Home / hoangnguyen0403 / agent-skills-standard · .claude/skills/system-design/system-design-case-catalog/SKILL.md · GitHub

system-design-case-catalog skillA

This file is byte-identical to the first copy the registry indexed. Same content hash, same audit grade.

system-design-case-catalog is agent-read markdown (skill) from hoangnguyen0403/agent-skills-standard: Answer classic system design problems as constraint-to-solution sketches and coach interview practice: URL shortener, rate limiter, news feed, chat, notification, autocomplete, crawler, unique id. Use for interview practice or naming the closest known shape for a new problem..

Indexed from public GitHub and served as immutable, content-addressed versions. Install it pinned to an exact SHA-256 with the mdr CLI, and every file is verified against the hash recorded here before it reaches your agent. The deterministic audit below grades the latest version, and the same file always earns the same grade.

What the file says

# Case Catalog

## **Priority: P2 (MEDIUM)**

Each classic problem has one defining constraint. Name it first; the rest of the design follows.

## Defining Constraints

| Problem | Defining constraint | Decisions that follow |
| --- | --- | --- |
| URL shortener | Read-heavy by ~100:1, key must be short and unique | Base62 of a distributed counter, cache-first read path, 301 vs 302 choice |
| Rate limiter | Decision must be cheap, shared, and correct under concurrency | Token bucket in a shared counter, fail-open or fail-closed rule, `429` plus `Retry-After` |
| News feed | Fan-out cost versus read latency, with celebrity skew | Push for normal accounts, pull for celebrities, hybrid merge at read |
| Chat | Delivery guarantees and presence at persistent-connection scale | WebSocket gateways, per-conversation ordering, offline queue, read receipts |
| Notification | Multi-channel delivery with retries and dedupe | Queue per channel, idempotency key, user preference and quiet hours |
| Autocomplete | Sub-100ms prefix lookup over a huge term space | Trie or prefix index in memory, precomputed top-k per prefix, async rebuild |
…

Read the whole file at its exact version.

How to install

Latest version
mdr add hoangnguyen0403/agent-skills-standard/system-design-case-catalog@git:20260913.a7ccfad
Exact content
mdr add hoangnguyen0403/agent-skills-standard/system-design-case-catalog@sha256:8093d8b91a00bc1f

Pin to a label to follow the author's releases, or to a sha256 to freeze the exact bytes forever. Either way the resolved hash is written to mdr.lock, and mdr install reproduces it on any machine.

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Versions

versioncommittedcommitsizeaudit
git:20260913.a7ccfad latest2026-09-13 a7ccfad 3,610 BA view · diff
git:20260830.00e03f42026-08-30 00e03f4 3,289 BA view

Audit of the latest version

A  17 of 17 checks passed. Deterministic, no model, same answer every run.
  • pass: Frontmatter block present
  • pass: Frontmatter declares a name
  • pass: Frontmatter declares a description
  • pass: Size between 200 bytes and 200 KB (3610 bytes)
  • pass: No zero-width or bidi control characters
  • pass: No instruction hidden inside an HTML comment
  • pass: No link to an exfiltration or paste host
  • pass: No credential-shaped string
  • pass: No instruction to send local credentials anywhere
  • pass: No text hidden with inline styles
  • pass: No prompt-injection phrasing
  • pass: No curl or wget piped into a shell
  • pass: No recursive delete of root, home or parent
  • pass: No instruction to read or print local credentials
  • pass: No base64 blob over 200 characters
  • pass: No link to a raw IP address
  • pass: No script tag

Source

GitHub

hoangnguyen0403/agent-skills-standard · 571 stars · license MIT · pushed 2026-09-24 · branch develop

API

GET https://markdownregistry.com/api/v1/artifacts/art_i4wuljtvhxgajapd
GET https://markdownregistry.com/api/v1/resolve?ref=hoangnguyen0403/agent-skills-standard/system-design-case-catalog
GET https://markdownregistry.com/api/v1/blob/8093d8b91a00bc1f440bbea943260ff43e4d111b0ff650c8364c61fc273cbcb2

Your agent does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.

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system-design-case-catalog skill
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