They prepare session-specific information without requiring a manual setup step. This can help other session tools find the current run and its transcript.

SessionStart — Hook for Claude Code by jinseo-jang

SessionStart

SessionStart is a hook for Claude Code from jinseo-jang/antigravity-plugin-cc. Its token cost is not measured, scanned A, original, Apache-2.0.

Automatic actions that run when a coding-agent session starts. These actions run a startup script and can store session and transcript paths in the session environment.

In plain words

What is it for?: Use it to run startup commands and expose the current session ID and transcript path when those values are available.
Why use it?: They prepare session-specific information without requiring a manual setup step. This can help other session tools find the current run and its transcript.

Written for Claude Code: ${CLAUDE_PLUGIN_ROOT} variable.

Runs only inside its plugin — its command needs a path that Claude Code sets for a plugin’s own hooks and for nothing else. Install the plugin, not this.

Part of the agy plugin — 11 commands, 2 hooks shipped together

One of 2 entries in hooks.json upstream. Installing this one merges just its entry into your config; the other 1 are separate, each on its own page.

Good fit Use it to run startup commands and expose the current session ID and transcript path when those values are available.

Compare 6 hooks from other repositories ↓

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 jinseo-jang/antigravity-plugin-cc

Claude Code

/plugin install agy

Made for: Claude Code.

Or install agy, the plugin that ships this one along with the rest of its 11 commands, 2 hooks.

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/jinseo-jang/antigravity-plugin-cc/session-start/github.svg)](https://agentmods.dev/hooks/jinseo-jang/antigravity-plugin-cc/session-start)

Your own site

<a href="https://agentmods.dev/hooks/jinseo-jang/antigravity-plugin-cc/session-start"><img src="https://agentmods.dev/badge/hooks/jinseo-jang/antigravity-plugin-cc/session-start/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/hooks/jinseo-jang/antigravity-plugin-cc/session-start"><img src="https://agentmods.dev/badge/hooks/jinseo-jang/antigravity-plugin-cc/session-start.svg" alt="Reviewed on agentmods" width="80" 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. A grade says what 26 rules found in the file — not that it is safe.

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 2mo 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.

plugin/hooks/hooks.json · 16 lines

What it actually says

{
  "SessionStart": [
    {
      "hooks": [
        {
          "type": "command",
          "command": "\"${CLAUDE_PLUGIN_ROOT}/hooks/session_start.sh\" || true"
        },
        {
          "type": "command",
          "command": "python3 -c \"import json,os,sys; d=json.load(sys.stdin); f=os.environ.get('CLAUDE_ENV_FILE'); open(f,'a').write('export CLAUDE_SESSION_ID=%s\\nexport CLAUDE_TRANSCRIPT_PATH=%s\\n'%(d.get('session_id',''),d.get('transcript_path',''))) if f else None\" 2>/dev/null; true"
        }
      ]
    }
  ]
}

Same file

What else `hooks.json` configures

This page is one entry in a file that holds 2. Installing the file brings all of them; each is measured and scanned on its own page.

Hook SessionEnd A not measured

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.

2mo ago First seen · 16 lines scan A 9b5a93277718

Subscribe to this mod's changes

SessionStart is a hook published in the GitHub repository jinseo-jang/antigravity-plugin-cc (6 stars, last pushed 2mo 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.

SessionStart next to 6 hooks from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
SessionStartjinseo-jang/antigravity-plugin-cc	Hook	6	2mo ago	Apache-2.0	A	—	Claude Code
SessionStartsupabase/supabase	Hook	115k	today	Apache-2.0	A	—	Claude Code
PostToolUsesupabase/supabase	Hook	115k	today	Apache-2.0	A	—	Claude Code
SessionStartgoogle-gemini/gemini-cli	Hook	109k	today	Apache-2.0	A	—	Claude Code
PreToolUseapache/superset	Hook	75k	today	Apache-2.0	A	—	Claude Code
PostToolUseanthropics/claude-plugins-official	Hook	47k	today	Apache-2.0	A	—	Claude Code
PreToolUseheygen-com/hyperframes	Hook	82k	today	Apache-2.0	A	—	Claude Code