使い方
- インストールコマンドをコピーし、自分の環境へ導入する前にソースを確認します。
- 必要なツール、認証情報、対応環境を原文で確認します。
- 入力と成果物を指定し、出力を資料と照合します。
npx skills add https://github.com/mariusflorescu/pstack-t3 --skill principle-make-operations-idempotent開始前の確認
- 導入にはモデル契約、API枠、ファイルへのアクセス許可は含まれません。
- スター数や導入数は活動の指標であり、独立した品質・安全性試験ではありません。
見出し、例、コード、表、リンク、参照画像を含む原文を表示しています。
Make Operations Idempotent
Design operations so they converge to the correct state regardless of how many times they run or where the previous run stopped. Every state-mutating operation should answer: "What happens if this runs twice? What happens if the previous run crashed halfway?"
Why: Commands, lifecycle operations, and processing loops run where crashes, restarts, and retries are normal. If partial state changes the next run's outcome, every restart becomes a debugging session.
The idea: derive each step from the state that exists, not from what the previous run meant to do. Read the current state, compare it to the goal, and apply only the difference. A step written this way is safe to repeat, because a repeat finds nothing left to do.
Anything a run leaves behind, such as a lock, a temporary file, a half-written record, or a claimed job, must be recognizable as stale by the next run. Judge staleness by evidence that stays true wherever the previous run could have stopped, not only in the common case. A marker that the next run cannot judge turns every crash into manual cleanup. For example, write to a temporary path and rename it into place, or compare artifacts by content instead of by creation order.
The test:
- What happens if this runs twice in a row?
- What happens if the previous run crashed at every possible point?
- Does re-execution converge to the same end state?
If any answer is "it depends on what state was left behind," the operation needs a reconciliation step.
