cross-origin-isolation SKILL.md skillA
cross-origin-isolation from thedaviddias/front-end-checklist is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add thedaviddias/front-end-checklist/cross-origin-isolation@git:20261004.4b0ddb9Pins git:20261004.4b0ddb9 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- thedaviddias/front-end-checklist
- Path
skills/cross-origin-isolation/SKILL.md- Versions recorded
- 2
- Latest version
- git:20261004.4b0ddb9, committed Oct 4, 2026
- First version recorded
- May 29, 2026
- Size
- 2,257 bytes
- Repository stars
- 74,516
- License
- MIT
Use when reviewing security-sensitive web apps, SharedArrayBuffer usage, worker-heavy apps, editors, or measurement features that require cross-origin isolation. Check both headers and real browser behavior.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Use COOP, COEP, and CORP for cross-origin isolation when needed Cross-origin isolation reduces opener-based attacks and XS-Leak risk, and it is required for powerful browser features such as SharedArrayBuffer in modern browsers. It also breaks integrations if deployed carelessly, so it needs a deliberate rollout rather than a copy-pasted header block. ## Quick Reference - Use `Cross-Origin-Opener-Policy` and `Cross-Origin-Embedder-Policy` together when you need cross-origin isolation - Audit every cross-origin script, iframe, image, worker, and font before enforcing COEP - Serve embeddable resources with CORS or `Cross-Origin-Resource-Policy` as appropriate - Verify `self.crossOriginIsolated === true` before depending on isolated-only features ## Check Review security headers and embedded resources for cross-origin isolation. Check whether the app needs COOP/COEP, whether resources are compatible with COEP, and whether the runtime actually becomes crossOriginIsolated. ## Fix Add COOP and COEP only after auditing dependencies, ensure subresources use CORP or CORS as required, and verify the final document becomes crossOriginIsolated in the browser. ## Explain …
Read the whole file at its exact version.
How to install
mdr add thedaviddias/front-end-checklist/cross-origin-isolation@sha256:82005beaad1b4d2aThe line at the top of this page pins the label git:20261004.4b0ddb9, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_lemptkrqfzbfjxyh)
4 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 2 versions of this file, between May 29, 2026 and Oct 4, 2026, about one every 128 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20261004.4b0ddb9 latest | 2026-10-04 | 4b0ddb9 | 2,257 B | A | view · diff |
| git:20260529.7c05904 | 2026-05-29 | 7c05904 | 2,263 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (2257 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
thedaviddias/front-end-checklist · 74,516 stars · license MIT · pushed 2026-10-06 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_lemptkrqfzbfjxyh GET https://markdownregistry.com/api/v1/resolve?ref=thedaviddias/front-end-checklist/cross-origin-isolation GET https://markdownregistry.com/api/v1/blob/82005beaad1b4d2aec03c4ea0ea39486b54fd293eaacddf150cff5ce58471b27
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.