Leetcode Py
wislertt/leetcode-py
Generates Python LeetCode practice environments and manages a 307-problem catalog with the lcpy CLI.
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.
Install System Design Case Catalog
$ npx skills add HoangNguyen0403/agent-skills-standard --skill system-design-case-catalog -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install HoangNguyen0403/agent-skills-standard system-design-case-catalog --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/HoangNguyen0403/agent-skills-standard.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/system-design/system-design-case-catalog .claude/skills/system-design-case-catalog && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "system-design-case-catalog" agent skill from https://github.com/HoangNguyen0403/agent-skills-standard/tree/develop/skills/system-design/system-design-case-catalog into .claude/skills/system-design-case-catalog/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "system-design-case-catalog", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/HoangNguyen0403/agent-skills-standard/tree/develop/skills/system-design/system-design-case-catalogType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add HoangNguyen0403/agent-skills-standard --skill system-design-case-catalog -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install HoangNguyen0403/agent-skills-standard system-design-case-catalog --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/HoangNguyen0403/agent-skills-standard.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/system-design/system-design-case-catalog .agents/skills/system-design-case-catalog && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "system-design-case-catalog" agent skill from https://github.com/HoangNguyen0403/agent-skills-standard/tree/develop/skills/system-design/system-design-case-catalog into .agents/skills/system-design-case-catalog/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "system-design-case-catalog", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add HoangNguyen0403/agent-skills-standard --skill system-design-case-catalog -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install HoangNguyen0403/agent-skills-standard system-design-case-catalog --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/HoangNguyen0403/agent-skills-standard.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/system-design/system-design-case-catalog .cursor/skills/system-design-case-catalog && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "system-design-case-catalog" agent skill from https://github.com/HoangNguyen0403/agent-skills-standard/tree/develop/skills/system-design/system-design-case-catalog into .cursor/skills/system-design-case-catalog/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "system-design-case-catalog", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/HoangNguyen0403/agent-skills-standard.git --path skills/system-design/system-design-case-catalog--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add HoangNguyen0403/agent-skills-standard --skill system-design-case-catalog -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install HoangNguyen0403/agent-skills-standard system-design-case-catalog --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/HoangNguyen0403/agent-skills-standard.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/system-design/system-design-case-catalog .gemini/skills/system-design-case-catalog && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "system-design-case-catalog" agent skill from https://github.com/HoangNguyen0403/agent-skills-standard/tree/develop/skills/system-design/system-design-case-catalog into .gemini/skills/system-design-case-catalog/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "system-design-case-catalog", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install HoangNguyen0403/agent-skills-standard system-design-case-catalogInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add HoangNguyen0403/agent-skills-standard --skill system-design-case-catalog -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/HoangNguyen0403/agent-skills-standard.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/system-design/system-design-case-catalog .github/skills/system-design-case-catalog && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "system-design-case-catalog" agent skill from https://github.com/HoangNguyen0403/agent-skills-standard/tree/develop/skills/system-design/system-design-case-catalog into .github/skills/system-design-case-catalog/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "system-design-case-catalog", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add HoangNguyen0403/agent-skills-standard --skill system-design-case-catalog -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install HoangNguyen0403/agent-skills-standard system-design-case-catalog --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/HoangNguyen0403/agent-skills-standard.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/system-design/system-design-case-catalog .opencode/skills/system-design-case-catalog && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "system-design-case-catalog" agent skill from https://github.com/HoangNguyen0403/agent-skills-standard/tree/develop/skills/system-design/system-design-case-catalog into .opencode/skills/system-design-case-catalog/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "system-design-case-catalog", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
system-design-case-catalog- GitHub stars
- 572
- Token cost
- ~1.1k tokens
- SKILL.md length
- 484 words
- Files
- 4 (incl. references)
- Skills in repo
- 211
- Repo updated
- First seen
- Licence
- MIT
At a glance
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.
- Interview practice
- SKILL.md covers Priority: P2 (MEDIUM), Defining Constraints, Coaching Mode and Production Case Routing, plus 3 more sections
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
- Naming the closest known shape for a new problem
What it does
System Design Case Catalog is an agent 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.
Its SKILL.md is about 1.1k tokens, which your agent loads only when the skill is triggered. The skill folder holds 5 other files, including reference files (for example `evals/evals.json`, `references/common-designs.md` and `references/production-case-packs.md`).
It sits in Data & Analytics, covering Interview preparation and Web scraping. The repository describes itself as: A collection of Agent Skills Standard and Best Practice for Programming Languages, Frameworks that help our AI Agent follow best practies on frameworks and programming laguages. The licence is MIT.
When your agent uses it
- Interview practice
- Naming the closest known shape for a new problem
Example prompts
- “/system-design-case-catalog”
What it can do on your machine
Read from SKILL.md and the folder at commit b529c2d. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md.
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
System Design Case Catalog loads about 1.1k tokens when it runs, and up to ~8.3k if it reads all its reference files. Until then it costs about 76 tokens; SKILL.md has 484 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
The full file from HoangNguyen0403/agent-skills-standard at commit b529c2d, republished under its MIT licence (© HoangNguyen0403). 484 words, ~1,098 tokens.
Download SKILL.mdSave it as
.claude/skills/system-design-case-catalog/SKILL.md (or your agent's skills folder). This skill also uses 3 other files; get the full folder from GitHub.- name
- system-design-case-catalog
- description
- 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.
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 |
| Web crawler | Politeness and dedupe at scale, not raw fetching | Frontier queue per host, robots cache, URL fingerprint dedupe, freshness policy |
| Unique id | Ordered, unique, generated without a central lock | Snowflake-style timestamp plus node plus sequence; clock-skew handling |
| Video streaming | Bitrate ladder and CDN economics, not the upload | Transcode pipeline per rendition, adaptive manifests (HLS/DASH), edge cache hit ratio as the cost lever |
| Ride hailing | Geo matching under moving supply and demand | Geohash or S2 cells, driver location stream with TTL, matching window and surge as a pricing signal |
| Payment ledger | Exactly-once effect under retries and partial failure | Idempotency key per attempt, double-entry ledger, reconciliation job against the processor |
Show full SKILL.md (224 more words)Show less
Coaching Mode
- Mock rounds, the clock, the rubric, and the debrief live in
system-design-interview-coaching; this catalog is its problem bank. - Give the model answer only after the candidate commits to an approach; the defining constraint above is the follow-up question when they stall.
- For production practice, lazy-load production case packs. They are synthetic fixtures unless a named primary source says otherwise; never present their numbers or timelines as deployed facts.
Production Case Routing
- Choose one pack only after stating the profile, workload, SLO, team, budget, and invariant. Recalculate all numbers for the user's system.
- Carry the pack's selected views through the HLD-to-LLD trace; use only the view that answers the current question and do not create a second diagramming lane.
Reuse Rules
- Map a new problem to the nearest catalog shape, then re-derive the numbers. The shape transfers, the sizing never does.
- State where the analogy breaks before borrowing the design.
- A catalog answer is a starting hypothesis, not a substitute for intake and estimation.
Anti-Patterns
- No pattern-matching without numbers: a known shape still needs this system's QPS and data volume.
- No interview answer as a build plan: production adds migration, cost, compliance, and team constraints.
- No full solution dump in coaching mode: the value is in the questions asked, not the answer given.
References
- Common Designs - per-problem sketch with constraints, components, and trade-offs
© HoangNguyen0403, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file
Files
SKILL.md and 3 other files (references) in skills/system-design/system-design-case-catalog of HoangNguyen0403/agent-skills-standard.
- SKILL.md
- evals/evals.json
- references/common-designs.md
- references/production-case-packs.md
Open the folder on GitHubat commit b529c2d
Compare with similar skills
System Design Case Catalog next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| System Design Case Catalog this skillHoangNguyen0403/agent-skills-standard | 572 | — | ~1.1k | Automated safety check: Pass | MIT | |
| Leetcode Pywislertt/leetcode-py | 142 | — | ~1.4k | Automated safety check: Pass | Apache-2.0 | |
| Monitor With HaolemeHaolemeApp/Haoleme | 157 | — | ~1.3k | Automated safety check: Pass | AGPL-3.0 | |
| Add ScraperRealEstateWebTools/property_web_scraper | 132 | — | ~1.4k | Automated safety check: Pass | MIT | |
| Name Framework Migration First Stepopensanctions/opensanctions | 834 | — | ~1.1k | Automated safety check: Pass | MIT | |
| Youtube API Skillbrowser-act/skills | 6.1k | 1 repos | ~1.6k | Automated safety check: Pass | MIT |
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Related
Questions about System Design Case Catalog
What does System Design Case Catalog do?
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. System Design Case Catalog is an agent 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.
When should I use System Design Case Catalog?
System Design Case Catalog fits situations like: interview practice; naming the closest known shape for a new problem.
How do I install System Design Case Catalog in Claude Code?
Run `npx skills add HoangNguyen0403/agent-skills-standard --skill system-design-case-catalog -a claude-code`. Or copy the skill folder (skills/system-design/system-design-case-catalog in HoangNguyen0403/agent-skills-standard) into .claude/skills/system-design-case-catalog in your project. Claude Code loads it when a task matches its description.
How do I install System Design Case Catalog in Codex?
Run `npx skills add HoangNguyen0403/agent-skills-standard --skill system-design-case-catalog -a codex`. Or copy the skill folder (skills/system-design/system-design-case-catalog in HoangNguyen0403/agent-skills-standard) into .agents/skills/system-design-case-catalog in your project. Codex loads it when a task matches its description.
Can I use System Design Case Catalog in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add HoangNguyen0403/agent-skills-standard --skill system-design-case-catalog -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/system-design-case-catalog, .gemini/skills/system-design-case-catalog, .github/skills/system-design-case-catalog and .opencode/skills/system-design-case-catalog in your project.
What does System Design Case Catalog need to run?
SKILL.md names no scripts, command-line tools or credentials: System Design Case Catalog is instructions for the agent only.
Does System Design Case Catalog access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is System Design Case Catalog safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does System Design Case Catalog use?
System Design Case Catalog is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.
How many tokens does System Design Case Catalog use?
About 1.1k tokens (SKILL.md is roughly 4.4k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 7.2k tokens, read only when the agent opens those files.
What are the alternatives to System Design Case Catalog?
Skills that share tags, products or a category with System Design Case Catalog: Leetcode Py (wislertt/leetcode-py, 142 stars), Monitor With Haoleme (HaolemeApp/Haoleme, 157 stars), Add Scraper (RealEstateWebTools/property_web_scraper, 132 stars) and Name Framework Migration First Step (opensanctions/opensanctions, 834 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains System Design Case Catalog?
HoangNguyen0403 (a GitHub user) maintains it in HoangNguyen0403/agent-skills-standard, which has 572 GitHub stars. The repository holds 211 skills in this directory. The repository was last updated on October 9, 2026.
Source: HoangNguyen0403/agent-skills-standard on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.