diff --git a/tests/test_sync.py b/tests/test_sync.py
index 6ad6833..65cb597 100644
--- a/tests/test_sync.py
+++ b/tests/test_sync.py
@@ -429,6 +429,28 @@ def test_announce_handler():
         shutil.rmtree(dir_a)
 
 
+def test_prune_old_content():
+    """Old threads should be pruned after retention period."""
+    dir_a = tempfile.mkdtemp()
+    try:
+        fdb = ForumDB(dir_a)
+        now = "2026-06-05T12:00:00"
+        old = "2026-01-01T12:00:00"
+        fdb.create_thread("new_t", "New", "", "", "", "aaa", "", now)
+        fdb.create_thread("old_t", "Old", "", "", "", "bbb", "", old)
+        fdb.create_post("old_p", "old_t", "", "old reply", "bbb", "", old)
+
+        # Prune with 30 day retention — old thread is ~5 months old
+        fdb.prune_old_content(30)
+
+        assert fdb.get_thread("new_t") is not None, "new thread should survive"
+        assert fdb.get_thread("old_t") is None, "old thread should be pruned"
+        assert len(list(fdb.get_posts("old_t"))) == 0, "old posts should be pruned"
+    finally:
+        import shutil
+        shutil.rmtree(dir_a)
+
+
 if __name__ == "__main__":
     test_sync_thread()
     test_sync_reply()
@@ -440,4 +462,5 @@ if __name__ == "__main__":
     test_sync_updated_content()
     test_sync_peer_discovery()
     test_announce_handler()
+    test_prune_old_content()
     print("all sync tests passed")
diff --git a/tinyweb_forum/db.py b/tinyweb_forum/db.py
index b81c8e7..6ab12de 100644
--- a/tinyweb_forum/db.py
+++ b/tinyweb_forum/db.py
@@ -1,6 +1,7 @@
 import sqlite3
 import os
 import threading
+from datetime import datetime, timedelta
 
 FORUM_DB = "forum.db"
 
@@ -497,3 +498,28 @@ class ForumDB:
             ).fetchall()
         finally:
             self.return_db(db)
+
+    def prune_old_content(self, retention_days):
+        """Delete threads and posts older than retention_days."""
+        db = self.get_db()
+        try:
+            cutoff = (datetime.utcnow() - timedelta(days=retention_days)).strftime("%Y-%m-%dT%H:%M:%S")
+            # Delete posts in old threads
+            db.execute(
+                "DELETE FROM posts WHERE thread_id IN "
+                "(SELECT id FROM threads WHERE updated_at < ?)",
+                (cutoff,),
+            )
+            # Delete orphaned posts (thread already deleted)
+            db.execute(
+                "DELETE FROM posts WHERE thread_id NOT IN (SELECT id FROM threads)"
+            )
+            # Delete old threads
+            db.execute("DELETE FROM threads WHERE updated_at < ?", (cutoff,))
+            # Clean up orphaned upvotes
+            db.execute(
+                "DELETE FROM upvotes WHERE thread_id NOT IN (SELECT id FROM threads)"
+            )
+            db.commit()
+        finally:
+            self.return_db(db)
diff --git a/tinyweb_forum/handlers.py b/tinyweb_forum/handlers.py
index 72c083f..36fdbef 100644
--- a/tinyweb_forum/handlers.py
+++ b/tinyweb_forum/handlers.py
@@ -484,10 +484,28 @@ class ForumHandlers:
             )
         synced_items = f"<ul>{synced_items}</ul>" if synced_items else "<p>No instances synced yet.</p>"
 
+        auto_discover = self.fdb.get_setting("forum_auto_discover", "1")
+        auto_discover_checked = " checked" if auto_discover == "1" else ""
+        retention_days = self.fdb.get_setting("forum_retention_days", "30")
+
         return self._respond(
             f"<h1>forum moderation</h1>"
             f"<p>{msg}</p>"
-            f"<p><em>Forum instances on the mesh are discovered and synced automatically.</em></p>"
+            f"<h2>auto-discovery</h2>"
+            f'<form method="post" action="/forum/auto_discover">'
+            f'{self._csrf_field()}'
+            f'<label><input type="checkbox" name="enabled" value="1"{auto_discover_checked}>'
+            f" automatically discover and sync with other forum instances on the mesh</label><br><br>"
+            f'<button>save</button>'
+            f"</form>"
+            f"<h2>storage</h2>"
+            f'<form method="post" action="/forum/storage">'
+            f'{self._csrf_field()}'
+            f'<label>Keep threads for '
+            f'<input name="retention_days" value="{esc(retention_days)}" size="4"> days</label>'
+            f"<br><small>Older threads are pruned automatically (default: 30). Set to 0 to keep everything.</small><br><br>"
+            f'<button>save</button>'
+            f"</form>"
             f"<h2>blocked instances</h2>"
             f"{blocked_items}"
             f'<form method="post" action="/forum/block">'
@@ -556,6 +574,22 @@ class ForumHandlers:
         self.fdb.set_setting("keyword_filters", keywords)
         return self.handle_moderation("Filters saved.")
 
+    def handle_auto_discover(self, body):
+        enabled = "1" if body.get("enabled") else "0"
+        self.fdb.set_setting("forum_auto_discover", enabled)
+        if self.sync:
+            self.sync.set_auto_discover(enabled == "1")
+        return self.handle_moderation(f"Auto-discovery {'enabled' if enabled == '1' else 'disabled'}.")
+
+    def handle_storage(self, body):
+        days = body.get("retention_days", ["30"])[0].strip()
+        try:
+            days = max(0, int(days))
+        except ValueError:
+            return self.handle_moderation("Invalid retention days.")
+        self.fdb.set_setting("forum_retention_days", str(days))
+        return self.handle_moderation(f"Storage retention set to {days} days.")
+
     def handle_sync_add(self, body):
         instance = body.get("instance", [""])[0].strip().replace("<", "").replace(">", "")
         name = body.get("name", [""])[0].strip()
@@ -726,6 +760,10 @@ class ForumHandlers:
                 return self._with_csrf(self.handle_sync_add(body), csrf_token)
             elif sub == "/unsync":
                 return self._with_csrf(self.handle_unsync(body), csrf_token)
+            elif sub == "/auto_discover":
+                return self._with_csrf(self.handle_auto_discover(body), csrf_token)
+            elif sub == "/storage":
+                return self._with_csrf(self.handle_storage(body), csrf_token)
 
         return self._with_csrf(self._error(404), csrf_token)
 
diff --git a/tinyweb_forum/sync.py b/tinyweb_forum/sync.py
index 098dfc0..440479d 100644
--- a/tinyweb_forum/sync.py
+++ b/tinyweb_forum/sync.py
@@ -50,20 +50,35 @@ class ForumSync:
             allow=RNS.Destination.ALLOW_ALL,
         )
         self.destination.announce(app_data=FORUM_APP.encode("utf-8"))
-        # Auto-discover other forum instances via announces
-        self._announce_handler = _ForumAnnounceHandler(self.fdb, self.identity)
-        RNS.Transport.register_announce_handler(self._announce_handler)
+        if self.fdb.get_setting("forum_auto_discover", "1") == "1":
+            self._enable_announce_handler()
         self._running = True
         self._thread = threading.Thread(target=self._sync_loop, daemon=True)
         self._thread.start()
 
     def stop(self):
         self._running = False
+        self._disable_announce_handler()
+
+    def set_auto_discover(self, enabled):
+        self.fdb.set_setting("forum_auto_discover", "1" if enabled else "0")
+        if enabled:
+            self._enable_announce_handler()
+        else:
+            self._disable_announce_handler()
+
+    def _enable_announce_handler(self):
+        if self._announce_handler is None:
+            self._announce_handler = _ForumAnnounceHandler(self.fdb, self.identity)
+            RNS.Transport.register_announce_handler(self._announce_handler)
+
+    def _disable_announce_handler(self):
         if self._announce_handler:
             try:
                 RNS.Transport.deregister_announce_handler(self._announce_handler)
             except Exception:
                 pass
+            self._announce_handler = None
 
     def _rns_handler(self, path, data, request_id, link_id, remote_identity, requested_at):
         if remote_identity:
@@ -71,6 +86,7 @@ class ForumSync:
         return self.handlers_ref().handle_sync(data)
 
     def _sync_loop(self):
+        prune_counter = 0
         while self._running:
             try:
                 instances = self.fdb.get_synced_instances()
@@ -83,6 +99,14 @@ class ForumSync:
                         print(f"[forum] sync error with {inst['instance_hash'][:16]}: {e}")
             except Exception:
                 pass
+            prune_counter += 1
+            if prune_counter >= 6:
+                prune_counter = 0
+                try:
+                    days = int(self.fdb.get_setting("forum_retention_days", "30"))
+                    self.fdb.prune_old_content(days)
+                except Exception:
+                    pass
             for _ in range(SYNC_INTERVAL):
                 if not self._running:
                     return