impl: #16 知识注入 L2 引擎层 — WikiGuideSection

- prompt_composer.py: 新增 WikiGuideSection 类（priority=60）
- task_handler.py: get_sections() 注入 WikiGuideSection
- mail_handler.py: get_sections() 注入 WikiGuideSection
- toolchain_handler.py: get_sections() 注入 WikiGuideSection

L0（gate-enforcer wiki-rule）和 L1（SOUL.md Red Flags）不在本仓库，
直接在对应文件修改。

设计文档：docs/design/16-knowledge-injection.md（v2 已合并）

src/daemon/mail_handler.py

@@ -9,7 +9,7 @@ import logging
 from pathlib import Path
 
 from src.daemon.base_task_handler import BaseTaskHandler, VerifyResult
-from src.daemon.prompt_composer import PromptComposer, PromptContext
+from src.daemon.prompt_composer import PromptComposer, PromptContext, WikiGuideSection
 from src.blackboard.db import get_connection
 
 logger = logging.getLogger("moziplus-v2.handler.mail")
@@ -36,7 +36,7 @@ class MailHandler(BaseTaskHandler):
         return composer.compose(context)
 
     def get_sections(self) -> list:
-        return [MailContextSection(), MailApiSection(), MailConstraintsSection()]
+        return [MailContextSection(), MailApiSection(), MailConstraintsSection(), WikiGuideSection()]
 
     def verify_completion(self, task_id: str, db_path: Path) -> VerifyResult:
         """Mail 完成验证：区分 inform/request。

src/daemon/prompt_composer.py

@@ -127,3 +127,27 @@ class PromptComposer:
             )
 
         return result
+
+
+# ---------------------------------------------------------------------------
+# WikiGuideSection — 知识查询引导段
+# ---------------------------------------------------------------------------
+class WikiGuideSection:
+    """知识查询引导段 — 引导 Agent 在关键决策点查 wiki-vault。"""
+
+    name: str = "wiki_guide"
+    priority: int = 60  # PRIORITY_EXTENSION
+
+    WIKI_GUIDE = (
+        "## 知识查询引导\n"
+        "涉及方案设计、编码实现、故障排查时，先查 wiki-vault 相关实践：\n"
+        "- 路径：/Volumes/KnowledgeBase/wiki-vault/\n"
+        "- 速查：index.md → grep 关键词 → summary 字段 → 按需读全文\n"
+        "- 查不到：在 _meta/knowledge-gaps.md 记录"
+    )
+
+    def render(self, context: "PromptContext") -> str:
+        return self.WIKI_GUIDE
+
+    def should_include(self, context: "PromptContext") -> bool:
+        return True

src/daemon/task_handler.py

@@ -10,7 +10,7 @@ from pathlib import Path
 from typing import Dict, Optional
 
 from src.daemon.base_task_handler import BaseTaskHandler, VerifyResult
-from src.daemon.prompt_composer import PromptComposer, PromptContext
+from src.daemon.prompt_composer import PromptComposer, PromptContext, WikiGuideSection
 from src.blackboard.db import get_connection
 
 logger = logging.getLogger("moziplus-v2.handler")
@@ -313,6 +313,7 @@ class TaskHandler(BaseTaskHandler):
             RoleSkillSection(),
             TaskApiSection(),
             TaskConstraintsSection(),
+            WikiGuideSection(),
         ]
 
     def build_prompt(self, context: PromptContext) -> str:

src/daemon/toolchain_handler.py

@@ -13,7 +13,7 @@ from pathlib import Path
 from typing import Dict, List
 
 from src.daemon.base_task_handler import BaseTaskHandler, VerifyResult
-from src.daemon.prompt_composer import PromptComposer, PromptContext
+from src.daemon.prompt_composer import PromptComposer, PromptContext, WikiGuideSection
 from src.daemon.toolchain_templates import render_template, _TEMPLATE_MAP
 from src.blackboard.db import get_connection
 
@@ -226,6 +226,7 @@ class ToolchainHandler(BaseTaskHandler):
             ToolchainContextSection(),
             ToolchainApiSection(),
             ToolchainConstraintsSection(),
+            WikiGuideSection(),
         ]
 
     def build_prompt(self, context: PromptContext) -> str: