Fla Ascend Performance
fla-org/flash-linear-attention
Guidelines for Ascend NPU kernel / Triton-Ascend backend performance work in the FLA repo.
Test browser capability transfer across postMessage, opener, frame, portal, worker, service-worker, BroadcastChannel, MessagePort, and extension messaging boundaries.
Install Test Browser Messaging Boundaries
$ npx skills add cyberful/cyberful --skill test-browser-messaging-boundaries -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install cyberful/cyberful test-browser-messaging-boundaries --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/cyberful/cyberful.git skills-src && mkdir -p .claude/skills && cp -r skills-src/cyberful/builtin/skills/test-browser-messaging-boundaries .claude/skills/test-browser-messaging-boundaries && 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 "test-browser-messaging-boundaries" agent skill from https://github.com/cyberful/cyberful/tree/main/cyberful/builtin/skills/test-browser-messaging-boundaries into .claude/skills/test-browser-messaging-boundaries/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "test-browser-messaging-boundaries", 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/cyberful/cyberful/tree/main/cyberful/builtin/skills/test-browser-messaging-boundariesType 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 cyberful/cyberful --skill test-browser-messaging-boundaries -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install cyberful/cyberful test-browser-messaging-boundaries --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/cyberful/cyberful.git skills-src && mkdir -p .agents/skills && cp -r skills-src/cyberful/builtin/skills/test-browser-messaging-boundaries .agents/skills/test-browser-messaging-boundaries && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "test-browser-messaging-boundaries" agent skill from https://github.com/cyberful/cyberful/tree/main/cyberful/builtin/skills/test-browser-messaging-boundaries into .agents/skills/test-browser-messaging-boundaries/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "test-browser-messaging-boundaries", 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 cyberful/cyberful --skill test-browser-messaging-boundaries -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install cyberful/cyberful test-browser-messaging-boundaries --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/cyberful/cyberful.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/cyberful/builtin/skills/test-browser-messaging-boundaries .cursor/skills/test-browser-messaging-boundaries && 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 "test-browser-messaging-boundaries" agent skill from https://github.com/cyberful/cyberful/tree/main/cyberful/builtin/skills/test-browser-messaging-boundaries into .cursor/skills/test-browser-messaging-boundaries/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "test-browser-messaging-boundaries", 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/cyberful/cyberful.git --path cyberful/builtin/skills/test-browser-messaging-boundaries--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 cyberful/cyberful --skill test-browser-messaging-boundaries -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install cyberful/cyberful test-browser-messaging-boundaries --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/cyberful/cyberful.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/cyberful/builtin/skills/test-browser-messaging-boundaries .gemini/skills/test-browser-messaging-boundaries && 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 "test-browser-messaging-boundaries" agent skill from https://github.com/cyberful/cyberful/tree/main/cyberful/builtin/skills/test-browser-messaging-boundaries into .gemini/skills/test-browser-messaging-boundaries/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "test-browser-messaging-boundaries", 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 cyberful/cyberful test-browser-messaging-boundariesInstalls 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 cyberful/cyberful --skill test-browser-messaging-boundaries -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/cyberful/cyberful.git skills-src && mkdir -p .github/skills && cp -r skills-src/cyberful/builtin/skills/test-browser-messaging-boundaries .github/skills/test-browser-messaging-boundaries && 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 "test-browser-messaging-boundaries" agent skill from https://github.com/cyberful/cyberful/tree/main/cyberful/builtin/skills/test-browser-messaging-boundaries into .github/skills/test-browser-messaging-boundaries/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "test-browser-messaging-boundaries", 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 cyberful/cyberful --skill test-browser-messaging-boundaries -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install cyberful/cyberful test-browser-messaging-boundaries --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/cyberful/cyberful.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/cyberful/builtin/skills/test-browser-messaging-boundaries .opencode/skills/test-browser-messaging-boundaries && 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 "test-browser-messaging-boundaries" agent skill from https://github.com/cyberful/cyberful/tree/main/cyberful/builtin/skills/test-browser-messaging-boundaries into .opencode/skills/test-browser-messaging-boundaries/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "test-browser-messaging-boundaries", 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
test-browser-messaging-boundaries- GitHub stars
- 135
- Token cost
- ~583 tokens
- SKILL.md length
- 162 words
- Files
- 5 (incl. references, assets)
- Skills in repo
- 85
- Repo updated
- First seen
- Licence
- AGPL-3.0
At a glance
Test browser capability transfer across postMessage, opener, frame, portal, worker, service-worker, BroadcastChannel, MessagePort, and extension messaging boundaries.
- Origin-validation
- SKILL.md covers Map channels and capabilities, Test minimally and Confirmation standard
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
- Navigation-race
What it does
Test Browser Messaging Boundaries is an agent skill from cyberful/cyberful. Test browser capability transfer across postMessage, opener, frame, portal, worker, service-worker, BroadcastChannel, MessagePort, and extension messaging boundaries. Use for origin-validation, source-binding, navigation-race, confused-deputy, channel-isolation, structured-clone, or privileged-message review.
Its SKILL.md is about 580 tokens, which your agent loads only when the skill is triggered. The skill folder holds 7 other files, including reference files and assets (for example `agents/openai.yaml`, `assets/browser-message-matrix.example.json` and `assets/browser-message-matrix.schema.json`).
It sits in Security. The repository describes itself as: Cyberful is an open-source AI Red Team for discovering, exploiting, verifying, and remediating vulnerabilities. The licence is AGPL-3.0.
When your agent uses it
- Origin-validation
- Navigation-race
- Confused-deputy
- Channel-isolation
Example prompts
- “/test-browser-messaging-boundaries”
What it can do on your machine
Read from SKILL.md and the folder at commit ec598a6. 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
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
Test Browser Messaging Boundaries loads about 583 tokens when it runs, and up to ~798 if it reads all its reference files. Until then it costs about 86 tokens; SKILL.md has 162 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 cyberful/cyberful at commit ec598a6, republished under its AGPL-3.0 licence (© cyberful). 162 words, ~583 tokens.
Download SKILL.mdSave it as
.claude/skills/test-browser-messaging-boundaries/SKILL.md (or your agent's skills folder). This skill also uses 4 other files; get the full folder from GitHub.- name
- test-browser-messaging-boundaries
- description
- Test browser capability transfer across postMessage, opener, frame, portal, worker, service-worker, BroadcastChannel, MessagePort, and extension messaging boundaries. Use for origin-validation, source-binding, navigation-race, confused-deputy, channel-isolation, structured-clone, or privileged-message review.
- metadata.domain
- application-security
- metadata.subdomain
- browser-messaging
- metadata.triggers
- postMessage security, cross frame messaging, opener trust boundary, worker message authorization, browser extension messaging, BroadcastChannel isolation
- metadata.tags
- browser, postMessage, iframe, worker, extension, origin-policy
Test Browser Messaging Boundaries
Treat every message as a capability-bearing request. Validate sender origin, sender object, destination, message schema, freshness, and operation-level authority at the receiving boundary.
Map channels and capabilities
Start from assets/browser-message-matrix.example.json and preserve assets/browser-message-matrix.schema.json. Include windows, frames, popups, portals, dedicated and shared workers, service workers, BroadcastChannel, MessagePort transfers, content scripts, extension pages, and native bridges.
Read references/message-capability-model.md for sender and receiver invariants. Record navigation and lifecycle transitions because a previously trusted window reference can later host an untrusted origin.
Test minimally
Use controlled origins and principals. Vary origin, source, channel, type, schema, target origin, ordering, replay, navigation timing, and transferred objects one dimension at a time. Observe the privileged operation or state transition, not just listener acceptance.
Confirmation standard
Report sender and receiver contexts, exact message, validation order, transferred capability, navigation or lifecycle prerequisite, matched control, current authorization, security effect, and browser constraints. A wildcard target origin or missing check is a weakness until reachability and effect are proven.
© cyberful, AGPL-3.0. 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 4 other files (references, assets) in cyberful/builtin/skills/test-browser-messaging-boundaries of cyberful/cyberful.
- SKILL.md
- agents/openai.yaml
- assets/browser-message-matrix.example.json
- assets/browser-message-matrix.schema.json
- references/message-capability-model.md
Open the folder on GitHubat commit ec598a6
Compare with similar skills
Test Browser Messaging Boundaries 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 |
|---|---|---|---|---|---|---|
| Test Browser Messaging Boundaries this skillcyberful/cyberful | 135 | — | ~583 | Automated safety check: Pass | AGPL-3.0 | |
| Fla Ascend Performancefla-org/flash-linear-attention | 5.8k | — | ~6.3k | Automated safety check: Pass | MIT | |
| Deepsec Documentation Guidevercel-labs/deepsec | 8.1k | — | ~956 | Automated safety check: Pass | Apache-2.0 | |
| Skill Scannergetsentry/skills | 1k | 4 repos | ~2.5k | Automated safety check: Warn | Apache-2.0 | |
| Serenity Aleabitoreddityan-labs/serenity-aleabitoreddit | 481 | 1 repos | ~3.3k | Automated safety check: Pass | None | |
| Security Alert Triageelastic/agent-skills | 592 | 1 repos | ~3.5k | Automated safety check: Notes | Apache-2.0 |
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Categories
Questions about Test Browser Messaging Boundaries
What does Test Browser Messaging Boundaries do?
Test browser capability transfer across postMessage, opener, frame, portal, worker, service-worker, BroadcastChannel, MessagePort, and extension messaging boundaries. Test Browser Messaging Boundaries is an agent skill from cyberful/cyberful. Test browser capability transfer across postMessage, opener, frame, portal, worker, service-worker, BroadcastChannel, MessagePort, and extension messaging boundaries.
When should I use Test Browser Messaging Boundaries?
Test Browser Messaging Boundaries fits situations like: origin-validation; navigation-race; confused-deputy; channel-isolation.
How do I install Test Browser Messaging Boundaries in Claude Code?
Run `npx skills add cyberful/cyberful --skill test-browser-messaging-boundaries -a claude-code`. Or copy the skill folder (cyberful/builtin/skills/test-browser-messaging-boundaries in cyberful/cyberful) into .claude/skills/test-browser-messaging-boundaries in your project. Claude Code loads it when a task matches its description.
How do I install Test Browser Messaging Boundaries in Codex?
Run `npx skills add cyberful/cyberful --skill test-browser-messaging-boundaries -a codex`. Or copy the skill folder (cyberful/builtin/skills/test-browser-messaging-boundaries in cyberful/cyberful) into .agents/skills/test-browser-messaging-boundaries in your project. Codex loads it when a task matches its description.
Can I use Test Browser Messaging Boundaries 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 cyberful/cyberful --skill test-browser-messaging-boundaries -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/test-browser-messaging-boundaries, .gemini/skills/test-browser-messaging-boundaries, .github/skills/test-browser-messaging-boundaries and .opencode/skills/test-browser-messaging-boundaries in your project.
What does Test Browser Messaging Boundaries need to run?
SKILL.md names no scripts, command-line tools or credentials: Test Browser Messaging Boundaries is instructions for the agent only.
Does Test Browser Messaging Boundaries 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 Test Browser Messaging Boundaries 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 Test Browser Messaging Boundaries use?
Test Browser Messaging Boundaries is published under the AGPL-3.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.
How many tokens does Test Browser Messaging Boundaries use?
About 583 tokens (SKILL.md is roughly 2.3k 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 215 tokens, read only when the agent opens those files.
What are the alternatives to Test Browser Messaging Boundaries?
Skills that share tags, products or a category with Test Browser Messaging Boundaries: Fla Ascend Performance (fla-org/flash-linear-attention, 5.8k stars), Deepsec Documentation Guide (vercel-labs/deepsec, 8.1k stars), Skill Scanner (getsentry/skills, 1k stars) and Serenity Aleabitoreddit (yan-labs/serenity-aleabitoreddit, 481 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Test Browser Messaging Boundaries?
cyberful (a GitHub organization) maintains it in cyberful/cyberful, which has 135 GitHub stars. The repository holds 85 skills in this directory. The repository was last updated on August 24, 2026.
Source: cyberful/cyberful on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.