diff --git a/client_ideas.md b/client_ideas.md
new file mode 100644
index 0000000..5cb24c1
--- /dev/null
+++ b/client_ideas.md
@@ -0,0 +1,8 @@
+- morse sound + microfoon
+- qr code -> 1 camera en een scherm
+- file upload via tfp + file watcher
+- ?? excel file ??
+- simple http request or netcat
+- licht sensor
+- andere sensors (vochtigheid, ...)
+
diff --git a/watcher/app.py b/watcher/app.py
index 5039683..27ee5d9 100644
--- a/watcher/app.py
+++ b/watcher/app.py
@@ -35,8 +35,12 @@ def link_start(run, index):
     if db["current_run"] != run:
         return "Wrong run number, you are probably behind.", 404
     else:
-        db["run_data"][run]["data"][index]["start"] = datetime.datetime.now()
-        return "Success."
+        link_data = db["run_data"][run]["data"][index]
+        if link_data["start"]:
+            return "you already started in this run. Ignoring this request."
+        else:
+            link_data["start"] = datetime.datetime.now()
+            return "Success."
 
 
 @app.route("/link/handoff/<run>/<index>")
@@ -44,8 +48,12 @@ def link_handoff(run, index):
     if db["current_run"] != run:
         return "Wrong run number, you are probably behind.", 404
     else:
-        db["run_data"][run]["data"][index]["handoff"] = datetime.datetime.now()
-        return "Success."
+        link_data = db["run_data"][run]["data"][index]
+        if link_data["handoff"]:
+            return "you already handed off control during this run. Ignoring this request"
+        else:
+            link_data["handoff"] = datetime.datetime.now()
+            return "Success."
 
 
 if __name__ == '__main__':
diff --git a/watcher/static/index.js b/watcher/static/index.js
new file mode 100644
index 0000000..1999b8b
--- /dev/null
+++ b/watcher/static/index.js
@@ -0,0 +1,3 @@
+const io = require('socket.io-client');
+// or with import syntax
+import io from 'socket.io-client';