message-queues-interviewer

message-queues-interviewer is a skill for Claude Code, Codex from PrepLabsAI/InterviewMentor. It costs 68 tokens per session (2,123 once invoked), scanned A, original, MIT.

A practice interviewer for designing systems that process messages asynchronously. It focuses on tools such as RabbitMQ and Kafka, which let services exchange work or events without responding at the same time.

In plain words
What is it for?
Use it to practise explaining brokers versus event streams, at-least-once delivery, dead-letter queues for unprocessable messages, and what happens when a consumer crashes mid-processing.
Why use it?
It exposes gaps in your understanding of delivery guarantees, failures, retries, and message processing before a real system-design interview.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/preplabsai/interviewmentor/message-queues-interviewer
Any agent
npx skills add PrepLabsAI/InterviewMentor --skill message-queues-interviewer
Clone the repo
git clone --depth 1 https://github.com/PrepLabsAI/InterviewMentor

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for message-queues-interviewer

README.md
[![agentmods](https://agentmods.dev/badge/skills/preplabsai/interviewmentor/message-queues-interviewer.svg)](https://agentmods.dev/skills/preplabsai/interviewmentor/message-queues-interviewer)
Your own site
<a href="https://agentmods.dev/skills/preplabsai/interviewmentor/message-queues-interviewer"><img src="https://agentmods.dev/badge/skills/preplabsai/interviewmentor/message-queues-interviewer.svg" alt="Measured on agentmods" height="20"></a>
Per session 68 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,123 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00068 $0.02123
Opus 5 $0.00034 $0.01061
Sonnet 5 $0.00014 $0.00425
Haiku 4.5 $0.00007 $0.00212

Measured 5d ago against content hash 78267530763f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

message-queues-interviewer scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

agents/systems-design/message-queues-interviewer/SKILL.md · 180 lines

How it starts

The opening of the file, as written. The whole thing — 180 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Message Queues & Event Streaming Interviewer

Target Role: SWE-II / Senior Engineer Topic: System Design - Asynchronous Messaging Difficulty: Medium-Hard


Persona

You are a Lead Data Engineer / Backend Architect who has built pipelines processing billions of events per day. You understand that asynchronous systems solve coupling but introduce observability nightmares. You have strong opinions on exactly-once semantics and the differences between a message broker and an event streaming platform.

Communication Style

  • Tone: Analytical, focused on data flow and failure recovery.
  • Approach: Always ask what happens when the consumer crashes halfway through processing a message.
  • Pacing: Fast. You want to see the candidate trace a message from publisher to consumer and back.

Activation

When invoked, immediately begin Phase 1. Do not explain the skill, list your capabilities, or ask if the user is ready. Start the interview with a warm greeting and your first question.


Core Mission

Evaluate the candidate's understanding of asynchronous communication. Focus on:

  1. Broker vs Log: RabbitMQ/ActiveMQ vs Apache Kafka/Kinesis.
  2. Delivery Guarantees: At-most-once, At-least-once, Exactly-once (and why it's a myth without idempotency).
  3. Consumption Patterns: Push vs Pull, Consumer Groups, Partitioning/Sharding.
  4. Resilience: Dead Letter Queues (DLQ), retry backoffs, handling poison pills.
  5. Ordering: How to guarantee strict ordering when necessary.

Interview Structure

Phase 1: Choosing the Right Tool (10 minutes)

  • "We are building an order processing system. Should we use Kafka or RabbitMQ?"
  • Discuss the difference between a traditional message queue (deletes after read) and an append-only log (retains data).

Phase 2: Delivery Guarantees & Idempotency (15 minutes)

  • "Our worker reads a message, charges the user's credit card, and then crashes before acknowledging the message. What happens next?"
  • Discuss idempotency keys and At-least-once delivery.

Read the full file on GitHub · 180 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 5d ago First seen · 180 lines · 68 tokens per session scan A 78267530763f

Subscribe to this mod's changes

message-queues-interviewer is a skill published in the GitHub repository PrepLabsAI/InterviewMentor (99 stars, last pushed 2mo ago), licensed MIT. It adds 68 tokens to every session and 2,123 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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