feat(teams): phase 8 — the notifications bridge, and the gate §7.2 could not check

The same Team event as §6, delivered a third time: push, email, and now a
Discord channel the operator configured. Not a second pipeline — teamNotify.js
already computed the recipient set once, so the bridge is a sink beside the two
that were there.

The design's gate has no data source. §7.2 bridges an event only if "its
visibility is public, or its destination channel is configured for a
members-only Team context". The four team.* streams carry no visibility; forum
threads have no public/members column because a forum is members-only by
construction; and core cannot see a Discord channel's permissions. So §7.2's own
example config names exactly the two events that are never public.

The gate is therefore an attributed operator acknowledgement, in the shape
teams_forum_uploads_ack already uses. It is a precondition — 422, not a quiet
drop at delivery — it is re-asked at delivery as well as at the save, and
changing the channel clears it, because an acknowledgement is about a
destination and cannot survive the destination changing underneath it.

The design's DDL cannot hold its own default row: MariaDB coerces every PRIMARY
KEY column to NOT NULL, so `team_id NULL` — the deployment-wide default every
override overrides — is unrepresentable. Proved on a real MariaDB (error 1048).
Replaced with a surrogate id, a generated team_key AS IFNULL(team_id, 0) in the
unique key, and the foreign key the original had no room for.

One-shot, not queued: "identical to announce and mod-reverse" names two
different reliability models, and a Team notification is the moment it
describes.

Co-Authored-By: Claude <noreply@anthropic.com>

server/src/utils/teamNotify.js

@@ -17,6 +17,14 @@
 // is a destination the recipient chose rather than a relay (§6.4). The asymmetry
 // is the security model, not an inconsistency to tidy up.
 //
+// **Phase 8 added a THIRD sink, and it is a second delivery rather than a second
+// pipeline.** `utils/teamBridge.js` takes the same event, already computed, and
+// hands it to a Discord channel the operator configured — which is why every
+// entry point below calls it beside the tickle instead of anything re-deriving
+// the event. Note that the bridge does NOT take the recipient set: its audience
+// is whoever can read a channel, which is why enabling it for members-only
+// content needs an operator acknowledgement (§7.2, teamIntegration.model.js).
+//
 // **Roster events are push-only, and forum events are the only ones that email.**
 // §6.4's argument for the email sink is the web-only user who never learns that
 // someone replied to their own thread. "Someone joined the guild" is not that: it
@@ -26,6 +34,7 @@
 // the file that says so.
 
 const pushDispatch = require('./pushDispatch')
+const teamBridge = require('./teamBridge')
 const teamNotify = require('../model/teams/teamNotify.model')
 const forumSettings = require('../model/teams/teamForumSettings.model')
 const mailer = require('./mailer')
@@ -119,9 +128,21 @@ async function tickle(streamId, team, { ref, exclude = [] } = {}) {
 // No `memberName` argument, and that is the point: a tickle is content-free, so
 // there is nothing about WHO joined for this function to carry. The name is on
 // the activity feed the app pulls after waking.
-async function memberJoined(team) {
+//
+// `count` is phase 8's one addition and it is for the BRIDGE, not the tickle: a
+// Discord channel has no app on the other end to pull anything, so the message
+// has to say something, and "3 new members joined" is the most a caller that
+// notifies once per sweep can honestly say. Optional, so the sync is the only
+// caller that has to know it exists.
+async function memberJoined(team, { count } = {}) {
   try {
-    return await tickle(STREAMS.MEMBER_JOINED, team, { ref: `team:${team.id}` })
+    const sent = await tickle(STREAMS.MEMBER_JOINED, team, { ref: `team:${team.id}` })
+    await teamBridge.deliver(STREAMS.MEMBER_JOINED, team, {
+      body: teamBridge.memberJoinedBody(count),
+      teamUrl: teamPageUrl(team),
+      url: teamPageUrl(team),
+    })
+    return sent
   } catch (err) {
     log.warn('member-joined notification failed', { teamId: team && team.id, message: err.message })
     return 0
@@ -130,7 +151,13 @@ async function memberJoined(team) {
 
 async function leadershipChanged(team) {
   try {
-    return await tickle(STREAMS.LEADERSHIP_CHANGED, team, { ref: `team:${team.id}` })
+    const sent = await tickle(STREAMS.LEADERSHIP_CHANGED, team, { ref: `team:${team.id}` })
+    await teamBridge.deliver(STREAMS.LEADERSHIP_CHANGED, team, {
+      body: 'Leadership has changed.',
+      teamUrl: teamPageUrl(team),
+      url: teamPageUrl(team),
+    })
+    return sent
   } catch (err) {
     log.warn('leadership notification failed', { teamId: team && team.id, message: err.message })
     return 0
@@ -156,16 +183,26 @@ async function forumPost({ team, threadId, threadTitle, type, authorUserId, auth
     // digest worker has no route in front of it, so the check has to live here as
     // well as there — and a switch flipped between a write and its notification
     // must silence the notification.
-    if (!(await forumSettings.forumsEnabled())) return { push: 0, emails: 0 }
+    if (!(await forumSettings.forumsEnabled())) return { push: 0, emails: 0, bridged: false }
 
     const stream = type === 'announcement' ? STREAMS.ANNOUNCEMENT : STREAMS.FORUM_POST
     const exclude = authorUserId ? [authorUserId] : []
     const push = await tickle(stream, team, { ref: `team:${team.id}:thread:${threadId}`, exclude })
     const emails = await emailImmediate({ team, threadId, threadTitle, type, exclude, authorName, bodyHtml })
-    return { push, emails }
+    // The bridge is NOT given `exclude`. Excluding the author is a property of a
+    // per-recipient sink — nobody wants their own post mailed back to them — and a
+    // channel has no per-recipient anything. Suppressing the message because the
+    // author happens to be in the channel would deprive everyone else in it.
+    const bridged = await teamBridge.deliver(stream, team, {
+      title: threadTitle,
+      body: teamBridge.excerpt(bodyHtml),
+      url: threadUrl(team, threadId),
+      teamUrl: teamPageUrl(team),
+    })
+    return { push, emails, bridged }
   } catch (err) {
     log.warn('forum notification failed', { teamId: team && team.id, message: err.message })
-    return { push: 0, emails: 0 }
+    return { push: 0, emails: 0, bridged: false }
   }
 }