PostToolUse

A post-edit check that runs a shell command after the agent finishes using the Edit tool.

In plain words
What is it for?
Reviewing the size of automatic code fixes and prompting a developer to verify that the change stays minimal.
Why use it?
It warns when a change affects more than one file or adds more than 20 lines, helping catch edits that may be broader than intended.

Hook for Codex

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/pproenca/dot-skills/post-tool-use
Clone the repo
git clone --depth 1 https://github.com/pproenca/dot-skills

Made for: Codex.

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

PostToolUse 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.

.agents/skills/bug-review/hooks/hooks.json · 14 lines

What it actually says

{
  "PostToolUse": [
    {
      "matcher": "Edit",
      "hooks": [
        {
          "type": "command",
          "command": "CHANGED=$(git diff --stat 2>/dev/null | tail -1); FILES=$(echo \"$CHANGED\" | grep -oE '[0-9]+ file' | grep -oE '[0-9]+'); LINES=$(echo \"$CHANGED\" | grep -oE '[0-9]+ insertion' | grep -oE '[0-9]+'); if [ \"${FILES:-0}\" -gt 1 ] || [ \"${LINES:-0}\" -gt 20 ]; then echo \"WARNING: Autofix scope exceeded (${FILES:-0} files, ${LINES:-0} insertions). Verify the change is minimal.\" >&2; fi",
          "timeout": 5
        }
      ]
    }
  ]
}
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 f2d21e17dbff

Subscribe to this mod's changes

PostToolUse is a hook published in the GitHub repository pproenca/dot-skills (200 stars, last pushed 16d 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.