Author orch Markdown test plan

docs/tests/orch/council-start/README.md

@@ -1,7 +1,7 @@
 # Orch `council start` Test Plan Index
 
-## Status
+## Case Files
 
-No command case files are authored yet.
-
-Use [../ROADMAP.md](../ROADMAP.md) for planned case slugs and document progress.
+| Case Slug | File | Coverage Note |
+| --- | --- | --- |
+| `council-start-dispatches-three-reviewers` | [council-start-dispatches-three-reviewers.md](./council-start-dispatches-three-reviewers.md) | creates the council run, dispatches the fixed three reviewer roles, and exposes the expected default metadata |

docs/tests/orch/council-start/council-start-dispatches-three-reviewers.md

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+# Case: `council-start-dispatches-three-reviewers`
+
+## 用例意义
+
+验证 `council start` 会创建一个新的 council run，并立即分派固定的三位 reviewer：`architecture-reviewer`、`implementation-reviewer`、`risk-reviewer`。
+
+## 前置条件
+
+- 使用隔离的临时目录 `TMPDIR`
+- 目标数据库 `TMPDIR/coord.db` 尚不存在
+
+## 输入
+
+```bash
+orch --db TMPDIR/coord.db --json council start \
+  --run council_blog_001 \
+  --target "Review the current blog architecture and propose optimizations." \
+  --target-type mixed \
+  --output both
+
+orch --db TMPDIR/coord.db --json status --run council_blog_001
+```
+
+## 预期输出
+
+- `council start` 退出码为 `0`
+- `start.data.run_id == "council_blog_001"`
+- `start.data.mode == "brainstorm"`
+- `start.data.target_type == "mixed"`
+- `start.data.output == "both"`
+- `start.data.only_unanimous == false`
+- `start.data.reviewers` 长度为 `3`
+- 三个 reviewer 的 `reviewer_role` 分别为 `architecture-reviewer`、`implementation-reviewer`、`risk-reviewer`
+- 三个 reviewer 的 `status` 都是 `dispatched`
+- 后续 `status` 返回 `3` 个 task，run 处于活动中而不是终态
+
+## 断言结论
+
+- `council start` 不只是创建 run 元数据，还会直接完成 reviewer task 的创建与分派
+- v1 reviewer 集合是固定的三角色集合，而不是由用户动态指定
+
+## 补充约束
+
+- 未显式传入 `--mode` 时，默认回退到 `brainstorm`
+- 未显式传入 `--only-unanimous` 时，默认值是 `false`
+- council reviewer task 在当前实现里不应自动申请 code worktree