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

Start with the launch.json and tasks.json configurations in the report, then reproduce the flow with pants test --debug-adapter ${file} and the VS Code preLaunchTask. Check the background task's problem matcher and the resulting popup. Done means the preLaunchTask waits as configured and debugpy attaches to the remote configuration.

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