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77169b4 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 | """会话指纹：基于 system prompt + 首条 user 消息计算 SHA-256 指纹。
同一逻辑对话（相同 system + 相同首条 user）的指纹恒定，
不同对话指纹不同，杜绝上下文污染。
"""
import hashlib
from core.api.schemas import OpenAIMessage
def _norm_content(content: str | list | None) -> str:
if content is None:
return ""
if isinstance(content, str):
return content.strip()
# list[OpenAIContentPart]
parts: list[str] = []
for p in content:
if hasattr(p, "type") and p.type == "text" and p.text:
parts.append(p.text.strip())
return " ".join(parts)
def compute_conversation_fingerprint(messages: list[OpenAIMessage]) -> str:
"""sha256(system_prompt + first_user_message)[:16]
Returns empty string if no user message found.
"""
system_text = ""
first_user_text = ""
for m in messages:
if m.role == "system" and not system_text:
system_text = _norm_content(m.content)
elif m.role == "user" and not first_user_text:
first_user_text = _norm_content(m.content)
break
if not first_user_text:
return ""
raw = f"{system_text}\n{first_user_text}"
return hashlib.sha256(raw.encode()).hexdigest()[:16]
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