+Properly handle replying to multiple messages. Currently, the JSON
+reply format only supports a single message, but the default reply
+format accepts searches returning multiple messages. The expected
+behavior of replying to multiple messages is not obvious, and there
+are multiple ideas that might make sense. Some consensus needs to be
+reached on this issue, and then both reply formats should be updated
+to be consistent.
+
+Return docid-based queries in thread search results, instead of
+message-id-based queries. These are much more compact and much faster
+to later query. This will require support from the library, both for
+retrieving docids (probably as an opaque "get a query that identifies
+this message") and for docid queries.
+