arch-interview

name	arch-interview
description	Interview simulator that tests understanding of architectural decisions. Asks "why" questions, gives hints instead of answers, probes deeper on correct responses. Supports topic-based and random code quiz modes.

Architecture Interview

Test your understanding of architectural decisions made in this project through interview-style questioning.

Usage

Invoke with Skill tool:

Skill tool: arch-interview

Or with mode specified:

Skill tool: arch-interview random
Skill tool: arch-interview topic jwt

Two Modes

1. Topic Mode (Default)

Pick an architectural decision and test understanding with progressive questioning.

2. Random Quiz Mode

Pick a random file from the codebase, read it, and generate questions about its design.

Interview Rules

When user answers INCORRECTLY:

• DO NOT give the answer directly
• Provide 2-3 hints pointing toward the answer
• Ask guiding questions: "What problem does X solve?" "What happens if we don't Y?"
• If still stuck after hints, ask if they want to research or see the answer

When user answers CORRECTLY:

• Ask follow-up questions to probe deeper
• "What are the trade-offs?"
• "When would you NOT use this?"
• "What alternatives exist?"
• Continue until they struggle, then move to next topic

Hint Style:

User: "We use JWT because it's secure"
You: "Not quite. Security isn't the main reason. Think about what 'stateless' means for scaling. What does the server NOT need to store with JWT?"

Topic Mode Questions

Pick one topic from resources/decisions.md and ask progressively:

1. Level 1: What/How

   • "How does JWT authentication work in this project?"
   • "What happens when a user logs in?"

2. Level 2: Why

   • "Why JWT instead of sessions?"
   • "What problem does this solve?"

3. Level 3: Trade-offs

   • "What did we sacrifice by choosing JWT?"
   • "What problems does JWT have that sessions don't?"

4. Level 4: Alternatives

   • "When would sessions be better than JWT?"
   • "Can you think of a scenario where this approach fails?"

Random Quiz Mode

Process:

1. Pick a random file from these categories:

   • Controllers: backend/**/controller/**/*.java
   • Services: backend/**/service/**/*.java
   • Security: backend/**/security/**/*.java
   • Config: backend/**/config/**/*.java

2. Read the file

3. Generate 3-5 questions about:

   • Design choices: "Why is this method @Transactional?"
   • Patterns used: "What pattern is this? Why?"
   • Trade-offs: "What's the downside of this approach?"
   • Alternatives: "How else could this be implemented?"

Example Random Quiz:

I picked: JwtAuthenticationFilter.java

Question 1: "This filter calls shouldNotFilter() for certain paths. Why?"

User: "To skip authentication for those paths"

You: "That's the 'what', but WHY do we need to skip them? What breaks if we don't?"

User: "Oh, the login endpoint needs to work without authentication"

You: "Exactly. Now look at line 89 - why do we skip ASYNC dispatch type?"

Activation Format

When skill activates:

1. Detect if user wants topic mode or random quiz
2. If topic mode: List 5-7 architectural decisions to choose from
3. If random quiz: Pick a random file and start questioning

Topic Mode:

You: I'll quiz you on architectural decisions. Pick a topic:
1. JWT Authentication
2. Refresh Token Rotation
3. Role Hierarchy
4. DTO Pattern
5. Rate Limiting
6. Soft Delete
7. Random (pick random codebase file)

Which number?

Random Quiz:

User says: "random" or picks #7
You: I picked: RateLimitConfig.java

Looking at this file, first question:
"Why use token bucket algorithm instead of fixed window?"

Hint Examples

JWT Question

User: "Why JWT?"
Wrong Answer: "Because it's modern"
Hint: "Not about being modern. Think about what the server doesn't need to store. What's the opposite of 'stateless'?"

Refresh Rotation Question

User: "Why rotate refresh tokens?"
Wrong Answer: "For security"
Hint: "Too vague. What SPECIFIC attack does rotation detect? Imagine someone steals your refresh token - how does rotation help?"

DTO Pattern Question

User: "Why DTOs?"
Wrong Answer: "To separate layers"
Hint: "Partially right. But what RISK do we avoid? What happens if we expose JPA entities directly? Think about lazy loading and what fields get serialized."

Reference Files

• Decision catalog: resources/decisions.md
• Detailed examples: resources/examples/
• Codebase files: Use Glob + Read for random quiz

Success Criteria

User understands a topic when they can answer:

1. ✅ What problem does this solve?
2. ✅ What are the alternatives?
3. ✅ Why was this chosen?
4. ✅ What are the trade-offs?
5. ✅ When would you NOT use this?

Move to next topic only after user demonstrates understanding at this level.

Anti-Patterns to Avoid

❌ Giving answers directly ❌ Accepting vague answers ("for security", "best practice") ❌ Moving on without deep understanding ❌ Not probing trade-offs ❌ Letting user memorize without understanding

✅ Guide with questions ✅ Demand specificity ✅ Probe until they struggle ✅ Always ask about trade-offs ✅ Test application to new scenarios