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/tjboudreaux/cc-thinking-skills --skill thinking-margin-of-safety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。
リポジトリの原文
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。
Margin of Safety
Core rule: commit a buffered number when residual uncertainty plus breach cost can cause ruin or costly failure. Margin covers estimation error; it is not free slack for laziness.
When to Use
- Capacity, timeouts, pool sizes, queue depths, storage, or SLA numbers under load uncertainty
- Timeline or budget commitments where underestimation is costly
- Architecture headroom when scaling or recovery is slow
- Any public or production commitment where being wrong has asymmetric downside
When NOT to Use
- Breach is detected immediately and fixed near-zero cost (fast auto-scale, live-tunable limit)—static fat buffers waste resources
cost(buffer) > P(breach) × cost(breach)—right-size or measure instead of maxing out- Uncertainty is eliminable by measurement or lookup—get the real number first
- Stopping-criterion / search budget problems—use bounded rationality, not padding
- Fully known parameters and low stakes where edge optimization is the goal
Procedure
- Point estimate without padding. State the base requirement in explicit units (RPS, weeks, GB, ms) and confidence (high / medium / low).
- Uncertainty and breach cost. List drivers (spike, growth, unknowns, dependency variance). State what fails if undershot: outage, missed launch, data loss, reputation—and whether failure is recoverable or ruinous.
- Size the buffer. Multiply or add margin to residual uncertainty and stakes—not to vanity. Typical bands (adjust with evidence):
- Well-known, low consequence: ~1.2–1.5×
- Familiar with unknowns / reversible: ~1.5–2×
- New domain, external deps, SLA, irreversible: ~2–3×
Cap or cut when buffer cost exceeds expected breach cost.
- Ruin constraint. If a breach can cause irreversible harm, size so the worst plausible miss still stays above the failure threshold; if that buffer is unaffordable, change the design (shed load, degrade, stage) rather than pretend precision.
- Strongest countercase. Challenge both under-buffering ("we will scale later") and over-buffering (idle cost, complexity). Prefer measure-then-trim when history exists.
- Commit and monitor. Publish the buffered commitment, the failure threshold, and the metric that would prove margin excessive or thin. Stop when the number is set and monitorable.
Output
text
Base estimate: … (units, confidence)
Uncertainty drivers: …
Breach cost / failure threshold: …
Margin applied: …× (or absolute buffer …)
Buffered commitment: …
Ruin check: pass | redesign needed
Cost of margin vs expected breach cost: …
Monitor: metric … ; thin if … ; excessive if …Verification
- Falsify: If the buffered number equals the optimistic point estimate, no margin was applied—or if margin was added with zero stated breach cost, it is cargo-cult padding.
- Stop: Once commitment, threshold, and monitor exist, stop stacking multipliers without new uncertainty evidence.
- Over-application guard: Do not pad when adjustment is free and instant, or when the real number is cheaply measurable. Do not confuse search-stopping with capacity buffers.
