What is SessionStart?

A session-start hook that runs a Python script when an AI session starts, resumes, or is cleared or compacted. It restores an optional context map for the session.

Use it to restore session notes and context automatically during startup, resume, clear, or compact events.

It helps the assistant recover useful project context after starting again or reducing the conversation history.

SessionStart — Hook by phenomenoner

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/phenomenoner/chatgpt-codex-app-plus/session-start

Clone the repo

git clone --depth 1 https://github.com/phenomenoner/Chatgpt-Codex-App-Plus

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.

plugins/context-canvas-codex/hooks/hooks.json · 17 lines

What it actually says

{
  "SessionStart": [
    {
      "matcher": "^(startup|resume|clear|compact)$",
      "hooks": [
        {
          "type": "command",
          "command": "python3 -I \"${PLUGIN_ROOT}/scripts/context_canvas.py\" hook-session-start",
          "commandWindows": "python -I \"$env:PLUGIN_ROOT\\scripts\\context_canvas.py\" hook-session-start",
          "timeout": 10,
          "statusMessage": "Restoring optional Context Canvas map",
          "additionalContextLimit": 5000
        }
      ]
    }
  ]
}

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.

2d ago First seen · 17 lines scan A 99c3be9ee62c

Subscribe to this mod's changes

SessionStart is a hook published in the GitHub repository phenomenoner/Chatgpt-Codex-App-Plus (2 stars, last pushed 7d 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 2026-08-31.

Code review Languages Productivity agent-tools ai-agents automation chatgpt codex-cli

SessionStart

Getting it into your agent

Grade A, and why

Nothing flagged

What it actually says

What this file has done since we first saw it

Other hooks, from other repositories

UserPromptSubmit

PreToolUse

PostToolUse

PreCompact

PostCompact

Stop