diff --git a/reactor/Core/src/jetbrains/mps/logic/reactor/core/CompositeFeedback.kt b/reactor/Core/src/jetbrains/mps/logic/reactor/core/CompositeFeedback.kt
index bff54cc8..f6d78fcb 100644
--- a/reactor/Core/src/jetbrains/mps/logic/reactor/core/CompositeFeedback.kt
+++ b/reactor/Core/src/jetbrains/mps/logic/reactor/core/CompositeFeedback.kt
@@ -63,6 +63,11 @@ class CompositeFeedback private constructor(private val elements: List<Feedback>
         return composeMessages(elements)
     }
 
+    override fun getDetails(): Any? {
+        // FIXME compose the details
+        return null
+    }
+
     fun elements(): List<Feedback> {
         return elements
     }
diff --git a/reactor/Core/src/jetbrains/mps/logic/reactor/core/DetailedFeedback.kt b/reactor/Core/src/jetbrains/mps/logic/reactor/core/DetailedFeedback.kt
index 59eed93c..cd2ba91c 100644
--- a/reactor/Core/src/jetbrains/mps/logic/reactor/core/DetailedFeedback.kt
+++ b/reactor/Core/src/jetbrains/mps/logic/reactor/core/DetailedFeedback.kt
@@ -27,19 +27,22 @@ import jetbrains.mps.logic.reactor.evaluation.EvaluationFeedback
 open class DetailedFeedback : Feedback {
 
     private val message: String
-    private val severity: EvaluationFeedback.Severity
+    private val severity: Severity
+    private val details: Any?
 
     constructor(message: String) {
         this.message = message
-        this.severity = EvaluationFeedback.Severity.INFO
+        this.severity = Severity.INFO
+        this.details = null
     }
 
-    constructor(message: String, severity: EvaluationFeedback.Severity) {
+    constructor(message: String, severity: Severity, details: Any? = null) {
         this.message = message
         this.severity = severity
+        this.details = details
     }
 
-    override fun getSeverity(): EvaluationFeedback.Severity {
+    override fun getSeverity(): Severity {
         return severity
     }
 
@@ -47,6 +50,10 @@ open class DetailedFeedback : Feedback {
         return message
     }
 
+    override fun getDetails(): Any? {
+        return details
+    }
+
     override fun toString(): String {
         return getSeverity().toString() + " " + message
     }
diff --git a/reactor/Core/src/jetbrains/mps/logic/reactor/core/EvaluationFailure.kt b/reactor/Core/src/jetbrains/mps/logic/reactor/core/EvaluationFailure.kt
index 7dd61839..186c1235 100644
--- a/reactor/Core/src/jetbrains/mps/logic/reactor/core/EvaluationFailure.kt
+++ b/reactor/Core/src/jetbrains/mps/logic/reactor/core/EvaluationFailure.kt
@@ -76,8 +76,12 @@ class EvaluationFailure : Feedback {
         return message
     }
 
+    override fun getDetails(): Any? {
+        return null
+    }
+
     override fun getSeverity(): EvaluationFeedback.Severity {
-        return EvaluationFeedback.Severity.ERROR
+        return EvaluationFeedback.Severity.FAILURE
     }
 
     override fun failureCause(): Throwable? {
diff --git a/reactor/Core/src/jetbrains/mps/logic/reactor/evaluation/EvaluationFeedback.java b/reactor/Core/src/jetbrains/mps/logic/reactor/evaluation/EvaluationFeedback.java
index cc8991ed..8083cd45 100644
--- a/reactor/Core/src/jetbrains/mps/logic/reactor/evaluation/EvaluationFeedback.java
+++ b/reactor/Core/src/jetbrains/mps/logic/reactor/evaluation/EvaluationFeedback.java
@@ -17,7 +17,6 @@
 package jetbrains.mps.logic.reactor.evaluation;
 
 import jetbrains.mps.logic.reactor.core.DetailedFeedback;
-import jetbrains.mps.logic.reactor.program.Rule;
 
 /**
  * Abstract feedback to be provided by the code being evaluated.
@@ -26,36 +25,72 @@ import jetbrains.mps.logic.reactor.program.Rule;
  */
 abstract public class EvaluationFeedback {
 
+    @Deprecated
     public static EvaluationFeedback details(String message) {
-        return new DetailedFeedback(message, Severity.INFO);
+        return new DetailedFeedback(message, Severity.INFO, null);
     }
 
+    @Deprecated
     public static EvaluationFeedback details(String message, Severity severity) {
-        return new DetailedFeedback(message, severity);
+        return new DetailedFeedback(message, severity, null);
+    }
+
+    public static EvaluationFeedback debug(String message, Object details) {
+        return new DetailedFeedback(message, Severity.DEBUG, details);
+    }
+
+    public static EvaluationFeedback debug(String message) {
+        return new DetailedFeedback(message, Severity.DEBUG, null);
+    }
+
+    public static EvaluationFeedback info(String message, Object details) {
+        return new DetailedFeedback(message, Severity.INFO, details);
+    }
+
+    public static EvaluationFeedback info(String message) {
+        return new DetailedFeedback(message, Severity.INFO, null);
+    }
+
+    public static EvaluationFeedback warn(String message, Object details) {
+        return new DetailedFeedback(message, Severity.WARN, details);
+    }
+
+    public static EvaluationFeedback warn(String message) {
+        return new DetailedFeedback(message, Severity.WARN, null);
+    }
+
+    public static EvaluationFeedback error(String message, Object details) {
+        return new DetailedFeedback(message, Severity.ERROR, details);
+    }
+
+    public static EvaluationFeedback error(String message) {
+        return new DetailedFeedback(message, Severity.ERROR, null);
     }
 
     abstract public Severity getSeverity();
 
     abstract public String getMessage();
 
+    abstract public Object getDetails();
+
     public boolean isFailure() {
-        return Severity.ERROR.compareTo(getSeverity()) <= 0;
+        return Severity.FAILURE.compareTo(getSeverity()) <= 0;
     }
 
     public Throwable failureCause() { throw new UnsupportedOperationException(); }
 
-    public static enum Severity {
+    public enum Severity {
 
-        DEBUG(0, "[debug]"),
-        INFO(1, "[info]"),
-        WARN(2, "[warning]"),
-        ERROR(3, "[error]"),
-        FATAL(4, "[fatal]")
+        DEBUG("[debug]"),
+        INFO("[info]"),
+        WARN("[warning]"),
+        ERROR("[error]"),
+        FAILURE("[failure]"),
+        FATAL("[fatal]")
 
         ;
 
-        private Severity(int level, String title) {
-            this.level = level;
+        Severity(String title) {
             this.title = title;
         }
 
@@ -64,8 +99,6 @@ abstract public class EvaluationFeedback {
             return title;
         }
 
-        private final int level;
-
         private final String title;
     }
 }