feat(ai): 业务上下文感知与 A2UI 链路统一

- 新增代码内业务上下文元数据层（实体字典 + 三大闭环工作流）
- 新增 get_business_context / get_entity_schema / get_pending_tasks 运行时工具
- SYSTEM_PROMPT 与技能目录改为先查业务流程/待办再执行
- A2UI 增加 ai_a2ui_submissions 幂等表、表单过期、ui.artifact 事件
- 提交回灌携带 submissionId / fieldErrors / 下一步建议
- 前端 uiArtifacts 归一化与过期表单禁用

apps/server/src/agent-context/get-business-context.tool.ts

@@ -0,0 +1,90 @@
+import { Injectable } from '@nestjs/common';
+import type { AgentToolContext, ToolDef, ToolInputResult } from '../agent-tools/agent-tool.types';
+import { rejectUnknownKeys, optionalString } from '../agent-tools/tools/tool-input';
+import type { BusinessContextService } from './business-context.service';
+
+interface GetBusinessContextInput {
+  workflowKey?: string;
+}
+
+/**
+ * 让 Agent 获取当前角色可见的业务流程、实体字典与依赖规则。
+ */
+@Injectable()
+export class GetBusinessContextTool implements ToolDef<GetBusinessContextInput> {
+  readonly name = 'get_business_context';
+  readonly skillKey = 'assistant';
+  readonly requiredPermission = 'ai:chat:use';
+  readonly description =
+    '获取当前账号可见的业务流程（学生教学/住宿计费/教室租赁）、实体字典、阶段依赖与下一步建议。写入或导入前先调用本工具确认前置数据要求。';
+  readonly inputSchema = {
+    type: 'object',
+    properties: {
+      workflowKey: {
+        type: 'string',
+        description: '可选：聚焦某个闭环（student_teaching / dormitory_billing / classroom_rental）',
+        maxLength: 50,
+      },
+    },
+    additionalProperties: false,
+  };
+
+  constructor(private readonly service: BusinessContextService) {}
+
+  validate(input: Record<string, unknown>): ToolInputResult<GetBusinessContextInput> {
+    const invalid = rejectUnknownKeys(input, ['workflowKey']);
+    if (invalid) return invalid;
+    const workflowKey = optionalString(input.workflowKey, 'workflowKey', 50);
+    if (!workflowKey.ok) return workflowKey;
+    return { ok: true, value: { workflowKey: workflowKey.value } };
+  }
+
+  async execute(input: GetBusinessContextInput, context: AgentToolContext): Promise<unknown> {
+    return this.service.getBusinessContext(
+      { permissions: context.permissions, isSuperAdmin: context.isSuperAdmin },
+      input.workflowKey,
+    );
+  }
+}
+
+/**
+ * 让 Agent 获取指定业务实体的字段字典与关系，用于生成准确表单。
+ */
+@Injectable()
+export class GetEntitySchemaTool implements ToolDef<{ entityKey: string }> {
+  readonly name = 'get_entity_schema';
+  readonly skillKey = 'assistant';
+  readonly requiredPermission = 'ai:chat:use';
+  readonly description =
+    '获取指定业务实体（student/class/room/occupancy/expense/bill/deposit/classroom/organization/rental 等）的字段字典、枚举来源与关系，render_form 前可按需调用以生成正确字段。';
+  readonly inputSchema = {
+    type: 'object',
+    properties: {
+      entityKey: { type: 'string', minLength: 1, maxLength: 50 },
+    },
+    required: ['entityKey'],
+    additionalProperties: false,
+  };
+
+  constructor(private readonly service: BusinessContextService) {}
+
+  validate(input: Record<string, unknown>): ToolInputResult<{ entityKey: string }> {
+    const invalid = rejectUnknownKeys(input, ['entityKey']);
+    if (invalid) return invalid;
+    if (typeof input.entityKey !== 'string' || !input.entityKey.trim()) {
+      return { ok: false, error: 'entityKey 必须是字符串' };
+    }
+    const entityKey = input.entityKey.trim();
+    if (entityKey.length > 50) {
+      return { ok: false, error: 'entityKey 长度不能超过 50' };
+    }
+    return { ok: true, value: { entityKey } };
+  }
+
+  async execute(input: { entityKey: string }, context: AgentToolContext): Promise<unknown> {
+    return this.service.getEntitySchema(
+      { permissions: context.permissions, isSuperAdmin: context.isSuperAdmin },
+      input.entityKey,
+    );
+  }
+}