Replies to a persona's posts reach its followers; personas join remote events

Two owner decisions of 2026-10-05, recorded in the roadmap.

Replies passed on ("the fediverse is broken without"): a public or unlisted
reply from another server to a persona's public, unlisted or followers-only
post goes on to the persona's followers as its author's server sent it, as
Mastodon forwards it, never to the replier's own server, never for a
local-only or group post; its edit and deletion follow. Only an activity its
own actor delivered is passed on (Arrival.Raw), so nothing forwarded is
forwarded again. The town checks it as relay.reply cells (specs/relay-five:
882 checks pass); Mastodon takes a passed-on activity only with an LD
signature, which GoToSocial and Akkoma don't add, and the checker knows it.

Events: a persona joins another server's event with a Join and leaves it with
a Leave, both to the organiser only, through
POST /api/privapub/v1/statuses/:id/join|leave; the organiser's Accept or
Reject is routed by our join id and shows as privapub.event.participation.
Events by invitation or taken on another site are refused before anything
is sent. Mobilizon's scenario joins and leaves an event (28 checks) and keeps
one for decePubClient's e2e.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw

docs/ROADMAP.md

@@ -67,6 +67,8 @@ Written 2026-10-01 from the original 2023 code, the decePubClient UI, a federati
     RFC 9421 signatures verified; forwarded activities taken as their origin vouches; an id a sender reuses is no copy;
     a follow sent again under a new id (Lemmy); a group's event its organiser edits; NodeInfo read as Mobilizon and
     Funkwhale serve it; Funkwhale's answers named after our follow and its deletions of several uploads.
+  - GoToSocial's interaction policies both ways; personas join and leave remote events; third-party replies to a
+    persona's posts passed on to its followers (owner decisions 2026-10-05).
 - [ ] P7 Threads, communities, moderation, the social graph
 - [ ] P8 Signatures, discovery, the long tail
 - [x] P9 Reading at volume (owner decision 2026-10-04, back from "Cut"): lists, server-side filters, scheduled posts,
@@ -254,6 +256,13 @@ and circles (see Owner decisions).
 | How work lands | Commits on master in both repositories; nothing is pushed, tagged or deployed without asking. |
 | Still asked first | Anything new that tells another server something about a persona, Web Push (traffic to push services), any admin endpoint in production, and anything acting from production or the owner's accounts. |
 
+### Owner decisions on events and threads (2026-10-05)
+
+| Question | Decision |
+|---|---|
+| May a persona join a remote event? | **Yes.** A persona joins and leaves another server's event (`Join`/`Leave`, sent to the event's organiser only). Its participation is public on that server, as on every platform with events. Events that take participants only by invitation or on another site are refused before anything is sent. |
+| Should PrivaPub pass on replies to a persona's posts? | **Yes, "the fediverse is broken without".** A public or unlisted reply that someone on another server writes to a persona's post goes on to the persona's followers, as Mastodon forwards it: the activity as its author signed it, never to the replier's own server, never for a post that is local-only, in a group or not shown to followers. Its edits and deletion follow the same way. |
+
 ## Libraries (researched; no maintained .NET ActivityPub library exists, so Letterbook and Iceshrimp.NET both wrote their own)
 
 | Area | Choice |
@@ -640,7 +649,8 @@ it, raw where it doesn't.
   - `indexable`/`discoverable`/`searchableBy`;
   - edit history from `formerRepresentations`;
   - PeerTube reply rules and `ApproveReply`.
-- **Events:** structured RSVP (`Join`/`Leave` with stable ids).
+- **Events:** structured RSVP (`Join`/`Leave` with stable ids): **done 2026-10-05** (owner decision above), checked live
+  against Mobilizon.
 
 #### P8 Signatures, discovery and the long tail
 - **Signatures:**