feat(session): 新增 Session 标题豁免前缀，过滤注入式 Prompt 候选

src/coding/proxy/config/config.default.yaml

@@ -704,3 +704,10 @@ session_policies:
   title_vendor_bindings:
     - prefix: "# 目标"
       vendor: "zhipu"
+  # Session 标题豁免前缀：user 输入（经噪声剥离清洗后）以任一前缀开头则跳过，
+  # 继续向后查找 title 候选。用于过滤注入式 Prompt（如示例语言指令），
+  # 避免其被误用作 Session 标题。大小写敏感 startswith。
+  # ⚠️ 自定义 yaml 中该字段为整体替换（loader 的 list 合并约定，非追加合并）；
+  #    写空列表即关闭豁免。加载时会自动 strip + 去空 + 去重。
+  title_exempt_prefixes:
+    - "Write the title in the language"

src/coding/proxy/config/session_policy.py

@@ -2,7 +2,7 @@
 
 from __future__ import annotations
 
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, field_validator
 
 
 class SessionPolicyMatch(BaseModel):
@@ -81,3 +81,34 @@ class SessionPoliciesConfig(BaseModel):
             "匹配规则按列表顺序求值，首次匹配生效。"
         ),
     )
+    title_exempt_prefixes: list[str] = Field(
+        default_factory=list,
+        description=(
+            "Session 标题豁免前缀名单。当首条 user TEXT 输入（经噪声剥离清洗后）"
+            "以任一前缀开头时，跳过该输入、继续向后查找合适的 title 候选。"
+            "用于过滤注入式 Prompt（如示例语言指令），避免其被误用作 Session 标题。"
+            "大小写敏感的 startswith 匹配，与 title_vendor_bindings 语义一致。"
+            "加载时会自动 strip + 去空 + 去重；空字符串前缀会被丢弃"
+            "（防空串 startswith 恒真导致全量误豁免）。"
+        ),
+    )
+
+    @field_validator("title_exempt_prefixes", mode="after")
+    @classmethod
+    def _normalize_exempt_prefixes(cls, value: list[str]) -> list[str]:
+        """归一化豁免前缀：strip + 去空 + 去重保序.
+
+        空字符串前缀必须丢弃——``"".startswith`` 恒真会豁免一切用户输入，
+        导致 Level 1 标题提取永久失效。
+        """
+        seen: set[str] = set()
+        result: list[str] = []
+        for item in value:
+            if not isinstance(item, str):
+                continue
+            cleaned = item.strip()
+            if not cleaned or cleaned in seen:
+                continue
+            seen.add(cleaned)
+            result.append(cleaned)
+        return result

src/coding/proxy/routing/executor.py

@@ -148,14 +148,30 @@ def _sanitize_user_text(raw: str) -> str:
 # ─────────────────────────────────────────────────────────────────
 
 
-def _extract_title_from_user_text(messages: list[CanonicalMessagePart]) -> str:
-    """Level 1: 从 user TEXT 部分提取经噪声剥离后的首条非空文本."""
+def _extract_title_from_user_text(
+    messages: list[CanonicalMessagePart],
+    exempt_prefixes: list[str] | None = None,
+) -> str:
+    """Level 1: 从 user TEXT 部分提取经噪声剥离后的首条非空文本.
+
+    ``exempt_prefixes`` 非空时，清洗后文本以任一前缀开头则跳过该输入、继续向后
+    查找——用于过滤注入式 Prompt，避免其被误用作 Session 标题。匹配作用于
+    ``_sanitize_user_text`` 清洗后的纯文本（而非带 XML 标签的原始 raw）。
+    """
     for part in messages:
         if part.role != "user" or part.type != CanonicalPartType.TEXT:
             continue
         cleaned = _sanitize_user_text(part.text)
-        if cleaned:
-            return cleaned[:_SESSION_TITLE_MAX_LEN]
+        if not cleaned:
+            continue
+        if exempt_prefixes and any(cleaned.startswith(p) for p in exempt_prefixes):
+            logger.debug(
+                "Title candidate skipped by exempt prefix %r (snippet=%r)",
+                next(p for p in exempt_prefixes if cleaned.startswith(p)),
+                cleaned[:60],
+            )
+            continue
+        return cleaned[:_SESSION_TITLE_MAX_LEN]
     return ""
 
 
@@ -193,15 +209,24 @@ def _extract_title_from_metadata(request: CanonicalRequest) -> str:
     return ""
 
 
-def _extract_session_title(request: CanonicalRequest) -> str:
+def _extract_session_title(
+    request: CanonicalRequest,
+    exempt_prefixes: list[str] | None = None,
+) -> str:
     """从规范化请求中提取 session 标题 — 多层级回退策略。
 
     依次尝试: user TEXT 噪声剥离 → TOOL_RESULT 摘要 → IMAGE 计数 → 元数据兜底。
     任意级别命中即返回,确保 Dashboard 尽可能展示有辨识度的标题。
+
+    ``exempt_prefixes`` 仅作用于 Level 1（用户直接输入的 TEXT）；Level 2/3/4
+    为非用户直接输入的回退来源,不参与豁免。默认 ``None`` 时行为与历史一致。
     """
     messages = request.messages
+    # Level 1 需要豁免前缀；单独调用以传入参数，避免污染 L2/L3 的统一签名。
+    title = _extract_title_from_user_text(messages, exempt_prefixes)
+    if title:
+        return title[:_SESSION_TITLE_MAX_LEN]
     for extractor in (
-        _extract_title_from_user_text,
         _extract_title_from_tool_results,
         _extract_title_from_images,
     ):
@@ -614,6 +639,7 @@ def __init__(
         reauth_coordinator: Any | None = None,
         session_policy_resolver: SessionPolicyResolver | None = None,
         title_vendor_bindings: list[TitleVendorBinding] | None = None,
+        title_exempt_prefixes: list[str] | None = None,
     ) -> None:
         self._router = router
         self._tiers = tiers
@@ -622,6 +648,13 @@ def __init__(
         self._reauth_coordinator = reauth_coordinator
         self._policy_resolver = session_policy_resolver or SessionPolicyResolver()
         self._title_vendor_bindings = title_vendor_bindings or []
+        # 豁免前缀名单：构造期二次归一化（strip + 去空），双重防御配置层 field_validator。
+        # 即便绕过配置层直接构造 executor，也能避免空串 startswith 恒真与纯空白失配。
+        self._title_exempt_prefixes: list[str] = [
+            stripped
+            for p in (title_exempt_prefixes or [])
+            if isinstance(p, str) and (stripped := p.strip())
+        ]
         self._validate_title_vendor_bindings()
 
         # Tier 名称 → OAuth provider 名称的映射
@@ -676,6 +709,17 @@ def _resolve_effective_tiers(self, session_key: str) -> list[VendorTier]:
                 seen.add(tier.name)
         return ordered
 
+    def _extract_session_title(self, request: CanonicalRequest) -> str:
+        """封装模块级标题提取，注入实例持有的豁免前缀名单.
+
+        将 ``self._title_exempt_prefixes`` 透传给模块级 ``_extract_session_title``，
+        使 Level 1 能跳过以豁免前缀开头的注入式 Prompt。4 处标题提取调用点统一
+        经此方法，避免重复透传（零透传污染）。
+        """
+        return _extract_session_title(
+            request, exempt_prefixes=self._title_exempt_prefixes
+        )
+
     def _apply_title_based_policy(self, session_key: str, title: str) -> None:
         """根据 Session 标题前缀自动绑定供应商.
 
@@ -790,15 +834,15 @@ async def execute_stream(
             canonical_request.trace_id,
         )
         if is_new_session:
-            title = _extract_session_title(canonical_request)
+            title = self._extract_session_title(canonical_request)
             if title:
                 await self._recorder.set_session_title(
                     canonical_request.session_key, title
                 )
                 self._apply_title_based_policy(canonical_request.session_key, title)
         else:
             # 延迟标题补写: 若 session 尚无标题,尝试从当前请求中提取并回写。
-            title = _extract_session_title(canonical_request)
+            title = self._extract_session_title(canonical_request)
             if title:
                 await self._recorder.update_empty_session_title(
                     canonical_request.session_key, title
@@ -977,15 +1021,15 @@ async def execute_message(
             canonical_request.trace_id,
         )
         if is_new_session:
-            title = _extract_session_title(canonical_request)
+            title = self._extract_session_title(canonical_request)
             if title:
                 await self._recorder.set_session_title(
                     canonical_request.session_key, title
                 )
                 self._apply_title_based_policy(canonical_request.session_key, title)
         else:
             # 延迟标题补写: 若 session 尚无标题,尝试从当前请求中提取并回写。
-            title = _extract_session_title(canonical_request)
+            title = self._extract_session_title(canonical_request)
             if title:
                 await self._recorder.update_empty_session_title(
                     canonical_request.session_key, title

src/coding/proxy/routing/router.py

@@ -40,6 +40,7 @@ def __init__(
         compat_session_store: CompatSessionStore | None = None,
         session_policy_resolver: SessionPolicyResolver | None = None,
         title_vendor_bindings: list[TitleVendorBinding] | None = None,
+        title_exempt_prefixes: list[str] | None = None,
     ) -> None:
         if not tiers:
             raise ValueError("至少需要一个供应商层级")
@@ -59,6 +60,7 @@ def __init__(
             reauth_coordinator=reauth_coordinator,
             session_policy_resolver=session_policy_resolver,
             title_vendor_bindings=title_vendor_bindings,
+            title_exempt_prefixes=title_exempt_prefixes,
         )
 
     def set_pricing_table(self, table: PricingTable) -> None:

src/coding/proxy/server/app.py

@@ -162,6 +162,7 @@ def create_app(config: ProxyConfig | None = None) -> FastAPI:
         compat_session_store,
         session_policy_resolver=SessionPolicyResolver(config.session_policies.policies),
         title_vendor_bindings=config.session_policies.title_vendor_bindings,
+        title_exempt_prefixes=config.session_policies.title_exempt_prefixes,
     )
 
     app = FastAPI(title="coding-proxy", version=__version__, lifespan=lifespan)