From c9ff5a3b62c9942fd4e20c41038ea199a1d84885 Mon Sep 17 00:00:00 2001
From: ugurtafrali <tafraliugur@gmail.com>
Date: Thu, 16 Apr 2026 11:10:56 +0300
Subject: [PATCH 1/2] fix: handle missing/null targeting keys in fractional
 evaluator

---
 core/pkg/evaluator/fractional.go      |  7 +++
 core/pkg/evaluator/fractional_test.go | 61 +++++++++++++++++++++++++++
 2 files changed, 68 insertions(+)

diff --git a/core/pkg/evaluator/fractional.go b/core/pkg/evaluator/fractional.go
index 267151797..11efd915d 100644
--- a/core/pkg/evaluator/fractional.go
+++ b/core/pkg/evaluator/fractional.go
@@ -48,6 +48,10 @@ func (fe *Fractional) Evaluate(values, data any) any {
 		return nil
 	}
 
+	if feDistributions == nil {
+		return nil
+	}
+
 	hashValue := uint32(murmur3.StringSum32(valueToDistribute))
 	return distributeValue(hashValue, feDistributions)
 }
@@ -78,6 +82,9 @@ if len(valuesArray) < 1 {
 			valuesArray = valuesArray[1:]
 		}
 
+		if dataMap[targetingKeyKey] == nil {
+			return "", nil, nil
+		}
 		targetingKey, ok := dataMap[targetingKeyKey].(string)
 		if !ok {
 			return "", nil, fmt.Errorf("flag %q: bucketing value not supplied and no targetingKey in context", flagKey)
diff --git a/core/pkg/evaluator/fractional_test.go b/core/pkg/evaluator/fractional_test.go
index cd92df66f..5bd9cdf43 100644
--- a/core/pkg/evaluator/fractional_test.go
+++ b/core/pkg/evaluator/fractional_test.go
@@ -442,6 +442,67 @@ func TestFractionalEvaluation(t *testing.T) {
 			expectedValue:   blueHex,
 			expectedReason:  model.TargetingMatchReason,
 		},
+		"null targetingKey returns default variant": {
+			flags: []model.Flag{{
+				Key:            "headerColor",
+				State:          "ENABLED",
+				DefaultVariant: redVariant,
+				Variants:       colorVariants,
+				Targeting: []byte(`{
+							"fractional": [
+								["blue", 50],
+								["green", 50]
+							]
+						}`),
+			}},
+			flagKey: "headerColor",
+			context: map[string]any{
+				"targetingKey": nil,
+			},
+			expectedVariant: redVariant,
+			expectedValue:   redHex,
+			expectedReason:  model.DefaultReason,
+		},
+		"missing targetingKey returns default variant": {
+			flags: []model.Flag{{
+				Key:            "headerColor",
+				State:          "ENABLED",
+				DefaultVariant: redVariant,
+				Variants:       colorVariants,
+				Targeting: []byte(`{
+							"fractional": [
+								["blue", 50],
+								["green", 50]
+							]
+						}`),
+			}},
+			flagKey:         "headerColor",
+			context:         map[string]any{},
+			expectedVariant: redVariant,
+			expectedValue:   redHex,
+			expectedReason:  model.DefaultReason,
+		},
+		"empty targetingKey buckets by flagKey": {
+			flags: []model.Flag{{
+				Key:            "headerColor",
+				State:          "ENABLED",
+				DefaultVariant: redVariant,
+				Variants:       colorVariants,
+				Targeting: []byte(`{
+							"fractional": [
+								["blue", 50],
+								["green", 50]
+							]
+						}`),
+			}},
+			flagKey: "headerColor",
+			context: map[string]any{
+				"targetingKey": "",
+			},
+			expectedVariant: greenVariant,
+			expectedValue:   greenHex,
+			expectedReason:  model.TargetingMatchReason,
+		},
 		"single-entry always returns the sole variant": {
 			flags: []model.Flag{{
 				Key:            "headerColor",

From 2f031384c60abc76bd93b6189a8617f346f6278c Mon Sep 17 00:00:00 2001
From: utafrali <tafraliugur@gmail.com>
Date: Thu, 16 Apr 2026 22:04:59 +0300
Subject: [PATCH 2/2] Address review feedback

---
 core/pkg/evaluator/fractional.go      | 4 ++++
 core/pkg/evaluator/fractional_test.go | 8 ++++----
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/core/pkg/evaluator/fractional.go b/core/pkg/evaluator/fractional.go
index 11efd915d..0163e0929 100644
--- a/core/pkg/evaluator/fractional.go
+++ b/core/pkg/evaluator/fractional.go
@@ -90,6 +90,10 @@ if len(valuesArray) < 1 {
 			return "", nil, fmt.Errorf("flag %q: bucketing value not supplied and no targetingKey in context", flagKey)
 		}
 
+		if targetingKey == "" {
+			return "", nil, nil
+		}
+
 		bucketBy = fmt.Sprintf("%s%s", properties.FlagKey, targetingKey)
 	}
 
diff --git a/core/pkg/evaluator/fractional_test.go b/core/pkg/evaluator/fractional_test.go
index 5bd9cdf43..6fcfa7ffb 100644
--- a/core/pkg/evaluator/fractional_test.go
+++ b/core/pkg/evaluator/fractional_test.go
@@ -482,7 +482,7 @@ func TestFractionalEvaluation(t *testing.T) {
 			expectedValue:   redHex,
 			expectedReason:  model.DefaultReason,
 		},
-		"empty targetingKey buckets by flagKey": {
+		"empty targetingKey returns default variant": {
 			flags: []model.Flag{{
 				Key:            "headerColor",
 				State:          "ENABLED",
@@ -499,9 +499,9 @@ func TestFractionalEvaluation(t *testing.T) {
 			context: map[string]any{
 				"targetingKey": "",
 			},
-			expectedVariant: greenVariant,
-			expectedValue:   greenHex,
-			expectedReason:  model.TargetingMatchReason,
+			expectedVariant: redVariant,
+			expectedValue:   redHex,
+			expectedReason:  model.DefaultReason,
 		},
 		"single-entry always returns the sole variant": {
 			flags: []model.Flag{{