Claude Code in Action

• QuestionWhat is "Order all hook lifecycle events"?Tap to revealAnswerPer turn: SessionStart → UserPromptSubmit → PreToolUse → tool → PostToolUse → ... → Stop → SessionEnd. PreToolUse / PostToolUse fire per *tool call*; Stop fires per *task*.
• QuestionIn "Order all hook lifecycle events", explain:Tap to revealAnswerPer-turn order: SessionStart → UserPromptSubmit → PreToolUse → [tool] → PostToolUse → ... → Stop → SessionEnd.
• QuestionIn "Order all hook lifecycle events", explain:Tap to revealAnswerPreToolUse / PostToolUse: per individual tool call.
• QuestionIn "Order all hook lifecycle events", explain:Tap to revealAnswerUserPromptSubmit: per user turn (before tool calls).
• QuestionIn "Order all hook lifecycle events", explain:Tap to revealAnswerStop: per task / turn (once).
• QuestionAnalogy for "Order all hook lifecycle events":Tap to revealAnswerThink of a meal: opening (SessionStart) → request order (UserPromptSubmit) → before each dish (PreToolUse) → the dish (tool) → after each dish (PostToolUse) → end of meal (Stop) → close the restaurant (SessionEnd). 'After each dish' ≠ 'after the meal.'
• QuestionWhat is "Hook vs CLAUDE.md by trust level"?Tap to revealAnswerUse a hook when you can't tolerate the model ignoring the rule. Use CLAUDE.md when 'usually applies' is good enough.
• QuestionIn "Hook vs CLAUDE.md by trust level", explain:Tap to revealAnswerSingle decision axis: trust requirement.
• QuestionIn "Hook vs CLAUDE.md by trust level", explain:Tap to revealAnswerCannot accept model override → hook.
• QuestionIn "Hook vs CLAUDE.md by trust level", explain:Tap to revealAnswerAdvice / nudge / preference → CLAUDE.md.
• QuestionIn "Hook vs CLAUDE.md by trust level", explain:Tap to revealAnswerHooks have synchronous determinism + event context + block primitive.
• QuestionAnalogy for "Hook vs CLAUDE.md by trust level":Tap to revealAnswerIt's like the difference between an office handbook (CLAUDE.md — read, expected to follow) and a locked door (hook — physically enforced).
• QuestionWhat is "Predict no-watermark loop failure"?Tap to revealAnswerLong-running agents need budget watermarks: at 80% commit and exit cleanly, at 95% hard exit. No watermark = clipped final output and lost progress.
• QuestionIn "Predict no-watermark loop failure", explain:Tap to revealAnswerNo watermark = runaway loop = clipped output / lost context.
• QuestionIn "Predict no-watermark loop failure", explain:Tap to revealAnswerTwo watermarks: 80% (soft, commit + exit cleanly), 95% (hard exit).
• QuestionIn "Predict no-watermark loop failure", explain:Tap to revealAnswerWatermarks live at the loop / harness layer, not in prompts.
• QuestionIn "Predict no-watermark loop failure", explain:Tap to revealAnswer'Exit cleanly' is success — partial work committed and recoverable.
• QuestionAnalogy for "Predict no-watermark loop failure":Tap to revealAnswerIt's like running a marathon with no concept of pacing. You sprint, then collapse mid-track — instead of slowing down at mile 20 (80%) to finish the last 6 properly.
• QuestionWhat is "Subagent vs inline"?Tap to revealAnswerSpawn a subagent only when work is genuinely parallel or its intermediate context would pollute the parent. Otherwise, inline.
• QuestionIn "Subagent vs inline", explain:Tap to revealAnswerTwo and only two triggers: parallelism, isolation.
• QuestionIn "Subagent vs inline", explain:Tap to revealAnswerParallelism: independent work the parent can fan out.
• QuestionIn "Subagent vs inline", explain:Tap to revealAnswerIsolation: intermediate context that shouldn't pollute the parent.
• QuestionIn "Subagent vs inline", explain:Tap to revealAnswerCost, window-size, tool-count are NOT triggers (and are common distractors).
• QuestionAnalogy for "Subagent vs inline":Tap to revealAnswerLike delegating to a teammate: do it when you can run two efforts in parallel or when you don't want their messy scratch on your desk. Don't delegate just to feel organised.
• QuestionWhat is "CI surface blast radius"?Tap to revealAnswerClaude Code in CI runs with the same permissions as a developer with the same token. CI's higher autonomy means damage potential is higher, not lower.
• QuestionIn "CI surface blast radius", explain:Tap to revealAnswerCI = same permissions as a dev with the equivalent token. No new boundary.
• QuestionIn "CI surface blast radius", explain:Tap to revealAnswerRepo secrets, registry tokens, cloud creds — all in scope for the agent.
• QuestionIn "CI surface blast radius", explain:Tap to revealAnswerHooks that protect local surface should also be present (or stronger) in CI.
• QuestionIn "CI surface blast radius", explain:Tap to revealAnswerCI's higher autonomy raises the ceiling on damage, not lowers it.
• QuestionAnalogy for "CI surface blast radius":Tap to revealAnswerThink of CI as a developer working unsupervised. They have all the keys; nobody's watching the screen. Either keep the key set small or put locks on the dangerous doors (hooks).

1. 1List the core idea

   Analyse~10 min

   In your own words, list the central idea of "Order all hook lifecycle events". Aim for one paragraph, no jargon you haven't earned.

   Done when: A non-expert could read your paragraph and explain it back to you.

   Re-read the source concept

2. 2Use it to a real situation

   Apply~15 min

   Find a real situation from your own work / life where "CI surface blast radius" applies. Use the idea — describe the situation, the move you'd make, and the alternative you considered first.

   Done when: You can name a specific situation (not a hypothetical), state your move, and explain the trade-off in one paragraph.

   Re-read the source concept

3. 3Teach it back

   Evaluate~5 min

   Pick someone (a colleague, a peer, a rubber duck) and explain the section to them in under 5 minutes. Use your own example, not the one from the lesson.

   Done when: Your listener can repeat the core idea + the trade-off back to you without prompting.

Why this matters. Reading + quizzing prove recall; applying it in a real situation is the only evidence of transfer. Treat at least one of these as non-negotiable before you move on.