What is SessionStart?

A startup hook that runs three shell commands when a coding session starts, is cleared, or is compacted. It displays rule files and checks that the session's operating rules are visible.

Use it to show Markdown rule files, check them on Windows or Unix-like systems, and signal when another rule-loading step may be needed.

It helps load project rules at important session transitions and points out when those rules may not be available.

SessionStart — Hook for coding agents by isvlasov: A startup hook that runs three shell commands when…

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 isvlasov/rageatc-oss

Claude Code

/plugin install rageatc-code-oss

Or install rageatc-code-oss, the plugin that ships this one along with the rest of its 21 skills, 5 agents, 1 hook.

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.

README.md

[![agentmods](https://agentmods.dev/badge/hooks/isvlasov/rageatc-oss/session-start.svg)](https://agentmods.dev/hooks/isvlasov/rageatc-oss/session-start)

Your own site

<a href="https://agentmods.dev/hooks/isvlasov/rageatc-oss/session-start"><img src="https://agentmods.dev/badge/hooks/isvlasov/rageatc-oss/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 original No closer match found 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 4d 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.

plugins/rageatc-code-oss/hooks/hooks.json · 21 lines

What it actually says

{
  "SessionStart": [
    {
      "matcher": "startup|clear|compact",
      "hooks": [
        {
          "type": "command",
          "command": "cat \"${CLAUDE_PLUGIN_ROOT}/rules/\"*.md"
        },
        {
          "type": "command",
          "command": "type \"%CLAUDE_PLUGIN_ROOT%\\rules\\*.md\""
        },
        {
          "type": "command",
          "command": "echo rageatc-code-oss failsafe: if the rageatc-code-oss operating rules are not visible in this hook output, invoke the rageatc-code-oss:loading-rules skill to load them before proceeding."
        }
      ]
    }
  ]
}

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.

4d ago First seen · 21 lines scan A f5dd36f21bfa

Subscribe to this mod's changes

SessionStart is a hook published in the GitHub repository isvlasov/rageatc-oss (9 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. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

claude-agents claude-code claude-code-plugin claude-skills

SessionStart

Getting it into your agent

Wrote this? Show the measurements

Grade A, and why

Nothing flagged

What it actually says

What this file has done since we first saw it

Other hooks, from other repositories

SubagentStop

SubagentStart

PostToolUse

PreToolUse

SessionEnd

PostToolUse