docs: add Contract sections + tag tests to contract items (Tier 2 — 10 files)

lisp/core-communication.lisp

@@ -129,19 +129,20 @@
 (in-suite communication-protocol-suite)
 
 (test test-framing
+  "Contract 1: frame-message produces correct hex length prefix."
   (let* ((msg '(:type :EVENT :payload (:action :handshake)))
          (framed (frame-message msg)))
     (is (string= "00002C" (string-upcase (subseq framed 0 6))))))
 
 (test test-framing-round-trip
-  "A message should survive frame → read-frame without loss."
+  "Contract 3: frame → read-frame preserves message identity."
   (let* ((msg '(:type :EVENT :payload (:action :handshake :version "1.0") :meta (:source :tui)))
          (framed (frame-message msg))
          (unframed (read-framed-message (make-string-input-stream framed))))
     (is (equal msg unframed))))
 
 (test test-framing-empty-message
-  "An empty or simple message should still frame correctly."
+  "Contract 1: simple messages frame with valid hex length."
   (let* ((msg '(:type :ping))
          (framed (frame-message msg)))
     (is (> (length framed) 5))