Enforce single assignee on issues

[drewr]

Summary

• Adds reusable workflow enforce-single-assignee.yaml that removes all but the latest-assigned user when an issue has more than one assignee
• Adds documentation in docs/enforce-single-assignee/README.md

Motivation

Ownership of an issue is an important part of working as a team. We can use issue assignments to immediately identify who is taking responsibility:

• 0 assignees: No one. Triage the issue or otherwise archive it.
• 1 assignee: They're the owner. They shepherd the problem through to resolution, turning ambiguity into an outcome.
• 2 or more assignees: Error state. Choose the latest-assigned user. Even a tight team of two or three should have a clear owner who has the responsibility at any given time.

(If an issue needs to be handed off, supply the context in a comment and update the assignee.)

Changes

• .github/workflows/enforce-single-assignee.yaml — reusable workflow_call workflow; triggered on issues: [assigned] by calling repos; uses gh api to DELETE extra assignees, keeping only github.event.assignee
• docs/enforce-single-assignee/README.md — usage, required permissions, behavior table, calling example, troubleshooting

Usage

Calling repos opt in with:

# .github/workflows/enforce-assignees.yaml
on:
  issues:
    types: [assigned]

jobs:
  enforce:
    uses: datum-cloud/actions/.github/workflows/enforce-single-assignee.yaml@v1
    secrets: inherit

Testing

• Created a test issue and assigned 2+ users — workflow ran and removed all but the latest-assigned user
• Assigned 1 user — workflow exited with no action

[ecv]

Yeah this should be a built-in setting honestly.

[drewr]

Not sure how to test without merging first.

[drewr]

Looks like this didn't actually get activated on the assigned action.

[drewr]

Claude activated it for us in 41e9092 and pushed to main before I could intervene.

[scotwells]

@drewr you didn't configure the workflow to execute when issues were assigned in this repo. You only set it up to be called from an external repo.

[scotwells]

Claude activated it for us in 41e9092 and pushed to main before I could intervene.

Looks like there was a bypass rule set for org admins. Adjusted it to still allow, but require to go through a pull request.