diff --git a/common/script/api-v3/preenHistory.js b/common/script/api-v3/preenHistory.js
index 50ffb1518f..64ae4e4715 100644
--- a/common/script/api-v3/preenHistory.js
+++ b/common/script/api-v3/preenHistory.js
@@ -62,7 +62,7 @@ export function preenHistory (history) {
 }
 
 export function preenUserHistory (user, tasksByType, minHistLen = 7) {
-  tasksByType.habits.concat(user.dailys).forEach((task) => {
+  tasksByType.habits.concat(tasksByType.dailys).forEach((task) => {
     if (task.history.length > minHistLen) {
       task.history = preenHistory(user, task.history);
       task.markModified('history');
diff --git a/website/src/controllers/api-v3/tasks.js b/website/src/controllers/api-v3/tasks.js
index ef7180088e..be77c97d70 100644
--- a/website/src/controllers/api-v3/tasks.js
+++ b/website/src/controllers/api-v3/tasks.js
@@ -7,10 +7,12 @@ import {
   NotAuthorized,
   BadRequest,
 } from '../../libs/api-v3/errors';
+import { model as Challenge } from '../../models/challenge';
 import shared from '../../../../common';
 import Q from 'q';
 import _ from 'lodash';
 import scoreTask from '../../../../common/script/api-v3/scoreTask';
+import { preenHistory } from '../../../../common/script/api-v3/preenHistory';
 
 let api = {};
 
@@ -292,7 +294,24 @@ api.scoreTask = {
 
         sendTaskWebhook(user.preferences.webhooks, _generateWebhookTaskData(task, direction, delta, userStats, user));
 
-        // TODO sync challenge
+        // TODO test?
+        if (task.challenge.id && task.challenge.taskId && !task.challenge.broken && task.type !== 'reward') {
+          Tasks.Task.findOne({
+            _id: task.challenge.taskId
+          }).exec()
+          .then(chalTask => {
+            chalTask.value += delta;
+            if (t.type == 'habit' || t.type == 'daily') {
+              chalTask.history.push({value: chalTask.value, date: Number(new Date())});
+              // TODO 1. treat challenges as subscribed users for preening 2. it's expensive to do it at every score - how to have it happen once like for cron?
+              chalTask.history = preenHistory(user, chalTask.history);
+              chalTask.markModified('history');
+            }
+
+            return chalTask.save();
+          });
+          //.catch(next) TODO what to do here
+        }
       });
     })
     .catch(next);
diff --git a/website/src/models/task.js b/website/src/models/task.js
index 74f8d07c53..b31676da10 100644
--- a/website/src/models/task.js
+++ b/website/src/models/task.js
@@ -21,13 +21,13 @@ export let TaskSchema = new Schema({
     type: String,
     validate: [validator.isUUID, 'Invalid uuid.'],
   }],
-  value: {type: Number, default: 0}, // redness or cost for rewards
+  value: {type: Number, default: 0, required: true}, // redness or cost for rewards Required because it must be settable (for rewards)
   priority: {type: Number, default: 1, required: true}, // TODO enum?
   attribute: {type: String, default: 'str', enum: ['str', 'con', 'int', 'per']},
   userId: {type: String, ref: 'User', validate: [validator.isUUID, 'Invalid uuid.']}, // When not set it belongs to a challenge
 
   challenge: {
-    id: {type: String, ref: 'Challenge', validate: [validator.isUUID, 'Invalid uuid.']},
+    id: {type: String, ref: 'Challenge', validate: [validator.isUUID, 'Invalid uuid.']}, // When set (and userId not set) it's the original task
     taskId: {type: String, ref: 'Task', validate: [validator.isUUID, 'Invalid uuid.']}, // When not set but challenge.id defined it's the original task
     broken: {type: String, enum: ['CHALLENGE_DELETED', 'TASK_DELETED', 'UNSUBSCRIBED', 'CHALLENGE_CLOSED']},
     winner: String, // user.profile.name TODO necessary?