常见校验修复（TOON 独立文件 spec）：

1) 缺少校验作用域（`Spec valid_scope must not be empty`）：
Main spec 必须在 `.toon` 文档内携带非空的 `valid_scope`。
`llmanspec/specs/<feature-id>/spec.toon`：
```toon
kind: llman.sdd.spec
name: sample
purpose: "One-line overview."
valid_scope[1]: src
requirements[1]{req_id,title,statement}:
  r1,Title,System MUST do something.
scenarios[1]{req_id,id,given,when,then}:
  r1,happy,"",a trigger happens,the outcome is observed
```

2) Change 缺少 delta ops：至少补一个 op + scenario（`llmanspec/changes/<change-id>/specs/<feature-id>/spec.toon`）：
```toon
kind: llman.sdd.delta
ops[1]{op,req_id,title,statement,from,to,name}:
  add_requirement,r1,Title,System MUST do something.,null,null,null
op_scenarios[1]{req_id,id,given,when,then}:
  r1,happy,"",a trigger happens,the outcome is observed
```

3) 表格化行引号错误（"Expected N tabular row values, but got M"）：
值包含**空格**、逗号、冒号或方括号时，必须用双引号包裹。
```toon
# 错误：未加引号的空格值会被拆成多个值
r1,happy,"",a trigger happens,the outcome is observed

# 正确：多词值加引号
r1,happy,"","a trigger happens","the outcome is observed"
```

4) BDD 空 spec 护栏（`BDD is enabled but this spec declares no requirements and no feature_refs`）：
当 `config.yaml` 含 `bdd` 块时，spec 必须要么声明 `requirements`，要么通过 `feature_refs` 指向 `.feature`（point-only 模式）。

备注：
- 每个 spec 是一个独立的 `.toon` 文件；没有 Markdown 外壳，也没有 ```toon fence。
- `null` 表示可选字段缺失。
- 从旧版 `.md`+fence 迁移请使用 `llman sdd migrate`。
