[Bug/错误]: signature_delta attached to wrong block in Anthropic response

### Pre-submission Checklist / 提交前检查

- [x] I have searched the [existing issues](https://github.com/looplj/axonhub/issues) and this bug has not been reported / 我已搜索现有 issues，此 Bug 尚未被报告
- [x] I have read the [documentation](https://github.com/looplj/axonhub#readme) / 我已阅读文档
- [x] I am using the latest version of AxonHub / 我正在使用 AxonHub 的最新版本

### Bug Description / Bug 描述

通过 AxonHub 使用 Claude Code，发现经常一个 prompt 发起两个请求，一个流式，一个非流式。

`claude --debug` 的日志中可以看到 streaming error 的错误：
```
2026-03-19T11:34:48.362Z [DEBUG] Stream started - received first chunk
2026-03-19T11:34:49.881Z [ERROR] Error streaming, falling back to non-streaming mode: Content block is not a thinking block
```

最近的 Claude Code 更新，支持了显示 streaming 的内容，经常会发现常常流式输出完后，突然整个文本块变了。
即虽然流式产生了错误，但客户端仍在继续显示，并在后续同步请求完成后替换了这个文本快。

### Steps to Reproduce / 复现步骤

1. 在 Claude Code 里通过 AxonHub 使用 Opus，可以使用 `claude --debug` 打开调试日志
2. `/effort high`
3. prompt 「请帮我看看这个目录下有什么」
4. 稍等片刻，在 AxonHub 里看到至少两个请求，一个是流式的，一个是非流式的。此时，`claude --debug` 的日志文件中也可见到错误。
```
2026-03-19T11:34:48.362Z [DEBUG] Stream started - received first chunk
2026-03-19T11:34:49.881Z [ERROR] Error streaming, falling back to non-streaming mode: Content block is not a thinking block
```

### Expected Behavior / 期望行为

有个空的 thinking block, signature 在这个 thinking block，然后才是 tool_use。

```
event: message_start
data: {"type":"message_start","message":{"model":"claude-opus-4-6","id":"msg_111111111111111111111111","type":"message","role":"assistant","content":[],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":3,"cache_creation_input_tokens":0,"cache_read_input_tokens":24857,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":0},"output_tokens":11,"service_tier":"standard","inference_geo":"not_available"}}             }

event: content_block_start
data: {"type":"content_block_start","index":0,"content_block":{"type":"thinking","thinking":"","signature":""}     }

event: ping
data: {"type": "ping"}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"signature_delta","signature":"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"}               }

event: content_block_stop
data: {"type":"content_block_stop","index":0            }

event: content_block_start
data: {"type":"content_block_start","index":1,"content_block":{"type":"tool_use","id":"toolu_AAAAAAAAAAAAAAAAAAAAAAAA","name":"Bash","input":{},"caller":{"type":"direct"}}     }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"input_json_delta","partial_json":""} }

--- 省略若干 content_block_delta  ---

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"input_json_delta","partial_json":"tory\"}"}         }

event: content_block_stop
data: {"type":"content_block_stop","index":1        }
```

### Actual Behavior / 实际行为

空的 thinking block 丢了，signature 跑到后面的 tool_use block 去了。

```
event:message_start
data: {"type":"message_start","message":{"id":"msg_AAAAAAAAAAAAAAAAAAAAAAAA","type":"message","role":"assistant","content":[],"model":"claude-opus-4-6","usage":{"input_tokens":3,"output_tokens":11,"cache_creation_input_tokens":14929,"cache_read_input_tokens":10107,"cache_creation":{"ephemeral_5m_input_tokens":14929,"ephemeral_1h_input_tokens":0}}}}

event:content_block_start
data: {"type":"content_block_start","index":0,"content_block":{"type":"tool_use","id":"toolu_BBBBBBBBBBBBBBBBBBBBBBBB","name":"Bash","input":{}}}

event:content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"input_json_delta","partial_json":""}}

--- 省略若干 content_block_delta  ---

event:content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"input_json_delta","partial_json":"ory\"}"}}

event:content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"signature_delta","signature":"QVhOMTAxAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"}}
```

### Operating System / 操作系统

Linux (Other) / Linux（其他）

### AxonHub Version / AxonHub 版本

v0.9.18

### Usage Scenario / 使用场景

Claude Code

### API Format / API 格式

Anthropic - Messages (/v1/messages) / Anthropic Messages

### Channel Type / 渠道类型

Anthropic / Anthropic

### Logs / 日志

[redacted_axonhub_response.txt](https://github.com/user-attachments/files/26114604/redacted_axonhub_response.txt)
[redacted_upstream_response.txt](https://github.com/user-attachments/files/26114605/redacted_upstream_response.txt)

### Additional Context / 其他补充信息

<details><summary>Claude Opus 4.6 对 @anthropic-ai/claude-agent-sdk 的分析</summary>

根据代码分析，错误信息 `"Content block is not a thinking block"` 来自 streaming 事件处理中的 `content_block_delta` 分支。具体在这段逻辑中：

```javascript
case "content_block_delta": {
    let j8 = $6[J8.index]; // 根据 index 获取之前 content_block_start 创建的 block
    
    switch (J8.delta.type) {
        // ...
        case "signature_delta":
            if (j8.type !== "thinking")
                throw Error("Content block is not a thinking block");
            j8.signature = J8.delta.signature;
            break;
        case "thinking_delta":
            if (j8.type !== "thinking")
                throw Error("Content block is not a thinking block");
            j8.thinking += J8.delta.thinking;
            break;
    }
}
```

## 触发原因

API 在 streaming 过程中发送了一个 `thinking_delta` 或 `signature_delta` 事件，但该事件对应的 `content_block` index 指向的块**不是 `thinking` 类型**。

也就是说：
1. `content_block_start` 事件为某个 index 创建了一个非 thinking 类型的块（比如 `text` 或 `tool_use`）
2. 随后收到的 `thinking_delta` / `signature_delta` 却引用了同一个 index

这是一个 **API 服务端 streaming 的 bug**——content block 的 index 或类型出现了不一致。客户端的类型校验发现了这个不匹配，抛出异常后走到了 catch 分支：

```javascript
} catch (t) {
    // ...
    k(`Error streaming, falling back to non-streaming mode: ${s6(t)}`, {level: "error"});
    // --> 这就是你看到的那条日志
    // 然后发起 non-streaming fallback 请求 (CNq)
}
```

## 总结

| 项目 | 详情 |
|------|------|
| **错误来源** | 客户端 streaming 类型校验 |
| **直接原因** | 收到 `thinking_delta` 或 `signature_delta`，但对应 index 的 content block 不是 `thinking` 类型 |
| **根因** | API 服务端 streaming 返回了 index/类型不匹配的事件（服务端 bug 或瞬态错误） |
| **后续行为** | 客户端捕获异常，回退到 non-streaming 模式重新发送请求 |

这不是你这边能修的问题，是 Anthropic API streaming 端的一个偶发异常。fallback 机制正是为了应对这类情况——streaming 失败后用 non-streaming 兜底，保证请求最终能成功。
</details>


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[Bug/错误]: signature_delta attached to wrong block in Anthropic response #1105

Pre-submission Checklist / 提交前检查

Bug Description / Bug 描述

Steps to Reproduce / 复现步骤

Expected Behavior / 期望行为

Actual Behavior / 实际行为

Operating System / 操作系统

AxonHub Version / AxonHub 版本

Usage Scenario / 使用场景

API Format / API 格式

Channel Type / 渠道类型

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触发原因

总结

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项目	详情
错误来源	客户端 streaming 类型校验
直接原因	收到 `thinking_delta` 或 `signature_delta`，但对应 index 的 content block 不是 `thinking` 类型
根因	API 服务端 streaming 返回了 index/类型不匹配的事件（服务端 bug 或瞬态错误）
后续行为	客户端捕获异常，回退到 non-streaming 模式重新发送请求

[Bug/错误]: signature_delta attached to wrong block in Anthropic response #1105

Description

Pre-submission Checklist / 提交前检查

Bug Description / Bug 描述

Steps to Reproduce / 复现步骤

Expected Behavior / 期望行为

Actual Behavior / 实际行为

Operating System / 操作系统

AxonHub Version / AxonHub 版本

Usage Scenario / 使用场景

API Format / API 格式

Channel Type / 渠道类型

Logs / 日志

Additional Context / 其他补充信息

触发原因

总结

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