Interview Index: 22 chapters × 10 questions = 220 deep questions
§1 · How to use this index
Section titled “§1 · How to use this index”Four ways to use this page:
- By chapter order: read §1 to §22 in order. 10 questions per chapter, later chapters go deeper.
- By topic cross-cut: use the topic quick-find table to see the same question class from different angles.
- As an interview question bank: every link in this index goes straight to a chapter’s §11. Copy-paste ready.
- As a self-checklist: when building your own agent, find the chapter matching the design choice ahead, then audit the decision against those 10 questions.
§2 · Group 1 · Agent Fundamentals (5 chapters × 10 questions = 50)
Section titled “§2 · Group 1 · Agent Fundamentals (5 chapters × 10 questions = 50)”Themes: harness definition, agent loop, context, tool, verifier. These 50 cover the vocabulary and trade-offs of agent fundamentals.
| Chapter | Topic | Link |
|---|---|---|
| §1 | Agent Harness definition, concept boundaries, picking among the four systems | 01 · Overview |
| §2 | Agent loop five phases (perceive / plan / act / observe / verify), turn data structure, prompt assembly, context compaction, error recovery, tool dispatch, verifier | 02 · Agent Loop |
| §3 | Context systems: full spectrum from markdown to 10-layer assembly; how prefix cache holds up | 03 · Context system |
| §4 | Tool system: protocol, registration, parallelism, security gating | 04 · Tool system |
| §5 | Verifier: hard / soft / give-up tiers + stop detection | 05 · Verifier |
§3 · Group 2 · Coding Agent Engineering (4 chapters × 10 questions = 40)
Section titled “§3 · Group 2 · Coding Agent Engineering (4 chapters × 10 questions = 40)”Themes: real coding-agent engineering details. Patch algorithm, shell invocation, git workflow, code review automation. These tell you what extra trouble a coding agent has over a chat agent.
| Chapter | Topic | Link |
|---|---|---|
| §6 | File edit + patch algorithm: apply_patch V4A multi-version diff merge | 06 · File edit patch |
| §7 | Shell execution: execpolicy / sandbox / approval mode | 07 · Shell execution |
| §8 | Git workflow: worktree / branch / commit automation | 08 · Git workflow |
| §9 | Code review: /security-review + LLM-as-reviewer pattern | 09 · Code review |
§4 · Group 3 · Concurrency & Runtime (5 chapters × 10 questions = 50)
Section titled “§4 · Group 3 · Concurrency & Runtime (5 chapters × 10 questions = 50)”Themes: subagent, session lifecycle, permissions, sandbox, multi-channel entry. These 50 are the engineering foundation for keeping the agent stable in production.
| Chapter | Topic | Link |
|---|---|---|
| §10 | Subagent: fork / inline boundary, context isolation | 10 · Subagent |
| §11 | Session lifecycle: start / resume / interrupt / persist | 11 · Session lifecycle |
| §12 | Permissions and approvals: AskForApproval 4 levels + autoMode rules + INSTALL_POLICY 12-cell matrix | 12 · Permissions |
| §13 | Sandbox execution: macOS seatbelt / Linux bwrap+seccomp+landlock / Windows | 13 · Sandbox execution |
| §14 | Multi-channel entry: CLI / TUI / IDE / web / cron | 14 · Multi-channel entry |
§5 · Group 4 · Evolution & Safety (8 chapters × 10 questions = 80)
Section titled “§5 · Group 4 · Evolution & Safety (8 chapters × 10 questions = 80)”Themes: observability, memory, skills, scheduled tasks, self-improvement, security, todo lists, execution-state surfaces. These 80 are the core for long-running agents that stay recoverable and safe.
| Chapter | Topic | Link |
|---|---|---|
| §15 | Observability and cost: token / latency / tool.loop detection | 15 · Observability and cost |
| §16 | Memory system: 4 MemoryTypes, frozen snapshot, decay, prefix cache | 16 · Memory |
| §17 | Skill system: 8 crates / skillify / skill-scanner / 12-cell trust matrix | 17 · Skills |
| §18 | Cron and background tasks: tick + scheduler lock + isolated-agent | 18 · Cron background tasks |
| §19 | Self-improvement: Phase1+2 / skillify / passive indexing / in-turn explicit writes | 19 · Self-improvement |
| §20 | Security: sandbox / external-content / redact / cosign provenance | 20 · Security |
| §21 | Todo List: update_plan / TodoWrite / runtime progress / compaction recovery | 21 · Todo List |
| §22 | Execution State Surfaces: Plan / Todo / tool progress / task progress / terminal status / away summary routing | 22 · Execution State Surfaces |
§6 · Topic quick-find (220 questions cross-cut by type)
Section titled “§6 · Topic quick-find (220 questions cross-cut by type)”The 220 questions can be re-sliced by problem type. The same engineering question shows up at different angles in different chapters. Read horizontally for the fastest understanding.
6.1 Definition / boundary
Section titled “6.1 Definition / boundary”Aligning vocabulary across the four systems. Common in “what’s the difference between A and B” or “why this split”.
| Source | Question |
|---|---|
| §1 Q1 | Agent Harness vs Agent model |
| §2 Q1 | Is “turn” a physical or logical unit |
| §4 Q1 | Tool / Function / Skill boundary |
| §10 Q1 | Subagent / fork / inline distinction |
| §17 Q1 | Skill / prompt template / tool / agent boundary |
| §18 Q1 | Cron job / background task / long-running task differences |
| §21 Q1 | Todo list vs Plan Mode boundary |
| §22 Q1 | Execution-state surface vs todo-list boundary |
6.2 Trade-offs
Section titled “6.2 Trade-offs”Why not B, with concrete context. Common in “why did Codex use X while Hermes used Y.”
| Source | Question |
|---|---|
| §2 Q4 / §3 Q6 | When to use prefix cache vs recompute |
| §11 Q3 | Whether session persistence needs versioning |
| §13 Q5 | Why sandbox doesn’t ban all network |
| §15 Q4 | How observability data avoids exploding disk |
| §16 Q5 | Memory limit in tokens vs chars |
| §18 Q3 | Cron failure auto-disable vs retry |
| §19 Q3 | OpenClaw halfLifeDays=30 derivation |
| §20 Q3 | fail_open vs fail_closed |
| §21 Q6 | Lightweight TodoWrite vs file-backed Tasks |
| §22 Q6 | Why progress display needs per-platform settings |
6.3 Implementation detail
Section titled “6.3 Implementation detail”Concrete APIs, data structures, source pointers. Common in “why does this code do that” / “how does it handle X at runtime.”
| Source | Question |
|---|---|
| §2 Q7 / §6 Q4 | apply_patch V4A multi-version diff merge |
| §3 Q8 | Hermes 10-layer prompt assembly ordering |
| §4 Q6 | dispatchToolUseBlocks parallel dispatch implementation |
| §5 Q5 | Codex goals.rs convergence judgment |
| §12 Q4 | AskForApproval 4 levels mapping to UI |
| §16 Q8 | Hermes _file_lock fcntl/msvcrt cross-platform |
| §17 Q6 | Hermes 12-cell INSTALL_POLICY calculation |
| §20 Q1 | OpenClaw random 8-byte ID wrapping |
| §21 Q8 | Todo replace vs merge API trade-off |
| §22 Q3 | MCP progress vs tool result protocol boundary |
6.4 Security
Section titled “6.4 Security”Injection / poisoning / secrets / supply chain. Common in “how does this attack get defended” / “why design it this way.”
| Source | Question |
|---|---|
| §12 Q9 | Keeping user password out of prompt |
| §13 Q7 | Common sandbox-escape paths |
| §17 Q7 | OpenClaw skill-scanner 3 severities |
| §19 Q5 | Hermes reasoning for blocking invisible unicode |
| §19 Q10 | 6-layer security defense stack |
| §20 Q1 | external-content random ID forgery prevention |
| §20 Q2 | tirith exit code as source of truth |
| §20 Q5 | Codex memory prompt explicit “treat as data” |
| §20 Q10 | 5-layer general security defense |
| §21 Q9 | Why todo completion needs verification nudges |
| §22 Q8 | Why progress surfaces still need no-progress detectors |
6.5 Engineering practice
Section titled “6.5 Engineering practice”How to actually build your agent. Common in “what’s the minimum production needs” / “what’s the minimum viable implementation.”
| Source | Question |
|---|---|
| §1 Q9 | Scenarios where heavy harness is wrong |
| §5 Q10 | 5 iron rules for verifier design |
| §10 Q10 | General subagent design checklist |
| §15 Q10 | General observability framework |
| §16 Q10 | General 5-layer memory architecture |
| §17 Q10 | General 6-layer skill system |
| §18 Q10 | General 7-layer cron system |
| §19 Q10 | General 6-layer self-improvement defense |
| §20 Q10 | General 5-layer security defense |
| §21 Q10 | Minimum 5-layer todo/progress surface |
| §22 Q10 | Minimum execution-state router fields |
§7 · What’s next
Section titled “§7 · What’s next”After 220 questions, the next step is turning insight into reusable engineering capability. Two paths:
- Build directly: pick a chapter’s §7 build recipe, follow the steps to ship a minimum-viable version.
- Crystallize into a skill: use the companion
~/.claude/skills/build-your-own-agent/skill to invoke the best practices distilled from these 220 questions on demand. See the<BuildRecipe />block at the end of each chapter.