What is SubagentStart?

A startup hook that runs a shell script whenever a subagent begins. A subagent is a separate assistant process working on part of a task.

Use it to run the specified subagent-start script whenever a subagent is launched.

It automates setup or other actions at the start of each subagent session.

SubagentStart — Hook by bhpascal

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/bhpascal/personality-roulette/subagent-start

Clone the repo

git clone --depth 1 https://github.com/bhpascal/personality-roulette

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 61% 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 yesterday.

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

61% identical to SessionStart — 8 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 · 13 lines

What it actually says

{
  "SubagentStart": [
    {
      "matcher": ".*",
      "hooks": [
        {
          "type": "command",
          "command": "$CLAUDE_PLUGIN_ROOT/hooks-handlers/subagent-start.sh"
        }
      ]
    }
  ]
}

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.

yesterday First seen · 13 lines scan A e7d6d5e589b0

Subscribe to this mod's changes

SubagentStart is a hook published in the GitHub repository bhpascal/personality-roulette (4 stars, last pushed 5mo 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 61% identical to SessionStart, differing in 8 lines, and is treated as a copy.

Building agents Planning ai claude-code cli personality plugin

SubagentStart

Getting it into your agent

Grade A, and why

Nothing flagged

This is a copy

What it actually says

What this file has done since we first saw it

Other hooks, from other repositories

SubagentStop

SubagentStart

SubagentStop

SubagentStop

SubagentStop

SubagentStop