Create a GitHub task list issue which automatically lists issues with a specific tag

I've googled this and read the GH documentation and can't see anything. I'm guessing it can't be done automatically but can probably be done with an action (which I have very limited experience with).

I would like to have an issue which automatically populates a task list with any issues which are tagged with a given label.

You can use the GitHub CLI for this.

To get a list of all issues in a repo that have a specific label, something like this would work:

label='mylabel'
gh issue list --label "$label" --json number --jq 'map("- #\(.number)")[]'

This produces something like

- #232
- #150

which is unfurled into the full issue titles.

To update an issue, you can use

issuenum=100
gh issue edit "$issuenum" --body-file file.md

where file.md contains what you want in the description of the issue.

To use the output of the first command directly, you can use - as the input file:

label='mylabel'
issuenum=100

gh issue list --label "$label" --json number --jq 'map("- #\(.number)")[]' \
    | gh issue edit "$issuenum" --body-file -

And all of this can be done as part of a GitHub Actions workflow. For example, with a manual trigger, expecting the label and the issue to update as inputs:

name: Update issue with task list for label

on:
  workflow_dispatch:
    inputs:
      issue:
        description: Number of the issue to update
        required: true
        type: number
      label:
        description: Label to build list for
        required: true
        type: string

jobs:
  buildlist:
    name: Build task list
    runs-on: ubuntu-20.04
    steps:
      - name: Get issues and update list
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          label: ${{ github.event.inputs.label }}
          issuenum: ${{ github.event.inputs.issue }}
        run: |
          gh issue list --repo "$GITHUB_REPOSITORY --label "$label" \
              --json number --jq 'map("- #\(.number)")[]' \
              | gh issue edit "$issuenum" \
                  --repo "$GITHUB_REPOSITORY" --body-file -