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.
/plugin marketplace add penfieldlabs/claude-penfield/plugin install penfieldWrote 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.
[](https://agentmods.dev/hooks/penfieldlabs/claude-penfield/session-start)<a href="https://agentmods.dev/hooks/penfieldlabs/claude-penfield/session-start"><img src="https://agentmods.dev/badge/hooks/penfieldlabs/claude-penfield/session-start.svg" alt="Measured on agentmods" height="20"></a>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 5d 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.
This is a copy
100% identical to SessionStart — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
What it actually says
{
"SessionStart": [
{
"matcher": "startup|resume|clear|compact",
"hooks": [
{
"type": "command",
"command": "bash ${CLAUDE_PLUGIN_ROOT}/hooks/scripts/session-start.sh",
"timeout": 10
}
]
}
]
}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.
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.
- 5d ago First seen · 14 lines scan A 5e044cf8047d
SessionStart is a hook published in the GitHub repository penfieldlabs/claude-penfield (2 stars, last pushed 6mo 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. It is 100% identical to SessionStart, differing in 0 lines, and is treated as a copy.
Other hooks, from other repositories
SessionStart
Runs when a session starts on startup, clear and compact, executing session-brief.sh. From techtheist/engram.
PostToolUse
Runs after a tool call finishes for Read, Edit, Write and MultiEdit tool calls, executing file-read-match.sh. From techtheist/engram.
SessionStart
Runs when a session starts on startup, running echo 'MemoryPlugin is connected: the user has one long-term . From memoryplugin/agent-skills.
Stop
Runs when the agent finishes a response, running an inline shell check. From allenc84/sapience.
SessionStart
Runs when a session starts, running an inline shell check. From John-Daniels/lore.
Stop
Runs when the agent finishes a response, running an inline shell check. From John-Daniels/lore.