle-subagent-start.sh"
          ],
          "timeout": 5,
          "type": "command"
        }
      ]
    }
  ]
}
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 · 18 lines scan A 97a3389f05cb

Subscribe to this mod's changes

SubagentStart is a hook published in the GitHub repository modu-ai/moai-adk (1,197 stars, last pushed yesterday), licensed Apache-2.0. 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 91% identical to SessionStart, differing in 7 lines, and is treated as a copy.