Add optional Claude Code hook for blocking malicious packages

[David Larsen (dc-larsen)]

Summary

Adds a PreToolUse hook (hooks/socket-gate.ts) for Claude Code that intercepts package install commands and queries the public Socket MCP server before allowing installation.

• Blocks packages with supply chain score below 20 (known malware, typosquats, high-risk signals)
• Supports npm, PyPI, Cargo, RubyGems, Go, and NuGet ecosystems
• No API key, no CLI, no registration — uses https://mcp.socket.dev/ directly
• Fails open on network, parse, and timeout errors so a Socket outage never blocks legitimate work
• Standalone Node.js script using --experimental-strip-types — no build step, no extra deps

Replaces #168 (which used the Socket CLI + API key). Design simplified after review feedback.

Files

File	Description
hooks/socket-gate.ts	The hook script
hooks/socket-gate.test.ts	23 tests (8 unit, 15 integration)
README.md	Setup and usage docs under "Claude Code Hook (Optional)"

Supported commands

Ecosystem	Commands
npm	npm install, npm i, npm add, yarn add, pnpm add, bun add
PyPI	pip install, pip3 install, uv add, uv pip install, poetry add, pipenv install
Cargo	cargo add, cargo install
RubyGems	gem install, bundle add
Go	go get, go install
NuGet	dotnet add package, nuget install

How it works

1. Claude Code emits a PreToolUse JSON payload on stdin for every Bash call
2. The hook extracts the package name from recognized install commands
3. It POSTs an MCP initialize then a tools/call for the depscore tool against https://mcp.socket.dev/
4. If supplyChain < 20, it returns deny with a reason that includes the score and a socket.dev review link
5. Anything else (unrecognized command, non-install, network error, parse error) returns allow

Test results

ℹ tests 23
ℹ pass 23
ℹ fail 0

Inspired by Jimmy Vo's dependency hook.

[John-David Dalton (jdalton)]

Landed in main as part of ae237a0 (feat(hooks): add optional socket-gate Claude Code hook + Factory install docs), with you credited as co-author. The hook carried over as hooks/socket-gate.ts, adapted to fleet conventions (exported helpers, undefined-over-null, sorted methods), and the test was re-implemented as test/socket-gate.test.ts under vitest with a stubbed fetch (no live network) covering the parsers + allow/deny/error decisions. Verified running live against the public server. Thanks — nice guardrail!