Invalid string length

まず、報告されている maxDepth の範囲を使って動作を再現しながら、Step インスタンスを safeSerialize() 経由で追跡し、その後 socket.io-parser の Encoder.encodeAsString まで追跡します。CodeceptUI の I.amOnPage("https://github.com") シナリオを確認し、シリアライズによって Invalid string length が発生しなくなっている一方で、ビジュアルな完了または失敗の出力が引き続き配信されることを確認します。

Using a fresh installation of codeceptjs (v3.7.7) and @codeceptjs/ui (v1.3.8), when running a Hello World test (using both TypeScript and JavaScript, and both plain JS-driven scenario and Gherkin scenario), the UI keeps spinning endlessly, while giving me the following output in the terminal during the first I.amOnPage() statement (using https://github.com for this test purpose):

🌟 CodeceptUI started!
👉 Open http://localhost:3333 to see CodeceptUI in a browser


Unhandled rejection
Unhandled rejection
Application window opened, switch to it to run tests...
HTML Reporter: Starting HTML report generation...
CodeceptJS v3.7.7 #StandWithUkraine
Using test root "/path/to/tests"

Hello World --
    As a Developer
    I want to test Codecept.js with Gherkin
    So I can make sure it will work for subsequent features
Unhandled rejection
Unhandled rejection
  ✖ Login page in 22208ms

-- FAILURES:

  1) Hello World
       Login page:
     
  Invalid string length                                                                                                                                                                             
  RangeError:                                                                                                                                                                                       
      at JSON.stringify (<anonymous>)                                                                                                                                                               
      at Encoder.encodeAsString (node_modules/.pnpm/socket.io-parser@4.2.6/node_modules/socket.io-parser/build/cjs/index.js:93:25)                                                                  
                                                                                                                                                                                                    
                                                                                                                                                                                                    
  ◯ File: file:///path/to/tests/features/hello.feature
  
  ◯ Scenario Steps:
  ✖ I.amOnPage("https://github.com") at ./definitions/steps.ts:12:7
  
  
  ◯ Metadata:
  - browser: chromium
  - browserVersion: 145.0.7632.6
  - windowSize: 1280x720


  FAIL  | 0 passed, 1 failed   // 23s
Run with --verbose flag to see complete NodeJS stacktrace
***************************************
nodeInfo:  24.10.0
osInfo:  macOS 26.3
cpuInfo:  (14) arm64 Apple M4 Pro
chromeInfo:  146.0.7680.153
edgeInfo:  Not Found
firefoxInfo:  Not Found
safariInfo:  26.3
playwrightBrowsers:  "chromium: 145.0.7632.6, firefox: 146.0.1, webkit: 26.0"
If you need more detailed info, just run this: npx codeceptjs info
***************************************
HTML Report saved to: /path/to/tests/output/report.html

The actual code being executed is the following, in any case:

Feature('Hello World');

Scenario('Hello', ({ I }) => {
  I.amOnPage('https://github.com');
  I.see('GitHub');
});

I started the debugger and saw a Step instance being safeSerialize(), leading to the issue. I tried changing the maxDepth default argument value. The following lead to those results:

This was attempted with Node.js 20 and 24.

My best guess is we have some deep copies of certain large objects being serialized, I haven't investigated more into the issue. Happy to help reproduce and debug with whoever wants to give this a shot!