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feat(anthropic): support extended thinking round trips #2233

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c825fc6
feat(anthropic): support extended thinking round trips
dailingtao Jul 15, 2026
705b4fe
fix(anthropic): preserve thinking with tool calls
dailingtao Jul 15, 2026
69702c9
fix(anthropic): harden thinking round trips
dailingtao Jul 15, 2026
d7f6dea
refactor(anthropic): focus extended thinking support
dailingtao Jul 15, 2026
33632b4
fix(anthropic): validate thinking metadata
dailingtao Jul 18, 2026
1bcd3d7
refactor(anthropic): preserve parser style
dailingtao Jul 18, 2026
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19 changes: 16 additions & 3 deletions agentscope-core/src/main/java/io/agentscope/core/agent/accumulator/ThinkingAccumulator.java
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,8 @@

import io.agentscope.core.message.ContentBlock;
import io.agentscope.core.message.ThinkingBlock;
import java.util.HashMap;
import java.util.Map;

/**
* Thinking content accumulator for accumulating streaming thinking chunks.
Expand All @@ -28,23 +30,30 @@
public class ThinkingAccumulator implements ContentAccumulator<ThinkingBlock> {

private final StringBuilder accumulated = new StringBuilder();
private final Map<String, Object> metadata = new HashMap<>();

/**
* @hidden
*/
@Override
public void add(ThinkingBlock block) {
if (block != null && block.getThinking() != null) {
if (block == null) {
return;
}
if (block.getThinking() != null) {
accumulated.append(block.getThinking());
}
if (block.getMetadata() != null && !block.getMetadata().isEmpty()) {
metadata.putAll(block.getMetadata());
}
}

/**
* @hidden
*/
@Override
public boolean hasContent() {
return accumulated.length() > 0;
return accumulated.length() > 0 || !metadata.isEmpty();
}

/**
Expand All @@ -55,7 +64,10 @@ public ContentBlock buildAggregated() {
if (!hasContent()) {
return null;
}
return ThinkingBlock.builder().thinking(accumulated.toString()).build();
return ThinkingBlock.builder()
.thinking(accumulated.toString())
.metadata(metadata.isEmpty() ? null : metadata)
.build();
}

/**
Expand All @@ -64,6 +76,7 @@ public ContentBlock buildAggregated() {
@Override
public void reset() {
accumulated.setLength(0);
metadata.clear();
}

/**
Expand Down
49 changes: 49 additions & 0 deletions agentscope-core/src/test/java/io/agentscope/core/agent/accumulator/ReasoningContextTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -22,10 +22,12 @@

import io.agentscope.core.message.Msg;
import io.agentscope.core.message.TextBlock;
import io.agentscope.core.message.ThinkingBlock;
import io.agentscope.core.message.ToolUseBlock;
import io.agentscope.core.model.ChatResponse;
import io.agentscope.core.model.ChatUsage;
import java.util.List;
import java.util.Map;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;
Expand Down Expand Up @@ -169,6 +171,53 @@ void testChunksWithoutUsage() {
assertNull(resultUsage);
}

@Test
@DisplayName("Should preserve metadata-only thinking blocks")
void testMetadataOnlyThinkingBlock() {
ThinkingBlock thinkingBlock =
ThinkingBlock.builder()
.metadata(Map.of("signature", "encrypted-signature"))
.build();
ChatResponse chunk =
ChatResponse.builder().id("msg-1").content(List.of(thinkingBlock)).build();

context.processChunk(chunk);

Msg msg = context.buildFinalMessage();
assertNotNull(msg);
ThinkingBlock result = msg.getFirstContentBlock(ThinkingBlock.class);
assertNotNull(result);
assertEquals("", result.getThinking());
assertEquals("encrypted-signature", result.getMetadata().get("signature"));
}

@Test
@DisplayName("Should merge thinking text and metadata across chunks")
void testThinkingTextAndMetadataAccumulation() {
ChatResponse textChunk =
ChatResponse.builder()
.id("msg-1")
.content(List.of(ThinkingBlock.builder().thinking("Reasoning").build()))
.build();
ChatResponse metadataChunk =
ChatResponse.builder()
.id("msg-1")
.content(
List.of(
ThinkingBlock.builder()
.metadata(Map.of("signature", "signature-123"))
.build()))
.build();

context.processChunk(textChunk);
context.processChunk(metadataChunk);

ThinkingBlock result =
context.buildFinalMessage().getFirstContentBlock(ThinkingBlock.class);
assertEquals("Reasoning", result.getThinking());
assertEquals("signature-123", result.getMetadata().get("signature"));
}

@Test
@DisplayName("Should handle mixed chunks with and without usage")
void testMixedChunksWithAndWithoutUsage() {
Expand Down
18 changes: 12 additions & 6 deletions ...in/java/io/agentscope/extensions/model/anthropic/formatter/AnthropicMessageConverter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -257,12 +257,18 @@ private MessageParam convertMessageContent(
ContentBlockParam.ofText(
TextBlockParam.builder().text(hb.getHint()).build()));
} else if (block instanceof ThinkingBlock thinkingBlock) {
// Anthropic supports thinking blocks natively
contentBlocks.add(
ContentBlockParam.ofText(
TextBlockParam.builder()
.text(thinkingBlock.getThinking())
.build()));
List<ContentBlockParam> nativeThinkingBlocks =
AnthropicThinkingMetadata.toContentBlockParams(thinkingBlock);
if (!nativeThinkingBlocks.isEmpty()) {
contentBlocks.addAll(nativeThinkingBlocks);
} else {
// Preserve compatibility with thinking blocks produced by other providers.
contentBlocks.add(
ContentBlockParam.ofText(
TextBlockParam.builder()
.text(thinkingBlock.getThinking())
.build()));
}
} else if (block instanceof ImageBlock ib) {
try {
ImageBlockParam imageParam = mediaConverter.convertImageBlock(ib);
Expand Down
111 changes: 97 additions & 14 deletions ...main/java/io/agentscope/extensions/model/anthropic/formatter/AnthropicResponseParser.java
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@
import java.time.Duration;
import java.time.Instant;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.slf4j.Logger;
Expand All @@ -50,7 +51,9 @@ public static ChatResponse parseMessage(Message message, Instant startTime) {
List<ContentBlock> contentBlocks = new ArrayList<>();

// Process content blocks
for (var block : message.content()) {
for (int index = 0; index < message.content().size(); index++) {
final int blockIndex = index;
var block = message.content().get(index);
// Text block
block.text()
.ifPresent(
Expand Down Expand Up @@ -83,6 +86,25 @@ public static ChatResponse parseMessage(Message message, Instant startTime) {
contentBlocks.add(
ThinkingBlock.builder()
.thinking(thinking.thinking())
.metadata(
AnthropicThinkingMetadata.thinking(
blockIndex,
thinking.thinking(),
thinking.signature()))
.build()));

// Redacted thinking block
block.redactedThinking()
.ifPresent(
redactedThinking ->
contentBlocks.add(
ThinkingBlock.builder()
.metadata(
AnthropicThinkingMetadata
.redactedThinking(
blockIndex,
redactedThinking
.data()))
.build()));
}

Expand All @@ -102,23 +124,33 @@ public static ChatResponse parseMessage(Message message, Instant startTime) {
*/
public static Flux<ChatResponse> parseStreamEvents(
Flux<RawMessageStreamEvent> eventFlux, Instant startTime) {
return eventFlux
.flatMap(
event -> {
try {
return Flux.just(parseStreamEvent(event, startTime));
} catch (Exception e) {
log.warn("Error parsing stream event: {}", e.getMessage());
return Flux.empty();
}
})
.filter(response -> response != null && !response.getContent().isEmpty());
return Flux.defer(
() -> {
StreamState streamState = new StreamState();
return eventFlux.<ChatResponse>handle(
(event, sink) -> {
try {
ChatResponse response =
parseStreamEvent(event, startTime, streamState);
if (response != null && !response.getContent().isEmpty()) {
sink.next(response);
}
} catch (Exception e) {
log.warn("Error parsing stream event: {}", e.getMessage());
}
});
});
}

/**
* Parse single stream event.
*/
private static ChatResponse parseStreamEvent(RawMessageStreamEvent event, Instant startTime) {
return parseStreamEvent(event, startTime, new StreamState());
}

private static ChatResponse parseStreamEvent(
RawMessageStreamEvent event, Instant startTime, StreamState streamState) {
List<ContentBlock> contentBlocks = new ArrayList<>();
ChatUsage usage = null;
String messageId = null;
Expand All @@ -144,10 +176,28 @@ private static ChatResponse parseStreamEvent(RawMessageStreamEvent event, Instan
.delta()
.thinking()
.ifPresent(
thinkingDelta ->
thinkingDelta -> {
streamState.appendThinking(
deltaEvent.index(), thinkingDelta.thinking());
contentBlocks.add(
ThinkingBlock.builder()
.thinking(thinkingDelta.thinking())
.build());
});

deltaEvent
.delta()
.signature()
.ifPresent(
signatureDelta ->
contentBlocks.add(
ThinkingBlock.builder()
.thinking(thinkingDelta.thinking())
.metadata(
AnthropicThinkingMetadata.thinking(
deltaEvent.index(),
streamState.getThinking(
deltaEvent.index()),
signatureDelta.signature()))
.build()));

// Input JSON delta (tool calling)
Expand All @@ -171,6 +221,21 @@ private static ChatResponse parseStreamEvent(RawMessageStreamEvent event, Instan
if (event.isContentBlockStart()) {
var startEvent = event.asContentBlockStart();

startEvent
.contentBlock()
.redactedThinking()
.ifPresent(
redactedThinking ->
contentBlocks.add(
ThinkingBlock.builder()
.metadata(
AnthropicThinkingMetadata
.redactedThinking(
startEvent.index(),
redactedThinking
.data()))
.build()));

startEvent
.contentBlock()
.toolUse()
Expand Down Expand Up @@ -199,6 +264,24 @@ private static ChatResponse parseStreamEvent(RawMessageStreamEvent event, Instan
return ChatResponse.builder().id(messageId).content(contentBlocks).usage(usage).build();
}

private static final class StreamState {

private final Map<Long, StringBuilder> thinkingByIndex = new HashMap<>();

private void appendThinking(long index, String thinking) {
if (thinking != null && !thinking.isEmpty()) {
thinkingByIndex
.computeIfAbsent(index, ignored -> new StringBuilder())
.append(thinking);
}
}

private String getThinking(long index) {
StringBuilder thinking = thinkingByIndex.get(index);
return thinking != null ? thinking.toString() : "";
}
}

/**
* Parse JsonValue to Map for tool input.
*/
Expand Down
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