website: add SimpleX Network News channel preview (#7087)

* website: add SimpleX Network News channel preview

* send relay domain/capability to channel owner on profile update

* add channel ID

* add top offset parameter

* allow overscroll

* better scroll

* improve

* fix promoted communities

* use path for channel renderer without host

* fix

---------

Co-authored-by: Evgeny Poberezkin <evgeny@poberezkin.com>

src/Simplex/Chat/Library/Commands.hs

@@ -4918,17 +4918,7 @@ runRelayGroupLinkChecks user = do
                   else void $ withStore' $ \db -> updateRelayOwnStatusFromTo db gInfo RSActive RSInactive
               _ -> pure ()
           _ -> pure ()
-        sendRelayCapIfNeeded cxt gInfo
-    sendRelayCapIfNeeded cxt gInfo = do
-      ChatConfig {webPreviewConfig} <- asks config
-      let currentWebDomain = (\WebPreviewConfig {webDomain} -> webDomain) <$> webPreviewConfig
-      sentWebDomain <- withStore' (`getRelaySentWebDomain` gInfo)
-      when (currentWebDomain /= sentWebDomain) $ do
-        owners <- withStore' $ \db -> getGroupOwners db cxt user gInfo
-        let capableOwners = filter (\m -> memberCurrent m && m `supportsVersion` relayWebCapVersion) owners
-        unless (null capableOwners) $ do
-          void $ sendGroupMessage' user gInfo capableOwners (XGrpRelayCap RelayCapabilities {webDomain = currentWebDomain})
-          withStore' $ \db -> updateRelaySentWebDomain db gInfo currentWebDomain
+        sendRelayCapIfNeeded user gInfo
     checkRelayInactiveGroups = do
       cxt <- chatStoreCxt
       ttl <- asks (relayInactiveTTL . config)

src/Simplex/Chat/Library/Internal.hs

@@ -2126,6 +2126,22 @@ sendGroupMessage' user gInfo members chatMsgEvent =
     ((Right msg) :| [], _) -> pure msg
     _ -> throwChatError $ CEInternalError "sendGroupMessage': expected 1 message"
 
+-- Relay advertises its current web preview capability to channel owners.
+-- Idempotent: sends only when the configured web domain differs from what was last sent, and only to
+-- owners whose recorded chat version supports relayWebCapVersion (older apps can't parse XGrpRelayCap).
+sendRelayCapIfNeeded :: User -> GroupInfo -> CM ()
+sendRelayCapIfNeeded user gInfo = do
+  ChatConfig {webPreviewConfig} <- asks config
+  let currentWebDomain = (\WebPreviewConfig {webDomain} -> webDomain) <$> webPreviewConfig
+  sentWebDomain <- withStore' (`getRelaySentWebDomain` gInfo)
+  when (currentWebDomain /= sentWebDomain) $ do
+    cxt <- chatStoreCxt
+    owners <- withStore' $ \db -> getGroupOwners db cxt user gInfo
+    let capableOwners = filter (\m -> memberCurrent m && m `supportsVersion` relayWebCapVersion) owners
+    unless (null capableOwners) $ do
+      void $ sendGroupMessage' user gInfo capableOwners (XGrpRelayCap RelayCapabilities {webDomain = currentWebDomain})
+      withStore' $ \db -> updateRelaySentWebDomain db gInfo currentWebDomain
+
 sendGroupMessages :: MsgEncodingI e => User -> GroupInfo -> Maybe GroupChatScope -> ShowGroupAsSender -> [GroupMember] -> NonEmpty (ChatMsgEvent e) -> CM (NonEmpty (Either ChatError SndMessage), GroupSndResult)
 sendGroupMessages user gInfo scope asGroup members events = do
   -- TODO [knocking] send current profile to pending member after approval?

src/Simplex/Chat/Library/Subscriber.hs

@@ -3323,6 +3323,8 @@ processAgentMessageConn cxt user@User {userId} corrId agentConnId agentMessage =
               unless (useRelays' g'') $
                 void $ forkIO $ void $ setGroupLinkData' NRMBackground user g''
             Just _ -> updateGroupPrefs_ msgSigned g m $ fromMaybe defaultBusinessGroupPrefs $ groupPreferences p'
+          -- relay advertises its web capability now that the owner's version is known (bumped by saveGroupRcvMsg)
+          when (isRelay (membership g)) $ sendRelayCapIfNeeded user g
           pure $ Just DJSGroup {jobSpec = DJDeliveryJob {includePending = True}}
 
     xGrpPrefs :: GroupInfo -> GroupMember -> GroupPreferences -> RcvMessage -> CM (Maybe DeliveryJobScope)