SessionStart

Startup hooks are automatic commands that run when a coding session begins. These hooks check the CLI version and run a Onebrain hook.

In plain words
What is it for?
It is for checking the installed CLI version and triggering Onebrain's session-start action.
Why use it?
They automate checks and setup that would otherwise need to be run manually at the start of every session.

Hook for Claude Code

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/onebrain-ai/onebrain/session-start
Clone the repo
git clone --depth 1 https://github.com/onebrain-ai/onebrain

Made for: Claude Code.

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 58% 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 2d 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

58% identical to SessionStart — 15 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/plugins/onebrain/hooks/hooks.json · 22 lines

What it actually says

{
  "SessionStart": [
    {
      "hooks": [
        {
          "type": "command",
          "command": "bash \"${CLAUDE_PLUGIN_ROOT}/hooks/check-cli-version.sh\"",
          "timeout": 10
        }
      ]
    },
    {
      "hooks": [
        {
          "type": "command",
          "command": "onebrain hook || echo '{}'",
          "timeout": 10
        }
      ]
    }
  ]
}
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. 2d ago First seen · 22 lines scan A 47273b0d33fb

Subscribe to this mod's changes

SessionStart is a hook published in the GitHub repository onebrain-ai/onebrain (25 stars, last pushed 4d 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 58% identical to SessionStart, differing in 15 lines, and is treated as a copy.