Add Regex Lab Mini App (regex-lab) by Lym308758 · Pull Request #57 · MiniMax-AI/MiniMax-Code-MiniApps

Lym308758 · 2026-10-22T07:20:49Z

Regex Lab · 正则实验室

A live regular-expression workbench that runs inside MiniMax Code. Type a pattern and
some sample text, watch every match appear with its capture groups and named groups,
and preview a replacement — all computed by the Mini App's own Node backend. Nothing
is sent anywhere; the text never leaves the app.

What it does

Live matching against sample text, with match position (index–end), the matched
substring, numbered capture groups, and named capture groups.
Replacement preview using the standard $1, $<name>, $$, $&, $`, $' tokens.
Flag toggles for g / i / m / s / u / y.
Invalid-pattern feedback — a bad regex shows the engine's error instead of failing silently.

Architecture

miniapp/node/regex-engine.mjs — pure regex functions (match / replace), no DOM, shared by
the Node HTTP API and the unit tests.
miniapp/node/server.mjs — Node entry (start(context) -> { dispose }) serving the page and a
small JSON API (/api/match, /api/replace), built on node:http only.
miniapp/client/index.html — dependency-free page (light/dark) that calls the API.

Validation

node scripts/validate.mjs plugins/lym308758/regex-lab → OK (0 errors, 0 warnings);
full-repo node scripts/validate.mjs → repository: OK.
node --test plugins/lym308758/regex-lab/tests/ → 16/16 pass (engine + HTTP handler + lifecycle).
Not verified inside the MiniMax Code host UI: this environment has no MiniMax Code desktop
client, so the page was not opened in the side panel. The Node backend is covered by
tests/server.test.mjs against a real node:http server.

Note

Built with the assistance of an AI coding agent (WorkBuddy).

^{Need help on this PR? Tag @codesmith-bot with what you need.}

A live regular-expression workbench for MiniMax Code: test patterns against sample text, inspect capture groups and named groups, and preview replacements. Computed entirely in the Mini App's Node backend; nothing leaves the machine. Built with the assistance of an AI coding agent (WorkBuddy).

MyPrototypeWhat

Thanks for Regex Lab. It's a tidy, dependency-free plugin, and the scope is right: only plugins/lym308758/regex-lab/ plus one row in each root README. MIT license is included, the manifests match the other plugins, node --test passes (16/16), and npm run validate reports plugins/lym308758/regex-lab: OK. Invalid patterns come back as { ok: false, error } instead of crashing, $<name> / $1 / $$ replacement uses native String.prototype.replace and works ((?<x>a) → [$<x>] gives [a]b), and dispose closes the server and removes the abort listener.

I found two things that need fixing before merge.

Blocking

A catastrophic-backtracking pattern freezes the whole backend (miniapp/node/regex-engine.mjs:22, :42, :68). The user's pattern runs synchronously on the server's event loop with no time limit. runMatch('a'.repeat(32) + '!', '^(a+)+$') never returns: I killed it after 5 seconds. Once that happens, every other request, including GET /dashboard, stalls until the process is killed. Because the UI re-runs on every keystroke, it is easy to trigger by accident while typing a pattern. Suggested fix: run match/replace in a worker_threads Worker and terminate() it after a deadline (for example 1–2 s), returning { ok: false, error: 'timeout' }. Also cap the length of text and pattern.
Zero-length matches with the u flag loop up to the guard (regex-engine.mjs:46). lastIndex += 1 lands in the middle of a surrogate pair. In unicode mode the engine moves it back to the start of the code point, so the same empty match repeats. runMatch('😀', '', 'gu') returns 100001 identical matches at index 0 (about 195 KB of JSON) instead of 2. Advance by code point when regex.unicode || regex.unicodeSets, the way String.prototype.matchAll does. For example: regex.lastIndex = advance(text, regex.lastIndex, regex.unicode || regex.unicodeSets), where advance steps 2 over a surrogate pair. Please add a test for it.

Suggestions

Request body size (server.mjs:79): readJsonBody buffers an unlimited amount. Reject with 413 above a cap (for example 1 MB) and stop reading.
Host/Origin checks: the server accepts requests whatever their Host or Origin header says. Requiring a loopback Host, and a matching Origin on POST, guards against DNS-rebinding and cross-site requests. plugins/1602winxp/pomodoro-sit-timer/miniapp/node/server.mjs (the LOOPBACK_NAMES / isLoopbackAuthority helpers) is a good example to follow.
Guard hit is silent (regex-engine.mjs:47): when MAX_MATCHES is reached, return a truncated: true flag so the UI can say so. A lower cap (for example 10k) would also keep responses small.
Named groups (regex-engine.mjs:85): an unmatched named group becomes '', but unmatched numbered groups become null. Use null for both so the UI can show "（未匹配）" consistently.
Error status: an invalid JSON body returns 400 with the raw SyntaxError message, which is fine. Consider a stable { error: 'invalid_json' }.
README.zh-CN.md row links to plugins/lym308758/regex-lab/. The other rows in the Chinese README link to the plugin's README.zh-CN.md.
Wording: the README row and the description say everything is "computed entirely in the Mini App", but matching actually runs in the plugin's local Node backend. It's still all on the user's machine, so "computed locally" would be more accurate.

MyPrototypeWhat · 2026-10-22T08:56:22Z

+  if (regex.global) {
+    let execResult;
+    let guard = 0;
+    while ((execResult = regex.exec(text)) !== null) {


Blocking: the user's pattern runs synchronously on the server event loop with no time limit. ^(a+)+$ against 'a'.repeat(32)+'!' never returns, and every other request (including /dashboard) hangs with it. Please run this in a worker_threads Worker with a deadline and terminate(), and cap the text and pattern length.

MyPrototypeWhat · 2026-10-22T08:56:22Z

+      matches.push(describeMatch(execResult));
+      // A zero-width match leaves lastIndex unchanged and would loop forever;
+      // nudge it forward so the next search starts after the current position.
+      if (execResult.index === regex.lastIndex) regex.lastIndex += 1;


Blocking: with the u/v flag, += 1 lands inside a surrogate pair and the engine moves it back, so runMatch('😀', '', 'gu') returns 100001 identical matches at index 0. Advance by code point when regex.unicode || regex.unicodeSets.

MyPrototypeWhat · 2026-10-22T08:56:22Z

+      // A zero-width match leaves lastIndex unchanged and would loop forever;
+      // nudge it forward so the next search starts after the current position.
+      if (execResult.index === regex.lastIndex) regex.lastIndex += 1;
+      if (++guard > MAX_MATCHES) break;


Suggestion: tell the caller when this guard trips (for example truncated: true) and consider a lower cap. 100k matches is a very large response.

MyPrototypeWhat · 2026-10-22T08:56:22Z

+  }
+  const namedGroups =
+    m.groups != null
+      ? Object.fromEntries(Object.entries(m.groups).map(([key, value]) => [key, value ?? '']))


Suggestion: unmatched named groups become '' here, but unmatched numbered groups become null. Using null for both would be consistent.

MyPrototypeWhat · 2026-10-22T08:56:22Z

+function readJsonBody(request) {
+  return new Promise((resolve, reject) => {
+    const chunks = [];
+    request.on('data', (chunk) => chunks.push(chunk));


Suggestion: there is no body size limit. Reject with 413 once the total size passes a cap (for example 1 MB) and stop reading.

MyPrototypeWhat · 2026-10-22T08:56:22Z

+        sendHtml(response, 200, html);
+        return;
+      }
+      if (request.method === 'POST' && (route === '/api/match' || route === '/api/replace')) {


Suggestion: check that Host is loopback, and that Origin matches on POST, before routing. See plugins/1602winxp/pomodoro-sit-timer/miniapp/node/server.mjs (isLoopbackAuthority) for an example.

MyPrototypeWhat · 2026-10-22T08:56:22Z

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+| [Regex Lab](plugins/lym308758/regex-lab/) | 实时正则工作台：用样例文本测试正则，逐条查看匹配与捕获组 / 命名组，并预览替换结果；计算全部在 Mini App 内完成，数据不出本机 | [lym308758](https://github.com/lym308758) |


Suggestion: the other rows link to the plugin's README.zh-CN.md. Please use plugins/lym308758/regex-lab/README.zh-CN.md.

MyPrototypeWhat requested changes Oct 22, 2026

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Add Regex Lab Mini App (regex-lab) - #57

Add Regex Lab Mini App (regex-lab)#57
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Lym308758 commented Oct 22, 2026 •

edited by blacksmith-sh Bot

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Regex Lab · 正则实验室

What it does

Architecture

Validation

Note

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Lym308758 commented Oct 22, 2026 •

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