Implement federated moderation for ActivityPub
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## Goal
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Clearly outline the goal of the issue and why we are doing it
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To allow Minds to become aware of bad content on the Fediverse, and for Minds to notify other sites about content we have reported, we should implement the Flag activity type
## What needs to be done
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Clearly detail what needs to be done to achieve the goal set out above
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See https://docs.joinmastodon.org/spec/activitypub/#Flag
### Example payload (from mastodon)
```json
{
"@context": "https://www.w3.org/ns/activitystreams",
"id": "http://mastodon.local/982b445b-9876-4591-94dc-a7a2542de91c",
"type": "Flag",
"actor": "http://mastodon.local/actor",
"content": "",
"object": [
"http://d560-129-213-177-45.ngrok-free.app/api/activitypub/users/1521521911551496210"
]
}
```
## QA
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Consideration is given to how the issue will be demoed and tested prior to being deployed
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## UX/Design
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Sufficient wireframes have been presented and understood by the development team. Full mockups are not required and re-usable components are encouraged.
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## Mobile
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Does a mobile card need to be created? Any notes for mobile?
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- [ ] Is Mobile Required?
## Personas
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Who does this user impact and why (optional)
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## Experiments
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Experiments are not required, but it should be made clear if one is expected. If experiments are required, the hypothesis should be outlined.
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## Acceptance Criteria
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Everyone should be able to understand what is expected to be delivered
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- [ ] When a Minds post is reported (and upheld by an admin), we should create a 'Flag' event and propagate out to all domains
- [ ] Minds should process Flag activity and generate reports if the entity exists
## Definition of Ready Checklist
- [ ] Definition Of Done (DoD)
- [ ] Acceptance criteria
- [ ] Weighted
- [ ] QA
- [ ] UX/Design
- [ ] Personas
- [ ] Experiments
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