diff --git a/lib/db/api.js b/lib/db/api.js
index 81892bdb..25939522 100644
--- a/lib/db/api.js
+++ b/lib/db/api.js
@@ -58,6 +58,7 @@ dbapi.saveDevice = function(serial, device) {
     , provider: device.provider
     , owner: null
     , status: device.status
+    , ready: false
     , statusChangedAt: r.now()
     , createdAt: r.now()
     , lastHeartbeatAt: r.now()
@@ -89,6 +90,7 @@ dbapi.unsetDeviceOwner = function(serial, owner) {
 dbapi.setDeviceAbsent = function(serial) {
   return db.run(r.table('devices').get(serial).update({
     present: false
+  , ready: false
   , lastHeartbeatAt: null
   }))
 }
@@ -101,7 +103,8 @@ dbapi.setDeviceChannel = function(serial, channel) {
 
 dbapi.saveDeviceIdentity = function(serial, identity) {
   return db.run(r.table('devices').get(serial).update({
-    platform: identity.platform
+    ready: true
+  , platform: identity.platform
   , manufacturer: identity.manufacturer
   , operator: identity.operator
   , model: identity.model
diff --git a/lib/roles/app.js b/lib/roles/app.js
index 8dc24053..97fd73c3 100644
--- a/lib/roles/app.js
+++ b/lib/roles/app.js
@@ -139,7 +139,10 @@ module.exports = function(options) {
       .then(function(cursor) {
         return Promise.promisify(cursor.toArray, cursor)()
           .then(function(list) {
-            list.forEach(datautil.applyData)
+            list.forEach(function(device) {
+              datautil.applyData(device)
+              datautil.applyOwner(device, req.user)
+            })
             res.json({
               success: true
             , devices: list
@@ -158,9 +161,11 @@ module.exports = function(options) {
     dbapi.loadDevice(req.params.serial)
       .then(function(device) {
         if (device) {
+          datautil.applyData(device)
+          datautil.applyOwner(device, req.user)
           res.json({
             success: true
-          , device: datautil.applyData(device)
+          , device: device
           })
         }
         else {
@@ -258,22 +263,34 @@ module.exports = function(options) {
         socket.emit('device.remove', {
           serial: message.serial
         , present: false
+        , ready: false
+        , lastHeartbeatAt: null
+        , isOwnedByUser: false
         })
       })
       .on(wire.JoinGroupMessage, function(channel, message) {
-        socket.emit('device.change', message)
+        socket.emit('device.change', datautil.applyOwner({
+            serial: message.serial
+          , owner: message.owner
+          }
+        , user
+        ))
       })
       .on(wire.LeaveGroupMessage, function(channel, message) {
-        socket.emit('device.change', {
-          serial: message.serial
-        , owner: null
-        })
+        socket.emit('device.change', datautil.applyOwner({
+            serial: message.serial
+          , owner: null
+          }
+        , user
+        ))
       })
       .on(wire.DeviceStatusMessage, function(channel, message) {
         socket.emit('device.change', message)
       })
       .on(wire.DeviceIdentityMessage, function(channel, message) {
-        socket.emit('device.change', datautil.applyData(message))
+        datautil.applyData(message)
+        message.ready = true
+        socket.emit('device.change', message)
       })
       .on(wire.TransactionProgressMessage, function(channel, message) {
         socket.emit('tx.progress', channel.toString(), message)
diff --git a/lib/util/datautil.js b/lib/util/datautil.js
index 88229857..10ecb67b 100644
--- a/lib/util/datautil.js
+++ b/lib/util/datautil.js
@@ -50,6 +50,11 @@ module.exports.applyData = function(device) {
   return device
 }
 
+module.exports.applyOwner = function(device, user) {
+  device.isOwnedByUser = !!device.owner && device.owner.email === user.email
+  return device
+}
+
 module.exports.middleware = function() {
   return express.static(pathutil.root('node_modules/stf-devices-db/data/small'))
 }
diff --git a/res/app/components/stf/device/device-service.js b/res/app/components/stf/device/device-service.js
index 811edc12..196634c1 100644
--- a/res/app/components/stf/device/device-service.js
+++ b/res/app/components/stf/device/device-service.js
@@ -17,17 +17,27 @@ module.exports = function DeviceServiceFactory($rootScope, $http, socket) {
       }
     }
 
+    function sync(data) {
+      // usable IF device is physically present AND device is online AND
+      // preparations are ready AND the device has no owner or we are the
+      // owner
+      data.usable = data.present && data.status === 3 && data.ready &&
+        (!data.owner || data.isOwnedByUser)
+    }
+
     function get(data) {
       return devices[devicesBySerial[data.serial]]
     }
 
     function insert(data) {
       devicesBySerial[data.serial] = devices.push(data) - 1
+      sync(data)
       notify()
     }
 
-    function modify(oldData, newData) {
-      _.assign(oldData, newData)
+    function modify(data, newData) {
+      _.assign(data, newData)
+      sync(data)
       notify()
     }
 
diff --git a/res/app/device-list/device-list.jade b/res/app/device-list/device-list.jade
index 365fbee3..8e8e3c69 100644
--- a/res/app/device-list/device-list.jade
+++ b/res/app/device-list/device-list.jade
@@ -91,7 +91,7 @@ div
 
 ul.device-list
   li(ng-repeat='device in tracker.devices track by device.serial')
-    span {{ device.serial }} {{ device.name || device.model }} {{ device.present ? 'present' : 'absent' }} {{ device.owner.email }}
+    span {{ device.serial }} {{ device.name || device.model }} {{ device.present ? 'present' : 'absent' }} {{ device.usable ? 'usable' : 'unusable' }} {{ device.isOwnedByUser ? 'owned by me' : '' }} {{ device.owner.email }}
       a(href='#!/devices/{{ device.serial }}') Linky
     button(ng-click="invite(device)") invite
     button(ng-click="kick(device)") kick