Use it to guard Edit and Write tool calls in the TabMerger project.

It can warn or stop the agent before changes that need extra care are made.

How lbragile/TabMerger configures Claude Code

TabMerger: Hook for Claude Code

.claude/settings.json

PreToolUse is a hook for Claude Code from lbragile/TabMerger. Its token cost is not measured, scanned A, original, no licence file.

A pre-action hook that runs protection and reminder scripts before the agent edits or writes files. It checks database migrations, automation workflows, and shared interface changes.

In plain words

What is it for?: Use it to guard Edit and Write tool calls in the TabMerger project.
Why use it?: It can warn or stop the agent before changes that need extra care are made.

Written for Claude Code: installed under .claude/.

This is lbragile/TabMerger's own configuration. It tells Claude Code how to work on TabMerger itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything TabMerger configures →

One of 3 entries in settings.json upstream. Installing this one merges just its entry into your config; the other 2 are separate, each on its own page.

Reuse

Borrowing it

Nothing to install: this file belongs to lbragile/TabMerger. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/lbragile/TabMerger/main/.claude/settings.json

Clone the repo

git clone --depth 1 https://github.com/lbragile/TabMerger

Made for: Claude Code.

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/lbragile/tabmerger/pre-tool-use/github.svg)](https://agentmods.dev/hooks/lbragile/tabmerger/pre-tool-use)

Your own site

<a href="https://agentmods.dev/hooks/lbragile/tabmerger/pre-tool-use"><img src="https://agentmods.dev/badge/hooks/lbragile/tabmerger/pre-tool-use/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/lbragile/tabmerger/pre-tool-use"><img src="https://agentmods.dev/badge/hooks/lbragile/tabmerger/pre-tool-use.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 1 finding. A grade says what 26 rules found in the file — not that it is safe.

Origin unknown No closer match found in the catalogue.

Security

Grade A, and why

PreToolUse scanned grade A with 1 finding 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.

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

"command": "python3 -c \"import sys,os,subprocess; data=sys.stdin.buffer.read(); root=subprocess.run(['git','rev-parse','--show-toplevel'],capture_output=True,text=True).stdout.strip(); sys.stdin=__import__('io').TextIOW

.claude/settings.json · 25 lines

The source is not reproduced here

A licence we could not identify

The repository carries a LICENSE file, but it is custom or dual enough that GitHub cannot name it and neither can this catalogue. Unknown terms are not permission, so the body is not copied here. Read the licence at the source and decide for yourself.

Read it on GitHub

Same file

What else `settings.json` configures

This page is one entry in a file that holds 3. Installing the file brings all of them; each is measured and scanned on its own page.

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.

yesterday First seen · 25 lines scan A e5cf0ecafcce

Subscribe to this mod's changes

PreToolUse is a hook published in the GitHub repository lbragile/TabMerger (192 stars, last pushed today), with no licence file. Its token cost is not measured: a hook is shell that never enters the context. A static security scan graded it A with 1 finding (runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-11-07.

Security chrome-extension edge-extension firefox-extension tab-management

PreToolUse next to 6 hooks from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
PreToolUselbragile/TabMerger	Hook	192	today	none	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	yesterday	Apache-2.0	A	—	Claude Code
PostToolUseanthropics/claude-plugins-official	Hook	46k	yesterday	Apache-2.0	A	—	Claude Code
PreToolUseanthropics/claude-cookbooks	Hook	54k	3d ago	MIT	A	—	Claude Code