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Backfill all 23 research source notes with terminology extracts, modeling assumptions, conflicts, canonical mappings, and references. Refresh terminology artifacts, refine the conceptual model with explicit scenario paths, reconcile canon surfaces and open questions, and mark the workplan finished.
114 lines
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114 lines
5.0 KiB
Markdown
# ActivityPub Actors and Followers
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## Source Type
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Standard. W3C ActivityPub (REC) with Activity Streams 2.0 vocabulary for
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federated social actors, inboxes, and follower relationships.
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## Domain
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Federated social graphs, actor identity, following/followers, and server-side
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account representation.
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## Why This Source Matters
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ActivityPub treats users as server-side actors with inboxes and outboxes. A
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person may have several actors across servers, mapping well to contextual
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identities and personas.
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## Key Concepts
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- **Actor**: Activity Streams object (Person, Service, Group, Organization,
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Application) with `inbox`, `outbox`, `followers`, `following`, `liked`.
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- **Person actor**: human-associated actor on a federated server.
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- **Service / Application actor**: automated or app-mediated actor.
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- **Group actor**: collective actor with shared inbox/outbox.
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- **Follow activity**: actor A sends Follow to actor B; B may Accept or Reject.
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- **Followers / Following collections**: reverse-indexed social graph edges.
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- **preferredUsername**: handle local to the origin server.
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- **Actor ID (URL)**: globally unique actor URI, typically HTTPS profile URL.
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- **SharedInbox**: delivery optimization for addressing multiple actors.
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- **Public / followers-only addressing**: audience scoping for activities.
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- **WebFinger**: discovery of actor profile from `acct:user@domain`.
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## Relevant Terminology
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| Term | Source meaning |
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| --- | --- |
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| Actor | Server-hosted social entity with inbox/outbox; not necessarily one human. |
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| Person | Actor type for human-associated accounts. |
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| Follow | Directed activity establishing follower relationship. |
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| Follower | Actor who follows another actor. |
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| preferredUsername | Local handle on origin server. |
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| Actor ID | HTTPS URI identifying actor globally. |
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| Inbox / Outbox | Message endpoints for receiving/sending activities. |
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| Group (actor type) | Collective actor in ActivityPub sense. |
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| Service | Non-human automated actor type. |
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| acct: URI | Account identifier for WebFinger discovery. |
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## Modeling Assumptions
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- **Actor is the primary social identity unit**, hosted on an origin server.
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- **One human may operate multiple actors** across servers (implicit, not
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standardized as same-person link).
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- **Following is a social subscription**, not membership or authorization.
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- **Actor ID is globally unique** within the fediverse namespace.
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- **Server is authority** for actor existence and deletion.
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- **Groups and Organizations are actor types**, not separate provisioning models.
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- **No standardized account linking** across actors for same natural person.
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## Identity-Canon Implications
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- ActivityPub **Actor** maps to **Actor** (Person → Natural Person association
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via Account/Profile on origin server).
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- **Person actor** implies **Natural Person** operator but actor ≠ person.
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- **Service/Application actor** maps to **Artificial Agent**.
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- **Group actor** maps to **Community** or **Group** collective actor.
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- **Follow** maps to **Following Relationship** (directed, social).
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- **preferredUsername** + domain maps to **Identifier** in server **Scope**.
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- **Actor ID (URL)** maps to global **Identifier**.
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- Multi-server actors per person support S02, S09, S14 without mandatory
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synonymity.
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- **followers-only** audience maps to Scope/audience boundary on Profile.
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## Terminology Conflicts
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- **Actor vs. User**: ActivityPub actor is server entity; apps say user.
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- **Person vs. Natural Person**: Person is actor type, not verified human.
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- **Group**: ActivityPub Group actor vs. LDAP/SCIM group vs. IAM group.
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- **Follow vs. Member**: following ≠ community membership unless separately defined.
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- **Account vs. Actor**: `acct:` suggests account, but actor is richer object.
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## Candidate Canonical Mappings
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| ActivityPub concept | Candidate canonical concept |
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| --- | --- |
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| Actor (Person) | Actor + Profile + Account (on origin server) |
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| Actor (Service) | Artificial Agent + Service Account |
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| Actor (Group) | Community or Group collective actor |
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| Actor (Organization) | Organization collective actor |
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| Follow activity | Following Relationship |
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| Followers/Following collections | Relationship indexes |
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| preferredUsername | Identifier (local handle) |
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| Actor ID (URL) | Identifier (global) |
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| acct: URI | Identifier |
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| Origin server domain | Scope |
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| Inbox/Outbox | Operational endpoints (downstream) |
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| WebFinger | Discovery protocol (downstream) |
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## Open Questions
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- Should cross-server actors for one Natural Person require explicit Synonymity
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Assertion, or remain unlinked by default?
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- Does ActivityPub Organization actor type map to Organization or Community
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depending on moderation model?
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- How should moved-to / moved-from actor migration (if used) map to Identifier
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Binding supersession?
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- Should followers-only audience be a Profile visibility Scope or separate
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Relationship attribute?
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## References
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- W3C ActivityPub — https://www.w3.org/TR/activitypub/
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- Activity Streams 2.0 — https://www.w3.org/TR/activitystreams-core/
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- WebFinger (RFC 7033) — https://datatracker.ietf.org/doc/html/rfc7033 |