truly public forum: auto-discover other instances via RNS announce handler

tests/test_sync.py

@@ -378,6 +378,57 @@ def test_sync_peer_discovery():
         shutil.rmtree(dir_c)
 
 
+def test_announce_handler():
+    """Announce handler should auto-discover peers."""
+    dir_a = tempfile.mkdtemp()
+    try:
+        fdb = ForumDB(dir_a)
+        from tinyweb_forum.sync import _ForumAnnounceHandler
+
+        # Mock identity — RNS identity.hash returns bytes
+        class MockIdentity:
+            def __init__(self, h):
+                self._hash_hex = h
+            @property
+            def hash(self):
+                return bytes.fromhex(self._hash_hex)
+
+        local_hex = "aa" * 16
+        peer_hex = "bb" * 16
+
+        handler = _ForumAnnounceHandler(fdb, MockIdentity(local_hex))
+
+        class MockAnnouncedIdentity:
+            def __init__(self, h):
+                self._hash_hex = h
+            @property
+            def hash(self):
+                return bytes.fromhex(self._hash_hex)
+
+        # Announce from a peer
+        handler.received_announce(
+            destination_hash=bytes.fromhex(peer_hex),
+            announced_identity=MockAnnouncedIdentity(peer_hex),
+            app_data=b"tinyweb-forum",
+        )
+
+        known = [r["instance_hash"] for r in fdb.get_synced_instances()]
+        assert peer_hex in known, "peer should be added to sync list"
+
+        # Announce from ourselves should be ignored
+        handler.received_announce(
+            destination_hash=bytes.fromhex(local_hex),
+            announced_identity=MockAnnouncedIdentity(local_hex),
+            app_data=b"tinyweb-forum",
+        )
+
+        known = [r["instance_hash"] for r in fdb.get_synced_instances()]
+        assert known.count(local_hex) == 0, "own announce should be ignored"
+    finally:
+        import shutil
+        shutil.rmtree(dir_a)
+
+
 if __name__ == "__main__":
     test_sync_thread()
     test_sync_reply()
@@ -388,4 +439,5 @@ if __name__ == "__main__":
     test_sync_block_gossip()
     test_sync_updated_content()
     test_sync_peer_discovery()
+    test_announce_handler()
     print("all sync tests passed")