Reject CaseSensitive on predicate types that don't support it

.changes/unreleased/Bugfix-20260713-180016.yaml

@@ -0,0 +1,5 @@
+kind: Bugfix
+body: FilterPredicate.Validate now rejects any CaseSensitive value (true or false) on
+  predicate types that do not support case sensitivity (e.g. exists, matches), since
+  the API ignores the value and returns null for it.
+time: 2026-07-13T18:00:16.000000Z

filters.go

@@ -50,7 +50,10 @@ func (filterPredicate *FilterPredicate) validateCaseSensitivity() error {
 		PredicateTypeEnumDoesNotMatch,
 		PredicateTypeEnumSatisfiesJqExpression,
 	}
-	if slices.Contains(knownNotCaseSensitiveTypes, filterPredicate.Type) && *filterPredicate.CaseSensitive {
+	// The API ignores CaseSensitive for these predicate types and returns null for it
+	// in responses, so any value set here (true or false) would silently disagree with
+	// the API response for clients that round-trip it. Reject any non-nil value.
+	if slices.Contains(knownNotCaseSensitiveTypes, filterPredicate.Type) {
 		return fmt.Errorf("FilterPredicate type '%s' cannot have CaseSensitive value set", filterPredicate.Type)
 	}
 	return nil

filters_test.go

@@ -301,3 +301,66 @@ func TestDeleteFilter(t *testing.T) {
 	// Assert
 	autopilot.Equals(t, nil, err)
 }
+
+func TestFilterPredicateValidateCaseSensitivity(t *testing.T) {
+	boolPtr := func(b bool) *bool { return &b }
+
+	testCases := map[string]struct {
+		predicate ol.FilterPredicate
+		wantErr   bool
+	}{
+		"nil on not-case-sensitive type is valid": {
+			predicate: ol.FilterPredicate{
+				Key:           ol.PredicateKeyEnumRepositoryIDs,
+				Type:          ol.PredicateTypeEnumExists,
+				CaseSensitive: nil,
+			},
+			wantErr: false,
+		},
+		"true on not-case-sensitive type is an error": {
+			predicate: ol.FilterPredicate{
+				Key:           ol.PredicateKeyEnumRepositoryIDs,
+				Type:          ol.PredicateTypeEnumExists,
+				CaseSensitive: boolPtr(true),
+			},
+			wantErr: true,
+		},
+		"false on not-case-sensitive type is an error": {
+			predicate: ol.FilterPredicate{
+				Key:           ol.PredicateKeyEnumRepositoryIDs,
+				Type:          ol.PredicateTypeEnumExists,
+				CaseSensitive: boolPtr(false),
+			},
+			wantErr: true,
+		},
+		"true on case-sensitive type is valid": {
+			predicate: ol.FilterPredicate{
+				Key:           ol.PredicateKeyEnumLanguage,
+				Type:          ol.PredicateTypeEnumEquals,
+				Value:         "Go",
+				CaseSensitive: boolPtr(true),
+			},
+			wantErr: false,
+		},
+		"false on case-sensitive type is valid": {
+			predicate: ol.FilterPredicate{
+				Key:           ol.PredicateKeyEnumLanguage,
+				Type:          ol.PredicateTypeEnumEquals,
+				Value:         "Go",
+				CaseSensitive: boolPtr(false),
+			},
+			wantErr: false,
+		},
+	}
+
+	for name, tc := range testCases {
+		t.Run(name, func(t *testing.T) {
+			err := tc.predicate.Validate()
+			if tc.wantErr {
+				autopilot.Assert(t, err != nil, "expected an error but got nil")
+			} else {
+				autopilot.Equals(t, nil, err)
+			}
+		})
+	}
+}