agentmods.dev

SessionStart

A session-start hook that runs a Node.js command when a new coding-agent session begins.

In plain words
What is it for?
Running startup checks or loading repository-specific instructions when a session opens.
Why use it?
It can load project rules at the start of every session, before you begin asking the agent to make changes.

Hook

11 4d ago A scan tokens not measured original MIT
View the source file code-yeongyu/codex-rules
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/code-yeongyu/codex-rules/session-start
Clone the repo
git clone --depth 1 https://github.com/code-yeongyu/codex-rules
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 yesterday.

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.

hooks/hooks.json · 14 lines

What it actually says

{
  "SessionStart": [
    {
      "hooks": [
        {
          "type": "command",
          "command": "node \"${PLUGIN_ROOT}/dist/cli.js\" hook session-start",
          "timeout": 10,
          "statusMessage": "loading project rules"
        }
      ]
    }
  ]
}
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. yesterday First seen · 14 lines scan A bb86097278dd

Subscribe to this mod's changes

SessionStart is a hook published in the GitHub repository code-yeongyu/codex-rules (11 stars, last pushed 4d 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 2026-08-30.

LanguagesSecurityagents-mdcodexcodex-plugincontext-injectionhooksrules
Related

Other hooks, from other repositories

SessionStart

Runs when a session starts on startup, resume and clear, executing run_component_hook.py via python3. From qingye-lab/rootloom.

qingye-lab/rootloom · not measured

PostToolUse

Runs after a tool call finishes, executing run.sh. From nikshepsvn/scrim.

nikshepsvn/scrim · not measured

BeforeTool

Runs on the BeforeTool event, running npx -y cc-safety-net hook --gemini-cli. From kenryu42/gemini-safety-net.

kenryu42/gemini-safety-net · not measured

PostToolUse

Runs after a tool call finishes for Write, Edit and NotebookEdit tool calls, executing batou-hook.sh. From turenlabs/batou.

turenlabs/batou · not measured

PreCompact

Runs before the context is compacted, executing checkpoint.js via node. From yanfeid/claude-amber.

yanfeid/claude-amber · not measured

Stop

Runs when the agent finishes a response, executing notify.ps1. From enescaakir/notify.

enescaakir/notify · not measured