What is SessionStart?

A session-start hook that runs initialization and automatic-capture scripts when an agent session begins. A hook is an automatic command attached to a lifecycle event.

Use it to run first-time setup and automatic capture when a new session starts.

It performs the listed setup and capture tasks at the start of every session without a manual command.

SessionStart — Hook by anthonysuherli

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/anthonysuherli/br8n/session-start

Clone the repo

git clone --depth 1 https://github.com/anthonysuherli/br8n

Or install br8n, the plugin that ships this one along with the rest of its 11 skills, 3 hooks, 1 MCP server.

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 92% 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

92% identical to UserPromptSubmit — 11 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 · 19 lines

What it actually says

{
  "SessionStart": [
    {
      "matcher": "*",
      "hooks": [
        {
          "type": "command",
          "command": "${CLAUDE_PLUGIN_ROOT}/bin/br8n-python ${CLAUDE_PLUGIN_ROOT}/hooks/first-run-init.py",
          "timeout": 30
        },
        {
          "type": "command",
          "command": "${CLAUDE_PLUGIN_ROOT}/bin/br8n-python ${CLAUDE_PLUGIN_ROOT}/hooks/auto-capture.py",
          "timeout": 30
        }
      ]
    }
  ]
}

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.

2d ago First seen · 19 lines scan A bbabe77dbd25

Subscribe to this mod's changes

SessionStart is a hook published in the GitHub repository anthonysuherli/br8n (1 stars, last pushed 1mo 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 92% identical to UserPromptSubmit, differing in 11 lines, and is treated as a copy.

claude-code context-engineering developer-tools knowledge-base mcp

SessionStart

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

SessionStart

SubagentStop

StopFailure

SessionEnd

PreCompact

PreCompact