on4kst: replace the legacy connection handling with a session-scoped supervisor using bounded connect, login and synchronisation timeouts, heartbeat and stale-link detection, controlled reconnect backoff and session-safe reader/writer queues; validate outgoing protocol context and malformed inbound user frames, enforce one locator per TCP session, publish complete user lists atomically and ignore repeated UE markers, prevent failed initial connections from entering a busy loop, add a compact high-visibility LINK state indicator, and remove false unhandled-frame reports. Solves #71 (#75)

Session-based ON4KST connection lifecycle: Each socket, reader, writer, message bus and queue now belongs to an explicitly identified connection session. Delayed threads from an obsolete connection can therefore no longer process data or close its replacement. ONLINE is reported only after the login has been accepted and all requested user lists have been received. Connection setup, login and synchronisation use bounded timeouts, while heartbeats, missing inbound traffic, EOF and read or write failures trigger controlled reconnect attempts with backoff where appropriate.

Validated ON4KST protocol commands: Outgoing frames are built centrally and checked for valid categories, locators and prohibited frame delimiters. Because ON4KST maintains one locator per TCP session, the main locator is used for both chat categories and a conflicting secondary configuration is logged instead of sending contradictory commands to the server.

pom.xml

@@ -445,6 +445,7 @@
                                 <addmodule>java.sql</addmodule>
                                 <addmodule>java.net.http</addmodule>
                                 <addmodule>jdk.crypto.ec</addmodule>
+                                <addmodule>jdk.net</addmodule>
                             </addmodules>
                             <mainclass>${main.class}</mainclass>
                             <input>${project.build.directory}/modules</input>