Regex Lab

io.github.basitalisandhuv0.1.1更新於 Oct 5, 2026

Test regular expressions in a timeout-guarded worker, explain them, find catastrophic backtracking.

已驗證STDIO僅桌面Developer ToolsSecurity & Monitoring

概覽

AI 產生的概覽

讓助理用樣本測試 JavaScript 正規表達式、逐項解釋模式，並檢查是否有災難性回溯。

功能
提供三個處理 JavaScript（V8）正規表達式的工具。test_regex 以模式和旗標比對最多 50 個樣本字串，回傳每個相符項的位移、文字、編號與具名群組，以及可選的取代預覽。explain_regex 逐項說明字面值、字元類別、跳脫、錨點、群組、環視、量詞和分支，並給出捕獲群組數與旗標含義。check_redos 回報巢狀無界重複、重複下的重疊分支等靜態問題，再用計時探測確認或排除風險。
適用情境
適合在撰寫、除錯或審查正規表達式時使用，需要相符細節、白話解釋或快速排查易導致 ReDoS 的模式。在重視正規表達式正確性與安全性的編輯器或編碼流程中很實用。
執行需求
以 npm 套件形式透過 stdio 在本機執行，通常用 npx 啟動；也發布了 Docker 映像 ghcr.io/basitalisandhu/mcp-regex-lab:0.1.1。npm 方式需要 Node.js。未宣告驗證、環境變數、標頭、網路存取或本機檔案存取。
安裝前請注意
執行在 worker 執行緒中進行，逾時後會被終止，且逾時前完成的樣本仍會回傳，因此結果可能不完整。語法遵循 V8；PCRE、RE2 和 Python 在佔用量詞、後行斷言等處有差異。README 指出，未發現問題和穩定的耗時只是證據，不能證明模式安全。請固定套件版本，以免更新改變實際執行的內容。

安裝

在 SourceWeft 中

  1. 開啟 儀表板中的 Regex Lab，將其新增到工作區。
  2. 為需要使用其工具的對話啟用該服務。

Desktop only，透過 STDIO。 STDIO 服務會啟動本機處理程序，因此需要 SourceWeft 桌面主機。

其他 MCP 客戶端

參照 儲存庫 中的啟動說明。

README

regex-lab MCP server

Tests JavaScript regular expressions against sample strings, explains a pattern construct by construct, and looks for catastrophic backtracking. Every execution runs in a worker thread that is terminated when it exceeds the timeout, so a pathological pattern cannot hang the server.

Part of dev-mcp-servers. Stdio transport only; the server never opens a port.

Tools

ToolInputWhat it returns
test_regexpattern, flags?, samples[] (up to 50 of 20 000 chars), replacement?, timeout_ms? (50 to 10 000, default 2000)Every match per sample with offsets, text, numbered and named groups (with offsets), optional replace preview. Samples finished before a timeout are still returned.
explain_regexpattern, flags?Indented description of literals, classes, escapes, anchors, groups, lookarounds, quantifiers and alternation, plus the capturing group count and flag meanings.
check_redospattern, flags?, probe? (default true), timeout_ms?Static findings (nested unbounded repeats, overlapping alternatives under a repeat, adjacent overlapping repeats) with a probe character each, then timed runs against crafted inputs of growing length to confirm or clear the pattern.

Install

Claude Code:

bash
claude mcp add regex-lab -- npx -y @basitalisandhu/[email protected]

Add -s user to make it available in every project. Any client that reads .mcp.json (Claude Code, Claude Desktop, Cursor):

json
{  "mcpServers": {    "regex-lab": {      "command": "npx",      "args": ["-y", "@basitalisandhu/[email protected]"]    }  }}

Pin the version as shown so that an update to the package cannot change what runs in your editor without you noticing. From a checkout, use "command": "node", "args": ["<path>/packages/regex-lab/dist/index.js"] after npm install && npm run build at the repository root.

What it touches

  • Network: None.
  • Local files: None.
  • Telemetry: none.

Notes

  • Syntax follows V8 (Node.js). PCRE, RE2 and Python differ in places such as possessive quantifiers and lookbehind.
  • g and d flags are added automatically when matching; the replacement preview uses the flags you gave.
  • No findings and flat timings are evidence, not proof, that a pattern is safe.

Build and test

bash
npm install        # at the repository rootnpm run build -w @basitalisandhu/mcp-regex-labnpm test -w @basitalisandhu/mcp-regex-lab

Tests use node:test and the SDK's in-memory transport; they do not reach the network.

Licence

MIT. See LICENSE.

來源：packages/regex-lab/README.md，提交 58c8c95

工具

0
工具後設資料尚未被收錄。

版本歷史

1
  1. v0.1.1最新Oct 5, 2026