The resolver declares both protocols it answers on

It declared udp/53 only. The daemon listens on tcp/53 as well, and a resolver is
asked over tcp whenever an answer will not fit in a datagram — so on every
converged machine that port is closed while the service reports itself healthy
and the manifest reads as though the resolver were fully declared.

The same fault as issue 136 in miniature: the declaration covers part of what the
service does, and the gap is silent because nothing compares the two.

modules/dnsmasq/module.json

@@ -27,6 +27,13 @@
       "from": "mesh",
       "why": "every name for this machine and what it runs \u2014 the mesh's own answered here, the rest forwarded",
       "fixed": true
+    },
+    {
+      "port": 53,
+      "protocol": "tcp",
+      "from": "mesh",
+      "why": "the same names over tcp, which a resolver answers on as well and is asked for whenever an answer will not fit in a datagram. Declared because the daemon serves it: a declaration that covers one of the two protocols its own service listens on leaves the other closed while everything reports success",
+      "fixed": true
     }
   ],
   "resources": [