function-descriptionlisted

# Function Description ## Purpose And Boundary Define HOW every in-scope feature behaves — at a level business can understand, development can implement, and testing can verify. This Skill owns the feature inventory (FEA), functional flow, and domain rules (BR, VL, state, exceptions, AC). Interaction rules (IX) are owned by product-ux/interaction-rules — **reference them, do not redefine them**. **Do not**: redesign UX, add untraceable features, write test cases, architecture, database schemas, or API contracts. ## Sub-Skills (execution order) Each produces a section of the function-description artifact: 1. `feature-list` → §功能清单 (FEA table: confirmed in-scope feature inventory) 2. `functional-flow` → §功能流程 (per-FUN main/alternate/exception/failure paths) 3. `business-rules` → §业务规则 (BR table: domain constraints, calculations, policies) 4. `validation-rules` → §校验规则与字段定义 (VL table: field-level + cross-field checks, error messages + field definitions) 5. `state-machine` → §状态变化 (STATE table: states × events → target states) 6. `exception-handling` → §异常处理 (EX table: failure modes + user-visible recovery) 7. `acceptance-criteria` → §验收依据 (AC table: Given/When/Then + quantified thresholds) ## Inputs And Outputs **Input**: 上游功能清单 FEA（`feature-list` 子 skill 产出）+ confirmed `product-ux` (IX, pages) + confirmed business upstream (ST, scope baseline). **Output**: 一个 `function-description.md`，由 7 个子 skill 依次产出 7 个章节：§功能清单 / §功能流程 / §业务规则 / §校验规则与字段定义 / §状态变化 / §异常处理 / §验收依据。字段规则