fix: never retry a WorkflowConfigurationException

core/src/main/java/com/google/adk/workflow/RetryConfig.java

@@ -72,7 +72,9 @@ public abstract class RetryConfig {
 
   /**
    * Returns the simple type names of the failures to retry on, matched exactly with no subclass
-   * match. When unset, any failure is retried; an empty list retries none.
+   * match. When unset, any failure is retried; an empty list retries none. A {@link
+   * WorkflowConfigurationException} is never retried, even when listed, because a retry fails the
+   * same way.
    */
   public abstract Optional<ImmutableList<String>> exceptions();
 
@@ -92,7 +94,7 @@ public static Builder builder() {
    * from 1, has an attempt left and failed with a type this config retries.
    */
   boolean shouldRetry(Exception failure, int attempt) {
-    if (attempt >= maxAttempts()) {
+    if (attempt >= maxAttempts() || failure instanceof WorkflowConfigurationException) {
       return false;
     }
     return exceptions().map(names -> names.contains(errorTypeName(failure))).orElse(true);

core/src/test/java/com/google/adk/workflow/RetryConfigTest.java

@@ -181,6 +181,18 @@ public void shouldRetry_withAnEmptyExceptionsList_retriesNothing() {
     assertThat(config.shouldRetry(new IllegalStateException(), /* attempt= */ 1)).isFalse();
   }
 
+  @Test
+  public void shouldRetry_neverRetriesAWorkflowConfigurationException() {
+    Exception failure = new WorkflowConfigurationException("misconfigured");
+    RetryConfig listingIt =
+        RetryConfig.builder()
+            .exceptions(ImmutableList.of("WorkflowConfigurationException"))
+            .build();
+
+    assertThat(RetryConfig.builder().build().shouldRetry(failure, /* attempt= */ 1)).isFalse();
+    assertThat(listingIt.shouldRetry(failure, /* attempt= */ 1)).isFalse();
+  }
+
   @Test
   public void delayFor_withoutJitter_growsByTheBackoffFactorUntilMaxDelay() {
     RetryConfig config =

core/src/test/java/com/google/adk/workflow/WorkflowRetryTest.java

@@ -17,6 +17,7 @@
 package com.google.adk.workflow;
 
 import static com.google.adk.testing.WorkflowTestNodes.dispatcher;
+import static com.google.adk.testing.WorkflowTestNodes.emitter;
 import static com.google.adk.testing.WorkflowTestNodes.throwing;
 import static com.google.adk.testing.WorkflowTestNodes.workflow;
 import static com.google.adk.workflow.WorkflowResumeTesting.START;
@@ -383,6 +384,23 @@ public void anOuterTimeout_isNeitherBlamedOnNorRetriedByTheNodeItCancels() {
     assertThat(errorPaths(turn.events())).containsExactly("wf@1");
   }
 
+  @Test
+  public void aWorkflowWithTwoTerminalOutputs_failsWithoutARetry() {
+    Workflow root =
+        Workflow.builder()
+            .name("wf")
+            .edges(
+                new Edge(START, emitter("first", "first_out")),
+                new Edge(START, emitter("second", "second_out")))
+            .config(retrying(3))
+            .build();
+
+    FailedTurn turn = new WorkflowSession(root).failingTurn(go());
+
+    assertThat(turn.error()).isInstanceOf(WorkflowConfigurationException.class);
+    assertThat(errorPaths(turn.events())).containsExactly("wf@1");
+  }
+
   @Test
   public void aWorkflowRetriedAfterANodeFailed_replaysTheNodesThatFinished() {
     CountingNode first = new CountingNode("first", (ctx, run) -> Flowable.just("first_out"));