Web Application Testing
anthropics/skills
Tests local web applications with Python Playwright scripts, checking frontend behavior, capturing screenshots and reading browser console logs.
This skill provides guidance for implementing custom compression encoders that must be compatible with existing decoders (especially arithmetic coding).
Install Write Compressor
$ npx skills add lazyFrogLOL/Harness_Engineering --skill write-compressor -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install lazyFrogLOL/Harness_Engineering write-compressor --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/lazyFrogLOL/Harness_Engineering.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/write-compressor .claude/skills/write-compressor && 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 "write-compressor" agent skill from https://github.com/lazyFrogLOL/Harness_Engineering/tree/master/skills/write-compressor into .claude/skills/write-compressor/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "write-compressor", 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/lazyFrogLOL/Harness_Engineering/tree/master/skills/write-compressorType 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 lazyFrogLOL/Harness_Engineering --skill write-compressor -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install lazyFrogLOL/Harness_Engineering write-compressor --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/lazyFrogLOL/Harness_Engineering.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/write-compressor .agents/skills/write-compressor && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "write-compressor" agent skill from https://github.com/lazyFrogLOL/Harness_Engineering/tree/master/skills/write-compressor into .agents/skills/write-compressor/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "write-compressor", 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 lazyFrogLOL/Harness_Engineering --skill write-compressor -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install lazyFrogLOL/Harness_Engineering write-compressor --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/lazyFrogLOL/Harness_Engineering.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/write-compressor .cursor/skills/write-compressor && 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 "write-compressor" agent skill from https://github.com/lazyFrogLOL/Harness_Engineering/tree/master/skills/write-compressor into .cursor/skills/write-compressor/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "write-compressor", 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/lazyFrogLOL/Harness_Engineering.git --path skills/write-compressor--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 lazyFrogLOL/Harness_Engineering --skill write-compressor -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install lazyFrogLOL/Harness_Engineering write-compressor --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/lazyFrogLOL/Harness_Engineering.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/write-compressor .gemini/skills/write-compressor && 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 "write-compressor" agent skill from https://github.com/lazyFrogLOL/Harness_Engineering/tree/master/skills/write-compressor into .gemini/skills/write-compressor/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "write-compressor", 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 lazyFrogLOL/Harness_Engineering write-compressorInstalls 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 lazyFrogLOL/Harness_Engineering --skill write-compressor -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/lazyFrogLOL/Harness_Engineering.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/write-compressor .github/skills/write-compressor && 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 "write-compressor" agent skill from https://github.com/lazyFrogLOL/Harness_Engineering/tree/master/skills/write-compressor into .github/skills/write-compressor/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "write-compressor", 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 lazyFrogLOL/Harness_Engineering --skill write-compressor -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install lazyFrogLOL/Harness_Engineering write-compressor --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/lazyFrogLOL/Harness_Engineering.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/write-compressor .opencode/skills/write-compressor && 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 "write-compressor" agent skill from https://github.com/lazyFrogLOL/Harness_Engineering/tree/master/skills/write-compressor into .opencode/skills/write-compressor/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "write-compressor", 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
write-compressor- GitHub stars
- 128
- Token cost
- ~1.8k tokens
- SKILL.md length
- 770 words
- Files
- 1
- Skills in repo
- 32
- Repo updated
- First seen
- Licence
- None found
At a glance
This skill provides guidance for implementing custom compression encoders that must be compatible with existing decoders (especially arithmetic coding).
- Works in 12 steps: Decoder-First Analysis → Incremental Complexity Approach → Dual Simulation Verification → …
- Testing & QA work in your project
- SKILL.md covers Overview, Critical Success Factors, Verification Strategy and Common Pitfalls, plus 3 more sections
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
What it does
Write Compressor is an agent skill from lazyFrogLOL/Harness_Engineering. This skill provides guidance for implementing custom compression encoders that must be compatible with existing decoders (especially arithmetic coding). It should be used when the task requires writing a compressor/encoder that produces output compatible with a given decompressor/decoder, or when implementing arithmetic coding or similar bit-level compression schemes.
Its SKILL.md is about 1.8k 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 Testing & QA.
When your agent uses it
- Testing & QA work in your project
Example prompts
- “/write-compressor”
Requirements
- Python 3
Workflow steps
12 steps, taken from the step headings in SKILL.md.
- Decoder-First Analysis
- Incremental Complexity Approach
- Dual Simulation Verification
- State Synchronization
- Trial-and-Error Implementation
- Wrong Byte Output Formula
- Premature Optimization
- Testing Full Files Before Simple Cases
- Insufficient Decoder Analysis
- Analysis (Do Not Skip)
- Minimal Implementation
- Incremental Extension
What it can do on your machine
Read from SKILL.md and the folder at commit cae3b25. 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 (its code samples are python and c).
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
Write Compressor loads about 1.8k tokens when it runs. Until then it costs about 97 tokens; SKILL.md has 770 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
Without a licence we can't republish the file, so here is its outline and opening line. It has 770 words (~1,773 tokens).
“This skill guides the implementation of compression encoders that must produce output compatible with an existing decoder. The key challenge is ensuring encoder state transitions exactly mirror decoder expectations—particularly critical for arithmetic coding where even minor state drift causes decompression…”
- name
- write-compressor
Files
Just SKILL.md in skills/write-compressor of lazyFrogLOL/Harness_Engineering.
Open the folder on GitHubat commit cae3b25
Compare with similar skills
Write Compressor 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 |
|---|---|---|---|---|---|---|
| Write Compressor this skilllazyFrogLOL/Harness_Engineering | 128 | — | ~1.8k | Automated safety check: Pass | None | |
| Web Application Testinganthropics/skills | 180k | 51 repos | ~966 | Automated safety check: Pass | Apache-2.0 | |
| Diagnosing Bugsfossasia/eventyay-interpretation | 1.6k | 31 repos | ~2.1k | Automated safety check: Pass | Apache-2.0 | |
| TDDfossasia/eventyay-interpretation | 1.6k | 28 repos | ~1.1k | Automated safety check: Pass | Apache-2.0 | |
| TDD WorkflowhellangleZ/burn-in-cceverywhere-ralph | 112 | 11 repos | ~2.4k | Automated safety check: Pass | None | |
| TDDsanity-io/sanity | 6.4k | 20 repos | ~1k | Automated safety check: Pass | MIT |
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- Official
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fossasia/eventyay-interpretation
Diagnosis loop for hard bugs and performance regressions. An agent skill from fossasia/eventyay-interpretation.
TDD
fossasia/eventyay-interpretation
Test-driven development. An agent skill from fossasia/eventyay-interpretation.
TDD Workflow
hellangleZ/burn-in-cceverywhere-ralph
A skill your agent uses when writing new features, fixing bugs, or refactoring code.
- Official
TDD
sanity-io/sanity
Test-driven development with red-green-refactor loop. An agent skill from sanity-io/sanity.
Context Driven Development
Ibrahim-3d/orchestrator-supaconductor
A skill your agent uses when working with Conductor's context-driven development methodology, managing project context artifacts, or understanding the relationship between product.md, tech-stack.md…
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Categories
Questions about Write Compressor
What does Write Compressor do?
This skill provides guidance for implementing custom compression encoders that must be compatible with existing decoders (especially arithmetic coding). Write Compressor is an agent skill from lazyFrogLOL/Harness_Engineering. This skill provides guidance for implementing custom compression encoders that must be compatible with existing decoders (especially arithmetic coding).
When should I use Write Compressor?
Write Compressor fits situations like: testing & QA work in your project.
How do I install Write Compressor in Claude Code?
Run `npx skills add lazyFrogLOL/Harness_Engineering --skill write-compressor -a claude-code`. Or copy the skill folder (skills/write-compressor in lazyFrogLOL/Harness_Engineering) into .claude/skills/write-compressor in your project. Claude Code loads it when a task matches its description.
How do I install Write Compressor in Codex?
Run `npx skills add lazyFrogLOL/Harness_Engineering --skill write-compressor -a codex`. Or copy the skill folder (skills/write-compressor in lazyFrogLOL/Harness_Engineering) into .agents/skills/write-compressor in your project. Codex loads it when a task matches its description.
Can I use Write Compressor 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 lazyFrogLOL/Harness_Engineering --skill write-compressor -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/write-compressor, .gemini/skills/write-compressor, .github/skills/write-compressor and .opencode/skills/write-compressor in your project.
What does Write Compressor need to run?
SKILL.md names no scripts, command-line tools or credentials: Write Compressor is instructions for the agent only. Our summary lists: Python 3.
Does Write Compressor 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 Write Compressor 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 Write Compressor use?
No licence was found for Write Compressor or its repository. Without one, default copyright applies: ask the author before reusing or redistributing it.
How many tokens does Write Compressor use?
About 1.8k tokens (SKILL.md is roughly 7.1k 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 Write Compressor?
Skills that share tags, products or a category with Write Compressor: Web Application Testing (anthropics/skills, 180k stars), Diagnosing Bugs (fossasia/eventyay-interpretation, 1.6k stars), TDD (fossasia/eventyay-interpretation, 1.6k stars) and TDD Workflow (hellangleZ/burn-in-cceverywhere-ralph, 112 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Write Compressor?
lazyFrogLOL (a GitHub user) maintains it in lazyFrogLOL/Harness_Engineering, which has 128 GitHub stars. The repository holds 32 skills in this directory. The repository was last updated on May 18, 2026.
Source: lazyFrogLOL/Harness_Engineering on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.