tier3: contracts + tests for 12 remaining modules (all 39 files now have Contracts)

org/gateway-tui-model.org

@@ -6,6 +6,16 @@
 The TUI state is a single plist accessed via ~st~ / ~(setf st)~.
 All state mutation flows through event handlers in the controller.
 
+** Contract
+
+1. (init-state): returns a fresh state plist with ~:msgs~ list,
+   ~:input~ buffer, ~:dirty~ flag, and ~:connection~ status.
+2. (add-msg type text): appends a message to the ~:msgs~ list in
+   ~*state*~, tagged with a timestamp and type. Truncates at the
+   message buffer limit.
+3. (queue-event ev): thread-safely enqueues an event for the
+   reader loop. (drain-queue) returns and clears the queue.
+
 ** Package + State
 #+begin_src lisp
 (defpackage :passepartout.gateway-tui