ninja

ninja is a skill for Claude Code from mohitmishra786/low-level-dev-skills. It costs 81 tokens per session (1,255 once invoked), scanned A, original, MIT.

A fast, low-level build executor that follows instructions in a build.ninja file to compile only what needs rebuilding.

In plain words
What is it for?
Use it to configure and run C or C++ builds, build selected targets, inspect full compiler commands, preview work without running it, and investigate rebuild decisions.
Why use it?
It helps diagnose build failures, control how many jobs run at once, and see why a target is being rebuilt. CMake can generate its instructions for Ninja.

Skill for Claude Code

Written for Claude Code: user-invocable in frontmatter.

not rated 198repo +5 2mo ago A scan Socket: passSnyk: passSkillSpector: pass 81 tokens original MIT

Good fit Use it to configure and run C or C++ builds, build selected targets, inspect full compiler commands, preview work without running it, and investigate rebuild decisions.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/mohitmishra786/low-level-dev-skills/ninja
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.

Any agent
npx skills add mohitmishra786/low-level-dev-skills --skill ninja
Clone the repo
git clone --depth 1 https://github.com/mohitmishra786/low-level-dev-skills

Made for: Claude Code.

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 ninja

README.md
[![agentmods](https://agentmods.dev/badge/skills/mohitmishra786/low-level-dev-skills/ninja/github.svg)](https://agentmods.dev/skills/mohitmishra786/low-level-dev-skills/ninja)
Your own site
<a href="https://agentmods.dev/skills/mohitmishra786/low-level-dev-skills/ninja"><img src="https://agentmods.dev/badge/skills/mohitmishra786/low-level-dev-skills/ninja/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for ninja

Your own site · 80×15
<a href="https://agentmods.dev/skills/mohitmishra786/low-level-dev-skills/ninja"><img src="https://agentmods.dev/badge/skills/mohitmishra786/low-level-dev-skills/ninja.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 81 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,255 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • Socket pass 20 Apr 2026
  • Snyk pass 20 Apr 2026
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 5.1 $0.00081 $0.01255
Opus 5 $0.00041 $0.00628
Sonnet 5 $0.00016 $0.00251
Haiku 4.5 $0.00008 $0.00126

Measured 10d ago against content hash 3a24fc325fb0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

ninja 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 10d 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.

skills/build-systems/ninja/SKILL.md · 181 lines

How it starts

The opening of the file, as written. The whole thing — 181 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Ninja

Purpose

Guide agents through Ninja as a build executor: diagnosing failures, controlling parallelism, generating from CMake, and understanding the .ninja file format when needed.

Triggers

  • "Ninja is failing — how do I get more output?"
  • "How do I use Ninja with CMake?"
  • "How many parallel jobs does Ninja use?"
  • "How do I add a custom build step in Ninja?"
  • "What is a build.ninja file?"

Workflow

1. Ninja as a CMake generator

The most common use of Ninja is as the build executor for CMake:

# Configure with Ninja
cmake -S . -B build -G Ninja
cmake --build build                    # uses ninja internally

# Or invoke ninja directly
cd build && ninja

# Specify parallelism
ninja -j4
ninja -j$(nproc)

# Build specific target
ninja myapp
ninja install

CMake also supports Ninja Multi-Config:

cmake -S . -B build -G "Ninja Multi-Config"
cmake --build build --config Release
cmake --build build --config Debug

2. Verbose output and diagnostics

# Show full commands (not just [CC] foo.c)
ninja -v

# Dry run (show what would be built)
ninja -n

# Show why a target needs rebuilding
ninja -d explain myapp

# Print all targets
ninja -t targets all

# Print targets grouped by rule
ninja -t targets rule cc

# Dependency graph (graphviz)
ninja -t graph myapp | dot -Tsvg -o deps.svg

3. Common Ninja flags

Flag Effect
-j N Parallel jobs (default: CPUs + 2)
-l N Don't start new jobs if load average > N
-k N Keep going after N failures (default 1)
-v Verbose: show full command lines
-n Dry run
-C dir Change to dir before doing anything
-t tool Run a sub-tool (clean, query, targets, graph, compdb)

4. Cleaning

ninja -t clean          # remove build outputs
ninja -t clean -g       # also remove generated files

Or via CMake:

cmake --build build --target clean

5. compile_commands.json

Read the full file on GitHub · 181 lines

Files

What ships with it

1 file 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. 10d ago First seen · 181 lines · 81 tokens per session scan A 3a24fc325fb0

Subscribe to this mod's changes

ninja is a skill published in the GitHub repository mohitmishra786/low-level-dev-skills (198 stars, last pushed 2mo ago), licensed MIT. It adds 81 tokens to every session and 1,255 once invoked, about $0.0004 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.

Related

Other skills, from other repositories

ecommerce-growth-strategy

E-commerce growth strategy advisor. Diagnoses current business health using unit economics (CAC, LTV, AOV, contribution margin), identifies the highest-impact growth opportunities across 5 levers (traffic, conversion, AOV, retention, expansion), and builds a prioritized 90-day growth roadmap. Uses the Ansoff Matrix…

nexscope-ai/eCommerce-Skills · 175 tokens

ecommerce-ppc-strategy-planner

Cross-platform PPC strategy planner for ecommerce businesses. Analyzes your product and margins, recommends the right advertising platforms (Google Ads, Meta Ads, TikTok Ads), calculates ROAS targets, allocates budget across channels, and generates platform-specific campaign briefs with ad copy and creative direction.…

nexscope-ai/eCommerce-Skills · 122 tokens

ecommerce-marketing-strategy-builder

Full-stack e-commerce marketing strategy builder. Analyzes your product, market, and competitors, then builds a complete omnichannel marketing plan covering paid ads, SEO, email/SMS, content marketing, social media, influencer partnerships, and referral programs. Includes target audience persona, competitive…

nexscope-ai/eCommerce-Skills · 112 tokens

competitor-price-analysis

Competitor pricing strategy analysis and market positioning. Price mapping, pricing gaps identification, elasticity signals evaluation, and strategic pricing optimization. Use when the user asks about competitor pricing, price analysis, pricing strategy, or competitive pricing research.

nexscope-ai/eCommerce-Skills · 50 tokens

warehouse-optimization

E-commerce warehouse and inventory optimization advisor. Analyzes inventory health, calculates safety stock and reorder points, performs ABC analysis, evaluates fulfillment costs, and provides actionable recommendations for improving efficiency. Supports all major fulfillment models: Self-fulfillment, Amazon FBA/FBM…

nexscope-ai/eCommerce-Skills · 132 tokens

supply-chain-optimization-tiktok

Supply Chain Bottleneck Analyzer for TikTok Shop sellers. Diagnose cash flow, inventory turnover, affiliate commissions, and return rates. Includes FBT cost analysis, influencer payout optimization, and viral product lifecycle management. No API key required for basic analysis.

nexscope-ai/eCommerce-Skills · 57 tokens