Writing Plans

Overview

将 spec/需求拆分为分步实施计划。写清楚每步改哪些文件、代码、测试、怎么验证。DRY. YAGNI. TDD. Frequent commits.

Announce at start: "I'm using the writing-plans skill to create the implementation plan."

Context: Write the plan on main before opening a feature worktree. After the plan is committed, continue to worktree and then tdd.

开工前 Recall（F102 记忆系统）🔴：写计划前先搜相关历史——search_evidence("{feature}") 找相关 spec/ADR/讨论，避免重复造轮子。

Save plans to: feature-specs/YYYY-MM-DD-<feature-name>.md

Straight-Line Check (A→B, No Detour)

Before splitting steps, do this first:

1. Pin the finish line: one-sentence B definition + acceptance criteria + "what we're NOT building"
2. Define terminal schema: interfaces / types / data structures of the final form — steps are built around this, not throwaway scaffolding
3. Every step passes three questions:
   • Will this step's output stay in the final system as-is (extend only, no rewrite)? → Yes = on the line; No = detour
   • What can we demo/test after this step? (no verifiable evidence = detour)
   • If we remove this step, what specific cost does it add to reaching B? (can't articulate = detour)
4. Pure exploration = explicit Spike (time-boxed + output is a decision/conclusion, not a deliverable)

Steps are internal implementation rhythm, NOT delivery batches. The deliverable to the user is a complete feat matching the full spec — not a step's output. Do not expose intermediate steps as "验收点" to the user.

Stateful Object Gate（F229 PR-A1 20 轮教训）🔴

Plan 涉及有生命周期的状态对象（thread 标记 / carrier / session / 持久 config / cache / 索引 / 注册表）时，「功能描述 + 幂等测试点」不够——那是把状态机的边留给 reviewer 逐轮补（PR #2202 实测：4 P1 + 16 P2 全是同一对象的状态转移边——crash window / restore 复活 / deleted-list 漏过滤 / 并发 race / self-heal，打了 20 轮才合入）。

Census 先行（F229 A3a 二次教训 2026-06-11）：gate 第一步是普查——列出 plan 涉及的全部有生命周期对象再逐个三件套。特别注意"复用现有 API"场景下的新消费侧状态（轮询循环、发送闸门、到达判定器都是状态机）。漏报对象 = gate 形同虚设：F229 A3b 三对象三件套齐全，A3a 的 ConversationSendCycle 漏普查 → 云端同型 5 轮逐边补课。

三件套，缺一 = plan 不完整，不准发给实现猫：

1. 状态×事件转移表 — 含「唯一 lifecycle owner 是谁」+「旁路 API（generic restore / delete / list）禁止哪些操作」
2. 不变量清单 — INV-N 编号，每条标注可测方式，test matrix 逐条对应
3. 对抗场景 — crash window / 并发双写 / 恢复路径 / 旁路 API 误用，每个场景一条测试

派生值规则：能用纯投影（pure selector，零存储）表达的状态，禁止落独立存储——无同步即无失同步。

• 范例：(internal reference removed)（球态纯投影 + INV-1~9 + test matrix 即写码顺序）
• 反例：同 feature PR-A1 plan 段（一行"幂等懒创建"→ remote review 20 轮逐边补课）

Bite-Sized Task Granularity

Each step is one action (2-5 minutes):

• "Write the failing test" - step
• "Run it to make sure it fails" - step
• "Implement the minimal code to make the test pass" - step
• "Run the tests and make sure they pass" - step
• "Commit" - step

Plan Document Header

Every plan MUST start with this header:

# [Feature Name] Implementation Plan

**Feature:** F0xx — `docs/features/F0xx-xxx.md`
**Goal:** [One sentence — must match feat doc 的 goal]
**Acceptance Criteria:** [从 feat doc 逐条抄过来，plan 必须覆盖全部 AC]
**Architecture cell:** [ownership cell id from docs/architecture/ownership/README.md]
**Map delta:** none | update required | new cell required
**Map delta why:** [一句话说明为什么不改 map / 改哪个 cell / 为什么需要新 cell]
**Architecture:** [2-3 sentences about approach]
**Tech Stack:** [Key technologies/libraries]
**前端验证:** [涉及前端？标注 Yes — reviewer 必须用 Playwright/Chrome 实测]

---

F191 约束：普通增量写 Map delta: none，不得重新画架构图。update required 或 new cell required 代表 Phase 0 还包含 ownership map 更新，必须在 implementation steps 里列出来。

Task Structure

### Task N: [Component Name]

**Files:**
- Create: `exact/path/to/file.py`
- Modify: `exact/path/to/existing.py:123-145`
- Test: `tests/exact/path/to/test.py`

**Step 1: Write the failing test**

```python
def test_specific_behavior():
    result = function(input)
    assert result == expected

Step 2: Run test to verify it fails

Run: pytest tests/path/test.py::test_name -v Expected: FAIL with "function not defined"

Step 3: Write minimal implementation

def function(input):
    return expected

Step 4: Run test to verify it passes

Run: pytest tests/path/test.py::test_name -v Expected: PASS

Step 5: Commit

git add tests/path/test.py src/path/file.py
git commit -m "feat: add specific feature"

## Open Questions in Plans

计划中的 Open Question 必须分类：
- **技术 OQ**：实现过程中自行解决
- **价值 OQ**：需要 operator 判断 → 附 Decision Packet（格式见 `refs/decision-matrix.md`），包含 TL;DR + 回滚成本 + 真正需要判断的价值问题

先判断可逆性：回滚成本低的不升级 operator，猫猫自决。

## Remember
- Exact file paths always
- Complete code in plan (not "add validation")
- Exact commands with expected output
- DRY, YAGNI, TDD, frequent commits

## 下一步

计划写完并提交 → **直接加载 `worktree`**（创建隔离开发环境）→ `tdd`（开始实现）。SOP 链条自动推进（§17）。