From 62a16e884a03eb9573cfc17182d487ceefc00c7c Mon Sep 17 00:00:00 2001
From: Jannis Braun <151788261+TheZwiss@users.noreply.github.com>
Date: Thu, 26 Mar 2026 20:28:19 +0100
Subject: [PATCH] feat(federation): extend catch-up sync to include group DMs
 and membership mutations

---
 packages/server/src/routes/federation.ts | 42 ++++++++++++++++++++----
 1 file changed, 35 insertions(+), 7 deletions(-)

diff --git a/packages/server/src/routes/federation.ts b/packages/server/src/routes/federation.ts
index 62e7c567..951f2552 100644
--- a/packages/server/src/routes/federation.ts
+++ b/packages/server/src/routes/federation.ts
@@ -529,6 +529,7 @@ export async function federationRoutes(app: FastifyInstance): Promise<void> {
 
       const sinceTimestamp = body.sinceTimestamp;
       const dmChannelIdFilter = body.dmChannelId && typeof body.dmChannelId === 'string' ? body.dmChannelId : null;
+      const federatedIdFilter = body.federatedId && typeof body.federatedId === 'string' ? body.federatedId : null;
 
       // Clamp limit: min 1, max 500, default 100
       let limit = typeof body.limit === 'number' ? body.limit : 100;
@@ -545,6 +546,17 @@ export async function federationRoutes(app: FastifyInstance): Promise<void> {
 
       const sharedChannelIds = sharedChannelRows.map(r => r.dm_channel_id);
 
+      // If filtering by federatedId, resolve to local channel ID
+      let effectiveChannelFilter = dmChannelIdFilter;
+      if (federatedIdFilter && !effectiveChannelFilter) {
+        const fedChannel = rawDb.prepare(`
+          SELECT id FROM dm_channels WHERE federated_id = ?
+        `).get(federatedIdFilter) as { id: string } | undefined;
+        if (fedChannel) {
+          effectiveChannelFilter = fedChannel.id;
+        }
+      }
+
       if (sharedChannelIds.length === 0) {
         const syncResponse: FederationSyncResponse = {
           events: [],
@@ -567,9 +579,9 @@ export async function federationRoutes(app: FastifyInstance): Promise<void> {
         payload: string | null;
       }>;
 
-      if (dmChannelIdFilter) {
+      if (effectiveChannelFilter) {
         // Validate that the requested channel is actually shared with this peer
-        if (!sharedChannelIds.includes(dmChannelIdFilter)) {
+        if (!sharedChannelIds.includes(effectiveChannelFilter)) {
           const syncResponse: FederationSyncResponse = {
             events: [],
             hasMore: false,
@@ -581,12 +593,13 @@ export async function federationRoutes(app: FastifyInstance): Promise<void> {
         mutationRows = rawDb.prepare(`
           SELECT ml.id, ml.dm_message_id, ml.dm_channel_id, ml.mutation_type, ml.mutated_at, ml.payload
           FROM federation_mutation_log ml
-          JOIN dm_messages dm ON ml.dm_message_id = dm.id
+          LEFT JOIN dm_messages dm ON ml.dm_message_id = dm.id
           WHERE ml.dm_channel_id = ?
             AND ml.mutated_at > ?
+            AND (dm.id IS NOT NULL OR ml.mutation_type IN ('delete', 'member_add', 'member_remove', 'ownership_transfer'))
           ORDER BY ml.mutated_at ASC
           LIMIT ?
-        `).all(dmChannelIdFilter, sinceTimestamp, limit) as typeof mutationRows;
+        `).all(effectiveChannelFilter, sinceTimestamp, limit) as typeof mutationRows;
 
         // For delete mutations, the dm_messages row won't exist — handle separately
         const deleteMutations = rawDb.prepare(`
@@ -598,7 +611,7 @@ export async function federationRoutes(app: FastifyInstance): Promise<void> {
             AND ml.dm_message_id NOT IN (SELECT dm.id FROM dm_messages dm WHERE dm.id = ml.dm_message_id)
           ORDER BY ml.mutated_at ASC
           LIMIT ?
-        `).all(dmChannelIdFilter, sinceTimestamp, limit) as typeof mutationRows;
+        `).all(effectiveChannelFilter, sinceTimestamp, limit) as typeof mutationRows;
 
         // Merge, deduplicate, sort, and re-limit
         const seen = new Set(mutationRows.map(r => r.id));
@@ -619,9 +632,10 @@ export async function federationRoutes(app: FastifyInstance): Promise<void> {
         mutationRows = rawDb.prepare(`
           SELECT ml.id, ml.dm_message_id, ml.dm_channel_id, ml.mutation_type, ml.mutated_at, ml.payload
           FROM federation_mutation_log ml
-          JOIN dm_messages dm ON ml.dm_message_id = dm.id
+          LEFT JOIN dm_messages dm ON ml.dm_message_id = dm.id
           WHERE ml.dm_channel_id IN (${placeholders})
             AND ml.mutated_at > ?
+            AND (dm.id IS NOT NULL OR ml.mutation_type IN ('delete', 'member_add', 'member_remove', 'ownership_transfer'))
           ORDER BY ml.mutated_at ASC
           LIMIT ?
         `).all(...sharedChannelIds, sinceTimestamp, limit) as typeof mutationRows;
@@ -656,7 +670,21 @@ export async function federationRoutes(app: FastifyInstance): Promise<void> {
       const events: FederationRelayEvent[] = [];
 
       for (const mutation of mutationRows) {
-        const mutationType = mutation.mutation_type as 'create' | 'update' | 'delete' | 'reaction_add' | 'reaction_remove';
+        const mutationType = mutation.mutation_type as 'create' | 'update' | 'delete' | 'reaction_add' | 'reaction_remove' | 'member_add' | 'member_remove' | 'ownership_transfer';
+
+        if (['member_add', 'member_remove', 'ownership_transfer'].includes(mutationType)) {
+          // Membership mutations store the full event in the payload
+          const payload = mutation.payload ? JSON.parse(mutation.payload) : {};
+          events.push({
+            eventType: mutationType as FederationRelayEvent['eventType'],
+            dmChannelId: mutation.dm_channel_id,
+            messageId: mutation.dm_message_id,
+            encryptionVersion: 0,
+            timestamp: mutation.mutated_at,
+            ...payload,
+          });
+          continue;
+        }
 
         if (mutationType === 'delete') {
           // For deletes, we don't need the message content — just the ID and channel