feat: add streaming learning assistant and knowledge base scaffolding

app/services/knowledge_space_service.py

@@ -0,0 +1,39 @@
+from app.core.context import UserContext
+from app.core.exceptions import AppError
+from app.models.knowledge_base import KbKnowledgeSpace
+from app.repositories.knowledge_base_repository import KnowledgeBaseRepository
+
+
+class KnowledgeSpaceService:
+    """知识空间服务：按用户所属机构定位知识库 collection。"""
+
+    def __init__(self, repo: KnowledgeBaseRepository) -> None:
+        self.repo = repo
+
+    def require_institution_id(self, ctx: UserContext) -> int:
+        """机构校验：知识库能力必须绑定 Django 用户中心返回的 institution_id。"""
+        if ctx.institution_id is None:
+            raise AppError("INSTITUTION_REQUIRED", "institution_id is required for knowledge base", 403)
+        return int(ctx.institution_id)
+
+    def get_or_create_space(self, ctx: UserContext) -> KbKnowledgeSpace:
+        """知识空间获取：内容管理员上传文档时自动创建机构知识空间。"""
+        institution_id = self.require_institution_id(ctx)
+        profile = ctx.profile or {}
+        institution_name = profile.get("institution_name") or f"institution_{institution_id}"
+        return self.repo.get_or_create_space(institution_id, institution_name)
+
+    def get_active_space(self, ctx: UserContext) -> KbKnowledgeSpace:
+        """知识空间读取：AI 学习助手问答时读取机构当前可用知识空间。"""
+        institution_id = self.require_institution_id(ctx)
+        space = self.repo.get_space(institution_id)
+        if not space:
+            raise AppError("KNOWLEDGE_SPACE_NOT_FOUND", "knowledge space not initialized for institution", 404)
+        return space
+
+    def ensure_content_admin(self, ctx: UserContext) -> None:
+        """权限校验：仅内容管理员或系统管理员可以上传并构建机构知识库。"""
+        role = (ctx.role or "").lower()
+        allowed_roles = {"content_admin", "institution_admin", "admin", "super_admin"}
+        if role not in allowed_roles:
+            raise AppError("KNOWLEDGE_ADMIN_FORBIDDEN", "only content admin can upload knowledge documents", 403)