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fix: 抗截断模式适配 agent 工具调用场景，恢复流式输出并保留 finish_reason 收尾块 #415

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fix: 抗截断模式适配 agent 工具调用场景，恢复流式输出并保留 finish_reason 收尾块 #415

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65909a6
fix: 抗截断模式适配 agent 工具调用场景并保留 finish_reason 收尾块
Theater-ahyeon Sep 13, 2026
70f1d87
merge: reconcile streaming fixes with master and stop tool replay
Theater-ahyeon Sep 21, 2026
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103 changes: 40 additions & 63 deletions src/converter/anti_truncation.py
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Original file line number Diff line number Diff line change
Expand Up @@ -56,7 +56,6 @@
现在请继续输出："""



# ==================== 请求注入 ====================


Expand Down Expand Up @@ -126,8 +125,6 @@ def apply_anti_truncation(payload: Dict[str, Any]) -> Dict[str, Any]:
return modified_payload




# ==================== 响应提取 ====================


Expand Down Expand Up @@ -221,7 +218,6 @@ def _extract_content_from_json_str(args_str: str) -> Optional[str]:
return None



def build_text_chunk_from_synthetic(
original_data: Dict[str, Any],
synthetic_content: str,
Expand Down Expand Up @@ -288,8 +284,6 @@ def build_text_chunk_from_synthetic(
return modified_inner




# ==================== 流式处理器 ====================


Expand Down Expand Up @@ -354,7 +348,8 @@ async def process_stream(self) -> AsyncGenerator[bytes, None]:
# 每轮流内状态：初始化放在 try 之外，流中断的异常路径需要访问
found_synthetic = False
has_real_tool_calls = False
side_buffer = io.StringIO() # 暂存普通文本（防拼接）
emitted_text = False
side_buffer = io.StringIO() # 保存已透传正文，供异常中断后续传
last_finish_reason: Optional[str] = None

try:
Expand Down Expand Up @@ -444,14 +439,14 @@ async def process_stream(self) -> AsyncGenerator[bytes, None]:
synthetic_content, real_calls, chunk_has_synthetic = (
extract_synthetic_content_from_response(data)
)
has_real_tool_calls = has_real_tool_calls or bool(real_calls)

if chunk_has_synthetic:
found_synthetic = True
# 防拼接：丢弃之前暂存的普通文本
if side_buffer.getvalue():
if emitted_text:
print(
"Anti-truncation: Discarding side-buffered text "
"(content conflict with synthetic tool)",
"Anti-truncation: Plain text was streamed before "
"synthetic tool call (possible duplication)",
flush=True,
)
side_buffer.close()
Expand All @@ -471,7 +466,6 @@ async def process_stream(self) -> AsyncGenerator[bytes, None]:

elif real_calls:
# 真实工具调用，原样透传
has_real_tool_calls = True
yield line

else:
Expand All @@ -487,24 +481,25 @@ async def process_stream(self) -> AsyncGenerator[bytes, None]:
stripped, separators=(",", ":"), ensure_ascii=False
)
yield f"data: {json_str}\n\n".encode("utf-8")
elif not self._chunk_has_plain_text(data):
yield line
continue
else:
# 暂存到 side buffer，等待看是否有合成工具调用
text = self._extract_text_from_chunk(data)
if text:
side_buffer.write(text)
# 正文与思考实时透传；正文另存一份用于异常续传历史。
if self._chunk_has_plain_text(data):
emitted_text = True
side_buffer.write(self._extract_text_from_chunk(data))
chunk_finish = self._get_finish_reason(data)
if chunk_finish:
last_finish_reason = chunk_finish
# 暂时不透传，等流结束时决定
yield line
continue

else:
# 非 data: 开头的行，直接传递
yield line

# 流结束（break 或正常结束）
side_text = side_buffer.getvalue()
side_buffer.close()

if found_synthetic:
Expand All @@ -514,41 +509,17 @@ async def process_stream(self) -> AsyncGenerator[bytes, None]:
yield b"data: [DONE]\n\n"
return

# 模型自然结束（STOP）且未调用合成工具：视为完整回答，不再续传
# （续传会让模型重发一遍已有内容，浪费上游请求且可能产生重复文本）
if last_finish_reason == "STOP":
# 真实工具或正文已交给客户端，不能续传重放；保留上游 STOP 终止语义。
if has_real_tool_calls or emitted_text or last_finish_reason == "STOP":
print(
f"Anti-truncation: Stream ended with STOP without synthetic tool call "
f"(text length: {len(side_text)}), treating as complete",
"Anti-truncation: Real output or STOP received, treating turn as complete",
flush=True,
)
if side_text:
# 输出暂存文本（正常情况下模型守规矩时不会走到这里）
self._append_content(side_text)
fallback_chunk = self._build_fallback_text_chunk(side_text)
if fallback_chunk:
yield fallback_chunk
self._clear_content()
# 补发 finishReason 收尾 chunk（Gemini 客户端靠它判断流正常结束）
yield self._build_finish_reason_chunk()
yield b"data: [DONE]\n\n"
return

# 未收到合成工具调用
if side_text:
# 有普通文本作为 fallback，输出它
print(
f"Anti-truncation: No synthetic tool call, "
f"using side-buffered text as fallback (length: {len(side_text)})",
flush=True,
)
self._append_content(side_text)
# 构建一个包含 side buffer 文本的 chunk 输出
fallback_chunk = self._build_fallback_text_chunk(side_text)
if fallback_chunk:
yield fallback_chunk

# 触发续传
# 正常结束但没有正文或工具产出（如纯思考）才触发续传。
if self.current_attempt < self.max_attempts:
accumulated_text = self._get_collected_text()
total_length = len(accumulated_text)
Expand Down Expand Up @@ -580,20 +551,12 @@ async def process_stream(self) -> AsyncGenerator[bytes, None]:
)
self._append_content(interrupted_text)

if self.current_attempt >= self.max_attempts:
# 重试额度用尽：把已收到的内容（含残文）作为 fallback 输出，尽量不浪费
if has_real_tool_calls or self.current_attempt >= self.max_attempts:
# 工具已经发出时必须报错终止，续传可能导致客户端重复执行。
# 正文已实时发送；重试额度用尽时不能再次输出整个历史。
salvaged = self._get_collected_text()
self._clear_content()
if salvaged:
print(
f"Anti-truncation: Max attempts reached after error, "
f"yielding salvaged text (length: {len(salvaged)})",
flush=True,
)
fallback_chunk = self._build_fallback_text_chunk(salvaged)
if fallback_chunk:
yield fallback_chunk
else:
if has_real_tool_calls or not salvaged:
error_chunk = {
"error": {
"message": f"Anti-truncation failed: {str(e)}",
Expand Down Expand Up @@ -633,8 +596,8 @@ def _build_current_payload(self) -> Dict[str, Any]:
if accumulated_text:
new_contents.append({"role": "model", "parts": [{"text": accumulated_text}]})

# 预填充模式：直接用拼接内容作为末尾 model 预填充
if self.enable_prefill_mode:
# 没有正文可续写时使用明确的续传指令，避免空预填充原样重发。
if self.enable_prefill_mode and accumulated_text:
request_data["contents"] = new_contents
continuation_payload["request"] = request_data
return continuation_payload
Expand Down Expand Up @@ -669,10 +632,21 @@ def _extract_text_from_chunk(self, data: Dict[str, Any]) -> str:
for candidate in data.get("candidates", []):
content = candidate.get("content", {})
for part in content.get("parts", []):
if isinstance(part, dict) and "text" in part:
if isinstance(part, dict) and "text" in part and not part.get("thought", False):
text += part["text"]
return text

@staticmethod
def _chunk_has_plain_text(data: Dict[str, Any]) -> bool:
"""非空正文才算产出；思考与空文本收尾块不算。"""
if "response" in data:
data = data["response"]
return any(
isinstance(part, dict) and part.get("text") and not part.get("thought", False)
for candidate in data.get("candidates", [])
for part in candidate.get("content", {}).get("parts", [])
)

@staticmethod
def _has_finish_reason(data: Dict[str, Any]) -> bool:
"""判断 chunk 是否携带 finishReason（控制信号 chunk）。"""
Expand Down Expand Up @@ -822,6 +796,11 @@ async def _handle_non_streaming_response(self, response) -> bytes:
extract_synthetic_content_from_response(response_data)
)

if not found_synthetic and (
real_calls or self._chunk_has_plain_text(response_data)
):
return content.encode() if isinstance(content, str) else content

if found_synthetic or self.current_attempt >= self.max_attempts:
if found_synthetic:
# 替换响应中的合成工具调用为普通文本
Expand Down Expand Up @@ -856,5 +835,3 @@ async def _handle_non_streaming_response(self, response) -> bytes:
}
}
).encode()


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