fix(agent): retry empty LLM completion before treating it as final answer

mateclaw-server/src/main/java/vip/mate/agent/graph/node/ReasoningNode.java

@@ -82,6 +82,36 @@ public class ReasoningNode implements NodeAction {
      */
     private static final int DASHSCOPE_MAX_OUTPUT_TOKENS = 8192;
 
+    /**
+     * Max times to re-prompt the model when it returns a completely empty turn
+     * (no tool call, no content, no thinking) before accepting termination.
+     * A blank turn is otherwise treated as a final answer and ends the run; on
+     * long multi-step tasks that surfaces as the agent quitting mid-way.
+     */
+    private static final int MAX_EMPTY_COMPLETION_RETRIES = 2;
+
+    /** Continuation nudge appended to the prompt when the model returns an empty turn. */
+    private static final String EMPTY_COMPLETION_NUDGE =
+            "Your previous turn was empty. If the task is not yet complete, continue now "
+            + "with the next concrete step — call a tool or write the next part. If every "
+            + "required step is already done, output the final answer to the user now.";
+
+    /**
+     * A turn carrying no tool call, no content, and no thinking is not a usable
+     * answer — it would route to the final-answer branch as an empty string and
+     * terminate the run. Fatal / prompt-too-long / partial results are handled by
+     * their own branches and must not be misread as "empty".
+     */
+    static boolean isEmptyCompletion(NodeStreamingChatHelper.StreamResult result) {
+        if (result == null || result.hasToolCalls() || result.hasFatalError()
+                || result.isPromptTooLong() || result.partial()) {
+            return false;
+        }
+        boolean noContent = result.text() == null || result.text().isBlank();
+        boolean noThinking = result.thinking() == null || result.thinking().isBlank();
+        return noContent && noThinking;
+    }
+
     /**
      * Tool-use enforcement clause appended to every ReasoningNode
      * system prompt. Treats narration ("I will now …") as a protocol violation
@@ -519,6 +549,28 @@ public class ReasoningNode implements NodeAction {
                     log.warn("[ReasoningNode] Compaction did not reduce messages, cannot retry");
                 }
             }
+
+            // Empty-completion guard: a turn with no tool call, no content, and
+            // no thinking is not a real answer. Under heavy message-window
+            // trimming on long multi-step tasks the model occasionally emits a
+            // blank turn; the final-answer branch would then treat it as "done"
+            // (finalAnswer="") and end the run prematurely (observed: a 10-item
+            // research task stopping at item 2). Re-prompt it to continue —
+            // bounded, so a model that genuinely has nothing left still
+            // terminates cleanly through the normal empty-answer path below.
+            int emptyRetries = 0;
+            while (emptyRetries < MAX_EMPTY_COMPLETION_RETRIES && isEmptyCompletion(result)) {
+                emptyRetries++;
+                log.warn("[ReasoningNode] Empty LLM completion (no tool call / content / thinking); "
+                                + "nudging to continue (retry {}/{}), conv={}",
+                        emptyRetries, MAX_EMPTY_COMPLETION_RETRIES, conversationId);
+                List<Message> nudgedMessages = new ArrayList<>(promptMessages);
+                nudgedMessages.add(new UserMessage(EMPTY_COMPLETION_NUDGE));
+                Prompt nudgePrompt = new Prompt(nudgedMessages, options);
+                nextLlmCallCount++;
+                result = streamingHelper.streamCall(
+                        chatModel, nudgePrompt, conversationId, "reasoning_empty_retry");
+            }
         } catch (CancellationException ce) {
             // "调用已发出但尚未产出内容时用户停止" — streamHelper 抛 CancellationException。
             // 返回空 finalAnswer + STOPPED，让 FinalAnswerNode 按 STOPPED 语义处理。

mateclaw-server/src/test/java/vip/mate/agent/graph/node/ReasoningNodeEmptyCompletionTest.java

@@ -0,0 +1,68 @@
+package vip.mate.agent.graph.node;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import vip.mate.agent.graph.NodeStreamingChatHelper.ErrorType;
+import vip.mate.agent.graph.NodeStreamingChatHelper.StreamResult;
+
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * Pins {@link ReasoningNode#isEmptyCompletion} — the predicate that decides
+ * whether a model turn is a blank no-op worth re-prompting (vs a real answer, a
+ * tool call, or a failure handled by another branch). A blank turn must NOT be
+ * accepted as a final answer; that is what made a long multi-step task quit
+ * mid-way.
+ */
+class ReasoningNodeEmptyCompletionTest {
+
+    private static StreamResult turn(String text, String thinking, boolean hasToolCalls) {
+        return new StreamResult(text, thinking, null, List.of(), hasToolCalls, 0, 0);
+    }
+
+    @Test
+    @DisplayName("No tool call + blank text + blank thinking → empty (re-prompt).")
+    void blankTurnIsEmpty() {
+        assertTrue(ReasoningNode.isEmptyCompletion(turn("", "", false)));
+        assertTrue(ReasoningNode.isEmptyCompletion(turn("   ", "  ", false)));
+        assertTrue(ReasoningNode.isEmptyCompletion(turn(null, null, false)));
+    }
+
+    @Test
+    @DisplayName("Any content or thinking → not empty.")
+    void contentOrThinkingNotEmpty() {
+        assertFalse(ReasoningNode.isEmptyCompletion(turn("here is the answer", "", false)));
+        assertFalse(ReasoningNode.isEmptyCompletion(turn("", "let me reason", false)));
+    }
+
+    @Test
+    @DisplayName("A tool call is real progress → not empty.")
+    void toolCallNotEmpty() {
+        assertFalse(ReasoningNode.isEmptyCompletion(turn("", "", true)));
+    }
+
+    @Test
+    @DisplayName("null result → not empty (nothing to re-prompt).")
+    void nullNotEmpty() {
+        assertFalse(ReasoningNode.isEmptyCompletion(null));
+    }
+
+    @Test
+    @DisplayName("Fatal / prompt-too-long / partial belong to other branches, not 'empty'.")
+    void otherFailuresNotEmpty() {
+        StreamResult fatal = new StreamResult("", "", null, List.of(), false, 0, 0,
+                false, "upstream boom", ErrorType.SERVER_ERROR);
+        assertFalse(ReasoningNode.isEmptyCompletion(fatal));
+
+        StreamResult promptTooLong = new StreamResult("", "", null, List.of(), false, 0, 0,
+                false, null, ErrorType.PROMPT_TOO_LONG);
+        assertFalse(ReasoningNode.isEmptyCompletion(promptTooLong));
+
+        StreamResult partial = new StreamResult("", "", null, List.of(), false, 0, 0,
+                true, null, ErrorType.NONE);
+        assertFalse(ReasoningNode.isEmptyCompletion(partial));
+    }
+}