agentmods.dev

SessionStart

A session-start hook that runs a Node.js script automatically when a session begins.

In plain words
What is it for?
Use it to run setup or initialization logic when a Gemini CLI session opens.
Why use it?
It removes the need to remember a startup command for work that should happen at the beginning of every session.

Hook

107k 2d ago A scan tokens not measured original Apache-2.0
View the source file google-gemini/gemini-cli
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/google-gemini/gemini-cli/session-start
Clone the repo
git clone --depth 1 https://github.com/google-gemini/gemini-cli
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.

Origin

Copies of this mod

3 near-identical copies found in the catalogue:

packages/cli/src/commands/extensions/examples/hooks/hooks/hooks.json · 12 lines

What it actually says

{
  "SessionStart": [
    {
      "hooks": [
        {
          "type": "command",
          "command": "node ${extensionPath}/scripts/on-start.js"
        }
      ]
    }
  ]
}
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 · 12 lines scan A 30141bc1a11c

Subscribe to this mod's changes

SessionStart is a hook published in the GitHub repository google-gemini/gemini-cli (106,749 stars, last pushed 2d 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 2026-08-30.

Backend and APIsaiai-agentscligeminigemini-apimcp-client
Related

Other hooks, from other repositories

SessionStart

Runs when a session starts, executing check_env.py via python. From Ibrahim-3d/nano-banana-claude-plugin.

Ibrahim-3d/nano-banana-claude-plugin · not measured

PostToolUse

Runs after a tool call finishes for Edit and Write tool calls, executing cli.js. From tw93/Pake.

tw93/Pake · not measured

SessionStart

Runs when a session starts on startup, executing claude-dev-setup-once.sh. From burin-labs/harn.

burin-labs/harn · 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

SessionEnd

Runs when a session ends, running an inline shell check. From bhargavamin/contexer.

bhargavamin/contexer · not measured

AfterAgent

Runs on the AfterAgent event, executing phase-gate.js and ralph-retry.js via node (2 commands). From richardcb/oh-my-gemini.

richardcb/oh-my-gemini · not measured