A phase is a chunk of work inside a session: the grilling, the implementation, the QA. The definition is fuzzy on purpose: a phase ends when you think "ok, we're done with that".
phase（階段） 是 session 內的一塊工作——grilling、實作、QA。這個定義是刻意模糊的：當你心想「好，我們搞定這個了」時，階段就結束了。
The phase boundary is the gap between two phases, and it is the only place this decision belongs. Mid-phase there is no decision to make: continue, or split the work that's left into subagents. Compacting mid-phase makes the agent lose the thread.
階段邊界是兩個階段之間的間隙，也是這個決策唯一歸屬的地方。在階段中途沒有要做的決策——繼續，或把剩餘的工作拆給子代理。在階段中途 compact 會讓代理失去頭緒。
| Option | What it does |
|---|---|
| Continue | Stay in the session. No context switch at all. |
/clear |
Empty the context window and start from nothing. |
/handoff |
Write a portable markdown file and seed a session anywhere with it. |
| Subagent | Send the task to its own context window and get a report back. |
/compact |
Compress this context and seed a fresh session with the summary. |
| Option（選項） | 作用 |
|---|---|
| Continue（繼續） | 留在 session 中。完全不做上下文切換。 |
/clear |
清空上下文視窗，從零開始。 |
/handoff |
寫一個可攜帶的 markdown 檔案，並用它孕育出任何地方的 session。 |
| Subagent（子代理） | 把任務送到它自己的上下文視窗，並拿回一份報告。 |
/compact |
壓縮這個上下文，並以摘要孕育出一個新的 session。 |
Work top to bottom at the boundary. The first yes wins.
在邊界上從上到下逐一檢視。第一個「是」勝出。
1. Can you continue in this session? Two things make the answer yes: the next phase needs this phase as a primary source, or you have enough smart zone left (~150k tokens) for the next phase to fit. Grilling → implementation is the standard yes: the implementation wants the reasoning verbatim, not a summary of it. Continue costs nothing and loses nothing, so rule it out before anything else.
1. 你能在這次 session 中繼續嗎？ 有兩件事會讓答案為「是」：下一個階段需要把這個階段當作主要來源，或者你還有足夠的智慧區（約 150k tokens）容納下一個階段。Grilling → 實作是標準的「是」：實作要的是逐字的推理，而不是它的摘要。Continue（繼續）不花任何成本，也不失去任何東西，所以要先排除其他一切選項。
2. Is the context irrelevant to what comes next? Is everything in this session (the exploration, the decisions, the dead ends) disposable? If so, /clear. It is the cheapest move on the board: it takes no time and hands back the whole window. /clear also isn't terminal: the old session stays resumable.
2. 這個上下文跟接下來要做的事無關嗎？ 這次 session 中的一切——探索、決策、死路——都可丟棄嗎？如果是，/clear。這是棋盤上最便宜的招法：不花時間，並把整個視窗還給你。/clear 也不是終點——舊的 session 仍可恢復。
The cost of getting this wrong is one-way. Clear a relevant context and you lose the why behind what you built, and no amount of reading the diff back gets it returned.
搞錯這個的成本是單向的。清掉相關的上下文，你就失去建置背後的那個「為什麼」，而無論你回頭讀多少次 diff，都找不回來。
3. Do you need to hand off? /handoff is narrow. You need it only when you are:
3. 你需要 hand off（交接）嗎？ /handoff 的範圍很窄。只有在以下情況你才需要它：
That list is the whole clause. What /handoff buys is portability: a file that travels. If nothing is travelling, you don't need it.
這份清單就是全部的條件。/handoff 買到的是可攜帶性——一個可以帶著走的檔案。如果沒有東西在移動，你就不需要它。
4. Can the task be done AFK? Is it scoped tightly enough to run with you away from the keyboard, no steering? Then send it to a subagent and leave this session untouched. Automated review is the standard case: the agent reads the diff and reports, and you aren't needed while it does.
4. 這個任務可以 AFK 完成嗎？ 它的範圍是否緊密到可以讓你在離開鍵盤、不做任何操控的情況下運行？如果是，把它交給子代理，並讓這次 session 保持原樣。自動化審查是標準案例：代理讀取 diff 並回報，過程中不需要你。
5. Otherwise, /compact. Relevant context, same harness, same directory, and you need to stay in the loop: this is where the tree lands, and it lands here often. Pass it an instruction (/compact we're going to QA this area) so the summary keeps what the next phase needs.
5. 否則，/compact。 上下文相關、執行環境相同、目錄相同，而你必須留在迴圈中——決策樹最後會落在這裡，而且經常如此。給它一個指令（/compact we're going to QA this area），讓摘要保留下一個階段需要的內容。
/compact is the default, not the first reach. It sits at the bottom because the four questions above it are all cheaper or more precise. The failure mode when people start here is a fresh session that is confidently wrong about a decision the summary flattened.
/compact 是預設選項，而不是第一個伸手去拿的。它位於底部，因為它上面的四個問題都更便宜或更精確。當人們從這裡開始時的失敗模式是：一個新的 session 對摘要所碾平的那個決策，充滿信心地犯錯。
Every move except Continue turns a primary source into a secondary source: the session as it happened, replaced by a summary of it. The trade is always the same shape:
除了 Continue（繼續） 之外，每個動作都會把主要來源變成次要來源——原本發生的 session，被它的摘要取代。這個取捨的形狀始終相同：
| Source | Information | Noise | Room to move |
|---|---|---|---|
| Primary (Continue) | Full | Lots | Little |
Secondary (/compact, /handoff) |
Lossy | Less | Lots |
| 來源 | 資訊 | 雜訊 | 活動空間 |
|---|---|---|---|
| 主要（Continue／繼續） | 完整 | 多 | 小 |
次要（/compact、/handoff） |
有損 | 少 | 大 |
This is why question 1 comes first. You only pay the lossiness when staying costs more than it saves.
這就是為什麼問題 1 要放最前面。只有當留下來耗費的成本超過它所省下的時，你才需要付出有損的代價。
The questions are not objective: each has taste in it, and the same boundary can go two ways on two days. The value is in asking them in order, at the boundary rather than in the middle of the work.
這些問題不是客觀的——每個都含有品味，而且同一個邊界在不同日子可能會有不同的答案。價值在於依序提出它們，在邊界上而非工作中途提出。