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.
npx agentmods add skills/xenitv1/claude-code-maestro/browser-extensionnpx skills add xenitV1/claude-code-maestro --skill browser-extensiongit clone --depth 1 https://github.com/xenitV1/claude-code-maestroWrote 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.
[](https://agentmods.dev/skills/xenitv1/claude-code-maestro/browser-extension)<a href="https://agentmods.dev/skills/xenitv1/claude-code-maestro/browser-extension"><img src="https://agentmods.dev/badge/skills/xenitv1/claude-code-maestro/browser-extension.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00046 | $0.01149 |
| Opus 5 | $0.00023 | $0.00575 |
| Sonnet 5 | $0.00009 | $0.00230 |
| Haiku 4.5 | $0.00005 | $0.00115 |
Grade A, and why
browser-extension 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 6d 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.
How it starts
The opening of the file, as written. The whole thing — 72 lines — stays where its author put it; the contents beside it link to each section on GitHub.
<domain_overview>
🌐 BROWSER EXTENSION: THE 2026 MASTERCLASS
Philosophy: Extensions are ephemeral, restricted, yet powerful. Persistence is an Art. Security is a Mandate. Design Constraint: For UI/UX, Aesthetics, and Layout, YOU MUST REFER TO THE
frontend-designSKILL. PERSISTENCE PARADOX GUARD (CRITICAL): Never rely on global variables or in-memory state in background scripts. AI-generated code frequently fails by assuming Manifest V3 service workers are persistent. They are NOT; they terminate after 30 seconds of inactivity. You MUST backup every piece of state tochrome.storageorIndexedDBimmediately upon change. This skill aims to eliminate "volatile-state" bugs typical of generic AI implementations. If data is not in durable storage, it does not exist. </domain_overview> <manifest_architecture>
🏗️ PROTOCOL 1: THE MANIFEST V3 CONSTITUTION
All extensions must be built on Manifest v3. No exceptions.
- Manifest Blueprint:
- Service Workers: No persistent background pages. Use
"background": { "service_worker": "background.js" }. - No Remote Code: All scripts must be local.
unsafe-evalis forbidden. - Permissions: Principle of Least Privilege. Use
optional_permissionswhere possible. - Action UI: Prefer
actionoverbrowser_actionorpage_action.
- Service Workers: No persistent background pages. Use
- Side Panel Supremacy:
- Requirement: Use
chrome.sidePanelfor persistent, non-intrusive experiences. - API:
chrome.sidePanel.setOptions({ path: 'sidepanel.html', enabled: true }). </manifest_architecture> <persistence_engine>
- Requirement: Use
⚡ PROTOCOL 2: THE PERSISTENCE ENGINE (ANTI-TERMINATION)
Service Workers sleep. You must keep the logic alive.
- The Alarm Pulse:
- Use
chrome.alarmsto wake up the Service Worker every 1-5 minutes for background sync.
- Use
- The Offscreen Document (When needed):
- Use the
offscreenAPI for tasks like DOM parsing, heavy calculations, or keeping the SW alive via periodic messaging.
- Use the
- State Management Protocol:
- NEVER rely on global variables.
- Mandatory: Use
chrome.storage.sessionfor transient session-only secrets. - Mandatory: Use
IndexedDBorchrome.storage.localfor large datasets and persistent user data. </persistence_engine> <security_fortress>
What ships with it
3 files 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.
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.
- 6d ago First seen · 72 lines · 46 tokens per session scan A 9be2b8b2a5a5
browser-extension is a skill published in the GitHub repository xenitV1/claude-code-maestro (230 stars, last pushed 7mo ago), licensed MIT. It adds 46 tokens to every session and 1,149 once invoked, about $0.0002 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.
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