WsClient's background thread (ws/client/ws_client.py) called every
on_*_changed handler - and on_ws_connect_changed - directly, but
they all mutate Qt widgets (lcdNumber.display(), setText(),
setChecked(), the plot canvas, ...), which Qt only allows from the
GUI thread. Caught live as "QObject: Cannot create children for a
parent that is in a different thread" on startup, and is a latent
crash/connection-drop risk under load (a cross-thread Qt exception
would be swallowed by ws_client.py's bare except, silently tearing
down the connection).
Adds a generic recv_signal (pyqtSignal(object, object)) carrying the
real handler and its message; _dispatch_recv (its slot) runs on the
GUI thread regardless of which thread emitted, so every handler's
body is now safe. user_message_signal - previously the only handler
already using this pattern, just for one case - becomes redundant
now that on_sud_changed itself always runs on the GUI thread, so its
modal dialog can be shown directly (renamed to show_user_message()).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LhiQe64F74uHV8jzuoSa5K
jensandClaude Sonnet 4.6
7c95a3bde3