Momentum

Momentum is the broadcast pillar of Social Home. Each post — a moment — fans out across paired households and their paired households up to three hops away. Replies are themselves moments, linked to the one they answer so a thread reads as one. The whole pillar lives under Talk → Momentum in the sidebar; the Browse → Moments archive dashboard groups every received moment by day inside the retention window.

What you can post

• Up to 1 000 characters of text (the composer shows a live counter).
• Optionally a single image or a single video clip up to 15 seconds. The composer rejects longer clips before the upload so you don’t waste bandwidth.
• Replies attach to the moment they answer. Threading stays flat — a reply to a reply attaches to the original thread root so the detail view reads top-down without nested branches.

Under the hood

A reply carries parent_moment_id; nested replies are re-parented to the thread root on creation.

Retention

• 24 hours by default for moments from people you don’t follow.
• 7 days for moments from anyone on your follow list.
• The hourly retention scheduler drops every row past the absolute 7-day cap; the visible window is computed per-viewer at list time. You can follow / unfollow from the ⋯ menu on any moment, or from Settings → Privacy → Following.

Federation — the 3-hop relay

            hop=1               hop=2               hop=3
   A ───►   B ───►              C ───►              D
   author    paired household    B's paired household  C's paired household
                                 (skips A)             (skips A and B)

Your household sends the moment to every household it’s paired with. Each of them keeps a copy, shows it to their own members, and passes it on to their paired households — skipping whoever already has it — until it has travelled three hops. A moment that arrives twice by two routes is simply recognised and kept once. Whoever receives it can always check that it really came from the original author, even when it arrived via a friend of a friend.

Under the hood

The author’s household fans the moment to every paired household with hop_count = 1. Each receiving household:

1. Persists the row (UPSERT by moment_id, so duplicate delivery via two relay paths is a no-op).
2. Republishes the bus event so the realtime layer pushes a moment.created WebSocket frame to local viewers.
3. Re-broadcasts the same envelope to its own paired households — bumping hop_count and skipping both the original origin and the immediate sender.
4. Stops when hop_count would exceed MOMENT_MAX_HOPS (3).

The envelope carries an origin_instance_id field that pins the original sender across hops, so the receiving household can verify authority even when the envelope arrived from a relayer rather than the author’s home.

How far you want to look

Three hops is the wire-level cap; you can dial it down per account. Settings → Privacy → Momentum visibility picks between 1 hop (only your paired households), 2 hops (their paired households too), and 3 hops (default — the full relay reach). The setting only changes what you see; your household still relays the full three hops onward so the rest of the mesh stays intact.

Forwarding without storing

When an inbound moment lands and no one in your household can see it — say everyone has dialled max-hops down to 1, or they all block the author — your household skips the local copy entirely and just forwards it to the next hop. Pure pass-through: no disk write, no retention work, no UI surface. The mesh stays whole for everyone else; your household just doesn’t keep a copy of something nobody asked for.

Banned households + open reports

Two extra gates sit on top of the relay:

• Banned households. Admins can ban an entire household; moments from it are dropped on arrival and never relayed onward. Each household keeps its own list — bans don’t federate.
• Open content reports. While a report is open against a moment or its author, your household won’t fan the moment out to others. Resolving or dismissing the report restores the relay. The author still sees their own moment locally — other households only catch up after a moderator acts.

Under the hood

Bans are instance IDs listed under Settings → Federation → Banned instances; matching inbound moments are dropped at the §24.11 pipeline. Reports are content_reports rows; the relay hold lifts once the row is resolved or dismissed via /api/admin/reports.

Going public via a Global Federation Server

Three hops cover paired households, but the wider network goes through the GFS (Global Federation Server) — the relay that helps households find each other. Opt in at Settings → Privacy → Public Momentum, pick a GFS, and your moments fan out to everyone there who follows you. What the GFS knows about you is exactly what you set in Settings → Profile: display name, bio, avatar. Update those and the GFS copy refreshes on save — one identity, no per-pillar overrides.

Discover and follow

• In your Social Home. Talk → Momentum → Discover lists every public author on each GFS you’ve paired with. Search by name, handle, or bio; one click to follow. Their next moment lands in your inbox alongside paired-household moments — flagged with a “via {gfs}” chip.
• From the open web. Each GFS hosts a public landing at /users (the directory) and /users/<id> (per-author page with avatar, bio, follower count, and a deeplink that opens the follow flow on your Social Home). Useful for sharing your Momentum profile with people who aren’t on a Social Home yet.

The directory cards use the same avatar + bio + display name that paired households see — there’s no separate “public persona” to maintain.

Rate limit

One top-level moment per author per 15 minutes. Replies and reactions are exempt — a back-and-forth thread shouldn’t grind to a halt waiting for the timer.

Under the hood

The 15-minute window is enforced at the service layer; the API returns a 429 MOMENT_RATE_LIMIT error code when it kicks in.

Reactions

Pick from a quick row of emoji on the detail page, or tap an existing reaction to set / change yours. Reactions go back to the author’s household only, and the count on their screen updates live.

Under the hood

Reactions ride a unicast back-channel to the author’s household; the update lands as a moment.reaction_changed WebSocket frame in the author’s session.

Block + report

• Block. The same Block action that hides Highlights also hides every moment from that author. Manage blocks at Settings → Privacy → Blocked accounts.
• Report. ⋯ → Report on the detail page files a report in the household admin’s review queue — the same one that handles posts, comments, highlights, and users — so the admin triages everything from one place.

Under the hood

Reports are rows in the unified content_reports queue; admins list them at /api/admin/reports?status=pending.

API

Under the hood

Method	Path	Purpose
GET	/api/moments	List moments visible to the caller (block-aware, follow-aware).
POST	/api/moments	Create a moment. Body: {content, media_url?, media_type?, duration_ms?, parent_moment_id?}.
GET	/api/moments/archive	Full retention-window list for the calendar dashboard.
GET	/api/moments/{id}	Detail with replies + reactions.
DELETE	/api/moments/{id}	Author or admin delete.
PUT / DELETE	/api/moments/{id}/reaction	Set / clear your own emoji.
POST	/api/moments/{id}/report	File a content_reports row.
GET / POST / DELETE	/api/moments/follows[/{user_id}]	Manage your follow list.

The feat_momentum household toggle in Settings → Household features disables every endpoint above with a 403 FEATURE_DISABLED response when admins want to leave the pillar off.