feat(cognitive): unlock settled sidechats as SIDECHAT_IDLE and add Main Chat refocus

bin/box-work.py

@@ -746,6 +746,16 @@ def cmd_start(args):
             pass
     s.close()
 
+    # 3b. Refocus agent to Main Chat if resting in a sidechat
+    if acp:
+        try:
+            nav_res = acp.navigate_to_main_chat(agent)
+            if isinstance(nav_res, dict) and nav_res.get("ok") and not nav_res.get("already_main"):
+                print(c_dim(f"✓ Refocused @{agent} session to Main Chat"))
+                time.sleep(1.0)
+        except Exception:
+            pass
+
     # 4. Notify agent via direct chat with Readback requirement
     prompt_msg = (
         f"New build ticket #{issue_num} assigned to you: {title}.\n"