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Agent skill

L3 Core

by yennanliu in yennanliu/CS_basics

Report where the L3 core set stands and pick the next problems to drill from it.

No licenceAuto-check: notesDevelopment

Install L3 Core

skills CLI
$ npx skills add yennanliu/CS_basics --skill l3-core -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install yennanliu/CS_basics l3-core --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/yennanliu/CS_basics.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.claude/skills/l3-core .claude/skills/l3-core && rm -rf skills-src

Use ~/.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/

Facts

Skill name
l3-core
GitHub stars
141
Token cost
~2.2k tokens
SKILL.md length
1,146 words
Files
1
Skills in repo
16
Repo updated
First seen
Licence
None found

At a glance

Report where the L3 core set stands and pick the next problems to drill from it.

  • Works in 6 steps: Check the set is current → Read the state → Pick the session → …
  • Asked what to practise today
  • SKILL.md covers Why this exists, What the set is, Where the verdict comes from and Prime directives, plus 3 more sections
  • Calls python3

What it does

L3 Core is an agent skill from yennanliu/CS_basics. Report where the L3 core set stands and pick the next problems to drill from it. The set is Blind 75 plus the NeetCode 150 problems README marks MUST — 99 problems, held fixed in data/l3core.json so its ok share means something month to month — and the verdict for each is the latest annotation in data/progress.txt, not README's status column. Use when asked what to practise today, how ready the core set is, how many of Blind 75 are solid, which problems keep coming back, or to refresh the set after a MUST marker…

Its SKILL.md is about 2.2k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Development, covering Technical documentation. The repository describes itself as: My CS learning : algorithm, data structure, and system design | SE.

When your agent uses it

  • Asked what to practise today
  • How ready the core set is
  • How many of Blind 75 are solid
  • Which problems keep coming back

Example prompts

  • “/l3-core”
  • “/l3-core next 5”
  • “what should I drill today?”
  • “/l3-core”

Requirements

  • Python 3
  • Pre-approved tools (allowed-tools): Read, Glob, Grep, Bash

Workflow steps

6 steps, taken from the step headings in SKILL.md.

  1. Check the set is current
  2. Read the state
  3. Pick the session
  4. Drill, then hand off
  5. Track it monthly
  6. Report

What it can do on your machine

Read from SKILL.md and the folder at commit cb6b21b. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves these tools, so the agent can use them without asking each time:

    • Read
    • Glob
    • Grep
    • Bash

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • python3

    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

L3 Core loads about 2.2k tokens when it runs. Until then it costs about 178 tokens; SKILL.md has 1,146 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~178
When it runs · the whole SKILL.md, loaded when a task matches
~2.2k

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: notes

The automated check noted patterns worth knowing about, such as sudo or a known installer.

  • NotePre-approves every shell command (allowed-tools: Bash)SKILL.md
    allowed-tools: Read, Glob, Grep, Bash

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

Without a licence we can't republish the file, so here is its outline and opening line. It has 1,146 words (~2,195 tokens).

“Where each of the ~100 problems this repo measures itself on stands, and which five to do next.”

— opening of SKILL.md by yennanliu
name
l3-core
allowed-tools
Read, Glob, Grep, Bash

Read the full SKILL.md on GitHub

Files

Just SKILL.md in .claude/skills/l3-core of yennanliu/CS_basics.

Open the folder on GitHubat commit cb6b21b

Compare with similar skills

L3 Core 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.

L3 Core compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
L3 Core this skillyennanliu/CS_basics141—~2.2kAutomated safety check: NotesNone
Diagram Designcathrynlavery/diagram-design48k1 repos~7.6kAutomated safety check: PassMIT
Simple Englishmoeru-ai/airi50k2 repos~4.6kAutomated safety check: PassMIT
Doc SyncJetBrains/ideavim10k2 repos~2.6kAutomated safety check: PassMIT
Mailspring App ScreenshotsFoundry376/Mailspring18k—~1.5kAutomated safety check: PassGPL-3.0
Draw.io Diagram StudioAgents365-ai/drawio-skill10k—~2.4kAutomated safety check: NotesMIT

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Categories

Questions about L3 Core

What does L3 Core do?

Report where the L3 core set stands and pick the next problems to drill from it. L3 Core is an agent skill from yennanliu/CS_basics. Report where the L3 core set stands and pick the next problems to drill from it.

When should I use L3 Core?

L3 Core fits situations like: asked what to practise today; how ready the core set is; how many of Blind 75 are solid; which problems keep coming back.

How do I install L3 Core in Claude Code?

Run `npx skills add yennanliu/CS_basics --skill l3-core -a claude-code`. Or copy the skill folder (.claude/skills/l3-core in yennanliu/CS_basics) into .claude/skills/l3-core in your project. Claude Code loads it when a task matches its description.

How do I install L3 Core in Codex?

Run `npx skills add yennanliu/CS_basics --skill l3-core -a codex`. Or copy the skill folder (.claude/skills/l3-core in yennanliu/CS_basics) into .agents/skills/l3-core in your project. Codex loads it when a task matches its description.

Can I use L3 Core 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 yennanliu/CS_basics --skill l3-core -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/l3-core, .gemini/skills/l3-core, .github/skills/l3-core and .opencode/skills/l3-core in your project.

What does L3 Core need to run?

Going by SKILL.md and its folder, L3 Core needs the command-line tools its instructions call (python3). Our summary lists: Python 3. Its frontmatter pre-approves these tools: Read, Glob, Grep, Bash.

Does L3 Core 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 L3 Core safe to install?

Our automated static check of SKILL.md found notes only (pre-approves every shell command (allowed-tools: bash)), nothing it rates as a warning. It is not a guarantee. Review the folder before installing.

What licence does L3 Core use?

No licence was found for L3 Core or its repository. Without one, default copyright applies: ask the author before reusing or redistributing it.

How many tokens does L3 Core use?

About 2.2k tokens (SKILL.md is roughly 8.8k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to L3 Core?

Skills that share tags, products or a category with L3 Core: Diagram Design (cathrynlavery/diagram-design, 48k stars), Simple English (moeru-ai/airi, 50k stars), Doc Sync (JetBrains/ideavim, 10k stars) and Mailspring App Screenshots (Foundry376/Mailspring, 18k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains L3 Core?

yennanliu (a GitHub user) maintains it in yennanliu/CS_basics, which has 141 GitHub stars. The repository holds 16 skills in this directory. The repository was last updated on October 10, 2026.

Source: yennanliu/CS_basics on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.