Add a specific issue type for fragment cycles

libraries/apollo-ast/api/apollo-ast.api

@@ -132,6 +132,12 @@ public final class com/apollographql/apollo/ast/ForeignSchema {
 	public final fun getVersion ()Ljava/lang/String;
 }
 
+public final class com/apollographql/apollo/ast/FragmentCycle : com/apollographql/apollo/ast/GraphQLValidationIssue {
+	public fun <init> (Ljava/lang/String;Lcom/apollographql/apollo/ast/SourceLocation;)V
+	public fun getMessage ()Ljava/lang/String;
+	public fun getSourceLocation ()Lcom/apollographql/apollo/ast/SourceLocation;
+}
+
 public final class com/apollographql/apollo/ast/GQLArgument : com/apollographql/apollo/ast/GQLNamed, com/apollographql/apollo/ast/GQLNode {
 	public fun <init> (Lcom/apollographql/apollo/ast/SourceLocation;Ljava/lang/String;Lcom/apollographql/apollo/ast/GQLValue;)V
 	public synthetic fun <init> (Lcom/apollographql/apollo/ast/SourceLocation;Ljava/lang/String;Lcom/apollographql/apollo/ast/GQLValue;ILkotlin/jvm/internal/DefaultConstructorMarker;)V

libraries/apollo-ast/api/apollo-ast.klib.api

@@ -238,6 +238,15 @@ final class com.apollographql.apollo.ast/ForeignSchema { // com.apollographql.ap
         final fun <get-version>(): kotlin/String // com.apollographql.apollo.ast/ForeignSchema.version.<get-version>|<get-version>(){}[0]
 }
 
+final class com.apollographql.apollo.ast/FragmentCycle : com.apollographql.apollo.ast/GraphQLValidationIssue { // com.apollographql.apollo.ast/FragmentCycle|null[0]
+    constructor <init>(kotlin/String, com.apollographql.apollo.ast/SourceLocation?) // com.apollographql.apollo.ast/FragmentCycle.<init>|<init>(kotlin.String;com.apollographql.apollo.ast.SourceLocation?){}[0]
+
+    final val message // com.apollographql.apollo.ast/FragmentCycle.message|{}message[0]
+        final fun <get-message>(): kotlin/String // com.apollographql.apollo.ast/FragmentCycle.message.<get-message>|<get-message>(){}[0]
+    final val sourceLocation // com.apollographql.apollo.ast/FragmentCycle.sourceLocation|{}sourceLocation[0]
+        final fun <get-sourceLocation>(): com.apollographql.apollo.ast/SourceLocation? // com.apollographql.apollo.ast/FragmentCycle.sourceLocation.<get-sourceLocation>|<get-sourceLocation>(){}[0]
+}
+
 final class com.apollographql.apollo.ast/GQLArgument : com.apollographql.apollo.ast/GQLNamed, com.apollographql.apollo.ast/GQLNode { // com.apollographql.apollo.ast/GQLArgument|null[0]
     constructor <init>(com.apollographql.apollo.ast/SourceLocation? = ..., kotlin/String, com.apollographql.apollo.ast/GQLValue) // com.apollographql.apollo.ast/GQLArgument.<init>|<init>(com.apollographql.apollo.ast.SourceLocation?;kotlin.String;com.apollographql.apollo.ast.GQLValue){}[0]
 

libraries/apollo-ast/src/commonMain/kotlin/com/apollographql/apollo/ast/Issue.kt

@@ -70,6 +70,13 @@ class DifferentShape(override val message: String, override val sourceLocation:
 
 class UnusedFragment(override val message: String, override val sourceLocation: SourceLocation?) : GraphQLValidationIssue
 
+/**
+ * There is a fragment cycle.
+ *
+ * See https://spec.graphql.org/September2025/#sec-Fragment-Spreads-Must-Not-Form-Cycles
+ */
+class FragmentCycle(override val message: String, override val sourceLocation: SourceLocation?) : GraphQLValidationIssue
+
 /**
  * Two type definitions have the same name
  */

libraries/apollo-ast/src/commonMain/kotlin/com/apollographql/apollo/ast/internal/ExecutableValidationScope.kt

@@ -6,6 +6,7 @@ import com.apollographql.apollo.ast.Catch
 import com.apollographql.apollo.ast.DeprecatedUsage
 import com.apollographql.apollo.ast.DifferentShape
 import com.apollographql.apollo.ast.ExecutableValidationResult
+import com.apollographql.apollo.ast.FragmentCycle
 import com.apollographql.apollo.ast.GQLArgument
 import com.apollographql.apollo.ast.GQLBooleanValue
 import com.apollographql.apollo.ast.GQLDirective
@@ -117,7 +118,7 @@ internal class ExecutableValidationScope(
             val index = path.indexOf("__${name}")
             val nextPath = path + "__${fragment.name}"
             if (index != -1) {
-              registerIssue("Fragment '$name' spreads itself, creating a cycle at '${nextPath.subList(index, nextPath.size).joinToString(".")}'", it.sourceLocation)
+              issues.add(FragmentCycle("Fragment '$name' spreads itself, creating a cycle at '${nextPath.subList(index, nextPath.size).joinToString(".")}'", it.sourceLocation))
               cyclicFragments.add(name)
               return@forEach
             }