Always push an option smoke quote for UI init

piker/brokers/data.py

@@ -146,22 +146,29 @@ async def fan_out_to_chans(
     async def request():
         """Get quotes for current symbol subscription set.
         """
-        return await get_quotes(list(symbols2chans.keys()))
+        symbols = list(symbols2chans.keys())
+        if symbols:
+            # subscription can be changed at any time
+            return await get_quotes(symbols)
+        else:
+            return ()
 
     async for quotes in stream_quotes(
         feed.mod, request, rate,
         diff_cached=diff_cached,
     ):
         chan_payloads = {}
+        payload = {}
         for quote in quotes:
             # is this too QT specific?
             symbol = quote['symbol']
+            payload[symbol] = quote
             # set symbol quotes for each subscriber
             for chan, cid in symbols2chans.get(quote['key'], set()):
                 chan_payloads.setdefault(
                     chan,
-                    {'yield': {}, 'cid': cid}
-                )['yield'][symbol] = quote
+                    {'yield': payload, 'cid': cid}
+                )
 
         # deliver to each subscriber (fan out)
         if chan_payloads:
@@ -347,6 +354,12 @@ async def start_quote_stream(
             'option',
             await feed.mod.option_quoter(feed.client, symbols)
         )
+        payload = {
+            quote['symbol']: quote
+            for quote in await get_quotes(symbols)
+        }
+        # push initial smoke quote response for client initialization
+        await chan.send({'yield': payload, 'cid': cid})
     try:
         # update map from each symbol to requesting client's chan
         modify_quote_stream(broker, feed_type, symbols, chan, cid)