PreLaunchTask correctly waits for background task to wait for client connection, then fails with vague popuop

レポートにある launch.json と tasks.json の設定から始め、pants test --debug-adapter ${file} と VS Code の preLaunchTask を使ってフローを再現します。バックグラウンドタスクの problem matcher と、それによって表示されるポップアップを確認します。preLaunchTask が設定どおりに待機し、debugpy がリモート構成にアタッチすれば完了です。

Environment data

• debugpy version: 1.8.6
• OS and version: MacOS (ARM) 14.6.1
• Python version: 3.10.6
• Using VS Code or Visual Studio: VS Code

Actual behavior

I'm using Pants to run python tests. The program behaves as expected (starts the test with pdb and waits for client connection):

➜  pants test --debug-adapter example_test.py
12:16:25.45 [INFO] Launching debug adapter at '127.0.0.1:5678', which will wait for a client connection...

I would like to use a launch configuration with a preLaunchTask to make debugging easy. However, VS Code does not behave as expected with the background task. I have tried seemingly every possible combination of isBackground, problemMatcher.background, and other fields. Below is what I believe should work according to documentation. When the "Pants: Debug Test" launch configuration is triggered, it calls the correct shell command and correctly waits for the "Launching debug adapter" endPattern to be printed, but then fails with a vague popup

launch.json:

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Pants: Debug Test",
      "preLaunchTask": "Pants Debug Test (Current File)",
      "type": "debugpy",
      "request": "attach",
      "pathMappings": [
        {
          "localRoot": "${workspaceFolder}",
          "remoteRoot": "."
        }
      ],
      "connect": {
        "host": "localhost",
        "port": 5678
      }
    }
  ]
}

tasks.json:

{
  "version": "2.0.0",
  "tasks": [
    {
      "label": "Pants Debug Test (Current File)",
      "type": "shell",
      "command": "pants test --debug-adapter ${file} ",
      "group": "test",
      "presentation": {
        "echo": true,
        "reveal": "always",
        "focus": false,
        "panel": "shared",
        "showReuseMessage": false,
        "clear": true
      },
      "isBackground": true,
      "problemMatcher": {
        "owner": "pants",
        "source": "pytest",
        "fileLocation": "relative",
        "background": {
          "activeOnStart": true,
          "beginsPattern": ".",
          "endsPattern": ".*Launching debug adapter.*",
        },
        "pattern": [
          {
            "regexp": ".",
            "file": 1,
            "location": 2,
            "message": 3
          }
        ]
      }
    }
  ]
}

Expected behavior

PreLaunchTask to run, and debugpy to attach to remote configuraiton

Steps to reproduce:

Above launch.json/task.json and a sample pants project