feat: download profile images locally in processProfileUpdateEvent

When a profile_update relay arrives with avatar/banner URLs, download
the files to local storage instead of storing remote absolute URLs.
Falls back to absolute URL on any download failure. Cleans up old
local files when replaced.

packages/server/src/routes/federation.ts

@@ -845,7 +845,7 @@ export async function federationRoutes(app: FastifyInstance): Promise<void> {
       }
 
       // 3. Process each event
-      const { accepted, rejected } = processRelayEvents(body.events, sourceInstance, peer.origin, db);
+      const { accepted, rejected } = await processRelayEvents(body.events, sourceInstance, peer.origin, db);
 
       // 4. Update peer status
       db.update(schema.federationPeers)
@@ -1270,12 +1270,12 @@ export async function federationRoutes(app: FastifyInstance): Promise<void> {
  * Process an array of federation relay events. Used by the HTTP relay endpoint
  * and directly by the initial-sync worker (which skips the HTTP round-trip).
  */
-export function processRelayEvents(
+export async function processRelayEvents(
   events: FederationRelayEvent[],
   sourceInstance: string,
   peerOrigin: string,
   db: ReturnType<typeof getDb>,
-): { accepted: string[]; rejected: Array<{ messageId: string; reason: string }> } {
+): Promise<{ accepted: string[]; rejected: Array<{ messageId: string; reason: string }> }> {
   const accepted: string[] = [];
   const rejected: Array<{ messageId: string; reason: string }> = [];
 
@@ -1343,7 +1343,7 @@ export function processRelayEvents(
           processDmTypingStopEvent(event, sourceInstance, db, accepted, rejected);
           break;
         case 'profile_update':
-          processProfileUpdateEvent(event, sourceInstance, db, accepted, rejected);
+          await processProfileUpdateEvent(event, sourceInstance, db, accepted, rejected);
           break;
         case 'read_state_update':
           processReadStateUpdateEvent(event, sourceInstance, db, accepted, rejected);
@@ -3922,13 +3922,13 @@ async function downloadProfileAsset(
   }
 }
 
-function processProfileUpdateEvent(
+async function processProfileUpdateEvent(
   event: FederationRelayEvent,
   sourceInstance: string,
   db: ReturnType<typeof getDb>,
   accepted: string[],
   rejected: Array<{ messageId: string; reason: string }>,
-): void {
+): Promise<void> {
   const payload = event.profileUpdate;
   if (!payload) {
     rejected.push({ messageId: event.messageId, reason: 'missing_profile_update_payload' });
@@ -3977,12 +3977,49 @@ function processProfileUpdateEvent(
     return;
   }
 
+  // ── Resolve avatar/banner: download locally, fall back to absolute URL ──
+  let resolvedAvatar: string | null = payload.avatar ?? null;
+  let resolvedBanner: string | null = payload.banner ?? null;
+
+  // Download avatar
+  if (resolvedAvatar && resolvedAvatar.startsWith('http')) {
+    const localFile = await downloadProfileAsset(resolvedAvatar, sourceInstance);
+    resolvedAvatar = localFile ?? resolvedAvatar; // local filename or absolute URL fallback
+  } else if (resolvedAvatar && !resolvedAvatar.startsWith('http')) {
+    // Bare filename (shouldn't happen) — resolve to absolute URL
+    const baseUrl = sourceInstance.startsWith('http') ? sourceInstance : `https://${sourceInstance}`;
+    const absoluteUrl = `${baseUrl}/api/uploads/${resolvedAvatar}`;
+    const localFile = await downloadProfileAsset(absoluteUrl, sourceInstance);
+    resolvedAvatar = localFile ?? absoluteUrl;
+  }
+
+  // Download banner
+  if (resolvedBanner && resolvedBanner.startsWith('http')) {
+    const localFile = await downloadProfileAsset(resolvedBanner, sourceInstance);
+    resolvedBanner = localFile ?? resolvedBanner;
+  } else if (resolvedBanner && !resolvedBanner.startsWith('http')) {
+    const baseUrl = sourceInstance.startsWith('http') ? sourceInstance : `https://${sourceInstance}`;
+    const absoluteUrl = `${baseUrl}/api/uploads/${resolvedBanner}`;
+    const localFile = await downloadProfileAsset(absoluteUrl, sourceInstance);
+    resolvedBanner = localFile ?? absoluteUrl;
+  }
+
+  // Clean up old local files being replaced
+  const oldAvatar = localUser.avatar;
+  const oldBanner = localUser.banner;
+  if (oldAvatar && !oldAvatar.startsWith('http') && oldAvatar !== resolvedAvatar) {
+    deleteUploadFile(oldAvatar);
+  }
+  if (oldBanner && !oldBanner.startsWith('http') && oldBanner !== resolvedBanner) {
+    deleteUploadFile(oldBanner);
+  }
+
   // Authoritative overwrite — home instance is always right
   db.update(schema.users)
     .set({
       displayName: payload.displayName,
-      avatar: payload.avatar,
-      banner: payload.banner,
+      avatar: resolvedAvatar,
+      banner: resolvedBanner,
       accentColor: payload.accentColor,
       avatarColor: payload.avatarColor,
       bio: payload.bio,