Triage Support Bundle
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Investigate a Netdata support bundle offline - the archive netdata-support-bundle produces - to explain one host's alerts, missing data, collector failures, crashes, high CPU or memory, streaming…
A skill your agent uses when reviewing scripts, client components, bundles, or runtime behavior related to Handle cross-origin requests securely.
MITAuto-check passed
Install Cross Origin Security
$ npx skills add thedaviddias/Front-End-Checklist --skill cross-origin-security -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install thedaviddias/Front-End-Checklist cross-origin-security --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/thedaviddias/Front-End-Checklist.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/cross-origin-security .claude/skills/cross-origin-security && 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 "cross-origin-security" agent skill from https://github.com/thedaviddias/Front-End-Checklist/tree/main/skills/cross-origin-security into .claude/skills/cross-origin-security/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "cross-origin-security", 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/thedaviddias/Front-End-Checklist/tree/main/skills/cross-origin-securityType 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 thedaviddias/Front-End-Checklist --skill cross-origin-security -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install thedaviddias/Front-End-Checklist cross-origin-security --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/thedaviddias/Front-End-Checklist.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/cross-origin-security .agents/skills/cross-origin-security && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "cross-origin-security" agent skill from https://github.com/thedaviddias/Front-End-Checklist/tree/main/skills/cross-origin-security into .agents/skills/cross-origin-security/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "cross-origin-security", 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 thedaviddias/Front-End-Checklist --skill cross-origin-security -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install thedaviddias/Front-End-Checklist cross-origin-security --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/thedaviddias/Front-End-Checklist.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/cross-origin-security .cursor/skills/cross-origin-security && 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 "cross-origin-security" agent skill from https://github.com/thedaviddias/Front-End-Checklist/tree/main/skills/cross-origin-security into .cursor/skills/cross-origin-security/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "cross-origin-security", 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/thedaviddias/Front-End-Checklist.git --path skills/cross-origin-security--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 thedaviddias/Front-End-Checklist --skill cross-origin-security -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install thedaviddias/Front-End-Checklist cross-origin-security --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/thedaviddias/Front-End-Checklist.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/cross-origin-security .gemini/skills/cross-origin-security && 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 "cross-origin-security" agent skill from https://github.com/thedaviddias/Front-End-Checklist/tree/main/skills/cross-origin-security into .gemini/skills/cross-origin-security/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "cross-origin-security", 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 thedaviddias/Front-End-Checklist cross-origin-securityInstalls 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 thedaviddias/Front-End-Checklist --skill cross-origin-security -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/thedaviddias/Front-End-Checklist.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/cross-origin-security .github/skills/cross-origin-security && 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 "cross-origin-security" agent skill from https://github.com/thedaviddias/Front-End-Checklist/tree/main/skills/cross-origin-security into .github/skills/cross-origin-security/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "cross-origin-security", 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 thedaviddias/Front-End-Checklist --skill cross-origin-security -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install thedaviddias/Front-End-Checklist cross-origin-security --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/thedaviddias/Front-End-Checklist.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/cross-origin-security .opencode/skills/cross-origin-security && 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 "cross-origin-security" agent skill from https://github.com/thedaviddias/Front-End-Checklist/tree/main/skills/cross-origin-security into .opencode/skills/cross-origin-security/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "cross-origin-security", 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
cross-origin-security- GitHub stars
- 74k
- Token cost
- ~595 tokens
- SKILL.md length
- 237 words
- Files
- 2 (incl. references)
- Skills in repo
- 390
- Repo updated
- First seen
- Licence
- MIT
At a glance
A skill your agent uses when reviewing scripts, client components, bundles, or runtime behavior related to Handle cross-origin requests securely.
- Reviewing scripts
- SKILL.md covers Quick Reference, Check, Fix and Explain, plus 1 more section
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
- Client components
What it does
Cross Origin Security is an agent skill from thedaviddias/Front-End-Checklist. Use when reviewing scripts, client components, bundles, or runtime behavior related to Handle cross-origin requests securely. Inspect both source code and the browser execution path so fixes target the real bottleneck or bug.
Its SKILL.md is about 600 tokens, which your agent loads only when the skill is triggered. The skill folder holds 2 other files, including reference files (for example `references/rule.md`).
The repository describes itself as: 🗂 The essential checklist for modern web development, for humans and AI agents. The licence is MIT.
When your agent uses it
- Reviewing scripts
- Client components
- Runtime behavior related to Handle cross-origin requests securely
Example prompts
- “/cross-origin-security”
What it can do on your machine
Read from SKILL.md and the folder at commit e8d14d0. 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
Links to these hosts (documentation or services it may open):
frontendchecklist.io
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
Cross Origin Security loads about 595 tokens when it runs, and up to ~1.9k if it reads all its reference files. Until then it costs about 62 tokens; SKILL.md has 237 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 thedaviddias/Front-End-Checklist at commit e8d14d0, republished under its MIT licence (© thedaviddias). 237 words, ~595 tokens.
Download SKILL.mdSave it as
.claude/skills/cross-origin-security/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.- name
- cross-origin-security
- description
- Use when reviewing scripts, client components, bundles, or runtime behavior related to Handle cross-origin requests securely. Inspect both source code and the browser execution path so fixes target the real bottleneck or bug.
- metadata.category
- javascript
- metadata.priority
- high
- metadata.difficulty
- intermediate
- metadata.estimatedTime
- 20
- metadata.source
- frontendchecklist.io
- metadata.url
- https://frontendchecklist.io/rules/javascript/cross-origin-security
Handle cross-origin requests securely
The Same-Origin Policy is the browser's primary defense against malicious sites stealing data or performing actions on behalf of your users. Misconfiguring CORS or failing to validate postMessage origins can allow attackers to bypass this protection — reading private data, submitting forms as users, or injecting content into your pages.
Quick Reference
- Always verify event.origin before processing postMessage data
- Never set Access-Control-Allow-Origin: * for authenticated endpoints
- Validate and sanitize all data received from cross-origin messages
- Use SameSite cookies to prevent CSRF from cross-origin requests
- Reject unvalidated redirect targets such as
next,redirect, orcallbackUrl
Check
Check this code for insecure cross-origin patterns: missing origin validation in postMessage listeners, overly permissive CORS settings, and missing CSRF protections. Flag redirect parameters that accept arbitrary external URLs.
Fix
Add origin validation to postMessage listeners and review CORS configuration to ensure it's not overly permissive for authenticated routes. Reject or allow-list untrusted redirect destinations before navigating.
Explain
Explain the Same-Origin Policy, how CORS works, and how to securely use postMessage for cross-origin communication.
Code Review
Review scripts, client components, and browser execution paths related to Handle cross-origin requests securely. Flag exact imports, event handlers, runtime side effects, or blocking operations that violate the rule, and state how the change should be verified in the browser. Check login, logout, SSO, and return-to flows for open redirects.
For full implementation details, code examples, and framework-specific guidance,
see references/rule.md.
Rule page: https://frontendchecklist.io/rules/javascript/cross-origin-security
© thedaviddias, 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 1 other file (references) in skills/cross-origin-security of thedaviddias/Front-End-Checklist.
- SKILL.md
- references/rule.md
Open the folder on GitHubat commit e8d14d0
Compare with similar skills
Cross Origin Security 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 |
|---|---|---|---|---|---|---|
| Cross Origin Security this skillthedaviddias/Front-End-Checklist | 74k | — | ~595 | Automated safety check: Pass | MIT | |
| Triage Support Bundlenetdata/netdata | 81k | — | ~2.7k | Automated safety check: Pass | GPL-3.0 | |
| Origin APIcursor/plugins | 10k | — | ~694 | Automated safety check: Pass | MIT | |
| Analyzing Backend BundleTriliumNext/Trilium | 38k | — | ~2.6k | Automated safety check: Pass | AGPL-3.0 | |
| Next Bundle Optimizervercel/next.js | 143k | — | ~2.4k | Automated safety check: Pass | MIT | |
| Optimize Bundle Sizeelastic/kibana | 21k | — | ~794 | Automated safety check: Pass | Custom licence |
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- Official
Origin API
cursor/plugins
Routes questions about the Cursor Origin API to the right section of the Origin docs and names the few rules to check first.
Analyzing Backend Bundle
TriliumNext/Trilium
A skill your agent uses when analyzing the server/desktop backend bundle — "what does the server load at startup?", "is <dependency lazy on the backend?", "why is <package in the startup set?", "how…
- Official
Next Bundle Optimizer
vercel/next.js
Audit and reduce Next.js browser initial-load work. An agent skill from vercel/next.js.
- Official
Optimize Bundle Size
elastic/kibana
Reduce plugin page load bundle size and avoid unnecessary increases in packages/kbn-rspack-optimizer/limits.yml.
Production Bundle Audit
keybase/client
Builds the desktop Vite and iOS or Android Metro production bundles and checks them for tree-shaking problems, such as mobile-only modules leaking into the desktop build.
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Questions about Cross Origin Security
What does Cross Origin Security do?
A skill your agent uses when reviewing scripts, client components, bundles, or runtime behavior related to Handle cross-origin requests securely. Cross Origin Security is an agent skill from thedaviddias/Front-End-Checklist. Use when reviewing scripts, client components, bundles, or runtime behavior related to Handle cross-origin requests securely.
When should I use Cross Origin Security?
Cross Origin Security fits situations like: reviewing scripts; client components; runtime behavior related to Handle cross-origin requests securely.
How do I install Cross Origin Security in Claude Code?
Run `npx skills add thedaviddias/Front-End-Checklist --skill cross-origin-security -a claude-code`. Or copy the skill folder (skills/cross-origin-security in thedaviddias/Front-End-Checklist) into .claude/skills/cross-origin-security in your project. Claude Code loads it when a task matches its description.
How do I install Cross Origin Security in Codex?
Run `npx skills add thedaviddias/Front-End-Checklist --skill cross-origin-security -a codex`. Or copy the skill folder (skills/cross-origin-security in thedaviddias/Front-End-Checklist) into .agents/skills/cross-origin-security in your project. Codex loads it when a task matches its description.
Can I use Cross Origin Security 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 thedaviddias/Front-End-Checklist --skill cross-origin-security -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/cross-origin-security, .gemini/skills/cross-origin-security, .github/skills/cross-origin-security and .opencode/skills/cross-origin-security in your project.
What does Cross Origin Security need to run?
SKILL.md names no scripts, command-line tools or credentials: Cross Origin Security is instructions for the agent only.
Does Cross Origin Security access the network?
SKILL.md names 1 domain. As links in the text: frontendchecklist.io. This is read from the text; nothing was executed.
Is Cross Origin Security 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 Cross Origin Security use?
Cross Origin Security 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 Cross Origin Security use?
About 595 tokens (SKILL.md is roughly 2.4k 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 1.3k tokens, read only when the agent opens those files.
What are the alternatives to Cross Origin Security?
Skills that share tags, products or a category with Cross Origin Security: Triage Support Bundle (netdata/netdata, 81k stars), Origin API (cursor/plugins, 10k stars), Analyzing Backend Bundle (TriliumNext/Trilium, 38k stars) and Next Bundle Optimizer (vercel/next.js, 143k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Cross Origin Security?
thedaviddias (a GitHub user) maintains it in thedaviddias/Front-End-Checklist, which has 74,412 GitHub stars. The repository holds 390 skills in this directory. The repository was last updated on October 6, 2026.
Source: thedaviddias/Front-End-Checklist on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.