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.
/plugin marketplace add SenMuShare/senmu-buildos/plugin install senmu-buildosWrote 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.
[](https://agentmods.dev/hooks/senmushare/senmu-buildos/subagent-start)<a href="https://agentmods.dev/hooks/senmushare/senmu-buildos/subagent-start"><img src="https://agentmods.dev/badge/hooks/senmushare/senmu-buildos/subagent-start.svg" alt="Measured on agentmods" height="20"></a>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 6d 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.
What it actually says
{
"SubagentStart": [
{
"hooks": [
{
"type": "command",
"command": "node \"${CLAUDE_PLUGIN_ROOT}/adapters/claude-code/hooks/subagent-start.js\"",
"timeout": 5
}
]
}
]
}What else hooks.json configures
This page is one entry in a file that holds 2. Installing the file brings all of them; each is measured and scanned on its own page.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 6d ago First seen · 13 lines scan A 919ec3bc200d
SubagentStart is a hook published in the GitHub repository SenMuShare/senmu-buildos (2 stars, last pushed yesterday), licensed Apache-2.0. Its token cost is not measured: a hook is shell that never enters the context. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
Other hooks, from other repositories
PostToolUse
Runs after a tool call finishes for ^mcp__ambient_project__(list_projects, record_project_events, acknowledge_no_project_events, decline_project_binding and restore_project_binding)$ tool calls, executing index.js. From Bene-2020/plane-codex-mcp.
SessionStart
Runs when a session starts on startup, resume, clear and compact, executing index.js. From Bene-2020/plane-codex-mcp.
SessionEnd
Runs when a session ends for ^other$ tool calls, executing index.js. From Bene-2020/plane-codex-mcp.
UserPromptSubmit
Runs when you submit a prompt, before the agent sees it, executing index.js. From Bene-2020/plane-codex-mcp.
Stop
Runs when the agent finishes a response, executing index.js. From Bene-2020/plane-codex-mcp.
SessionStart
Runs when a session starts, executing session-lifecycle-hook.mjs via node. From sendbird/cc-plugin-codex.