## ADDED Requirements

### Requirement: Inventory statistics and analysis

The system SHALL provide 盘存统计分析 functions over inventory and plan-related quantities, constrained by `pl_` inventory model definitions delivered in milestone M2 or later.

#### Scenario: Authorized user runs report

- **WHEN** an authorized user requests the standard inventory statistics report for a closed period
- **THEN** the system SHALL return aggregated metrics consistent with underlying `pl_` stock movements for that period

#### Scenario: Unauthorized access denied

- **WHEN** a user without report permission requests the same report
- **THEN** the system SHALL deny access