send git-annex tag in initial presence

Will be used for finding other git-annex clients for pairing

Assistant/Threads/PushNotifier.hs

@@ -46,6 +46,7 @@ pushNotifierThread st dstatus pushnotifier = NamedThread thisThread $
 			void $ connectXMPP c $ \jid -> do
 				fulljid <- bindJID jid
 				liftIO $ debug thisThread ["XMPP connected", show fulljid]
+				putStanza $ gitAnnexPresence gitAnnexSignature
 				s <- getSession
 				_ <- liftIO $ forkIO $ void $ runXMPP s $
 					receivenotifications
@@ -62,10 +63,7 @@ pushNotifierThread st dstatus pushnotifier = NamedThread thisThread $
 
 		sendnotifications = forever $ do
 			us <- liftIO $ waitPush pushnotifier
-			let payload = [extendedAway, encodePushNotification us]
-			let notification = (emptyPresence PresenceAvailable)
-				{ presencePayloads = payload }
-			putStanza notification
+			putStanza $ gitAnnexPresence $ encodePushNotification us
 
 		receivenotifications = forever $ do
 			s <- getStanza

Assistant/XMPP.hs

@@ -84,16 +84,23 @@ xmppCredsFile = do
 	dir <- fromRepo gitAnnexCredsDir
 	return $ dir </> "notify-xmpp"
 
-{- Marks the client as extended away. -}
-extendedAway :: Element
-extendedAway = Element (Name (T.pack "show") Nothing Nothing) []
-	[NodeContent $ ContentText $ T.pack "xa"]
+{- A presence with a git-annex tag in it. -}
+gitAnnexPresence :: Element -> Presence
+gitAnnexPresence tag = (emptyPresence PresenceAvailable)
+	{ presencePayloads = [extendedAway, tag] }
+	where
+		extendedAway = Element (Name (T.pack "show") Nothing Nothing) []
+			[NodeContent $ ContentText $ T.pack "xa"]
 
 {- Name of a git-annex tag, in our own XML namespace.
  - (Not using a namespace URL to avoid unnecessary bloat.) -}
 gitAnnexTagName :: Name
 gitAnnexTagName  = Name (T.pack "git-annex") (Just $ T.pack "git-annex") Nothing
 
+{- A git-annex tag, to let other clients know we're a git-annex client too. -}
+gitAnnexSignature :: Element
+gitAnnexSignature = Element gitAnnexTagName [] []
+
 pushAttr :: Name
 pushAttr = Name (T.pack "push") Nothing Nothing
 

doc/design/assistant/xmpp.mdwn

@@ -7,6 +7,7 @@ who share a repository, that is stored in the [[cloud]].
 * Prevent idle disconnection. Probably means sending or receiving pings,
   but would prefer to avoid eg pinging every 60 seconds as some clients do.
 * XMPP pairing
+* git pushes over XMPP (needed for pairing, but also awesome on their own)
 
 ## design goals