agentmods.dev

SessionStart

A session-start hook that runs a shell command when a coding-agent session begins. A shell command is a line of text executed by the operating system.

In plain words
What is it for?
Use it to list skills in the user or project Claude skills directories at the beginning of each session.
Why use it?
It automatically shows which skills are installed, so you do not have to check those folders yourself.

Hook for Claude Code

5 7d ago B scan tokens not measured original CC0-1.0
View the source file ahgraber/skills
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/ahgraber/skills/session-start
Clone the repo
git clone --depth 1 https://github.com/ahgraber/skills

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 B 1 finding. Scan, not verified.
Origin original No closer match found in the catalogue.
Security

Grade B, and why

SessionStart scanned grade B with 1 finding 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.

Enumerates other installed skillsmediumAgent snooping

Other skills' SKILL.md files reveal prompts, capabilities and secrets that should be invisible to peers.

"command": "echo 'Installed skills:'; ls ~/.claude/skills/ 2>/dev/null; ls .claude/skills/ 2>/dev/null"
.claude/settings.json · 12 lines

What it actually says

{
  "SessionStart": [
    {
      "hooks": [
        {
          "type": "command",
          "command": "echo 'Installed skills:'; ls ~/.claude/skills/ 2>/dev/null; ls .claude/skills/ 2>/dev/null"
        }
      ]
    }
  ]
}
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 · 12 lines scan B 1b21f4964705

Subscribe to this mod's changes

SessionStart is a hook published in the GitHub repository ahgraber/skills (5 stars, last pushed 7d ago), licensed CC0-1.0. Its token cost is not measured: a hook is shell that never enters the context. A static security scan graded it B with 1 finding (enumerates other installed skills). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

agent-skills
Related

Other hooks, from other repositories

PostToolUse

Runs after a tool call finishes for Write and Edit tool calls, executing format_and_lint.sh. From supabase/supabase.

supabase/supabase · not measured

SessionStart

Runs when a session starts, executing on-start.js via node. From google-gemini/gemini-cli.

google-gemini/gemini-cli · not measured

SessionStart

Runs when a session starts on startup, executing install_pkgs.sh. From supabase/supabase.

supabase/supabase · not measured

PreToolUse

Runs before the agent uses a tool, executing pre-write.sh and pre-bash.sh (2 commands). From anthropics/claude-cookbooks.

anthropics/claude-cookbooks · not measured

SessionStart

Runs when a session starts, executing session-start.sh. From anthropics/claude-cookbooks.

anthropics/claude-cookbooks · not measured

SessionStart

Runs when a session starts on startup, clear and compact, executing run-hook.cmd. From obra/superpowers.

obra/superpowers · not measured