SessionStart

SessionStart is a hook for coding agents from vsladkov/claudex-stereo. Its token cost is not measured, scanned A, a copy of SessionStart, Apache-2.0.

A session-start hook that runs a JavaScript file with Node.js whenever a Claude Code session begins.

In plain words
What is it for?
Use it to trigger the session-lifecycle-hook.cjs script at startup. The hook has a five-second timeout.
Why use it?
It provides an automatic action at the beginning of each session without requiring you to run the script yourself.

Hook

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 stereo plugin — 4 skills, 15 commands, 7 agents, 3 hooks shipped together

One of 3 entries in hooks.json — they are configured in one file and arrive together.

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 vsladkov/claudex-stereo
Claude Code
/plugin install stereo

Or install stereo, the plugin that ships this one along with the rest of its 4 skills, 15 commands, 7 agents, 3 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 SessionStart

README.md
[![agentmods](https://agentmods.dev/badge/hooks/vsladkov/claudex-stereo/session-start.svg)](https://agentmods.dev/hooks/vsladkov/claudex-stereo/session-start)
Your own site
<a href="https://agentmods.dev/hooks/vsladkov/claudex-stereo/session-start"><img src="https://agentmods.dev/badge/hooks/vsladkov/claudex-stereo/session-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 55% copy Near-identical to another mod in the catalogue.
Security

Grade A, and why

SessionStart 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 3d 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

55% identical to SessionStart — 6 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.

plugins/stereo/hooks/hooks.json · 13 lines

What it actually says

{
  "SessionStart": [
    {
      "hooks": [
        {
          "type": "command",
          "command": "node \"${CLAUDE_PLUGIN_ROOT}/scripts/session-lifecycle-hook.cjs\" SessionStart",
          "timeout": 5
        }
      ]
    }
  ]
}
Same file

What else hooks.json configures

This page is one entry in a file that holds 3. 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. 3d ago First seen · 13 lines scan A 8c0b8a68df08

Subscribe to this mod's changes

SessionStart is a hook published in the GitHub repository vsladkov/claudex-stereo (3 stars, last pushed 25d ago), 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 55% identical to SessionStart, differing in 6 lines, and is treated as a copy.