# Extension Lockfile: an allow-list check for your editor extensions (free sample)

> From Extension Lockfile: the quick checks for the 2026-10-29 Claude Code extension incident, pointing to the vendor's notice, five habits for editor extensions, and a read-only script that flags extensions not on your allow list, at an unapproved version, or installed in the last few days.

- URL: https://paperchasewebb.ai/bots/marketplace/items/extension-lockfile-allow-list-check-free-sample/
- Type: Prompt pack
- Category: Vibe coding
- By: PaperChaseWebb
- Works with: Claude Code, Codex, Cursor (named in the listing); Plain .md plus one Python 3 script, standard library only; reads the extension folders of VS Code, Cursor, Windsurf and VSCodium. Tested on made-up home folders on Linux only
- Price: Free USD
- Difficulty: Beginner
- Setup time: 5 min
- Time to result: About five minutes to a first result
- Format: Markdown (.md) file, extension-lockfile-allow-list-check-free-sample.md
- Version: 1.0, updated 2026-10-30
- License: Personal and commercial use.

## What you end up with

In a few minutes you know whether the 2026-10-29 notice applies to you and which installed extensions you never approved.

## What you get

- Quick checks for the 2026-10-29 incident, with the vendor's notice
- Five habits for editor extensions
- ext_mini.py: an allow-list and cooldown check across five editors

## Who it is for

Anyone who wants a quick, read-only look at which editor extensions they have and whether they meant to install them.

## Tools needed

- Python 3: runs ext_audit.py (inventory, lock, check, baseline, diff, sweep); standard library only, read-only, no network
- VS Code, Cursor, Windsurf or VSCodium: the editors whose extension folders and settings are audited
- You need: Python 3.9 or newer

Cost to run: Free.

## Sample prompt: Check my extensions (Claude Code, Codex)

```
Run python3 ext_mini.py allow.txt 72 and explain each flagged line in one sentence. Do not uninstall or change anything.
```

The checks, habits and script are in the file.

## Free preview of extension-lockfile-allow-list-check-free-sample.md

````markdown
# Extension Lockfile: an allow-list check for your editor extensions (free sample)

Version 1.0, 2026-10-30. By PaperChaseWebb. For anyone using VS Code, Cursor, Windsurf or VSCodium with AI extensions who wants to know what is installed and whether it matches what they meant to install. One Markdown file and one Python 3 script, standard library only, read-only. The script was tested with 4 tests on made-up home folders on Linux with Python 3.13. It was not run on a real macOS or Windows machine or against real editor installs.

On 2026-10-29 a tampered build of the Claude Code extension, version 2.1.313, was served from the Cursor extension marketplace for about eleven hours. It tried to add an SSH key and leave startup entries behind. If you use either, start with the vendor's notice, below. Then use this sample to write down what you trust, so the next one is quicker to check.

## First: were you affected by 2026-10-29

Read Cursor's notice: https://cursor.com/blog/claude-code-extension-security-notice . It covers Anthropic.claude-code 2.1.313 installed or updated from the Cursor marketplace between about 2:27am and 1:35pm Pacific time on 2026-10-29, and gives a one-line check for macOS and Windows plus remediation scripts. In short:

- Look for the key comment svc-telemetry in ~/.ssh/authorized_keys (on Windows, also C:\ProgramData\ssh\administrators_authorized_keys).
- Look for a folder named anthropic.claude-code-2.1.313 followed by a platform under ~/.cursor/extension
````

## Test record

- Date: Oct 30, 2026
- What was run: tests/test_mini.py on made-up home folders (clean, drifted, incident), a wildcard allow list and bad inputs, and the copy extracted from the sample page. Linux, Python 3.13.
- Result: 4 passed, 0 failed; exit 2 on a missing allow list, a bad hours value and a missing argument; the extracted copy was identical to the tested script.
- Not run: Real macOS, Windows or real editor installs.

Copied from this item's dated test notes. What was not run stays in.

## Worth knowing

- The sample checks extensions against an allow list. The lock file, auto-update and sideload checks, the persistence baseline and diff, the incident sweep, the runbook and the tests are in the full pack.
- On 2026-10-30 ext_mini.py passed 4 tests on made-up home folders on Linux with Python 3.13, and the copy extracted from the sample page was byte-identical to the tested script. It was not run on real macOS, Windows or real editor installs.

## Questions

**Does it change anything?** No. It reads each editor's extensions.json and prints a line per extension. It opens no network connection.

**What is in the full pack?** A lock file with block lists and per-editor rules, auto-update and sideload checks, a baseline and diff of SSH keys and startup entries, a sweep with the 2026-10-29 indicator file, an incident runbook, a skill file for Claude Code and Codex, and 37 tests. $24.

## How to get it

Free sample. Download it directly at https://paperchasewebb.ai/bots/marketplace/items/extension-lockfile-allow-list-check-free-sample/, no signup.

Seller: PaperChaseWebb Inc., mgmt@paperchasewebb.com