agentmods.dev

SessionStart

A session-start hook that runs a Python check whenever a new session begins. A hook is an automatic command connected to a lifecycle event.

In plain words
What is it for?
It is for launching session-start-check.py at the beginning of a session within the project.
Why use it?
It ensures the configured session-start check runs consistently instead of relying on someone to remember it manually.

Hook for Claude Code

8 18d ago A scan tokens not measured original Apache-2.0
View the source file SummerSec/SumSec-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/summersec/sumsec-skills/session-start
Clone the repo
git clone --depth 1 https://github.com/SummerSec/SumSec-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 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 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.

.claude/settings.json · 13 lines

What it actually says

{
  "SessionStart": [
    {
      "hooks": [
        {
          "type": "command",
          "command": "python3 ${CLAUDE_PROJECT_DIR}/.claude/skills/sync-skills/scripts/session-start-check.py",
          "timeout": 20
        }
      ]
    }
  ]
}
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 · 13 lines scan A 939b5ddaadb7

Subscribe to this mod's changes

SessionStart is a hook published in the GitHub repository SummerSec/SumSec-Skills (8 stars, last pushed 18d 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. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Languagesdsh-plugin
Related

Other hooks, from other repositories

SessionStart

Runs when a session starts, executing session-start.sh. From mem9-ai/mem9.

mem9-ai/mem9 · not measured

SessionEnd

Runs when a session ends, executing session-end.sh. From mem9-ai/mem9.

mem9-ai/mem9 · not measured

Stop

Runs when the agent finishes a response, executing on-stop.sh via bash. From reatcat/l123-harness.

reatcat/l123-harness · not measured

SessionStart

Runs when a session starts, executing session-start.cjs via node. From taptap/instant-games-open-mcp.

taptap/instant-games-open-mcp · not measured

SessionStart

Runs when a session starts, executing inject-instructions.mjs via node. From geml-spec/geml.

geml-spec/geml · not measured

PreToolUse

Runs before the agent uses a tool for Write and Edit tool calls, executing pre-tool-use.js via node. From SummerSec/semantic-linter.

SummerSec/semantic-linter · not measured